Thumb CMC Arthroplasty

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.

Before, advanced thumb CMC arthritis
Preoperative PA X-ray zoomed on the thumb CMC joint, joint space narrowing, sclerosis, and dorsal subluxation. Preoperative oblique X-ray zoomed on the thumb CMC joint, osteophytes and loss of joint space at the base of the thumb.
After, thumb CMC arthroplasty
Postoperative X-ray zoomed on the reconstructed thumb base, trapezium removed and a small suture-button implant suspending the thumb metacarpal from the index metacarpal.
Thumb CMC arthroplasty, before and after. The before X-rays (top) show advanced arthritis at the base of the thumb. The cartilage is worn, the joint space is narrowed, and the long bone of the thumb (the metacarpal) has slipped out of position. The after X-ray (bottom) shows the rebuilt base. The trapezium has been removed. A small suture-and-button implant, anchored to the neighboring index bone, now holds the thumb bone in place instead of one of your own tendons. Patient imaging de-identified per HIPAA (45 CFR §164.514)

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:

  1. Symptomatic basal-thumb arthritis

    Pain at the base of the thumb with pinch and grip, plus joint-space narrowing on X-ray.

  2. Failure of conservative care

    A thumb (spica) splint, activity changes, therapy, and injections that have not given lasting relief.

  3. Functional limitation

    Trouble with tasks that need pinch: opening jars, buttoning, writing, keys.

Treats: Thumb CMC Arthritis

Physicians Who Perform Thumb CMC Arthroplasty

Michael S. Vrana, M.D.

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 clinic
Why 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: