Review and Update on the Diagnosis and Treatment of Thumb ArthritisThe joint at the base of the thumb is called the thumb carpometacarpal (CMC) joint. It is a common site of osteoarthritis (OA) in the hand. The unique anatomy of this joint allows a wide range of movements.
Thick ligaments around the CMC keep it from moving too far and dislocating. Nine muscles surround the thumb CMC joint. These muscles work together to create a balance between stability and motion needed for movements such as thumb opposition and pinch.
Because CMC arthritis is so common, many older adults seek treatment for this problem. An accurate diagnosis is important in planning treatment. In this article, anatomy, diagnosis, and treatment are reviewed and updated for this condition.
X-rays are used to classify or stage thumb CMC arthritis. In stage I disease, the joint space is still normal. No changes are seen yet in the articular(joint) cartilage. In stage II disease, the joint space is starting to narrow. There is minimal damage to the joint or change in the joint contours (shape).
Stage III thumb CMC arthritis has noticeable narrowing of the joint space. There may be bone spurs, cysts, and sclerosis (hardening of the tissues). The joint begins to dislocate partially called subluxation. By the time stage IV occurs, the joint space has deteriorated. Complete dislocation is not uncommon.
Treatment is based more on the severity of patient symptoms than on the stage of disease. Conservative care with splinting, hand therapy, and steroid injection(s) are the first line of care. Surgery to preserve the joint may be needed in the earlier stages of this disease. Joint fusion or replacement is more likely in later stages.
The authors provide an in-depth review of surgical options. These include reconstruction, osteotomy, arthroscopy, arthrodesis (fusion), and arthroplasty (replacement). Osteotomy is the removal and repositioning of a wedge-shaped piece of bone. This procedure restores the anatomy and prevents dislocation.
Arthroscopy is used to look inside the joint and see what's going on. The surgeon can scrape the joint clean and/or remove any debris. Any rough spots in the synovium (lining of the joint) can be smoothed out. Heat can be used during arthroscopy to shrink (tighten up) the capsule.
Fusion is used to stabilize the joint when pain relief and strength are needed on-the-job. Younger adults in high-demand occupations may choose this treatment option. Rehab and recovery does involve a long period (three months) in a cast. Loss of motion in the joint may prevent some motions such as getting the hand flat or into a pocket.
Joint replacement of the CMC has not worked well so far. The implant wears out quickly because of the shear and compression forces across the joint. Researchers are working to find ways to improve the results.
For now, the standard surgical procedure for thumb CMC arthritis is to remove the trapezium bone. A folded piece of tendon is placed in the hole left by the bone removal. This operation is called ligament reconstruction and tendon interposition (LRTI).
The authors provide guidelines for the use of each of these treatment methods. Patient age, occupation, and severity of symptoms are used to guide the decision. The same criteria are used to identify the best surgical procedure to choose. Possible complications of each operation are also taken into consideration.
Ann E. Van Heest, MD, and Patricia Kallemeier, MD. Thumb Carpal Metacarpal Arthritis. In Journal of the American Academy of Orthopaedic Surgeons. March 2008. Vol. 16. No. 3. Pp. 140-151.
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