Carpometacarpal (CMC) Joint Arthroplasty: Everything You Need to Know

thumb and hand in cast

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Carpometacarpal joint arthroplasty is a surgical procedure in which the trapezium, one of the carpal bones of the wrist that forms part of the thumb joint, is removed and replaced with an implant. This procedure can help manage symptoms of thumb arthritis by decreasing pain and improving use of the thumb for gripping, pinching, and grasping when conservative methods fail to relieve arthritis symptoms.

This article will explain how to prepare for carpometacarpal joint arthroplasty and what to expect. 

What Is CMC Joint Arthroplasty?

Joint arthroplasty, or joint replacement surgery, is a surgical procedure in which a portion of damaged and inflamed bone is removed and replaced with metal implants in order to help relieve pain and improve physical functioning for patients with arthritis. While joint arthroplasty is commonly performed in large joints like the hips, knees, and shoulders, joint arthroplasty can also be performed on the thumb joint.

Thumb arthritis, also known as carpometacarpal joint osteoarthritis, occurs at the carpometacarpal (CMC) joint at the base of the thumb, between the metacarpal bone and the trapezium. The force to the joint during gripping, pinching, and grasping movements and the decreased strength of supporting ligaments that occur with aging often cause degeneration of the thumb joint over time. Because the thumb is a very mobile joint, it lacks the stability to withstand repetitive stress and easily wears down over time.

CMC joint arthroplasty typically involves a trapeziectomy, a surgical procedure in which the trapezium bone is removed from the wrist. Once the trapezium is removed, a tendon graft or implant, made from silicone or metal, is then inserted into the missing space to complete the arthroplasty.

Potential Risks

Most people recover well after undergoing CMC joint arthroplasty. Potential risks associated with surgery of the hand and wrist include:

Additional risks associated with joint replacement surgery for the CMC joint of the thumb include:

  • Tendon tethering: Tendons that are used for grafting procedures to make implants can tether, causing the tendon to develop scarring and adhesions. This will cause the tendon to stick to its tendon sheath, which prevents it from gliding smoothly and functioning properly
  • Subsidence: With joint implants, the body can produce an inflammatory reaction in response to the new foreign substance, causing the implant to gradually sink down into surrounding bone

Consult with your healthcare provider about the possible risks of CMC joint arthroplasty to determine if it is an appropriate option for you given your age, current health status, and medical history.

Purpose of CMC Joint Arthroplasty

CMC joint arthroplasty is commonly performed for arthritis of the thumb that does not improve with conservative treatment options, including:

  • Activity modification: Resting and avoiding painful activities, especially repetitive gripping, grasping, and pinching, can reduce inflammation in the thumb to promote recovery.
  • Adaptive equipment: Using special tools to help with tasks like opening jars and using utensils can help reduce strain and inflammation of the thumb joint.
  • Medications: Anti-inflammatory and pain-relieving medications are often prescribed to help manage symptoms.
  • Cortisone injections: A healthcare provider may inject cortisone into your thumb to locally decrease pain and inflammation.
  • Bracing or splinting: A thumb brace or splint can be used to externally support the thumb joint to decrease thumb strain while using your hands to complete everyday activities.
  • Physical therapy or occupational therapy: Physical or occupational therapy can help strengthen the hand and wrist muscles to support the carpometacarpal joint of the thumb to improve hand use and function. Treatment modalities can also be applied to help with pain relief.

How to Prepare

The surgical team will provide you with more detailed instructions on what you will need to do in the days and hours before your surgery. It is recommended that you stay active, eat a healthy diet, and stop smoking prior to any operation to promote optimal healing and a smooth recovery.

You may need to stop taking certain medications in the days leading up to the surgery to prevent excess bleeding or interaction with anesthesia during the surgery. Always consult with your healthcare provider about all prescriptions, over-the-counter (OTC) medications, and supplements that you are taking for your safety.

CMC joint arthroplasty is often performed as an outpatient surgical procedure at either a hospital or outpatient surgical center. You will likely go home the day of your surgery. You will not be allowed to drive to or from the hospital before or after your surgery, so make arrangements for a friend or family member to provide transportation for you.

What to Expect

On the day of your CMC joint arthroplasty, you will be taken to a pre-op room where you will be asked to change into a gown. You will undergo a brief physical examination and answer questions about your medical history from the surgical team. 

You will be taken into the operating room, where you will be given anesthesia. The surgery will either be performed under general anesthesia, in which you are asleep during the operation, or local anesthesia, which involves numbing just your arm so that you do not feel anything during the surgery.

The skin of your hand and thumb will be sterilized with an antiseptic solution to kill bacteria and prevent infection before an incision is made.

During the Surgery

Your surgeon will make an incision along the top of the metacarpal bone of the thumb and use metal retractors to hold the incision open. The radial nerve and radial artery will carefully be moved out of the way with the retractors to fully expose the underlying bones.

The procedure for your CMC joint arthroplasty will depend on what type of implant is used to replace the trapezium bone. Implants can either be made from metal or silicone, or created from a tendon graft from one of your wrist muscles in a procedure called ligament reconstruction and tendon interposition (LRTI).

