- Email: [email protected]
The natural history of anterior cruciate ligament reconstruction using patellar tendon autograft
UTTERWORTH EINEMANN
Copyright
The Knee Vol. 2. No. 4, pp. 211-217, 1995 Q 1996 Elsewer Science Ltd. All rights reserved Printed in Great Britain 096WX60195 $10.00 + 0.00
PIJ: s0968-0160(96)00009-9
The natural history of anterior ligament reconstruction using tendon autograft T D Zavras’, ‘Imperial
College
R P Mackenney2, London;
‘Watford
cruciate patellar
A A Amis’ General
Hospital,
Watford,
UK
Summary The purpose of this study was to review the results of ACL reconstruction using a patellar tendon graft placed ‘over the top’ plus a Macintosh lateral tenodesis, examining changes in knee laxity and functional status with increasing time. There were 74 patients operated on over an 11 year period, and divided into four groups for analysis according to postoperative time. There was a significant and progressive increase in side-to-side laxity difference with time, although functional status did not change significantly, indicating a lack of correlation between objective clinical tests and subjective findings. The highest Lysholm, Tegner and IKDC scores were at 4-5 years after operation, when 60% of patients were at their pre-injury level of sports activity. However, there was always a very significant difference between actual and desired Tegner activity levels for the group as a whole. While there was a significant correlation between degenerative changes and the time between injury and reconstruction, there was no correlation with postoperative time: this provides evidence that ACL reconstruction can protect the knee from later degeneration. Copyright 0 1996 Elsevier Science Ltd. Key words:
Anterior
cruciate ligament,
The Knee Vol. 2, No. 4,
211-217,
knee, patellar ten’don reconstruction
1995
Introduction The anterior cruciate ligament (ACL) is the primary restraint against anterior tibia1 displacement’ and its reconstruction is essential to restore normal knee joint laxity. A range of reconstruction methods have been devised, using autogenous, allograft and synthetic graft materials, and research continues in an effort to optimize the procedure: an appropriate graft must be positioned and tensioned so as to reliably reproduce the characteristics of the normal ACL. Recently, the patellar tendon graft has been most popular”,3, in view of its biomechanical suitability, with adequate tensile strength4 and its role as a scaffold that allows for proliferation of a new ligamentous structure’. Clinical studies of the use of this graft with more .than 4 years follow up &” have found subjective successrates between 69% and 98%, with the Lachman sign
Accepted: April 1996 Correspondence and reprint requests to: Dr A.A. Amis, PHI), CENG, FIMECHF, Reader in Orthopaedic Biomechanics, Department of Mechanical Engineering, Imperial College of Science, Technology and Medicine, London SW7 ZBX, UK
negative in 14% to 90%, and the pivot shift sign negative in 43% to 98%. Although the results of an extra-articular tenodesis alone have been less reliable” and an extra-articular graft does not add anything to a knee with an intraarticular reconstruction following isolated ACL damage13, these procedures often find a role in reconstruction of chronic ACL deficiency in which other structures have stretched, when they are used in conjunction with an intra-articular procedure14, as in this study. The purpose of this paper is to demonstrate the natural history of the bone-patellar tendon-bone reconstruction of the ACL, with patients reviewed up to 11 years after operation, describing the status of the joint at a range of postoperative times. A particular aim was to obtain objective data on long-term anterior tibiofemoral laxity changes. Apart from the study of Sandberg and Balkfors”, who found no laxity change between 2 and 5 years post-operation, we are not aware of objective laxity data having been published previously for different follow-up times, despite concern that ACL reconstructions may stretch with time, leading to an insidious return of abnormal anterior-posterior
212
The Knee Vol. 2, No. 4, 1995
(A-P) knee laxity. A further objective was to examine the hypothesis that ACL reconstruction can protect the knee from osteoarthrosic changes: although it is wellknown that many chronic ACL-deficient knees suffer degeneration”~i6, there is little evidence to show that ACL reconstruction can prevent this, despite it being a major long-term aim of the surgery. Patients and methods We fully evaluated 74 patients (53 men and 21 women) who were operated on by a single surgeon (R.P.M.) using a standard operative technique between 1983 and 1993. The patients were an average age of 25 years at the time of surgery, with chronically ACL-deficient knees. The patients were evaluated as a whole (mean follow-up 4.1 years), and then divided into four groups according to their follow-up period (Table 1). The original injuries were the result of contact in 26 and a non-contract mechanism in 48 (Table 2). Football (soccer) was the sport most commonly related to the injury (Table 3). The indication for reconstruction was recurrent subjective instability, sometimes in everyday activities and in others only when they participated in a particular sport, which had failed to respond to physiotherapy. The pivot shift sign and the Lachman test were positive in all knees. Damage to the ACL was confirmed arthroscopically before further surgery. At that time procedures other than the ACL reconstruction were performed (Table 4). The operations were at an average time of 30 (range 2-84) months after the injury, using the technique described by Paterson and Trickey17, with the medial one-third of the patellar tendon used as an intraarticular graft. It was fixed ‘over the top’ under tension
Table
Group
1.
Study
(nl
A (12)
groups Mean follow up and range (years and months)
Age (years)
0.9 years ( 7-14 months) 2.3 (18-36) 4.5 (41-70) 8.5 (78-l 29)
B (28) c (20) D (14) Total:
74 Mean:
4.1
Table
2. Mechanism
26 27 30 32 Mean:
29
of injury
Contact Tackle from the back Direct blow or tackle at the lateral side Road traffic accident
26 5
Non-contact Twisting Hyperextension
48 43 5
18 3
Table
3. Sports-related
initial
injury
Football (soccer) Rugby football Netball Skiing Basketball Hockey Martial arts Running Squash Tennis Climbing
37 6 5 5 4 3 2 2 2 1 1
Total
68
Table
4. Other
surgical
procedures
related
to the initial
injury Procedure Medial Lateral
n meniscectomy meniscectomy
Total
23 (8 bucket 5 (2 bucket
handle) handle)
28
with the knee at 30” of flexion. This was supplemented by an extra-articular tenodesis as described by Galway, Beaupre and Macintosh”, and Ireland and Trickeyi’. All patients underwent the same postoperative rehabilitation programme. The leg remained in plaster at 15” knee flexion for 4 weeks, non-weight bearing, after which the patient was readmitted for treatment on a passive mobilization machine until 70” flexion had been achieved. Full weight bearing was permitted at 6 weeks and outpatient physiotherapy was continued with the use of a Cybex II isokinetic exercise machine for 3-8 months depending on patient requirements. Non-contact sport was allowed as soon as satisfactory muscle bulk was obtained, and contact sports were permitted 1 year after the repair. All 74 patients were reviewed clinically by T.D.Z., who had not been involved in their previous care or management. Assessmentmethods The patients were evaluated using a questionnaire including Lysholm and Tegner activity scores, physical examination, one-legged single hop test, KT-2000 arthrometry, lateral stressradiography measurements, and A-P tunnel-view weight-bearing radiographs. All tests were performed with the patient conscious. The range of flexion-extension was measured with a goniometer and compared with the uninjured knee. The anterior drawer, posterior sag, collateral stability, Lachman and pivot-shift tests, were also compared to the uninjured knee. These were graded as follows, compared to the uninjured knee: 0, the same; +l, O-5 mm extra movement; +2, 5-10 mm; +3, 10-15 mm; +4, >15 mm, apart from the pivot shift, which was graded as either present or absent”.
Zavras
The overall evaluation and the grading of the radiographs were based on the International Knee Documentation Committee (IKDC) Standard Ligament Evaluation Form”.
et al.: ACL reconstruction
with patellar
tendon
213
graft
test. The relationship between instrumented and radiographic laxity differences was examined using Spearman’s rank correlation coefficient. The correlation of lack of extension with overconstraint of the joint or a low Lysholm score was determined by the x2 test.
KT 2000 arthrometer Measurements were taken for both knees with the joint flexed between 20” and 30”. Starting with the leg in neutral rotation and the tibia resting posteriorly, a ‘manual maximum’ anterior drawer force was applied to the KT arthrometer, giving an anterior laxity reading in millimetres’“. This was repeated five times for both knees and a mean laxity difference calculated. Stress radiographs Lateral stress views of each knee were obtained with the patient supine and the knee flexed 20”. The calf was supported while a 5 kg sandbag plus the weight of the thigh caused the femur to fall posteriorly, stressing the ACL. The cassette was placed medially, with the X-ray tube 120 cm from the knee, and angled 5-8” distally23. Statistical analysis
Group A 8 c D
6. Subjective,
In)
(12)
(28) PO) (14)
Total:
74
means:
Ten patients were operated on again after the ACL reconstruction (Table 5). The KT-2000 and stressradiography methods of instability evaluation were correlated significantly (P < 0.01). However, we noticed that we had more than 2 mm difference between the methods in 11 cases.In 12 cases,including these 11, the lateral radiographs were considered unacceptable, since the distance between the posterior outlines of the condyles in the sagittal plane was more than 6 mm. We therefore based our analysis on the KT stability data. For the group as a whole, 91% had a negative pivot shift test, 58% had a side-to-side anterior laxity difference ~2 mm, and 88% had subjectively satisfactory results, with a Lysholm score greater than 76. Overall, acording to the IKDC evaluation, 77% had successful results. The results for the groups at different times are shown in Tables 6 and 7.
Linear regression analysis was used to evaluate the changes over time, and to examine the effect of the time interval between injury and operation, and between operation and review, on arthritic degenerative changes indicated by joint space narrowing. To test differences between groups we used the x2 test for the IKDC score and the pivot shift sign, and the unpaired t-test for the single hop. Differences in Tegner’s activity score before and after operation, and the differences of the Tegner and Lysholm scores between the postoperative groups were evaluated with the Wilcoxon
Table
Results
results
5. Surgical reconstruction
MUA Patella shaving Meniscectomies Removal of fixation
2 2 2 4
(imean values,
10
and overall
Follow up (years)
L ysholm score
Tejgner score
Single hop l% normal)
0.9 2.3 4.5 8.5
86.6 89.0 91.6 91.5
6 6.8 7 6.8
78.5 90.25 94.8 91
4.1
89.6
6.7
88.6
0.9 2.3 4.5 8.5 Mean:
4.1
Tegner
staple
Total
objective,
Lysholm
ACL
n
number
7. Follow up, % Lysholm scores 377, Tegner scores 36, % negative negative pivot shift signs, % IKDC scores ~2 (excellent and good results) up (years)
following
Procedure
Table
Follow
procedures
Table
Lachman
of positive
pivot signs)
Lachman (mm difference by KT-2000)
Pivot sign
IKDC score
0.33 0.82 2.81 4.41
0 2 2 2
2.33 2.28 1.95 2.25
2.09
6
2.2
Lachman
test (~2 mm side difference),
Pivot
IKDC
89 82 91 91
56 83 87 75
89 75 50 9
100 93 91 84
67 75 87 75
88
75
58
91
77
%
214
The
Knee
Vol. 2, No. 4, 1995
Table 6)) and there was no deterioration of performance between 2.3 and 8.5 years after operation. Range of knee motion
5 g 2 g s
Overall, 32 patients lacked full extension and 30 patients lacked full flexion. In group A the mean losses were 5” extension and 16” degrees flexion, while groups B, C and D lost a mean of 4” extension and 9” flexion. There was no significant relationship between lack of extension and either low Lysholm scores or overconstraint (P > 0.05).
35 30 25 20 15 IO 5 0
Figure 1. Side-to-side groups at different times 20” knee flexion.
Subjective evaluation Lysholm score The mean Lysholm score did not change significantly with time (P = 0.1, Table 6). anterior laxity after operation,
differences using KT2000
in at
Objective evaluation A-P Laxity The A-P laxity increased significantly as a function of postoperative time (P < 0.001; Table 6 and Figure 1). The side-to-side difference had a range from -3 mm to 8 mm, and increased by 4.1 mm between the groups at 0.9 and 8.4 years mean follow up (Table 6). In the first two groups, up to 3 years after operation, there were 16 overconstrained knee joints (35%), while there were none after this time. We did not find a significant correlation between overconstraint and either low Lysholm scores or loss of extension (0.1 > P > 0.05).
Tegner score The Tegner activity level score did not change significantly with time (P = 0.07), and never reached the preinjury or desired levels for each group of patients (P < 0.001, Table 8). Removing the patients with positive pivot and giving way did not change the significance of the difference between the preinjury and postoperative activity levels (P < 0.001). Overall, 47% of the individual patients, and 60% of those in group C (at 4.5 years mean follow up) had returned to the same Tegner activity level as before injury. Pivot shift test Six patients had a positive pivot shift test, two in each of the longer term follow-up groups, and there was no significant increase with time (P > 0.1). None of them had a gross subluxation and two doubtful cases were considered as positive.
Radiographic findings
Giving way
We classified the radiographic findings according to the IKDC2’. There was no significant change between the preoperative and follow-up radiographs, and hence no significant development of degenerative changes over the follow up time (P > 0.5). However, joint space narrowing and patellofemoral joint arthritic deterioration were correlated with the time between injury and operation (P = 0.02). The mean number of osteophytes at follow up was 1.9 (range O-7), and there was no significant correlation either with the interval between injury and operation, or between operation and last follow up (P > 0.05). In all cases but two the osteophytes appeared smaller than 5 mm.
