Meniscus injuries Where do we stand - PDF document

Meniscus injuries: Where do we stand? BR Gelbart Orthopaedic Surgeon/Knee Surgery Fellow, Honorary consultant, Charlotte Maxeke Johannesburg Hospital Soft TissueKnee Clinic, Division of Orthopaedic Surgery, University of Witwatersrand, Johannesburg Firer Orthopaedic Surgeon, Netcare Linksfield Clinic, Orange Grove, Johannesburg; Honorary Consultant, Charlotte MaxekeJohannesburg Hospital Soft Tissue Knee Clinic Reprint requests: PO Box 28985 R EVIEW A RTICLE R EVIEW A RTICLE SA O J OURNAL Page 59 Abstract The role of the meniscus in the knee has previously been grossly underestimated. The last 25 years have pro-duced an enormous amount of researchighlights the importance of the meniscus to the function of theknee. The primary role of the meniscus is load bearing in order to decrease the forces on the articular surface ofthe femur and tibia. However,the meniscus also functions as a secondary stabiliser of the knee,providing joint M enisci were once thought to be functionless,vestig-ial remnants in the knee.Just as wbelieve that wecould livtotal meniscectomywaswev 1 shock absorption,stabilisa-tion and load transfer. 2,3 he second is theraneering. Menisci can now be repaired through a varietyof methods and also transplanted and cultured in a lab-oratory.preservation.In the United States of America approximately 1 million 4 common procedure logged during their part II board cer-tification exam was an arthroscopic meniscal debride- 5 This review aims to highlight the current trends in theield. SAOJ Spring 2009 8/7/09 11:41 AM Page 59 Page 60 SA O RTHOPAEDIC J O Spring 2009 R E A RTICLE Anatomy of the menisci The menisci are two wedge-shaped semilunar sections offibrocartilaginous tissue. They are found between thefemoral and tibial surfaces of the knee joint,with onecompartment. The medial meniscus has a wider radius ofcurvature than the lateral. They both attach to the tibia attheir anterior and posterior horns and are also attached to thesurrounding tissue. The medial meniscus is attached to thedeep portion of the medial collateral ligament. The lateralmeniscus is attached to the femur by the meniscofemoralligaments. Both menisci are attached to one another anteri-orly by the transverse intermeniscal ligament.These attachments are important as they maintain theposition of the menisci,but are also sites which predis-oscopically,the menisci are composed of cellularcomponents embedded in an extracellular matrix.It is unknown whether meniscal cells are chondrocytesor fibroblasts. Since they contain elements of both thesecells they have been termed ÔfibrochondrocytesÕ. 6 cells are responsible for many functions,one of which isto synthesise collagen which decreases with age.The extracellular matrix of the meniscus comprises fourcomponents:water (72%),fibrillar components (collagen ¥Collagen type I is the most predominant fibrillarcomponent within the tissue,but smaller amounts ofcollagen type II,III,V,and VI have also been found.Collagen consists of three layers 7,8 ( Figure 1 ): ¥ icial layer Ð thin layer of randomly orientedfibres ¥ Lamellar layer Ð inside the superficial layer.Consists of randomly oriented fibres except at theperiphery and anterior and posterior horns. In thesees are or ¥ The deep zone consists of circumferentially orient-ed fibres with a few radially oriented fibres calledtie fibres ¥Proteoglycans are responsible for hydration andtherefore the compressive properties of the meniscus. ¥Adhesion glycoproteins are responsible for bindingwith other matrix molecules and cells. blood supply medial and lateral genicular arteries. These form the per-imeniscal capillary plexus at the peripheral attac

hments tothe joint capsule. The outer one third of the adult menis-cus is vascularised and is also surrounded by synovial tis-sue,while the inner third is avascular. The middle third isa watershed zone. The vascularisation is important to con-sider when discussing management options.Interestingly the infantÕs meniscus is fully vascularised.being divided into three zones,depending on the vascularThe red-on-red zone refers to the outer third,the red-on-the inner third. While tears found within the red zones arelikely to heal,those in the white zones are avascular andhave no potential to heal. 9 Biomechanics of the meniscus 8,10 sion,but the menisci also play a secondary role in stabil-isation of the knee and joint lubrication.The arrangement of the collagen fibres in a circumfer-ential manner with radial ties converts the compressiveces to radial fthe longitudinal collagen fibres. These are known asÔhoop stressesÕand the circumferential collagen fibres areideally aligned to decrease these forces ( Figure 2 ). Figure 1: The arrangement of collagen fibrils 8 ) Figure 2: The biomechanics of the meniscus.arrow) to hoop stresses i.e. radial force (blackarrow) and this acts as a tension force (dottedarrow) (reproduced with permission from 10 ) collagen fibresRandom collagen SAOJ Spring 2009 8/6/09 5:18 PM Page 60 R EVIEW A RTICLE SA O RTHOPAEDIC J OURNAL Page 61 circumferential collagen fibres and defunctions themeniscus,whereas longitudinal tears will have the twosides compressed together by these forces.The shape of the menisci with a large radius of curvatureat the horns and a smaller radius of curvature at the cen-e,allows the meniscus to reduce cartilage stresses effec-vely throughout extension and flexion respectively. 