Summary
An oblique femoral osteotomy model was created to determine if placement of cerclage wires, in relation to a neutralization plate (under vs over), affects bone healing and mechanical strength. In phase I of the study, femora of five skeletally mature mixed breed dogs were stabilized with a neutralization plate and three cerclage wires. One femur from each dog had the cerclage wires placed under the plate and the opposite femur had the cerclage wires placed over the plate. One dog was eliminated from the study due to nonunion. At eight weeks, the osteotomy sites were subjected to a torsional load and studied histologically. In phase II, 40 pairs of femora were used to determine whether cerclage wire placement and size affected the mechanical strength of the bone-plate model when torsional loads were applied. Within the limits explored in this study, placement of cerclage wires under the plate resulted in an osteotomy which was more resistant to torsional loads and was more advanced histologically towards bone healing. Cerclage wires placed under the plate appeared to provide improved osteotomy stabilization. Cerclage wire size did not significantly influence the mechanical strength of the bone-plate model.
The comparison of cerclage wire placement in relation to a neutralization plate, using an oblique femoral osteotomy model, is discussed. Resistance to torsional loads was greater in eight week healed osteotomies when the cerclage wires had been placed under versus over a neutralization plate.
Key words
Cerclage wires - Oblique osteotomy - Neutralization plate
