Radiology of the resurfaced hip

Abstract

Hip resurfacing arthroplasty is an increasingly common procedure for osteoarthritis. Conventional radiographs are used routinely for follow-up assessment, however they only provide limited information on the radiological outcome. Various complications have been reported in the scientific literature although not all are fully understood. In an effort to investigate problematic or failing hip resurfacings, various radiological methods have been utilized. These methods can be used to help make a diagnosis and guide management. This paper aims to review and illustrate the radiographic findings in the form of radiography, computerized tomography (CT), magnetic resonance imaging (MRI), and ultrasound of both normal and abnormal findings in hip resurfacing arthroplasty. However, imaging around a metal prosthesis with CT and MRI is particularly challenging and therefore the potential techniques used to overcome this are discussed.

Current Concepts in Hip Arthroplasty Imaging: Metal-on-Metal Prostheses, Their Complications, and Imaging Strategies

“…Valgus positioning optimizes the load-bearing capacity of the femoral neck and is recommended to lessen the chance for femoral neck fracture. 4,[15][16][17] Fracture of the femoral neck after hip resurfacing arthroplasty is a well-recognized early complication, with a reported incidence of approximately 1.5% in one case series. 17 Varus positioning of the femoral component has been shown to be a risk factor for fracture of the femoral neck (Fig.…”

“…[4][5][6][7][8] With a longer average life span and increased activity levels, this population is particularly prone to high failure rates with conventional metalon-polyethylene total hip devices secondary to polyethylene wear and subsequent osteolysis. Metal-on-metal designs provide the theoretical advantage of reduced implant-bearing surface wear.…”

“…2,4 Hip resurfacing arthroplasty offers the distinct advantage of preserving femoral bone stock, thus facilitating simple revision surgery on the femoral side. 2,[4][5][6] Recent clinical studies of second-generation metal-onmetal total hip arthroplasty designs have reported favorable results based on outcomes and survivorship. However, few studies have used a randomized controlled design to compare metal-on-metal designs with other bearing surfaces.…”

“…Additional designs include a dysplasia cup, for patients with superolateral acetabular deficiency, and a mid-head resection arthroplasty, for cases of avascular necrosis or extensive femoral head cystic change. 4 The US Food and Drug Administration has approved 3 metal-on-metal hip resurfacing systems, namely, the Birmingham Hip Resurfacing System (Smith & Nephew, London, UK), Conserve Plus Total Resurfacing Hip System (Wright Medical Technology, Arlington, TN), and the Cormet Hip Resurfacing System (Corin, Cirencester, UK).…”

“…10,14 In resurfacing hip arthroplasties, component position is extremely important, more so in comparison with conventional total hip arthroplasties. 4,8,[14][15][16] In the anteroposterior (AP) plane, the femoral component should be in a relative valgus position of approximately 5-10°relative to the femoral neck. Valgus positioning optimizes the load-bearing capacity of the femoral neck and is recommended to lessen the chance for femoral neck fracture.…”