PURPOSE:
The purpose of the study was retrospectively review long-term outcomes of pyrolytic carbon implant arthroplasty of the proximal interphalangeal joint (PIPJ), especially evaluating functional outcomes, complications and radiographic results.
METHODS:
From April of 2002 to 2008, a consecutive series of 164 primary pyrolytic carbon implant arthroplasties were performed in 108 patients. The preoperative diagnosis was osteoarthritis in 54, rheumatoid arthritis in 19, posttraumatic arthritis in 29 and psoriatic arthritis in 5. Clinical assessment included active range of motion (ROM), grip power, pain, stability and complications. Radiographic evaluation included deformity, loosening and heterotopic bone formation. The data record ended if the implant failure. The average follow-up time was 23.6 months (ranged from 10 days to 76 months).
RESULTS:
The number of finger with data collection from 3month, 6month, 1year, 2 year to 6 year follow-up was 146, 129, 92, 67, 52, 24, 11 and 5 respectively. The active ROM value improved from 39.8° to 50.5° at 1-year follow-up. The best performance of active ROM appeared in the duration between 6 months to 1 year. Then the active ROM decrease 2.0°-8.8° in range every year until 5-year follow-up. The mean grip power in every follow-up time point except 3-month follow-up was also better than pre-operative data. Complete pain relief was present in 85.4 % of replaced PIPJ. 55 joints had received additional procedures to improved joint function; 30 for major revision of the implants. The other 25 revisions were for minor reason without involving implant. The major revision arthroplasty rate was 18.3 % and the infection rate was 1.2 %.
Radiographic subsidence was 2.1 mm in average on proximal phalangeal bone; 0.9 mm on middle phalangeal bone. The coronal plane angulation was corrected from 13.6° to 5°. Grossly, we found the tendency that the implant component tip migration to radial side over radial fingers and volar side over all the fingers.
CONCLUSION:
The pyrolytic carbon implant for PIPJ arthroplasty is effective in providing pain relief and better grip power. The active ROM improvement could be encouraging after surgery. However, the potential of gradual active ROM downhill after 1 year follow-up should be concerned.