LARGE-DEFORMATION, FINITE-ELEMENT STUDY OF CHONDRODIASTASIS IN THE CANINE DISTAL FEMORAL EPIPHYSEAL PLATE

A large-deformation, finite-element analysis was conducted to model st ress fields around the developing growth plate as a first approach to comprehend the clinical application of traction for limb lengthening p rocedures. The model chosen was a cross section through the distal fem oral growth plate of a 14-week-old dog. The chosen section passed thro ugh two of the conformational bends (mammillary processes) formed by t he natural convolutions of the physis. Three different loading conditi ons were applied to the distal femoral epiphyseal model. The model als o examined the effects of different values of Young's modulus of the g rowth-plate cartilage. The cortical bone in all cases, experienced the highest stresses. In the growth plate, the highest principal stresses occurred where the physis intersects cortical bone. There were locali zed stresses that were higher than those that caused fracture in a rab bit model [Guse et al., J. Orthop. Res. 7, 667-673 (1989)]. Results al so indicated the following: a small tilt of 0.1 degrees in loading app lication increases the maximum principal stresses and the von Mises st resses in certain regions of the growth plate by about 8%; the shearin g stresses in the growth plate are sensitive to Young's modulus of the growth plate; and traction pins that do not grip the cancellous bone in the epiphysis will increase the regions of high principal stress in the growth plate.