Objective: The purpose of this study was to describe the radiographic outcomes of pyrolytic carbon implants in the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints, determine the most common complications, and assess risk factors associated with complications.
Materials and methods: Retrospective review over a 10-year period was performed to identify patients with pyrolytic carbon implants of the PIP or MCP joint. All available radiographs were reviewed and correlated with clinical information. Statistical analysis included calculation of the complication rate, Phi coefficient for variable association with a complication, and Kaplan-Meier survival.
Results: Forty-seven implants in 43 patients were reviewed. There were 30 PIP and 17 MCP implants. The mean age of the patients was 56 years. The mean radiographic follow-up was 17.2 months (range, 1-82 months). The indication for arthroplasty included osteoarthritis (55.3%), trauma (27.7%), rheumatoid arthritis (12.8%), and benign neoplasm (4.26%). Fourteen second surgeries were performed: four for retrieval and 10 for revision. Radiographic abnormalities included subsidence (31.9%); loosening with dorsal or volar tilt of the stem (34.1%); loosening without tilt (6.38%); periprosthetic fracture (8.51%); and ulnar subluxation of joint (4.26%). There was no statistical association (r < 0.001) between 1 mm or less of symmetric lucency around the distal implant with future complications. The sensitivity of radiography for the clinical failure of the implant was 28.6% and specificity, 30.3%.
Conclusion: Of the 47 pyrolytic carbon PIP and MCP implants, 14 (29.8%) required surgical revision or retrieval, mostly for extensor tendon contractures. Compared with the clinical survival of the implant, radiographic survival was poorer and did not correlate with clinical survival. Tilt of the proximal stem and subsidence were the more common radiographic complications.