What is Thumb Arthritis (CMC joint arthritis)?
The thumb is the most common site for arthritis in the hand. The thumb has three joints and the CMC joint is the most commonly affected. Osteoarthritis and Rheumatoid Arthritis can both affect the thumb causing the cartilage that covers and protects the joints to wear out. Without the protective cartilage, the bones in the joint grind against one another wearing the joint down and causing pain and instability.
As the disease progresses, the CMC joint may slip out of place causing the thumb to collapse into the palm, forming a “Z” or zigzag deformity. This makes it difficult to open the thumb away from the palm and makes grasping and pinching progressively more difficult.
Symptoms of Thumb Arthritis:
- Pain at the base of the thumb, down by the wrist
- Pain when pinching or gripping, especially small objects like pens or tool handles
- “Grabbing” or sharp pain when you engage in a certain activity or even at rest
- The base of your thumb might “stick out” and look as though it is a little ledge or step
Generally treatment includes anti-inflammatory medicine to reduce pain and inflammation and a splint for support or rest. How much medication and what level of rest or support is needed depends on when the joint hurts, what makes it hurt, and how much it hurts.
Short or hand-based splints that allow full or limited wrist motion and thumb motion can be recommended. They are generally flexible splints that support by applying compression and may also include flexible stays or thin plastic inserts for added support.
Splinting options by level of support:
For light support, the 3pp ThumSling (pictured below) supports the CMC joint and applies light compression to help reduce the slippage and grinding on the joint.
For moderate support and rest of more involved joints, the 3pp Ultra Spica (pictured below) and ThumSaver MP are designed to protect but still allow function.
Firm splints such as the ThumSaver CMC Long or 3pp ThumSpica Plus (pictured below) immobilize the thumb when full rest is needed. Professional fitting is recommended.
It is important to look for a splint that supports the CMC joint without limiting more motion than is necessary. If your thumb is painful only when you do certain tasks, choose a splint that supports but allows motion. If your thumb is painful even at rest, choose a splint that immobilizes the thumb. Often, because the pain from CMC joint arthritis tends to vary with activity, you may need both.
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