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Meniscal Repair
Current Concepts
Meniscal Repair Christian Stärke, M.D., Sebastian Kopf, M.D., Wolf Petersen, M.D., and Roland Becker, M.D.
Abstract: The meniscus plays an important role in preventing osteoarthritis of the knee. Repair of a meniscal lesion should be strongly considered if the tear is peripheral and longitudinal, with concurrent anterior cruciate ligament reconstruction, and in younger patients. The probability of healing is decreased in complex or degenerative tears, central tears, and tears in unstable knees. Age or extension of the tear into the avascular area are not exclusion criteria. Numerous repair techniques are available, and suture repair seems to provide superior biomechanical stability. However, the clinical success rate does not correlate well with the mechanical strength of the repair technique. Biologic factors might be of greater importance to the success of meniscal repair than the surgical technique. Therefore, the decision on the most appropriate repair technique should not rely on biomechanical parameters alone. Contemporary all-inside repair systems have decreased the operating time and the level of surgical skill required. Despite the ease of use, there is a potential for complications because of the close proximity of vessels, nerves, and tendons, of which the surgeon should be aware. There is no clear consensus on postoperative rehabilitation. Weight bearing in extension would most likely not be crucial in typical longitudinal lesions. However, higher degrees of flexion, particularly with weight bearing, give rise to large excursions of the menisci and to shear motions, and should therefore be advised carefully. Long-term studies show a decline in success rates with time. Further studies are needed to clarify the factors relevant to the healing of the menisci. Tissue engineering techniques to enhance the healing in situ are promising but have not yet evolved to a practicable level. Key Words: Age—Growth factors—Healing—Meniscus—Rehabilitation— Repair technique.
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linical evidence supports the hypothesis that meniscectomy leads to cartilage degeneration in men. Meniscectomy increases the risk of developing osteoarthritis (OA) of the knee significantly after more than 20 years.1 The extent of resection relates to the
From the Departments of Orthopaedic Surgery at Otto-vonGuericke University Magdeburg (C.S.), Magdeburg, Germany, and Pittsburgh University Medical Center (S.K.), Pittsburgh, Pennsylvania, U.S.A.; the Department of Trauma Surgery, Martin Luther Hospital (W.P.), Berlin, Germany; and the Department for Orthopaedic and Trauma Surgery, City Hospital Brandenburg (R.B.), Brandenburg, Germany. The authors report no conflict of interest. Address correspondence and reprint requests to Roland Becker, M.D., Department for Orthopaedic and Trauma Surgery, City Hospital Brandenburg, Hochstrasse 29, 14776 Brandenburg an der Havel, Germany. E-mail: [email protected] © 2009 by the Arthroscopy Association of North America 0749-8063/09/2509-8403$36.00/0 doi:10.1016/j.arthro.2008.12.010
degree of radiologic OA.2 These arguments suggest that meniscal repair should lead to an improved clinical outcome compared with meniscectomy. However, the results found in the literature are equivocal. Some authors have reported fewer radiologic symptoms of OA in patients who had their meniscus repaired compared with patients who underwent meniscectomy.3 Others failed to prove a substantial clinical benefit to repairing a meniscus.4 A number of case series reported high rates of clinical success of meniscal repair, but investigations with a strong study design are rare. The available data indicate that meniscal repair cannot reliably prevent the progression of degenerative changes and clinical symptoms. A potential explanation is that both meniscal lesions and cartilage damage occur as different features of the same entity, which is not cured by repairing the meniscus. Indeed, there is evidence that meniscal pathology occurs not
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 25, No 9 (September), 2009: pp 1033-1044
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only as a cause but also as a symptom of OA of the knee.5 It seems possible that the fate of a repaired meniscal lesion depends largely on its nature: namely, whether it is degenerative or traumatic in origin. Nonetheless, meniscectomy is an irreversible procedure. Neither replacement nor regeneration of the meniscus have yet evolved to a satisfactory level. It is therefore reasonable to prefer repairing the meniscus to removing it. BLOOD SUPPLY AND TEAR LOCATION In adults, only the peripheral 10% to 25% of the meniscus is vascularized (Fig 1).6 In normal tissue repair, local bleeding provides cellular elements and biochemical mediators that are essential for the repair response. It is therefore generally believed that it is the missing vascular supply that limits the healing capability of the central zones. However, it was shown in animal explant culture models that meniscal tissue is capable of a repair response in the absence of vascularity.7 In a clinical study of 198 meniscal repairs that extended into the avascular zone, 80% remained asymptomatic at follow-up.8 Kalliakmanis et al.9 did not find a significant difference between tears located in the red–red zone and tears in the red–white zone.9 Cannon and Vittori10 found a substantial drop in the healing rates if the rim width exceeded 4 mm in stable knees. Tears located mainly in the central zone have an inferior healing capability.11 So far, it has not been established if the locally different healing response is solely a matter of the vascular supply. Mechanical stress, for instance, may influence the behavior of cells populating the meniscus. The chance of healing is increased if the tear
FIGURE 1. Blood supply of an adult’s meniscus. Note that only the peripheral 10% to 25% of the meniscus is vascularized from the perimeniscal plexus.
FIGURE 2. Menisci with circumferential and radial Cooper zones. Zones 0 and 1 are considered peripheral and are associated with a better healing capability.
either is located in the vascularized area or if access to blood elements is created. Therefore, most surgeons limit repair to lesions located in the Cooper zones12 1 and 2 (Fig 2). Nevertheless, an extension of the tear into the avascular area is not an exclusion criterion. In select patients, such as young athletes, the chance of healing probably outweighs the potential risks of the procedure.13 Tear Pattern and Shape Meniscal lesions are generally more common in males.14 Metcalf and Barrett15 investigated tear patterns in a large number of patients with stable knees; 39% were peripheral tears (Cooper zone 1 or 2). The majority of tears occurred in the posterior horns, with 73% being isolated medial tears and 19% isolated lateral tears. Horizontal tears were most common in this study, followed by complex and flap tears. Longitudinal and bucket-handle tears were found in 19% of cases. In a similar study that investigated patients with an anterior cruciate ligament (ACL) rupture, the portion of lateral meniscal tears increased to 50% in acute cases.16Again, most tears were located in the posterior horns. Peripheral tears (Cooper zones 1 and 2) were found in more than 60% of cases. The probability of encountering tears suitable for repair is substantially decreased in stable knees compared with ligament injured knees. If repaired, double longitudinal or complex tears have a higher probability for failure.8 Tears that involve only the posterior segment seem to have an inferior healing rate compared with lesions extending into the middle segments.17
MENISCAL REPAIR Horizontal cleavage tears are a frequent finding and may exist without clinical symptoms.18 There is little information on the significance of this type of tear. They can give rise to flap tears but are otherwise mechanically stable. It has not been clarified yet whether patients benefit from the repair of these tears. It appears questionable if sutures could neutralize the shear motion that is thought to be responsible for the development of these tears. If horizontal tears are encountered incidentally— during ACL surgery, for example—they might be left alone. At times, those tears are accompanied by meniscal cysts,19 which are thought to arise from the influx of joint fluid through meniscal tears. Partial meniscectomy is often carried out to drain the cyst. It has been suggested that aspiration of the cyst and closure of the tear with sutures could avoid the need for a meniscectomy.20 Controversy exists concerning radial tears. They should be clearly distinguished between complete and partial radial tears. Empirically, partial radial tears often affect the central parts while the outer rim remains intact. This has important mechanical implications: in partial radial tears, the important circumferential fiber bundles are mostly intact and the function of the meniscus is retained. Further, those tears largely extend into the avascular area, which limits the chance of healing.21 Therefore, particularly in small radial tears, debridement of loose edges is usually sufficient. In cases of a complete trans-section, however, the effect can be similar to a complete meniscectomy.22 If left untreated, weight bearing would extrude the meniscus out of the joint space and most likely no functionally sufficient healing would occur. Although it has been found that lateral meniscal tears in conjunction with ACL tears seem to have good prognosis in general,23 some surgeons24 including the authors of this review, feel that it might be beneficial to approximate and secure the tear margins of a complete tear with sutures. In those cases, non–weight bearing exercise is warranted postoperatively because circumferential stress (so-called “hoop stress”) is induced in the meniscus with tibiofemoral loads, which would distract the tear margins. The influence of the tear length on the failure rate is not entirely clear. Although some authors could not prove an association between the failure rate and the length of the tear,11 others found that failures occurred significantly earlier in larger tears.25 In one study, the healing rate was in excess of 90% if the length of the tear was less than 2 cm, whereas it was only 50% with tears larger than 4 cm.10
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Medial Versus Lateral Lesions In a series of 53 patients, no significant difference in the healing rate was found by means of computed tomographic arthrography for the medial and lateral meniscus.17 Cannon and Vittori10 found lateral menisci to have a better healing rate than medial menisci. Another investigation into ACL-reconstructed knees did not find different failure rates for lesions located in the Cooper zones 1 and 2 of either the medial or lateral meniscus.26 It is not entirely clear whether or not the healing potential in the medial and lateral meniscus are different. Yet the potential sequelae of meniscectomy are more serious in the lateral meniscus than in the medial.2 Therefore, in the decision-making process, it matters which of the menisci is affected. Influence of Age It has been observed that meniscal tissue from patients over 40 years of age has a lesser cellularity and a decreased healing response than tissue from younger patients.27 Eggli et al.28 stratified their patients into groups older and younger than 30 years and found retears to be more frequent in older patients. Bach et al.25 analyzed failures in a series of 300 meniscal repairs.25 The average time to failure was 34 months in this study. Older patients failed significantly later than patients younger than 30 years of age. Other investigators did not find a correlation between the revision rate and patient age in 113 cases of an allinside repair using the Meniscus Arrow (Conmed Linvatec, Largo, FL).29 In a recent study, the results of meniscal repair in patients with reconstructed ACLs are reported, and in terms of failures, no difference was found between patients older or younger than 35 years of age.9 The rates of clinical success in repair procedures, which involve the avascular area, seem not to be worse in older patients (40 to 58 years) compared with the younger population.8,30 The outcome of repair in young patients is not generally favorable, as one might expect.31 By means of arthrography or magnetic resonance imaging, it was shown that healing of repaired tears remained incomplete in a high fraction of young patients, even in the absence of symptoms.31 The same negative prognostic factors as in older patients, such as a complex tear configuration, large distance to the periphery, or ligamentous instability, apply to the younger patients.32 Obviously, the clinical results in younger patients are in conflict with the better intrinsic healing capability that the basic science suggests. First, there are no randomized controlled studies in which the treatment
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1036 TABLE 1.
