A biomechanical comparison of screw and wire fixation with and without polymethylmethacrylate re-enforcement for acetabular osteotomy stabilization in dogs

Abstract

Objective - Compare the biomechanical characteristics of screw and wire fixation with and without polymethylmethacrylate (PMMA) re-enforcement for acetabular osteotomy stabilization in dogs. Animals - Pelves removed from 8 adult mixed breed dogs weighing between 25 and 30 kg. Procedure - The pubic symphysis of each pelvis was split and a central transverse acetabular osteotomy was performed. One hemipelvis from each dog was stabilized with the composite fixation (interfragmentary Kirschner wire, two screws and a figure-of-eight orthopedic wire with PMMA). The contralateral hemipelves was stabilized with an interfragmentary Kirschner wire, two screws, and a figure-of-eight orthopedic wire without PMMA. All hemipelves were tested in bending by using a materials testing machine at a cross head speed of 5 mm/min. An extensometer was placed on the dorsomedial surface of the hemipelves centered over acetabular osteotomy to record distraction of the osteotomy during loading. A load/deformation curve and a load/distraction curve was produced for each hemipelvis. The slope for the initial linear portion of the load/deformation curve and the load/distraction curve, yield load and maximum load sustained were compared between repair groups using a paired Mest with P