Thumb CMC Joint Arthroplasty

Thumb arthroplasty is a surgical procedure to treat arthritis affecting the joint at the base of the thumb. This surgery helps restore mobility and function to the thumb.

Disease Overview

The thumb is an important part of the hand as it helps to perform a wide range of movements such as pinching and grasping, which are used in daily activities. These movements are enabled by bones that run from the tip of the thumb to the wrist. The thumb articulates with a bone in the palm called the first metacarpal, which in turn articulates with a wrist bone called the trapezium. The joint between the first metacarpal and the trapezium is called the carpometacarpal (CMC) joint. Each joint is lined by articular cartilage, which helps in smooth, frictionless movement. Loss of cartilage due to wear and tear causes painful rubbing of the bones. This condition is called osteoarthritis, and is associated with pain, swelling and stiffness. Osteoarthritis commonly affects the CMC joint of the thumb, limiting its movement. Thumb osteoarthritis is commonly seen in women over the age of 40 and those with a previous history of trauma to the joint.

Indications

Thumb arthritis may be initially treated non-surgically with ice applications, anti-inflammatory medications, splints, and steroid injections. However, because arthritis is a progressive condition, the symptoms of pain, swelling and loss of function gradually become worse and non-surgical options may no longer work. This is when thumb arthroplasty surgery is indicated.

Surgical procedure

Thumb Arthroplasty Surgery may be performed under general or local anesthesia.

• Your surgeon makes an incision down the back of the thumb to the wrist exposing the CMC joint with care taken to avoid damage to adjacent nerves.
• The carpometacarpal joint is exposed and the capsule is opened.
• The trapezium bone is identified and excised completely or partially.
• A tendon near the thumb is used to stabilize the base of the first metacarpal bone. This is done either by rolling up the tendon and using it in the defect or by creating a tunnel (ligament reconstruction)
• A K-wire is placed between the thumb metacarpal and index metacarpal or trapezoid to support the thumb. This will remain in place for 4 weeks postoperatively while in the cast, after which it is easily removed.
• The capsule and soft structures are sutured to cover the joint.

Post-Operative Care

Following surgery, your thumb and wrist are placed in a bandage and supported by a splint leaving your fingers as well as the tip of your thumb free to move. You are advised to keep the hand elevated and apply ice to minimize pain and swelling. Movement of the hand is encouraged in the splint. The area needs to be kept dry. The splint will be replaced by a cast which is worn for three weeks. After one month, the patient may start using the hand for daily functions protected in a hand based CMC splint. This is followed by rehabilitation exercises initially to control pain and swelling and later to restore strength and movement. You can resume your daily activities in 3 to 6 months.

Risks and Complications

As with all surgical techniques thumb arthroplasty may be associated with certain risks and complications including:

• Infection
• Bleeding
• Nerve injury
• Stiffness