Can the Bone Mineral Density of the Non-fractured Contralateral Hip Predict Medial Migration of Helical Blade-type Lag Screws in Osteoporotic Hip Fractures?

Abstract

Background: In this study, we performed a biomechanical tests on the osteoporotic femoral heads to validate whether the bone mineral density (BMD) measured at the non-fractured contralateral hip can predict the BMD and potential medial migration of helical blade-type lag screws on the fractured femoral head.Methods: Twenty-four osteoporotic femoral heads were retrieved from patients with femoral neck fracture undergoing hip arthroplasty. The patients had their BMD measured from the contralateral hip using dual-energy X-ray absorptiometry prior to surgery. The BMD of the retrieved femoral heads was measured using micro-computed tomography. The mechanical properties for the medial migration of lag screw were measured by performing an uniaxial compression test on the femoral head using a helical blade-type lag screw. Statistical analysis was performed to determine the correlation among the BMDs of the non-fractured contralateral hip and the retrieved femoral head and the mechanical properties of the fractured femoral head.Results: The mean BMD of the contralateral hip was 0.60±0.14 g/cm2 in the neck region and 0.63±0.15 g/cm2 in the total proximal femur. The mean BMD of the fractured femoral head was 463.3±48.05 mg HA/cm3. The mechanical properties of the fractured femoral head were measured to be 0.92 kN for the maximum compressive load and 14.50±5.48 kN for the accumulated compression load. In the analysis of the correlation among the parameters, we found no correlation between the BMD of the non-fractured contralateral hip and the mechanical properties of the fractured femoral head. In addition, we observed no correlation between the BMD of the fractured femoral head and that of the contralateral hip.Conclusions: Our results indicate that the BMD of the contralateral hip does not reflect the BMD or the mechanical properties of the fractured femoral head. Therefore, helical blade-type lag screw migration may not be predicted from the BMD of the non-fractured contralateral hip.