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Meniscus preservation; rationale, repair techniques and results
The Knee 10 (2003) 1–11
Review
Meniscus preservation; rationale, repair techniques and results夞 Kevin T. Boyd, Peter T. Myers* Brisbane Orthopaedic and Sports Medicine Centre, Holy Spirit Hospital, 259 Wickham Terrace, Brisbane 4000, Australia Received 21 October 2002; received in revised form 15 November 2002; accepted 24 November 2002
Abstract It is inescapable that loss of part or all of the structure of the meniscus of the knee alters the biomechanics of knee function leading to a gradual deterioration of the chondral surface, which ultimately will result in osteoarthritis. The goal of the knee surgeon should therefore be to preserve as much as possible the function of the meniscus. Classic teaching is that many meniscal tears, which are peripheral and longtitudinal, will heal if sutured and protected during a slow healing process. However it is clear that other tear configurations can heal if given the opportunity by adequate preparation of the meniscus rim, careful suturing and delayed rehabilitation. Thus some radial tears, horn avulsions, double longtitudinal tears and retears, previously thought to be irreparable, can be sutured with good results. Over 12 years, 288 meniscus repairs were undertaken in 265 patients ranging in age from 12 to 70 years. Most were repaired at the time of anterior cruciate ligament reconstruction, although 55 were isolated repairs. While the average time from injury to surgery was 11.7 months (1 – 72), one third of patient’s already had chondral damage of at least Outerbridge Grade 2. The purpose of this paper is to report on the more difficult meniscus repair techniques and as such formal follow up was not undertaken to determine the final outcome of these patients. Never the less it is estimated from known data that there was a retear rate in the order of less than 10%. There have been three complications, 2 infections and one temporary neuropraxia of the common peroneal nerve; all of these healed completely with appropriate treatment. Therefore we recommend that meniscus repair should be undertaken if a clinical case for meniscal preservation exists, even if the appearances are not those classically recommended. 䊚 2002 Elsevier Science B.V. All rights reserved. Keywords: Meniscus; Menisectomy; Arthroscopy; Meniscus repair
1. Introduction Meniscal tears are a common and important source of knee dysfunction, particularly in younger, active individuals who place significant demand on their knees. The menisci are now recognised to be integral parts of the biomechanical function of the knee and not the vestigial and dispensable remains of evolution as once thought. Although Fairbank, in 1948, clearly demonstrated the radiological consequences for the knee of total menisectomy w1x, this remained the widespread treatment of meniscal tears until the 1970s. 夞 This review article is based on a presentation given at the COKS meeting in Cape Town during March 2002. *Corresponding author. E-mail address: [email protected] (P.T. Myers).
Over the last two decades, with the general adoption of arthroscopy, there has been an improvement in surgical techniques to assess and treat meniscal pathology. These improvements along with an enhanced understanding of the biomechanical properties of the menisci have led to a shift towards preservation of the menisci w2–4x. Meniscal preservation includes leaving small or partial tears, partial menisectomy and meniscus repair techniques. Partial menisectomy, where only the damaged, unstable portion of the meniscus is removed leaving the remainder intact has become almost the routine treatment for damaged menisci. Nevertheless, partial menisectomy has also been shown to be associated with an increased incidence of degenerative changes w5 x . In an attempt to maintain as near normal a knee as possible, techniques for meniscal repair and adjuncts to
0968-0160/03/$ - see front matter 䊚 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 6 8 - 0 1 6 0 Ž 0 2 . 0 0 1 4 7 - 3
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Fig. 1. A compressive force (white arrow) is converted by the shape of the meniscus to a radially directed force (black arrows), which is taken up as a tension force (dashed arrow) within the meniscus.
promote meniscal healing have been developed. Meniscal fragments, which otherwise would have been excised, can now be retained. These techniques can be demanding and the criteria for repair continue to be defined. This paper is a personal review of the rationale for meniscal preservation and introduces the techniques and experience of the senior author (P.T.M.). 2. Meniscal biomechanics The main function of the menisci is one of load transmission. The majority of the collagen fibres are large and coarse and are arranged in a circumferential manner. These fibres are stabilised with radially running fibres acting as ties. This structure suggests the ability to bear load is by containment of the so-called ‘hoop stresses’ w6x (Fig. 1). It has been determined that approximately 50% of the body’s weight is transmitted through the menisci in extension and up to 85% in 908 of flexion w7x. The menisci, however, are mobile structures that move ante-
Fig. 2. With ACL deficiency an anteriorly directed force (white arrow) is partly resisted by an intact medial meniscus (black arrow). If the meniscus is also deficient then the tibia can move further anteriorly (adapted from Ref. w10x).
riorly and posteriorly to allow maintenance of congruency throughout the range of flexion. The radius of curvature also changes to accommodate the reduced radius of the femoral condyles as flexion and rollback occurs w8x. The medial meniscus is more restrained than the lateral meniscus, particularly in the postero-medial corner, and this may explain why tears of this area are more common. It is now well accepted that loss of all or part of a meniscus increases point loading and results in premature wear of the knee due to altered mechanical forces. The rate at which arthrosis develops, however, depends on a number of factors and these may be regarded as knee factors and patient factors. The volume of meniscus lost has been considered. Total menisectomy has been estimated to reduce the joint surface contact area by 75%, increasing local peak contact pressure by 235%. Partial menisectomy also reduces contact area by 10% and increases point pressures by 65% w9x. The nature of the tear is important. Radial tears extending to the periphery may not result in much volume loss but may completely defunction the meniscus through an inability to resist hoop stresses. Associated injuries either at the time of meniscal tear or subsequently, such as chondral damage and anterior cruciate ligament rupture, will also have a significant effect on the knee’s long-term prognosis. Patient factors include limb alignment, age at time of injury, activity level, weight and inherent genetic constitution. The menisci also act as secondary stability restraints in the knee. The effect in a stable knee remains controversial but in an ACL deficient knee there is no doubt that loss of a meniscus increases measurable joint laxity. In these situations, it is suggested that the intact posterior horn of the medial meniscus acts as a wedge or ‘stop’ to anterior translation of the tibia w10x (Fig. 2). Unfortunately, it is not uncommon to witness an ACL deficient knee in an active individual sequentially undergoing medial and lateral menisectomies with a rapid progression to premature arthrosis. Further biomechanical functions of the menisci have been postulated. These include shock absorption, lubrication, joint nutrition and proprioception w11x. The menisci exhibit viscoelastic properties, which may serve to attenuate impacts sustained through the knee on loading. The improved congruity that they provide has been suggested to aid joint lubrication and cartilage nutrition by promoting fluid shifts in and out of the cartilage surface layers. Recent studies have shown the presence of mechano-receptors and free nerve endings in the peripheral, two thirds of the meniscus body and the horns, particularly the posterior horns w12x. This suggests an important role of the menisci in proprioceptive feedback, the initiation of protective reflexes and joint pain. This may also explain why meniscal tears without a significant mechanical component can still be a source of painful symptoms.
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3. Meniscal healing The capacity of meniscus to heal is limited, particularly the central portions, which are largely avascular, aneural and alymphatic. However, in 1936, King showed that meniscal healing in dogs could occur providing there was communication with the peripheral blood supply w13x. As with other soft and bony tissues, there is a need for a balance between blood supply, and hence associated cellular and tissue repair factors, and component stability to permit healing. The process would appear to be along the same lines as healing in other soft tissues and, in the vascular portion of the meniscus, it would appear that healing is largely complete by 10 weeks w14x, although maturation of the scar may continue for many months. As indications for meniscal repair are extended, attempts to promote an environment more conducive to healing have been introduced. The vascular anatomy of the human meniscus has been well described by Arnoczky and Warren w15x. The blood supply is by way of the superior and inferior medial and lateral geniculate arteries. The outer rim of the meniscus is vascularized up to 30% of its width on the medial side and 25% on the lateral side. In addition, there is a synovial fringe that extends some 3 mm over the surface of each meniscus adding further to the peripheral vascularity. The concept of ‘red-on-red’, red-on-white’ and ‘whiteon-white’ tears, describing the vascular status of each tear location, is a useful classification. ‘Red-on-red’ tears are perhaps a misnomer as all tears must be ‘redon-white’, as the central portion, by its nature, must have had its vascular supply disrupted. Nevertheless, it is a reflexion of the peripheral location and is a good indicator that healing should occur. ‘White-on-white’ tears are located within the avascular zone and hence have the least potential to heal. The majority of reports on meniscal repair address primarily longitudinal tears, which are indeed the commonest tear to be repaired. Current practice suggests that certain tears are incapable of healing although anecdotally this has not been our experience. As with any scarred tissue, it is likely, however, that even fully healed menisci will not regain normal biomechanical strength. Indeed, there is some evidence at 12 weeks after meniscal suture, meniscal strength may be significantly reduced at only 26% of the normal side w16x. 4. Nature of tears Meniscal tears are most commonly described on the basis of their anatomical location and appearance. They may also be partial- or full-thickness. Partial thickness tears can generally be left alone to heal by themselves. Despite the recent advances in MRI scanning, arthroscopic assessment remains the definitive technique of
Fig. 3. Repair of a displaced medial bucket handle tear.
