Proximal Interphalangeal (PIP) Joint Replacement

The proximal interphalangeal joint is the middle joint of the finger. Injuries to the proximal interphalangeal joint often lead to arthritis. The treatment of proximal interphalangeal joint arthritis starts with buddy taping of the finger to its neighboring digit and a steroid injection into the proximal interphalangeal joint. If significant proximal interphalangeal joint pain continues then the options for treatment are usually either fusion or replacement.

The proximal interphalangeal joint of the index finger is best fused. The index finger is used for pinch. When the index finger opposes the thumb to create power during pinch, this creates a significant sideways stress on the proximal interphalangeal joint. Current proximal interphalangeal joint replacements simply cannot handle this sideways stress, and will become unstable. On the other hand, fusion leads to a stiff but pain-free and stable platform for pinching. The loss of proximal interphalangeal joint motion is not a significant problem for the index finger.

Because the middle, ring and small fingers are used for grasp, motion of the proximal interphalangeal joint of these digits is important. For that reason, proximal interphalangeal joint replacement may be considered. As for most joint replacements, they have less problems as the patient’s age increases. The reason for this is because joint replacements have a limited ‘life expectancy’, and do not last as long in younger, higher demand individuals. Having said that, the newer joint replacements may be better suited for younger, higher demand individuals, within reason.

Proximal interphalangeal joint replacement is performed as an outpatient surgery. The newer metal and polyethylene (a fancy plastic) replacements usually work better than the pyrocarbon implants that were popular a few years back. An example of the newer (SR-PIP) joint implant can be seen at totalsmallbone.com

After proximal interphalangeal joint replacement, motion is started within a few days after surgery with hand therapy. Ultimate motion is about 50% of normal, about 60°. It is unclear how long the newer proximal interphalangeal joint replacements will last.

Unfortunately, these newer unlinked proximal interphalangeal joint replacements are not appropriate for patients with advanced rheumatoid arthritis. Rheumatoid arthritis is a much rarer inflammatory condition than the typical osteoarthritis (wear and tear) that is much more common. If you’re not sure what type of arthritis you have, unless a rheumatologist (arthritis expert) has formally diagnosed you with rheumatoid arthritis, you most probably have simple osteoarthritis or a similar condition. People with rheumatoid arthritis have poor ligaments. Because of this, unlinked replacements, such as the SR-PIP, will become unstable. In cases of rheumatoid arthritis, one-piece linked silastic (a type of rubbery plastic) replacements provide some intrinsic stability and are better options. The post-operative therapy is the same. In cases of rheumatoid arthritis, motion is limited more by the conditions of the finger’s tendons than the joint replacement itself.

So if you are suffering with proximal interphalangeal joint arthritis, there are now better treatment options than were previously available. Most patients are very happy with the pain relief and function afforded by these newer implants.

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