Abstract
Purpose
To analyse the early results of unconstrained pyrocarbon joint replacements in patients with osteo-arthritis of the metacarpo-phalangeal joints.
Background
Silicone arthroplasty, as introduced by Swanson in 1962 has remained the most popular procedure to treat arthritis of the metacarpo-phalangeal (MCP) joints. However, despite providing good pain relief, they have shown to demonstrate breakage rates up to 82% at 5 years. This is of great concern in the osteoarthritis (OA) patient group, who tend to be younger and have higher functional demands compared to their rheumatoid counterparts. The newer unconstrained pyrolytic carbon MCP joint prostheses may therefore be more suitable in OA patients whose soft tissue constraints are intact and whose hand function is strong. This study is the first to analyse the results of this implant in a cohort of OA patients only, with prospective data.
Methods
19 primary pyrocarbon metacarpo-phalangeal joint replacements, in 11 patients (5 men and 6 women) were reviewed, with prospective data collection. The diagnosis was primary osteoarthritis in all patients. The mean age at operation was 66.4 years (range 55–82 years). 2 patients underwent concomitant trapiezectomy and one underwent DIPJ fusion. All patients were right hand dominant −75% underwent surgery in their dominant hand. Eleven of the nineteen joints were performed in the index finger, with the remainder in the middle finger. Mean follow up is 22.1 months (range 11–37).
Results
At the 3 month post-operative hand therapy assessment, the arc of motion had improved from a mean of 32 degrees to 45 degrees and flexion had improved from a mean of 51 degrees to 66 degrees. Grip strength improved from a mean 20 to 27Kg. DASH scores significantly improved from a mean of 40 to 10 (p=0.01). All patients were satisfied with their outcomes and would have the surgery again.
Pre-operative radiographs demonstrated joint narrowing in all patients but no evidence of heterotopic ossification, cystic change or erosions. Post-operatively, there has been no radiographic evidence of joint dislocation, resorption stress-shielding, loosening, migration or heterotopic ossification.
There were three intra-operative complications of phalangeal fractures that were immediately treated with a cerclage wire. In one patient there has been a fracture of the proximal phalangeal implant at 14 months which was asymptomatic. One patient has required revision for mal-rotation of the implant leading to loss of index finger supination.
Conclusion
Our results demonstrate excellent early results of pyrocarbon MCP joint arthroplasty in OA patients.
