An unusual case of patella dislocation.

Correspondence to: Dr Parfitt. A 9 year old boy presented to the accident and emergency department with a painful, tender swollen right knee. He had fallen 4 feet from a wall and struck his knee on the edge of a kerb. On examination the knee was held in a 45 degrees of fixed flexion. A 10 cm horizontal laceration extending to deep fascia was evident. Radiography (see fig 1) revealed the patella to be standing horizontally in the knee joint itself. He was taken to theatre and the wound cleansed and explored. A medial arthrotomy was performed which showed the quadriceps tendon peeled off the upper half of the patella. Knee ligaments were intact. Reduction was easily achieved wound closure effected and the limb immobilised in a cast. The child made a full functional recovery Intra-articular dislocation of the patella is extremely rare.' Most commonly a sporting injury in young males, it should be manipulated under general anaesthetic. An attempt may then be made at closed reduction (with knee flexion to 90 degrees and pressure from below on the patella), though usually open reduction is required.2 The extensor mechanism in these injuries is usually intact and the taut quadriceps pulls the patella into the intercondylar notch.