Overview of Meniscal Repair Instruments and Implants
Suture ●
●
●
Inside-out (generic flexible needles and prebent cannulas) Outside-in (generic intravenous cannulae) All-inside (Meniscal Viper [Arthrex])
Suture Repair Systems
Rigid Implants ●
● ●
●
Meniscus Arrow (Conmed Linvatec) Meniscal Dart (Arthrex) BioStinger (Conmed Linvatec) Meniscal Screw (Biomet)
●
● ● ●
FasT-Fix (Smith & Nephew Endoscopy) MaxFire (Biomet) Meniscal Cinch (Arthrex) RapidLoc (DePuy Mitek)
allocation is primarily based on patient age. Most investigators will consider the macroscopic appearance of the meniscus in their treatment decision and would not repair tears in grossly degenerated menisci. This results in a selection bias, which potentially obscures the influence of the patient’s age. Further, higher demands in sports and occupation in the young population might compromise the outcome despite a better intrinsic healing capability. The available data suggest that age is not a general contraindication to meniscal repair—it merely increases the likelihood of encountering a tear that is not suitable for repair.15
ing time and problems to reach the far posterior regions of the meniscus. Therefore, implants to be used without the need for additional incisions (all-inside) were developed. The first generation of those allinside systems were small rigid implants with barbs or threads, usually made from absorbable polymers. In addition to occasional mechanical complications, most of the solid all-inside implants show a considerable inferior stiffness and failure load, partially less than 10 N.38,39 In an effort to provide the convenience of the rigid implants while giving the strength of suture repair, combinations of sutures and rigid parts were developed (Table 1; Figs 3–5). While the FasTFix (Smith & Nephew Endoscopy, Andover, MA) implant was the first of its kind, all major suppliers of arthroscopic equipment now offer devices with a similar design. Table 2 shows the rates of clinical success for a variety of repair techniques and implants. It should be noted that partial healing or failure of heal-
CHOICE OF THE REPAIR TECHNIQUE A central question for the surgeon is whether the healing response and long-term outcome depends on the technique that is used. Horizontal sutures usually yield a lower failure load because they lie in between the circumferential fiber bundles and are pulled through those as they are loaded.33 Vertical sutures are commonly considered the gold standard in regard to the strength, which was found to be in a range from about 60 N to more than 200 N, depending on the investigated model.34,35 In the case of vertical sutures, failure occurs mainly by rupture of the suture because the strong circumferential fiber bundles of the meniscus are contained within the suture loop. Here, the choice of the suture material determines the failure load.36 In general, vertical sutures are preferred to horizontal stitches; the techniques are very similar, but vertical sutures result in stiffer repairs. Variations, with the limbs of the suture crossing each other, further increase the failure load.37 Conventional suture techniques are afflicted with a relatively long operat-
FIGURE 3. Bioresorbable implants. (A) Meniscus Arrow (Conmed Linvatec). (B) Meniscal Dart (Arthrex). (C) BioStinger (Conmed Linvatec).
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lesions.40,41 Shear forces might be more relevant but are not addressed in most studies investigating the stability of repair systems. The success rates for the Meniscus Arrow and conventional sutures seem to drop with time (Table 2). Because there are no long-term studies for the newer implants, the false impression might arise that those are more successful than sutures or the Arrow. It is possible that the same decline in the healing rate will take effect with a longer follow-up of those systems. COMPLICATIONS AND PITFALLS OF MENISCAL REPAIR Bleeding or pseudoaneurysms descending from popliteal vessels are described with arthroscopic meniscal surgery. But those reports almost exclusively pertain to the resection of the posterior horns,42,43 not meniscal repair. In a cadaver study, it was found that the lateral genicular artery is at risk of being penetrated by the needle with inside-out and outside-in sutures of the lateral meniscus (Fig 6). However, it has not yet been established whether a laceration of this vessel has detrimental effects on the healing meniscus. Capture of branches of the peroneal nerve is possible when lateral meniscal lesions are sutured, but seems to be rather seldom. Proper use of retractors can largely avoid this complication.44 In the case of medial meniscal repair, the saphenous vein and nerve are at risk of being affected.45 Although transient neuro-
FIGURE 4. All-inside suture repair systems. (A) FasT-Fix (Smith & Nephew Endoscopy). (B) MaxFire (Biomet). (C) Meniscal Cinch (Arthrex). (D) RapidLoc (DePuy Mitek).
ing does not necessarily cause clinical symptoms.8 Therefore, rates of so-called clinical healing do not exactly reflect the healing status in a structural sense. Further, the clinical success rates do not correspond closely to the magnitudes of the mechanical strength that is found for the different repair techniques38 (Table 2). The available data do not support the assumption that stronger repair techniques are accompanied by better outcomes. It must be acknowledged that mechanical testing is usually done in the axis of insertion, although it has not been shown conclusively that substantial distraction forces do occur on repaired
FIGURE 5. Instruments for suture repair. (A) Meniscal Viper (Arthrex). (B) Prebent cannula, nitinol needle (Arthrex).
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1038 TABLE 2. Author Albrecht-Olsen et al.51 Pujol et al.17 Cannon and Vittori10 Kocabey et al.77 Barrett et al.87 Marinescu et al.88 Hürel et al.89 Kotsovolos et al.90 Frosch et al.76 Venkatachalam et al.91 Petsche et al.92 Haas et al.93 Tsai et al.94 Kalliakmanis et al.9 Barber et al.95 Gill and Diduch96 Spindler et al.97 Billante et al.98 Barber et al.99 Ellermann et al.100 Noyes and Barber-Westin30 Quinby et al.101 Barber and Coons102 Rubman et al.8 Kurzweil et al.103 Kurosaka et al.104 Gifstad et al.105 Koukoulias et al.106 Lee and Diduch107 Eggli et al.28 Majewski et al.108
Summary of Outcomes for Different Repair Techniques and Systems
No. of Follow-up Concurrent Effect of Meniscal Cases Time (mo) ACLR ACLR Arrow Screw T-Fix FasT-Fix RapidLoc BioStinger Suture 65 50 90 55 21 68 26 61 40 62 29 42 26 265 89 32 125 38 32 105
3 6 7-10 10.3 12 12 16.7 18 18 21 24 24.3 24.5 24.5 26.5 27 68/27 30.4 31 33
Some Majority Majority Majority All Some Some Majority Majority Some Majority Majority Some All Majority All All All Majority Majority
— None Better — — — — None Better Better — Better — — — — — — None None
91 — — — — — 88 — — 56 93 — — — — 90.6 89 — — 80
— — — — — — — — 100 (82) — — — 78 — — — — — — —
— — — 96 81 — — — — 57 — — — 89.4 — — — — — —
— 82 — — — — — 90.2 — — — 86 — 92.4 — — — — — —
— — — — — — — — — — — — — 86.3 — — — 86.8 87.5 —
— — — — — — — — — — — — — — 91 — — — — —
75 — 93 (50) — — 94 — — — 78 — — — — 100 — 88 — — —
30 54 41 198 60 114 118 11 28 52 116
34 34.8 36.8 42 54 13/54 56.4 73 79.2 90 120
Majority All Majority Majority Majority Majority Some None All None None
Better — — — Better — None — — — —
— — — — 72 — 59 72.7 71.4 — —
— — — — — — — — — — —
— — — — — — — — — — —
— — — — — — — — — — —
— 90.7 — — — — — — — — —
— — 95 — — — — — — — —
87 — — — — 68 — — — 73 76
NOTE. The criteria for success are heterogenous. Most authors shown in Table 2 define failure as the need for repeat arthroscopy or symptoms of locking and catching. Table 2 is sorted by length of follow-up time, from the shortest amount of time at the top to the longest amount of time at the bottom. Whether or not the anterior cruciate ligament was reconstructed is given and, if applicable, the impact on the outcome. Numbers in parentheses give the outcome for the subgroup with unstable knees. It should be noted that there is a general trend of increasing failure rates with time. Meniscal repairs in anterior cruciate ligament–reconstructed knees have better results than repairs in primary stable knees or unstable knees. Abbreviation: ACLR, anterior cruciate ligament reconstruction.
