The short answer
Thumb CMC (basal joint) arthritis is cartilage wear where the thumb meets the wrist, causing pain and weakness at the base of the thumb with pinching, gripping, and twisting motions like opening jars. Non-surgical care includes a supportive brace, hand therapy, anti-inflammatories, and ultrasound-guided cortisone or PRP injections.
Medically reviewed by Marc Gruner, DO, MBA, RMSK
Sports medicine physician, Mayo Clinic fellowship. Last reviewed June 2026
Overview
The basal (carpometacarpal, or CMC) joint at the base of the thumb is one of the most mobile — and most arthritis-prone — joints in the hand. As its cartilage wears, pinching and gripping become painful and weak, and the joint may look enlarged over time.
Because the thumb drives so much hand function, Dr. Gruner emphasizes joint protection and a supportive brace, hand therapy to strengthen the surrounding muscles, and precise ultrasound-guided cortisone or PRP injections into this small joint, keeping reconstructive surgery as a later option.
Common symptoms
- Pain at the base of the thumb
- Weakness with pinching and gripping
- Pain opening jars or turning keys
- Aching after hand-intensive tasks
What to expect at your visit
- 1.
A focused conversation
Dr. Gruner reviews your history, prior imaging, and goals — what you want to get back to doing.
- 2.
Point-of-care ultrasound
When useful, a diagnostic musculoskeletal ultrasound evaluates the injury in real time, with no radiation.
- 3.
A clear, individualized plan
You leave understanding the diagnosis, the non-surgical options, and the expected timeline — in plain language.
Frequently asked questions
- What helps thumb arthritis pain?
- A supportive CMC brace, joint-protection strategies, hand therapy, anti-inflammatories, and ultrasound-guided cortisone or PRP injections often control symptoms well. Surgery is considered only when these measures stop working.