3 The menisci transmit approximately 50% of the bodyweight in extension and up to 85-90% in flexion. 11 he menisci also stabilise the knee. Although the menis-ci are mobile structures they are tethered at certain points.It is well known that an anterior cruciate ligament (ACL)deficient knee with an intact meniscus will be more stablethan an ACL deficient knee without an intact meniscus.However,the meniscus will not provide enough restraintto substitute for the ligament.The extensive nerve supply in the menisci includesmechanoreceptors and free nerve endings in the peripher-al two-thirds,with the highest concentration in the poste- 12 This suggests that the menisci may have antant role in proprioception and protective reflexes.The improved congruity provided for by the meniscimay help joint lubrication and cartilage nutrition. Classification of meniscal tears 13 Tears of the meniscus can be divided in to five main types: Longitudinal tears he meniscus splits due to a shearing force. This splitoccurs between collagen fibrils. If these occur in theperipheral zone they are usually amenable to repair. Aitudinal tear may comprise part of a bucket han-dle tear,where the inner portion of the meniscus folds Figures 3 and 4 ).2. Horizontal tears Ð most commonly in a demeniscus. Delamination between the different layers ofen occurs resulting in sefrom the inferior surface of the meniscus. These usuallyextend to the inner margin of the meniscus,i.e. the avas-and as such are not amenale to repair. Radial tears Ð run from the meniscus margin towardsthe periphery. The longitudinal collagen fibres are dis-upted and as such the meniscus becomes defunc-tioned. This injury is indicative of a high energy injuryor a degenerate meniscus ( Figure 5 ).4. Flap tear Ð similar to a radial tear in that it extendsacross the inner margin,but the tear runs obliquelyacross the meniscus. These may also result in transec-tion

of longitudinal collagen fibres indicative of a highenergy injury or degeneration. The flap may have ay to fold into the joint causing mec Degenerative/complex tears Ð the majority of degen-erate menisci have marked derangement of the colla-gen architecture. This results in multiplanar tears,which are generally not repairable. Clinical evaluation Symptoms A careful history is important when assessing for possiblemeniscal damage. Most patients can recall the mechanismof injury,which is usually a loading,twisting action of theknee with sudden onset pain. Figure 3a: Top: unstable longitudinal tear ofFigure 3b: Bottom: stable rim post debride- ab Figure 4b and 4c: Collagen implant insertedinto defect and sutured in situ. Combination bc Figure 4a: 19-yr-old male previous partialmeniscectomy for irreparable tear in menis- SAOJ Spring 2009 8/6/09 5:18 PM Page 61 Page 62 SA O RTHOPAEDIC J O Spring 2009 R E A RTICLE A knee that swells immediately (haemarthrosis) mayindicate a tear in the peripheral vascular portion of themeniscus. However,in this situation it is important todral fracture,disruption of joint capsule or ACL rupture. More commonly a tear in the central,less vascular,por-ter.atients who present with more chronic injuries maycomplain about recurrent effusions.king of the knee,i.e. an inability to extend the kneeafter rising from a crouched position,has been shown tobe present in 81% of patients with a bucket handle tear. 14 ain is usually localised to the affected joint line. Sometivy. Signs A subtle sign of chronic pathology is quadriceps muscletrophy.The presence of an effusion particularly in a knee with aonic problem is suggestive of intra-articular pathology.Patellofemoral disorders often produce symptoms ofclicking and may refer pain to the medial joint line. It istant to examine this joint and to attempt to repro-duce the pain or clicking that the patient may be experi-encing,to diffentiate from a meniscal tear.Meniscal injury is suggested by the presence of jointline tenderness,particularly the posteromedial or postero-al joint line.This pain is usually reproduced on deep flexion.Knee stability must be assessed in every patient suspectedof having a meniscal injury.Hip pathology should also be excluded.A number of eponymous provocative tests have been ¥ApleyÕs grind test Ð With the patient lying prone,theknee is flexed to 90¡. A compression rotation force isplaced on the knee