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Painful Thumb May Be Disabling

by Thomas C. Howard III, MD

Pain at teh base of the thumb is a common complaint and a common source of disability. Many factors bring about the problem.

We call the joint a diarthrodial joint or a saddle joint. The stability of the joint is dependent upon the ligaments that hold the bones together. As one ages, the joint wears and the ligaments become loose. Trauma or injury also stretch the ligaments. When the ligaments become loose, the joint does not seat normally, and the joint surfaces wear prematurely. The premature degeneration of the joint is manifested by pain and deformity.

As the joint wears some people form spurs. This is nature's attempt to heal the damaged joint surfaces and also to provide stability. Pain, especially with pinching, is the primary complaint.

Some people do not form these large spurs. Their joint becomes more unstable. The base of the thumb gradually dislocates as it joins the wrist bones. This leads to a narrowing of the first web space. To compensate for this inadequacy in grip, then next joint down the thumb (the metacarpophalangeal joint) hyper-extends. While this allows the patient to maintain grasp, it causes the metacarpophalangeal joint of the thumb to wear and also facilitates the instability or partial dislocation of the base of the thumb.

Patients with this problem usually begin to experience discomfort at the base of the thumb. These symptoms can start at any age past skeletal maturity. More women have this problem than men. This probably has to do with the looseness of the ligaments.

Initial treatment can be as simple as avoiding the activities that cause the symptoms. Non-steroidal anti-inflammatories can be used. These medications include over-the-counter arthritis medications, as well as prescription medications. External support in the form of bracing is used to help people cope with the problem. These braces can be "out of the box," pre-fabricated braces. Custom braces to support the base of the thumb but not interfere with the wrist, can be made by physical therapists with doctor's orders.

A variety of surgical treatments are available. If the problem is severe enough and if no damage or destruction has been done to the bones, surgery can be done to tighten up the ligaments. Once bony destruction and spurring take place, surgery has to involve the joint surfaces themselves. In years past, artificial joints have been used. Silicone implants have been used, but these have fallen out of favor for a number of reasons and are not generally used any longer. Metal and polyethylene, similar to the materials used in knee and hip replacements have been used and are still available. Some metal implants that replace bone are also available.

There are two more common surgical procedures. One is a fusion of the base of the thumb. This provides stability and eliminates the motion that cause the pain. The healed fusion site is very durable.

The other common surgical procedure is to remove the arthritic bone or offending portions of those bones. This removal then leaves a space, which is then filled with biologic tissue. Specifically, a tendon is used. The tendon is placed in the space in such a fashion that it supports the base of the patient's thumb. If there is enough deformity, laxity, or disease in the metacarpophalangeal joint (the next joint past the base of the thumb), this joint may be stabilized. This stabilization can be done either by tightening the ligaments of the joint or by fusing that joint. Generally speaking, we do not fuse the base of the thumb and the metacarpophalangeal joint.

If the thumb problem is treated with surgery, there is usually a period of healing and immobilization from six to eight weeks. Pins are then removed. Rehabilitation takes about another two months. At that point, a patient is hopefully using this thumb for ordinary activities of daily living and gradually increasing his/her confidence in this "new" aspect of their thumb.