Valgus instability and related factors beyond 2 years following unlinked total elbow arthroplasty.

HYPOTHESIS AND BACKGROUND:Total elbow arthroplasty (TEA), categorized into linked and unlinked types, is a commonly reported treatment for rheumatoid arthritis of the elbow. Although unlinked TEA preserves bone, it may result in instability. This study aimed to assess the outcomes of unlinked TEA in rheumatoid arthritis of the elbow beyond 2 years and to identify factors correlating with postoperative valgus instability of unlinked TEA. METHODS:This study included patients who underwent TEA for rheumatoid arthritis of the elbow at our department between August 2009 and January 2017, with a follow-up period exceeding 2 years. Elbow joint range of motion (ROM) and clinical scores were evaluated preoperatively and at the final follow-up. Factors contributing to valgus instability, such as the Larsen grade, sex, age, side, preoperative ROM, postoperative ROM, implant placement, preoperative carrying angle, and the use of biological disease-modifying antirheumatic drugs (bDMARDs), were also assessed. RESULTS:This study encompassed 26 elbows from 23 patients, with a mean patient age at surgery of 64.8 years and a mean follow-up duration of 92.4 months. Significant improvements were observed in the ROM (extension: from -31° preoperatively to -21° postoperatively [P = .02], flexion: from 116° to137° [P < .001]), Japanese Orthopaedic Association-Japan Elbow Society Elbow Function Score (from 45.9 to 86.3 points [P < .001]), and Mayo Elbow Performance Score (from 43.6 to 91.7 points [P < .001]). At the last follow-up, 2 elbows exhibited radiolucent lines around the humeral stem, whereas 7 had valgus instability. Factors correlated with valgus instability included total arc at the final follow-up, preoperative carrying angle, and the use of bDMARDs. DISCUSSION AND CONCLUSION:Unlinked TEA demonstrated favorable midterm outcomes for rheumatoid arthritis of the elbow, albeit with occasional valgus instability. Surgeons should consider preoperative carrying angle and bDMARD use, and exercise caution regarding intraoperative extensions.