tear identification. However, other features such as whether the torn fragment has itself been damaged will influence the decision to repair or resect. In the past, we have perhaps been too hasty to excise a meniscus just because it is torn without due consideration as to whether it was, in fact, the cause of the symptoms and whether it might heal if left well alone. The types of meniscal tears are discussed as follows. 4.1. Vertical (longitudinalycircumferential) tears This is the more common type to be repaired. The classical configuration of a meniscus tear suitable for repair is a full-thickness, vertical tear extending less than 2 cm with no associated damage and within 2 mm of the periphery. In addition, it is recommended that the tear be relatively fresh, be in a young patient and the knee otherwise stable w11x. It would be fair to say that ‘best practice’ would be to always repair a meniscus tear of this description, as the likelihood of healing is approximately 85%. However, these are not the only tears that can heal given satisfactory stability and biology. The unstable, longitudinal tear, the ‘bucket handle’ tear, can also be addressed. Due to their extensive nature, excision of these may well result in subtotal menisectomy and should be avoided if the displaced fragment is of sufficiently good quality (Fig. 3). A double bucket handle tear can be seen in the ACL deficient knee
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Fig. 4. Repair of a double bucket handle tear of the medial meniscus showing abrasion of the rim (1), the peripheral or ‘2nd handle’ fragment (2), a suture being placed (3) and the finished 8-suture repair.
following repeated injuries during episodes of giving way. These too can be repaired and go onto heal, although the more peripheral ‘bucket handle’ portion may need to be excised (Fig. 4). 4.2. Radial tears Radial tears of the lateral meniscus are commonly seen following ACL disruption. If small, these can be simply saucerized. Radial tears that extend to the periphery are significant injuries as they disrupt the ability of the meniscus to contain hoop stresses (Fig. 1). Traditionally, it has been felt inappropriate to repair these. Nevertheless, we, along with others have seen tears of this nature heal with meniscal repair w17x (Fig. 5). 4.3. Horizontal (cleavageytransverse) tears These tears are difficult to manage and, in our experience, are not suitable for repair. Typically, they develop in the early degenerate meniscus due to differential shear stresses between superior and inferior leaves of the meniscus. They may be associated with meniscal cyst formation if there is a communication to the
Fig. 5. A posterior horn radial tear is repaired by using 2 or 3 horizontal sutures.
periphery. We recommend excision of the inferior leaf of the meniscus, attempting to leave the superior leaf intact. The pre-horizontal tear (a contained split within the meniscus but before rupture into the joint has occurred) is a particularly difficult management problem (Fig. 6). Here the patient has localising symptoms and an abnormal meniscus signal (grade 2) on MRI. Yet there is no apparent tear at arthroscopy and no other source of pathology can be identified. Following appropriate discussion with the patient, we have opened such menisci and found an established horizontal split within the meniscus substance. Treatment along the lines outlined above has relieved symptoms. 4.4. Degenerate tears These tears may be of a variety of configurations and can be a source of new or increased symptoms in an arthritic knee. Meniscal degeneration is evident bio-
Fig. 6. A transverse degeneration of the posterior horn of the medial meniscus is shown with out connection to the articular surface.
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chemically in the fourth decade of life. Usually, the meniscus is of poor quality and is typically excised back to a stable rim. Unfortunately for the patient, although they may be relieved of symptoms pertaining to the tear, overzealous excision of the degenerate body of the meniscus may expose worn joint surfaces with a continuation, or worsening, of painful symptoms. Fortunately, these tend to occur in the ageing population where alternative treatment options exist for end-stage arthrosis and continuing disabling symptoms. 4.5. Complex tears These are tears in two or more planes within a meniscus. It is generally recommended that these are excised and yet recent experience is challenging the fact that these tears are unrepairable. If the clinical situation strongly suggests the patient will benefit from meniscal preservation then repair of these tears can be performed attending to basic principles. The oblique or parrot beak tear represents a type of complex tear. These can have a wide variety of configurations and like radial tears can have significant consequences for knee biomechanics if they extend to the periphery. 4.6. Horn detachments These are included, as even though the meniscus substance may be intact the biomechanical qualities will be significantly affected. Usually, the posterior horns are affected. In these circumstances, we recommend reattachment of the posterior horn as described below. 5. Treatment options Accurate arthroscopic visualisation is important to define the extent and nature of the tear. Only when this has been adequately assessed, can an informed decision about treatment be made. Both the upper and lower surfaces of each meniscus can usually be fully assessed with the use of an arthroscopic hook or probe. 5.1. Leave alone Partial thickness tears or full-thickness tears (-8 mm) are rarely a cause of mechanical symptoms and there is a good likelihood of spontaneous healing particularly after a recent injury. This may be promoted by adjuncts to healing such as local synovial abrasion. The simple presence of a meniscal tear does not always mean that a partial menisectomy must be performed! 5.2. Excision It is not so long ago that the traditional orthopaedic management of a suspected meniscal tear was open total
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menisectomy. Fortunately, for the patient, this type of treatment is now confined to the history books. Arthroscopic partial menisectomy is the most common treatment undertaken and is normally effective in eliminating mechanical and irritative symptoms associated with a damaged meniscus. This may also be beneficial by reducing the incidence of articular surface damage through recurrent chaffing and catching of a meniscal fragment between joint surfaces. Nevertheless, the biomechanical properties of the knee’s ability to withstand loads will be affected by partial menisectomy. We feel it is important to advise patients of this and recommend that they maintain good endurance and tone in their quadriceps musculature and be conscious of the degree of impact loading that they subsequently undertake. 5.3. Repair Annandale is credited with the first meniscal repair in 1885 w18x. A more aggressive approach to meniscal preservation, particularly in knees undergoing ACL reconstruction, is becoming more commonplace. The immediate goals are to maintain the ability of the meniscus to transmit load and provide stability. In the longer-term this may prevent or, at least, reduce the risk of progression to premature osteoarthrosis. Maintenance of an intact functioning meniscus is felt to be one of the major factors in reducing the risk of progression to radiographic changes of arthritis w19,20x. The ability to pre-operatively identify patients suitable for meniscal repair would be ideal. This would aid the process of informed consent and the planning of theatre time. At present, however, the decision to repair or cannot made until the time of arthroscopy. The role of the meniscus in protecting the joint surfaces should be emphasised. The presence of valgusyvarus tendencies or evidence of established articular surface damage at arthroscopy will make us more inclined to repair a torn meniscus. The situation of the athlete with an isolated meniscal tear remains a dilemma. The clinician must balance the patient’s desire for a quick return to sporting activity against the longer-term aim of maintaining the most normal joint mechanics and potential protection against premature arthrosis. We advise limiting sporting activity beyond the resolution of symptoms. Our preferred rehabilitation programme is outlined later. 6. Techniques of meniscal repair Meniscal repair techniques have been developed and refined over the years. A combination of techniques may be used to adequately stabilise a particular meniscal tear. Common to every type of meniscal repair is preparation of the meniscus and the local environment. Any loose or frayed fragments of meniscus are removed
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Fig. 7. FasT-Fix device. (Smith & Nephew)
and the opposing edges are rasped to ‘freshen’ the surfaces. It is also recommended that abrasion of the local synovium be routinely performed. 6.1. Open With the advent of arthroscopic repair techniques, the need for an open meniscal repair is becoming less common. Indications for an open repair might include a very tight medial compartment preventing adequate access to the posterior horn or at the time of an acute complex knee ligament repair where a wide exposure is often already obtained. Similarly, if there are significant concerns regarding risks of neurovascular injury in posteriorly placed tears, then an open approach may be advised. The approach has been well described by DeHaven et al. w11,21x. The capsule is typically incised posterior to the collateral ligament and the synovium opened to give direct access to the meniscus. 6.2. Outside-in The outside-in technique w22x involves an open approach to the postero-medial or postero-lateral joint lines. Sutures are introduced into the knee through the lumen of a standard spinal needle, where they are visualised by the arthroscope. The suture is the drawn through a portal and an interference knot tied. The knot is pulled back into the knee where it snugs down the torn meniscal fragments. The process is repeated and finally the free suture ends are tied over the capsule. This technique is perhaps only suited for longitudinal tears but is useful in the unusual situation of a longitudinal tear of the anterior horn where arthroscopic access is limited. 6.3. Inside-out The inside-out technique utilises sutures placed in the menisci from within and then tied over the capsule through a limited open approach. There are a number
of commercially available systems for this technique. These comprise a system of curved cannulae to access the torn region of the meniscus. The suturing is achieved by passing long needles, with a suture attached, through the cannula and then through the meniscus to exit postero-mediallyylaterally. After the first needle is passed, the cannula is repositioned and the second needle is passed and retrieved. Before suturing it is best to make a 5 cm incision postero-mediallyylaterally, open the retinaculum and dissect to expose the joint capsule and the plane between it and the gastrocnemius. A ‘spoon’ retractor is used to divert the needles and protect the posterior soft tissues. The sutures are retrieved from deep to the gastrocnemius and retinaculum and are tied against the joint capsule. 6.4. All inside These arthroscopic techniques utilise arrows, darts and other devices designed to hold the meniscal fragments together while healing occurs. They have become increasingly popular, as they do not necessitate an additional skin incision. However, some of these devices have demonstrated inferior mechanical properties compared with suturing w23x. Our experience has been mixed and complications related to their use and insertion technique are still recognised w24x. Nevertheless, for very posterior tears or those requiring limited further stability, we feel there is still a place for an all-inside device. When indicated, we currently favour the FasT-fix meniscal repair system (Smith & Nephew, Endoscopy Division, Andover, MA) (Fig. 7). The device consists of a delivery system for two 5 mm polymer suture anchor bars connected with a pre-tied self-sliding nonabsorbable suture. These are placed sequentially, in either a horizontal or vertical alignment, and tightened with knot pusher obviating the need for arthroscopic knot tying.
