You use your thumbs every time you do anything with your hands so it is easy to see why the joint where the thumb attaches to the hand can suffer from wear and tear. This carpometacarpal (CMC) joint is designed to give the thumb its rather large range of motion, but the downside is that the joint suffers a lot of stress over the years. The ligaments around the joint provide stability so there is more uniform pressure on the joint. The basilar thumb joint, or thumb carpometacarpal (CMC) joint, has significant pressure across it with normal hand use. The joint can become unstable from ligament stretching or weakening with normal aging. Over time, the combination of instability and high pressure across the joint, leads to arthritis of the thumb CMC joint.
Smooth cartilage covers the ends of the bones. It enables the bones to glide easily in the joint. Without it, bones rub against each other, causing friction and damage to the bones and the joint. Osteoarthritis occurs when the cartilage begins to wear away. The joint at the base of the thumb, near the wrist and at the fleshy part of the thumb, enables the thumb to swivel, pivot, and pinch so that you can grip things in your hand.
Arthritis at the base of the thumb is the most common place for arthritis in the hand and can be very disabling. The thumb is a small but strong structure that is essential in performing tasks such as turning doorknobs or opening jars. Most movements of the thumb involve the joint connecting the wrist and the base of the thumb, known as the carpometacarpal (CMC) joint. Arthritis of the base of the thumb is more common in women than in men, and usually occurs after 40 years of age. Prior fractures or other injuries to the joint may increase the likelihood of developing this condition.
Arthritis causes pain in the base of the thumb when gripping, grasping or pinching an object. Some people may also experience pain during sleep or while the thumb is not in use. Other common signs of thumb arthritis include:
- Swelling and tenderness at the base of the thumb
- Stiffness with loss of thumb movement
- An aching discomfort after prolonged use
- Pain with activities that involve gripping or pinching, such as turning a key, opening a door, or snapping your fingers
- An enlarged, “out-of-joint” appearance
- Development of a bony prominence or bump over the joint
- Loss of strength in gripping or pinching activities
Diagnosis of thumb arthritis is based on the history, physical examination. One of the tests used during the examination involves holding the joint firmly while moving the thumb. If pain or a gritty feeling results, or if a grinding sound (crepitus) can be heard, the bones are rubbing directly against each other. You will also be examined for an enlarged joint that appears to stick out more than the other hand, as well as for range of motion loss. X-rays will be obtained to see how advanced the joint damage is. It may show narrowing of the joint space, bone spurs and sometimes subluxation (slippage) of the joint.
Non-surgical Treatment Options
The treatment of degenerative arthritis of the CMC joint of the thumb is based on the severity of symptoms. The goals of treatment are to relieve pain, decrease disability, and prevent deformity. Treatment can be divided into the nonsurgical means to control the symptoms and the surgical procedures that are available to treat the condition. The treatment of degenerative arthritis of the CMC joint of the thumb is based on the severity of symptoms. The goals of treatment are to relieve pain, decrease disability, and prevent deformity. Treatment can be divided into the nonsurgical means to control the symptoms and the surgical procedures that are available to treat the condition.
In its early stages, arthritis at the base of the thumb will respond to nonsurgical treatment. Non-surgical treatment options for thumb arthritis include the use of oral medications such as an NSAID (Non-Steroidal anti-inflammatory) or the injection of corticosteroid into the CMC joint. These injections can provide relief for several months or more and allow the patient to resume normal activities. Hand therapy for range-of-motion and stretching exercises are prescribed to improve your thumb motion. Strengthening exercises for the arm and hand help steady the hand and protect the thumb joint from shock and stress. Strengthening improves joint stability and prevents deformity and/or dislocation. Your Certified Hand Therapist will go over tips on how you can get your tasks done with less strain on the joint.
Surgical Treatment Options
Surgery can be performed on an outpatient basis under general anesthesia with the patient going home the same day. The reconstruction of the thumb’s basal joint is a procedure which requires removal of the diseased bone and substituting a tendon in its place. The trapezium is removed during the surgery and a tendon replacement cushion is placed in its spot. The ligament stabilizing the joint is reconstructed to keep the remaining bones well aligned. This helps hold the thumb in place and keeps the space between the bones from collapsing. This surgery can be combined with other hand procedures such as carpal tunnel release or trigger finger release if the patient also has one of those conditions.
The thumb and wrist are protected in a splint or removable cast after surgery for a total of 4 weeks. Hand therapy is started to help with increasing range of motion, getting strength back, and to regain function. You may feel some discomfort during the initial stages of the rehabilitation program, but this will diminish over time. Full recovery from surgery takes several months. Most patients are able to resume normal activities. The length of the Hand therapy is three months and then you are on a home exercise program. It may take a year or more to get all your grip strength back but you should able to do most or all activities of daily living by three to four months.