The fate of articular cartilage in traumatic dislocation of the hip.

The right hips of 69 five-day-old rabbits were dislocated surgically and left to develop in the dislocated position to determine the nature and timing of changes in the hip. Using the left hips as controls, 15 survivors were killed and studied macroscopically and microscopically at two months of age and 14 at four months of age. It was found that articular cartilage of the acetabulum in the dislocated hips showed fibrous degeneration in about 50% of the two-month-old rabbits cases and in all of the four-month-old rabbits. In the dislocated femoral heads the articular cartilage was normal, and only 25% of the four-month-old animals showed fibrous degeneration.