Evaluation of an unconstrained pyrocarbon prosthesis (Ascension) in the treatment of idiopathic degenerative arthritis of the proximal interphalangeal joint of the hand.
In this study 10 patients (13 implants), that were treated with this type of prosthesis between February 2002 and January 2005 were clinically and radiologically studied.
All but one patient were satisfied with the postoperative situation and would agree to another operation. A significant pain reduction was observed. The average ROM was 58 degrees. Five patients demonstrated a free extension, two patients had a swan neck deformity, which could be actively compensated for, and the remaining six patients had an extension deficit of 30-45 degrees. The average flexion was 76 degrees (+/-12 degrees). X-ray examination was unremarkable in eight patients with a regular position of the endoprosthesis. However, in five patients significant radiolucent lines (>or=1 mm) were observed. So far, a luxation of the prosthesis has not occurred and all implants are still in-situ. However, a dorsal tenoarthrolysis had to be performed in 3 patients.
The results of this study show a high rate of patient satisfaction with a significant pain reduction. A missing osteointegration may be an explanation for the radiological results. The prosthesis has to be closely monitored in the future. Long-term results with a higher number of patients are necessary. A central registry for finger implants is recommended.