This is the second report from these doctors in Germany. At first they reported the results of a total wrist replacement after 18 months. They used an uncemented implant made of cobalt and chrome. Joint surfaces of the implant were coated with titanium.
Wrist replacements are fairly new. Although they’ve been used for the past 30 years, the newer and better designs today makes them like a new operation. However, they don’t have the stable results of hip and knee replacements yet.
Forty patients with rheumatoid arthritis were followed. At the time of the wrist replacement, the patients had good function, reduced pain, and were satisfied with the results. Over two years later, doctors reported on the long-term results.
In this latest study all the patients started developing problems after the 18-month mark. The wrist implant started moving and the wrist drifted into a position called ulnar deviation. This means the fingers drift away from the thumb. Wrist range of motion and grip strength was also much decreased.
Many patients had loosening of the implant because of bone softening and breakdown. Some had a complete dislocation of the wrist implant. The replacements had to be removed and the wrist fused for all 40 patients.
When the implants were removed, the doctors found quite a bit of wear on the joint surfaces. There were particles from the implant in and around the tendons and even into the fingers. The debris was stuck to the soft tissues and couldn’t be removed.
The doctors in this study were unsure why the implants failed. Perhaps there was loosening because cement wasn’t used to hold the parts together. Maybe the body reacted to the titanium alloy. Using the same implant a second time wasn’t possible because there was too much bone loss and soft tissue damage. Fusing the wrist was the only option.
The authors were very disappointed with the results of wrist replacements in patients with rheumatoid arthritis. They advised that the use of such implants be abandoned in these cases.