Experimental physeal fracture-separations treated with rigid internal fixation.

Salter-Harris Type-III and Type-IV epiphyseal injuries were created in the distal aspect of the femur in growing rabbits, and the healing process was analyzed both in the absence of any treatment and after treatment with anatomical reduction and fixation with compression with use of a cortical screw. A sham operation was performed on the left knee, to create a control group. Untreated Type-III injuries led to an angular deformity of the femur that became more severe with time. In the group that had an untreated Type-IV injury, a step-off developed on the articular surface and increased with time. Early vascular anastomoses between the epiphysis and the metaphysis preceded the formation of osseous bridges in these lesions. The healing process in the animals that were treated with anatomical reduction and rigid internal fixation occurred without the formation of osseous callus, and no marked abnormalities were discernible in the physis.