Eight patients complained of giving way, with a frequency ranging from rarely during athletic activities to occasionally during daily activities. One was from the first group, three from the second, three from the
Table
8. The Tegner
activity Tegner
Group
A B
score activity
score
Before injury
After injury
Post-op
Desired
6 6.7 7 6.8
8.3 7.6 7.9 7.6
6.7
7.8
Single hop test
C
8.2 7.7 8
D
7.9
2.7 3.3 3.1 ,3.4
There was a significant difference between the first group of patients and the other groups (P = 0.03,
Total
8
3.2
Zavras
third, and one from the fourth; we elicited a positive pivot shift in four of them. Overall evaluation IKDC score The mean values and the percentage of excellent and good IKDC scores, are shown in Tables 6 and 7; there was no deterioration of the score with time (P = 0.12).
Discussion There has been very little work which has attempted to show how objective measurement of excessknee laxity varies with time, or how this laxity correlates with changes in knee function as the postoperative time increases. Sandberg and Balkfors” found no change in objective anterior knee laxity or return of a positive pivot-shift between 2 and 5 years post-operation, although the subjective Lachman test was positive in 87% at 5 years. Our study has the drawback of being a retrospective review, rather than a study of one set of patients studied prospectively for 11 years, but the patients were all operated-on by a single surgeon who did not change any detail of the procedure throughout. Although this study found a significant increase in ibP laxity with postoperative time, this progressive change did not correlate with function as assessedby the pivot shift and the patient’s activity level. The first 3 years of this reconstruction were characterized by the existence of overconstraint of .&P laxity, which disappeared afterwards. This overconstraint did not influence the perceptions of the patients (no correlation with knee pain, for example), nor did it reduce the range of joint motion significantly. Although it has been shown that overtightening of an ACL graft can cause malarticulation and increased forceszs, we did not observe significant radiographic changes after operation. In the group of patients followed-up for a mean of 4.5 years (range 41-70 months), the overconstrained joints had disappeared and the group as a whole was now becoming slacker than normal: our data suggest that the grafts stretched progressively with time. With a mean Lachman laxity difference of 2.8 mm most of our patients were still ‘almost normal’ according to the IKDC2’, and this was the time when the functional scores (Lysholm, Tegner and IKDC) were best (Table 6). Although this was the time when the largest proportion of patients (60%) were functioning at ‘their pre-injury activity levels, there was still a highlysignificant difference (P < 0.001) between the actual activity level of the group and that which was desire:dby them. In the group of patients at a mean of 8.4 years since the operation the graft had stretched further, and the joints presented a mean side-to-side laxity difference of 4.4 mm. Thus the laxity had increased by a rnean 4.1 mm over the 7.5 years between groups A anld D.
et al.: ACL reconstruction
with patellar
tendon
graft
215
Although there is no fixed relationship between laxity and ACL length, due to the inclination of the ACL, the laxity change represents approximately 10% graft elongation. However, the function of the knee joint still remained nearly normal, with. the patients having maintained the level of activity to a mean Tegner score of 6.8. The fact that only 14% of group D had a positive pivot shift means that 4.4 mm excess laxity in the sagittal plane (the mean for this group) is probably not enough to cause a pivot shift in the presence of a lateral extra-articular reconstruction. A number of authors have noted that there can be a discrepancy between the objective measurements commonly performed in the postoperative evaluation of ACL reconstructions and what the patient perceives of the knee’s function7,‘2*25.26. Both this and other studies”s,‘o,12,‘4 have found a greater discrepancy between subjective and objective estimation for the Lachman sign than for the pivot shift, which is, therefore, often taken to be the clinical sign that is most closely related to symptomatic instability. This suggests that functional stability depends on control of subluxation with a rotary component, rather than just straight anterior laxity. The question of whether an extra-articular reconstruction should be added to an intra-articular ACL reconstruction is a matter for debate. Although there are many studies of patients with one or other of these approaches, there are few studies where the different strategies have been compared. Overall, there is no consensusin the literature in favour of adding an extraarticular reconstruction: while Noyes and Barberz7 found that it gave significantly better results, Jensen et a1.28and Strum et al. 29 found no significant difference, Roth et aZ.30 found greater laxity with a combined reconstruction(i.e. adding the extra-articular procedure had compromised stability) and, while O’Brien et al.3’ found no significant difference in function, they did find a 40% occurrence of symptoms related to the lateral procedure. Amis and Scammell’3, in a biomechanical study, found that the additional procedure did not give a closer approach to normality than an intra-articular graft alone in knees with an isolated ACL lesion, but suggested that this conclusion might change in the event of stretching of the secondary restraints, that might give greater rotary instability, when the pivot-shift would be more prominent. The evidence of this review, in which the pivot-shift remained absent in 85% at 8.5 years follow up despite significant stretching of the intra-articular graft, suggests that there is a place for lateral extra-articular procedures in addition to the intra-articular repair for controlling anterolateral rotatory instability of the knee. The intra-articular graft was placed ‘over the top’ (OTT) of the lateral femoral condyle in this series, a method which is technically simpler than use of a transcondylar drill hole. Despite this, the OTT route has become less popular following the promotion of isometricity and intraosseous fixation. Comparing the tunnel and OTT procedures Jonsson et aZ? found the
216
The Knee Vol. 2, No. 4, 1995
OTT superior on subjective assessment,and found no difference on objective examination. Conversely, Kornblatt et ~1.~ found the tunnel method gave 69% with no pivot, versus 47% when operated by the OTT method. In an experiment on canine joints using a bovine tendon xenograft3’, the OTT method was clearly superior regarding the incidence of rupture: 17% versus 91% for the tunnel method. The literature, therefore, does not provide a case for either method being superior, and we are not aware of evidence that an OTT graft will stretch more than one placed around an isometric point. It is noteworthy that both intraarticular OTT reconstructions and extra-articular reconstructions that pass deep to the lateral collateral ligament tighten as the knee extends’3,24, controlling tibia1 subluxation best when the knee is in a functional stance posture. When the graft was positioned, the patellar fragment was always placed against the raw surface of the femur following periosteal elevation. This ensured bone-bone fixation at both ends of the graft, and means that the laxity increases must have derived from graft elongation. The data show that degenerative changes were highly correlated (P = 0.02) with the time between injury and operation, and this is supported by other studies in which up to 45% of knees with an untreated ACL became arthrosic in the long term”~“. We did not observe a trend of development of arthritic changes with postoperative time this is evidence that ACL reconstruction can provide protection against joint degeneration, and is a significant finding in relation to the long-term objectives of ACL surgery. In view of the detailed findings described above, it may be hypothesized that this protection derives from avoidance of giving-way, that might cause meniscal lesions, rather than maintenance of normal anterior laxity.
