Effect of femoral head diameter on tissue concentration of wear debris.

Although several studies have reported the physical properties of debris particles in tissues adjacent to failed total joint implants, few have correlated the results of particle analysis with other clinical and implant variables believed to influence implant wear. We retrospectively analyzed 41 fibrous membranes (from 35 patients) adjacent to failed acetabular cups from a single manufacturer and studied the relationship between three different femoral head sizes (26, 28, and 32 mm) and the characteristics of wear debris in the adjacent tissues. All total hip prostheses consisted of modular cobalt-chromium alloy femoral heads articulating with titanium-alloy-backed ultrahigh molecular weight polyethylene (UHMWPE) acetabular components from a single manufacturer. Large femoral head diameter (32 mm) was found to correlate significantly with large particle size (diameter and surface area, p < 0.05), high tissue concentration of particles (particle volume/gram of tissue, p < 0.01), and high rate of particle production (particles volume/month, p < 0.05). The results of these quantitative assays support the findings of radiographically based clinical studies that show higher volumetric wear associated with 32 mm femoral head components.