through the heel. Pain suggests ameniscal tear. ¥McMurrayÕs test Ð The patient lies supine with theknee fully flexed. One hand is placed on the knee,theother under the heel. The knee is flexed and thenstraightened by the examiner. While straightening,a val-gus force and external rotation of the heel will catch theposterolateral meniscus. Pain or clicking is positive fora tear. The manoeuvre is then repeated from hyperflex-ion using varus force and internal rotation of the heel, ¥Thessaly test heir hands are supported in front of them by the exam-iner. The patient bends the knee 5¡then twists the kneeinternally then externally three times in each direction.ted at 20¡flexion. The normal side ised by the side of the suspected injury. 15 Pain is the positive sign.It must be remembered that in a small percentage of cases,the knee to which the pathology occurs,i.e. posteromedialtears can present with lateral/posterolateral symptoms. Imaging the meniscus X-ray y to exclude bony lesions. Occasionallychondrocalcinosis of the meniscus can be seen. This maybe a clue to the presence of a degative tear. Contrast arthrography thrography was used to assess for internalement in the knee. It was a useful adjunct butsymptomatic pati

ents were recommended for arthroscopyaphy findings. 16 Ultrasound elatively cheap,non-invasive investigation. Sincethe value of this investigation is the dynamic changes notedeen,ultrasound is very operator-dependent. This isiable figures produced in the literature.Ultrasound for meniscal injuries has been shown to have avity of 60Ð100%and specificity of 21Ð100%. 17-20 Higher sensitivity and specificity are acved with moreadvanced probes. Of concern is the high number of falsees (low specificity) that are seen. Although practisedfrequently by many radiology units,it should be Ôcon-demnedÕto research as it has no clinical relevance. Figure 5: A complete radial tear of the poste-rior horn of the lateral meniscus in an ACL Remember that in a small percentage of cases,theof the knee to which the pathology occurs SAOJ Spring 2009 8/6/09 5:18 PM Page 62 R EVIEW A RTICLE SA O RTHOPAEDIC J OURNAL Page 63 Computer tomography (CT scan) CT scanning as been described for meniscus injuries 21 butthe poor soft tissue definition relative to MRI make thisinvestigation a poor first choice. Magnetic resonance imaging (MRI) identification of meniscal injuries. 22 Some reports haveshown that MRI is more sensitive than clinical examina- 23-25 However,as with most investigations,this dependson the experience of the radiologist. It seems that studieswith more patients tend to produce better sensitivities andspecificities. MRI for medial meniscus tears shows a sensi-tivity between 86% and 96% 14 and a specificity of 22 MRI for the diagnosis of lateral meniscus tears has a lowersensitivity (68Ð86%),but higher specificity (92Ð98% 22 While MRI yields a low false positive rate for lateral menis-cus tears,the false negative rate of 14-32% must be consid-ed in the absence of a tear on MRI.Due to tightly bound protons,short TE sequences are mostThere are two criteria that must be fulfilled on MRI inder to make the diagnosis of a meniscal tearThe first iscus that unequivocally contacts the articular surface of themeniscus. The second is an abnormal meniscal shape in theabsence of previous surgery. The presence of one of theabove has shown that a meniscal tear will be found 90% ofthe time at arthroscopy. 22,26 y useful to exclude other causes of kneepain in the absence of a meniscus tear. These conditionslude infection,tumour,avascular necrosis of the femoralarticular damage or bone oedema (transient osteo- Arthroscopy It is not recommended that arthroscopy should be used as aninvestigative modality. However,when performingoscopy it is important to accurately assess the meniscifor tears. This is achieved by ensuring proper visualisationPeripheral longitudinal tears are easily missed if not probed. Management The key role of the meniscus in the function of the kneeand accelerated degenerative changes seen in a meniscus-deficient knee have led us to focus on meniscus preserva-tion. As early as 1948 Fairbank showed that total menis-cectomy resulted in accelerated radiological change in the 27 This has improved somewhat,with the advent ofpartial meniscectomy. 28 The doyen of partial meniscectomy (through a miniarthrotomy before the days of arthroscopy) was a SouthAfrican surgeon,Dr Clive Noble,in the 1960s and 1970s.There are no randomised controlled trials to show thatarthroscopic meniscal repair has any long-term benefit interms of joint preservation. The good results seen to 10,29 however,suggest that this may decrease the inci-dence of early degenerative changes.so clear. Experimental animal studies have shown thatmeniscal tears can result in chondropathy and osteoarthri- 30,31 Clinical studies though are unable to prove whathappens fir

