Clinical outcome of Niigata-Senami-Kyocera modular unconstrained total elbow arthroplasty for destructive elbow in patients with rheumatoid arthritis.

Background: Total elbow arthroplasty (TEA) is a treatment option for destructive and painful unstable elbows in rheumatoid arthritis (RA). We evaluated the clinical outcomes of unconstrained TEA (Niigata-Senami-Kyocera modular system).

Methods: Seventy-five unconstrained TEAs were performed in patients with RA (mean age, 64 years; age range, 41-79 years; follow-up rate, 97%). Outcome measures included the Japanese Orthopaedic Association (JOA) functional evaluation score for the elbow joint (JOA score), range of motion, and arc. Bone ingrowth of the humeral component, the incidence of stress shielding around the humeral component, the incidence of loosening of the ulnar component, complications, and the survival rate were investigated.

Results: The mean follow-up period was 5.2 years (range, 2-11.3 years). The JOA elbow score improved from 42 points preoperatively to 87 points postoperatively (P < .0001). Each specified item improved (P < .0001). Flexion improved from 109° to 134°; the flexion-plus-extension arc improved from 70° to 108° (P < .0001). Bone ingrowth of the humeral implant was achieved in all elbows. Stress shielding of the humeral component was detected in 11 elbows (14%); it was significantly higher in 10- and 9-mm-diameter humeral stems than in 8-mm-diameter humeral stems (P = .008). The ulnar component showed no loosening except in 1 elbow owing to infection. Complications were detected in 9 patients (9 elbows, 12%): periprosthetic infection (3), fracture (4), and dislocation (2). The survival rates were 97% at 5 years and 93% at 10 years postoperatively.

Discussion: The Niigata-Senami-Kyocera modular system for patients with RA showed good outcomes. Stress shielding can be avoided by using an 8-mm-diameter humeral stem.