Amiel D., Kleiner JB, Roux RD. The phenomenon ‘ligamentization’. 6
Howe JG, Johnson RJ, Kaplan MJ, Fleming B, Jarvinen M. Anterior cruciate ligament reconstruction using quadriceps patellar tendon graft. Part 1. Longterm followup. Am J Sports Med 1991; 19: 447-457
7
JohnsonRJ, ErikssonE, HaggmarkT, Pope MH. Fiveto-ten year followup evaluation after reconstruction of the anterior cruciate ligament. Clin Orthop 1984; 183:
8
Kornblatt I, Warren RF, Wickiewicz TL. Long term
122-134 followup of anterior using the quadriceps 9
10 11
12
13
14
1.5
17 18 19
1 2 3 4
Butler DL, Noyes FR, Grood ES. Ligamentous restraints to anterior-posterior drawer in the human knee. J Bone Joint Surg [Am] 1980; 62A: 259-270 Arnoczky SP, Warren RF, Ashlock MA. Replacement of the anterior cruciate ligament using a patellar tendon allograft. J Bone Joint Surg /Am] 1986; 68A: 376-385 Amiel D, Kleiner JB, Akeson WH. The natural history of the anterior cruciate ligament autograft of patellar tendon origin. Am J Sports Med 1986; 14: 449-462 Noyes FR, Butler DL, Paulos LE. Grood ES. Intraarticular cruciate reconstruction. 1: Perspectives on graft strength, vascularization and immediate motion after replacement. Clin Orthop 1983; 172: 71-77
cruciate ligament reconstruction tendon substitution for chronic
anterior cruciate ligament insufficiency. Am J Sports Med 1988; 16: 444-448
16
References
of
cruciate ligament
reconstruction with autogenouspatellar tendon. J Orthop Res 1986; 4: 162-172
Acknowledgements We thank Mr Paul Aichroth and the Wellington Hospital knee surgery unit for the use of the KT arthrometer. We also thank Mrs E.J. Snell from the Imperial College Mathematics Department for her statistics advice.
Anterior
20
21
22
Rackemann S, Robinson A, Dandy DJ. Reconstruction of the anterior cruciate ligament with an intra-articular tendon graft and an extra-articular tenodesis. J Bone Joint Surg (BrJ, 1991;73B: 368-373 Sandberg R, Balkfors B. The durability of anterior cruciate ligament reconstruction with the patellar tendon. Am J Sports Med 1988; 16: 341-343 Shelbourne KD, Whitaker HJ, McCarroll JR, Rettig AC, Hirrshman LD. Anterior cruciate ligament injury: Evaluation of intraarticular reconstruction of acute tears without repair. Am J Sports Med 1990; 18: 484-489 Bray RC, Flanagan JP, Dandy DJ. Reconstruction for chronic anterior cruciate instability. A comparison of two methods after six years. J Bone Joint Surg [Br] 1988; 70B: loo-105 Amis AA, Scammell BE. Biomechanics of intraarticular and extra-articular reconstruction of the anterior cruciate ligament. J BoneJoint Surg [Br] 1993; 70B: 812-817 Dandy DJ, Gray AJR. Anterior cruciate ligament reconstruction with the Leeds-Keio prosthesis plus extra-articular tenodesis. Results after six years. J Bone Joint Surg [Br] 1994; 76B: 193-6 Noyes FR, Mooar PA, Matthews DS, Butler DL. The symptomatic anterior cruciate deficient knee. J Bone Joint Surg [Am] 1983; 65A: 154-162 Jacobsen K. Osteoarthrosis following insuffiency of the cruciate ligament in man. Acta Orthop Stand 1977; 48: 52c-526 Paterson FWN, Trickey EL. Anterior cruciate ligament reconstruction using part of the patellar tendon as a free graft. J Bone Joint Surg [Br] 1986; 68B: 453457 Galway RD, Beaupre A, Macintosh DL. Pivot-shift: a clinical sign of symptomatic anterior cruciate insufficiency. J Bone Joint Surg [Br] 1972;54B: 763 Ireland J, Trickey EL. Macintosh tenodesis for anterolateral instability of the knee. J Bone Joint Surg [Br] 1980; 62B: 34c345 Elmquist LG, Lorentzon R, Langstrom M, Fugl-Meyer AR. Reconstruction of the anterior cruciate ligament. Long-term effects of different knee angles at primary immobilization and different modes of early training. Am J Sports Med 1988; 16: 455460 Hefti F, Drobny T, Hackenbruch W. et al. Evaluation of knee ligament injuries: The OAK and IKDC forms. In: Jakob RP, Staubli HU, eds. The Knee and the Cruciate Ligaments.Berlin: Springer-Verlag, 1990: 134-139 Daniel DM, Stone ML. KT-1000 Anterior-posterior displacement measurements. In: Daniel D Akeson W, O’Connor J, eds. Knee ligaments.Structure, Function, Injury, and Repair. New York. Raven Press, 1990: 427-447.
Zavras
23
24
25
26
27
28
Staubli H-U, Jakob RP. Our current technique of stressradiography near extension. In: Jakob RP, Staubli HU, eds. The Knee and the Cruciate Ligaments. Berlin: Springer-Verlag, 1990: 177-183 Amis AA. Anterior cruciate ligament replacement knee stability and the effects of implants. J Bone .Joint Surg [Br] 1989; 71B: 819-824 Anderson C, Odensten M, Good L, Gillquist J. Surgical or non-surgical treatment of acute rupture of the anterior cruciate ligament. J Bone Joint Surg [Am] 1989; 71A: 965-974 Jonsson H, Elmqvist LG, Karrholm J, Tegner Y. Overthe-top or tunnel reconstruction of the anterior cruciate ligament? J Bone Joint Surg [Br] 1994; 76B: 82X7 Noyes FR, Barber SD. The effect of an extra-articular procedure on allograft reconstructions for chronic ruptures of the anterior cruciate ligament. J Bone Joint Surg [Am] 1991; 73A: 882-892 Jensen JE, Slocum DB, Larson RL, James SL, Singer KM. Reconstruction procedures for anterior cruciate
et al.:
29
30
ACL
reconstruction
with
patellar
tendon
graft
217
ligament insufficiency: A computer analysis of clinical results. Am J Sports Med 1983; 11: 240-248 Strum GM, Fox JM, Ferkel RD et al. Intraarticular versus intraarticular and extraarticular reconstruction for chronic anterior cruciate ligament instability. Clin Orthop 1989; 245: 188-198 Roth JH, Kennedy JC, Lockstadt H, McCallum CL, Cunning LA. Intra-articular reconstruction of the anterior cruciate ligament with and without extraarticular supplementation by transfer of the biceps femoris tendon. J Bone Joint Surg [Am] 1987; 69A: 275-278
31
32
O’Brien SJ, Warren RF, Wickiewicz TL et al. The iliotibial band lateral sling procedure and its effect on the results of anterior cruciate ligament reconstruction. Am J Sports Med 1991; 19: 21-25 Montgomery RD, Milton JL, Terry GC, McLeod WD, Madsen N. Comparison of over-the-top and tunnel techniques for anterior cruciate ligament replacement. Clin Orthop 1988; 231: 144-153
Copyright
The Knee Vol. 2. No. 4, pp. 211-217, 1995 Q 1996 Elsewer Science Ltd. All rights reserved Printed in Great Britain 096WX60195 $10.00 + 0.00
PIJ: s0968-0160(96)00009-9
The natural history of anterior ligament reconstruction using tendon autograft T D Zavras’, ‘Imperial
College
R P Mackenney2, London;
‘Watford
cruciate patellar
A A Amis’ General
Hospital,
Watford,
UK
Summary The purpose of this study was to review the results of ACL reconstruction using a patellar tendon graft placed ‘over the top’ plus a Macintosh lateral tenodesis, examining changes in knee laxity and functional status with increasing time. There were 74 patients operated on over an 11 year period, and divided into four groups for analysis according to postoperative time. There was a significant and progressive increase in side-to-side laxity difference with time, although functional status did not change significantly, indicating a lack of correlation between objective clinical tests and subjective findings. The highest Lysholm, Tegner and IKDC scores were at 4-5 years after operation, when 60% of patients were at their pre-injury level of sports activity. However, there was always a very significant difference between actual and desired Tegner activity levels for the group as a whole. While there was a significant correlation between degenerative changes and the time between injury and reconstruction, there was no correlation with postoperative time: this provides evidence that ACL reconstruction can protect the knee from later degeneration. Copyright 0 1996 Elsevier Science Ltd. Key words:
Anterior
cruciate ligament,
The Knee Vol. 2, No. 4,
211-217,
knee, patellar ten’don reconstruction
1995
Introduction The anterior cruciate ligament (ACL) is the primary restraint against anterior tibia1 displacement’ and its reconstruction is essential to restore normal knee joint laxity. A range of reconstruction methods have been devised, using autogenous, allograft and synthetic graft materials, and research continues in an effort to optimize the procedure: an appropriate graft must be positioned and tensioned so as to reliably reproduce the characteristics of the normal ACL. Recently, the patellar tendon graft has been most popular”,3, in view of its biomechanical suitability, with adequate tensile strength4 and its role as a scaffold that allows for proliferation of a new ligamentous structure’. Clinical studies of the use of this graft with more .than 4 years follow up &” have found subjective successrates between 69% and 98%, with the Lachman sign
Accepted: April 1996 Correspondence and reprint requests to: Dr A.A. Amis, PHI), CENG, FIMECHF, Reader in Orthopaedic Biomechanics, Department of Mechanical Engineering, Imperial College of Science, Technology and Medicine, London SW7 ZBX, UK
negative in 14% to 90%, and the pivot shift sign negative in 43% to 98%. Although the results of an extra-articular tenodesis alone have been less reliable” and an extra-articular graft does not add anything to a knee with an intraarticular reconstruction following isolated ACL damage13, these procedures often find a role in reconstruction of chronic ACL deficiency in which other structures have stretched, when they are used in conjunction with an intra-articular procedure14, as in this study. The purpose of this paper is to demonstrate the natural history of the bone-patellar tendon-bone reconstruction of the ACL, with patients reviewed up to 11 years after operation, describing the status of the joint at a range of postoperative times. A particular aim was to obtain objective data on long-term anterior tibiofemoral laxity changes. Apart from the study of Sandberg and Balkfors”, who found no laxity change between 2 and 5 years post-operation, we are not aware of objective laxity data having been published previously for different follow-up times, despite concern that ACL reconstructions may stretch with time, leading to an insidious return of abnormal anterior-posterior
212
The Knee Vol. 2, No. 4, 1995
(A-P) knee laxity. A further objective was to examine the hypothesis that ACL reconstruction can protect the knee from osteoarthrosic changes: although it is wellknown that many chronic ACL-deficient knees suffer degeneration”~i6, there is little evidence to show that ACL reconstruction can prevent this, despite it being a major long-term aim of the surgery. Patients and methods We fully evaluated 74 patients (53 men and 21 women) who were operated on by a single surgeon (R.P.M.) using a standard operative technique between 1983 and 1993. The patients were an average age of 25 years at the time of surgery, with chronically ACL-deficient knees. The patients were evaluated as a whole (mean follow-up 4.1 years), and then divided into four groups according to their follow-up period (Table 1). The original injuries were the result of contact in 26 and a non-contract mechanism in 48 (Table 2). Football (soccer) was the sport most commonly related to the injury (Table 3). The indication for reconstruction was recurrent subjective instability, sometimes in everyday activities and in others only when they participated in a particular sport, which had failed to respond to physiotherapy. The pivot shift sign and the Lachman test were positive in all knees. Damage to the ACL was confirmed arthroscopically before further surgery. At that time procedures other than the ACL reconstruction were performed (Table 4). The operations were at an average time of 30 (range 2-84) months after the injury, using the technique described by Paterson and Trickey17, with the medial one-third of the patellar tendon used as an intraarticular graft. It was fixed ‘over the top’ under tension
Table
Group
1.
Study
(nl
A (12)
groups Mean follow up and range (years and months)
Age (years)
0.9 years ( 7-14 months) 2.3 (18-36) 4.5 (41-70) 8.5 (78-l 29)
B (28) c (20) D (14) Total:
74 Mean:
4.1
Table
2. Mechanism
26 27 30 32 Mean:
29
of injury
Contact Tackle from the back Direct blow or tackle at the lateral side Road traffic accident
26 5
Non-contact Twisting Hyperextension
48 43 5
18 3
Table
3. Sports-related
initial
injury
Football (soccer) Rugby football Netball Skiing Basketball Hockey Martial arts Running Squash Tennis Climbing
37 6 5 5 4 3 2 2 2 1 1
Total
68
Table
4. Other
surgical
procedures
related
to the initial
injury Procedure Medial Lateral
n meniscectomy meniscectomy
Total
23 (8 bucket 5 (2 bucket
handle) handle)
28
with the knee at 30” of flexion. This was supplemented by an extra-articular tenodesis as described by Galway, Beaupre and Macintosh”, and Ireland and Trickeyi’. All patients underwent the same postoperative rehabilitation programme. The leg remained in plaster at 15” knee flexion for 4 weeks, non-weight bearing, after which the patient was readmitted for treatment on a passive mobilization machine until 70” flexion had been achieved. Full weight bearing was permitted at 6 weeks and outpatient physiotherapy was continued with the use of a Cybex II isokinetic exercise machine for 3-8 months depending on patient requirements. Non-contact sport was allowed as soon as satisfactory muscle bulk was obtained, and contact sports were permitted 1 year after the repair. All 74 patients were reviewed clinically by T.D.Z., who had not been involved in their previous care or management. Assessmentmethods The patients were evaluated using a questionnaire including Lysholm and Tegner activity scores, physical examination, one-legged single hop test, KT-2000 arthrometry, lateral stressradiography measurements, and A-P tunnel-view weight-bearing radiographs. All tests were performed with the patient conscious. The range of flexion-extension was measured with a goniometer and compared with the uninjured knee. The anterior drawer, posterior sag, collateral stability, Lachman and pivot-shift tests, were also compared to the uninjured knee. These were graded as follows, compared to the uninjured knee: 0, the same; +l, O-5 mm extra movement; +2, 5-10 mm; +3, 10-15 mm; +4, >15 mm, apart from the pivot shift, which was graded as either present or absent”.