st Ð the meniscus damage or the articular car- 3 A recent study by Christoforakis et al valuated 497 consecutive knee arthroscopies on patients 36 They found that the mean age ofpatients with complex and horizontal tears was 44.8 yearscompared with 33.6 yrs for the other types of tears. Thesecomplex and horizontal tears were also associated with astatistically increased chance of having Outerbridge 37 grade III or IV articular cartilage damage. Furthermore,the complex and horizontal meniscal tears were morelikely to be associated with more than one site of articu-lar damage than the other tear types. Again this does notwer what came first:the meniscus tear or the articulardegeneration. Interestingly,in their study,81% of thecohort had at least one site of articular cartilage damage.This means that even simple tears in young patients mayOur approach is to actively search for a tear in youngerpatients with clinical and radiological investigationssuspected,the patient is advised to undergo arthroscopyand meniscus preservation surgery.In patients who are suspected of having a degenerativetear,Ômiddle-aged meniscusÕ,the option ofnon-operative treatment is employed. This allows theopportunity of settling the knee without surgery. It is welldocumented that debridement of a degenerate meniscusmay not always result in long-term relief. 38 Non-operative Small peripheral tears in young patients can be managed. The difficulty is to decide withoutarthroscopy whether the tear is stable or not. Weiss et al retrospectively reviewed 3612 arthroscopic proceduresor meniscal lesions. Ty identified 80 (2.2%) meniscaltears that were deemed to be stable. These were not treat-ed. Six patients returned for repeat arthroscopy due tomeniscal symptoms. The authors recommended that sta-ble vertical tears at the periphery have increased potential 34 Physiotherapy Ð This has been shown to be beneficial topatients with degenerative meniscal tears. A recently pub-lished randomised control trial followdegenerative meniscal tears. Patients who underwent sur-gical debridement in combination with physiotherapy didnot show an improved outcome compared to those whoreceived physiotherapy alone. 39 SAOJ Spring 2009 8/6/09 5:18 PM Page 63 Page 64 SA O RTHOPAEDIC J O Spring 2009 R E A RTICLE Corticosteroids Ð Along with physiotherapy,somepatients with degenerative meniscal tears improve after asingle corticosteroid injection into the knee. This is ourfirst-line treatment for a degenerative meniscus,in theabsence of definitive locking symptoms Operative management Total meniscectomy his was the treatment of choice for meniscal lesions until 10 However,since then arthroscopic techniquesmeniscus have led to a shift towards preservation of menis-cal tissue. This form of treatment is seldom practised nowa- Open repair This was popularised by De Haven 40 and was one of theearly means of repairing meniscal tears. This is nowalmost always reserved for fixation of the meniscus ast of the management of tibial plateau fractures or aspart of a multiligament reconstruction,e.g. a posterolater-al corner or midsubstance medial collateral ligament. It is only possible on the very peripheral tears. Arthroscopic repair Meniscal rasping Occasionally small,stable peripheral tears of the meniscuse seen at arthroscopy ( Figure 6 ). Often these are ctears with fibrous tissue in the gap. The meniscal rasp is thenused to debride the torn edges of the meniscus to stimulateThis is indicated in patients who have a stable,longitudi-nal tear in the vascular zone of the meniscus. In should onlybe performed in the presence of complete ligamentous sta-bility or at the time of cru

ciate ligament reconstruction.ascular zone are notamenable to this form of treatment. Meniscal suturing Tears in the red-red zone (periphery) or red-white zone (upto approximately 5mm from periphery) may be amenableto repair. Traditionally,longitudinal tears have been themost amenable to suturing and healing. A proviso for goodknee doom the repair to failure. However,a stable knee,with normal kinematics,will not place unnecessary shearforce onto the repair. In fact,controlled weight bearingThis hoop stress compresses the margins of the tear togeth-er. This may assist healing.Recently reports have emerged about positive results with 10 These are devastat-longitudinal fibres. Results of the repair are not reported inany randomised controlled trials,but case reports seem pos-itive. Post-operatively these repairs should be protected byLoading of the knee will place the repair under tension.ascular zone are at risk for failing.Meniscal repair in conjunction with ACL reconstructionhas consistently shown better healing rates than in the ACL 41 e two fle kneeÕs meniscus may tear because its quality isinferior,whereas the ACL injured meniscus fails because ofsignificant forces.Secondly,in reconstructing the ACL a large