Abstract
Introduction:
Demand for total hip arthroplasty (THA) continues to rise and as such there is a concurrent presumed increase in the incidence of periprosthetic femoral fractures. Several studies have previously demonstrated differences in fixation technique and biomechanical advantages of various cerclage constructs in fixation of femoral periprosthetic fractures. The purpose of this study is to determine the most effective combination of cerclage materials and technique in fixation of of periprosthetic fractures during cementless THA.
Methods:
Thirty fourth generation synthetic femora were tested in axial compression and torsion. Femurs were placed in a standardized mount and a press fit hip prosthesis was implanted by one senior surgeon. After broaching but prior to implant placement, a band saw was used to create a Vancouver B1 fracture below the level of the lesser trochanter. The implant was then placed in the femur. Four different cerclage constructs were then created using two of the following: 1) hose clamp, 2) metallic cable, 3) synthetic cable, 4) monofilament wire. All cables were placed using tensioning devices to standardize final cerclage tension. Additional constructs were created increasing the number of cerclage cables/wires to three and then four, evenly spaced across the implant. Axial compression and torsion were assessed to failure for all constructs using standard Instrom testing criteria. Cost analysis was performed for each construct.
Results:
Data suggests that Construct 1 demonstrated superior results in both axial compression and torsion in all trials, increasing with the number of clamps used. Construct 4 demonstrated inferior results in both axial compression and torsion, although increasing the number of wires significantly increased the strength of the construct. Construct 2 and 3 were equivalent.
Conclusion:
Increasing the number of cerclage cables/wires significantly increases the strength of the construct in both axial compression and torsion. Overall strength in order of strongest to weakest is as follows: hose clamp, metallic cable, synthetic cable and monofilament wire. It is reasonable to consider monofilament wires as a viable fixation option given lower cost and overall strength at physiologic loads.