praxia was described in up to 22% of cases,46 permanent damage was found to occur in 0.4% to 1%.47,48 An anatomic study that investigated the placement of the T-Fix (Smith & Nephew Endoscopy) device showed that neurovascular structures seem not to be at risk of being pierced with the insertion cannula.49 In a more recent investigation, the authors found that the application cannula of a FasT-Fix device came within 3 mm of the popliteal artery under certain circumstances, whereas the RapidLoc (DePuy Mitek, Raynham, MA), with its shorter cannula, had a greater distance to that vessel.50 The use of the depth limiter that comes with the FasT-Fix is therefore recom-
mended. However, Kalliakmanis et al.9 reported no neurovascular complications in a larger series of repairs using the T-Fix and FasT-Fix implants. In the case of solid implants, the depth of penetration can usually be controlled by choosing an implant of appropriate length. Nevertheless, cases of nerve damage have been described.51,52 A complication that is less dramatic than neurovascular damage and may thus be under-recognized is accidental soft tissue tenodeses. Anatomic studies have shown, for example, that the sartorius tendon, the deep medial collateral ligament, and the popliteus tendon are at risk of being penetrated by the application cannula (Fig 7).45,49 Al-
MENISCAL REPAIR
FIGURE 6. Coronal magnetic resonance imaging slice illustrating the close anatomic relationship of the inferior lateral genicular artery (ILGA) and the lateral meniscus. The vessel is at risk when passing needles/sutures inside-out or outside-in. (LCL, lateral collateral ligament)
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seem to improve the healing in animal models58 and in humans.59 It is postulated that the clot serves as a chemotactic and mitogenous stimulus. Some investigators succeeded in enhancing the healing of meniscal lesions with the application of mesenchymal stem cells.60 It is not clear whether this is a direct action of the progenitor cells or is rather mediated by secretion of certain stimulating factors. The behavior of meniscal fibrochondrocytes can be modulated when the cells are exposed to certain growth factors.61 The response to mitogenic stimuli, however, seems not to be necessarily the same for all regions.62 Human menisci are populated by cells of different phenotypes that might respond differently to extrinsic stimuli, as was reported by Verdonk et al.63 There are study findings showing that trephination or rasping alone without suturing the meniscus might be a reasonable option in stable tears. Shelbourne and Heinrich23 and Shelbourne and Rask64 published clinical studies investigating the fate of stable lesions in the medial and lateral meniscus that were either left alone or treated by rasping and trephination in conjunction with an ACL reconstruction. They found that only a minor proportion of their patients required subsequent surgery for their meniscus. Fox et al.65 reported on a similar procedure with good or excellent
though the results are not as severe as lacerations of the nerves or vessels, increased postoperative pain may compromise and slow down rehabilitation. Complications specific to solid repair devices are migration or breakage of the implant.53 Parts of the implants that surmount the surface of the meniscus can also wear down the cartilage in the contact zones and cause chronic synovitis.54 Although this has been addressed by changes in the design and resorption time of the implants, it seems that these problems are not fully eliminated.55 ENHANCEMENT OF THE HEALING RESPONSE Biologic factors might be of greater importance to the success of meniscal repair than the choice of the surgical technique. The healing potential apparently coincides with the vascular supply of the meniscal tissue.56 However, the local application of vascular endothelial growth factor did not lead to improved healing in a sheep model.57 Exogenous fibrin clots
FIGURE 7. Transverse magnetic resonance imaging slice of a knee at the height of the tibiofemoral joint space. Structures potentially at risk of being penetrated by a cannula or being caught by a suture are shown. (LCL, lateral collateral ligament; MCL, medial collateral ligament)
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results in about 90% of cases. Zhang and Arnold66 and Zhang et al.67 have shown in animal studies that trephination enhances the healing capacity of lesions in the avascular zone with and without additional sutures. INFLUENCE OF CONCURRENT INJURIES An injury to the ACL is the most often described entity encountered together with a meniscus tear. While the classic description of the O’Donoghue triad comprises a lesion of the medial meniscus together with a rupture of the ACL and medial collateral ligament, Barber68 and Shelbourne and Nitz69 have pointed out that lesions of the lateral meniscus are much more common in acute injuries. In chronic ACL deficiency, the relation shifts toward the medial meniscus.16,70 It has been shown that an abnormal anteroposterior laxity increases the resultant forces in the medial meniscus.71 The meniscus becomes a secondary stabilizer, a purpose for which it is not primarily made. Accumulated microdamage explains the increasing rates of medial meniscal lesions in the course of untreated ACL deficiency. Conclusively, meniscal repair should result in a better outcome if it is done in conjunction with a stabilization of the knee. There have been no randomized studies that have investigated the outcome of meniscal repair in relation to the ACL state. Usually, the anteroposterior instability will be regarded as the primary problem, and randomization in terms of the ACL reconstruction is not an option. Nevertheless, there are some studies that comprise subgroups of patients with either ligamentous intact, reconstructed, or unstable knees. In the majority of these studies, it seems that the outcome of a repair is better with concomitant reconstruction than in knees that remain unstable72-74 or even better than knees without ACL injury.75-77 The fact that meniscal repair appears to be more successful in combination with an ACL reconstruction deserves some detailed reflection. The simplest explanation is that, with the stabilization of the knee, the inciting cause for the repeated microtrauma of the menisci is eliminated, or at least diminished. Moreover, marrow elements are introduced into the joint cavity with the ACL procedure that, as described earlier, are thought to modulate the healing response of meniscal fibrochondrocytes. Another potential explanation for a seemingly improved healing rate with concurrent ACL surgery is related to patient selection. It must be assumed that in the subgroup of patients
with concomitant ACL reconstruction, the main reason for the procedure is instability, and that conclusively not only symptomatic but also clinically silent lesions of the meniscus are identified and repaired. However, in patients with stable knees, the cause for the meniscal repair usually is meniscal symptoms, such as locking or effusion. The possibility of a selection bias must therefore be considered. REHABILITATION Patients should be informed in advance that meniscal repair is usually accompanied by much longer periods of restricted motion and limitation of the knee function than after a meniscectomy. It has been shown that the reparability of meniscal tears can be predicted reasonably well by magnetic resonance imaging studies,78 which gives both the patient and surgeon the opportunity to be prepared in advance. A generally valid rehabilitation algorithm has not been established. Rehabilitation plans need to be individually tailored and should take into consideration the nature of the tear, concurrent injuries and procedures, and the influence of specific exercises on the repaired tear (Table 3). There are both mechanical and biologic effects associated with postoperative weight bearing and motion of the knee. In repaired bucket-handle lesions, weight bearing reduces the meniscus and stabilizes the tear.40 Flexion under tibiofemoral loads of the knee, however, leads to increasing compressive and shear loads in the posterior horn. It was reported that weight bearing flexion from full extension to 90° increases the pressure on the posterior horn by, roughly, a factor of 4.79 The menisci translate dorsally with knee flexion. This motion depends not only on the flexion angle but also on the weight bearing condition.80 The magTABLE 3.
Postoperative Rehabilitation Program for a Typical Bucket-Handle Lesion
Early Phase ● ● ● ● ●
Ice and analgesics Crutches as needed Brace to limit motion Partial or full weight bearing Non–weight bearing motion (60° to 90°)
Intermediate Phase
Late Phase ● ●
● ● ● ●
Aqua jogging Isometric strength training Continue brace No squats for 12⫹ wks
●
Regain full range of motion Strength training Consider modification of activities if related to development of tear
NOTE. Patients might need an individually tailored program.
MENISCAL REPAIR nitude of the posterior femoral rollback, and necessarily the posteriorly directed translation of the menisci, is substantially increased in the weight-loaded knee compared with the unloaded state. Although this was not directly proven by the cited study, motion exercises of the knee without weight bearing might therefore be preferable during rehabilitation to limit the stress on the repair. Weight bearing in extension most likely does not pose a problem to repaired meniscal lesions. An exception to this is complete transections of circumferential fiber bundles of the meniscus, such as radial tears that comprise the whole cross-section or posterior root tears. In those cases, weight bearing would be deleterious because the hoop stress distracts the tear margins and healing is prevented.81 Tibial rotation causes large excursions of the meniscus within the first 30° of flexion.82 Terminal flexion is accompanied by a large dorsal translation of the condyles and causes increased compressive stress of the meniscus.79,80 Therefore, deep squats and tibial rotation should be avoided for at least 12 weeks. Although the magnitude of the posterior translation of the medial and lateral meniscus is different, no significant difference in the pressure that arises on the medial and lateral posterior horns was found by Becker et al.79 at up to 90° of flexion. So far, it is not clear if medial and lateral meniscal repairs deserve different rehabilitation protocols. Most investigations about the biologic effects of immobilization found that it impaired the healing of repaired menisci.83 Limited motion and weight bearing in full extension might have stimulating effects on the healing response.84 There have been some clinical investigations regarding the effect of a more aggressive rehabilitation of meniscal repair patients. Barber and Click46 and Barber85 did not find any evidence that an accelerated program compromises the result of the repair. Similarly, Mariani et al.86 failed to show deleterious effects when patients with concomitant ACL surgery were subjected to an accelerated rehabilitation program. However, the design and case number of those studies do not allow one to infer in general that restrictions after meniscal repair are not necessary. CONCLUSIONS Meniscal preservation has gained a high level of awareness in the recent years. The surgeon must consider the nature of the tear in his decision of whether or not to repair or resect. The prognosis of a meniscal repair is better if it is possible to identify and treat an underlying problem like an ACL deficiency. Contem-
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porary all-inside repair systems have significantly decreased the level of technical skills required for a successful repair. There is currently no scientifically substantiated reason to believe that the choice of a particular repair technique would improve the outcome. It has not been shown thus far that a high failure load is associated with better clinical results.
