Internal derangement of the knee in fibular hemimelia: radiographic and MRI findings.

[trochlear dysplasia]

Fibular hemimelia is a rare bone dysplasia with partial or complete absence of the fibula . There are many associated lower limb deformities .We describe the commonly associated bone and soft tissue abnormalities in the knee joint in a case series of six knees in five patients with fibular hemimelia who underwent both radiographic and MR imaging .In all knees , there was an elongated conjoint tendon of the lateral collateral ligament and biceps femoris . In five out of six knees , there was trochlear dysplasia . In four out of six , there was complete absence of the anterior cruciate ligament . In four out of six , there was an abnormal lateral meniscus (three were hypoplastic and one absent ).These associations in fibular hemimelia , although unpredictable , have relevance in the guidance of further orthopaedic management in this complex condition .