Thumb CMC Arthritis
What Is Thumb CMC (Basal Joint) Arthritis?
Thumb CMC arthritis — also called basal joint arthritis — is wear-and-tear arthritis at the joint where the thumb meets the wrist, one of the most common arthritis locations in the entire hand. It causes pain with pinching and gripping and, for many people, is the single most limiting joint in daily hand use.
Why this joint wears out
The carpometacarpal (CMC) joint at the thumb's base allows for the wide range of motion that makes the thumb so functional — but that same mobility makes it prone to cartilage wear over time, especially with repetitive pinching and gripping. It's substantially more common in women than men and becomes more common with age.
Symptoms
Pain at the base of the thumb with pinching, gripping, or twisting motions (opening jars, turning keys, writing); a prominent or "squared-off" appearance at the base of the thumb as the joint changes shape; weakness with pinch-grip tasks; and in advanced cases, a hyperextended thumb joint from the body compensating for the arthritic base joint.
Diagnosis and Treatment:
X-rays confirm the diagnosis and stage of arthritis, which helps guide treatment. Nonsurgical options — splinting (particularly a thumb spica splint), activity modification, anti-inflammatory medication, and corticosteroid injections — provide meaningful relief for many patients, especially earlier in the disease. When pain and disability persist despite these measures, surgical reconstruction (most commonly removing the small trapezium bone and reconstructing joint support using a nearby tendon) relieves pain reliably while preserving thumb motion.
Frequently Asked Questions:
Is CMC arthritis the same as regular hand arthritis?
CMC arthritis specifically refers to the joint at the base of the thumb, which behaves somewhat differently and is treated somewhat differently than arthritis in the smaller finger joints, even though both are forms of osteoarthritis.
Will I lose thumb function after CMC arthroplasty surgery?
Most patients retain good functional thumb motion after surgery — the goal is preserving motion while eliminating the painful arthritic joint surface.
What is recovery like after CMC arthroplasty surgery?
The thumb is immobilized for the first 4 weeks. It can be challenging to perform everyday tasks with the affected hand. Full recovery takes around 3 months.
Do steroid injections help with thumb CMC arthritis?
Although they do not cure the disease, most patients get at least 3-4 months of relief from steroid injections into the joint. Once the joint has severe arthritis, there is not much downside to continuing injections until they are no longer working, at which point surgery is the best option.