The authors report a case of repetitive locking knee caused by a subluxation of the posterior horn of a normal lateral meniscus. The posterior horn was sutured to the posterior knee capsule and the athlete resumed complete sports activity 4months after the surger

Borens, Olivier

Djahangiri, Ali

Garofalo, Raffaele

Kombot, Cyril

Mouhsine, Elyazid

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IntroductionSubluxation or dislocation of an intact lateral meniscusis a very rare and controversial cause of pain and lockingknee [2, 4].In literature, the diagnosis and treatment [3], clinicalsigniﬁcance and natural history [7] of symptomatic dis-location of anterior horn of medial meniscus, is welldescribed.On the other hand, to date, we have found only threepapers discussing lateral meniscal subluxation [2, 5, 9],and two of these [5, 9] report on arthroscopic ﬁndings.We report a case of repetitive knee locking syndromein a young soccer player, caused by a subluxating pos-terior horn of a normal lateral meniscus.Case reportA 19-year-old footballer experienced his ﬁfth episode ofright knee pain and locking, during a stretching sessionbefore practice.He reported that during the preceding four times thatthe problem had occurred, over a period of 2 year, hehad felt excruciating pain and a locking episode of hisknee followed by an early and spontaneous resolution.Every time, the episode occurred during sporting activityin an almost full ﬂexion of the knee. No history oftrauma was present.During the most recent, ﬁfth episode, the knee re-mained locked at 90 of ﬂexion and a spontaneousunlocking was impossible, leading to the admission ofthe patient to our institution.An accurate knee examination was diﬃcult becauseof pain. After 2 h from onset of symptoms, the kneepresented an extension lag of 30. Anterior-posteriorand lateral radiographs were judged normal. Skintraction was applied over night. The following day theknee was unlocked, less painful and the sportsmedicine team examined the patient. Clinical exami-nation was within normal limits: no swelling of theknee, no signs of instability were present and McMurray’s and Apley’s compression/distraction testwere negative. During the manoeuvre of knee hyper-ﬂexion the patient demonstrated an ‘‘apprehensiontest’’, he felt an imminent sensation of locking knee.After discussion with the patient a knee arthroscopywas carried out.Raﬀaele GarofaloCyril KombotOlivier BorensAli DjahangiriElyazid MouhsineLocking knee caused by subluxationof the posterior horn of thelateral meniscusReceived: 20 February 2004Accepted: 17 August 2004Published online: 11 January 2005 Springer-Verlag 2005Abstract The authors report a caseof repetitive locking knee caused bya subluxation of the posterior hornof a normal lateral meniscus. Theposterior horn was sutured to theposterior knee capsule and the ath-lete resumed complete sports activity4 months after the surgery.Keywords Lateral meniscus ÆKnee Æ Locking Æ SubluxationDOI 10.1007/s00167-004-0581-xKnee Surg Sports Traumatol Arthrosc(2005) 13: 569–571 KNEER. Garofalo Æ C. Kombot Æ O. BorensA. Djahangiri Æ E. Mouhsine (&)Department of Orthopaedic Surgery andTraumatology, University Hospital,OTR-BH 14, CHUV, 1011 Lausanne,SwitzerlandE-mail: Elyazid.Mouhsine@hospvd.chTel.: +41-21-3142791Fax: +41-21-3142800During arthroscopy, we noted a normal femoro-patellar joint, no presence of a plica, a normal medialmeniscus and cruciate ligaments. The lateral meniscusappeared to be normal in size and shape (Fig. 1). Duringﬂexion however, we noted a hypermobility of the lateralmeniscus with the posterior horn displacing anteriorly.This hypermobility was better proven using a hookprobe (Fig. 2). At this point, the posterior capsule wasdebrided and an inside-out arthroscopic suture, stabil-ising the posterior horn of the lateral meniscus to thepostero-lateral knee capsule was performed. A prolene2/0 suture was used, which was passed in a ﬁgure of eightpattern as described by Jordan [6]. No further ﬁxation ofmeniscus to the popliteus tendon was performed toreinforce the repair, because after the suture was per-formed, the stability of the meniscus was restored.Post-operatively the knee was immobilised for3 weeks with a brace in extension. Weight bearing astolerated was allowed. After 3 weeks, the brace wasremoved three times each day and an active assistedmobilisation of the knee was started. At 4 weeks, theimmobilisation was completely discontinued. At6 weeks, the patient presented an active range of kneemotion of 140/0/0 and no imminent sensation of lockingwas found at clinical examination. At 3 months, low-impact sports activities were allowed and complete re-turn to sport was possible at 4 months.At 1 year of follow-up, the patient was satisﬁed of hislevel of sports activities and neither complaints nor otherepisodes of locking knee were experienced.DiscussionIn contrast to a locked knee caused by the anterior hornof the medial meniscus, which seems to be a well-dis-cussed topic in the literature [1, 3, 8], the locked painfulknee caused by a hypermobile lateral meniscus is rarelyreported [2, 5, 9].Moreover, it seems that the dislocating horn of themedial meniscus is a normal anatomic variant with littleclinical signiﬁcance and that the need for surgical man-agement is questionable [8]. In the case of an hyper-mobile, subluxating posterior horn of the lateralmeniscus, surgical ﬁxation is indicated as reported bysome authors [5, 9] and conﬁrmed by our case. Diﬀeringfrom a precedent report [5], and similar to another [9],there was no true inciting trauma before