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posterior suturing. In our series, the mean number of sutures andyor devices used was 3.6, with a range of 1–12. Once suture placement is complete, the suture ends are cleaned and then brought up through the surgical incision using an arthroscopy hook. They are then snugged down and tied over the capsule and satisfactory stability is confirmed with the arthroscope. Closure is performed in the usual way. 8. Adjuncts to healing Fig. 8. (a) The needle shuttle is passed through the meniscus to exit through the skin. The suture is threaded through the eye. (b) The needle is bought into the joint, repositioned on the meniscus in a vertical configuration and passed through the capsule and skin. The suture is retrieved to be tied over the joint capsule.
7. Author’s preferred technique The senior author prefers an inside-out technique, performed using a cannula and needle shuttle system. Unfortunately, these are no longer commercially available but an improved system is being developed. Other variations in this technique have been described w22x. Firstly, limited postero-medial or postero-lateral exposure as described above is made. The torn meniscal edges are prepared arthroscopically. The cannula is placed against the meniscus and the needle is passed through the meniscus under arthroscopic control and advanced through the skin. For posterior suture placement, a more curved cannula and needle is used and the needle system is levered (cautiously to prevent bending or breakage) medially or laterally to avoid the posterior neurovascular structures. In addition, having the leg positioned on the operating table flexed to 70–908 encourages the neurovascular structure to fall posteriorly. Most frequently the needle exits through the skin near the surgical incision. The suture is introduced through the eye on the concave surface of the needle for a distance of 5 cm. The needle and suture is drawn back into the joint, the cannula repositioned and the needle is reapplied through the meniscus and the skin. The suture is retrieved from the needle and clamped for later tying, usually after ACL graft fixation. A combination of sutures, 2y0 PDS and 2y0 Ethilon (Ethicon, Johnson & Johnson Intl, Brussels, Belgium), placed every 4–5 mm is typically used. Placement is alternated to the superior and inferior surfaces of the meniscus aiming for as vertical arrangement as possible. The vertical configuration is preferred to the horizontal orientation as there is evidence that the pull out strength is improved w25x (Fig. 8). Since the availability of all inside devices, often a combination of sutures and devices is used. The use of one or two devices posteriorly, along with sutures for the body of the repair, has reduced risks associated with
A variety of adjuncts to promote successful meniscal healing have been described. Abrasion of the adjacent synovium with a rasp or arthroscopic punch leads to bleeding in the region of the repair and it is felt that the release of tissue repair factors into the local environment will be beneficial. We feel that this is a simple procedure that can be performed for every meniscal repair. The use of fibrin clot has been shown to stimulate repair in dogs w26x. The fibrin is obtained from 70 ml of blood drawn per-operatively and is then incorporated into the repair. This has been recommended for complex tears and those extending into the avascular zone w22x. Vascular access channels are another means of improving the blood supply to the healing meniscus w14,27x. After repair the meniscus is ‘needled’ arthroscopically to encourage bleeding, and hence fibrin clot, into the repair site. 9. Difficult repairs Some meniscal tears may not appear repairable. However, if the clinical situation indicates that loss of the meniscus would be significantly detrimental to the function of the knee, then repair should be attempted, even in difficult circumstances. Such situations are a radial tear of the lateral meniscus in an ACL deficient knee with lateral compartment chondral damage or a detachment of the posterior horn of the medial meniscus in a varus-aligned patient. In these situations, the senior author has attempted repair and, somewhat surprisingly, the meniscus has healed (or rather not appeared to have failed) in the majority of these cases. Radial tears of the posterior horn of the lateral meniscus occur usually at the time of ACL injury. Some of these may heal spontaneously but to excise or saucerize the tear is to completely defunction the lateral meniscus. Repair can be achieved by placing 2 or 3 horizontal sutures across the tear (Fig. 5). Posterior horn avulsion tears effectively result in loss of meniscal function. The posterior horn tag will rarely catch unless the meniscus tears further. Yet removal of the tag denies the meniscus the opportunity to stabilise or be repaired. These can be readily repaired by placing two sutures through the horn and often another through
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Fig. 9. A posterior horn detachment can be effectively repaired by placing sutures through the horn and sometimes the posterior capsule. The sutures are then pulled through a previously drilled tibial tunnel.
the adjacent capsule using a suture punch. A 4-mm tunnel is drilled to the posterior horn insertion using an ACL guide and the adjacent area is abraded to bleeding bone. The sutures are then pulled through this tunnel and tied anteriorly. If a posterior horn avulsion tear of the lateral meniscus is being repaired at the time of an ACL reconstruction then the sutures can be pulled through and fixed within the ACL tibial tunnel (Fig. 9). Double bucket handle tears usually occur after repeated episodes of instability in ACL deficient knees. Occasionally they are seen in acute injuries as a shredded tear. These can be repaired in the usual fashion (Fig. 10). If, in the chronic situation, the central portion is very thin and extends to the vascular zone then it can be excised and the major remaining segment repaired with multiple sutures (Fig. 4).
10. Personal experience and results There are several problems when addressing the outcomes of meniscal repair surgery. Firstly, the method of assessing whether healing occurs or not would ideally involve a second-look arthroscopy but this is not routinely performed and cannot readily be justified on clinical grounds. Surrogates such as MRI scanning and arthrography have been used but both have limitations. MRI although now very sensitive in detecting soft tissue abnormalities, has difficulty in reliably demonstrating healing as abnormal signals persist making new and old pathology difficult to interpret w28x. Without considering the cost implication, we do not routinely order followup MRI scans in asymptomatic patients.
Fig. 10. A double longitudinal tear in the lateral posterior horn. Sutured both above and below the meniscus.
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Furthermore, whether the meniscus stays healed in the long-term remains unclear and perhaps, more importantly, are the biomechanical properties of the healed meniscus similar to the normal meniscus? Does a repaired meniscus transmit load and prevent against premature osteoarthrosis in the way that we would wish? A recent review of our operative database has revealed the senior author has performed 288 meniscus repairs in 265 patients over the last 12 years. Most patients were undergoing ACL reconstruction at the same time although 55 repairs have been performed as isolated procedures. In keeping with other authors, the medial meniscus was repaired around twice as often as the lateral meniscus. One hundred and eighty-one of the patients were male, 84 female with 145 cases involving the right knee and 120 cases the left knee. Twenty-three patients had both medial and lateral meniscal repairs. The most common orientation of tear was longitudinal (243 cases) but 9 were radial, 14 partial thickness and 22 complex in nature. The age range of patients has been 12–70 years with a mean of 26.6 years. Recent work has suggested that the patient’s age may not be the major problem once thought w17,29x. The mean time from injury to surgery was 11.7 months (range 1–72 months). Less than 1% of repairs involved the anterior horn. Approximately one third of patients undergoing meniscal repair had areas of chondral damage of at least Outerbridge grade 2. We have traditionally used clinical follow-up to assess our success rate but acknowledge there must be an unknown, asymptomatic failure rate. Nevertheless, our patient group is loyal and we are only aware of 10 patients who have required subsequent partial menisectomy. This represents 3.5% of the patient group that are known to be true failures. We have, however, documented 7 other patients who have undergone re-suturing of their meniscal tears but have then become asymptomatic. This suggests that our known meniscal repair failure rate is 5.9% but does highlight the possibility that unhealed tears that remain suitable for salvage can be re-sutured with apparently successful outcomes. We accept that there must be other patients whose repair has failed and have been treated elsewhere. For the purposes of this paper, no formal attempt at follow-up has been made. Clinical assessments are likely to overestimate success rates compared with anatomical criteria but from a pragmatic viewpoint, the patient views absence of symptoms as a success. Morgan et al. performed second-look arthroscopies on a cohort of patients and found that the patients with anatomic failures were symptomatic while those that had healed menisci remained asymptomatic w30x. Now there are a number of studies reporting good clinical success in the long-term w19,10,31,32x. These studies have shown success rates ranging from 69 to
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79% at 10 years. These were mainly peripheral, longitudinal tears, which can be considered to be those most likely to heal, but performed at a time when repair techniques were still being developed. In the shorter term, healing rates ranging from 63 to 91% have been reported w33x. A number of factors appear to influence this. As discussed already, peripheral tears, with their greater vascularity, heal more readily. Even for tears extending into the avascular zone, acceptable results have been obtained with a documented failure rate of 33% but absence of symptoms in 80% w34x. It is now also well accepted that meniscal repairs performed at the time of ACL reconstruction have a higher healing potential than isolated repairs w19,30,34x. Presumably this is due to increased bleeding following the more extensive procedure and the concomitant protection provided by the stabilised joint. Similarly, meniscal repairs performed in an ACL deficient knee have a higher failure rate than those in stable or near stable knees w19x. Nevertheless, in low demand patients, acceptable results for isolated meniscal repair in ACL deficient knees have been reported w35x. Repair of more acute tears (i.e. less than 8 weeks old) seem to be associated with better results w19,31x. Medial meniscal repairs, particularly of a posterior horn, are more likely to fail than repair of the lateral meniscus w34x. The more extensive and complex tears are more likely to fail and this occurs most frequently within the first 6 months w31x. 11. Complications As with any surgical procedure, all techniques of meniscal repair carry the risk of complications. These may be general such as superficial and deep infection, deep vein thrombosis, arthrofibrosis and complex regional pain syndromes. Injuries to the common peroneal nerve laterally, the saphenous nerve medially and the popliteal arteries posteriorly, are of greatest concern. Fortunately, major complications are very rare w36x. Nevertheless, some authors recommend a wider exposure to ensure adequate protection of the neurovascular structures with a potential reduction in serious complications w22x. Generally, we have not found this necessary. In this series there have been three significant complications. Early in the series, there were two cases of septic arthritis both treated successfully by early arthroscopic washout and excision of the meniscus fragment and the suture material. One of these patients returned to International level Rugby League football. As a consequence, we have ceased using braided sutures for this technique and have seen no further infections in the last 10 years. There has been one case of peroneal nerve neuropraxia, which resolved completely by 6 weeks post-operatively.
