Experimental epiphyseal separation by torsional force.

Separation of the proximal tibial epiphysis from the metaphysis by torsional force was experimentally studied using cadaver bone preparations from 19 adolescent sheep. The energy needed to displace the epiphysis increased in correlation with an increase in the age of the animal. The separated epiphyseal and metaphyseal surfaces were examined using scanning electron microscopy. In the younger animals the separation line passed through the area of hypertrophied chondrocytes. In the animals more near skeletal maturity the separation occurred in a more sinuous fashion and also through spongious bone.