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 pr ocess was analyzed both in the absence of any treatment and after trea tment 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 angu lar deformity of the femur that became more severe with time. In the g roup 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 os seous bridges in these lesions. The healing process in the animals tha t were treated with anatomical reduction and rigid internal fixation o ccurred without the formation of osseous callus, and no marked abnorma lities were discernible in the physis. CLINICAL RELEVANCE: These findi ngs indicate that the healing of Type-III and Type-IV epiphyseal injur ies treated with anatomical reduction and rigid internal fixation occu rs with no apparent changes in the structure and function of the growt h-plate cartilage. The compression of the fragments prevents the forma tion of vascular anastomoses between the epiphyseal and metaphyseal ve ssels. The healing process results in a primary osseous union without callus formation.