Surface Replacement: The Hip Replacement of the Future?

Abstract

Surface replacement is a significant development in the evolution of hip arthroplasty. Unlike conventional total hip arthroplasty, surface replacement does not require resection of the femoral head; thus, it presents a potentially effective, bone-conserving alternative to conventional replacements. Moreover, conversion to total hip replacement can be made readily, if necessary, with fewer complicating factors than with total hip revision surgery. It offers the greatest potential benefit to patients who are young and physically active. Previous surface replacement used metal-on-polyethylene devices; however, the large ball size of the femoral component contributed to high volumes of polyethylene wear. For some patients, osteolysis occurred due to tissue reaction to polyethylene debris, resulting in aseptic component loosening. Recent advances in technology have allowed metal-on-metal implants to be manufactured with great precision. Hybrid and all cementless fixation, have both shown good early results without the prevalence of loosening seen with polyethylene bearings. Metal-on-metal surface replacement has proved to be quite successful. Results from patients with metal-on-metal devices, especially those with ConservePlus™ implants, show no complications; moreover, there has been an absence of pain and a return to high functional levels, including participation in sports. Due to the large ball size, metal-on-metal devices offer high stability and low dislocation rates. Hemisurface replacement of the femoral head has also proved to be successful in patients with osteonecrosis with or without collapse of the femoral head, when the acetabulum remains relatively normal. For this type of surgery, some acetabular articular cartilage must be preserved. With high survivorship over time, it has emerged as the treatment of choice for this patient group.