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Newly Designed Wrist Implant Shows Improved Results

You may think TWA is an airline. But in the orthopedic world, TWA stands for total wrist arthroplasty. TWA is a joint replacement for patients with pain and loss of wrist motion from arthritis. Most patients getting a TWA have rheumatoid arthritis, but some have osteoarthritis.

Early attempts at TWA were had a high rate of failure. Doctors at the Mayo Clinic in Rochester, Minnesota, rolled up their sleeves and went to work on the problem. This study reports the results of using a newer TWA design.

The Biaxial TWA has been used for the last 20 years. In the 1990s, the design was changed to include a longer metacarpal stem. This part of the implant fits further into the bone of the third finger. The stem is about 50 percent longer than in the original design. Researchers believed a longer stem would give greater stability. They thought it wouldn't come loose as often as the shorter stem.

The authors of this study report good results using the Biaxial TWA with the long stem. All the patients had less pain after the operation. Overall motion was better, and everyone was satisfied with the results. No failures and no loose implants were reported. There were two cases of bone fracture in the middle finger, but this didn't change the final outcome for those patients.

Researchers are still looking for ways to reduce the rate of failure with wrist implants. A new type of implant is being studied. It combines cobalt-chrome parts with a titanium coating on the joint surface. The authors report early results of no failures, but long-term studies are still needed.

References: Marco Rizzo, MD, et al. Results of Biaxial Total Wrist Arthroplasty with a Modified (Long) Metacarpal Stem. In The Journal of Hand Surgery. July 2003. Vol. 28A. No. 4. Pp. 577-584.

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