Zavras
The overall evaluation and the grading of the radiographs were based on the International Knee Documentation Committee (IKDC) Standard Ligament Evaluation Form”.
et al.: ACL reconstruction
with patellar
tendon
213
graft
test. The relationship between instrumented and radiographic laxity differences was examined using Spearman’s rank correlation coefficient. The correlation of lack of extension with overconstraint of the joint or a low Lysholm score was determined by the x2 test.
KT 2000 arthrometer Measurements were taken for both knees with the joint flexed between 20” and 30”. Starting with the leg in neutral rotation and the tibia resting posteriorly, a ‘manual maximum’ anterior drawer force was applied to the KT arthrometer, giving an anterior laxity reading in millimetres’“. This was repeated five times for both knees and a mean laxity difference calculated. Stress radiographs Lateral stress views of each knee were obtained with the patient supine and the knee flexed 20”. The calf was supported while a 5 kg sandbag plus the weight of the thigh caused the femur to fall posteriorly, stressing the ACL. The cassette was placed medially, with the X-ray tube 120 cm from the knee, and angled 5-8” distally23. Statistical analysis
Group A 8 c D
6. Subjective,
In)
(12)
(28) PO) (14)
Total:
74
means:
Ten patients were operated on again after the ACL reconstruction (Table 5). The KT-2000 and stressradiography methods of instability evaluation were correlated significantly (P < 0.01). However, we noticed that we had more than 2 mm difference between the methods in 11 cases.In 12 cases,including these 11, the lateral radiographs were considered unacceptable, since the distance between the posterior outlines of the condyles in the sagittal plane was more than 6 mm. We therefore based our analysis on the KT stability data. For the group as a whole, 91% had a negative pivot shift test, 58% had a side-to-side anterior laxity difference ~2 mm, and 88% had subjectively satisfactory results, with a Lysholm score greater than 76. Overall, acording to the IKDC evaluation, 77% had successful results. The results for the groups at different times are shown in Tables 6 and 7.
Linear regression analysis was used to evaluate the changes over time, and to examine the effect of the time interval between injury and operation, and between operation and review, on arthritic degenerative changes indicated by joint space narrowing. To test differences between groups we used the x2 test for the IKDC score and the pivot shift sign, and the unpaired t-test for the single hop. Differences in Tegner’s activity score before and after operation, and the differences of the Tegner and Lysholm scores between the postoperative groups were evaluated with the Wilcoxon
Table
Results
results
5. Surgical reconstruction
MUA Patella shaving Meniscectomies Removal of fixation
2 2 2 4
(imean values,
10
and overall
Follow up (years)
L ysholm score
Tejgner score
Single hop l% normal)
0.9 2.3 4.5 8.5
86.6 89.0 91.6 91.5
6 6.8 7 6.8
78.5 90.25 94.8 91
4.1
89.6
6.7
88.6
0.9 2.3 4.5 8.5 Mean:
4.1
Tegner
staple
Total
objective,
Lysholm
ACL
n
number
7. Follow up, % Lysholm scores 377, Tegner scores 36, % negative negative pivot shift signs, % IKDC scores ~2 (excellent and good results) up (years)
following
Procedure
Table
Follow
procedures
Table
Lachman
of positive
pivot signs)
Lachman (mm difference by KT-2000)
Pivot sign
IKDC score
0.33 0.82 2.81 4.41
0 2 2 2
2.33 2.28 1.95 2.25
2.09
6
2.2
Lachman
test (~2 mm side difference),
Pivot
IKDC
89 82 91 91
56 83 87 75
89 75 50 9
100 93 91 84
67 75 87 75
88
75
58
91
77
%
214
The
Knee
Vol. 2, No. 4, 1995
Table 6)) and there was no deterioration of performance between 2.3 and 8.5 years after operation. Range of knee motion
5 g 2 g s
Overall, 32 patients lacked full extension and 30 patients lacked full flexion. In group A the mean losses were 5” extension and 16” degrees flexion, while groups B, C and D lost a mean of 4” extension and 9” flexion. There was no significant relationship between lack of extension and either low Lysholm scores or overconstraint (P > 0.05).
35 30 25 20 15 IO 5 0
Figure 1. Side-to-side groups at different times 20” knee flexion.
Subjective evaluation Lysholm score The mean Lysholm score did not change significantly with time (P = 0.1, Table 6). anterior laxity after operation,
differences using KT2000
in at
Objective evaluation A-P Laxity The A-P laxity increased significantly as a function of postoperative time (P < 0.001; Table 6 and Figure 1). The side-to-side difference had a range from -3 mm to 8 mm, and increased by 4.1 mm between the groups at 0.9 and 8.4 years mean follow up (Table 6). In the first two groups, up to 3 years after operation, there were 16 overconstrained knee joints (35%), while there were none after this time. We did not find a significant correlation between overconstraint and either low Lysholm scores or loss of extension (0.1 > P > 0.05).
Tegner score The Tegner activity level score did not change significantly with time (P = 0.07), and never reached the preinjury or desired levels for each group of patients (P < 0.001, Table 8). Removing the patients with positive pivot and giving way did not change the significance of the difference between the preinjury and postoperative activity levels (P < 0.001). Overall, 47% of the individual patients, and 60% of those in group C (at 4.5 years mean follow up) had returned to the same Tegner activity level as before injury. Pivot shift test Six patients had a positive pivot shift test, two in each of the longer term follow-up groups, and there was no significant increase with time (P > 0.1). None of them had a gross subluxation and two doubtful cases were considered as positive.
Radiographic findings
Giving way
We classified the radiographic findings according to the IKDC2’. There was no significant change between the preoperative and follow-up radiographs, and hence no significant development of degenerative changes over the follow up time (P > 0.5). However, joint space narrowing and patellofemoral joint arthritic deterioration were correlated with the time between injury and operation (P = 0.02). The mean number of osteophytes at follow up was 1.9 (range O-7), and there was no significant correlation either with the interval between injury and operation, or between operation and last follow up (P > 0.05). In all cases but two the osteophytes appeared smaller than 5 mm.
