RADIOGRAPHIC COMPARISON OF CEMENTED AND UNCEMENTED TOTAL HIP ARTHROPLASTY AND HIP RESURFACING

Abstract

Introduction: The technology available for replacing/ resurfacing the hip joint is constantly evolving. The practicing surgeon can now choose from a wide array of components to perform a cemented, hybrid, uncemented total hip arthroplasty (THA), or a hip resurfacing. The potential advantages and disadvantages of all have been widely reported in the literature. The choice of implant depends on a number of factors, such as, patient age and level of activity, hip anatomy, and the surgeons’ preference and expertise. The aim of our study was to evaluate and compare the restoration of hip biomechanics following the insertion of three different, commonly used constructs.

Methods: We compared the postoperative anteroposterior radiographs from 40 patients who underwent cemented THA, 45 patients who underwent uncemented THA and 40 who underwent Articular Surface Replacement (ASR). All procedures were carried out by a single consultant orthopaedic surgeon who was experienced in the insertion of all three different implant designs. The acetabular offset and height, and the femoral offset and limb length were measured, with reference to the normal contralateral hip, using accepted methods.

Results – Hip resurfacing resulted in a significant reduction in femoral offset (p < 0.001), with accurate restoration of limb length. Both cemented and uncemented THA resulted in a significant increase in femoral offset, both also resulted in significant leg – lengthening (p< 0.001), this was more marked with uncemented THA’s. Radiological measurements of the acetabular reconstruction were similar in all groups.

Discussion – Restoration of normal hip anatomy optimises biomechanical function and reduces wear of components. The ASR group had the most accurate restoration in comparison to the two other groups. The reduced femoral offset associated with the ASR group may reduce the lever arm of the abductor muscles however this is unlikely to be clinically significant.