REFERENCES 1. Roos H, Laurén M, Adalberth T, Roos EM, Jonsson K, Lohmander LS. Knee osteoarthritis after meniscectomy: Prevalence of radiographic changes after twenty-one years, compared with matched controls. Arthritis Rheum 1998;41: 687-693. 2. Englund M, Lohmander LS. Risk factors for symptomatic knee osteoarthritis fifteen to twenty-two years after meniscectomy. Arthritis Rheum 2004;50:2811-2819. 3. Sommerlath KG. Results of meniscal repair and partial meniscectomy in stable knees. Int Orthop 1991;15:347-350. 4. Shelbourne KD, Carr DR. Meniscal repair compared with meniscectomy for bucket-handle medial meniscal tears in anterior cruciate ligament-reconstructed knees. Am J Sports Med 2003;31:718-723. 5. Englund M, Lohmander LS. Patellofemoral osteoarthritis coexistent with tibiofemoral osteoarthritis in a meniscectomy population. Ann Rheum Dis 2005;64:1721-1726. 6. Arnoczky SP, Warren RF. Microvasculature of the human meniscus. Am J Sports Med 1982;10:90-95. 7. Hennerbichler A, Moutos FT, Hennerbichler D, Weinberg JB, Guilak F. Repair response of the inner and outer regions of the porcine meniscus in vitro. Am J Sports Med 2007;35: 754-762. 8. Rubman MH, Noyes FR, Barber-Westin SD. Arthroscopic repair of meniscal tears that extend into the avascular zone. A review of 198 single and complex tears. Am J Sports Med 1998;26:87-95. 9. Kalliakmanis A, Zourntos S, Bousgas D, Nikolaou P. Comparison of arthroscopic meniscal repair results using 3 different meniscal repair devices in anterior cruciate ligament reconstruction patients. Arthroscopy 2008;24:810-816. 10. Cannon WD, Vittori JM. The incidence of healing in arthroscopic meniscal repairs in anterior cruciate ligament–reconstructed knees versus stable knees. Am J Sports Med 1992; 20:176-181. 11. Kimura M, Shirakura K, Hasegawa A, Kobuna Y, Niijima M. Second look arthroscopy after meniscal repair. Factors affecting the healing rate. Clin Orthop Relat Res 1995;314:185191. 12. Cooper DE, Arnoczky SP, Warren RF. Meniscal repair. Clin Sports Med 1991;10:529-548. 13. Noyes FR, Barber-Westin SD. Arthroscopic repair of meniscal tears extending into the avascular zone in patients younger than twenty years of age. Am J Sports Med 2002; 30:589-600. 14. Dandy DJ. The arthroscopic anatomy of symptomatic meniscal lesions. J Bone Joint Surg Br 1990;72:628-633. 15. Metcalf MH, Barrett GR. Prospective evaluation of 1485 meniscal tear patterns in patients with stable knees. Am J Sports Med 2004;32:675-680. 16. Smith JP, Barrett GR. Medial and lateral meniscal tear patterns in anterior cruciate ligament-deficient knees. A prospective analysis of 575 tears. Am J Sports Med 2001;29:415-419. 17. Pujol N, Panarella L, Selmi TAS, Neyret P, Fithian D, Beaufils
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P. Meniscal healing after meniscal repair: A CT arthrography assessment. Am J Sports Med 2008;36:1489-1495. Noble J. Lesions of the menisci. Autopsy incidence in adults less than fifty-five years old. J Bone Joint Surg Am 1977;59: 480-483. Barrie HJ. The pathogenesis and significance of menisceal cysts. J Bone Joint Surg Br 1979;61:184-189. Lu K. Arthroscopic meniscal repair and needle aspiration for meniscal tear with meniscal cyst. Arthroscopy 2006;22: 1367.e1-1367.e4. Weiss CB, Lundberg M, Hamberg P, DeHaven KE, Gillquist J. Non-operative treatment of meniscal tears. J Bone Joint Surg Am 1989;71:811-822. Lee SJ, Aadalen KJ, Malaviya P, et al. Tibiofemoral contact mechanics after serial medial meniscectomies in the human cadaveric knee. Am J Sports Med 2006;34:1334-1344. Shelbourne KD, Heinrich J. The long-term evaluation of lateral meniscus tears left in situ at the time of anterior cruciate ligament reconstruction. Arthroscopy 2004;20:346351. Yoo JC, Ahn JH, Lee SH, Lee SH, Kim JH. Suturing complete radial tears of the lateral meniscus. Arthroscopy 2007; 23:1249.e1-1249.e7. Bach BR, Dennis M, Balin J, Hayden J. Arthroscopic meniscal repair: Analysis of treatment failures. J Knee Surg 2005; 18:278-284. Kalliakmanis A, Zourntos S, Bousgas D, Nikolaou P. Comparison of arthroscopic meniscal repair results using 3 different meniscal repair devices in anterior cruciate ligament reconstruction patients. Arthroscopy 2008;24:810-816. Mesiha M, Zurakowski D, Soriano J, Nielson JH, Zarins B, Murray MM. Pathologic characteristics of the torn human meniscus. Am J Sports Med 2007;35:103-112. Eggli S, Wegmüller H, Kosina J, Huckell C, Jakob RP. Long-term results of arthroscopic meniscal repair. An analysis of isolated tears. Am J Sports Med 1995;23:715-720. Siebold R, Dehler C, Boes L, Ellermann A. Arthroscopic all-inside repair using the Meniscus Arrow: Long-term clinical follow-up of 113 patients. Arthroscopy 2007;23:394-399. Noyes FR, Barber-Westin SD. Arthroscopic repair of meniscus tears extending into the avascular zone with or without anterior cruciate ligament reconstruction in patients 40 years of age and older. Arthroscopy 2000;16:822-829. Accadbled F, Cassard X, Sales de Gauzy J, Cahuzac JP. Meniscal tears in children and adolescents: Results of operative treatment. J Pediatr Orthop B 2007;16:56-60. Krych AJ, McIntosh AL, Voll AE, Stuart MJ, Dahm DL. Arthroscopic repair of isolated meniscal tears in patients 18 years and younger. Am J Sports Med 2008;36:1283-1289. Rimmer MG, Nawana NS, Keene GC, Pearcy MJ. Failure strengths of different meniscal suturing techniques. Arthroscopy 1995;11:146-150. Dervin GF, Downing KJ, Keene GC, McBride DG. Failure strengths of suture versus biodegradable arrow for meniscal repair: An in vitro study. Arthroscopy 1997;13:296-300. Rankin CC, Lintner DM, Noble PC, Paravic V, Greer E. A biomechanical analysis of meniscal repair techniques. Am J Sports Med 2002;30:492-497. Post WR, Akers SR, Kish V. Load to failure of common meniscal repair techniques: Effects of suture technique and suture material. Arthroscopy 1997;13:731-736. Abdelkafy A, Wlk M, Krasny C, Landsiedl F. The “cruciate suture” for arthroscopic meniscal repair: A new technique. Arthroscopy 2006;22:1134.e1-1134.e5. Barber FA, Herbert MA, Richards DP. Load to failure testing of new meniscal repair devices. Arthroscopy 2004;20:45-50. Becker R, Schröder M, Stärke C, Urbach D, Nebelung W. Biomechanical investigations of different meniscal repair im-
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plants in comparison with horizontal sutures on human meniscus. Arthroscopy 2001;17:439-444. Richards DP, Barber FA, Herbert MA. Compressive loads in longitudinal lateral meniscus tears: A biomechanical study in porcine knees. Arthroscopy 2005;21:1452-1456. Becker R, Brettschneider O, Gröbel K, von Versen R, Stärke C. Distraction forces on repaired bucket-handle lesions in the medial meniscus. Am J Sports Med 2006;34:1941-1947. Jeffries JT, Gainor BJ, Allen WC, Cikrit D. Injury to the popliteal artery as a complication of arthroscopic surgery. A report of two cases. J Bone Joint Surg Am 1987;69:783-785. Tawes RL, Etheredge SN, Webb RL, Enloe LJ, Stallone RJ. Popliteal artery injury complicating arthroscopic menisectomy. Am J Surg 1988;156:136-138. Deutsch A, Wyzykowski RJ, Victoroff BN. Evaluation of the anatomy of the common peroneal nerve. Defining nerve-atrisk in arthroscopically assisted lateral meniscus repair. Am J Sports Med 1999;27:10-15. Espejo-Baena A, Golano P, Meschian S, Garcia-Herrera JM, Serrano Jiménez JM. Complications in medial meniscus suture: A cadaveric study. Knee Surg Sports Traumatol Arthrosc 2007;15:811-816. Barber FA, Click SD. Meniscus repair rehabilitation with concurrent anterior cruciate reconstruction. Arthroscopy 1997;13:433-437. Small NC. Complications in arthroscopic surgery performed by experienced arthroscopists. Arthroscopy 1988;4:215-221. Small NC. Complications in arthroscopic meniscal surgery. Clin Sports Med 1990;9:609-617. Coen MJ, Caborn DN, Urban W, Nyland J, Johnson DL. An anatomic evaluation of T-Fix suture device placement for arthroscopic all-inside meniscal repair. Arthroscopy 1999;15: 275-280. Cohen SB, Boyd L, Miller MD. Vascular risk associated with meniscal repair using RapidLoc versus FasT-Fix: Comparison of two all-inside meniscal devices. J Knee Surg 2007;20: 235-240. Albrecht-Olsen P, Kristensen G, Burgaard P, Joergensen U, Toerholm C. The arrow versus horizontal suture in arthroscopic meniscus repair. A prospective randomized study with arthroscopic evaluation. Knee Surg Sports Traumatol Arthrosc 1999;7:268-273. Koukoulias N, Papastergiou S, Kazakos K, Poulios G, Parisis K. Clinical results of meniscus repair with the meniscus arrow: A 4- to 8-year follow-up study. Knee Surg Sports Traumatol Arthrosc 2007;15:133-137. Calder SJ, Myers PT. Broken arrow: A complication of meniscal repair. Arthroscopy 1999;15:651-652. Seil R, Rupp S, Dienst M, Mueller B, Bonkhoff H, Kohn DM. Chondral lesions after arthroscopic meniscus repair using meniscus arrows. Arthroscopy 2000;16:E17. Sarimo J, Rantanen J, Tarvainen T, Härkönen M, Orava S. Evaluation of the second-generation meniscus arrow in the fixation of bucket-handle tears in the vascular area of the meniscus. A prospective study of 20 patients with a mean follow-up of 26 months. Knee Surg Sports Traumatol Arthrosc 2005;13:614-618. Huang TL, Lin GT, O’Connor S, Chen DY, Barmada R. Healing potential of experimental meniscal tears in the rabbit. Preliminary results. Clin Orthop Relat Res 1991;267:299305. Petersen W, Pufe T, Stärke C, et al. The effect of locally applied vascular endothelial growth factor on meniscus healing: Gross and histological findings. Arch Orthop Trauma Surg 2007;127:235-240. Arnoczky SP, Warren RF, Spivak JM. Meniscal repair using an exogenous fibrin clot. An experimental study in dogs. J Bone Joint Surg Am 1988;70:1209-1217. Henning CE, Lynch MA, Yearout KM, Vequist SW, Stall-
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erich N. Measurement of meniscofemoral contact pressure after repair of bucket-handle tears with biodegradable implants. Arch Orthop Trauma Surg 2005;125:254-260. Johal P, Williams A, Wragg P, Hunt D, Gedroyc W. Tibiofemoral movement in the living knee. A study of weight bearing and non-weight bearing knee kinematics using “interventional” MRI. J Biomech 2005;38:269-276. Gao J, Wei X, Messner K. Healing of the anterior attachment of the rabbit meniscus to bone. Clin Orthop Relat Res 1998; 348:246-258. Tienen TG, Buma P, Scholten JGF, van Kampen A, Veth RPH, Verdonschot N. Displacement of the medial meniscus within the passive motion characteristics of the human knee joint: An RSA study in human cadaver knees. Knee Surg Sports Traumatol Arthrosc 2005;13:287-292. Dowdy PA, Miniaci A, Arnoczky SP, Fowler PJ, Boughner DR. The effect of cast immobilization on meniscal healing. An experimental study in the dog. Am J Sports Med 1995; 23:721-728. Bray RC, Smith JA, Eng MK, Leonard CA, Sutherland CA, Salo PT. Vascular response of the meniscus to injury: Effects of immobilization. J Orthop Res 2001;19:384-390. Barber FA. Accelerated rehabilitation for meniscus repairs. Arthroscopy 1994;10:206-210. Mariani PP, Santori N, Adriani E, Mastantuono M. Accelerated rehabilitation after arthroscopic meniscal repair: A clinical and magnetic resonance imaging evaluation. Arthroscopy 1996;12:680-686. Barrett GR, Treacy SH, Ruff CG. Preliminary results of the T-Fix endoscopic meniscus repair technique in an anterior cruciate ligament reconstruction population. Arthroscopy 1997;13:218-223. Marinescu R, Laptoiu D, Negrusoiu M. Outside-in meniscus suture technique: 5 years’ follow-up. Knee Surg Sports Traumatol Arthrosc 2003;11:167-172. Hürel C, Mertens F, Verdonk R. Biofix resorbable meniscus arrow for meniscal ruptures: Results of a 1-year follow-up. Knee Surg Sports Traumatol Arthrosc 2000;8:46-52. Kotsovolos ES, Hantes ME, Mastrokalos DS, Lorbach O, Paessler HH. Results of all-inside meniscal repair with the FasT-Fix meniscal repair system. Arthroscopy 2006;22:3-9. Venkatachalam S, Godsiff SP, Harding ML. Review of the clinical results of arthroscopic meniscal repair. Knee 2001;8: 129-133. Petsche TS, Selesnick H, Rochman A. Arthroscopic meniscus repair with bioabsorbable arrows. Arthroscopy 2002;18:246253. Haas AL, Schepsis AA, Hornstein J, Edgar CM. Meniscal repair using the FasT-Fix all-inside meniscal repair device. Arthroscopy 2005;21:167-175. Tsai AM, McAllister DR, Chow S, Young CR, Hame SL. Results of meniscal repair using a bioabsorbable screw. Arthroscopy 2004;20:586-590. Barber FA, Johnson DH, Halbrecht JL. Arthroscopic meniscal repair using the BioStinger. Arthroscopy 2005;21:744750. Gill SS, Diduch DR. Outcomes after meniscal repair using the meniscus arrow in knees undergoing concurrent anterior cruciate ligament reconstruction. Arthroscopy 2002;18:569577. Spindler KP, McCarty EC, Warren TA, Devin C, Connor JT. Prospective comparison of arthroscopic medial meniscal repair technique: Inside-out suture versus entirely arthroscopic arrows. Am J Sports Med 2003;31:929-934. Billante MJ, Diduch DR, Lunardini DJ, Treme GP, Miller MD, Hart JM. Meniscal repair using an all-inside, rapidly absorbing, tensionable device. Arthroscopy 2008;24:779-785.
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99. Barber FA, Coons DA, Ruiz-Suarez M. Meniscal repair with the RapidLoc meniscal repair device. Arthroscopy 2006;22:962-966. 100. Ellermann A, Siebold R, Buelow JU, Sobau C. Clinical evaluation of meniscus repair with a bioabsorbable arrow: A 2- to 3-year follow-up study. Knee Surg Sports Traumatol Arthrosc 2002;10:289-293. 101. Quinby JS, Golish SR, Hart JA, Diduch DR. All-inside meniscal repair using a new flexible, tensionable device. Am J Sports Med 2006;34:1281-1286. 102. Barber FA, Coons DA. Midterm results of meniscal repair using the BioStinger meniscal repair device. Arthroscopy 2006;22:400-405. 103. Kurzweil PR, Tifford CD, Ignacio EM. Unsatisfactory clinical results of meniscal repair using the meniscus arrow. Arthroscopy 2005;21:905. 104. Kurosaka M, Yoshiya S, Kuroda R, Matsui N, Yamamoto T, Tanaka J. Repeat tears of repaired menisci after arthro-
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scopic confirmation of healing. J Bone Joint Surg Br 2002;84:34-37. Gifstad T, Grøntvedt T, Drogset JO. Meniscal repair with biofix arrows: Results after 4.7 years’ follow-up. Am J Sports Med 2007;35:71-74. Koukoulias N, Papastergiou S, Kazakos K, Poulios G, Parisis K. Mid-term clinical results of medial meniscus repair with the meniscus arrow in the unstable knee. Knee Surg Sports Traumatol Arthrosc 2007;15:138-143. Lee GP, Diduch DR. Deteriorating outcomes after meniscal repair using the Meniscus Arrow in knees undergoing concurrent anterior cruciate ligament reconstruction: Increased failure rate with long-term follow-up. Am J Sports Med 2005;33:1138-1141. Majewski M, Stoll R, Widmer H, Müller W, Friederich NF. Midterm and long-term results after arthroscopic suture repair of isolated, longitudinal, vertical meniscal tears in stable knees. Am J Sports Med 2006;34:1072-1076.
Meniscal Repair Christian Stärke, M.D., Sebastian Kopf, M.D., Wolf Petersen, M.D., and Roland Becker, M.D.
