Osteochondritis dissecans is a form of osteochondrosis limited to the articular epiphysis. In the knee joint, medial femoral condyle is the most commonly affected site. We report a patient with osteochondritis dissecans of the medial femoral condyle associated with anomalous medial and lateral menisci.
A 10-year-old otherwise healthy boy presented with activity-related pain and intermittent swelling of his left knee of 2 months duration. He had no evidence of significant knee trauma. There was no locking, catching, or giving way sensation. He was walking with a slight limp. He could not localize the pain.
On physical examination, both knees had valgus alignment with a femorotibial and Q angles of 9°and 23°, respectively. He had minimal effusion, but a full range of motion with mild medial-sided pain. There was no pain at the joint lines, but moderate tenderness at the anteromedial side. Patellofemoral examination was normal and asymptomatic. Lachman, anterior drawer, pivot shift, Apley and McMurray tests showed negative results. There was no ligamentous instability and no generalized laxity was clinically observed.
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Figure 1: Sagittal proton density-weighted MRIs showing the hypoplasia of the medial meniscus with accompanying osteochondritis dissecans of the medial femoral condyle (A) and partial deficiency of the lateral meniscus (B).
Initial plain radiographs revealed narrow medial tibial plateaus with an increased concavity and osteochondritis dissecans of the medial femoral condyle of the symptomatic knee. Notch width index as measured on tunnel-view radiographs was 0.225 on the left and 0.231 on the right knee. Magnetic resonance imaging (MRI) revealed bucket-handle tear of the medial meniscus and partially deficient lateral meniscus and osteochondritis dissecans at the lateral aspect of medial femoral condyle without any significant bone loss with a nondislocated fragment (Figure 1).
Conservative treatment without weight bearing and physical therapy was discussed with the family, but was rejected depending on the doubt of complete tolerance and adaptation of the child. Arthroscopic surgery was performed under general anesthesia. Examination under general anesthesia was insignificant. Arthroscopically, there was an incomplete separated osteochondral flap with partial discontinuity that was unstable on probing on the lateral aspect of the medial femoral condyle. The medial meniscus was hypoplastic without a body and only the meniscal rim could be seen (Figure 2A). There was a narrow intercondylar notch and a large tibial spine with a narrow tibial plateau. The lateral meniscus had an anomalous vertical insertion of the posterior horn, normal body, but an absent anterior horn (Figure 2B). Anterior cruciate ligament was intact, but looked like a peacocks tail. Subchondral debridement and arthroscopic fixation of the chondral lesion with a 0.8-mm K-wire was performed and weight bearing was restricted. Six weeks after the initial operation, a second-look arthroscopic procedure was performed to remove hardware and to evaluate fragment stability. At the second-look arthroscopy, the chondral lesion was stable and healed with some hypertrophy. There was synovitis due to implant reaction. At 6-month follow-up after physiotherapy, the patient was pain free with minimal subjective symptoms after higher activities. At 4 months, 1 year, and 2-year follow-up, MRI studies were used to evaluate potential healing of the subchondral bone and hypointense image with sclerosis was revealed. At 30-month follow-up, the patient had no limitation in his daily and sports activity. Due to the malalignment of the both knees, MRI of the asymptomatic right knee revealed similar meniscal anomalies.
The most common anatomic variation of the meniscus of the knee is discoid lateral meniscus, and congenital abnormalities of the medial menisci are rare.1 Some of the reports about the anomalies of the medial meniscus include complete absence,2 anomalous insertion,3 discoid variants4 or bone changes5 and hypoplasia.6 Other than discoid lateral meniscus, duplicated or double-layered,7,8 ring-shaped,9,10 hypoplastic,11 or partial deficient12 and with an abnormal band13 malformations have been reported.
Development of the menisci of the human knee joint and the morphological changes have been well-described and no abrupt change in development was observed after birth.14 The menisci develop from an intermediate mesodermal blastema and are fully defined 8 weeks after conception. According to Clark and Ogden, the changes in the configuration of the menisci are due to accommodation of the changes in the femorotibial contact area.14
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Figure 2: Arthroscopy of the left knee. Hypoplastic medial meniscus and osteochondritis dissecans of the medial femoral condyle with a narrow tibial plateau (A). Partial deficiency of the lateral meniscus with an absent anterior horn (B).
The valgus knee and narrow tibial plateau of our patient may be the cause of the abnormal menisci. Nevertheless, Soren15 reported the possibility of persistence at a very early embryogenic cessation stage for the occurrence of a malformed meniscus on the emphasis of his dissections performed on animals.
Fujikawa et al10 reported 2 cases of lateral meniscus malformations mimicking displaced bucket-handle tear on MRI. Magnetic resonance imaging suggested a bucket-handle tear in our patient. Hypoplasia or absence of the medial meniscus should be considered among the differential diagnosis of bucket-handle meniscal tears, especially for patients with no significant trauma to the knee.
The relationship of osteochondritis dissecans and discoid lateral meniscus has been clearly identified.16-20 The accompanying osteochondritis dissecans to the malformation of the menisci of our patient may be explained by the effect of repetitive abnormal stress on weaker osteochondral structures in the growing period that has been assumed by Mitsuoka et al18 for the lateral discoid meniscus cases associated with chondral pathologies.