haemarthrosisusually occurs and this may stimulate meniscal healing.The late Chuck Henning used to advocate the introduc-tion of blood clot to assist meniscal repair. Techniques Numerous techniques have been described for meniscalrepair. They are based on the technique of passing the Outside in This was the first arthroscopic technique used but is nowthe least common of the methods used. It involves passinga needle from outside the joint,through the meniscus andthen passing a suture through the needle. The suture isieved and knot tied,ideally outside the joint. his technique is primarily used for anterior horn tears. Inside out (Figure 4c) choice. Zone-specific cannulae have been designed allow-ing the surgeon to arthroscopically pass a long straightneedle directly to the injured portion of the meniscus. Thesutures are retrieved under direct vision through a medi-rovascular structures particularly with posterolateralrepairs. These need to be protected by a suitable instru-ment,e.g. a tablespoon. Figure 6a (left): stable longitudinal tear of theFigure 6b (right): ACL deficient knee ab The Ôinside outÕ technique is still the gold standardand remains our method of choice SAOJ Spring 2009 8/6/09 5:18 PM Page 64 R EVIEW A RTICLE SA O RTHOPAEDIC J OURNAL Page 65 All inside (Figure 4b) Numerous all inside techniques have been described,suchrepair devices including meniscal darts,arrows staples andscrews. There have been many reported complications withthese devices including transient synovitis,inflammatoryreaction,cyst formation,device failure,device migrationand chondral damage. For these reasons these bioab-sorbable meniscal implants are generally out of favour. 41 addition biomechanical studies have shown that thesedevices are initially equivalent to suturing techniques; how-ever they are prone to losing strength over time. Fas-T-Fix (Smith and Nephew),Meniscal cinch (Arthrex)and RapidLoc (Mitek) all have good short term results,withmeniscal healing between 80-91% at two-year follow-up. 41 Rehabilitation bilitation protocols vary from centre to centre anddepend on the type of procedure and tear morphology.However,the principle of limited weight bearing and avoid-ance of flexion greater than 90¡should be adhered to for thefirst four to six weeks. Thereafter,a gradual increase inactivity can be allowed. Squatting should be avoided forapproximately five months. 41 Arthroscopic partial meniscectomy (Figure

3b) Irreparable tears of the meniscus,either due to zone ofinjury or complexity of the tear,are best treated by thismethod. Practically,the vast majority of meniscal tears aremanaged this way. The principle is to debride the loose non-cus. This aims to decrease the number of fragments ofarticular cartilage. These loose fragments may also be aResults in a cohort of patients followed up between fiveand 11 years post partial medial meniscectomy in stableknees,showed that the majority of patients had an excellentor good outcome. Patients who had Outerbridge grade III orIV articular cartilage damage were more likely to have a 38 It is for this reason that one should takecare not to automatically Ôscope and debrideÕall patientswith degenerative meniscus tears. Rehabilitation he post operative rehabilitation protocol following partialy should be patient-oriented. Most patientsrequire crutches and remain non-weight bearing for a fewtively. Thereafter they are allowed to weight. Most patients are crutch-free by ten days.A good physiotherapy programme will probably allow mostn to sport in under six weeks (this maybe longer depending on the underlying articular cartilageThis truncated rehabilitation protocol and earliermanagement option with a professional sportsperson orpatient with limited ability to undergo rehabilitation.Some patients request a partial excision as opposed torepair,when feasible,allowing them to return to theirts and livelihood sooner. This comes at the risk ofveloping arthritis later in life. However,there are nolong-term randomised controlled trials comparing jointstatus post repair versus post partial meniscectomy. Meniscus transplant Meniscus transplantation dates back to 1916,when thefirst attempt was made to replace the meniscus with anautogenous fat tissue interposition graft. 42 different techniques of transplanting the tibial plateauor parts thereof were tried. Milachowski et al first to report on free meniscal transplants. 