A Case of Bilateral Permanent Subluxation of the Lateral Meniscus

Abstract

We report a case of bilateral, permanent subluxation of the lateral meniscus. To our knowledge, the present case is the first reported description of bilateral irreducible anterior dislocation of the posterior segment of the lateral meniscus. This disorder is characterized by a flipped meniscus sign of the lateral meniscus on sagittal magnetic resonance images of the knee joint, with no history of trauma or locking symptoms. A detailed examination of serial magnetic resonance images of the lateral meniscus can help differentiate this condition from malformation of the lateral meniscus, that is, a double-layered meniscus. We recommend two-stage treatment for this disorder. First, the knee joint is kept in straight position for 3 weeks after the lateral meniscus is reduced to the normal position. Second, if subluxation of the lateral meniscus recurs, meniscocapsular suture is then performed. Although subluxation of the lateral meniscus without locking symptoms is rare, it is important to be familiar with this condition to diagnose and treat it correctly.

Permanent Subluxation of the Lateral Meniscus in a 10-year-old Boy: A Case Report with Short Literature Review

“…The findings in our patient resemble a case of PSLM by Suganuma et al [ 9 ] in a 37-year-old female. They reported that she had no history of trauma or locking symptoms.…”

“…Her right knee which was more symptomatic had an osteochondral defect of 15 × 20 mm on the lateral femoral condyle. Suganuma et al [ 9 ] stated that PSLM appeared to be related to both congenital and environmental factors, as the dislocated meniscus needs to be adhered to the surrounding tissue. However, as evident in our case, there was no adhesion between the meniscus and the intercondylar space.…”

“…Sunguanuma et al [ 9 ] did not perform any intervention for PSLM as the patient did not consent. Had she consented, they had a two-staged plan ready.…”

“…Subluxations of the lateral meniscus can be recurrent or permanent, always present with episodes of locking [ 8 ]. Recurrent subluxation of the lateral meniscus (RSLM) is characterized by the ability of the posterior segment of the lateral meniscus to displace anteriorly only during episodes, whereas in permanent subluxation of the lateral meniscus (PSLM), the posterior segment stays displaced anteriorly [ 8 , 9 ]. PSLM is so rare that it has only been reported once [ 9 ].…”