episodes oflocking occurred in our case. Our patient, in fact, com-plained of pain and locking of the knee after hyper-ﬂexion (i.e. stretching of extensor muscles of the thigh).During arthroscopic evaluation no other anomalies ofthe knee were observed, which diﬀers from an MRIstudy [2], where a subluxating meniscus was alwaysassociated with other internal derangement of knee.From an anatomic point of view the posterior horn ofthe lateral meniscus attaches to the tibia behind the in-tercondylar eminence. The Wrisberg-type discoidmeniscus [10] presents a deﬁcient attachment of themeniscotibial ligaments, having only the menisco-femo-ral ligament of Wrisberg as posterior stabiliser, leadingto a potential unstable meniscus and therefore the causeof knee locking.. To date there is no clear explication fora locked knee resulting from a non-discoid variant oflateral meniscus, as in our case and other rare cases [2,5]. The posterior horn of the lateral meniscus might besusceptible to subluxation, because it has only a looseattachment to the capsule, which is interrupted by thepopliteus tendon [7]. Cohn [4] described the anatomy ofthe popliteus hiatus, showing that the superior border isrepresented by the posterior superior popliteomenisclefascicle and the inferior border by the anterior inferiorpopliteomeniscle fascicle. The occurrence and consis-tency of fascicular attachments between the lateralmeniscus and popliteus tendon are still debated [9]. Si-monian et al. [9] reported three cases of lateral meniscussubluxation and they identiﬁed disruption of the fas-Fig. 1 Normal size and shape appearance of the lateral meniscusFig. 2 Hypermobility with subluxation of the lateral meniscusduring forced ﬂexion570cicular attachments between the popliteus tendon andlateral meniscus as the cause of meniscus instability.These ﬁndings were conﬁrmed by MRI study. In ourcase an MRI study was not performed, to allow an earlymanagement of the lesion. On the other hand, in thestudy of Simonian [9], the MR studies were at ﬁrstconsidered normal, showing the diﬃculty in revealingcertain pathological ﬁndings overall, when the imagesare performed with the meniscus in the reduced position.Moreover, because the three cases represented diﬀerentclinical scenarios, the author [9] did not make a con-clusive statement. So it is possible that other types oflesion can also explain this subluxation.In fact, it may be that the subluxating posterior hornrepresents a further congenital variant or an anomaly ofthe lateral meniscus. In certain subjects, the lateralmeniscus, although not discoid, can be present withloose menisco-tibial ligaments, so that minimal traumacan result in complete failure of the ligaments and leadto subluxation. All these hypotheses should be con-ﬁrmed by prospective studies, which may be diﬃcult toperform, because the rarity of this lesion. Moreover, itwill not bring many advantages to the treatment,because all the reported cases are well on repairing theposterior horn of the lateral meniscus to the posteriorcapsule.About the diagnosis of this lesion, we think as re-ported by Simonian [9] that an important role is playedby clinical history and clinical examination. The MRIstudy can be useful to eliminate other diagnosis, and itshould be correlated to the clinical presentation; other-wise, an overdiagnosis of this injury can occur. Even-tually, it should be performed in a locked position of theknee [5] to obtain more information.Another important point is the resumption of sportsactivity. On the basis of clinical examination and sup-posing that the time for a biological scar formation be-tween the posterior horn of the meniscus and the capsuleis at least 3 months, we allowed a complete resumptionof sports activities at 4 months after surgery. Our resultat follow-up was good and showed no sign of recurringsubluxation.It was not possible to compare this data, asthe relevant literature was lacking.In conclusion, although not much reported, sublux-ation of the posterior horn of an intact lateral meniscuscan be the only cause of a locking knee.References1. Boucher HH (1964) Anterior marginalseparation of the meniscus of the knee. JBone Joint Surg Br 46:539–5412. Breitenseher MJ, Trattnig S, DobrockyI et al (1997) MR imaging of meniscalsubluxation in the knee. Acta Radiol38:876–8793. Clancy WG, Keene JS, Goletz TH(1984) Symptomatic dislocation of theanterior horn of the medial meniscus.Am J Sports Med 12:57–644. Cohn AK, Mains DB (1979) Poplitealhiatus of the lateral meniscus. Anatomyand measurement at dissection of 10specimens. Am J Sports Med 7:221–2265. George M, Wall EJ (2003) Locked kneecaused by meniscal subluxation: mag-netic resonance imaging and arthro-scopic veriﬁcation. Arthroscopy 19:885–8886. Jordan MR (2000) Lateral meniscalvariants. Operative Tech Orthop10:234–2447. Mc Murray TP (1949) The semilunarcartilages. Br J Surg 29:407–4148. Pinar H, Akseki D, Bozkurt M, Ka-raoglan O (1998) Dislocating anteriorhorn of the medial meniscus. Arthros-copy 14:246–2499. Simonian PT, Sussmann PS, Wick-iewicz TL et al (1997) Popliteomeniscalfasciculi and the unstable lateralmeniscus: clinical correlation and mag-netic resonance diagnosis. Arthroscopy13:590–59610. Watanabe M, Takeda S, Ikeuchi H(eds) (1979) Atlas of arthroscopy 3rdedn. Igaku-Shoin, Tokyo, pp 75–130571

Locking knee caused by subluxation of the posterior horn of the lateral meniscus

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Locking knee caused by subluxation of the posterior horn of the lateral meniscus

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