Eight patients complained of giving way, with a frequency ranging from rarely during athletic activities to occasionally during daily activities. One was from the first group, three from the second, three from the
Table
8. The Tegner
activity Tegner
Group
A B
score activity
score
Before injury
After injury
Post-op
Desired
6 6.7 7 6.8
8.3 7.6 7.9 7.6
6.7
7.8
Single hop test
C
8.2 7.7 8
D
7.9
2.7 3.3 3.1 ,3.4
There was a significant difference between the first group of patients and the other groups (P = 0.03,
Total
8
3.2
Zavras
third, and one from the fourth; we elicited a positive pivot shift in four of them. Overall evaluation IKDC score The mean values and the percentage of excellent and good IKDC scores, are shown in Tables 6 and 7; there was no deterioration of the score with time (P = 0.12).
Discussion There has been very little work which has attempted to show how objective measurement of excessknee laxity varies with time, or how this laxity correlates with changes in knee function as the postoperative time increases. Sandberg and Balkfors” found no change in objective anterior knee laxity or return of a positive pivot-shift between 2 and 5 years post-operation, although the subjective Lachman test was positive in 87% at 5 years. Our study has the drawback of being a retrospective review, rather than a study of one set of patients studied prospectively for 11 years, but the patients were all operated-on by a single surgeon who did not change any detail of the procedure throughout. Although this study found a significant increase in ibP laxity with postoperative time, this progressive change did not correlate with function as assessedby the pivot shift and the patient’s activity level. The first 3 years of this reconstruction were characterized by the existence of overconstraint of .&P laxity, which disappeared afterwards. This overconstraint did not influence the perceptions of the patients (no correlation with knee pain, for example), nor did it reduce the range of joint motion significantly. Although it has been shown that overtightening of an ACL graft can cause malarticulation and increased forceszs, we did not observe significant radiographic changes after operation. In the group of patients followed-up for a mean of 4.5 years (range 41-70 months), the overconstrained joints had disappeared and the group as a whole was now becoming slacker than normal: our data suggest that the grafts stretched progressively with time. With a mean Lachman laxity difference of 2.8 mm most of our patients were still ‘almost normal’ according to the IKDC2’, and this was the time when the functional scores (Lysholm, Tegner and IKDC) were best (Table 6). Although this was the time when the largest proportion of patients (60%) were functioning at ‘their pre-injury activity levels, there was still a highlysignificant difference (P < 0.001) between the actual activity level of the group and that which was desire:dby them. In the group of patients at a mean of 8.4 years since the operation the graft had stretched further, and the joints presented a mean side-to-side laxity difference of 4.4 mm. Thus the laxity had increased by a rnean 4.1 mm over the 7.5 years between groups A anld D.
et al.: ACL reconstruction
with patellar
tendon
graft
215
Although there is no fixed relationship between laxity and ACL length, due to the inclination of the ACL, the laxity change represents approximately 10% graft elongation. However, the function of the knee joint still remained nearly normal, with. the patients having maintained the level of activity to a mean Tegner score of 6.8. The fact that only 14% of group D had a positive pivot shift means that 4.4 mm excess laxity in the sagittal plane (the mean for this group) is probably not enough to cause a pivot shift in the presence of a lateral extra-articular reconstruction. A number of authors have noted that there can be a discrepancy between the objective measurements commonly performed in the postoperative evaluation of ACL reconstructions and what the patient perceives of the knee’s function7,‘2*25.26. Both this and other studies”s,‘o,12,‘4 have found a greater discrepancy between subjective and objective estimation for the Lachman sign than for the pivot shift, which is, therefore, often taken to be the clinical sign that is most closely related to symptomatic instability. This suggests that functional stability depends on control of subluxation with a rotary component, rather than just straight anterior laxity. The question of whether an extra-articular reconstruction should be added to an intra-articular ACL reconstruction is a matter for debate. Although there are many studies of patients with one or other of these approaches, there are few studies where the different strategies have been compared. Overall, there is no consensusin the literature in favour of adding an extraarticular reconstruction: while Noyes and Barberz7 found that it gave significantly better results, Jensen et a1.28and Strum et al. 29 found no significant difference, Roth et aZ.30 found greater laxity with a combined reconstruction(i.e. adding the extra-articular procedure had compromised stability) and, while O’Brien et al.3’ found no significant difference in function, they did find a 40% occurrence of symptoms related to the lateral procedure. Amis and Scammell’3, in a biomechanical study, found that the additional procedure did not give a closer approach to normality than an intra-articular graft alone in knees with an isolated ACL lesion, but suggested that this conclusion might change in the event of stretching of the secondary restraints, that might give greater rotary instability, when the pivot-shift would be more prominent. The evidence of this review, in which the pivot-shift remained absent in 85% at 8.5 years follow up despite significant stretching of the intra-articular graft, suggests that there is a place for lateral extra-articular procedures in addition to the intra-articular repair for controlling anterolateral rotatory instability of the knee. The intra-articular graft was placed ‘over the top’ (OTT) of the lateral femoral condyle in this series, a method which is technically simpler than use of a transcondylar drill hole. Despite this, the OTT route has become less popular following the promotion of isometricity and intraosseous fixation. Comparing the tunnel and OTT procedures Jonsson et aZ? found the
216
The Knee Vol. 2, No. 4, 1995
OTT superior on subjective assessment,and found no difference on objective examination. Conversely, Kornblatt et ~1.~ found the tunnel method gave 69% with no pivot, versus 47% when operated by the OTT method. In an experiment on canine joints using a bovine tendon xenograft3’, the OTT method was clearly superior regarding the incidence of rupture: 17% versus 91% for the tunnel method. The literature, therefore, does not provide a case for either method being superior, and we are not aware of evidence that an OTT graft will stretch more than one placed around an isometric point. It is noteworthy that both intraarticular OTT reconstructions and extra-articular reconstructions that pass deep to the lateral collateral ligament tighten as the knee extends’3,24, controlling tibia1 subluxation best when the knee is in a functional stance posture. When the graft was positioned, the patellar fragment was always placed against the raw surface of the femur following periosteal elevation. This ensured bone-bone fixation at both ends of the graft, and means that the laxity increases must have derived from graft elongation. The data show that degenerative changes were highly correlated (P = 0.02) with the time between injury and operation, and this is supported by other studies in which up to 45% of knees with an untreated ACL became arthrosic in the long term”~“. We did not observe a trend of development of arthritic changes with postoperative time this is evidence that ACL reconstruction can provide protection against joint degeneration, and is a significant finding in relation to the long-term objectives of ACL surgery. In view of the detailed findings described above, it may be hypothesized that this protection derives from avoidance of giving-way, that might cause meniscal lesions, rather than maintenance of normal anterior laxity.
