Experimental epiphysial distraction producing and correcting angular deformities.

Angular deformities of the distal radius of 15 sheep were induced by asymmetrical epiphysial distraction. Eleven sheep were between 10 and 20 weeks old; four were older than 24 weeks. Gradual distraction on the medial side of the limb caused partial separation of the epiphysis from the metaphysis, resulting in a valgus deformity. The distraction device was removed three to six weeks after insertion. Spontaneous correction of angulation with growth occurred in the younger sheep; but when the induced valgus angle exceeded 20 degrees correction was poor. In two sheep further distraction was applied on the lateral side and this produced complete correction. Premature closure of epiphyses did not occur after distraction and longitudinal growth of the bone remained normal. In the older sheep asymmetrical distraction succeeded in inducing angulation in only one case, and correction was poor.