43 Subsequently many different types of substitutes have 42,44 ¥Total meniscectomy with early arthritis Ð slow pro-¥Loss of anterior cruciate ligament Ð provide stabili-ent or delayed ligament¥Concomitant osteotomy Ð enhance effect and post-¥Prophylactic transplantation Ð avoid consequencesof meniscectomy in young patient due to irrele knee. Meniscal transplant is contrthe presence of grade IV articular cartilage damage or Types of graft Autograft Interposition autografting of the patella tendon, 45 quadriceps tendon, 45 fat pad 46 and perichondral tissue 47 have been attempted. These experiments were mainlyperformed on animals. The quadriceps tendon was theonly graft that made it to clinical application. Although,at relook arthroscopy,the tendon looked like meniscus,it was soft. The patients did not have any significantimprovement in their outcome scores. Based on theselimited studies autograft is not recommended for long- The ideal candidate is younger than 50 years old with a stable knee SAOJ Spring 2009 8/6/09 5:18 PM Page 65 Page 66 SA O RTHOPAEDIC J O Spring 2009 R E A RTICLE Allograft Meniscal allograft would seem to be a potential answer.The process involves finding a suitable donor. Thisinvolves strict monitoring according to the national tissuebank. The donor would need to be screened for infectionsand blood typing. The recipient then needs to be anatom-y matched according to the available meniscus. The recipient should be investigated by following 42 Long leg standing X-rays Ð to assess the alignment of¥Plain X-rays Ð to assess the degree of arthritis andbony landmarks to size the meniscus¥Computerised tomography scan Ð this should ideally¥MRI Ð

provides information on the status of themeniscus,cartilage and ligaments as well as for sizematching.Arthroscopy Ð may give more information on status ofte currently surrounds the best method of graftpreservation. Fresh-frozen provides the best tissue but isthe most immunogenic and carries the highest infectionrisk. It is also difficult to store and is not readily available.ozen meniscus are destroyedut may be stored for longer.Lyophilised or freeze-dried menisci loose all antigensand enzymes,but the ground substance decays. Thisleaves a collagen scaffold for growth of host fibrochon-ocytes. These menisci also decrease in size,changingCryopreservation using glycerol may partially maintainhondrocytes for two to four weeks,but this isxpensive.The menisci can also be secondarily sterilised by tissuebanks using gamma iradiation or ethylene oxide.However,the ethylene oxide may induce secondary syn-ovitis and the gamma sterilisation may weaken the colla-ucture.In South Africa we have menisci available from the twomain tissue banks. All donors are suitably screened forinfection. he menisci are harvested with the tibialplateau and then this is cut to fit the defect size. The spec-imens are fresh fren and irradiated and are freely avail-Due to the variability in different methods of preservingmeniscus tissue,differvarying criteria for implantation,there are no randomisedcontrolled trials assessing outcome. It is also difficult toe diffally,the reported out-comes show an overall failure rate of around 20%. Mostpatients can expect pain relief and an ability to increaseactivity levels. This is supported by midterm studies. 44 Ten-year outcome studies on case series have been report- 48 Despite significant improvement the patients werestill substantially disabled. However,radiographic follow-up did not show advanced degenerative changes. Meniscal prostheses Multiple synthetic materials have been considered to beused as menisci,such as Teflon, 49 Silastic, 42 fibre, 50 Dacron 51 and polyvinyl alcohol hydrogel. 52 of these have proven to be a success and should not beCurrently collagen-based meniscal implants have beenproduced and trials are currently underway ( Figures 4b ). Tissue engineering The complex nature of the cells and the extracellular matrixmakes the meniscus very difficult to engineer. 8 Various stud-ies have given tissue engineers knowledge on how fibro-ytes react to certain growth factors. There stillgrown in vitro and then transplanted into patients. The basis of meniscus engineering is to develop the bestold to allow the cells to grothe right growth factors and culturing conditions then pres-to able to accurately image the graft and assess viability. Conclusion Meniscus injuries comprise a large percentage of thework done by orthopaedic surgeons. Current managementhas moved towards meniscus preservation. Althoughthis has still not become a routinely performed procedureand probably still has a limited role in our environment.We await the outcome of engineered menisci as perhapsthey will be the answer. No benefits of any form have been received from a com-mercial party related directly or indirectly to the subjectof this article. References 1.Macconaill MA. The function of intra-articular fibrocar-ges,with special reference to the knee and inferior J Anat 1932; 66 2.Shrive NG,OÕConnor JJ,Goodfellow JW. Load-bearing Clin Orthop Relat Res Shrive NG,Frank CB,Hart DA. Finite ele-ment analysis of the meniscus:the influence of geometryial properties on its behaviour. Knee 2003; 10 4.Cook JL. The current status of treatment for large menis- Clin Orthop Relat Res 2005;435:88-95. SAOJ Spring 2009 8/6/09 5:18 PM

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