Overview
The joint at the base of the thumb is called the carpometacarpal (CMC) joint. It is shaped like a saddle, which gives the thumb its huge range of motion. That same shape makes it one of the most common places in the hand to get arthritis. Worn cartilage causes pain with pinch, grip, and fine hand work. Over time the base of the thumb drops in toward the palm.
How the Procedure Works
We remove the trapezium, the small wrist bone the thumb sits on, through a small incision on the back of the thumb. We take all of it. Leaving part behind reliably brings the symptoms back as the remnant wears down. Once the space is clear, we hold the thumb bone in place with a small implant instead of one of your own tendons. A strong surgical stitch is passed through the thumb bone and anchored to the neighboring index bone with small buttons. This holds the thumb in position so pinch strength is preserved while the tissue around it heals.
Because no tendon is taken, motion generally comes back faster. Some people have temporary weakness during healing. Long-term grip and pinch strength consistently return to useful levels. That is the outcome that matters for the tasks that drove you to surgery.
When to Consider Thumb CMC Arthroplasty
We generally offer thumb CMC arthroplasty when symptoms, imaging, and a full course of non-surgical care all point to surgery as the next step. The typical picture includes:
Symptomatic basal-thumb arthritis
Pain at the base of the thumb with pinch and grip, plus joint-space narrowing on X-ray.
Failure of conservative care
A thumb (spica) splint, activity changes, therapy, and injections that have not given lasting relief.
Functional limitation
Trouble with tasks that need pinch: opening jars, buttoning, writing, keys.
Treats: Thumb CMC Arthritis
Physicians Who Perform Thumb CMC Arthroplasty
Risks & Why We Still Recommend It
Every operation carries risk. This procedure is offered because the condition, when left untreated, can cause daily pain at the base of the thumb, reduced pinch strength, and gradual loss of grip. The decision to proceed weighs the risks of surgery against the limitations the condition places on daily function. Surgery does not remove risk; it addresses a problem that is otherwise progressive. Whether it is appropriate is determined for each patient in consultation with the surgeon.
The risks we discuss with you before thumb CMC arthroplasty include:
- bleeding and infection
- anesthesia risk
- stiffness
- irritation of a small skin nerve (the superficial radial nerve), causing numbness on the back of the thumb
- some loss of thumb height (subsidence), usually well tolerated
- ongoing pain if nearby joints are also affected
- scar tenderness
We proceed when there is advanced arthritis at the base of the thumb that has not improved with splinting and injections. If this operation is not right for you, we will not recommend it.
Frequently Asked
questions we hear in clinicWhy does the base of the thumb get arthritis so often?
The CMC joint is shaped like a saddle, which gives the thumb its huge range of motion. That same shape makes it one of the most common places in the hand to get arthritis. Worn cartilage causes pain with pinch, grip, and fine hand work, and over time the base of the thumb drops in toward the palm.
What exactly is removed?
The trapezium, the small wrist bone the thumb sits on, through a small incision on the back of the thumb. We take all of it, because leaving part behind reliably brings the symptoms back as the remnant wears down.
What holds my thumb in place afterward?
A small implant instead of one of your own tendons. A strong surgical stitch is passed through the thumb bone and anchored to the neighboring index bone with small buttons. This holds the thumb in position so pinch strength is preserved while the tissue around it heals.
Will my pinch and grip strength come back?
Some people have temporary weakness during healing, but long-term grip and pinch strength consistently return to useful levels. Because no tendon is taken, motion generally comes back faster.
When is surgery the right step?
When symptoms, imaging, and a full course of non-surgical care all point the same way: pain at the base of the thumb with pinch and grip, joint-space narrowing on X-ray, and no lasting relief from a thumb (spica) splint, activity changes, therapy, and injections.
What are the main risks?
Bleeding and infection, anesthesia risk, stiffness, irritation of a small skin nerve causing numbness on the back of the thumb, some loss of thumb height (usually well tolerated), ongoing pain if nearby joints are also affected, and scar tenderness.
Further Reading
External patient-education references and related OSI pages for additional background: