Controversies in Knee Surgery V Programme

The Knee 9 Ž2002. 77᎐97

Abstracts Controversies in Knee Surgery V Programme June 7᎐8 2001

Articular cartilage degradation following anterior cruciate ligament rupture Derek Bickerstaff Sheffield, UK Aim To determine if degradation of cartilage matrix in primary osteoarthritis ŽOA. or in OA secondary to rupture of the anterior cruciate ligament is a gradual response to excessive loading or an early, initiating event in the disease process.

recurrent instability causing medial lesions, postero-medial ligament to capsular lesions. These primary and secondary anatomical lesions that induce an imbalance in the transmission of forces are those likely to lead to OA. This imbalance does exist in both frontal and sagittal planes. Characteristic features of OA after anterior chronic laxity are: 䢇

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Methods Cartilage biopsies were removed from the low weight-bearing articular cartilage of the inter-condylar notch of patients undergoing knee arthroscopy ŽACL injury., arthroplasty Žlate-stage primary OA. or from controls. In some cases, biopsies were also removed from the high weight-bearing area cartilage of the femoral condyles. Biopsies were extracted and assayed for total and denatured type II collagen by inhibition ELISA and for proteoglycan using a colorimetric method. All patients were assessed for cartilage erosion by X-ray score. In addition, the cartilage of patients with ACL injury was assessed at arthroscopy and the knee function of primary OA patients was assessed using the WOMAC index. Results Increasing type II collagen degradation in late-stage OA was detected in the low as well as the high weight-bearing cartilage and there was a positive correlation between the percentage denatured collagen and the WOMAC index. Most of the patients with ACL injury had no clinical signs of OA or the macroscopic cartilage erosion. However, the low weight-bearing articular cartilage from these patients showed a significant increase in type II collagen degradation, similar to that observed in late-stage OA. The proteoglycan content of articular cartilage did not change significantly in OA or ACL injury compared to controls. Conclusion Type II collagen degradation is an early event following ACL injury and is unlikely to be a direct result of mechanical loading, since it was observed in cartilage taken from a low weight-bearing site. The onset of OA secondary to ACL rupture might be delayed or prevented by early treatment with inhibitors of collagenases and this possibility should now be investigated. Does ACL reconstruction influence the progression of OA? P. Neyret Lyon, France

This is an example 15 years after ACL rupture. This patient had had an ACL rupture 43 years ago. Few studies allow us to know the incidence of OA after ACL rupture and they are retrospective andror based on short-term follow-up. Very often a meniscectomy has been performed. McDaniel and Cameron found a space joint narrowing or a frank osteoarthritis in only 27% of cases, 10 years after ACL rupture. Their radiological findings correspond favourably with those in the series of Johnson who described 99 knees following meniscectomies and had a 39% incidence of pre- or frank osteoarthritis. We know the functional and radiological outcome of medial meniscectomy in which the meniscal lesion is a complication of an ACL rupture. We reported with Simon Donell the rate of OA in 91 meniscectomized ACL deficient knee at minimum follow-up of 20 years. We also reported the radiological outcome of medial meniscectomy in ACL deficient knee at 27 years follow-up. The question of how a meniscus injury or meniscectomy may influence this course has not been well investigated. However, it seems that the progress of radiological feature is governed not only by the ligamentous lesion, but also by the meniscal lesion. Radiological analysis helps the physician to follow the progress of radiolocal features and to identify the factors influencing the development of OA. Mechanical factors: ACL rupture; meniscal tears; peripheral lesions; osseous deformities like tibial varus; or tibial slope are potential factors. Age, level of activity, and overweight are not well documented. Clinical or genetic factors will be better understood in the future. In parallel with this, other published works have shown that rupture of the ACL that has been repaired or reconstructed also leads to OA. We have now identified several iatrogenic gestures: 䢇 䢇

Following ACL rupture, secondary lesions occur as a result of

Disappearance of the clear posterior triangle of the posterior horn of the meniscus Anterior tibial translation Postero medial cupula

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Isolated extra articular reconstruction Synthetic ligament Manipulation under anaesthesia

0968-0160r02r$ - see front matter 䊚 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 6 8 - 0 1 6 0 Ž 0 1 . 0 0 1 4 9 - 1

Abstracts

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One disadvantage of ACL graft is that it is also liable to speed the development of OA. We reported with H. Dejour in 1988 that four non-independent factors can whip out osteoarthritis after ACL reconstruction. We found several factors liable to influence the onset of osteoarthritis: 䢇 䢇 䢇 䢇

previous medial meniscectomy; delay injury-operation; age at time of surgery; and preoperative radiological changes.

Three very similar retrospective Lyonnais series of ACL reconstruction Žusing the free third of patellar tendon. combined to extra-articular tenodesis were reported by Aıt ¨ Si Selmi, Selva and Chotel at more than 10 years follow-up. What are the radiological results reported by T. Aıt ¨ Si Selmi? In 1995, T. Aıt ¨ Si Selmi reported the outcome of 148 ACL free grafts associated with an extra-articular tenodesis ŽDejour’s operation. at 11.5 years mean follow-up. At 11 years follow-up, the rate of pre-OA and OA in these three series, ranged from 15 to 30%. This osteoarthritis was relatively well tolerated and less than 5% of patients had required a high tibial osteotomy due to OA. T. Aıt ¨ Si Selmi highlighted two factors that can lead to degenerative changes: medial meniscectomy and residual tibial translation. What are now the radiological results reported by Chotel and Selva after ACL reconstruction, combined to an extra-articular tenodesis at 10 years follow-up. Chotel and Selva also found a relationship between the medial meniscal status and radiological outcome. They also observed 91% normal or nearly normal X-rays at 11-years follow-up in the case of preserved medial meniscus. Nearly normal was defined by a very limited flattening of medial condyle Žmodelling. without narrowing of joint line. If the medial meniscus was preserved it means normal of sutured at time of ACL reconstruction, the rate of pre-OA or OA was 10% at 11.5-years mean follow-up. But if the medial meniscus was partially removed at the time of ACL reconstruction the rate of pre-OA or OA increased to 20 and 30%. In the case of total meniscectomy Žbefore the ACL reconstruction . was the worst eventuality; the risk of pre-OA or OA reached to 60%. The influence of post-operative medial meniscectomy after ACL reconstruction in the onset of OA is still unknown because its frequency was very low. From the series of 148 patients reported by T. Aıt ¨ Si Selmi, reviewed in 1992, we followed 110 patients at 17 years after ACL reconstruction. Overall, 59 patients had undergone partial or compete medial meniscectomy either before or at reconstruction. The other 44 patients had a medial meniscus that was healthy or had been sutured. Twelve meniscus sutures had been performed, between 1981 and 1983, through an arthrotomy posterior to the collateral ligament, using vertical absorbable sutures. Since the Dejour reconstruction, nine medial meniscectomies had been performed. In four cases, a ‘healthy meniscus’ had been removed; the remaining five were in the group of 12 patients who had had meniscal suturing. At follow-up, radiography showed 38% of the knee to be normal, 23% to have remodelling, 20% pre-OA and 19% established OA. Patients with normal X-rays in 1992 still have normal X-rays in 1999. This is an example of normal X-ray at 18-years follow-up. In the other example, this is a grade D with narrowing of the medial T.F. compartment. Of the patients who had undergone medial meniscectomy, 47% had pre-osteoarthritis or established OA. OA were seen to affect the medial T.F. compartment in 66% of cases. Of the patients with healthy or sutured meniscus, 25% had pre-OA or OA. In the absence of ACL reconstruction, osteoarthritis is regularly

observed, between 20 and 40 years after the injury, but there is no true prospective study with 20-years follow-up. Results of ACL reconstruction are, from now, known at 10᎐20years follow-up. When the medial meniscus is preserved we report 22 of pre-OA and 3% OA at 17-years follow-up. The take home message of this talk is: One must take into account not only the instability in his decision, but also long-term effects and particularly degenerative changes that appear to be a key feature of the indication in these young patients. Tibial tunnel widening after ACL reconstruction: a 2- and 5-year comparison of patellar tendon autograft and 4-strand hamstring tendon autograft LA Pinczewski Sydney, Australia Objecti¨ e To confirm previous studies and reports of tunnel widening following ACL reconstruction. To report the medium-term behaviour and the effect of tunnel widening on clinical results. Methods A retrospective analysis of ACL database comparing BPTB autograft vs. HT autograft and interference screw fixation was carried out. All procedures were performed by the same surgeon using an identical endoscopic single incision surgical technique and a single method of fixation Ž7 = 25-mm titanium RCI screw.. Patients who had radiographic series at 2 and 5 years were included in the study. All patients had an isolated ACL injury. Patients underwent a continuous follow-up evaluation including clinical examination IKDC, Lysholm knee score and KT-1000 man max testing. Tibial tunnel widening was calculated from lateral radiographs digitalised and corrected for magnification. Tunnel shape was classified according to Peyrache. Results Median HT tunnel area increased significantly from 0 to 2 years Ž P s 0.00. and was unchanged from 2 to 5 years. Median PT tunnel area decreased significantly from 0 to 2 years Ž Ps 0.03., and decreased again from 2 to 5 years Ž Ps 0.02.. A significant difference in tunnel shape exists between HT and PT groups Ž Ps 0.00.. Conclusion Tibial tunnel widening is confirmed after ACL reconstruction in 79% of HT and 24% of PT surgeries utilising a single titanium RCI screw fixation. Graft choice is shown to influence tibial tunnel shape, 21% of HT developed a cavity shape, and 29% of PT exhibit tunnel disappearance. All patients with a decrease in tunnel area had a negative pivot shift. This was significantly different from the tunnel-widening group. The graft selection debate J Bartlett Melbourne, Australia Recent years have seen consensus with regard to intra-articular anatomic reconstruction of the anterior cruciate ligament. Graft selection has been controversial employing autografts, allografts xenografts and prosthetics. Despite some continued use of alternatives, 98% of anterior cruciate ligament grafts employ autografts with approximately 70% being one third patellar tendon and 25% being hamstring grafts. This presentation explores research work into the relative merits of these graft materials. Conclusions based on our experience are: the absence of pain correlates best with

Abstracts patient satisfaction. Eighteen percent of semitendinosus gracilis grafts will have some hamstring symptoms. Fifteen percent of semitendinosus gracilis grafts will have some anterior knee symptoms. Sixty-five percent, if patellar tendon grafts, will have some anterior knee symptoms. Both patellar tendon and hamstring grafts will have 10% of quadriceps weakness. Semitendinosus gracilis will have 10 permit hamstring weakness. Accelerated rehabilitation with hamstring grafts can lead to tunnel widening. A comparison of patellar tendon and 4-strand hamstring tendon graft for ACL reconstruction: results of a prospective study at 5 years LA Pinczewski Sydney, Australia

initial injury will return to full sport with ) 90% predictability. Return to full sport can now be achieved by 5᎐8 months following surgery. Recreational athletes with chronic ACL instability are less likely to return to full sport Ž80%. and take longer Ž6᎐12 months. to reach this goal. A successful outcome requires a high strength graft with stable fixation. Immediate full weight bearing and restoration of a pain free full range of motion as soon as possible after surgery will minimise muscle atrophy. Well-motivated patients can return to full training and recreational sport by 3 months. For return to full competitive rugby following ACL reconstruction, I recommend the following criteria should be met: 䢇 䢇 䢇

Objecti¨ e The aim of this longitudinal study is to compare the clinical outcomes of endoscopic ACL reconstruction with either a 4-strand HT or PT autograft over a 5-year period, when a similar operative procedure is followed for both groups. Method Ninety patients with isolated ACL rupture received PT autograft and 90 received HT autograft were studied annually for 5 years, 50 patients were randomised as a subgroup. Assessment included the IKDC Knee Ligament Evaluation, KT1000, Lysholm Knee Score, thigh atrophy, kneeling pain, hamstring pain and radiographs. Results The median Lysholm Knee Score was 96 for the PT group and 95 for the HT group. No significant difference was found for subjective knee function, overall IKDC assessment, X-ray findings, manual ligament KT1000 instrumented testing, graft rupture or contralateral ACL rupture. There was an increasing incidence of fixed flexion deformity seen in the PT group. There was no difference in the requirement for subsequent surgery. The incidence of kneeling pain at 5 years was significantly higher in the PT group. The results of the randomised patients were identical to the sequential patients. Conclusion Endoscopic reconstruction of the ACL utilising either autograft can restore knee stability and is menisco protective despite a high level of sporting activity. We did find a worrying trend towards an increasing incidence of fixed flexion deformity with time in the PT group. Kneeling pain also remains a persistent problem in this subgroup. PT grafts appear tighter clinically and with KT 1000 up to 3 years post-operative, compared to HT grafts, but thereafter the results are similar. ACL reconstruction: rehabilitation overview B Tietjens Auckland, New Zealand In humans the clinical limitations of ACL reconstruction have yet to be defined. Prior to 1990, rehabilitation protocols based on animal studies emphasised protected joint loading and limited joint motion. Athletes seldom returned to full competitive sport less than 12 months following surgery. Shelbourne introduced the concept of accelerated rehabilitation based on observation of non-compliant patients. He has reported return to full sport 6.2" 2.3 months following surgery. Current rehabilitation protocols are based largely on clinical experience rather than experimental science. Competitive athletes undergoing ACL reconstruction following

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Minimum 5 months following surgery A stable knee on clinical or instrumented testing ) 90% quadriceps strength compared to the contralateral knee Confidence with functional agility tests Žhopping, side-stepping, shuttle runs.

When can I drive? J Bartlett Melbourne, Australia Driving is an important part of a modern lifestyle. ACL injury is the most common ligamentous injury of the knee. However, there is a paucity of information about the pre- and post-operative ability of an ACL injured knee to respond to stimuli for specific situation such as braking reaction in an emergency. Does an ACL unstable knee affect braking reaction time? If it does, is there a difference between left and right injured knee? When is it safe to resume driving after an ACL reconstructive surgery? Is there any simple clinical test to assess patient’s recovery after surgery? Braking reaction time of 73 patients whom underwent arthroscopic ACL reconstruction and 25 normal controls was prospectively studied using a computer-link automobile simulator. Majority of these patients had autologous hamstring tendon graft. Every patients and controls were tested pre-operatively and every 2 weeks after surgery up to 8 weeks. At each time point, two clinical tests namely stepping and standing test were also performed. The pre-operative results did not differ significantly between controls, left ACL group and right ACL group for the braking reaction time and the two clinical tests. Post-operatively, it took 6 weeks for braking reaction time of the right ACL group to be equivalent to that of the controls, compared to 2 weeks for the left ACL group. There were a strong correlation between the stepping and standing test and the braking reaction time at each time point. Conclusion An ACL unstable knee does not affect patient’s braking reaction time. After a right ACL reconstruction, patient should delay at least 6 weeks before resuming driving. However, patient may resume driving as early as 2 weeks after a left ACL reconstruction. The stepping and standing test can be used at follow-up to assess patient’s recovery after surgery and to suggest appropriate time to resume driving. Osteotomy in the unstable knee J Bartlett Melbourne, Australia Introduction In an increasingly higher number of patients anterior knee instability is combined with varus malalignment of the knee with medial compartment degenerative changes. In this group of patients a

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combined procedure for correction of both pathologies may be indicated. Material and methods Between 1993 and 1998 a total number of 19 patients underwent combined ACL reconstruction and HTO. These are 2% of all ACL reconstructions done in the above-mentioned period. Fifteen Ž79%. patients were followed clinically and radiologically at a mean follow-up of 47 months Žrange, 8᎐76 months.. There were 14 male and one female patients at a mean age of 43.6 years Žrange, 18᎐61 years. at follow-up. The predominating cause of injury was a non-contact trauma sustained at Australian rules football activities. All patients showed a positive Lachman and pivot shift test in the pre-operative examination under anaesthesia. All were chronically unstable with multiple instability episodes in the history. Medial compartment articular cartilage changes in the weightbearing area found at arthroscopy ranged from grade 2 to grade 4 ŽOuterbridge classification ., and all patients had a varus malalignment of 5⬚ or more. The procedure was started with a closed wedge osteotomy and was followed by an arthroscopically assisted ACL reconstruction with patellar tendon or quadruple hamstring grafts. The post-operative regimen comprised 6 weeks of partial weight-bearing in a long leg protective splint with intermittent range of motion exercises. We calculated the Lysholm score, determined the Tegner activity level and filled the IKDC knee ligament standard evaluation form. An instrumented laxity testing was performed with the KT 1000. Results Patients reached an average of 80.3 points in the Lysholm score. Most patients returned to recreational sports, which gave a result of 4.06 on the Tegner scale. The IKDC results were as follows: one Ž6.6%. normal; eight Ž53.3%. nearly normal; five Ž33.3%. abnormal; and one Ž6.6%. severely abnormal. The post-operative alignment was 8⬚ Žrange, 3᎐12 degrees. in the femoral tibial angle. Conclusion In patients with the above-mentioned combined pathology combined surgical correction can improve overall knee performance. Place of osteotomy in an osteoarthritic knee G. Puddu Rome, Italy Varus and valgus painful knee is a disabling condition especially in the young and middle age people. To correct this kind of deformity, tibial and femoral osteotomies are the most popular surgical procedure among the techniques described in the literature. The authors herein propose a technique of medial tibial opening wedge and lateral femoral opening wedge osteotomies based on a new system of plates fixation. Furthermore, some special dedicated instruments have been developed that greatly facilitate the performance of the operation. The indications and the limits of osteotomies are briefly considered before introducing the surgical techniques, which is described step-by-step and is well illustrated with many intra-operative pictures. Since 1993, the authors have designed and used in 30 patients with a varus knee, a special plate that has two holes for AO screws and a tooth on the middle. The height of the tooth is variable from 5 to 15 mm Ž5᎐7.5᎐10᎐12.5᎐15 mm., while the thickness is always 4 mm. In 14 cases a different plate with the same tooth, but with two

holes distally and four holes proximally was used for the femoral osteotomies in the valgus knee. The aim of those plates is to fix and to stabilise the opening wedge osteotomies. Once the tooth is introduced in the osteotomy, its height and thickness prevents a bone collapse and a loss of correction. Results On the follow up Ž4᎐1 years. the overall IKDC rating improved in 27 over 30 patients in the tibial osteotomy group. Pre-operatively all 30 patients scored for a abnormal or severely abnormal knee joint. Post-operatively all patients rated a nearly normal or abnormal knee with six patients having improved two categories. In the group of the femoral osteotomies all patients rated a nearly normal knee with four rated as abnormal. In the two groups all the osteotomies have completely healed between 2 and 3 months from surgery. Conclusions This technique of opening wedge osteotomies makes easier and simpler tibial and femoral osteotomies achieving the desired femoro-tibial alignment without any loss of correction. In particular in the tibial osteotomy it is not necessary to associate a fibular osteotomy or an excision or division of the fibular head. Alternative techniques for osteotomy in the unstable knee P. Neyret Lyon, France The natural history of the ACL rupture allows us to know different factors that influence the onset of OA as the Medial Meniscal status, amount of Anterior Tibial Translation or chondral lesions at injury. But ACL reconstruction can speed up the onset of OA, particularly if the time between injury and operation is more than 5 years, if there is a history of previous MM, or if degenerative changes are present on pre-operative X-rays. To detect these early radiological changes the check-up includes comparative monopodal stance AP and a lateral view Bipodal AP view at 45⬚ flexion Žschuss view., is very sensitive to detect slight posterior femoro᎐tibial narrowing. Comparative long leg films are used to measure the mechanical tibio᎐femoral axis. Physical examination Žalignment, thrust . and an X-ray check-up can detect an imbalance of forces across the knee. This imbalance can predominate in the frontal or sagittal plane. Our hypothesis was that any imbalance that appears on a monopodal stance cannot be compensated for by a simple ligamentous ACL graft. In the frontal plane, the contributing factors to imbalance are: 䢇 䢇

ACL rupture Medial meniscectomy.

A constitutional varus osseous deformity greater than 6⬚ is an another potential factor. Postero-lateral corner lesions is a separate entity. In the sagittal plane, the contributing factors to imbalance are: 䢇 䢇

ACL rupture Medial meniscectomy.

A constitutional posterior slope of the tibia greater than 13⬚ is an another potential factor. There is a direct relationship between the ATT and the tibial slope. To understand the indication of osteotomy in ACL insufficiency a classification is necessary. In the case of isolated or evolved anterior chronic laxity, there is

Abstracts no indication to combine an osteotomy to ACL reconstruction. Evolved means that secondary postero-medial lesions had occurred such as meniscal tear or stretching of the postero-medial capsule. At this stage if an ACL reconstruction is considered we must discuss others gestures as: 䢇 䢇 䢇

medial meniscus suture; extra-articular tenodesis; or or reefing of the postero-medial capsule.

There is no place for a HTO. In the case of postero-lateral ACL insufficiency, postero-lateral lesions occur during the injury. Clinical examination, particularly the recurvatum test described by Hughston, the asymmetrical joint opening and palpation of the lateral collateral ligament used by H. Dejour permit to test the different postero-lateral structures. An asymmetrical joint opening is searched on the comparative AP view. To reconstruct the ACL is not enough. We must also consider postero-lateral reconstruction and depending on the alignment an osteotomy. We recommend a one staged surgery. On this post-operative X-ray, we performed an ACL reconstruction combined with a lateral collateral reconstruction using a 6 mm wide contralateral bone᎐patellar tendon bone graft and an opening wedge HTO. When an asymmetrical lateral opening is present on monopodal stance, the LCL graft permits to avoid to overcorrect the tibia and to perform a slight hypercorrection in valgus. In this very special case of postero-lateral ACL insufficiency there is no lateral opening on monopodal stance, but the stress X-ray in varus demonstrates the LCL insufficiency. The alignment of the lower limb was in valgus. We reconstructed the ACL and the LCL. We did not perform any osteotomy. Ligament evaluation and functional result are still perfect at 4-years follow-up. In the absence of surgical treatment, over time degenerative changes are observed with kissing chondral damages. This stage is called ACL insufficiency with pre-OA. In ACL insufficiency with pre-OA patients complains mainly of instability. Pain or effusion are not constant. X-Rays permit to make the diagnosis. My recommendation is to always obtain X-rays when the time between injury and operation is more than 5 years, or in the case of a meniscectomized knee. Remember we must detect a frontal or sagittal imbalance because a simple ACL graft can lead quickly to severe OA. We must take into account this imbalance if we decide to perform an ACL reconstruction. In the case of frontal imbalance we combined a valgus HTO and an ACL reconstruction. Beware not to increase the tibial slope when performing an opening wedge osteotomy. Control of the residual ATT is highly correlated to the decreasing of the tibial slope. In the case of sagittal imbalance we combined an anti-recurvatum or deflexion osteotomy to the ACL reconstruction. At the stage of OA due to ACL insufficiency, the main complaint is OA and not ACL insufficiency. When there are kissing chondral lesions with subchondral bone exposed or a cupula, there is no place for ACL reconstructions. Treatment is the treatment of gonarthrosis. I just want to underline one specific point. Take into account the slope and chose closing wedge osteotomy over the opening wedge. I would like to highlight several points about the technique we use, which was reported previously. When an opening wedge, high tibial osteotomy is combined with an ACL reconstruction we harvest the graft, we drill the femoral and tibial tunnels and then we osteotomize the tibia. The osteotomy is fixed with staples and we calibrate the tibial tunnel. To perform the osteotomy we elevate the pes anserinus, and we cut

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transversally the superficial layer of the MCL. We place two pins to guide the osteotomy, we control the position of the pins and later amount of the correction with scopy. We prefer to fix the osteotomy with two staples. Tibial bone block is secured with a wire on a post. When a deflexion osteotomy is combined to ACL reconstruction, the different steps are very similar. At the end of the procedure according to the clinical evaluation, we tighten the posterior capsule to control the recurvatum. The two pins go from the anterior part of the anterior tibial tuberosity to the lower PCL fibres. A scopic control is always carried out. Up to now we have operated 66 patients with ACL and HTO, and four patients with ACL and deflexion osteotomy. From 1983 to 1999, we treated 66 knees by this combined procedure. We only studied the 47 ACL deficient knees that presented abnormal radiological findings in the medial tibiofemoral joint wremodelling changes Žgrade B, 35%., pre-arthritic changes Žgrade C, 65%.x. We excluded three knees with evolved osteoarthritis Žgrade D., 11 knees with asymmetrical opening of the lateral compartment and five knees with excessive constitutional genu varum without medial radiological compartmental changes. Thirtyfive Ž74.5%. of the 47 knees were retrospectively reviewed at 11 years mean follow-up Žrange, 1᎐16 years.. At review, 93% of the patients were very satisfied or satisfied with their operated knee. Subjective score including knee function, symptoms and activity level average 78r100 Žrange, 46᎐96.. Forty-eight percent of the patients could regularly practice leisure sports like tennis or skiing. The overall IKDC objective score was normal ŽA. in five knees Ž14%. and nearly normal ŽB. in 16 knees Ž46%.. It was abnormal ŽC. in 12 knees Ž34%. and severely abnormal ŽD. in two knees Ž6%.. The IKDC score was correlated with monopodal weight bearing translation pre- and post-operatively. In medial compartment, radiological progression of osteoarthrosis was seen in five knees Ž15%.; three of the 14 knees have evolved from grade B to C, and two of the 20 knees from grade C to D. Axial femoro-tibial correction was 6.8⬚ at follow-up in group B and 4.7⬚ in group C. In lateral compartment, remodelling changes occurred in 18 knees Ž53%. and pre osteoarthritic changes in two knees Ž6%. without correlation with axial correction. Patello-femoral osteoarthritis — an overview M Glasgow FRCS Norwich, UK Complications relating to the patello-femoral joint represented the largest single cause of problems in the early reports of results following total knee replacement. However, isolated patello-femeral disease has not really been considered a significant entity, and a recent postal survey of Orthopaedic Surgeons in the UK, which indicated that less than one third of Surgeons would routinely request a skyline X-ray as part of the investigation of patients with knee symptoms over the age of 40, would lend weight to the suggestions that this diagnosis is frequently missed. Previous X-ray studies, some of which were based purely on lateral and AP X-rays, have already suggested that up to 8% of patients with osteoarthritic changes in the knee have diseases isolated to the patello-femoral joint. A prospective study of 206 patients over the age of 40 presenting to the Knee Clinic for the first time with a variety of knee complaints is presented. All patients were investigated by means of routine AP, lateral and 25⬚ skyline X-rays. The results indicate that overall, the incidence of osteoarthritic changes in the knee was 63.6%, of which 9.2% represented isolated patello-femoral disease. This problem is not confined to females, and although the incidence was very low in

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males in the 40᎐60 age group, a surprising 1.4% out of a total of 82.7 with osteoarthritis in the knee had disease confined to the patello-femoral joint, and in females over the age of 60 the incidence was 13.6%. There are now nine commercially available patello-femoral implants available. They are all small volume and studies to date have been compromised by relatively short follow-up, diverse methods of assessment and the combination of uni-compartmental tibio-femeral replacement in some series. The results have not, so far, matched those of current total knee replacements. The two principal problems to date have been persistent patella instability noted in up to 40% of patients in one series. This problem has been largely addressed by: 1. improved implant design 2. an appreciation of the fact that many patients with isolated patello-femoral osteoarthritis are in effect, end stage patellofemoral instability. Careful attention to patella tracking during surgery is essential. Persistent concerns have also been expressed about the potential for progression of medial compartment tibio-femoral disease, and there is now growing evidence of the relationships between medial facet patello-femoral osteoarthritis and medial tibio disease. The significant reduction in overall operative morbidity, the more rapid rehabilitation and the quality of result in satisfactory cases, should provide increasing incentive to continue to take a serious look at isolated patello-femoral replacement, and it is hoped that the implant manufacturers will make available increasing resources for development of further implants for use in the management of a condition that occurs much more frequently than has previously been recognised. Facetectomy S Donell Norwich, UK Patellofemoral arthritis may affect the whole patella, the medial facet, or the lateral facet. If the disease is isolated to the lateral patellofemoral joint, it is probable that it is the end-stage of extensor mechanism malalignment. This includes the spectrum of disorders from lateral hyperpressure syndrome to lateral patellar subluxation. In these circumstances there is logic in performing a lateral retinacular release. If, however, there are lateral marginal osteophytes, particularly of the ‘dripping candle wax’ type, then lateral release will fail as the patella will remained trapped over the lateral condylar ridge. In these circumstances removing the osteophytes and the lateral edge of the patella Žfacetectomy. can be beneficial. Open arthrotomy and excision is the standard method, and some have excised nearly the whole of the lateral facet. Martens and De Rycke Ž1990. have reported 90% good-to-moderate results at 2 years follow-up. However, Beltran Ž1987. showed 60% were painfree at 31 months. I prefer an arthroscopic approach removing the lateral osteophytes with a burr passed through the anterolateral portal followed by a lateral release using a Smillie knife, under direct vision. The operation is performed as a day case and benefits approximately 50% of patients. If it fails it does not preclude joint replacement, although in small patients it may be difficult to fit a small button. The results are unpredictable, although initially good. Weaver et al. reported that 70% of patients are unsatisfactory over a 3᎐12-year period. It is a useful operation to bind time. It is important that the patients have good quadriceps power pre-operatively, otherwise rehabilitation may be prolonged. Building up the quadriceps may abolish the symptoms of patellofemoral

arthritis thus avoiding an operation. Facetectomy does not treat hip arthritis. The technique of open wedge femoral osteotomies G Puddu Rome, Italy Open wedge femoral osteotomy Indications Congenital femoral valgus, early cartilage deterioration after a lateral meniscectomy, initial lateral femoral arthritis. To make the diagnosis the surgeon needs a standing radiography with the hip and ankles included and a Rosenberg view in A.P. at 40⬚ of knee flexion. In doubtful cases an MRI can help the decision showing the stress of the subchondral bone in the lateral compartment of the knee. We make an oblique incomplete osteotomy leaving an hinge of 5᎐10 mm on the medial side of the knee. The purpose of the osteotomy is to bring the mechanical axis at the centre of the knee. We should never make an ipercorrection changing a valgus knee in a varus knee. The femoral plates ŽPuddu plates made by Arthrex., specially designed for this osteotomy, are T-shaped with seven holes. Their peculiarity is a spacer, a ‘tooth’ as it were, available in six different sizes from 5 to 17.5 mm in thickness. The tooth enters into the osteotomy line, holding the correction chosen by the surgeon and preventing a later collapse of the bone with the recurrence of the deformity. The thickness of the chosen spacer must coincide with the desired angle of correction, calculated in advance in the preoperative planning. The three holes in the horizontal arm of the plate allow the introduction of two or three cancellous screws and the four holes in the vertical arm are cut for the cortical screws. The crucial point of the operation is the opening of the bone after the incomplete osteotomy at the desired angle of correction and holding the position to allow the introduction of the plate tooth. A very simple wedge opener greatly facilitates this step. It has two wedge-shaped branches, graduated to allow the opening at the correct rate, and a removable handle to allow the positioning of the plate. Surgical technique Lateral incision, drill a Steinmann pin under a fluoroscopic control, make the incomplete osteotomy initially with a saw and then with an osteotome Žsaw and osteotome have to be proximal to the osteotomy to protect the distal femur from a possible fracture ., opening the wedge, application of the plate, control of the alignment with a special road, plate fixation, bone grafting. Bone grafting can be made with autologous bone from the iliac crest or with a bone substitute. Post-operati¨ e Brace, CPM from the first day, partial weight-bearing at 45 days, full weight-bearing at 60 days. Tibial medial closing wedge osteotomy As opposed to a femoral opening wedge lateral osteotomy in special cases of a minor valgus knee the correction can be made with a medial tibial closing wedge osteotomy. But a varus tibial osteotomy can create an oblique joint line. This modification, however, is both efficient in extension and in flexion. Surgical technique The osteotomy site is localised with a Steinmann wire with the aids of fluoroscopy as with the femoral osteotomy. The most important

Abstracts area is the hinge at the lateral cortical epiphysis. This area must be localised at or above the tibio-fibular joint. A horizontal incision is made trough capsular and medial collateral ligament one cm above the pes anserinus. Resection must be minimal and can be performed progressively under fluoroscopic control or in accordance with preoperative calculations. Once the bone is taken out, the knee is forced in varus and the osteotomy fixation if performed with a special plate ŽArthrex. with two proximal and two distal holes that permits the introduction of two cancellous screws proximally and two cortical screws distally. Post-operati¨ e A brace, CPM, partial weight-bearing at 30 days and fully weightbearing between 30 and 45 days. Pre-operative and Intra-operative management of infection C Dodd Oxford, UK The diagnosis and management of the infected knee arthroplasty remains one of the most challenging aspects of knee surgery. Whilst the history can often give an index of suspicion and the clinical examination reveal an obvious case of infection, frequently the history and clinical course is less obvious and the pre-operative diagnosis far from certain. Serial screened X-rays remain the most reliable pre-operative indicator of infection. Progressive osteolysis beneath the tibial component is most characteristic. Isotope imagining studies particularly early on are often unhelpful, and there are two principal pre-operative diagnostic techniques. Pre-operative aspiration Žthe Sheffield technique . has proved a vital technique in dedicated centres with full back up. Alternatively intra-operative frozen section analysis ŽOxford technique . is gaining increasing acceptance as a very specific and sensitive method of pre-operative diagnosis. Early aggressive surgical management in the acutely infected knee replacement is gaining increasing acceptance. Arthroscopic lavage with 4᎐5 l of saline or open debridement if there is an area of wound breakdown, must be undertaken within 48 h to have a realistic chance of prosthetic salvage. It is essential to obtain metalwork cover for any hope of salvage and high doses of intravenous antibiotics are required. In the chronic case salvage management may be indicated in the old and infirm with poor soft tissues and loss of bone stock. Long-term suppressive therapy may be considered. On occasions it may be possible to achieve satisfactory function even with a discharging sinus. In the chronic infected case, an increasing consensus towards 2-stage revision is emerging. Intra-operative assessment with frozen section analysis is increasingly adopted and a 2-stage procedure is adopted if there is any likelihood of infection. The first stage centres around prosthetic removal with thorough debridement and insertion of an antibiotic impregnated cement spacer. A minimum of 6 weeks intravenous antibiotic therapy is then commenced and the second stage considered at the 2-month mark. With this regime there is a 90% q chance of irradicating the infection. The management of the infected knee replacement with an articulating spacer FS Haddad London, UK Infection continues to be one of the most challenging complications of knee replacement surgery. An increasing number of diagnostic and management modalities are available. These include antibiotic suppression, debridement with retention of the prosthesis, one

83

stage revision with antibiotic loaded cement, and two-stage revision. There are also the fallback options of excision arthroplasty, arthrodesis and in extreme circumstances, amputationrlimb ablation. The major drawback of two-stage exchange arthroplasty is that the interval period is often associated with limited mobility, limited stability, and with pain. The reimplantation procedure is often difficult because of scar formation within the knee. In order to help preserve limb length and minimise soft tissue contractures, several techniques have been described. These include the use of nonarticulating antibiotic-loaded cement spacers during the interval period. In addition to their ability to elute high levels of antibiotics, these spacers decrease the scarring within the joint space and facilitate reimplantation. The revision procedure is still difficult; however, and scarring is still substantial, particularly in the lateral and medial gutters and posteriorly. Moreover, these spacer blocks are often unstable and may lead to bone erosion. The Prosthesis of Antibiotic-Loaded Acrylic Cement ŽPROSTALAC. is an interim functional spacer that is manufactured primarily of antibiotic-loaded cement and that resembles a knee replacement. It is used between stages in two-stage exchange arthroplasty for the treatment of the infected total knee replacement. Forty-five consecutive patients who were treated over a 9-year period were reviewed. The average follow-up was 48 months Ž20᎐112 months., with a minimum follow-up of 2 years with the exception of two deceased patients. At final review, 41 out of 45 patients were free of infection Ž91%., but only one of 45 patients presented with a recurrent infection with the same organism. The range of motion was well maintained between stages. Complications were primarily related to the extensor mechanism and to knee stability between stages. To a large extent, both of these problems were improved with the refinement of the design of the implant. The PROSTALAC allows continuous rehabilitation between stages as it maintains good alignment and stability of the knee and a reasonable range of motion. It also helps to maintain soft tissue planes, which facilitates the second stage. The infection cure rate of 91% is similar to that reported using other methods and suggests that the movement allowed does not compromise the primary aims of the procedure. Patella instability — the Lyonnais view Ph Neyret Lyon, France In the study of patellofemoral pathology, the problem of terminology arises, in particular regarding the notion of instability. We need to know whether the patella can become dislocated or not. Subjective Patellar Instability ŽSPI. means ‘the feeling the patient has that the knee is not firm, that it will give way’. SPI may be a tendency to subluxation but may equally be something else; amyotrophy of the quadriceps, chondromalacia through direct blow, etc. If the patella is or has already been dislocated, we use the term ‘Objective Patellar Instability’ ŽOPI.. Potential patellar instability is when there are the anatomical features associated with patellar instability but no previous history of dislocation. As an aside, painful patellar syndrome is when a patient presents with clinical evidence of pain arising from around the patella, but no radiological evidence to suggest patellar instability. Richerand was the first to note an abnormality of the lateral femoral condyle in recurrent dislocations of the patella. Brattstrom defined intercondylar dysplasia as an exaggerated opening of the groove and a defect in the development of the margins of the groove. Maldague and Malghem in 1985 were the first to use the lateral view of the knee to detect inadequacies of the intercondylar

Abstracts

84

groove and lateral malpositions of the patella. Dejour and Walch defined actual criteria of trochlear dysplasia. The aim of the investigation of the ‘Lyonnais’ school was to make a qualitative and quantitative study of the intercondylar groove in lateral views of the knee in normal and pathological populations to define the precise place of this abnormality in patellar instability. One hundred and ten patients were included in this study. The mode of presentation of all of these patients was a true dislocation, either for the first time or a recurrent episode. These study radiographs were compared as well as radiographs of 190 control knees. There was one fundamental factor of patellar instability: trochlear dysplasia. Trochlear dysplasia was defined by reproducible features of the femoral trochlea: the crossing sign; and the trochlear bump. The crossing sign was a simple and characteristic image, a qualitative criterion of trochlear dysplasia. At a given point, the line of the trochlear floor crosses the anterior contour of the lateral femoral condyle and the trochlea is considered flat at this level. The crossing may have different appearances, which distinguished three types of trochlear dysplasia in our study population. We found the crossing sign present in 96% of cases, compared to its presence of only 3% in the control group. This sign is fundamental. The trochlear bump is a quantitative characteristic that is particularly significant in trochlear dysplasia. We measure the distance between anterior edge of the lateral condyle and the anterior cortex. We found a pathological threshold value which is 3 mm for the measurement of the trochlear bump. Sixty-six percent of knees with objective patellar instability had an anterior trochlear floor translation of 3.0 mm or more, as compared to only 6% of control knees. The more the trochlear bump, the more the dysplasia. More recently, David Dejour described a new classification using four grades based upon X-rays and CT-Scan analysis ŽGrade A, Grade B, Grade C and Grade D.. After trochlear dysplasia, the fundamental factor, there are three principles factors of patellar instability: 䢇 䢇 䢇

Patellar height TT᎐TG Quadriceps dysplasia.

The height of the patella is very difficult to measure, and the reliability of the measurement is still unsatisfactory. We used the index of Caton and Deschamps. This is the ratio between the distance of the lower edge of the patellar joint surface to the upper edge of the tibial plateau and the length of the patellar articular surface. The control subjects have a mean index of 0.95, whereas in the OPI group the mean is the 1.12. There is a significant difference between these two groups. If the index is superior to 1.2, the patella is high. In our experience, the patella alta is due to excessive length of the patellar tendon rather than proximal insertion onto the tibial tuberosity. We presented a study in Lyon during the IPSG in 98 to compare the length of patellar tendon measured with MRI and XR in a control group and an objective patellar instability group. We found longer patellar tendon in the OPI group than in the control group. We demonstrated that patella alta is due to a too long patellar tendon and not due to a too high insertion of this tendon on the tibia. Goutallier and Bernageau have refined the concept of excessive TT-TG and made it radiologically measurable. The TT-TG, measured by a CT-Scan, is obtained by the surimposition of the femoral section passing through the trochlea at the level of the roman arch and the tibial section passing through the anterior tibial tuberosity.

This measure expresses the resultant of the lateral implantation of the anterior tibial tuberosity on the tibia and of the external rotation of the knee. The TT-TG was measured with the knee in extension. In the control subjects it is on average 12.7 mm, whereas in the OPI group it measures an average of 19.8 mm. There is a significant difference. The third principle factor is dysplasia of the quadriceps. There are two aspects of quadriceps dysplasia: 䢇 䢇

vastus medialis dysplasia the short quadriceps.

Vastus medialis dysplasia has been especially studied by Hughston and Insall. The vastus medialis obliquus ŽVMO., the lower part of the vastus medialis ŽVM. appears inserted at a distance from the patella and its fibres remain strictly vertical. It is therefore less efficient in stabilising the patella. Short quadriceps was studied by Dejour. This dysplasia evaluation is highly subjective clinically, but we attempted to determine it objectively by direct observation on a CT scan section passing through the summit of the patella, where the VMO is situated. The patellar tilt in extension is the angle formed by the transverse axis of the patella and the plane of the posterior condyles. This measurement, made with the quadriceps relaxed, is reliable, reproducible and constant for a given knee, even over several examinations. The values of the patellar tilt in extension, in the OPI group Žmean s 31.5⬚. and in the control group Žmean s 10⬚. are highly significantly different. The patellar tilt was over 20⬚ in 90% of cases in the OPI group. Secondary factors also appear to be very different in the control group and the OPI group but there is no threshold. Treatment Although rehabilitation may be very effective when there is an atrophy of the quadriceps, it can never compensate a true dysplasia of the quadriceps with a high patella and an excessive TT-TG. Our opinion is that one should operate true objective patellar instability with clinical symptoms especially when the patients are young before the cartilage damage. We recommend surgical treatment when the abnormalities are easy to correct, particularly one or several of the three principle factors. Sectioning of the lateral retinaculum is systematic but never isolated. It doesn’t modify patellar tilt in extension. The presence of an excessive TT-TG Žgreater than 20 mm. requires a medialization so that the TT-TG is reduced to 10 mm Žbelow this value the risk of hypercorrection is very high.. The tibial tubercule is advanced medially and or distally and fixed with 4.5 AO bicortical screws. A patellar tilt greater than 20⬚ requires an Insall type plasty of the vastus medialis. A high patella Žpatellar index greater than 1.2. necessitates lowering of the patella so that the patellar index is brought to a value of one. When needed, patellar tenodesis is associated with to restore its normal attachment site. This procedure reduces the functional length of patellar tendon. In cases of severe trochlear dysplasia, it is possible to perform a trochleoplasty. Elevation of the lateral facet is illogical and not a physiological procedure but it may prove efficacious, raising the lateral slope of the trochlea to counter the luxation. It can be indicated in the absence of bump. The most commonly observed problem is the filling in of the upper portion of the trochlea, but it is also the most difficult to correct. In very special case we proposed to deepen on the trochlea. Extensive release of the vastus lateralis is needed when dislocation is permanent. Femoral osteotomy is rarely indi-

Abstracts

85

cated. Rehabilitation program is needed with special care when tibial tubercule osteotomy has been performed. Results We reported during the 8th Journees ´ Lyonnaises du Genou, excellent results in terms of stability, but only good improvement of pain. Recurrence of patellar dislocation were mainly due to misdiagnosed patella alta. Discussion I just give you some results reported in literature concerning other treatments. Rehabilitation alone lead to 44% recurrence. Lateral release alone led to 40% recurrence. Fig. 1. Defect. MPFL reconstruction This gesture will be more evaluated in the next future. But reconstruction of the MPFL does not correct the factors of instability, we described except perhaps patellar tilt. Conclusion We can use reliable procedures but we need to know more about physiopathology to improve our indications and results. High flexion uni-compartmental arthroplasty C Dodd Oxford, UK The potential for ultimate knee replacement function has been available for the past 20 years. Uni-compartmental knee replacement surgery has provided superior function and range of motion when compared to total knee replacement, but it has suffered from being a technically more demanding procedure. Minimally invasive surgery with predictable instrumentation has brought about a renascence in uni-compartmental arthroplasty. This presentation describes the first 58 Oxford phase uni-compartmental arthroplasty with 1 year q follow-ups. There was a pre-operative mean, flexion angle of 123⬚, which improved to a mean of 135⬚ at one year. The American knee society score showed a pre-operative mean of 37 rising to 98 at 1 year for the knee section, and the pre-operative mean of 53 rising to, 1 year, a mean of 94 for the functional section. High flexion knee replacement has been possible now for a number of years. Revisions total knee arthroplasty with severe bone loss and soft tissue damage DA Dennis Denver, CO, USA I. Mild–moderate bone loss A. Revision bone deficiency classification ŽAORI ᎏ G. Engh. 1. Type I ᎏ metaphyseal bone intactrminor defects 2. Type II ᎏ metaphyseal bone damaged U A: one condyle U B: two condyles 3. Type III ᎏ majority of metaphyseal bone deficient ŽFigs. 1᎐3. B. Management 1. Prevention a. Tedious prosthesis removal b. Earlier revision if osteolysis ᎏ Pre-operative radiographs underestimate osteolysis

Fig. 2. A Defect.

Fig. 3. Defect.

2. Treatment options a. Cement Žwith or without screws. ᎏ Advantages 䢇 Economical 䢇 Easily contoured to osseous defect ᎏ Disadvantages 䢇 Premature radiolucent lines 䢇 Difficult to pressurize Žnon-contained defects. 䢇 2% shrinkage of PMMA during polymerization 䢇 Inferior load transfer under eccentric loading conditions 䢇 Thermal necrosis ᎏ Results 䢇 Ritter, J Arthroplasty, 1993 Ži. 47 TKArcementq screws Žii. 6.1-years follow-up Žiii. No cement failure or loosening

Abstracts

86

Lotke, CORR 1991 Ži. 33 TKArcement fillr7.1-year follow-up Žii. Defects - 20 mm and - 50% of condyle Žiii. 70% radiolucent linesrone failure ᎏ Recommendation ᎏ limit to small defects Ž5᎐10 mm. in elderly patients b. Prosthetic augmentation ᎏ Advantages 䢇 No disease transmission 䢇 No non-union or malunion 䢇 Favorable load transfer ᎏ Disadvantages 䢇 Sizershapes limited 䢇 Not usable in large defects ᎏ Results 䢇 Pagnano, CORR 1995 Ži. 24 TKAr67-month follow-up Žii. 54% radiolucent linesrno failures ᎏ Recommendation ᎏ consider for moderate sized Ž- 15 mm. non-contained defects c. Bone graft ᎏ Advantages 䢇 Economical Žlocal autograft. 䢇 Restores bone stock 䢇 Easily contoured to osseosus defects 䢇 Usable in large Ž) 15 mm. defects ᎏ Disadvantages 䢇 Disease transmission Žallograft. 䢇 Non-unionrmalunionrlate collapse ᎏ Results 䢇 Variable in primary TKA 䢇 Altechek, J. Arthroplasty 1989 Ži. 14 casesr4-years follow-up Žii. Local autograftrno failures 䢇 Laskin, CORR 1989 Ži. 26 Casesr5-years follow-up Žii. 27% non-unionr67% success ᎏ Recommendation ᎏ consider for larger defects and younger patients Žadditional revisions TKA likely.

ᎏ

䢇

II. Massive bone loss A. Treatment options 1. Arthrodesisrcustom TKAramputationrstructural allograft B. Structural allografting 1. Advantages a. Biological potential b. Bone stock restoration c. Cost Žrelative to custom TKA. d. Ligament reattachment Žvia bone block. 2. Disadvantages a. Disease transmission b. Non-unionrmalunionrlate collapse 3. Surgical technique a. Pre-operative planning ᎏ Rule out infection ᎏ Implant selection ᎏ ­ constraint may be required ᎏ Allograft selection 䢇 Femoral headrdistal femurrproximal tibia 䢇 Sizing critical 䢇 Fresh frozen ᎏ superior strength b. Surgical exposure ᎏ Extensile Often Required

c.

d.

e.

f.

Rectus sniprmodified V-Y quadriceps plastyr tibial tubercle osteotomy Allograft fixation ᎏ Must be rigid ᎏ Mechanically interlock with host bone ᎏ Diaphyseal engaging stems usually necessary ᎏ Screwsrplates occasionally necessary Prosthesis fixation ᎏ Cement to allograft ᎏ Diaphyseal engaging stems 䢇 Press-fit vs. cemented stem results similar Ligament reattachment ᎏ Sewing ligaments to allograft usually fails ᎏ Reattach via bone block technique Wound closure ᎏ occasionally tight Žtibia. ᎏ Relaxing incisionsrrotational flaps infrequently required

4. Results a. A. Harris, Rosenberg, et al. JBJS 1995 ᎏ 14 casesr43-months follow-up ᎏ 92.8% successful ᎏ One failure ᎏ non-unionrinfection b. Ghazavi, Gross et al. JBJS 1997 ᎏ 30 casesr50-months follow-up ᎏ 77% successful ᎏ Seven failures ᎏ infection Ž3., tibial loosening Ž2., allograft fracture Ž1., non-union Ž1. III. TKA stability A. Determined by: 1. Component articular geomet 2. Soft tissue supporting structures a. Ligamentsrcapsulermuscles B. Better obtained biologically than prosthetically 1. Constraint creates increased fixation stresses IV. TKA instability A. Classification 1. Medial-lateral 2. Anterior-posterior 3. Global 4. Symmetric vs. asymmetric B. Incidence 2᎐22% C. Etiologies 1. Ligament imbalance 2. Malalignment 3. Component failure 4. Faulty prosthetic design D. Symptoms ᎏ variable 1. Nonerpainrweaknessrgiving way E. Diagnosis 1. Clinical exam a. Measurable ligamentous laxity b. Hyperextension c. Posterior sag d. Effusion 2. Stress radiographs 3. Dynamic fluoroscopy F. Prevention 1. Balance and equalize flexion and extension gaps 2. Restoration of joint line ŽStiehl, J Arthroplasty 1995. a. 3.08 cm distal to medial epicondyle b. 2.53 cm distal to lateral epicondyle

Abstracts

G.

H.

I.

J.

3. Extension gap a. Determined by tibial and distal femoral resections 4. Flexion gap a. Determined by tibial and posterior femoral resections Symmetric extension instability 1. Usually secondary to: a. Excessive bone resectionrloss b. Soft tissue laxity ŽMCLrLCLrPCLrposterior capsule. 2. Results in varus-valgus laxity " recurvatum Asymmetric extension instability 1. Etiologies a. Error in femoralrtibial resection b. Asymmetric bone loss c. Collateral ligamentous imbalance ᎏ Under vs. over-release ᎏ Attenuation vs. disruption d. Tight PCL 2. Can usually tolerate mild lateral laxity a. Dynamic stabilizing effect of iliotibial band Symmetric flexion instability 1. Etiologies a. Undersized femoral component b. Excessive posterior tibial slope c. Attenuated vs. disrupted PCL 2. Accentuated with extensor mechanism insufficiency 3. Can result in dislocation Asymmetric flexion instability 1. Etiologies a. Error in femoral component rotation b. Collateral ligamentous imbalance c. Tight PCL 2. Can result in femoral condylar lift-off

V. TKA instability: management A. Non-operative 1. Mild instability often asymptomatic 2. Bracing Žproblems with compliance. 3. Physiotherapy B. Operative 1. Key is to balance and equalize flexionrextrension gaps and resoration of the joint line

Extension adequate

Extension loose

Extension tight

䢇

No changes

䢇

Augment distal femur

䢇

Flexion loose

䢇

Larger femoral component with posterior augmentation

䢇

Thicker tibial component

䢇

Flexion tight

䢇

Smaller femoral component 䢇Posterior tibial slope 䢇Consider PS

䢇

Flexion adequate

Resect distal femur 䢇Posterior release 䢇DrC posterior osteophytes Larger femoral component with posterior augmentation 䢇Resect distal femur

87

2. Treatment options a. Thicker tibial insert b. Angled tibial insert ŽShaw, J Arthroplasty 1992. ᎏ If associated malalignment c. Larger femoral component Žflexion instability . d. Increased prosthetic constraint e. Ligamentous advancement C. Flexion instability: treatment options 1. Thicker tibial insert a. Often fails ŽPagnano, Knee Society 1998. 2. More congruent insert 3. PCL substituting TKA Žmild instability . 4. Constrained TKA Žsevere instability . D. Dislocated PCL substituting TKA 1. Secondary to excessive flexion laxity 2. Incidence low Ž- 1᎐2%. 3. Mechanisms a. Excessive valgusrlateral releases Ždislocates in ‘figure four’ position. b. Hyperflexion 4. Treatment a. Closed reductionrcastrphysiotherapy in most b. Thicker PS insert c. Increase femoral component size d. Constrained TKA e. Ligamentous advancement E. Persistent instability: options 1. Constrained condylar TKA a. Not all are the same! ᎏ Variations in varus-valgus laxityrrotational laxity rpost height b. Indications ᎏ Advanced collateral ligamentous insufficiency ᎏ Inability to obtain flexion ᎏ extension gap balance c. Surgical technique ᎏ Must balance remaining soft tissues ᎏ Axial and rotational alignment critical ᎏ Diaphyseal engaging stems recommended to resist constraining forces d. Required less frequently if flexion-extension balance obtained and joint line restored e. Survivorship inversely proportional to level of prosthetic constraint! 2. Linked hinge TKA a. Rarely required b. Often associated with premature failure c. Indications ᎏ Global instability ᎏ Uncontrolled hyperextension ᎏ Tumor resection ᎏ Comminutedrosteopenic supracondylar femoral fracture 3. Ligamentous advancement ŽKrackow, JBJS-A 1990. a. MCL vs. LCL advanced at femoral origin b. Technically demanding ŽKrackow locking stitch, JBJSA 1986. c. Protect repair Žbrace vs. constrained TKA. d. Limited cases reported Bibliography — instability

Smaller femoral component with distal augmentation 䢇Consider PS

Thinner tibial component 䢇Increase tibial resection 䢇

1. Cohen B, Constant CR. Subluxation of the posterior stabilized total knee arthroplasty. J Arthroplasty 1992;7:161. 2. Edwards E, Miller J, Chan KH. The effect of post-operative collateral ligament laxity in total knee arthroplasty. Clin Orthop 1988;236:44᎐51.

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Abstracts

3. Fehring TK, Valadie AJ. Knee instability after total knee arthroplasty. Clin Orthop 1994;299:157. 4. Galinat BJ, Vernace JV, Booth RE Jr, Rothman RH. Dislocation of the posterior stabilized total knee arthroplasty: a report of two cases. J Arthroplasty 1988;2:363. 5. Gebhard JS, Kilgus DJ. Dislocation of a posterior stabilized total knee prosthesis: a report of two cases. Clin Orthop 1990;254:225᎐229. 6. Griffin WI, Fehring TK, Valadie A. Revision of the unstable total knee arthroplasty. In: Engh GA, Rorabeck CH, editors. Revision total knee arthroplasty Žchapter 18.. Baltimore: Williams and Wilkins, 1997:340᎐351. 7. Healy WL, Lemos DW. Proximal medial collateral ligament advancement with bone plug recession for treatment of severe valgus deformity in total knee arthroplasty. Presented at the Annual Meeting of the Knee Society. New Orleans ŽLA, USA.: March 22, 1998. 8. Hofmann AA, Tkach TK, Evanich CJ, Camargo MP, Scott D. Posterior stabilization using an ultracongruent polyethylene insert in total knee arthroplasty. Presented at the Annual Meeting of the Knee Society. San Francisco ŽCA, USA.: February 16, 1997. 9. Kester MA, Cook SD, Harding AF, et al. An evaluation of the mechanical failure modalities of a rotating hinged knee prosthesis. Clin Orthop 1988;228:156. 10. Kocmond JH, Delp SL, Stern SH. Stability and range of motion of Insall᎐Burstein condylar prostheses, a computer simulation study. J Arthroplasty 1995;10:388. 11. Krackow KA, Thomas SC, Jones LC. A new stitch for ligament-tendon fixation: brief note. J Bone Joint Surg 1986;68A:764᎐766. 12. Krackow KA, Weiss AP. Recurvatum deformity complicating performance of total knee arthroplasty. A brief note. J Bone Joint Surg 1990;72A:268. 13. Krackow KA: Deformity. In: Krackow KA, editor. The technique of total knee arthroplasty Žchapter 8.. St. Louis: CV Mosby, 1990:249᎐372. 14. Lombardi AV, Mallory TH, Vaughn BK, et al. Dislocation following primary posterior-stabilized knee arthroplasty. J Arthroplasty 1993;8:633᎐639. 15. McPherson EJ, Vince KG. Breakage of a total condylar III knee prosthesis. J Arthroplasty 1993;8:561. 16. Pagnano MW, Hanssen AD, Lewallen DG, Stuart MJ. Flexion instability after primary posterior-cruciate retaining total knee arthroplasty. Presented at the Annual Meeting of the Knee Society. New Orleans ŽLA, USA.: March 22, 1998. 17. Pritsch M, Fitzgerald RH Jr, Bryan RS. Surgical treatment of ligamentous instability after total knee arthroplasty. Arch Orthop Trauma Surg 1984;102:154᎐158. 18. Rand JA, Chao EY, Stauffer RN. Kinematic rotating-hinge total knee arthroplasty. J Bone Joint Surg 1987;69A:489. 19. Ritter MA, Meding JB. Anterior displacement. Its effects on instability and radiolucency in total knee replacements. Clin Orthop 1986;208:259᎐265. 20. Sculco TP. Total condylar III prosthesis in ligament instability. Orthop Clin North Am 1989;20:221᎐226. 21. Sharkey PF, Hozack WJ, Booth RE Jr, Balderston RA, Rothman RH. Posterior dislocation of total knee arthroplasty. Clin Orthop 1992;267:128. 22. Shaw JA. Angled bearing inserts in total knee arthroplasty. J Arthroplasty 1992;7:211. 23. Shoemaker SC, Markolf KL, Finerman GA. In vitro stability of the implanted total condylar prosthesis. Effects of joint load and of sectioning the posterior cruciate ligament. J Bone Joint Surg 1982;64A:1201᎐1213. 24. Stiehl JB, Abbot BD. Morphology of the transepicondylar axis

and its application in primary and revision total knee arthroplasty. J Arthroplasty 1995;10:785᎐789. 25. Vince KG, Berkowitz R, Spitzer A. Collateral ligament reconstruction in difficult primary and revision total knee arthroplasty. Presented at the Annual Meeting of the Knee Society. San Francisco ŽCA, USA.: February 16, 1997. 26. Warren PJ, Olanlokun TK, Cobb AG, Walker PS, Iverson BF. Laxity and function in knee replacement. A comparative study of three prosthetic designs. Clin Orthop 1994;305:200᎐208. 27. Whiteside LA, Kasselt MR, Haynes DW. Varus-valgus and rotational stability in rotationally unconstrained total knee arthroplasty. Clin Orthop 1987;219:147᎐157. Bibliography — bone loss

1. Aglietti P, Buzzi R, Scrobe F. Autologous bone grafting for medial tibial defects in total knee arthroplasty. J Arthroplasty 1991;6Ž4.:287᎐294. 2. Altchek P, Sculco TP, Rawlins B. Autogenous bone grafting for severe angular deformity in total knee arthroplasty. J Arthroplasty 1989;4Ž2.:151᎐155. 3. Brand MG, Daley RJ, Ewald FC, Scott RD. Tibial tray augmentation with modular metal wedges for tibial bone stock deficiency. Clin Orthop 1989;248:71᎐79. 4. Brooks PJ, Walker PS, Scott RD. Tibial component fixations in deficient tibial bone stock. Clin Orthop 1984;184:302. 5. Chandler HP. Revision total knee arthroplasty-structural bone grafting: when and how. Orthopedics 1996;19Ž9.:797᎐799. 6. Chandler HP. Structural bone grafting about the knee. Orthopedics 1998;21Ž9.:1044᎐1045. 7. Chen F, Krackow KA. Management of tibial defects in total knee arthroplasty. Clin Orthop 1994;305:249᎐287. 8. Dennis DA. Repairing minor bone defects: Augmentation and autograft. Orthopedics 1998;21Ž9.1036᎐1038. 9. Dennis DA. Structural allografting in revision total knee arthroplasty. Orthopedics 1994;17Ž9.:849᎐851. 10. De Waal Malefijt MC, van Kampen A, Slooff TJ. Bone grafting in cemented knee replacement. Forty-five primary and secondary cases followed for 2᎐5 years. Acta Orthop Scand 1995;66Ž4.:325᎐328. 11. Dorr LD, Ranawat CS, Sculco TA, McKaskill B, Orisek BS. Bone graft for tibial defects in total knee arthroplasty. Clin Orthop 1986;205:153᎐165. 12. Dorr LD. Bone grafts for bone loss with total knee replacement. Orthop Clin of N Am 1989;20Ž2.:179᎐187. 13. Elia EA, Lotke PA. Results of revision total knee arthroplasty associated with significant bone loss. Clin Orthop 1991;271:114᎐121. 14. Engh GA. The use of bone grafts in difficult primary and revision total knee arthroplasty. Orthop Review 1990;ŽOct. Suppl..:64᎐70. 15. Engh GA, Parks NL. The management of bone defects in revision total knee arthroplasty. Instr Course Lect 1997;46:227᎐236. 16. Engh GA, Ammeen DJ. Classification and pre-operative radiographic evaluation: the knee. Orthop Clin N Am 1998;29Ž2.:205᎐217. 17. Garbuz DS, Masri BA, Czitrom AA. Biology of allografting. Orthop Clin N Am 1998;29Ž2.:199᎐204. 18. Ghazavi MT, Stockley I, Yee G, Davis A, Gross AE. Reconstruction of massive bone defects with allograft in revisions total knee arthroplasty. J Bone Joint Surg 1997;79-AŽ1.:17᎐25. 19. Gross AE, Allen G, Lavoie G. Revision arthroplasty using allograft bone. Instr Course Lect 1993;42:363᎐380. 20. Gross AE. Revision total knee arthroplasty of bone rafts vs. implant supplementation. Orthopedics 1997;20Ž9.:843᎐844.

Abstracts 21. Haas SB, Insall JN, Montgomery W, Windsor RE. Revision total knee arthroplasty with the use of modular components with stems inserted without cement. J Bone Joint Surg 1995;77ŽA.:1700᎐1707. 22. Harris AI, Poddar S, Gitelis S, Sheinkop MB, Rosenberg AG. Arthroplasty with a composite of an allograft and a prosthesis for knee with severe deficiency of bone. J Bone Joint Surg 1995;77-AŽ3.:373᎐386. 23. Johnson R, Sampath SAC, Elloy MA. Use of bone cement for medial tibial defects in total knee replacements: the results with a conical tibial component. Int Orthop 1995;3Ž2.:147᎐151. 24. Kraay MJ, Goldberg VM, Figgie MP, Figgie HE III: Distal femoral replacement will allograftrprosthetic reconstruction for treatment of supracondylar fractures in patients with total knee arthroplasty. J Arthroplasty 1992;7Ž1.:7᎐16. 25. Kress KJ, Scuderi GR, Windsor RE, Insall JN. Treatment of non-unions about the knee utilizing custom total knee arthroplasty with press-fit intramedullary stems. J Arthroplasty 1993;8Ž1.:49᎐55. 26. Laskin RS. Total knee arthroplasty in the presence of large bony defects of the tibia and marked knee instability. Clin Orthop 1989;248:66᎐70. 27. Lotke PA, Wong RY, Ecker ML. The use of methylmethacrylate in primary total knee replacements with large tibial defects. Clin Orthop 1991;270:288᎐294. 28. Mnaymneh W, Emerson RH, Borja F, Head WC, Malinin TI. Massive allografts in salvage revisions of failed total knee arthroplasty. Clin Orthop 1990;260:144᎐153. 29. Mow CS, Wiedel JD. Structural allografting in revision total knee arthroplasty. J Arthroplasty 1996;11Ž3.:235᎐241. 30. Pagnano MW, Trousdale RT, Rand JA. Tibial wedge augmentation for bone deficiency in total knee arthroplasty. A followup study. Clin Orthop 1995;321. 31. Parks NL, Engh GA. The Ranawat Award: Histology of nine structural bone grafts used in total knee arthroplasty. Clin Orthop 1997;345:17᎐23. 32. Rand JA. Bone defiency in total knee arthroplasty. Use of metal wedge augmentation. Clin Orthop 1991;271:63᎐71. 33. Rand JA. Revision total knee arthroplasty using the condylar III prosthesis. J Arthroplasty 1991;6Ž3.:279᎐284. 34. Ritter MA. Screw and cement fixation of large defects in total knee arthroplasty. J Arthroplasty 1986;1Ž2.:125᎐129. 35. Ritter MA, Keating EM, Faris PM. Screw and cement fixation of large defects in total knee arthroplsty: a sequel. J Arthroplasty 1993;8Ž1.:63᎐65. 36. Robinson EJ, Mulliken BD, Bourne RB, Rorabeck CH, Alvarez C. Catastrophic osteolysis in total knee replacement. Clin Orthop 1995;321:98᎐105. 37. Rorabeck CH, Smith PN. Results of revision total knee arthroplasty in the face of significant bone deficiency. Orthop Clin N Am 1998;29Ž2.:361᎐371. 38. Rosenberg AG: The use of bone grafting for managing bone defects in complex total knee arthroplasty. Am J Knee Surg 1997;10Ž1.:42᎐48. 39. Scott RD: Bone loss: prosthetic and augmentation method. Orthopedics 1995;18Ž9.:923᎐926. 40. Scuderi GR, Insall JN, Haas SB, Becker-Fluegel MW, Windsor RE. Inlay autogeneic bone grafting of tibial defects in primary total knee arthroplasty. Clin Orthop 1989;248:93᎐97. 41. Sculco TP, Choi JC. The role and results of bone grafting in revision total knee replacement. Orthop Clin N Am 1998;29Ž2.:339᎐346. 42. Stockley I, McAuley JP, Gross AE. Allograft reconstruction in total knee arthroplasty. J Bone Joint Surg 1992;74BŽ3.:393᎐397.

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43. Stulberg SD. Managing bone loss with augmentation. Orthopedics 1997;20Ž9.:845᎐847. 44. Tsahakis PJ, Beaver WB, Brick GW. Technique and results of allograftreconstruction in revision total knee arthroplasty. Clin Orthop 1994;303:86᎐94. 45. Whiteside LA: Morselized allografting in revision total knee arthroplasty. Orthopedics 1998;21Ž9.:1041᎐1043. 46. Whiteside LA. Bone grafting in revision cementless total knee arthroplasty. Instr Course Lect 1993;42:397᎐403. 47. Wilde AH, Schickendantz MS, Stulberg BN, Go RT. The incorporation of tibial allografts in total knee arthroplasty. J Bone Joint Surg 1990;72-AŽ6.:815᎐824. 48. Windsor RE, Insall JN, Sculso TP. Bone grafting of tibial defects in primary and revision total knee arthroplasty. Clin Orthop 1986;205:132᎐137. Normal tibio-femoral kinematics — an ‘interventional’ MRI study of flexion of the weight-bearing living knee A Williams London, UK Using the St Mary’s ‘interventional’ MRI scanner, 10 subjects with asymptomatic knees were studied. Their knees were scanned weight-bearing from hyperextension and hence, whilst squatting at 10⬚ increments through to full deep flexion. Imaging planes were obtained in the mid-medial and mid-lateral compartments of the tibio-femoral joints. A special device maintains the same plane of scanning between increments of movement. Distances between fixed reference points on the femoral condyles and the posterior tibial cortex were used to measure relative motion of the femur on the tibia. The lateral femoral condyle moves posteriorly on the tibia during flexion from hyperextension to 120⬚ by 22 mm. From 120⬚ to full deep flexion there is another 9 mm of posterior translation, with the lateral femoral condyle almost subluxing off the tibia. Medially, there is no significant posterior movement of the femoral condyle until 120⬚. Thereafter, the medial femoral condyle moves 8 mm posteriorly. The differential medio-lateral motion to 120⬚ knee flexion equates to external femoral rotation during knee flexion Žtibial internal rotation. and not bodily femoral ‘roll-back’. Flexion over 120⬚ to deep flexion was accompanied by equal medial and lateral posterior displacement, i.e. the motion is no longer rotation about a longitudinal axis through the tibia. In full deep flexion the medial condyle lifts away Ži.e. moves superiorly. from the tibia Ž1.66 mm.. Conclusion The measurements of relative tibio-femoral movement confirmed our previous study findings to 90⬚, and are consistent with previous work on full flexion in the unloaded knee studied by MRI ŽNakagawa et al... Although the tibio-femoral joint surface contact point moves posteriorly during knee flexion the medial femoral condyle does not bodily ‘roll-back’ as commonly believed. This apparent paradox is possible due to the shapes of the tibio-femoral articular surfaces. The mechanism of deep flexion is clearly different from that to 120⬚. Laterally, there is extreme posterior displacement of the femoral condyle on the tibia. We have shown a different kinematic mechanism in deep flexion above 120⬚. In such positions the posterior horn of the medial meniscus lies compressed between the femoral and tibial joint surfaces perhaps providing a fulcrum. This explains the risk of posterior horn tears of the medial meniscus from deep flexion. In view of the kinematics which we have shown to occur, current total knee replacement designs plus the limitations of available biomate-

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rials, may fail to achieve ranges of flexion above 120⬚ whilst maintaining stability and longevity. A novel solution may be needed.

lateralization of the tibial tubercle if external tibial rotation occurs with increasing knee flexion.

Kinematics for the common man DA Dennis, RD Komistek Denver, CO, USA

Femoral condylar lift-off Femoral condylar lift-off following TKA was commonly observed, occurring in 70% of subjects implanted with a fixed bearing PCR TKA, 80% of those with a fixed bearing PCS TKA, and greater than 90% of subjects with a mobile bearing TKA. Lift-off most commonly occurred during the midstance phase of gait and at flexion ranges greater than 60⬚. Adverse effects of femoral condylar lift-off include premature polyethylene wear and component loosening secondary to eccentric loading conditions. Important implant design features to accommodate lift-off conditions include increased polyethylene coronal conformity and tibial tray metal backing to reduce load transmission to subchondral bone.

In vivo knee kinematics Žanteroposterior translation, axial rotation, femoral condylar lift-off and range of motion. were determined in multiple studies of the normal knee and in subjects implanted with both fixed and mobile bearing total knee arthroplasty ŽTKA.. All subjects were analyzed under video fluoroscopic surveillance while performing level gait and a deep knee bend maneuver. Fluoroscopic videotapes were then analyzed using a computer model fitting technique. Anteroposterior translation In the normal knee during gait, a small amount of posterior translation of femorotibial contact Žposterior femoral rollback. typically occurs laterally Žaverage, 4.2 mm. while minimal translation occurs medially. During a deep knee bend ŽDKB. activity, posterior femoral rollback laterally was increased Žaverage, 14.1 mm. while medial translation remained minimal Žaverage, 1.5 mm.. Therefore, on average, a medial pivot kinematic pattern was observed although this pattern is not present in all normal knees tested. Following both fixed and mobile bearing TKA, minimal amounts of anteroposterior translation were observed both medially and laterally during gait. No dramatic differences were observed between posterior cruciate retaining ŽPCR. or substituting ŽPCS. TKA during gait since the cam and post mechanism of the PCS TKA is not typically engaged during this activity. Intersubject variability of anteroposterior translation patterns was less Žminimal. in mobile bearing vs. fixed bearing TKA designs during gait. This was attributed to the increased sagittal conformity allowed in mobile bearing TKA. During a DKB activity, high variability in anteroposterior translational patterns was observed in all fixed and mobile bearing TKA designs which lacked a posterior cruciate stabilizing mechanism. In contrast to the normal knee, where posterior femoral rollback occurs during deep flexion activities, a paradoxical anterior shift of femorotibial contact was commonly observed during deep flexion, particularly in subjects implanted with a fixed bearing PCR TKA. Following PCS TKA, posterior femoral rollback of the lateral femoral condyle routinely occurred with minimal variability of femorotibial contact patterns due to routine engagement of the cam and post mechanism during deep flexion activities. Potential adverse effects of the paradoxical anterior shift of femorotibial contact position during deep flexion observed in nonstabilized TKA designs include: Ž1. loss of weight-bearing knee flexion due to anteriorization of the axis of knee flexion; Ž2. reduced quadriceps efficiency secondary to a reduction in quadriceps lever arm; and Ž3. accelerated polyethylene wear due to increased shear forces created during anterior femoral translation. Axial rotation During gait and a DKB activity, subjects having a normal knee experienced a ‘screw-home’ axial rotation pattern Žtibial internal rotation with increasing knee flexion.. Following TKA, reduced axial rotational values were observed in all designs tested ŽTable 1.. Reverse screw-home axial rotational patterns and high variability among subjects were noted in all TKA groups, particularly in non-stabilized designs. Reverse axial rotation is potentially detrimental, enhancing the risk of patellofemoral instability due to

Range of motion Range of motion following TKA is reduced in all designs tested when compared to the normal knee ŽTable 2.. Additionally, testing under weight-bearing conditions results in less flexion than when testing under passive non-weight-bearing conditions. Range of motion following TKA was more determined by articular condylar geometry than by the presence of bearing mobility. Greatest knee flexion was observed in PCS TKA, attributed to the posterior femoral rollback, which was routinely observed following cam-post engagement. Summary Various alterations in normal knee kinematic patterns Žparadoxical anterior femoral translation, reverse axial rotation, and femoral condylar lift-off. are commonly observed following TKA in both fixed and mobile bearing designs. The authors believe bearing mobility will dominate future TKA designs due to increased articular conformity and reduced polyethylene stress allowed with these designs. New designs should focus on better control of bearing mobility patterns to reduce the incidence of abnormal kinematic motions observed in present fluoroscopic evaluations.

Table 1. Average axial rotation values for subjects having various knee types Knee type

Gait Ždegrees.

Deep knee bend Ždegrees.

Normal 4.4 Žy1.8 to 7.0. 16.8 Ž2.1᎐27.1. PS fixed bearing y0.1 Žy5.4 to 10.0. 10.4 Ž2.9᎐20.1. PCR fixed bearing 0.1 Žy11.2 to 7.5. 1.9 Žy9.7 to 7.9. LCS rotating platform 2.1 Žy1.3 to 6.3. 2.9 Žy3.9 to 8.6. LCS AP glide 0.1 Žy26.6 to 9.9. y1.1 Žy12.4 to 4.1. Table 2. Maximum condylar lift-off values for subjects having various knee types Knee type

Gait Žmm.

Deep knee bend Žmm.

Normal PS fixed bearing PCR fixed bearing LCS rotating platform LCS AP glide LCS RP PS S-ROM PS

2.6 1.3 1.4 2.2 3.3 2.1 nra

3.5 3.1 2.2 1.8 2.1 3.3 2.4

Abstracts

91

In vivo fluoroscopic evaluation of kinematics after total knee arthroplasty DA Dennis Denver, CO, USA I. Methods A. In vivo weight-bearing fluoroscopic analysis B. Automated three-dimensional model fitting technique 1. CAD models fit Žoverlaid. over fluoroscopic images 2. Femorotibial contact points determined C. Various kinematic patterns studied 1. Anteroposterior femorotibial translation 2. Femoral condylar lift-off 3. Axial femorotibial rotation 4. Range of motion D. Activities studied 1. Deep knee bend ŽDKB. 2. Gait ŽFig. 4. II. Anteroposterior femorotibial translation A. Fixed bearing posterior cruciate retaining ŽPCR. TKA 1. Contact posterior in extension 2. Paradoxical anterior femoral translation in deep flexion not uncommon 3. Posterior femoral rollback uncommon 4. High variability in contact pathways B. Fixed bearing posterior cruciate substituting ŽPS. TKA 1. Posterior femoral rollback routinely occurs in DKB a. Less than in the normal knee 2. Consistent contact pathways C. Meniscal bearing TKA 1. Very similar to fixed bearing PCR TKA 2. Highly variable contact pathways D. Rotating platform TKA 1. Minimal anteroposterior translation a. Increased sagittal conformity b. Contact midline throughout flexion 2. High variability among subjects E. Rotating platform PS TKA ŽS-ROM. 1. Posterior femoral rollback routinely occurs in DKB 2. Minimal variability 3. Similar to fixed bearing PS TKA

Fig. 5. PS TKA demonstrating condylar lift-off. D. Most commonly seen in deep flexion Ž60᎐90⬚. in all designs ŽFig. 5.IV. Axial femorotibial rotation A.

Normal-tibial internal rotation with increasing flexion Žscrew᎐home mechanism. B. Fixed bearing PCR TKA 1. A¨ erage rotation Ž0᎐90⬚.: 0.6⬚ 2. Reverse screw-home rotation common at 60᎐90⬚ 3. Highly variable rotational patterns C. Fixed bearing PS TKA 1. A¨ erage rotation Ž0᎐90⬚.: 9.7⬚ 2. Highly variable rotational patterns D. Rotating platform TKA 1. Analyzed in gait 2. A¨ erage rotation Žheel strike ª toe-off.: 0.1⬚ 3. Reverse screw-home pattern: 65% 4. Highly variable rotational patterns a. Minimum: 0.1⬚ b. Maximum: 9.5⬚ V. Range of motion A. Abnormal kinematics often observed only under weight-bearing conditions B. Tested under passivernon-weight bearing vs. activerweightbearing conditions

Type

Nonweightbearing

Weightbearing

Normal Fixed PCR TKA Fixed PS TKA Meniscal bearing Rotating platform

139 123 127 121 108

135 103 113 100 99

III. Femoral condylar lift-off A. Fixed bearing PCR TKA-70% incidence 1. Primarily lateral 2. ACL absentrPCL intact B. Fixed bearing PS TKA-80% incidence 1. Both medial and lateral C. Rotating platform TKA-85% incidence 1. 41% medialr59% lateral

Fig. 4. Automated model fitting.

IV. Summary A. Better anteroposterior translation patterns observed with PS vs. PCR TKA 1. More reproduciblerbetter posterior B. Femoral rollback femoral condylar lift-off common in all designs 1. Most common at 60᎐90⬚ flexion 2. Risks edge loading 3. Coronal conformity important to reduce loads C. In vivorweight-bearing kinematic patterns are not dramatically different between fixed and mobile bearing TKA 1. Exception ᎏ rotating platform in gait which demonstrated minimal average anteroposterior translation

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B. Range of motion ᎏ more determined by implant geometry than bearing mobility Bibliography

1. Stiehl JB, Komistek RD, Dennis DA, Paxson RD, Hoff WA. Fluoroscopic analysis of kinematics after posterior-cruciate retaining knee arthroplasty. J Bone Joint Surg 1995; 77B:884᎐889. 2. Stiehl JB, Komistek RD, Dennis DA, Paxson RD. Kinematic analysis of the knee following posterior cruciate retaining total knee arthroplasty using fluoroscopy. Orthop Trans 1995;19:462. 3. Dennis DA, Komistek RD, Hoff WA, Gabriel SM. In vivo knee kinematics derived using an inverse perspective technique. Clin Orthop 1996;331:107᎐117. 4. Dennis DA, Komistek RD, Cheal E, Stiehl JB, Walker SA. In vivo femoral condylar lift-off in total knee arthroplasty. Orthop Trans 1997᎐1998;21:1112. 5. Dennis DA, Komistek RD, Cheal EJ, Walker SA, Stiehl JB. In vivo femoral condylar lift-off in total knee arthroplasty. J Bone Joint Surg 2001;83-B:Žin press.. 6. Stiehl JB, Dennis DA, Komistek RD, Keblish PA. In vivo kinematic analysis of a mobile bearing total knee prosthesis. Clin Orthop 1997;345:60᎐66. 7. Dennis DA, Komistek RD, Colwell CE, Ranawat SC, Scott RD, Thornhill TS, Lapp MA. In vivo anteroposterior femorotibial translation of total knee arthroplasty: a multicenter analysis. Clin Orthop 1998;356:47᎐57. 8. Dennis DA, Komistek RD, Stiehl JB, Walker SA, Dennis K. Range of motion following total knee arthroplasty: the effect of implant design and weight-bearing conditions. J Arthroplasty 1998;13Ž7.:748᎐752. 9. Dennis DA, Komistek RD, Stiehl JB, Anderson DT, Shoureshi RA. In vivo determination of TKA kinematics during treadmill gait. Read at the Annual Meeting of the Orthopaedic Research Society. Anaheim ŽCA, USA.: February 3, 1999. 10. Stiehl JB, Dennis DA, Komistek RD, Crane H. In vivo determination of condylar liftoff and screw home in a mobile bearing total knee arthroplasty. J Arthroplasty 1999;14: 293᎐299. 11. Callaghan JJ, Insall JN, Greenwald AS, Phil D, Dennis DA, Komistek RD, Murray DW, Bourne RB, Rorabeck CH, Dorr LD. Mobile-bearing knee replacement. J Bone Joint Surg 2000;82-A:1020᎐1041. 12. Komistek RD, Dennis DA. Fluoroscopic analysis of total knee replacement. Surgery of the knee, 3rd ed., vol. 2. New York: Churchill Livingstone, 2001:1695᎐1704. Anatomy and biomechanics of the posterior cruciate ligament AA Amis Imperial College, London, UK The PCL links the medial femoral condyle to the posterior aspect of the proximal tibia. The tibial attachment is relatively compact, and is located centrally on the posterior intercondylar shelf, between the posterior horns of the menisci. The femoral attachment is extensive, and covers most of the lateral face of the medial condyle, plus most of the anterior part of the roof of the intercondylar notch. The fibres attach up to the borders of the articular surfaces, and this occupies some 30᎐35 mm in an AP extent. Thus, the fibres fan out from the tibia to the femur. The femoral intercondylar notch is not symmetrical, and the PCL occupies the majority of it, leaving a relatively narrow space laterally for the ACL.

The main bulk of the PCL fibres forms an ‘anterolateral bundle’, that passes in a sagittal plane from the tibia to the anterior roof of the femoral intercondylar notch. This bundle is slack when the knee is extended. The ‘posteromedial bundle’ attaches to the medial condyle, and is tight in full knee extension. Across the mid-range of knee flexion, the anterolateral bundle is tight and the posteromedial bundle slack. The posteromedial bundle retightens in deep flexion w1x. The PCL is the strongest ligament in the knee, and most of that strength is in the anterolateral bundle w2x. The main function of the PCL is to resist posterior tibial draw. In extension, the knee is stabilised primarily by the posterolateral structures, not the PCL. This means that an isolated PCL reconstruction will fail to stabilise a knee that is unstable in extension, and an additional posterolateral reconstruction procedure is essential. The anterior bulk of the PCL is the primary restraint in mid-flexion, and is ruptured by ‘dashboard’ injuries. The posteromedial bundle is the primary restraint in deep knee flexion w3x. Because of the distinct pattern of PCL length changes with knee flexion, an isometric PCL reconstruction does not fit in with the behaviour of the rest of the knee. A graft placed into the anterior notch roof reproduces the bulk of the PCL and gives stability across most of the range of flexion. Adding a second bundle to the reconstruction may be justified if needing stability in deep knee flexion w4x. The central location of the PCL means that it cannot have a significant role in resisting tibial internal-external rotation, and isolated rupture does not increase this laxity. Increased external tibial rotation normally arises from posterolateral damage. As well as controversy regarding PCL reconstruction; should it be done if isolated? Is a double-bundle reconstruction justified? There are other aspects arising from increasing knowledge of the posterolateral structures and meniscofemoral ligaments, that may suggest further surgical complications if evidence to support this is obtained. References

1. Amis AA. Anatomy and biomechanics of the PCL. Sports Med Arthroscop Rev 1999;7:225᎐234. 2. Race A, Amis AA. The mechanical properties of the two bundles of the human PCL. J Biomech 1994;27:12᎐24. 3. Race A, Amis AA. Loading of the two bundles of the PCL: an analysis of bundle function in AP drawer. J Biomech 1996;29:873᎐879. 4. Race A, Amis AA. PCL reconstruction: in vitro biomechanical comparison of ‘isometric’ vs. single and double-bundled ‘anatomic’ grafts. J Bone Jt Surg 1998;80B:1733᎐1739. Physical signs — PCL and posterolateral corner RL Allum Windsor, UK Firstly, it is appropriate to briefly consider the anatomy and biomechanics as an understanding of these will enable a logical approach to be made to the physical signs. Anatomy This is variable and there are three layers. There are dynamic and static stabilisers. The dynamic stabilisers are: 䢇 䢇

Biceps Lateral head of gastrocnemius

Abstracts The static stabilisers are:

䢇 䢇

䢇 䢇 䢇

䢇 䢇 䢇 䢇 䢇

Iliotibial band Lateral collateral ligament Popliteus ` Arcuate ligament ` Arcuate ligament complex: ` Arcuate ligament ` Lateral collateral ligament Popliteus Lateral head of gastrocnemius Popliteofibular ligament Fabellofibular ligament Lateral meniscus

Biomechanics The function of ligaments can be assessed by selective cutting studies. Abnormal motion is measured after division of ligaments in isolation and in combination. In the knee the important planes of laxity are anteriorrposterior translation, internalrexternal rotation and varusrvalgus rotation. Instability occurring in the same direction as the applied force is termed primary and in a different direction is termed coupled. Posterior cruciate ligament The predominant instability is primary posterior translation at 90⬚ of flexion. There is also a minor degree of primary external rotation. Posterolateral corner The instabilities are: 䢇 䢇 䢇 䢇

Primary posterior translation maximum at 30⬚ flexion Primary varus rotation maximum at 30⬚ flexion Primary external rotation maximum at 30⬚ flexion Coupled external rotation with an anterior force maximum at 30⬚ flexion

Combined posterior cruciate and posterolateral corner injuries are synergistic with a significant increase in: 䢇 䢇 䢇 䢇

Primary posterior translation Primary varus rotation Primary external rotation Coupled external rotation

History The injury mechanism is high energy and the forces are posterior, hyperextension, varus and external rotation. Posterior cruciate and posterolateral insufficiency may cause instability on everyday activities as opposed to patients with a torn anterior cruciate ligament where instability normally occurs during sporting activities involving turning, cutting, accelerationrdeceleration, change of direction or jumping. Physical signs The diagnostic tests are: 䢇 䢇 䢇 䢇 䢇 䢇

Posterior drawer at 30⬚ flexion Posterior drawer at 90⬚ flexion Quadriceps active External rotation recurvatum Posterolateral external rotation drawer at 30⬚ flexion Posterolateral external rotation drawer at 90⬚ flexion

䢇 䢇 䢇

93 Tibial external rotation Ždial. at 30⬚ flexion Tibial external rotation Ždial. at 90⬚ flexion Varus stress at 0⬚ flexion Varus stress at 30⬚ flexion Reversed pivot shift

The following tests are specific for the posterior cruciate ligament: 䢇 䢇

Posterior drawer at 90⬚ flexion Quadriceps active The following tests are specific for the posterolateral corner:

䢇 䢇 䢇 䢇 䢇

External rotation recurvatum Posterolateral external rotation drawer at 30⬚ flexion Tibial external rotation Ždial. at 30⬚ flexion Varus stress at 30⬚ flexion Reversed pivot shift

Varus thrust can also be of importance and may indicate the need for tibial osteotomy. This table summarises the physical signs in posterior cruciate, posterolateral corner and combined instabilities. Test

PCL

PLC

PCLr PLC

Posterior drawer at 30⬚ flexion Posterior drawer at 90⬚ flexion Quadriceps active External rotation recurvatum Posterolateral ER drawer at 30⬚ flexion Posterolateral ER drawer at 90⬚ flexion Tibial external rotation Ždial. at 30⬚ flexion Tibial external rotation Ždial. at 90⬚ flexion Varus stress at 0⬚ flexion Varus stress at 30⬚ flexion Reversed pivot shift

" q q ᎐ ᎐ " ᎐ " ᎐ ᎐ ᎐

q ᎐ ᎐ q q " q q " q q

qq qq q qq qq qq qq qq q qq qq

Plain radiology in the PCL deficient knee G. Puddu Rome, Italy The purpose of this paper is to present a radiological method of diagnosis and evaluation of posterior instability using the patellofemoral axial view. During a period of 22 months, we performed clinical and radiological assessments on 20 patients Žsix acute and 14 chronic. with isolated posterior instability caused by posterior cruciate ligament ŽPCL. rupture, and on 20 patients with normal knees. The radiological examination included stress radiographs using the Telos device as well as a modification of the routine axial patellofemoral view. Both diagnosis and quantification of the posterior tibial translation was possible in all cases by measuring, on the axial view, the distance between the anterior edge of the tibial plateau and the centre of the femoral groove Žtrochlea.. Clinical examination, conventional radiography, KT-1000 arthrometry, stress radiography at 90⬚ and at 20⬚ of flexion, and magnetic resonance imaging all assist in diagnosing a PCL tear. This new radiographic technique is simple, fast, and consistently effective both in patients with acute and those with chronic PCL tears, as well as in those who have undergone PCL reconstruction.

Abstracts

94 PCL injuries — conservative management B Tietjens Auckland, New Zealand

The natural history of PCL injuries has not been well documented in the published literature. Some PCL injuries go unrecognised and the outcome is quite benign. Strictly isolated PCL injuries with mild to moderate laxity Ž- 10 mm posterior laxity. will do well with non-operative management. For more severe PCL injuries with combined instability, the prognosis is poor and operative treatment is recommended. Different injury mechanisms may produce different patterns of pathology. In sport the ‘dashboard’ and hyperflexion mechanisms result in isolated PCL injury with only mild or moderate laxity. Hyperextension injuries, especially when combined with varus, will result in more severe PCL and posterolateral damage. Careful clinical assessment should be complemented by plain X-rays to exclude bone avulsions. MRI scans should be considered in competitive athletes with more severe injuries. Athletes with isolated PCL injuries are ideally treated conservatively. Non-operative treatment may include initial joint aspiration if the patient has a painful tense haemarthrosis. Splintage in full extension is appropriate for patients who are unable to bear weight on the injured limb. Active quadriceps and range of motion exercises should be initiated as soon as comfort allows. Intensive quadriceps strengthening should be pursued according to patient symptoms. Return to sport is progressed on an individual basis. The role of braces for PCL injuries remains controversial. Following acute injury competitive athletes will return to sport by 4᎐8 weeks.

Magnetic resonance Good with acute injuries, ask for thin cuts, may over diagnose Grade III injuries. Specific pattern of bone bruises, viz. antero-medial femoral condyle with PCL Žposterolateral corner. injuries. Chronic lesions ᎏ not as sensitive, 40% chronic PCLs missed, normal cuts will also miss postero-lateral injury. Mechanical axis Mechanical axis in both AP and sagital planes may determine outcome. 䢇

䢇

䢇

Mechanical plan 䢇

䢇

Combined PCL and PLC ` Repair lateral structures ` Single tunnel PCL at same time, or as second stage procedure, depending on symptomslactivity levellage

䢇

Isolated PCL ` Grade I no treatment ` Grades II and III consider biplanar osteotomy if symptomatic

Until you make a full diagnosis you cannot begin to understand or treat these lesions.

Associated injuries ᎏ popliteal artery Obtain arteroigram if injury suspected in acute cases. Common peroneal nerve up to 16% involvement. Examination Do this walking, supine and prone. PCL

ᎏ

Postero LCL ACL MCL

ᎏ ᎏ ᎏ ᎏ

posterior sag Žlack of medial step off., posterior drawer lateral corner-dial test Žprone. at 30 and 90⬚ varus at 30⬚ Lachman. Pivot shift. valgus at 30⬚

Other useful tests 1. 2. 3. 4.

EUA Stress views ᎏ awake andror GA Plain X-ray ᎏ Puddu view MR scan

Isolated PCL ` Grades I᎐II conservative ` Grade III conservative Žsome would reconstruct .

Acute

r complex injuries — r PLRIr An algorithm for management of PCLr key points NP Thomas Basingstoke, UK

History of original injury May not be high velocity but most are. Must have a detailed knowledge of the anatomy of the region, viz. PCL, Iliotibial band, lateral capsule, LCL, popliteus including popliteo-fibular ligament, biceps femoris, lateral gastroenemius.

Lateral thrust ᎏ needs corrective tibial osteotomy Žopening is theoretically best. Increase in posterior tibial slope in sagital plane will decrease posterior translation. A biplanar osteotomy should be performed prior to reconstructive surgery and in some cases Žsee below. may be enough to control symptoms.

Chronic 䢇

Combined PCL and PLC ` Two tunnel PCL with posterolateral reconstruction ` Reconstruction of other laxities, viz. ACL, MCL "biplanar tibial osteotomy

References 1. Covey DC. Injuries of the posterolateral corner of the knee. J Bone Joint Surg Am 2001;83-AŽ1.:106᎐118. 2. Hayes CW, Brigido MK, Jamadar DA, Propeck T. Mechanism-based pattern approach to classification of complex injuries of the knee depicted at MR imaging. Radiographics 2000;20:S121᎐S134. 3. Strobel MJ, Weiler A, Eichhorn HJ. Diagnosis and therapy of fresh and chronic posterior cruciate ligament lesions. Chirug 2000;71Ž9.:1066᎐1081. 4. Stayner LR, Coen MJ. Historic perspectives of treatment algorithms in knee dislocation. Clin Sports Med 2000;19Ž3.: 399᎐413. 5. Harrier CD, Vogrin TM, Hoher J, Ma CB, Woo SL. Biomechanical analysis of a posterior cruciate ligament reconstruction. Deficiency of the posterolateral structures as a cause of graft failure. Am J Sports Med 2000;28Ž1.:32᎐39.

Abstracts 6. Wang CJ, Chen CY, Chen LM, Ych WL. Posterior cruciate ligament and coupled posterolateral instability of the knee. Arch Orthop Trauma Surg 2000;120Ž9.:525᎐528. 7. Lobenhoffer P. Chronic instability after posterior cruciate ligament injury. Tactics, techniques and results. Unfallchirug 1999;102Ž11.:824᎐838. 8. Shahane SA, Ibbotson C, Strachan R, Bickerstaff DR. The popliteofibular ligament. An anatomical study of the posterolateral corner of the knee. J Bone Joint Surg Br 1999;81Ž4.:489᎐494. 9. Bleday RM, Fanelli GC, Giannotti BF, Edson CJ, Barrett TA. Instrumented measurement of the posterolateral corner. Arthroscopy 1998;14Ž5.:489᎐494. 10. Ochi M, Adachi N, Sumen Y, Uchio Y, Iwasa JA. New guide system for posteromedial portal in arthroscopic knee surgery. Arch Orthop Trauma Surg 1998;118Ž1᎐2.:25᎐28. 11. Albright JP, Brown AW. Management of chronic posterolateral rotatory instability of the knee, surgical technique for the posterolateral corner sling procedure. Instr Course Lect 1998;47:369᎐378. 12. Miller TT, Gladden P, Staron RB, Henry JH, Feldman F. Posterolateral stabilizers of the knee: anatomy and injuries assessed with MR imaging. Am J Roentgenol 1997; 169Ž6.:1641᎐1647. 13. Ross G, Chapman AW, Newberg AR, Scheller AD. Magnetic resonance imaging for the evaluation of acute posterolateral complex injuries of the knee. Am J Sports Med 1997; 25Ž4.:444᎐448. 14. Noyes FR, Barber-Westin SD. Treatment of complex injuries involving the posterior cruciate and posterolateral ligaments of the knee. Am J Knee Surg 1996;9Ž4.:171. 15. Anderson DD. Effects of sectioning of the posterior cruciate ligament and the posterolateral complex on the articular contact pressures within the knee. J Bone Joint Surg Am 1995;77Ž4.:649. 16. Veltri DM, Warren RF. Operative treatment of posterolateral instability of the knee. Clin Sports Med 1994;13Ž3.:615᎐627. High tibial osteotomy is no longer indicated in the management of primary osteoarthritis of the knee C Dodd Oxford, UK High tibial osteotomy has long been used in the treatment of primary osteoarthritis of the knee, particularly in the younger patient group with high activity demands. Most studies indicate a 70᎐80% chance of pain relief with a 90% chance of 5-year survivorship, dropping to a 65% 10-year survivorship. There are numerous techniques of high tibial osteotomy surgery and increasingly, overcorrection is thought to be key in providing predictable results. HTO has a reputation as being unpredictable surgery fraught with a significant number of potential complications. In the last 4 years there has been a renewed interest in uni-compartmental arthroplasty as being a viable alternative to HTO in the management of this patient population. There is very little data directly comparing the relative merits of HTO vs. uni-compartmental arthroplasty in this patient population. There have been no randomised control trials, affording a direct comparison, so we have sought to address this problem by comparing match groups of patients representing what is considered to be the best possible outcome following uni-compartmental replacement and high tibial osteotomy surgery. Match groups of patients were selected from a published cohort of patients whose surgery was performed by one of the premier experts in HTO surgery These patients were sent the Oxford questionnaire Žscores 0᎐48. to assess patient satisfaction and the

