NeuFlex and Swanson Metacarpophalangeal Implants for Rheumatoid Arthritis: Prospective Randomized, Controlled Clinical Trial

Abstract

To compare postoperative range of motion (ROM) and function in a randomized prospective trial of Swanson and NeuFlex metacarpophalangeal (MCP) joint implants. A total of 33 patients who had rheumatoid arthritis underwent primary MCP arthroplasty of all 4 fingers in 40 hands; 20 received Swanson implants and 20 received NeuFlex implants. Exclusion criteria included diagnosis of other connective tissue disorders and previous MCP joint surgery. All participants followed the same postoperative rehabilitation protocol. The primary outcome measure was active MCP flexion. Secondary outcomes included active MCP extension, arc of motion, ulnar drift, function (Jamar grip strength and Sollerman hand function test), and the Michigan Hand Questionnaire. Patients were assessed preoperatively and 12 months postoperatively. Patients' mean age was 62.5 years (Swanson) and 58.1 years (NeuFlex) (p = .03). A total of 19 of 20 hands (Swanson) and 14 of 20 hands (NeuFlex) were from female patients. Preoperative active ROM was not significantly different. At follow-up, both groups demonstrated increased active extension and arc of motion (p < .001), reduced active flexion and improved ulnar deviation (p < .001), increased mean Sollerman and Michigan Hand Questionnaire domain scores (p < .001), and improved grip strength (p = .03). Active MCP flexion was significantly greater in all 4 digits of hands with NeuFlex implants compared with Swanson implants. The NeuFlex group demonstrated a greater total arc of motion in the little finger. Implant groups were not significantly different by individual digit for active MCP extension, ulnar drift, and composite flexion. Functional outcomes did not differ between groups. Patients with Swanson implants reported higher Michigan Hand Questionnaire scores in the function and aesthetics domains. Both implant groups obtained satisfactory clinical improvement after MCP reconstruction of the hand. The NeuFlex group demonstrated superior ROM, whereas the Swanson group had better self-reported function and aesthetics, but not objectively measured function. Therapeutic I.