Thumb Arthritis

thumb ra

The thumb is the most common site for arthritis in the hand. Osteoarthritis (OA), also known as Degenerative Joint Disease (DJD) as well as Rheumatoid Arthritis (RA) affect the thumb. The thumb has three joints of which the basal or CMC joint is the most commonly affected.

The CMC joint is named for the bones that make up the base joint of the thumb - the trapezium, one of the small carpal bones of the wrist, and the metacarpal or long bone of the thumb. In OA, the cartilage that covers and protects the joints, wears out. Without the protective cartilage, the bones in the joint grind against one another wearing the joint down and causing pain and instability.

The MP joint (the middle joint at the level of the web space) and the IP (end knuckle) can be affected by cartilage breakdown and also by changes in the pull and alignment of the tendons that cross the joint. Changes at the CMC joint may cause it to sublux (slip out of place), causing the MP and IP joints to shift positions as well. The resulting zigzag or “Z” deformity is common in both OA and RA.


Pain in the CMC joint is the most common symptom of thumb arthritis. Pain is most commonly felt when trying to pinch or grip something tightly or when holding onto something small like a pen or a key. Pressure that pushes down on the thumb may also cause pain that is often described as “grinding” pain.

The MP joint of the thumb, is also a common site for pain as well as for deformity. This joint in particular may appear “crooked” resting in either a bent position or hyperextended. This is due to alteration in the pull of the ligaments that cross this joint.

How a 3-Point Splint Can Help

3-Point Products specializes in designing splints for thumb arthritis. For light support the 3pp ThumSling and 3pp ThumSling Long support the CMC joint and apply light compression to help reduce pain. The 3pp ThumSpica and 3pp ThumSpica Plus support the CMC joint to limit motion and provide protection and comfort.

For moderate to firm support, the ThumSaverMP realigns the thumb without limiting wrist motion. If you are experiencing severe pain or a sudden increase in pain and need to fully rest the thumb, the 3pp Ultra Spica and the ThumSaver CMC Long are recommended.

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