For an LRTI procedure, a trapeziectomy is performed first to remove your trapezium bone. The tendon of the flexor carpi radialis muscle of your wrist will also be cut and surgically reattached to the metacarpal bone of the thumb. Part of the cut tendon will be used to reconstruct the palmar oblique ligament that connected the metacarpal bone of the thumb to the trapezium.

The remaining portion of the tendon is then folded eight to 10 times, sewn together like an accordion, and inserted into the space where your trapezium was. As you heal, the tendon will toughen into scar tissue and provide added stability to replace the missing bone from the carpometacarpal joint.

Silicone or Metal Implants

If a tendon graft is not used for your CMC joint arthroplasty, a silicone or metal implant will be used instead. A silicone implant can be inserted into the space where the trapezium was removed following a trapeziectomy, and the joint capsule will be tightly sewn shut.

Silicone implants for CMC joint arthroplasty were primarily used at first but have been associated with the risk of joint dislocation, the formation of cysts (fluid-filled sacs), and synovitis, or inflammation and swelling of the synovial membrane that lines the CMC joint.

If a metal implant is used, a trapeziectomy will not be performed and the trapezium will stay in place. Instead, a metal implant will be inserted into the metacarpal bone of the thumb that joins the trapezium to form the CMC joint. This procedure is called a saddle hemiarthroplasty.

An incision into the CMC joint capsule will be made and a bone saw will be used to cut perpendicularly into the bone of the thumb’s metacarpal. A 6- to 8-millimeter portion of the bone is then removed. The trapezium may also be reshaped or contoured to improve the shape of the bone and mobility of the joint surface.

A metal implant is then inserted into the space where the portion of the metacarpal bone was removed and hammered into the remaining metacarpal bone before the joint capsule is tightly sewn shut.

After the Surgery

After your CMC joint arthroplasty, you will be brought to a recovery room where your vital signs will be monitored as the effects of the anesthesia begin to wear off. You will typically be able to go home one or two hours after the operation once you are stabilized.

Recovery

After your surgery, your thumb will be placed in a cast for three to four weeks. When the cast is removed you will be given a plastic splint to wear for four to six weeks. The plastic splint should be worn at all times. However, it can be removed when performing specific exercises to strengthen your thumb. You're typically weaned off the splint between six weeks and three months after surgery.

You will be referred to either a physical therapist or occupational therapist, who will devise a plan of care and provide you with exercises to restore the range of motion of your thumb and hand. It can take between six and eight weeks to regain full movement in your thumb. 

What You Can Do to Manage Pain and Swelling

You may experience pain and discomfort in your thumb after the surgery. Your healthcare provider will prescribe pain medication to help manage your symptoms. Elevating your hand will help decrease swelling, which will result in less pain, increased range of motion, and quicker recovery time.

Wound Care

Your surgeon will give you specific instructions on how to wash around your incision site once your cast is removed. Avoid applying lotions, creams, or ointments directly to the area unless specifically instructed to do so by your healthcare provider.

If you develop a fever or if the surgical site becomes red, hot, or swollen, contact your healthcare provider immediately because these are signs that you may have an infection.

Coping with Recovery

It is important to follow all instructions from your surgeon and physical therapist or occupational therapist to promote optimal healing and recovery from CMC joint arthroplasty.

Recommendations for optimal recovery include:

  • Getting enough sleep at night, at least seven to eight hours
  • Eating a healthy diet and managing a healthy weight
  • Staying hydrated
  • Maintaining a positive attitude and learning how to cope with and manage stress
  • Exercising as prescribed by your physical or occupational therapist
  • Staying active and limiting the amount of time you spend sitting each day
  • Wearing your splint at all times and according to your healthcare provider’s instructions, with the exception of removing it to clean the incision and perform exercises

Lifestyle Adjustments

It will take some time before you can regain full use of your thumb and hand after the surgery. Make sure that you:

  • Elevate your hand when sitting or lying down to reduce pain and swelling
  • Do not push yourself to do too much too soon—be careful when lifting, pushing, and pulling
  • Attend all of your regularly scheduled therapy sessions, and follow up with a home exercise program

Adaptive tools like specialized scissors, jar openers, button hooks, key turners, and pen grips can also be used to help you with tasks that require fine motor movement and dexterity of your hands that may be difficult after surgery.

Summary

CMC joint arthroplasty is a surgical procedure used to replace the trapezium bone of the thumb joint with a tendon graft, or a silicone or metal implant to treat carpometacarpal joint osteoarthritis after conservative treatments fail to relieve symptoms.

The surgery is typically performed on an outpatient basis, and you will go home the same day. After surgery, your thumb will be placed in a cast for three to four weeks, followed by a plastic splint for four to six weeks. Typically, it takes between six and eight weeks to regain full movement in your thumb. 

A Word From Verywell

Recovery from CMC joint arthroplasty can vary in length, from several weeks to several months. It is crucial that you follow the appropriate precautions after your surgery, including limiting your hand use and wearing a splint. You can progress to more intense activities when you are cleared by your healthcare provider or physical or occupational therapist.

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8 Sources
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