Amiel D., Kleiner JB, Roux RD. The phenomenon ‘ligamentization’. 6
Howe JG, Johnson RJ, Kaplan MJ, Fleming B, Jarvinen M. Anterior cruciate ligament reconstruction using quadriceps patellar tendon graft. Part 1. Longterm followup. Am J Sports Med 1991; 19: 447-457
7
JohnsonRJ, ErikssonE, HaggmarkT, Pope MH. Fiveto-ten year followup evaluation after reconstruction of the anterior cruciate ligament. Clin Orthop 1984; 183:
8
Kornblatt I, Warren RF, Wickiewicz TL. Long term
122-134 followup of anterior using the quadriceps 9
10 11
12
13
14
1.5
17 18 19
1 2 3 4
Butler DL, Noyes FR, Grood ES. Ligamentous restraints to anterior-posterior drawer in the human knee. J Bone Joint Surg [Am] 1980; 62A: 259-270 Arnoczky SP, Warren RF, Ashlock MA. Replacement of the anterior cruciate ligament using a patellar tendon allograft. J Bone Joint Surg /Am] 1986; 68A: 376-385 Amiel D, Kleiner JB, Akeson WH. The natural history of the anterior cruciate ligament autograft of patellar tendon origin. Am J Sports Med 1986; 14: 449-462 Noyes FR, Butler DL, Paulos LE. Grood ES. Intraarticular cruciate reconstruction. 1: Perspectives on graft strength, vascularization and immediate motion after replacement. Clin Orthop 1983; 172: 71-77
cruciate ligament reconstruction tendon substitution for chronic
anterior cruciate ligament insufficiency. Am J Sports Med 1988; 16: 444-448
16
References
of
cruciate ligament
reconstruction with autogenouspatellar tendon. J Orthop Res 1986; 4: 162-172
Acknowledgements We thank Mr Paul Aichroth and the Wellington Hospital knee surgery unit for the use of the KT arthrometer. We also thank Mrs E.J. Snell from the Imperial College Mathematics Department for her statistics advice.
Anterior
20
21
22
Rackemann S, Robinson A, Dandy DJ. Reconstruction of the anterior cruciate ligament with an intra-articular tendon graft and an extra-articular tenodesis. J Bone Joint Surg (BrJ, 1991;73B: 368-373 Sandberg R, Balkfors B. The durability of anterior cruciate ligament reconstruction with the patellar tendon. Am J Sports Med 1988; 16: 341-343 Shelbourne KD, Whitaker HJ, McCarroll JR, Rettig AC, Hirrshman LD. Anterior cruciate ligament injury: Evaluation of intraarticular reconstruction of acute tears without repair. Am J Sports Med 1990; 18: 484-489 Bray RC, Flanagan JP, Dandy DJ. Reconstruction for chronic anterior cruciate instability. A comparison of two methods after six years. J Bone Joint Surg [Br] 1988; 70B: loo-105 Amis AA, Scammell BE. Biomechanics of intraarticular and extra-articular reconstruction of the anterior cruciate ligament. J BoneJoint Surg [Br] 1993; 70B: 812-817 Dandy DJ, Gray AJR. Anterior cruciate ligament reconstruction with the Leeds-Keio prosthesis plus extra-articular tenodesis. Results after six years. J Bone Joint Surg [Br] 1994; 76B: 193-6 Noyes FR, Mooar PA, Matthews DS, Butler DL. The symptomatic anterior cruciate deficient knee. J Bone Joint Surg [Am] 1983; 65A: 154-162 Jacobsen K. Osteoarthrosis following insuffiency of the cruciate ligament in man. Acta Orthop Stand 1977; 48: 52c-526 Paterson FWN, Trickey EL. Anterior cruciate ligament reconstruction using part of the patellar tendon as a free graft. J Bone Joint Surg [Br] 1986; 68B: 453457 Galway RD, Beaupre A, Macintosh DL. Pivot-shift: a clinical sign of symptomatic anterior cruciate insufficiency. J Bone Joint Surg [Br] 1972;54B: 763 Ireland J, Trickey EL. Macintosh tenodesis for anterolateral instability of the knee. J Bone Joint Surg [Br] 1980; 62B: 34c345 Elmquist LG, Lorentzon R, Langstrom M, Fugl-Meyer AR. Reconstruction of the anterior cruciate ligament. Long-term effects of different knee angles at primary immobilization and different modes of early training. Am J Sports Med 1988; 16: 455460 Hefti F, Drobny T, Hackenbruch W. et al. Evaluation of knee ligament injuries: The OAK and IKDC forms. In: Jakob RP, Staubli HU, eds. The Knee and the Cruciate Ligaments.Berlin: Springer-Verlag, 1990: 134-139 Daniel DM, Stone ML. KT-1000 Anterior-posterior displacement measurements. In: Daniel D Akeson W, O’Connor J, eds. Knee ligaments.Structure, Function, Injury, and Repair. New York. Raven Press, 1990: 427-447.
Zavras
23
24
25
26
27
28
Staubli H-U, Jakob RP. Our current technique of stressradiography near extension. In: Jakob RP, Staubli HU, eds. The Knee and the Cruciate Ligaments. Berlin: Springer-Verlag, 1990: 177-183 Amis AA. Anterior cruciate ligament replacement knee stability and the effects of implants. J Bone .Joint Surg [Br] 1989; 71B: 819-824 Anderson C, Odensten M, Good L, Gillquist J. Surgical or non-surgical treatment of acute rupture of the anterior cruciate ligament. J Bone Joint Surg [Am] 1989; 71A: 965-974 Jonsson H, Elmqvist LG, Karrholm J, Tegner Y. Overthe-top or tunnel reconstruction of the anterior cruciate ligament? J Bone Joint Surg [Br] 1994; 76B: 82X7 Noyes FR, Barber SD. The effect of an extra-articular procedure on allograft reconstructions for chronic ruptures of the anterior cruciate ligament. J Bone Joint Surg [Am] 1991; 73A: 882-892 Jensen JE, Slocum DB, Larson RL, James SL, Singer KM. Reconstruction procedures for anterior cruciate
et al.:
29
30
ACL
reconstruction
with
patellar
tendon
graft
217
ligament insufficiency: A computer analysis of clinical results. Am J Sports Med 1983; 11: 240-248 Strum GM, Fox JM, Ferkel RD et al. Intraarticular versus intraarticular and extraarticular reconstruction for chronic anterior cruciate ligament instability. Clin Orthop 1989; 245: 188-198 Roth JH, Kennedy JC, Lockstadt H, McCallum CL, Cunning LA. Intra-articular reconstruction of the anterior cruciate ligament with and without extraarticular supplementation by transfer of the biceps femoris tendon. J Bone Joint Surg [Am] 1987; 69A: 275-278
31
32
O’Brien SJ, Warren RF, Wickiewicz TL et al. The iliotibial band lateral sling procedure and its effect on the results of anterior cruciate ligament reconstruction. Am J Sports Med 1991; 19: 21-25 Montgomery RD, Milton JL, Terry GC, McLeod WD, Madsen N. Comparison of over-the-top and tunnel techniques for anterior cruciate ligament replacement. Clin Orthop 1988; 231: 144-153