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12. Post-operative rehabilitation The optimum post-operative management protocol for isolated meniscal repairs continues to develop and still remains controversial. Fundamentally, the aim is to protect the meniscus while healing progresses and then perform a phased return to activity while maturation of the scar occurs, so permitting more vigorous activity. Some surgeons are more conservative and others are more aggressive in their post-operative management. Our approach appears to be in the ‘middle ground’. Our typical routine for isolated repairs is to maintain the knee in a Velcro-type splint for 3–4 weeks. During this time simple isometric quadriceps exercises and early range of motion are performed. For longitudinal tears, weight bearing per se in the extended position may, however, not be a significant factor, as it will, tend to force the meniscal fragments together. Nevertheless, patients are usually kept touch weight bearing with crutches for 2 weeks before progressing to partial and then protected weight bearing over the next 4 weeks. The main aim during this time is to prevent shear stresses from occurring and this typically occurs during weight bearing under load. Range of motion is generally limited to 0–908 for 6 weeks. Deep squats should be avoided for 3 months and deep squats with load, as a muscle strengthening exercise should probably be discouraged from further use. Improvement in quadricepsy hamstring balance along with strength and endurance exercises are encouraged to improve the ‘external’ shock absorbers of the knee. Return to sporting activity will typically be introduced at 12–16 weeks. With meniscal repair undertaken at the time of ACL reconstruction, our standard ACL rehabilitation programme is slowed down by approximately 1 week over the first 6 weeks, so that a brace and partial weightbearing is maintained until 3 weeks rather than the typical 2 weeks for isolated ACL reconstructions. Knee bend beyond 908 is not pushed until 6 weeks. From this point on, our routine ACL rehabilitation programme is followed. The return to more dynamic activities such as running is not introduced until 16 weeks with the introduction of sports specific drills at 5–6 months. Accelerated rehabilitation protocols have been described allowing full weight bearing, no immobilisation and returning to sport and pivoting activities as soon as the patient’s knee is functioning well and inflammation is settled w37x. However, it is unlikely that one schedule will fit all patients. The need to accommodate the nature of the tear, concurrent procedures, such as associated ligament reconstruction, and method of repair used are all likely to have an influence on healing rates.
13. Summary Long-term studies have shown both total and partial menisectomy to be associated with premature degenerative change of the knee. Although treatments of articular surface injury remain in their infancy, proven techniques for repair of meniscal tears are now available. When meniscal salvage is possible, preservation of the menisci is advised, particularly in the setting of anterior cruciate ligament deficiency. The meniscus’ contribution to knee joint stability and the higher healing rates in this setting are emphasised. Arthroscopic surgeons should develop a range of meniscal repair techniques to allow them to address tears of differing complexity and location. Attention to biological and biomechanical factors and the use of various adjuncts to promote healing are likely to permit high healing rates for some tears that have traditionally been felt to be irreparable. We recommend that meniscal repair should be attempted if a good clinical indication for meniscal preservation exists, even if the appearances are not classically favourable. References w1x Fairbank TJ. Knee joint changes after menisectomy. J. Bone Joint Surg. wBrx Part B 1948;30:664 –670. w2x Johnson RJ, Kettlekamp DB, Clark W, et al. Factors affecting late results after menisectomy. J Bone Joint Surg wAmx Part A 1974;56:719 –729. w3x McGinty JB, Guess LF, Marvin RA. Partial or total menisectomy: a comparative analysis. J Bone Joint Surg wAmx Part A 1977;59:763 –766. w4x Northmore-Ball MD, Dandy DJ, Jackson RW. Arthroscopic, open partial and total menisectomy. A comparative study. J Bone Joint Surg wBrx Part B 1983;65:400 –404. w5x Rangger C, Klestil T, Gloetzer W, Kemmler G, Benedetto KP. Osteoarthritis after arthroscopic partial menisectomy. Am J Sports Med 1995;23:240 –244. w6x Aspden RM, Yarker YE, Hukins DWL. Collagen orientations in the meniscus of the knee joint. J Anat 1985;140:371 –380. w7x Ahmed AH, Burke DL. In-vitro measurement of static pressure distribution in synovial joints—part 1: tibial surface of the knee. J Biomech Eng 1983;105:216 –225. w8x Thompson WO, Thaete FL, Fu F, Dye SF. Tibial meniscal dynamics using three-dimensional reconstruction of magnetic resonance images. Am J Sports Med 1991;19:210 –216. w9x Baratz ME, Fu F, Mengato R. Meniscal tears: the effect of menisectomy and of repair on intra-articular contact areas and stresses in the human knee. Am J Sports Med 1986;14:270 – 275. w10x Levy IM, Torzilli PA, Warren RF. The effect of medial menisectomy on the anterior–posterior motion of the knee. J Bone Joint Surg wAmx Part A 1982;64:883 –888. w11x DeHaven KE, Arnoczky SP. Meniscal repair. Part I. Basic science, indications and open repair. J Bone Joint Surg wAmx Part A 1994;76:140 –152. w12x Assimakopoulos AP, Katonis PG, Agapitos MV, Exarchou EI. The innervation of the human meniscus. Clin Orthop 1992;275:232 –236. w13x King D. The healing of semilunar cartilages. J Bone Joint Surg 1936;18:333 –342.
K.T. Boyd, P.T. Myers / The Knee 10 (2003) 1–11 w14x Arnoczky SP, Warren RF. The microvasculature of the meniscus and its response to injury. An experimental study in the dog. Am J Sports Med 1983;11:131 –141. w15x Arnoczky SP, Warren RF. Microvasculature of the human meniscus. Am J Sports Med 1982;10:90 –95. w16x Roeddecker K, Muennich U, Nagelschmidt M. Meniscal healing: a biomechanical study. J Surg Res 1994;56:20 –27. w17x 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. w18x Annandale T. An operation for displaced semilunar cartilage: 1885 wclassical articlex. Clin Orthop 1990;260:3 –5. w19x DeHaven KE, Lohrer WA, Lovelock JE. Long-term results of open meniscal repair. Am J Sports Med 1995;23:524 –530. w20x Rockborn P, Gillquist J. Results of open meniscus repair. Longterm follow-up study with a matched uninjured control group. J Bone Joint Surg wBrx Part B 2000;84:494 –498. w21x DeHaven RE, Black K, Griffiths HJ. Open meniscus repair. Technique and two to nine year results. Am J Sports Med 1989;17:788 –795. w22x Cannon WD, Morgan CD. Meniscal repair. Part II: arthroscopic repair techniques. J Bone Joint Surg wAmx Part A 1994;76:294 – 311. w23x 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. w24x Calder SJ, Myers PT. Broken arrow: a complication of meniscal repair. Arthroscopy 1999;15:651 –652. w25x Rimmer MG, Nawana NS, Keene GCR, Pearcy MJ. Various strengths of different meniscal suturing techniques. Arthroscopy 1995;11:146 –150. w26x Arnoczky SP, Warren RF, Spivak JM. Meniscal repair using an exogenous fibrin clot. An experimental study in dogs. J Bone Joint Surg wAmx Part A 1988;70:1209 –1217.
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w27x Zhang Z, Arnold JA, Williams T, McCann B. Repairs by trephination and suturing of longitudinal injuries in the avascular area of the meniscus in goats. Am J Sports Med 1995;23:35 –41. w28x Farley TE, Howell SM, Love KF, Wolfe RD, Neumann CH. Meniscal tears: MR and arthrographic findings after arthroscopic repair. Radiology 1991;180:517 –522. w29x Barrett GR, Field MH, Treacy S, Ruff CG. Clinical results of meniscus repair in patients 40 years and older. Arthroscopy 1998;14:824 –829. w30x Morgan CD, Wojtys EM, Casscells CD, Casscells SW. Arthroscopic meniscal repair evaluated by second-look arthroscopy. Am J Sports Med 1991;19:632 –637. w31x Eggli S, Wegmuller H, Kosina J, Hucknell C, Jakob RP. Longterm results of arthroscopic meniscal repair. An analysis of isolated tears. Am J Sports Med 1995;23:715 –720. w32x Lucas GL, Dusek JK, Henning CE. Isolated arthroscopic meniscal repair: a long-term outcome study (more than 10 years). Am J Sports Med 1999;27:44 –49. w33x DeHaven KE. Meniscus repair. Am J Sports Med 1999;27:242 –250. w34x 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;28:87 –95. w35x Hanks GA, Gause TM, Handal JA, Kalenak A. Meniscus repair in the anterior cruciate deficient knee. Am J Sports Med 1990;18:606 –613. w36x Small NC. Complications in arthroscopic surgery performed by experienced arthroscopists. Arthroscopy 1988;4:215 –221. w37x Barber FA. Accelerated rehabilitation for meniscus repairs. Arthroscopy 1994;10:206 –210.
