Atraumatic sequential bilateral locking of the knee joints secondary to dislocation of non-discoid lateral menisci without radiological abnormality.

Lateral meniscus dislocation, as a cause of atraumatic knee locking, is often attributed to a discoid meniscus which can be readily diagnosed on MRI. In the absence of radiological abnormality, a dislocated lateral meniscus is a rare occurrence. We present a case of a 14 year old male who presented with atraumatic sequential locking of bilateral knees 6 months apart. Although on both occasions, MRI was normal, arthroscopy demonstrated dislocating lateral menisci that were subsequently surgically stabilised. To date, there have been no reports describing this phenomenon bilaterally in the same patient. A high index of suspicion is needed to evaluate a locked knee in an adolescent in the absence of trauma or a radiological abnormality. Furthermore there is a probability of a similar occurrence in the opposite knee.