Abstract: The meniscus plays an important role in preventing osteoarthritis of the knee. Repair of a meniscal lesion should be strongly considered if the tear is peripheral and longitudinal, with concurrent anterior cruciate ligament reconstruction, and in younger patients. The probability of healing is decreased in complex or degenerative tears, central tears, and tears in unstable knees. Age or extension of the tear into the avascular area are not exclusion criteria. Numerous repair techniques are available, and suture repair seems to provide superior biomechanical stability. However, the clinical success rate does not correlate well with the mechanical strength of the repair technique. Biologic factors might be of greater importance to the success of meniscal repair than the surgical technique. Therefore, the decision on the most appropriate repair technique should not rely on biomechanical parameters alone. Contemporary all-inside repair systems have decreased the operating time and the level of surgical skill required. Despite the ease of use, there is a potential for complications because of the close proximity of vessels, nerves, and tendons, of which the surgeon should be aware. There is no clear consensus on postoperative rehabilitation. Weight bearing in extension would most likely not be crucial in typical longitudinal lesions. However, higher degrees of flexion, particularly with weight bearing, give rise to large excursions of the menisci and to shear motions, and should therefore be advised carefully. Long-term studies show a decline in success rates with time. Further studies are needed to clarify the factors relevant to the healing of the menisci. Tissue engineering techniques to enhance the healing in situ are promising but have not yet evolved to a practicable level. Key Words: Age—Growth factors—Healing—Meniscus—Rehabilitation— Repair technique.
C
linical evidence supports the hypothesis that meniscectomy leads to cartilage degeneration in men. Meniscectomy increases the risk of developing osteoarthritis (OA) of the knee significantly after more than 20 years.1 The extent of resection relates to the
From the Departments of Orthopaedic Surgery at Otto-vonGuericke University Magdeburg (C.S.), Magdeburg, Germany, and Pittsburgh University Medical Center (S.K.), Pittsburgh, Pennsylvania, U.S.A.; the Department of Trauma Surgery, Martin Luther Hospital (W.P.), Berlin, Germany; and the Department for Orthopaedic and Trauma Surgery, City Hospital Brandenburg (R.B.), Brandenburg, Germany. The authors report no conflict of interest. Address correspondence and reprint requests to Roland Becker, M.D., Department for Orthopaedic and Trauma Surgery, City Hospital Brandenburg, Hochstrasse 29, 14776 Brandenburg an der Havel, Germany. E-mail: [email protected] © 2009 by the Arthroscopy Association of North America 0749-8063/09/2509-8403$36.00/0 doi:10.1016/j.arthro.2008.12.010
degree of radiologic OA.2 These arguments suggest that meniscal repair should lead to an improved clinical outcome compared with meniscectomy. However, the results found in the literature are equivocal. Some authors have reported fewer radiologic symptoms of OA in patients who had their meniscus repaired compared with patients who underwent meniscectomy.3 Others failed to prove a substantial clinical benefit to repairing a meniscus.4 A number of case series reported high rates of clinical success of meniscal repair, but investigations with a strong study design are rare. The available data indicate that meniscal repair cannot reliably prevent the progression of degenerative changes and clinical symptoms. A potential explanation is that both meniscal lesions and cartilage damage occur as different features of the same entity, which is not cured by repairing the meniscus. Indeed, there is evidence that meniscal pathology occurs not
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only as a cause but also as a symptom of OA of the knee.5 It seems possible that the fate of a repaired meniscal lesion depends largely on its nature: namely, whether it is degenerative or traumatic in origin. Nonetheless, meniscectomy is an irreversible procedure. Neither replacement nor regeneration of the meniscus have yet evolved to a satisfactory level. It is therefore reasonable to prefer repairing the meniscus to removing it. BLOOD SUPPLY AND TEAR LOCATION In adults, only the peripheral 10% to 25% of the meniscus is vascularized (Fig 1).6 In normal tissue repair, local bleeding provides cellular elements and biochemical mediators that are essential for the repair response. It is therefore generally believed that it is the missing vascular supply that limits the healing capability of the central zones. However, it was shown in animal explant culture models that meniscal tissue is capable of a repair response in the absence of vascularity.7 In a clinical study of 198 meniscal repairs that extended into the avascular zone, 80% remained asymptomatic at follow-up.8 Kalliakmanis et al.9 did not find a significant difference between tears located in the red–red zone and tears in the red–white zone.9 Cannon and Vittori10 found a substantial drop in the healing rates if the rim width exceeded 4 mm in stable knees. Tears located mainly in the central zone have an inferior healing capability.11 So far, it has not been established if the locally different healing response is solely a matter of the vascular supply. Mechanical stress, for instance, may influence the behavior of cells populating the meniscus. The chance of healing is increased if the tear
FIGURE 1. Blood supply of an adult’s meniscus. Note that only the peripheral 10% to 25% of the meniscus is vascularized from the perimeniscal plexus.
FIGURE 2. Menisci with circumferential and radial Cooper zones. Zones 0 and 1 are considered peripheral and are associated with a better healing capability.
either is located in the vascularized area or if access to blood elements is created. Therefore, most surgeons limit repair to lesions located in the Cooper zones12 1 and 2 (Fig 2). Nevertheless, an extension of the tear into the avascular area is not an exclusion criterion. In select patients, such as young athletes, the chance of healing probably outweighs the potential risks of the procedure.13 Tear Pattern and Shape Meniscal lesions are generally more common in males.14 Metcalf and Barrett15 investigated tear patterns in a large number of patients with stable knees; 39% were peripheral tears (Cooper zone 1 or 2). The majority of tears occurred in the posterior horns, with 73% being isolated medial tears and 19% isolated lateral tears. Horizontal tears were most common in this study, followed by complex and flap tears. Longitudinal and bucket-handle tears were found in 19% of cases. In a similar study that investigated patients with an anterior cruciate ligament (ACL) rupture, the portion of lateral meniscal tears increased to 50% in acute cases.16Again, most tears were located in the posterior horns. Peripheral tears (Cooper zones 1 and 2) were found in more than 60% of cases. The probability of encountering tears suitable for repair is substantially decreased in stable knees compared with ligament injured knees. If repaired, double longitudinal or complex tears have a higher probability for failure.8 Tears that involve only the posterior segment seem to have an inferior healing rate compared with lesions extending into the middle segments.17
MENISCAL REPAIR Horizontal cleavage tears are a frequent finding and may exist without clinical symptoms.18 There is little information on the significance of this type of tear. They can give rise to flap tears but are otherwise mechanically stable. It has not been clarified yet whether patients benefit from the repair of these tears. It appears questionable if sutures could neutralize the shear motion that is thought to be responsible for the development of these tears. If horizontal tears are encountered incidentally— during ACL surgery, for example—they might be left alone. At times, those tears are accompanied by meniscal cysts,19 which are thought to arise from the influx of joint fluid through meniscal tears. Partial meniscectomy is often carried out to drain the cyst. It has been suggested that aspiration of the cyst and closure of the tear with sutures could avoid the need for a meniscectomy.20 Controversy exists concerning radial tears. They should be clearly distinguished between complete and partial radial tears. Empirically, partial radial tears often affect the central parts while the outer rim remains intact. This has important mechanical implications: in partial radial tears, the important circumferential fiber bundles are mostly intact and the function of the meniscus is retained. Further, those tears largely extend into the avascular area, which limits the chance of healing.21 Therefore, particularly in small radial tears, debridement of loose edges is usually sufficient. In cases of a complete trans-section, however, the effect can be similar to a complete meniscectomy.22 If left untreated, weight bearing would extrude the meniscus out of the joint space and most likely no functionally sufficient healing would occur. Although it has been found that lateral meniscal tears in conjunction with ACL tears seem to have good prognosis in general,23 some surgeons24 including the authors of this review, feel that it might be beneficial to approximate and secure the tear margins of a complete tear with sutures. In those cases, non–weight bearing exercise is warranted postoperatively because circumferential stress (so-called “hoop stress”) is induced in the meniscus with tibiofemoral loads, which would distract the tear margins. The influence of the tear length on the failure rate is not entirely clear. Although some authors could not prove an association between the failure rate and the length of the tear,11 others found that failures occurred significantly earlier in larger tears.25 In one study, the healing rate was in excess of 90% if the length of the tear was less than 2 cm, whereas it was only 50% with tears larger than 4 cm.10
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Medial Versus Lateral Lesions In a series of 53 patients, no significant difference in the healing rate was found by means of computed tomographic arthrography for the medial and lateral meniscus.17 Cannon and Vittori10 found lateral menisci to have a better healing rate than medial menisci. Another investigation into ACL-reconstructed knees did not find different failure rates for lesions located in the Cooper zones 1 and 2 of either the medial or lateral meniscus.26 It is not entirely clear whether or not the healing potential in the medial and lateral meniscus are different. Yet the potential sequelae of meniscectomy are more serious in the lateral meniscus than in the medial.2 Therefore, in the decision-making process, it matters which of the menisci is affected. Influence of Age It has been observed that meniscal tissue from patients over 40 years of age has a lesser cellularity and a decreased healing response than tissue from younger patients.27 Eggli et al.28 stratified their patients into groups older and younger than 30 years and found retears to be more frequent in older patients. Bach et al.25 analyzed failures in a series of 300 meniscal repairs.25 The average time to failure was 34 months in this study. Older patients failed significantly later than patients younger than 30 years of age. Other investigators did not find a correlation between the revision rate and patient age in 113 cases of an allinside repair using the Meniscus Arrow (Conmed Linvatec, Largo, FL).29 In a recent study, the results of meniscal repair in patients with reconstructed ACLs are reported, and in terms of failures, no difference was found between patients older or younger than 35 years of age.9 The rates of clinical success in repair procedures, which involve the avascular area, seem not to be worse in older patients (40 to 58 years) compared with the younger population.8,30 The outcome of repair in young patients is not generally favorable, as one might expect.31 By means of arthrography or magnetic resonance imaging, it was shown that healing of repaired tears remained incomplete in a high fraction of young patients, even in the absence of symptoms.31 The same negative prognostic factors as in older patients, such as a complex tear configuration, large distance to the periphery, or ligamentous instability, apply to the younger patients.32 Obviously, the clinical results in younger patients are in conflict with the better intrinsic healing capability that the basic science suggests. First, there are no randomized controlled studies in which the treatment
C. STA¨RKE ET AL.
1036 TABLE 1.
Overview of Meniscal Repair Instruments and Implants
Suture ●
●
●
Inside-out (generic flexible needles and prebent cannulas) Outside-in (generic intravenous cannulae) All-inside (Meniscal Viper [Arthrex])
Suture Repair Systems
Rigid Implants ●
● ●
●
Meniscus Arrow (Conmed Linvatec) Meniscal Dart (Arthrex) BioStinger (Conmed Linvatec) Meniscal Screw (Biomet)
●
● ● ●
FasT-Fix (Smith & Nephew Endoscopy) MaxFire (Biomet) Meniscal Cinch (Arthrex) RapidLoc (DePuy Mitek)
allocation is primarily based on patient age. Most investigators will consider the macroscopic appearance of the meniscus in their treatment decision and would not repair tears in grossly degenerated menisci. This results in a selection bias, which potentially obscures the influence of the patient’s age. Further, higher demands in sports and occupation in the young population might compromise the outcome despite a better intrinsic healing capability. The available data suggest that age is not a general contraindication to meniscal repair—it merely increases the likelihood of encountering a tear that is not suitable for repair.15
ing time and problems to reach the far posterior regions of the meniscus. Therefore, implants to be used without the need for additional incisions (all-inside) were developed. The first generation of those allinside systems were small rigid implants with barbs or threads, usually made from absorbable polymers. In addition to occasional mechanical complications, most of the solid all-inside implants show a considerable inferior stiffness and failure load, partially less than 10 N.38,39 In an effort to provide the convenience of the rigid implants while giving the strength of suture repair, combinations of sutures and rigid parts were developed (Table 1; Figs 3–5). While the FasTFix (Smith & Nephew Endoscopy, Andover, MA) implant was the first of its kind, all major suppliers of arthroscopic equipment now offer devices with a similar design. Table 2 shows the rates of clinical success for a variety of repair techniques and implants. It should be noted that partial healing or failure of heal-
CHOICE OF THE REPAIR TECHNIQUE A central question for the surgeon is whether the healing response and long-term outcome depends on the technique that is used. Horizontal sutures usually yield a lower failure load because they lie in between the circumferential fiber bundles and are pulled through those as they are loaded.33 Vertical sutures are commonly considered the gold standard in regard to the strength, which was found to be in a range from about 60 N to more than 200 N, depending on the investigated model.34,35 In the case of vertical sutures, failure occurs mainly by rupture of the suture because the strong circumferential fiber bundles of the meniscus are contained within the suture loop. Here, the choice of the suture material determines the failure load.36 In general, vertical sutures are preferred to horizontal stitches; the techniques are very similar, but vertical sutures result in stiffer repairs. Variations, with the limbs of the suture crossing each other, further increase the failure load.37 Conventional suture techniques are afflicted with a relatively long operat-
FIGURE 3. Bioresorbable implants. (A) Meniscus Arrow (Conmed Linvatec). (B) Meniscal Dart (Arthrex). (C) BioStinger (Conmed Linvatec).
MENISCAL REPAIR
1037
lesions.40,41 Shear forces might be more relevant but are not addressed in most studies investigating the stability of repair systems. The success rates for the Meniscus Arrow and conventional sutures seem to drop with time (Table 2). Because there are no long-term studies for the newer implants, the false impression might arise that those are more successful than sutures or the Arrow. It is possible that the same decline in the healing rate will take effect with a longer follow-up of those systems. COMPLICATIONS AND PITFALLS OF MENISCAL REPAIR Bleeding or pseudoaneurysms descending from popliteal vessels are described with arthroscopic meniscal surgery. But those reports almost exclusively pertain to the resection of the posterior horns,42,43 not meniscal repair. In a cadaver study, it was found that the lateral genicular artery is at risk of being penetrated by the needle with inside-out and outside-in sutures of the lateral meniscus (Fig 6). However, it has not yet been established whether a laceration of this vessel has detrimental effects on the healing meniscus. Capture of branches of the peroneal nerve is possible when lateral meniscal lesions are sutured, but seems to be rather seldom. Proper use of retractors can largely avoid this complication.44 In the case of medial meniscal repair, the saphenous vein and nerve are at risk of being affected.45 Although transient neuro-
FIGURE 4. All-inside suture repair systems. (A) FasT-Fix (Smith & Nephew Endoscopy). (B) MaxFire (Biomet). (C) Meniscal Cinch (Arthrex). (D) RapidLoc (DePuy Mitek).
ing does not necessarily cause clinical symptoms.8 Therefore, rates of so-called clinical healing do not exactly reflect the healing status in a structural sense. Further, the clinical success rates do not correspond closely to the magnitudes of the mechanical strength that is found for the different repair techniques38 (Table 2). The available data do not support the assumption that stronger repair techniques are accompanied by better outcomes. It must be acknowledged that mechanical testing is usually done in the axis of insertion, although it has not been shown conclusively that substantial distraction forces do occur on repaired
FIGURE 5. Instruments for suture repair. (A) Meniscal Viper (Arthrex). (B) Prebent cannula, nitinol needle (Arthrex).
C. STA¨RKE ET AL.
1038 TABLE 2. Author Albrecht-Olsen et al.51 Pujol et al.17 Cannon and Vittori10 Kocabey et al.77 Barrett et al.87 Marinescu et al.88 Hürel et al.89 Kotsovolos et al.90 Frosch et al.76 Venkatachalam et al.91 Petsche et al.92 Haas et al.93 Tsai et al.94 Kalliakmanis et al.9 Barber et al.95 Gill and Diduch96 Spindler et al.97 Billante et al.98 Barber et al.99 Ellermann et al.100 Noyes and Barber-Westin30 Quinby et al.101 Barber and Coons102 Rubman et al.8 Kurzweil et al.103 Kurosaka et al.104 Gifstad et al.105 Koukoulias et al.106 Lee and Diduch107 Eggli et al.28 Majewski et al.108
Summary of Outcomes for Different Repair Techniques and Systems
No. of Follow-up Concurrent Effect of Meniscal Cases Time (mo) ACLR ACLR Arrow Screw T-Fix FasT-Fix RapidLoc BioStinger Suture 65 50 90 55 21 68 26 61 40 62 29 42 26 265 89 32 125 38 32 105
3 6 7-10 10.3 12 12 16.7 18 18 21 24 24.3 24.5 24.5 26.5 27 68/27 30.4 31 33
Some Majority Majority Majority All Some Some Majority Majority Some Majority Majority Some All Majority All All All Majority Majority
— None Better — — — — None Better Better — Better — — — — — — None None
91 — — — — — 88 — — 56 93 — — — — 90.6 89 — — 80
— — — — — — — — 100 (82) — — — 78 — — — — — — —
— — — 96 81 — — — — 57 — — — 89.4 — — — — — —
— 82 — — — — — 90.2 — — — 86 — 92.4 — — — — — —
— — — — — — — — — — — — — 86.3 — — — 86.8 87.5 —
— — — — — — — — — — — — — — 91 — — — — —
75 — 93 (50) — — 94 — — — 78 — — — — 100 — 88 — — —
30 54 41 198 60 114 118 11 28 52 116
34 34.8 36.8 42 54 13/54 56.4 73 79.2 90 120
Majority All Majority Majority Majority Majority Some None All None None
Better — — — Better — None — — — —
— — — — 72 — 59 72.7 71.4 — —
— — — — — — — — — — —
— — — — — — — — — — —
— — — — — — — — — — —
— 90.7 — — — — — — — — —
— — 95 — — — — — — — —
87 — — — — 68 — — — 73 76
NOTE. The criteria for success are heterogenous. Most authors shown in Table 2 define failure as the need for repeat arthroscopy or symptoms of locking and catching. Table 2 is sorted by length of follow-up time, from the shortest amount of time at the top to the longest amount of time at the bottom. Whether or not the anterior cruciate ligament was reconstructed is given and, if applicable, the impact on the outcome. Numbers in parentheses give the outcome for the subgroup with unstable knees. It should be noted that there is a general trend of increasing failure rates with time. Meniscal repairs in anterior cruciate ligament–reconstructed knees have better results than repairs in primary stable knees or unstable knees. Abbreviation: ACLR, anterior cruciate ligament reconstruction.
praxia was described in up to 22% of cases,46 permanent damage was found to occur in 0.4% to 1%.47,48 An anatomic study that investigated the placement of the T-Fix (Smith & Nephew Endoscopy) device showed that neurovascular structures seem not to be at risk of being pierced with the insertion cannula.49 In a more recent investigation, the authors found that the application cannula of a FasT-Fix device came within 3 mm of the popliteal artery under certain circumstances, whereas the RapidLoc (DePuy Mitek, Raynham, MA), with its shorter cannula, had a greater distance to that vessel.50 The use of the depth limiter that comes with the FasT-Fix is therefore recom-
mended. However, Kalliakmanis et al.9 reported no neurovascular complications in a larger series of repairs using the T-Fix and FasT-Fix implants. In the case of solid implants, the depth of penetration can usually be controlled by choosing an implant of appropriate length. Nevertheless, cases of nerve damage have been described.51,52 A complication that is less dramatic than neurovascular damage and may thus be under-recognized is accidental soft tissue tenodeses. Anatomic studies have shown, for example, that the sartorius tendon, the deep medial collateral ligament, and the popliteus tendon are at risk of being penetrated by the application cannula (Fig 7).45,49 Al-
MENISCAL REPAIR
FIGURE 6. Coronal magnetic resonance imaging slice illustrating the close anatomic relationship of the inferior lateral genicular artery (ILGA) and the lateral meniscus. The vessel is at risk when passing needles/sutures inside-out or outside-in. (LCL, lateral collateral ligament)
1039
seem to improve the healing in animal models58 and in humans.59 It is postulated that the clot serves as a chemotactic and mitogenous stimulus. Some investigators succeeded in enhancing the healing of meniscal lesions with the application of mesenchymal stem cells.60 It is not clear whether this is a direct action of the progenitor cells or is rather mediated by secretion of certain stimulating factors. The behavior of meniscal fibrochondrocytes can be modulated when the cells are exposed to certain growth factors.61 The response to mitogenic stimuli, however, seems not to be necessarily the same for all regions.62 Human menisci are populated by cells of different phenotypes that might respond differently to extrinsic stimuli, as was reported by Verdonk et al.63 There are study findings showing that trephination or rasping alone without suturing the meniscus might be a reasonable option in stable tears. Shelbourne and Heinrich23 and Shelbourne and Rask64 published clinical studies investigating the fate of stable lesions in the medial and lateral meniscus that were either left alone or treated by rasping and trephination in conjunction with an ACL reconstruction. They found that only a minor proportion of their patients required subsequent surgery for their meniscus. Fox et al.65 reported on a similar procedure with good or excellent
though the results are not as severe as lacerations of the nerves or vessels, increased postoperative pain may compromise and slow down rehabilitation. Complications specific to solid repair devices are migration or breakage of the implant.53 Parts of the implants that surmount the surface of the meniscus can also wear down the cartilage in the contact zones and cause chronic synovitis.54 Although this has been addressed by changes in the design and resorption time of the implants, it seems that these problems are not fully eliminated.55 ENHANCEMENT OF THE HEALING RESPONSE Biologic factors might be of greater importance to the success of meniscal repair than the choice of the surgical technique. The healing potential apparently coincides with the vascular supply of the meniscal tissue.56 However, the local application of vascular endothelial growth factor did not lead to improved healing in a sheep model.57 Exogenous fibrin clots
FIGURE 7. Transverse magnetic resonance imaging slice of a knee at the height of the tibiofemoral joint space. Structures potentially at risk of being penetrated by a cannula or being caught by a suture are shown. (LCL, lateral collateral ligament; MCL, medial collateral ligament)
1040
C. STA¨RKE ET AL.
results in about 90% of cases. Zhang and Arnold66 and Zhang et al.67 have shown in animal studies that trephination enhances the healing capacity of lesions in the avascular zone with and without additional sutures. INFLUENCE OF CONCURRENT INJURIES An injury to the ACL is the most often described entity encountered together with a meniscus tear. While the classic description of the O’Donoghue triad comprises a lesion of the medial meniscus together with a rupture of the ACL and medial collateral ligament, Barber68 and Shelbourne and Nitz69 have pointed out that lesions of the lateral meniscus are much more common in acute injuries. In chronic ACL deficiency, the relation shifts toward the medial meniscus.16,70 It has been shown that an abnormal anteroposterior laxity increases the resultant forces in the medial meniscus.71 The meniscus becomes a secondary stabilizer, a purpose for which it is not primarily made. Accumulated microdamage explains the increasing rates of medial meniscal lesions in the course of untreated ACL deficiency. Conclusively, meniscal repair should result in a better outcome if it is done in conjunction with a stabilization of the knee. There have been no randomized studies that have investigated the outcome of meniscal repair in relation to the ACL state. Usually, the anteroposterior instability will be regarded as the primary problem, and randomization in terms of the ACL reconstruction is not an option. Nevertheless, there are some studies that comprise subgroups of patients with either ligamentous intact, reconstructed, or unstable knees. In the majority of these studies, it seems that the outcome of a repair is better with concomitant reconstruction than in knees that remain unstable72-74 or even better than knees without ACL injury.75-77 The fact that meniscal repair appears to be more successful in combination with an ACL reconstruction deserves some detailed reflection. The simplest explanation is that, with the stabilization of the knee, the inciting cause for the repeated microtrauma of the menisci is eliminated, or at least diminished. Moreover, marrow elements are introduced into the joint cavity with the ACL procedure that, as described earlier, are thought to modulate the healing response of meniscal fibrochondrocytes. Another potential explanation for a seemingly improved healing rate with concurrent ACL surgery is related to patient selection. It must be assumed that in the subgroup of patients
with concomitant ACL reconstruction, the main reason for the procedure is instability, and that conclusively not only symptomatic but also clinically silent lesions of the meniscus are identified and repaired. However, in patients with stable knees, the cause for the meniscal repair usually is meniscal symptoms, such as locking or effusion. The possibility of a selection bias must therefore be considered. REHABILITATION Patients should be informed in advance that meniscal repair is usually accompanied by much longer periods of restricted motion and limitation of the knee function than after a meniscectomy. It has been shown that the reparability of meniscal tears can be predicted reasonably well by magnetic resonance imaging studies,78 which gives both the patient and surgeon the opportunity to be prepared in advance. A generally valid rehabilitation algorithm has not been established. Rehabilitation plans need to be individually tailored and should take into consideration the nature of the tear, concurrent injuries and procedures, and the influence of specific exercises on the repaired tear (Table 3). There are both mechanical and biologic effects associated with postoperative weight bearing and motion of the knee. In repaired bucket-handle lesions, weight bearing reduces the meniscus and stabilizes the tear.40 Flexion under tibiofemoral loads of the knee, however, leads to increasing compressive and shear loads in the posterior horn. It was reported that weight bearing flexion from full extension to 90° increases the pressure on the posterior horn by, roughly, a factor of 4.79 The menisci translate dorsally with knee flexion. This motion depends not only on the flexion angle but also on the weight bearing condition.80 The magTABLE 3.
Postoperative Rehabilitation Program for a Typical Bucket-Handle Lesion
Early Phase ● ● ● ● ●
Ice and analgesics Crutches as needed Brace to limit motion Partial or full weight bearing Non–weight bearing motion (60° to 90°)
Intermediate Phase
Late Phase ● ●
● ● ● ●
Aqua jogging Isometric strength training Continue brace No squats for 12⫹ wks
●
Regain full range of motion Strength training Consider modification of activities if related to development of tear
NOTE. Patients might need an individually tailored program.
MENISCAL REPAIR nitude of the posterior femoral rollback, and necessarily the posteriorly directed translation of the menisci, is substantially increased in the weight-loaded knee compared with the unloaded state. Although this was not directly proven by the cited study, motion exercises of the knee without weight bearing might therefore be preferable during rehabilitation to limit the stress on the repair. Weight bearing in extension most likely does not pose a problem to repaired meniscal lesions. An exception to this is complete transections of circumferential fiber bundles of the meniscus, such as radial tears that comprise the whole cross-section or posterior root tears. In those cases, weight bearing would be deleterious because the hoop stress distracts the tear margins and healing is prevented.81 Tibial rotation causes large excursions of the meniscus within the first 30° of flexion.82 Terminal flexion is accompanied by a large dorsal translation of the condyles and causes increased compressive stress of the meniscus.79,80 Therefore, deep squats and tibial rotation should be avoided for at least 12 weeks. Although the magnitude of the posterior translation of the medial and lateral meniscus is different, no significant difference in the pressure that arises on the medial and lateral posterior horns was found by Becker et al.79 at up to 90° of flexion. So far, it is not clear if medial and lateral meniscal repairs deserve different rehabilitation protocols. Most investigations about the biologic effects of immobilization found that it impaired the healing of repaired menisci.83 Limited motion and weight bearing in full extension might have stimulating effects on the healing response.84 There have been some clinical investigations regarding the effect of a more aggressive rehabilitation of meniscal repair patients. Barber and Click46 and Barber85 did not find any evidence that an accelerated program compromises the result of the repair. Similarly, Mariani et al.86 failed to show deleterious effects when patients with concomitant ACL surgery were subjected to an accelerated rehabilitation program. However, the design and case number of those studies do not allow one to infer in general that restrictions after meniscal repair are not necessary. CONCLUSIONS Meniscal preservation has gained a high level of awareness in the recent years. The surgeon must consider the nature of the tear in his decision of whether or not to repair or resect. The prognosis of a meniscal repair is better if it is possible to identify and treat an underlying problem like an ACL deficiency. Contem-
1041
porary all-inside repair systems have significantly decreased the level of technical skills required for a successful repair. There is currently no scientifically substantiated reason to believe that the choice of a particular repair technique would improve the outcome. It has not been shown thus far that a high failure load is associated with better clinical results.
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40. 41. 42. 43. 44.
45.
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51.
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53. 54. 55.
56.
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