Surgeons have spent the last 40 years working on finger and wrist joint replacements for patients with painful and crippling arthritis. Different designs have come and gone. Materials have improved. Long-term results are now available after 20 to 40 years of follow-up with patients.
In this report, surgeons from the University of Cincinnati College of Medicine give a review and an update on joint replacements for the hand and wrist. When available, long-term results are given.
Three joint replacements are included: proximal interphalangeal (PIP) joint, metacarpophalangeal (MCP) joint, and the wrist. The PIP joints are the middle joints of the fingers. The MCP joints form what we refer to as the knuckles. Before implants were developed, patients had to rely on a joint fusion to stop their pain. Unfortunately, a fusion also limits motion.
Implants for the PIP joints made of silicone were popular at first. But long-term results showed motion wasn’t improved. Deformities were not corrected. And over time, the implant could break or sink down into the bone. The same problems were reported with MCP joint implants. The early good results reported with silicone implants tend to decline after 10 years.
Pyrolytic carbon implants had variable results. Pain was improved but strength and motion were not changed. Researchers are now studying titanium as a potentially better material for these implants.
Over the years, wrist joint replacements have undergone similar changes in design, materials used, and surgical technique. Wrist implants today are usually metal-on-polyethylene (plastic). The stem that fits into the forearm bone is porous coated. This gives the surface a rough base for bone to fill in and around.
Implant loosening and wrist imbalance are the two main problems with wrist replacements. Pain can get worse when the joint does not match up or if the joint pinches the soft tissues.
Two new designs are being investigated to help with these problems: the biaxial total wrist and the Universal prosthesis. Long-term results of these new implants aren’t available yet.
However, early results suggest these implants make a good choice for patients with low demand for wrist motion and strength. It’s still better than a wrist fusion and the patient can always have a fusion later if the implant fails some years down the road.