Review
Meniscus preservation; rationale, repair techniques and results夞 Kevin T. Boyd, Peter T. Myers* Brisbane Orthopaedic and Sports Medicine Centre, Holy Spirit Hospital, 259 Wickham Terrace, Brisbane 4000, Australia Received 21 October 2002; received in revised form 15 November 2002; accepted 24 November 2002
Abstract It is inescapable that loss of part or all of the structure of the meniscus of the knee alters the biomechanics of knee function leading to a gradual deterioration of the chondral surface, which ultimately will result in osteoarthritis. The goal of the knee surgeon should therefore be to preserve as much as possible the function of the meniscus. Classic teaching is that many meniscal tears, which are peripheral and longtitudinal, will heal if sutured and protected during a slow healing process. However it is clear that other tear configurations can heal if given the opportunity by adequate preparation of the meniscus rim, careful suturing and delayed rehabilitation. Thus some radial tears, horn avulsions, double longtitudinal tears and retears, previously thought to be irreparable, can be sutured with good results. Over 12 years, 288 meniscus repairs were undertaken in 265 patients ranging in age from 12 to 70 years. Most were repaired at the time of anterior cruciate ligament reconstruction, although 55 were isolated repairs. While the average time from injury to surgery was 11.7 months (1 – 72), one third of patient’s already had chondral damage of at least Outerbridge Grade 2. The purpose of this paper is to report on the more difficult meniscus repair techniques and as such formal follow up was not undertaken to determine the final outcome of these patients. Never the less it is estimated from known data that there was a retear rate in the order of less than 10%. There have been three complications, 2 infections and one temporary neuropraxia of the common peroneal nerve; all of these healed completely with appropriate treatment. Therefore we recommend that meniscus repair should be undertaken if a clinical case for meniscal preservation exists, even if the appearances are not those classically recommended. 䊚 2002 Elsevier Science B.V. All rights reserved. Keywords: Meniscus; Menisectomy; Arthroscopy; Meniscus repair
1. Introduction Meniscal tears are a common and important source of knee dysfunction, particularly in younger, active individuals who place significant demand on their knees. The menisci are now recognised to be integral parts of the biomechanical function of the knee and not the vestigial and dispensable remains of evolution as once thought. Although Fairbank, in 1948, clearly demonstrated the radiological consequences for the knee of total menisectomy w1x, this remained the widespread treatment of meniscal tears until the 1970s. 夞 This review article is based on a presentation given at the COKS meeting in Cape Town during March 2002. *Corresponding author. E-mail address: [email protected] (P.T. Myers).
Over the last two decades, with the general adoption of arthroscopy, there has been an improvement in surgical techniques to assess and treat meniscal pathology. These improvements along with an enhanced understanding of the biomechanical properties of the menisci have led to a shift towards preservation of the menisci w2–4x. Meniscal preservation includes leaving small or partial tears, partial menisectomy and meniscus repair techniques. Partial menisectomy, where only the damaged, unstable portion of the meniscus is removed leaving the remainder intact has become almost the routine treatment for damaged menisci. Nevertheless, partial menisectomy has also been shown to be associated with an increased incidence of degenerative changes w5 x . In an attempt to maintain as near normal a knee as possible, techniques for meniscal repair and adjuncts to
0968-0160/03/$ - see front matter 䊚 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 6 8 - 0 1 6 0 Ž 0 2 . 0 0 1 4 7 - 3
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Fig. 1. A compressive force (white arrow) is converted by the shape of the meniscus to a radially directed force (black arrows), which is taken up as a tension force (dashed arrow) within the meniscus.
promote meniscal healing have been developed. Meniscal fragments, which otherwise would have been excised, can now be retained. These techniques can be demanding and the criteria for repair continue to be defined. This paper is a personal review of the rationale for meniscal preservation and introduces the techniques and experience of the senior author (P.T.M.). 2. Meniscal biomechanics The main function of the menisci is one of load transmission. The majority of the collagen fibres are large and coarse and are arranged in a circumferential manner. These fibres are stabilised with radially running fibres acting as ties. This structure suggests the ability to bear load is by containment of the so-called ‘hoop stresses’ w6x (Fig. 1). It has been determined that approximately 50% of the body’s weight is transmitted through the menisci in extension and up to 85% in 908 of flexion w7x. The menisci, however, are mobile structures that move ante-
Fig. 2. With ACL deficiency an anteriorly directed force (white arrow) is partly resisted by an intact medial meniscus (black arrow). If the meniscus is also deficient then the tibia can move further anteriorly (adapted from Ref. w10x).
riorly and posteriorly to allow maintenance of congruency throughout the range of flexion. The radius of curvature also changes to accommodate the reduced radius of the femoral condyles as flexion and rollback occurs w8x. The medial meniscus is more restrained than the lateral meniscus, particularly in the postero-medial corner, and this may explain why tears of this area are more common. It is now well accepted that loss of all or part of a meniscus increases point loading and results in premature wear of the knee due to altered mechanical forces. The rate at which arthrosis develops, however, depends on a number of factors and these may be regarded as knee factors and patient factors. The volume of meniscus lost has been considered. Total menisectomy has been estimated to reduce the joint surface contact area by 75%, increasing local peak contact pressure by 235%. Partial menisectomy also reduces contact area by 10% and increases point pressures by 65% w9x. The nature of the tear is important. Radial tears extending to the periphery may not result in much volume loss but may completely defunction the meniscus through an inability to resist hoop stresses. Associated injuries either at the time of meniscal tear or subsequently, such as chondral damage and anterior cruciate ligament rupture, will also have a significant effect on the knee’s long-term prognosis. Patient factors include limb alignment, age at time of injury, activity level, weight and inherent genetic constitution. The menisci also act as secondary stability restraints in the knee. The effect in a stable knee remains controversial but in an ACL deficient knee there is no doubt that loss of a meniscus increases measurable joint laxity. In these situations, it is suggested that the intact posterior horn of the medial meniscus acts as a wedge or ‘stop’ to anterior translation of the tibia w10x (Fig. 2). Unfortunately, it is not uncommon to witness an ACL deficient knee in an active individual sequentially undergoing medial and lateral menisectomies with a rapid progression to premature arthrosis. Further biomechanical functions of the menisci have been postulated. These include shock absorption, lubrication, joint nutrition and proprioception w11x. The menisci exhibit viscoelastic properties, which may serve to attenuate impacts sustained through the knee on loading. The improved congruity that they provide has been suggested to aid joint lubrication and cartilage nutrition by promoting fluid shifts in and out of the cartilage surface layers. Recent studies have shown the presence of mechano-receptors and free nerve endings in the peripheral, two thirds of the meniscus body and the horns, particularly the posterior horns w12x. This suggests an important role of the menisci in proprioceptive feedback, the initiation of protective reflexes and joint pain. This may also explain why meniscal tears without a significant mechanical component can still be a source of painful symptoms.
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3. Meniscal healing The capacity of meniscus to heal is limited, particularly the central portions, which are largely avascular, aneural and alymphatic. However, in 1936, King showed that meniscal healing in dogs could occur providing there was communication with the peripheral blood supply w13x. As with other soft and bony tissues, there is a need for a balance between blood supply, and hence associated cellular and tissue repair factors, and component stability to permit healing. The process would appear to be along the same lines as healing in other soft tissues and, in the vascular portion of the meniscus, it would appear that healing is largely complete by 10 weeks w14x, although maturation of the scar may continue for many months. As indications for meniscal repair are extended, attempts to promote an environment more conducive to healing have been introduced. The vascular anatomy of the human meniscus has been well described by Arnoczky and Warren w15x. The blood supply is by way of the superior and inferior medial and lateral geniculate arteries. The outer rim of the meniscus is vascularized up to 30% of its width on the medial side and 25% on the lateral side. In addition, there is a synovial fringe that extends some 3 mm over the surface of each meniscus adding further to the peripheral vascularity. The concept of ‘red-on-red’, red-on-white’ and ‘whiteon-white’ tears, describing the vascular status of each tear location, is a useful classification. ‘Red-on-red’ tears are perhaps a misnomer as all tears must be ‘redon-white’, as the central portion, by its nature, must have had its vascular supply disrupted. Nevertheless, it is a reflexion of the peripheral location and is a good indicator that healing should occur. ‘White-on-white’ tears are located within the avascular zone and hence have the least potential to heal. The majority of reports on meniscal repair address primarily longitudinal tears, which are indeed the commonest tear to be repaired. Current practice suggests that certain tears are incapable of healing although anecdotally this has not been our experience. As with any scarred tissue, it is likely, however, that even fully healed menisci will not regain normal biomechanical strength. Indeed, there is some evidence at 12 weeks after meniscal suture, meniscal strength may be significantly reduced at only 26% of the normal side w16x. 4. Nature of tears Meniscal tears are most commonly described on the basis of their anatomical location and appearance. They may also be partial- or full-thickness. Partial thickness tears can generally be left alone to heal by themselves. Despite the recent advances in MRI scanning, arthroscopic assessment remains the definitive technique of
Fig. 3. Repair of a displaced medial bucket handle tear.
