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Introduction

Implantation of distal ulnar head prosthesis is primarily indicated in treatment of degenerative, rheumatoid, and post-traumatic arthritis at the distal radioulnar joint (DRUJ). This study evaluates the success of the distal ulnar head prosthesis by exploring the short-term patient function and the incidence of complications.

Materials and Methods

The study was designed to retrospectively review patients who were treated with distal ulnar prosthesis arthroplasty. The inclusion criteria required patients to have at least one implanted ulnar head prosthesis and a minimum of 1 postoperative year of clinical follow up. Preoperative and postoperative physical exam findings and radiographs were reviewed.

Results

There were 10 patients: 5 men and 5 women. The mean age at surgery was 58.6 years (range 37.9-72.2 years). Nine patients received a non-cemented Avanta ulnar head implant. The implant type was unknown in 1 patient. The diagnoses were osteoarthritis (3), rheumatoid arthritis (2), post-traumatic arthritis (3), and revision surgery from previous Darrach and ulna head prosthesis arthroplasty (2). Seven implants were right sided and 3 were left sided. The average postoperative follow-up duration was 33.9 months (range 15.5-68.7 months). The mean preoperative pronation was 78.1 degrees and the mean preoperative supination was 77.5 degrees, n=8. The respective average postoperative values were 75.6 degrees and 76.3 degrees, n=8. In the treated wrist, the average grip strength was 21.7 lbs preoperatively and 52.0 lbs postoperatively, n=4. The x-rays of all 10 wrists were analyzed at an average follow-up of 25.0 months (range 1.2 – 65.5 months). Two implants demonstrated evidence of loosening, 1 wrist demonstrated loosening and cortical thinning, and 2 wrists showed cortical thinning. Other complications included heterotopic ossification, pain with rotation, and infection leading to eventual implant removal. In 3 patients, there were no significant findings or complications.

Discussion and Conclusion:

The treatment of end-stage DRUJ arthritis remains a difficult problem. In our patients, although the change in range of motion was not clinically significant, a relatively high incidence of unfavorable radiographic findings and complications were observed in the short term. These results may indicate a necessity to alter either the design of the implant, the method of fixation, or both. However, longer clinical follow-up and patient rated outcomes are required in order to determine the true effectiveness of the described ulnar head prosthesis.