Plating of rat femoral shaft osteotomies: report of a technique and preliminary results.

Development of a small animal model to study fracture healing has been challenging in the past. Stabilization of osteotomy in small animals has mainly been accomplished using Krishner wires. Krisheners offer stabilization, but can result in a significant increase in fracture callus. An alternative approach using a modified twenty-five hole 1.5 mm stainless steel plate was used to stabilize a 5 mm femoral osteotomy, and fracture stabilization was followed for a period of 15 weeks in adult male rats. Fifty four of fifty-six animals (96%) were followed 15 weeks post operatively. Within the first few days post operatively, two animals showed evidence of fixation failure due to technical error, and the animals were humanely sacrificed. Otherwise, after two days post-operatively the remaining 54 animals were weight bearing. At 15 weeks post-operatively, the fracture was stable with little bone formation evident. Therefore, this technique can effectively be used to evaluate compounds which will enhance bone formation. The technique allows for stable fixation of the control with little callus formation and bone ingrowth. This model will allow for x-ray analysis to follow bone growth in relation to bone enhancing compounds.