Carpo metacarpal arthroplasty or CMC arthroplasty is a type of surgery in which a bone at the base of your thumb is replaced with an implant. The joint where your thumb meets your hand is called your carpometacarpal joint.

doctor examines the hand and thumb of a person who needs CMC arthroplasty Share on Pinterest

Carpal metacarpal arthroplasty, commonly called CMC arthroplasty, is a type of joint replacement surgery, an alternative to the traditional gold standard surgical treatment for carpometacarpal (CMC) arthritis, called trapeziectomy.

During a trapeziectomy, a surgeon removes the bone at the base of your wrist called the trapezium. The trapezium is a small bone, measuring less than an inch in greatest diameter. During CMC arthroplasty, the removed bone is replaced with an artificial implant.

CMC arthroplasty has been found to be up to 93% successful at 10-year follow-ups for new-generation implants.

People who have CMC arthroplasty are generally very satisfied with the results, and it’s less invasive than surgical options that involve tendon grafts. However, CMC arthroplasty generally involves more risk and is more expensive than a trapeziectomy.

Read on to learn everything you need to know about CMC arthroplasty, including benefits, risks, and what to expect during the procedure.

CMC arthroplasty was first performed in 1973. It involves replacing your trapezium with an implant to reduce pain when moving your thumb and preserve your thumb stability. Implants made up of metal and polyethylene currently seem to be the best option.

Many different types of surgery are used to treat problems with your CMC joint. Compared with alternative surgeries, some of the advantages of CMC arthroplasty are that it:

  • preserves your normal thumb length and alignment, unlike trapeziectomy
  • prevents instability of your wrist
  • prevents further joint degeneration
  • doesn’t require tendon grafts
  • has high levels of satisfaction
  • still provides the option for trapeziectomy if it fails

Language matters

You’ll notice we use the binary terms “males” and “females” in this article. While we realize this term may not match your gender experience, it’s the term used by the researchers whose data was cited.

We try to be as specific as possible when reporting on research participants and clinical findings.

Unfortunately, the studies and surveys referenced in this article didn’t report data on, or include, participants who were transgender, nonbinary, gender nonconforming, genderqueer, agender, or genderless.

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CMC arthroplasty is used to treat CMC joint arthritis. It may help you perform movements that are currently causing you pain, like grasping objects or making a pinching motion.

Arthritis in the CMC joint is very common. By age 50, it can be seen in 5.8% of males and 7.3% of females. These percentages rise to 33.1% of males and 39.0% of females by age 80.

CMC arthroplasty is often performed as an outpatient procedure, meaning that you’ll be able to go home the same day.

The procedure that a surgeon follows may look something like this:

  1. Before the operation, you’ll be given either general anesthetics to put you into a sleep-like state of nonfeeling, or local anesthetics, which will block the pain from your hand and arm. In some cases, you may be given both.
  2. Your surgeon will disinfect your hand and wrist before making an incision over the base of your thumb.
  3. The incision will be held open with devices called retractors, and the nerves and arteries will be pulled aside.
  4. Your surgeon will then remove your trapezium bone and replace it with an implant.
  5. The wounds will be sealed with stitches and covered with a soft dressing.

Your surgeon can give you specific instructions on how to prepare for your surgery. It’s important to tell the healthcare team about all medications and supplements you’re taking. They may ask you to stop taking some medications, such as anti-inflammatories, to reduce your risk of bleeding.

It’s important to arrange a way home in advance since you won’t be able to drive after your surgery.

You’ll remain in a recovery room after your procedure for monitoring and will likely be able to go home after an hour or two when you’ve recovered from anesthesia.

You’ll have a cast on your thumb for up to a month and will likely wear a splint for another 4 to 6 weeks, although recommendations on how long your thumb should be immobile vary widely.

You’ll also likely be referred to a physical or occupational therapist to help you regain strength in your thumb.

Try to avoid strenuous pinching for 6 weeks after surgery to allow your bone to fix to the implant.

You’ll likely have pain, weakness, and stiffness around your thumb during the recovery period, but most people have improved range of motion and strength compared with before their surgery.

One study has reported a success rate upward of 93% at 10-year follow-ups for new-generation implants.

The most common early risk is dislocation, with reported rates of 0% to 13%. Dislocation can also occur later due to wear on the implant or direct trauma.

Other risks can include:

CMC arthroplasty is more expensive than other surgical options and can cost upward of $4,000.

One clinic in Northern California lists its average price as $7,623.64.

Medicare and other insurance may cover some of the cost when deemed medically necessary.

Before trying surgery, a doctor will likely recommend conservative treatment options. These include:

If a doctor does recommend surgery, they may also recommend one of the following procedures:

  • Ligament reconstruction: A piece of a damaged ligament is replaced with a graft made from another piece of connective tissue.
  • Fusion (arthrodesis): Your trapezium bone is fused to the long, skinny bone at the base of your thumb with a plate or screw.
  • Trapeziectomy: Your trapezium bone is surgically removed.
  • Ligament reconstruction and tendon interposition: The damaged surfaces of the bones that make up the joint are replaced with a piece of soft tissue to keep the bones separated.

Here are some frequently asked questions people have about CMC arthroplasty.

What’s the most common treatment for CMC arthritis?

Trapeziectomy with ligament reconstruction and tendon interposition is the most common procedure for treating CMC arthritis.

How long does CMC surgery take?

In a 2020 study, researchers found that the average surgery time was 59 minutes among 53 people who received a technique called modified CMC suspension arthroplasty.

How long does my thumb need to be immobile after my procedure?

Recommendations on the immobilization period range from 2 to 12 weeks. In a 2022 study, researchers found no additional benefit to extended immobilization in a cast for more than 6 weeks.

CMC arthroplasty, also called carpal metacarpal arthroplasty, is a type of joint replacement for the thumb. It’s a treatment for arthritis in the thumb called CMC joint arthritis and an alternative to another commonly performed procedure called a trapeziectomy, in which the joint isn’t replaced.

Recovering from this procedure may take 6 weeks or longer, and people who have CMC arthroplasty are generally very satisfied with the results. CMC arthroplasty may be less invasive than other surgical options. However, this procedure may involve more risk than other types and is more expensive than a trapeziectomy.