NEUFLEX AND SWANSON METACARPOPHALANGEAL IMPLANTS FOR RHEUMATOID ARTHRITIS: A PROSPECTIVE CONTROLLED CLINICAL TRIAL

Abstract

This prospective controlled clinical trial compares the outcomes of metacarpophalangeal (MCP) arthroplasty in rheumatoid arthritis patients using the Swanson (S) and NeuFlex (N) MCP implants.

Forty hands (thirty-seven patients) were randomised and evaluated preoperatively and at one year following MCP arthroplasty in digits two to five for range of motion (ROM; active and passive extension and flexion), ulnar drift and grip strength.

Both implants restored extension and corrected flexion deformities. There was no significant difference in extension of all digits (summed) between the NeuFlex and Swanson implants (N: −20.8°; S: −13.8°; p=0.29). The NeuFlex implant, which is pre-flexed at 30°, preserved more flexion at the MCP joint than the Swanson implant in all digits (summed) (N:74.5°; S:55.8°; p=0.005), with the greatest difference observed in the fifth digit (N:69.6°; S:48.7°; p=0.009). The total arc of motion improved in all digits, with no significant differences between the Neu-Flex and Swanson groups in the second through fourth digits (N:53.8°; S:43.8°; p=0.154); a significantly greater improvement was observed in the NeuFlex group for the fifth digit (N:53.3°; S:42.5°; p=0.028). Both implants corrected ulnar drift deformity, while neither led to loss of grip strength.

Hand function as measured by Sollerman score and Michigan Hand Questionnaire (MHQ) improved significantly in both groups (p=0.0119, p< 0.0001, respectively) with no significant difference between the Swanson and NeuFlex implants, except for MHQ function, aesthetics, and overall scores, which demonstrated superiority of the Swanson.

Overall, there was a significant improvement in the range of motion, deformity and grip strength following MCP arthroplasty for the full patient group. While both implants restored similar amounts of extension, the NeuFlex implant maintained greater flexion and total range of motion, with the greatest difference in the fifth digit. The Swanson implant had better MHQ function and aesthetics subscores.