MR imaging of meniscal malformations of the knee mimicking displaced bucket-handle tear

Abstract

We report two cases of patients with lateral meniscal malformations of the knee that were found incidentally. Magnetic resonance imaging (MRI) of both cases showed a fragment-like meniscus structure located in the intercondylar notch, very similar to the "fragment in the intercondylar notch sign" observed in displaced bucket-handle tear. Arthroscopic examinations revealed a ring-shaped lateral meniscus in one case, and "flipped-over" lateral meniscus in the other. In the latter, a similar lateral meniscal malformation was observed contralaterally at MR arthrography.

A Case of Bilateral Permanent Subluxation of the Lateral Meniscus

“…To our knowledge, this is the first reported description of permanent subluxation of the lateral menisci. However, there is a previously reported case of bilateral malformation of the lateral menisci, in which the pathological characteristics resemble those of the current case [ 1 ]. The aim of this report is to differentiate permanent subluxation of the lateral meniscus from meniscal malformation, especially the double-layered lateral meniscus [ 2 ], and recommend a treatment for this pathology.…”

“…There is a previously reported case in which the pathological characteristics had a distinct resemblance to the present case. Fujikawa et al reported the case of a 37-year-old man with bilateral lateral meniscal malformation consisting of a duplicated anterior horn and the absence of the lateral portion of the menisci [ 1 ]. They did not think that the condition was caused by a displaced bucket-handle tear, because they could not move the duplicated smooth-surfaced menisci.…”

Symptomatic ring‐shaped medial meniscus

“…Watanabe described three types of lateral discoid meniscus (Watanabe et al, 1979). Most recently, a fourth type, consisting in a ring-shaped meniscus, has also been proposed (Monllau et al, 1998;Arnold et al, 2000;Fujikawa et al, 2002). A ring-shaped meniscus is a variant characterized by a ringshaped morphology with a normal posterior tibial attachment (Monllau et al, 2006).…”

Ressonância magnética na avaliação das variações anatômicas meniscais e da anatomia ligamentar perimeniscal: potenciais causas de erro de interpretação

“…With the exception of discoid meniscus, other meniscal malformations are much less frequent, with an incidence of 0.3% (14) . Such variations are more prevalent in the population of Asian countries, in the lateral meniscus and are frequently asymptomatic (15) .…”

“…Such variations are more prevalent in the population of Asian countries, in the lateral meniscus and are frequently asymptomatic (15) . Such variations include ring-shaped meniscus, both partial or complete meniscal hypoplasias, double-layer meniscus and meniscal insertion abnormalities (14,(16)(17)(18)(19)(20) .…”