Two cases of metallosis from metal-on-polyethylene total hips: an emerging problem.

This report describes 2 cases of metallosis from metal-on-polyethylene total hip replacements. Case 1 involved a Stryker rejuvenate implant, which has since been recalled. This patient had minimal symptoms, an elevated cobalt level, and loosening. The patient in case 2 had a Dupuys Pinnacle system, with symptoms of weakness, rash, and hip pain. Abnormal laboratory values include elevated sedimentation rate, C-reactive protein, creatinine, cobalt, and decreased hematocrit. Magnetic resonance imaging revealed synovial thickening and extracapsular edema. Although metallosis is a well-established complication of metal-on-metal implants, emerging data reveal that it also may be a problem in non-metal-on-metal implants such as either metal-on-polyethylene or ceramic-on-polyethylene implants, perhaps related to modular corrosion.