Microscopic examination of a naturally occurring epiphyseal plate fracture.

We had the opportunity to examine a naturally occurring Salter-Harris Type I fracture in the distal tibia of a 9-year-old boy. The injury was simultaneous with traumatic amputation of the extremity a few centimeters distal to the knee. The epiphyseal plate was examined microscopically, and the plane of cleavage was found not to be uniform, but to involve the zones of resting, proliferating, hypertrophying, and provisionally calcified cartilage cells. We hope by demonstrating the inconsistency of the cleavage plane in this case to assist in understanding the complexity of physeal fractures and the unpredictable results that occasionally occur.