Modes of wear after semiconstrained total elbow arthroplasty.

BACKGROUND Osteolysis and aseptic loosening are increasingly recognized complications of total elbow arthroplasty. However, unlike the literature on total hip and knee arthroplasty, studies describing the mechanisms of these processes after total elbow arthroplasty are sparse. METHODS Semiconstrained total elbow arthroplasty components were retrieved from sixteen elbows (fourteen patients) at either revision surgery (at a mean of five years after implantation) for mechanical failure (fifteen elbows) or postmortem examination (one elbow). In all cases, the retrieved implant was the primary implant. The patterns of damage on these components were investigated with stereomicroscopy in correlation with clinical findings, serial radiographs, and histopathological observations. RESULTS All of the retrieved devices exhibited multiple modes of wear. Damage to the humeral and ulnar polyethylene bushings was nearly universal; twenty-seven of twenty-eight humeral bushings demonstrated asymmetrical thinning, while fifteen of sixteen ulnar bushings demonstrated elliptical plastic deformation. In addition, unintended metal-on-metal wear between bearing and nonbearing surfaces or between two nonbearing surfaces was commonly observed, typically in association with wear and deformation of the polyethylene bushings. Wear between the stem and the cement mantle was observed in most of the ulnar components. The histopathology of the periprosthetic tissues was similar in character to that observed in association with osteolysis and loosening of total hip and knee replacements, while analysis of the particulate debris revealed a preponderance of titanium alloy and polyethylene debris. Barium sulfate particles were also observed to a lesser extent. CONCLUSIONS Multimodal wear in total elbow replacements can lead to osteolysis, aseptic loosening, and prosthetic and periprosthetic fracture necessitating revision surgery. Polyethylene wear and damage, as well as unintended metal-on-metal wear, contribute to the periprosthetic particulate burden, which is likely pathogenic in these processes.