In a review of the literature on rare meniscal abnormalities, most reports include additional chondral or bony changes suspecting relation to the meniscal malformation. The presented case is similar to the report of Mitsuoka et al,11 but different due to the congenital abnormality of the both menisci. As far as we know, the present case is the first description of congenital anomaly of the both menisci and osteochondritis dissecans together.
Although in most reported cases the symptomatic component of the patients complaint is the associated chondral pathologies and the meniscal or ligamentous abnormalities have been considered as benign conditions, these patients with anomalous knees should be carefully followed-up for the possibility of osteoarthrosis.
The repetitive impingement of the tibial spine may be a contributing factor of osteochondritis dissecans and the hypothesis has been supported by citing the provocative contact forces such as meniscectomy, genu recurvatum, condylar flattening and instability.21 Meniscal or ligamentous anomalies of the knee may be associated with osteochondritis dissecans.
- Jordan MR. Lateral meniscal variants: evaluation and treatment. J Am Acad Orthop Surg. 1996; 4(4):191-200.
- Dejour H, Neyret P, Eberhard P, Walch G. Bilateral congenital absence of the anterior cruciate ligament and the internal menisci of the knee. A case report [in French]. Rev Chir Orthop Reparatrice Appar Mot. 1990; 76(5):329-332.
- Nakajima T, Nabeshima Y, Fujii H, Ozaki A, Muratsu H, Yoshiya S. Symptomatic anomalous insertion of the medial meniscus. Arthroscopy. 2005; 21(5):629.
- Akgun I, Heybeli N, Bagatur E, Karadeniz N. Bilateral discoid medial menisci: an adult patient with symmetrical radial tears in both knees. Arthroscopy. 1998; 14(5):512-517.
- Atay OA, Doral MN, Aydingoz U, Leblebicioglu G. Bilateral discoid medial menisci: association with bone changes in the tibia. Knee Surg Sports Traumatol Arthrosc. 2001; 9(4):217-220.
- Twyman RS, Ferris BD. Congenital hypoplasia of the medial meniscus: a report of two cases. Arthroscopy. 1991; 7(2):148-150.
- Suzuki S, Mita F, Ogishima H. Double-layered lateral meniscus: a newly found anomaly. Arthroscopy. 1991; 7(3):267-271.
- Kim SJ, Lee YT, Choi CH, Kim DW. A partially duplicated discoid lateral meniscus. Arthroscopy. 1998; 14(5):518-521.
- Arnold MP, Van Kampen A. Symptomatic ring-shaped lateral meniscus. Arthroscopy. 2000; 16(8):852-854.
- Fujikawa A, Amma H, Ukegawa Y, Tamura T, Naoi Y. MR imaging of meniscal malformations of the knee mimicking displaced bucket-handle tear. Skeletal Radiol. 2002; 31(5):292-295.
- Mitsuoka T, Horibe S, Hamada M. Osteochondritis dissecans of the medial femoral condyle associated with congenital hypoplasia of the lateral meniscus and anterior cruciate ligament. Arthroscopy. 1998; 14(6):630-633.
- Tetik O, Doral MN, Atay OA, Leblebicioglu G, Turker S. Partial deficiency of the lateral meniscus. Arthroscopy. 2003; 19(5):E42.
- Lee BI, Min KD. Abnormal band of the lateral meniscus of the knee. Arthroscopy. 2000; 16(6):11.
- Clark CR, Ogden JA. Development of the menisci of the human knee joint. Morphological changes and their potential role in childhood meniscal injury. J Bone Joint Surg Am. 1983; 65(4):538-547.
- Soren A. On the etiology of congenital malformation of the meniscus. Arch Orthop Trauma Surg. 1985; 104(5):283-288.
- Irani RN, Karasick D, Karasick S. A possible explanation of the pathogenesis of osteochondritis dissecans. J Pediatr Orthop. 1984; 4(3):358-360.
- Aichroth PM, Patel DV, Marx CL. Congenital discoid lateral meniscus in children. A follow-up study and evolution of management. J Bone Joint Surg Br. 1991; 73(6):932-936.
- Mitsuoka T, Shino K, Hamada M, Horibe S. Osteochondritis dissecans of the lateral femoral condyle of the knee joint. Arthroscopy. 1999; 15(1):20-26.
- Kim YG, Ihn JC, Park SK, Kyung HS. An arthroscopic analysis of lateral meniscal variants and a comparison with MRI findings. Knee Surg Sports Traumatol Arthrosc. 2006; 14(1):20-26.
- Deie M, Ochi M, Sumen Y, et al. Relationship between osteochondritis dissecans of the lateral femoral condyle and lateral menisci types. J Pediatr Orthop. 2006; 26:79-82.
- Crawford DC, Safran MR. Osteochondritis dissecans of the knee. J Am Acad Orthop Surg. 2006; 14(2):90-100.
Drs Beyzadeoglu, Gokce, and Bekler are from the Department of Orthopedics and Traumatology, Yeditepe University, School of Medicine, Istanbul, Turkey.
Drs Beyzadeoglu, Gokce, and Bekler have no relevant financial relationships to disclose.
Correspondence should be addressed to: Tahsin Beyzadeoglu, MD, Ethem Efendi Cad, Erenkoy Konutlari No:19/A-19 Erenkoy, Istanbul 34738, Turkey.