Basal Thumb Arthritis

Basal thumb arthritis is wear-and-tear arthritis at the very base of the thumb, where the thumb's long bone meets a small wrist bone called the trapezium. It is one of the most common forms of arthritis in the hand. The cartilage that lets the bones glide gradually wears down, the joint space narrows, and the bones begin to rub together, with bone spurs forming at the edges. Over time the thumb bone can shift out of position. The arthritis cannot be cured, but it can be managed, and most people are able to relieve their pain and keep the thumb working.

Common symptoms include:

• Deep, aching pain at the base of the thumb that flares with pinching and gripping
• Swelling and tenderness at the base of the thumb on the wrist side
• Weaker grip and pinch as pain and joint instability set in
• Stiffness, most noticeable after rest
• A bony prominence as the joint shifts out of its normal position over time

Basal thumb arthritis is diagnosed from your symptoms, a focused exam of the thumb, and X-rays. The exam checks for tenderness at the joint base, swelling, and whether certain thumb movements reproduce the pain. X-rays show the narrowed joint space, bone spurs, and whether the thumb bone has shifted. An MRI is not usually needed.

Nearly everyone starts with nonsurgical care, which relieves pain and keeps the thumb working, often for years:

• A thumb spica splint to take stress off the joint, often the single most effective step
• Activity changes such as jar openers, wider-grip tools, and adjusted technique for pinch tasks
• Hand therapy to strengthen the muscles that support the joint
• Anti-inflammatory medication, oral or topical, for pain and inflammation
• A corticosteroid injection into the joint for temporary relief, which can be repeated

Surgery is considered when pain continues to limit daily activities despite months of these measures. The standard procedure removes the worn-out trapezium bone and uses a portion of a nearby tendon to cushion and hold the thumb in position.

• Thumb CMC arthroplastyHand & Wrist

For a fuller explanation, including anatomy, diagnosis, and the full range of treatment:

• Arthritis of the Thumb — AAOS OrthoInfo