Spontaneous non-traumatic dislocation of the knee.

Ligamentous injuries of the knee occur during sports and where there is extensive injury associated with subluxation or dislocation. We present a case of an obese female who sustained spontaneous non-traumatic posterior knee dislocation when she caught her foot while rising from the sitting down position. There was associated peroneal nerve injury but an angiogram confirmed no vascular compromise. Surgical ligamentous reconstruction was undertaken.