What's new in orthopaedic research.

Abstract

The last year has brought substantial advances in many areas of orthopaedic research. Probably the most impressive is the shift from a focus on implant design, obviously the most successful treatment of end-stage degenerative joint disease, to the potential for earlier interventions, or solutions, that could increase the life of the cartilage, bone, tendons, and ligaments of the joint. The search for biological solutions touches on all aspects of orthopaedic research: response to implant materials, development of tissue-engineered cartilage and bone, and discovery of biomarkers for joint disease. We will review some of the latest advances made and questions raised in this new age of orthopaedic research. This year's combined Orthopaedic Research Society/American Academy of Orthopaedic Surgeons symposium dealt with clinical, engineering, and biological issues related to implant wear. This symposium complemented a recent publication by the Academy and the National Institutes of Health on implant wear1. The manifestations of wear of total hip and knee replacements have been well documented in the past decade. Most commonly, osteolysis progresses in a slow, linear fashion and is not detectable radiographically until five years or more postoperatively, when periprosthetic radiolucent zones may be observed. Rates of osteolysis as high as 60% have been reported in association with certain hip implants2. In addition to wear of hip and knee replacements, wear of total shoulder and elbow replacements is an emerging problem that should be carefully monitored in the future. ### Biological Aspects of Wear-Osteolysis Particle-induced osteolysis is a primary cause of aseptic loosening. A consensus has emerged that the predominant process is one of cytokine production in response to phagocytosis of implant wear particles resulting in increased proliferation and differentiation of osteoclast precursors into mature osteoclasts. Several cell types, including macrophages, fibroblasts, and osteoblasts, observed in periprosthetic tissues are believed to play a …