tear identification. However, other features such as whether the torn fragment has itself been damaged will influence the decision to repair or resect. In the past, we have perhaps been too hasty to excise a meniscus just because it is torn without due consideration as to whether it was, in fact, the cause of the symptoms and whether it might heal if left well alone. The types of meniscal tears are discussed as follows. 4.1. Vertical (longitudinalycircumferential) tears This is the more common type to be repaired. The classical configuration of a meniscus tear suitable for repair is a full-thickness, vertical tear extending less than 2 cm with no associated damage and within 2 mm of the periphery. In addition, it is recommended that the tear be relatively fresh, be in a young patient and the knee otherwise stable w11x. It would be fair to say that ‘best practice’ would be to always repair a meniscus tear of this description, as the likelihood of healing is approximately 85%. However, these are not the only tears that can heal given satisfactory stability and biology. The unstable, longitudinal tear, the ‘bucket handle’ tear, can also be addressed. Due to their extensive nature, excision of these may well result in subtotal menisectomy and should be avoided if the displaced fragment is of sufficiently good quality (Fig. 3). A double bucket handle tear can be seen in the ACL deficient knee
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Fig. 4. Repair of a double bucket handle tear of the medial meniscus showing abrasion of the rim (1), the peripheral or ‘2nd handle’ fragment (2), a suture being placed (3) and the finished 8-suture repair.
following repeated injuries during episodes of giving way. These too can be repaired and go onto heal, although the more peripheral ‘bucket handle’ portion may need to be excised (Fig. 4). 4.2. Radial tears Radial tears of the lateral meniscus are commonly seen following ACL disruption. If small, these can be simply saucerized. Radial tears that extend to the periphery are significant injuries as they disrupt the ability of the meniscus to contain hoop stresses (Fig. 1). Traditionally, it has been felt inappropriate to repair these. Nevertheless, we, along with others have seen tears of this nature heal with meniscal repair w17x (Fig. 5). 4.3. Horizontal (cleavageytransverse) tears These tears are difficult to manage and, in our experience, are not suitable for repair. Typically, they develop in the early degenerate meniscus due to differential shear stresses between superior and inferior leaves of the meniscus. They may be associated with meniscal cyst formation if there is a communication to the
Fig. 5. A posterior horn radial tear is repaired by using 2 or 3 horizontal sutures.
periphery. We recommend excision of the inferior leaf of the meniscus, attempting to leave the superior leaf intact. The pre-horizontal tear (a contained split within the meniscus but before rupture into the joint has occurred) is a particularly difficult management problem (Fig. 6). Here the patient has localising symptoms and an abnormal meniscus signal (grade 2) on MRI. Yet there is no apparent tear at arthroscopy and no other source of pathology can be identified. Following appropriate discussion with the patient, we have opened such menisci and found an established horizontal split within the meniscus substance. Treatment along the lines outlined above has relieved symptoms. 4.4. Degenerate tears These tears may be of a variety of configurations and can be a source of new or increased symptoms in an arthritic knee. Meniscal degeneration is evident bio-
Fig. 6. A transverse degeneration of the posterior horn of the medial meniscus is shown with out connection to the articular surface.
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chemically in the fourth decade of life. Usually, the meniscus is of poor quality and is typically excised back to a stable rim. Unfortunately for the patient, although they may be relieved of symptoms pertaining to the tear, overzealous excision of the degenerate body of the meniscus may expose worn joint surfaces with a continuation, or worsening, of painful symptoms. Fortunately, these tend to occur in the ageing population where alternative treatment options exist for end-stage arthrosis and continuing disabling symptoms. 4.5. Complex tears These are tears in two or more planes within a meniscus. It is generally recommended that these are excised and yet recent experience is challenging the fact that these tears are unrepairable. If the clinical situation strongly suggests the patient will benefit from meniscal preservation then repair of these tears can be performed attending to basic principles. The oblique or parrot beak tear represents a type of complex tear. These can have a wide variety of configurations and like radial tears can have significant consequences for knee biomechanics if they extend to the periphery. 4.6. Horn detachments These are included, as even though the meniscus substance may be intact the biomechanical qualities will be significantly affected. Usually, the posterior horns are affected. In these circumstances, we recommend reattachment of the posterior horn as described below. 5. Treatment options Accurate arthroscopic visualisation is important to define the extent and nature of the tear. Only when this has been adequately assessed, can an informed decision about treatment be made. Both the upper and lower surfaces of each meniscus can usually be fully assessed with the use of an arthroscopic hook or probe. 5.1. Leave alone Partial thickness tears or full-thickness tears (-8 mm) are rarely a cause of mechanical symptoms and there is a good likelihood of spontaneous healing particularly after a recent injury. This may be promoted by adjuncts to healing such as local synovial abrasion. The simple presence of a meniscal tear does not always mean that a partial menisectomy must be performed! 5.2. Excision It is not so long ago that the traditional orthopaedic management of a suspected meniscal tear was open total
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menisectomy. Fortunately, for the patient, this type of treatment is now confined to the history books. Arthroscopic partial menisectomy is the most common treatment undertaken and is normally effective in eliminating mechanical and irritative symptoms associated with a damaged meniscus. This may also be beneficial by reducing the incidence of articular surface damage through recurrent chaffing and catching of a meniscal fragment between joint surfaces. Nevertheless, the biomechanical properties of the knee’s ability to withstand loads will be affected by partial menisectomy. We feel it is important to advise patients of this and recommend that they maintain good endurance and tone in their quadriceps musculature and be conscious of the degree of impact loading that they subsequently undertake. 5.3. Repair Annandale is credited with the first meniscal repair in 1885 w18x. A more aggressive approach to meniscal preservation, particularly in knees undergoing ACL reconstruction, is becoming more commonplace. The immediate goals are to maintain the ability of the meniscus to transmit load and provide stability. In the longer-term this may prevent or, at least, reduce the risk of progression to premature osteoarthrosis. Maintenance of an intact functioning meniscus is felt to be one of the major factors in reducing the risk of progression to radiographic changes of arthritis w19,20x. The ability to pre-operatively identify patients suitable for meniscal repair would be ideal. This would aid the process of informed consent and the planning of theatre time. At present, however, the decision to repair or cannot made until the time of arthroscopy. The role of the meniscus in protecting the joint surfaces should be emphasised. The presence of valgusyvarus tendencies or evidence of established articular surface damage at arthroscopy will make us more inclined to repair a torn meniscus. The situation of the athlete with an isolated meniscal tear remains a dilemma. The clinician must balance the patient’s desire for a quick return to sporting activity against the longer-term aim of maintaining the most normal joint mechanics and potential protection against premature arthrosis. We advise limiting sporting activity beyond the resolution of symptoms. Our preferred rehabilitation programme is outlined later. 6. Techniques of meniscal repair Meniscal repair techniques have been developed and refined over the years. A combination of techniques may be used to adequately stabilise a particular meniscal tear. Common to every type of meniscal repair is preparation of the meniscus and the local environment. Any loose or frayed fragments of meniscus are removed
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Fig. 7. FasT-Fix device. (Smith & Nephew)
and the opposing edges are rasped to ‘freshen’ the surfaces. It is also recommended that abrasion of the local synovium be routinely performed. 6.1. Open With the advent of arthroscopic repair techniques, the need for an open meniscal repair is becoming less common. Indications for an open repair might include a very tight medial compartment preventing adequate access to the posterior horn or at the time of an acute complex knee ligament repair where a wide exposure is often already obtained. Similarly, if there are significant concerns regarding risks of neurovascular injury in posteriorly placed tears, then an open approach may be advised. The approach has been well described by DeHaven et al. w11,21x. The capsule is typically incised posterior to the collateral ligament and the synovium opened to give direct access to the meniscus. 6.2. Outside-in The outside-in technique w22x involves an open approach to the postero-medial or postero-lateral joint lines. Sutures are introduced into the knee through the lumen of a standard spinal needle, where they are visualised by the arthroscope. The suture is the drawn through a portal and an interference knot tied. The knot is pulled back into the knee where it snugs down the torn meniscal fragments. The process is repeated and finally the free suture ends are tied over the capsule. This technique is perhaps only suited for longitudinal tears but is useful in the unusual situation of a longitudinal tear of the anterior horn where arthroscopic access is limited. 6.3. Inside-out The inside-out technique utilises sutures placed in the menisci from within and then tied over the capsule through a limited open approach. There are a number
of commercially available systems for this technique. These comprise a system of curved cannulae to access the torn region of the meniscus. The suturing is achieved by passing long needles, with a suture attached, through the cannula and then through the meniscus to exit postero-mediallyylaterally. After the first needle is passed, the cannula is repositioned and the second needle is passed and retrieved. Before suturing it is best to make a 5 cm incision postero-mediallyylaterally, open the retinaculum and dissect to expose the joint capsule and the plane between it and the gastrocnemius. A ‘spoon’ retractor is used to divert the needles and protect the posterior soft tissues. The sutures are retrieved from deep to the gastrocnemius and retinaculum and are tied against the joint capsule. 6.4. All inside These arthroscopic techniques utilise arrows, darts and other devices designed to hold the meniscal fragments together while healing occurs. They have become increasingly popular, as they do not necessitate an additional skin incision. However, some of these devices have demonstrated inferior mechanical properties compared with suturing w23x. Our experience has been mixed and complications related to their use and insertion technique are still recognised w24x. Nevertheless, for very posterior tears or those requiring limited further stability, we feel there is still a place for an all-inside device. When indicated, we currently favour the FasT-fix meniscal repair system (Smith & Nephew, Endoscopy Division, Andover, MA) (Fig. 7). The device consists of a delivery system for two 5 mm polymer suture anchor bars connected with a pre-tied self-sliding nonabsorbable suture. These are placed sequentially, in either a horizontal or vertical alignment, and tightened with knot pusher obviating the need for arthroscopic knot tying.
