Low Success Rate for Universal Wrist Prosthesis in RA

Failure of Universal wrist prosthesis mainly due to carpal component loosening

FRIDAY, June 3 (HealthDay News) -- Wrist arthroplasty with Universal wrist prosthesis has a high failure rate in patients with rheumatoid arthritis (RA), mainly due to carpal component loosening, according to a study published in the May 18 issue of The Journal of Bone & Joint Surgery.

Christina M. Ward, M.D., from the University of Minnesota in St. Paul, and colleagues investigated the outcome of 24 total wrist arthroplasties with Universal wrist prosthesis in 20 patients with RA. After the index procedure, 19 wrists from 15 patients were followed up clinically and radiologically for an average period of 7.3 years. Disability of Arm, Shoulder, and Hand (DASH) scores, wrist range of motion, and standard radiographic findings were the main outcomes studied.

The investigators found that there was an improvement in the average DASH scores, from 62 points preoperatively to 40 points at the last follow-up. A mean improvement in total flexion-extension arc of 14 degrees at the latest follow-up resulted from mean wrist flexion and extension of 42 and 20 degrees, respectively. At the time of the latest follow-up, revision surgery for loose carpal movement had been done on nine wrists in eight patients, and one patient had wrist arthrodesis due to wrist instability. In addition, radiographic evidence of carpal component subsidence was identified in two wrists from two patients. The five- and seven-year survival rates for the original prosthetic components were 75 and 60 percent, respectively.

"Carpal component loosening remains an obstacle to predictable good long-term survival of this implant in patients with rheumatoid arthritis," the authors write.

One or more of the study authors disclosed financial ties to Kineticos Medical Inc.

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