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cohort of patients, whose average age was 55, scored 26 out of 48. A match group of patients undergoing Oxford Uni, average age 55, scored 38 out of 48. Clearly a substantial difference favouring the Uni in terms of function. In terms of survivorship, the HTOs had a 10-year survivorship of 65%, whereas the matched Uni cohort had a 10-year survivorship of 95%. Again, a substantial difference favouring the Uni. In summary, in terms both of function Žpatient satisfaction . and long-term survivorship, Uni-compartmental arthroplasty provides a much more predictable outcome in the management of primary osteoarthritis of the knee. Increasingly therefore, one can argue that HTO has no real place to play in the management of this patient group. High tibial osteotomy is an historical operation G MacEachern Torbay, UK I refer you to ‘High Tibial Osteotomy Using a Dynamic Axial External Fixator’ ŽAE Weale, MB, BS; AS Lee, MA; AG MacEachern, MB, BS. Clinical Orthopaedics Related Research, no. 382, pp. 154᎐167. High tibial osteotomy is an accepted treatment for uni-compartmental osteoarthritis of he knee. Conventional osteotomy can be a demanding procedure with potential for complications. Opening wedge, high tibial osteotomy using an external fixator is an alternative that may have advantages in comparison with classic methods. The aims of the current study were to determine if opening wedge osteotomy using hemicallotasis techniques is safer than, and the outcome comparable with that of, conventional techniques. Seventy-six high tibial osteotomies were performed in 65 patients for primary osteoarthritis. The mean age of the patients was 54.8 years Žrange, 36᎐70 years.. The mean follow up was 6 years. The only serious complication occurred in one patient, who had chronic osteomyelitis develop 2 years after surgery. There were no neurological or vascular complications. The authors think this technique is safer than conventional techniques. Survivorship at 5 and 10 years was 89 and 63%, respectively. The mean knee score in osteotomies was 26.6 Žmaximum possible score, 48.. The outcome is comparable with, or better than, that of other techniques for osteotomy. Subsequent knee replacement, in cases requiring conversion, was straightforward. The mean score in knees that had osteotomies that were converted to total knee replacement was 33.7. Thus, in summary, I submit that HTO is not an historical operation but agree that it is in fact, an historic operation. Long-term results of TKA after high tibial osteotomy T Wilton Derby, UK Introduction Many patients presenting with osteoarthritis of the knee, have damage to the knee which is, to a greater or lesser extent, confined to the medial compartment. Such patients represent a group in whom high tibial osteotomy ŽHTO. suitably performed in wellselected cases, may give reasonable functional results which can be very long-lasting w1x. The technique and patient selection may be critical, but if appropriate guidelines are used, excellent survivorship of the osteotomy has been demonstrated in their study. Other surgeons, however, have not demonstrated quite such satisfactory results from HTO and frequently the failure rate tails off gradually over a period of years, both from the point of view of

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Abstracts

revision and also from the point of view of less satisfactory pain relief. Surgeons have been naturally reluctant to pursue the more radical surgical alternative of total knee arthroplasty ŽTKA. in such patients for a variety of reasons: 1. These are often younger and more active patients 2. The inevitable toll of wear and tear on the TKA may lead to early revision in such patients 3. It has been perceived that HTO is ‘buying time’ for such patients, but that subsequent TKA will often be necessary, but is likely to be successful. A number of assumptions are clearly being made in such a decision and it is of considerable interest that the willingness of surgeons to perform HTO, and the current prevalence of that operation, appears to vary widely between North America and various parts of Europe, despite broadly similar populations of patients being operated upon. One reason why surgeons do such surgery is certainly that a successful HTO may allow continued activity at a level not recommended to TKA patients. A recent publication by Diduch and colleagues Ž1997. has, however, demonstrated outstanding results in patients undergoing TKA under the age of 55 years Žmean, 51 years.. These patients were followed for a mean of 8 years Žrange, 3᎐18 years. and showed survivorship of the knee replacement of 94% at 18 years Ž90% including patella failures .. Because of their younger age, these patients did in fact return to greater activity compared with most knee arthroplasty groups and significant numbers returned to activities giving them a Tegner activity rating of 5 or 6 points. This is comparable to non-operated patients of a similar age. Many papers over the last 12 years have addressed the issue of outcome of TKA after previous HTO ᎏ these have usually had relatively short follow-up, often have relatively small numbers involved and have given variable results. We studied our own cases selected from a TKA database, to give two comparable groups of TKA with long-term follow-up, so as to address the issues of failure and revision, as well as functional outcome. Material Our database contained 51 patients undergoing TKA between 1980 and 1992, who had undergone previous HTO, and were still alive and available for further review. More such patients had undergone operation, but were known to be deceased and follow-up had not been long-term at the time of their death. These patients were not therefore, included in the present study. The 51 patients were matched for age, gender, diagnosis, prosthetic design and fixation, and in particular for length of follow-up. They were also matched for operating surgeon. All of the patients in both groups were specifically reviewed for the purpose of this study, and data collected to allow full clinical assessment and to allow HSS scores and BOA ŽBritish Orthopaedic Association. clinical assessment to be undertaken. Radiological assessment was undertaken, including sagittal and coronal alignment, evidence of wear and loosening, and also assessment of patella height by the Insall᎐Salvati ratio. Failure was assessed according to clinical score and subjective criteria Žpatient assessment . as well as by the revision rate and re-operation rate. Results The two groups were well matched according to the criteria selected above and in particular, great care was taken to produce comparable lengths of follow-up by selecting control cases closely

by date of operation. Mean follow-up was 12.8 years Žrange, 6᎐19 years.. Knee alignment and coronal orientation of the components did not differ significantly between the two groups. There was no significant difference in mean HSS score between the two groups, the HTO group scoring 80 and the control group 81 at long-term follow-up. The similar mean HSS scores hide the fact that there were significantly more Ž9 vs. 2. cases with a poor result in the HTO group. A poor result was defined as an HSS score less than 60. This was at the expense of good rather than excellent results, such that a similar number in the two groups in fact still showed an excellent outcome at 12.8 years mean follow-up. The proportion of good and excellent results was only 80% in the HTO group, compared with 90% in the control group. The HTO patients had significantly decreased flexion Žmean s 93⬚. compared to the control group Žmean s 105⬚.. This was associated with a slightly increased tendency to produce an upward sloping tibial cut in the sagittal plane in the HTO group. There was no increased tendency to produce Patella Baja in the HTO group. Eleven cases were surgical failures in the HTO group and required further major surgery. Eight underwent revision TKA, two underwent arthrodesis and one an above knee amputation. In contrast, there were four revision TKAs in the control group, but no cases requiring amputation of arthrodesis. Almost all of the revision surgery took place 6 years or more after the index arthroplasty. This difference Ž11 vs. 4. is statistically significant. Ž Ps 0.05.. The incidence of any case of arthrodesis or amputation is clearly of considerable clinical concern. The mean interval between HTO and subsequent arthroplasty was 6 years, but varied considerably ᎏ range, 6 months to 17 years. The serious nature of the complications of arthrodesis and amputation deserves specific attention. The amputation was performed 16 years after the original operation. The TKA had failed mechanically and attempts had been made to arthrodese the knee. These attempts failed and a subsequent intramedullary nail fractured, culminating in ongoing pain and leading to eventual amputation of the leg. One of the arthrodeses certainly occurred following specific complications attributable to the previous HTO. This was a patient who underwent TKA and developed an acute swelling of the knee and leg in the early post-operative period. A false aneurysm of the posterior tibial artery was demonstrated by arteriogram. Exploration and ligation of the aneurysm was performed, but the TKA then became infected. At that time it was felt best to arthrodese the knee rather than to risk major further complications. The false aneurysm occurred precisely at the level of the tibial resection, and was presumably caused by adherence and scarring around the artery at the level of the previous HTO. This is a complication, which in our experience has been unique in over 5000 condylar TKAs. The other arthrodesis occurred due to late infection some 8 years after the original HTO and an obvious connection to the fact of previous HTO was difficult to establish. Discussion HTO is a well-established surgical procedure with clear indications in certain groups with unicompartmental degenerative knee arthritis. It is arguable that unicompartmental knee arthroplasty ŽUKA. may be more appropriate in these cases but the indications are not identical and, in many cases, the reasons for reluctance to perform TKA apply also to UKA.

Abstracts If HTO is to be supported, then clearly it is important that certain conditions must ideally be met. 1. The result of HTO in terms of restoration of function and pain relief, should be comparable to, or better than, TKA. 2. The HTO should last a substantial period of time. 3. Once it fails, a previous HTO should not adversely affect the outcome of the TKA. 4. The results of TKA should not deteriorate more rapidly following HTO than following TKA. Odenbring et al. w1x have demonstrated excellent survivorship of HTO in suitably selected cases, provided adequate correction was obtained. Their own figures, however, suggest that in those cases which were left under-corrected, the revision rate approached two out of three cases at 13 years. Furthermore, Insall et al. w3x suggest that only 35% of HTOs retain good pain relief after 9 years. In contrast to the findings of Odenbring et al. w1x our own patients had gained a reprieve of only 6 years Žmean. by undergoing HTO and in some cases little or no relief was obtained and TKA was, in effect, precipitated by the HTO. This is in keeping with the results of Gill et al. w4x, Windsor et al. w5x, and Staeheli et al. w6x, all of whom have noted an average of 6 years relief following HTO in those cases undergoing subsequent TKA. Clearly, the early failures may be exceptions and may have been caused by inadequate correction or otherwise unsatisfactory technique at the time of HTO. Nevertheless, the possibility of complications is a ‘clear and present danger’ at the time of HTO and our results suggest that such complications, as well as sometimes precipitating the need for TKA, may also subsequently render the TKA less durable and less clinically satisfactory. Previous studies by Windsor et al. w5x, Katz et al. w7x, Nizard et al. w8x and Mont et al. w9x, have all suggested less satisfactory outcome from TKA following HTO than is to be expected from primary TKA. Other authors have failed to demonstrate any such association and have found similar results of TKA after HTO or primary TKA ŽBergenudd et al. w10x and Staeheli et al. w6x.. All of these studies have followed the patients for relatively short periods after TKA Žusually mean follow-up of 2᎐5 years. and in some, the small numbers of patients in the HTO group Žbeing only approx. 20 cases. would not be sufficient to demonstrate differences unless they were very substantial. This study, with over 50 cases followed-up in each group for a substantial period Žmean, 12.8 years., showed that most of the failures were occurring 6 years or more after the TKA, which strongly suggests that previous studies with shorter follow-up should be interpreted with caution. Our patients demonstrated significantly less good flexion after HTO than in the control group, a finding in keeping with those of Amendola et al. w11x and Nizard et al. w8x.

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Conclusion These findings demonstrate less satisfactory results from TKA after previous HTO and the HTO cannot therefore, be regarded as a ‘cost-free option’. The mean ‘time bought’ by the HTO was 6 years, but some 18 months of this was generally spent on a waiting list awaiting re-operation to TKA. The TKA is likely to flex somewhat less satisfactory after prior HTO, and pain persists more frequently and is more severe. This is not a randomised controlled trial, nor are the differences between the two groups dramatic. Some differences are, however, significant, and the use of tibial osteotomy as a prelude to subsequent TKA should therefore be undertaken with caution, and only in those ideally suited to tibial osteotomy. This is particularly the case in light of the excellent results shown by Insall et al. w3x, even in younger patients undergoing TKA. References

1. Odenbring S, Egund N, Knutson K, Lindstrand A, Toksvig Larsen S. Revision after osteotomy for gonarthrosis. Acta Orthop Scand 1990;61Ž2.:128᎐130. 2. Diduch DR, Insall JN, Scott WN, Scuderi GR, Font-Rodriguez D. TKR in young active patients. Long-term follow-up and functional outcome. JBJS 1997;79A:575᎐582. 3. Insall JN, Joseph DM, Msika C. HTO for varus gonarthrosis. A long-term follow-up study. JBJS 1984;66A:1040᎐1048. 4. Gill T, Schemitsch EH, Brick GW, Thornhill TS. Revision total knee arthroplasty after failed UKA or HTO. CORR 1995;321:10᎐18. 5. Windsor RE, Insall JN, Vince KG. Technical considerations of TKA after HTO. JBJS 1988;70A:547᎐554. 6. Staeheli JW, Cass JR, Morrey BF. Condylar total knee arthroplasty after failed HTO. JBJS 1987;69A:28᎐31. 7. Katz MM, Hungerford DS, Krackow KA, Lennox DW. Results of TKA after failed HTO for osteoarthritis. JBJS 1987;69A:225᎐233. 8. Nizard RS, Cardinne L, Bizot P, Witvoet J. TKA after failed HTO. J Arthroplasty 1998;13:847᎐853. 9. Mont MA, Antonaides S, Krackow KA, Hungerford DS. TKA after failed HTO. CORR 1994;299:125᎐130. 10. Bergenudd H, Sahlstrom A, Sanzen L. TKA after failed HTO. J Arthroplasty 1997;12:635᎐638. 11. Amendola A, Rorabeck C, Bourne RB, Apyan PM. TKA following HTO for OA. J Arthroplasty 1989;4ŽSuppl..:S11᎐S17.