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posterior suturing. In our series, the mean number of sutures andyor devices used was 3.6, with a range of 1–12. Once suture placement is complete, the suture ends are cleaned and then brought up through the surgical incision using an arthroscopy hook. They are then snugged down and tied over the capsule and satisfactory stability is confirmed with the arthroscope. Closure is performed in the usual way. 8. Adjuncts to healing Fig. 8. (a) The needle shuttle is passed through the meniscus to exit through the skin. The suture is threaded through the eye. (b) The needle is bought into the joint, repositioned on the meniscus in a vertical configuration and passed through the capsule and skin. The suture is retrieved to be tied over the joint capsule.
7. Author’s preferred technique The senior author prefers an inside-out technique, performed using a cannula and needle shuttle system. Unfortunately, these are no longer commercially available but an improved system is being developed. Other variations in this technique have been described w22x. Firstly, limited postero-medial or postero-lateral exposure as described above is made. The torn meniscal edges are prepared arthroscopically. The cannula is placed against the meniscus and the needle is passed through the meniscus under arthroscopic control and advanced through the skin. For posterior suture placement, a more curved cannula and needle is used and the needle system is levered (cautiously to prevent bending or breakage) medially or laterally to avoid the posterior neurovascular structures. In addition, having the leg positioned on the operating table flexed to 70–908 encourages the neurovascular structure to fall posteriorly. Most frequently the needle exits through the skin near the surgical incision. The suture is introduced through the eye on the concave surface of the needle for a distance of 5 cm. The needle and suture is drawn back into the joint, the cannula repositioned and the needle is reapplied through the meniscus and the skin. The suture is retrieved from the needle and clamped for later tying, usually after ACL graft fixation. A combination of sutures, 2y0 PDS and 2y0 Ethilon (Ethicon, Johnson & Johnson Intl, Brussels, Belgium), placed every 4–5 mm is typically used. Placement is alternated to the superior and inferior surfaces of the meniscus aiming for as vertical arrangement as possible. The vertical configuration is preferred to the horizontal orientation as there is evidence that the pull out strength is improved w25x (Fig. 8). Since the availability of all inside devices, often a combination of sutures and devices is used. The use of one or two devices posteriorly, along with sutures for the body of the repair, has reduced risks associated with
A variety of adjuncts to promote successful meniscal healing have been described. Abrasion of the adjacent synovium with a rasp or arthroscopic punch leads to bleeding in the region of the repair and it is felt that the release of tissue repair factors into the local environment will be beneficial. We feel that this is a simple procedure that can be performed for every meniscal repair. The use of fibrin clot has been shown to stimulate repair in dogs w26x. The fibrin is obtained from 70 ml of blood drawn per-operatively and is then incorporated into the repair. This has been recommended for complex tears and those extending into the avascular zone w22x. Vascular access channels are another means of improving the blood supply to the healing meniscus w14,27x. After repair the meniscus is ‘needled’ arthroscopically to encourage bleeding, and hence fibrin clot, into the repair site. 9. Difficult repairs Some meniscal tears may not appear repairable. However, if the clinical situation indicates that loss of the meniscus would be significantly detrimental to the function of the knee, then repair should be attempted, even in difficult circumstances. Such situations are a radial tear of the lateral meniscus in an ACL deficient knee with lateral compartment chondral damage or a detachment of the posterior horn of the medial meniscus in a varus-aligned patient. In these situations, the senior author has attempted repair and, somewhat surprisingly, the meniscus has healed (or rather not appeared to have failed) in the majority of these cases. Radial tears of the posterior horn of the lateral meniscus occur usually at the time of ACL injury. Some of these may heal spontaneously but to excise or saucerize the tear is to completely defunction the lateral meniscus. Repair can be achieved by placing 2 or 3 horizontal sutures across the tear (Fig. 5). Posterior horn avulsion tears effectively result in loss of meniscal function. The posterior horn tag will rarely catch unless the meniscus tears further. Yet removal of the tag denies the meniscus the opportunity to stabilise or be repaired. These can be readily repaired by placing two sutures through the horn and often another through
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Fig. 9. A posterior horn detachment can be effectively repaired by placing sutures through the horn and sometimes the posterior capsule. The sutures are then pulled through a previously drilled tibial tunnel.
the adjacent capsule using a suture punch. A 4-mm tunnel is drilled to the posterior horn insertion using an ACL guide and the adjacent area is abraded to bleeding bone. The sutures are then pulled through this tunnel and tied anteriorly. If a posterior horn avulsion tear of the lateral meniscus is being repaired at the time of an ACL reconstruction then the sutures can be pulled through and fixed within the ACL tibial tunnel (Fig. 9). Double bucket handle tears usually occur after repeated episodes of instability in ACL deficient knees. Occasionally they are seen in acute injuries as a shredded tear. These can be repaired in the usual fashion (Fig. 10). If, in the chronic situation, the central portion is very thin and extends to the vascular zone then it can be excised and the major remaining segment repaired with multiple sutures (Fig. 4).
10. Personal experience and results There are several problems when addressing the outcomes of meniscal repair surgery. Firstly, the method of assessing whether healing occurs or not would ideally involve a second-look arthroscopy but this is not routinely performed and cannot readily be justified on clinical grounds. Surrogates such as MRI scanning and arthrography have been used but both have limitations. MRI although now very sensitive in detecting soft tissue abnormalities, has difficulty in reliably demonstrating healing as abnormal signals persist making new and old pathology difficult to interpret w28x. Without considering the cost implication, we do not routinely order followup MRI scans in asymptomatic patients.
Fig. 10. A double longitudinal tear in the lateral posterior horn. Sutured both above and below the meniscus.
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Furthermore, whether the meniscus stays healed in the long-term remains unclear and perhaps, more importantly, are the biomechanical properties of the healed meniscus similar to the normal meniscus? Does a repaired meniscus transmit load and prevent against premature osteoarthrosis in the way that we would wish? A recent review of our operative database has revealed the senior author has performed 288 meniscus repairs in 265 patients over the last 12 years. Most patients were undergoing ACL reconstruction at the same time although 55 repairs have been performed as isolated procedures. In keeping with other authors, the medial meniscus was repaired around twice as often as the lateral meniscus. One hundred and eighty-one of the patients were male, 84 female with 145 cases involving the right knee and 120 cases the left knee. Twenty-three patients had both medial and lateral meniscal repairs. The most common orientation of tear was longitudinal (243 cases) but 9 were radial, 14 partial thickness and 22 complex in nature. The age range of patients has been 12–70 years with a mean of 26.6 years. Recent work has suggested that the patient’s age may not be the major problem once thought w17,29x. The mean time from injury to surgery was 11.7 months (range 1–72 months). Less than 1% of repairs involved the anterior horn. Approximately one third of patients undergoing meniscal repair had areas of chondral damage of at least Outerbridge grade 2. We have traditionally used clinical follow-up to assess our success rate but acknowledge there must be an unknown, asymptomatic failure rate. Nevertheless, our patient group is loyal and we are only aware of 10 patients who have required subsequent partial menisectomy. This represents 3.5% of the patient group that are known to be true failures. We have, however, documented 7 other patients who have undergone re-suturing of their meniscal tears but have then become asymptomatic. This suggests that our known meniscal repair failure rate is 5.9% but does highlight the possibility that unhealed tears that remain suitable for salvage can be re-sutured with apparently successful outcomes. We accept that there must be other patients whose repair has failed and have been treated elsewhere. For the purposes of this paper, no formal attempt at follow-up has been made. Clinical assessments are likely to overestimate success rates compared with anatomical criteria but from a pragmatic viewpoint, the patient views absence of symptoms as a success. Morgan et al. performed second-look arthroscopies on a cohort of patients and found that the patients with anatomic failures were symptomatic while those that had healed menisci remained asymptomatic w30x. Now there are a number of studies reporting good clinical success in the long-term w19,10,31,32x. These studies have shown success rates ranging from 69 to
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79% at 10 years. These were mainly peripheral, longitudinal tears, which can be considered to be those most likely to heal, but performed at a time when repair techniques were still being developed. In the shorter term, healing rates ranging from 63 to 91% have been reported w33x. A number of factors appear to influence this. As discussed already, peripheral tears, with their greater vascularity, heal more readily. Even for tears extending into the avascular zone, acceptable results have been obtained with a documented failure rate of 33% but absence of symptoms in 80% w34x. It is now also well accepted that meniscal repairs performed at the time of ACL reconstruction have a higher healing potential than isolated repairs w19,30,34x. Presumably this is due to increased bleeding following the more extensive procedure and the concomitant protection provided by the stabilised joint. Similarly, meniscal repairs performed in an ACL deficient knee have a higher failure rate than those in stable or near stable knees w19x. Nevertheless, in low demand patients, acceptable results for isolated meniscal repair in ACL deficient knees have been reported w35x. Repair of more acute tears (i.e. less than 8 weeks old) seem to be associated with better results w19,31x. Medial meniscal repairs, particularly of a posterior horn, are more likely to fail than repair of the lateral meniscus w34x. The more extensive and complex tears are more likely to fail and this occurs most frequently within the first 6 months w31x. 11. Complications As with any surgical procedure, all techniques of meniscal repair carry the risk of complications. These may be general such as superficial and deep infection, deep vein thrombosis, arthrofibrosis and complex regional pain syndromes. Injuries to the common peroneal nerve laterally, the saphenous nerve medially and the popliteal arteries posteriorly, are of greatest concern. Fortunately, major complications are very rare w36x. Nevertheless, some authors recommend a wider exposure to ensure adequate protection of the neurovascular structures with a potential reduction in serious complications w22x. Generally, we have not found this necessary. In this series there have been three significant complications. Early in the series, there were two cases of septic arthritis both treated successfully by early arthroscopic washout and excision of the meniscus fragment and the suture material. One of these patients returned to International level Rugby League football. As a consequence, we have ceased using braided sutures for this technique and have seen no further infections in the last 10 years. There has been one case of peroneal nerve neuropraxia, which resolved completely by 6 weeks post-operatively.
