Long-term follow-up study of Kudo Type-5 elbow prosthesis in patients with rheumatoid arthritis: minimum 10-year clinical outcomes.

Objectives: Rheumatoid arthritis often leads to debilitating damage in the elbow joint, which may require total elbow arthroplasty (TEA). The Kudo TEA is one of the unlinked type prostheses with reportedly favorable outcomes. However, there is limited information available regarding its long-term performance. This retrospective study aimed to evaluate the long-term survivorship and identify risk factors associated with failure of the Kudo Type-5 TEA in patients with rheumatoid arthritis (RA), specifically exceeding 10 years.

Methods: Patients with RA who underwent TEA with the Kudo Type-5 prosthesis from 1998 to 2009, with a minimum ten-year follow-up, were included. Failure, defined as revision surgery or radiographic loosening, was assessed using the Kaplan-Meier method. The patients' demographic data, radiographic measurements, range of motion, Mayo elbow performance score (MPES), and the material of the ulnar component were compared between the elbows with and without failure. Univariate analysis identified factors affecting long-term survivorship.

Results: Among 49 elbows in 38 patients with a mean follow-up of 13.4 years, significant improvements in flexion range and MPES were observed. The failure rate was 39%, occurring in 19 elbows. Among these failures, 13 cases were attributed to issues with the ulnar component, making it the most common cause. The overall survivorship rate of the Kudo Type-5 prosthesis at ten years was 78%, as calculated using the Kaplan-Meier method. Factors associated with a higher failure risk included a shorter duration from RA onset to surgery (17.2 ± 5.8 years vs. 23.3 ± 8.7 years; p = 0.01), a lower preoperative stability score of MPES (6.6 ± 4.1 vs. 9.3 ± 1.7; p < 0.01), larger implant deviation assessed by the implant deviation index (9.3 ± 1.3% vs. 5.4 ± 1.1%; p = 0.03), and the use of the all-polyethylene ulnar component (79.0% vs. 46.7%; p = 0.04).

Conclusion: Although the Kudo Type-5 prosthesis demonstrated satisfactory results in patients with RA, failures occurred to some extent over a long-term follow-up period. Careful monitoring should be conducted, particularly in cases with a short duration from RA onset to surgery, preoperative instability, misalignment of the implant and the use of the all-polyethylene ulnar component.