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Thumb Basal Joint Arthritis

Cartilage is the substance that lines the ends of our bones to allow smooth gliding surfaces for our joints. As the cartilage wears out and deteriorates, our bodies are not able to regenerate or replace the loss of joint cartilage. Eventually, this loss of cartilage leads to direct contact between the bones of the joint which produces symptoms of arthritis including joint stiffness, swelling, pain and deformity.

One of the most common areas of the hand and wrist to develop degenerative arthritis (also known as osteoarthritis) is the thumb basal joint. The base of the thumb joint is medically referred to as the thumb carpometacarpal (CMC) joint since the trapezium, a small carpal bone of the wrist, connects with the base of the thumb metacarpal bone to form the CMC joint. The basal joint of the thumb has a specialized saddle-shape that permits the thumb to rotate and move through a wide range of various motions.

Thumb CMC joint arthritis is more commonly seen in women over 40 years of age although it is also seen in men at a later age. With the exception of prior injuries such as a fracture or dislocation of the thumb CMC joint, it is believed that generalized joint laxity or joint looseness may predispose an individual to develop thumb basal joint arthritis. As women typically have more joint laxity compared to men, this relative increased sloppiness of the joint could explain the higher prevalence of thumb CMC joint arthritis seen in women at a younger age.

The most common complaint associated with base of thumb arthritis is pain. Pain is typically sharp and focal to the base of the thumb and is often aggravated by activities that require pinching and grasping with the thumb such as opening jars, turning keys, holding a golf club, and writing. As pain continues to worsen, performing simple activities of daily living can become very difficult. With progression to the final stages of arthritis, a secondary deformity at the first knuckle of the thumb (the metacarpophalangeal joint or MP joint) can develop. The thumb MP joint begins to bend back further to compensate for the improperly positioned thumb metacarpal and loss of motion at the CMC joint. This deformity is referred to as a swan-neck deformity which only further complicates functional use of the thumb.

Treatment

Mild basal joint thumb arthritis can respond to non-surgical treatment. Basic treatment measures include modification of activity with splinting, medications, and corticosteroid injections. Each of these may help alleviate pain or at least moderate the symptoms to prevent flares. The expectations and limitations of these treatment options will be discussed with your hand surgeon.

For those with advanced arthritis of the thumb basal joint or those who fail non-surgical treatment may be candidates for surgical reconstruction. A variety of surgical techniques are available that can successfully reduce or eliminate your pain and allow for improved functional use of the thumb. Surgical procedures include removal of arthritic bone with or without joint reconstruction (arthroplasty), joint replacement, or joint fusion. Dr. Katz will discuss the expectations of each and help choose the best option for you.