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12. Post-operative rehabilitation The optimum post-operative management protocol for isolated meniscal repairs continues to develop and still remains controversial. Fundamentally, the aim is to protect the meniscus while healing progresses and then perform a phased return to activity while maturation of the scar occurs, so permitting more vigorous activity. Some surgeons are more conservative and others are more aggressive in their post-operative management. Our approach appears to be in the ‘middle ground’. Our typical routine for isolated repairs is to maintain the knee in a Velcro-type splint for 3–4 weeks. During this time simple isometric quadriceps exercises and early range of motion are performed. For longitudinal tears, weight bearing per se in the extended position may, however, not be a significant factor, as it will, tend to force the meniscal fragments together. Nevertheless, patients are usually kept touch weight bearing with crutches for 2 weeks before progressing to partial and then protected weight bearing over the next 4 weeks. The main aim during this time is to prevent shear stresses from occurring and this typically occurs during weight bearing under load. Range of motion is generally limited to 0–908 for 6 weeks. Deep squats should be avoided for 3 months and deep squats with load, as a muscle strengthening exercise should probably be discouraged from further use. Improvement in quadricepsy hamstring balance along with strength and endurance exercises are encouraged to improve the ‘external’ shock absorbers of the knee. Return to sporting activity will typically be introduced at 12–16 weeks. With meniscal repair undertaken at the time of ACL reconstruction, our standard ACL rehabilitation programme is slowed down by approximately 1 week over the first 6 weeks, so that a brace and partial weightbearing is maintained until 3 weeks rather than the typical 2 weeks for isolated ACL reconstructions. Knee bend beyond 908 is not pushed until 6 weeks. From this point on, our routine ACL rehabilitation programme is followed. The return to more dynamic activities such as running is not introduced until 16 weeks with the introduction of sports specific drills at 5–6 months. Accelerated rehabilitation protocols have been described allowing full weight bearing, no immobilisation and returning to sport and pivoting activities as soon as the patient’s knee is functioning well and inflammation is settled w37x. However, it is unlikely that one schedule will fit all patients. The need to accommodate the nature of the tear, concurrent procedures, such as associated ligament reconstruction, and method of repair used are all likely to have an influence on healing rates.
13. Summary Long-term studies have shown both total and partial menisectomy to be associated with premature degenerative change of the knee. Although treatments of articular surface injury remain in their infancy, proven techniques for repair of meniscal tears are now available. When meniscal salvage is possible, preservation of the menisci is advised, particularly in the setting of anterior cruciate ligament deficiency. The meniscus’ contribution to knee joint stability and the higher healing rates in this setting are emphasised. Arthroscopic surgeons should develop a range of meniscal repair techniques to allow them to address tears of differing complexity and location. Attention to biological and biomechanical factors and the use of various adjuncts to promote healing are likely to permit high healing rates for some tears that have traditionally been felt to be irreparable. We recommend that meniscal repair should be attempted if a good clinical indication for meniscal preservation exists, even if the appearances are not classically favourable. References w1x Fairbank TJ. Knee joint changes after menisectomy. J. Bone Joint Surg. wBrx Part B 1948;30:664 –670. w2x Johnson RJ, Kettlekamp DB, Clark W, et al. Factors affecting late results after menisectomy. J Bone Joint Surg wAmx Part A 1974;56:719 –729. w3x McGinty JB, Guess LF, Marvin RA. Partial or total menisectomy: a comparative analysis. J Bone Joint Surg wAmx Part A 1977;59:763 –766. w4x Northmore-Ball MD, Dandy DJ, Jackson RW. Arthroscopic, open partial and total menisectomy. A comparative study. J Bone Joint Surg wBrx Part B 1983;65:400 –404. w5x Rangger C, Klestil T, Gloetzer W, Kemmler G, Benedetto KP. Osteoarthritis after arthroscopic partial menisectomy. Am J Sports Med 1995;23:240 –244. w6x Aspden RM, Yarker YE, Hukins DWL. Collagen orientations in the meniscus of the knee joint. J Anat 1985;140:371 –380. w7x Ahmed AH, Burke DL. In-vitro measurement of static pressure distribution in synovial joints—part 1: tibial surface of the knee. J Biomech Eng 1983;105:216 –225. w8x Thompson WO, Thaete FL, Fu F, Dye SF. Tibial meniscal dynamics using three-dimensional reconstruction of magnetic resonance images. Am J Sports Med 1991;19:210 –216. w9x Baratz ME, Fu F, Mengato R. Meniscal tears: the effect of menisectomy and of repair on intra-articular contact areas and stresses in the human knee. Am J Sports Med 1986;14:270 – 275. w10x Levy IM, Torzilli PA, Warren RF. The effect of medial menisectomy on the anterior–posterior motion of the knee. J Bone Joint Surg wAmx Part A 1982;64:883 –888. w11x DeHaven KE, Arnoczky SP. Meniscal repair. Part I. Basic science, indications and open repair. J Bone Joint Surg wAmx Part A 1994;76:140 –152. w12x Assimakopoulos AP, Katonis PG, Agapitos MV, Exarchou EI. The innervation of the human meniscus. Clin Orthop 1992;275:232 –236. w13x King D. The healing of semilunar cartilages. J Bone Joint Surg 1936;18:333 –342.
K.T. Boyd, P.T. Myers / The Knee 10 (2003) 1–11 w14x Arnoczky SP, Warren RF. The microvasculature of the meniscus and its response to injury. An experimental study in the dog. Am J Sports Med 1983;11:131 –141. w15x Arnoczky SP, Warren RF. Microvasculature of the human meniscus. Am J Sports Med 1982;10:90 –95. w16x Roeddecker K, Muennich U, Nagelschmidt M. Meniscal healing: a biomechanical study. J Surg Res 1994;56:20 –27. w17x 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. w18x Annandale T. An operation for displaced semilunar cartilage: 1885 wclassical articlex. Clin Orthop 1990;260:3 –5. w19x DeHaven KE, Lohrer WA, Lovelock JE. Long-term results of open meniscal repair. Am J Sports Med 1995;23:524 –530. w20x Rockborn P, Gillquist J. Results of open meniscus repair. Longterm follow-up study with a matched uninjured control group. J Bone Joint Surg wBrx Part B 2000;84:494 –498. w21x DeHaven RE, Black K, Griffiths HJ. Open meniscus repair. Technique and two to nine year results. Am J Sports Med 1989;17:788 –795. w22x Cannon WD, Morgan CD. Meniscal repair. Part II: arthroscopic repair techniques. J Bone Joint Surg wAmx Part A 1994;76:294 – 311. w23x 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. w24x Calder SJ, Myers PT. Broken arrow: a complication of meniscal repair. Arthroscopy 1999;15:651 –652. w25x Rimmer MG, Nawana NS, Keene GCR, Pearcy MJ. Various strengths of different meniscal suturing techniques. Arthroscopy 1995;11:146 –150. w26x Arnoczky SP, Warren RF, Spivak JM. Meniscal repair using an exogenous fibrin clot. An experimental study in dogs. J Bone Joint Surg wAmx Part A 1988;70:1209 –1217.
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w27x Zhang Z, Arnold JA, Williams T, McCann B. Repairs by trephination and suturing of longitudinal injuries in the avascular area of the meniscus in goats. Am J Sports Med 1995;23:35 –41. w28x Farley TE, Howell SM, Love KF, Wolfe RD, Neumann CH. Meniscal tears: MR and arthrographic findings after arthroscopic repair. Radiology 1991;180:517 –522. w29x Barrett GR, Field MH, Treacy S, Ruff CG. Clinical results of meniscus repair in patients 40 years and older. Arthroscopy 1998;14:824 –829. w30x Morgan CD, Wojtys EM, Casscells CD, Casscells SW. Arthroscopic meniscal repair evaluated by second-look arthroscopy. Am J Sports Med 1991;19:632 –637. w31x Eggli S, Wegmuller H, Kosina J, Hucknell C, Jakob RP. Longterm results of arthroscopic meniscal repair. An analysis of isolated tears. Am J Sports Med 1995;23:715 –720. w32x Lucas GL, Dusek JK, Henning CE. Isolated arthroscopic meniscal repair: a long-term outcome study (more than 10 years). Am J Sports Med 1999;27:44 –49. w33x DeHaven KE. Meniscus repair. Am J Sports Med 1999;27:242 –250. w34x 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;28:87 –95. w35x Hanks GA, Gause TM, Handal JA, Kalenak A. Meniscus repair in the anterior cruciate deficient knee. Am J Sports Med 1990;18:606 –613. w36x Small NC. Complications in arthroscopic surgery performed by experienced arthroscopists. Arthroscopy 1988;4:215 –221. w37x Barber FA. Accelerated rehabilitation for meniscus repairs. Arthroscopy 1994;10:206 –210.