Basal joint arthritis
Arthritis at the small joint at the base of the thumb is a frequent condition, which causes annoying symptoms which can impair both strength and function of the hand. The condition occurs most commonly in women over the age of 40 and often affects both hands. Arthritis of the thumb is a form of osteoarthritis, also known as degenerative joint disease. It affects the basal joint at the base of the thumb, formed by the thumb metacarpal bone and a small wrist bone called the trapezium. The ends of these bones are covered with cartilage, which acts as a cushion and allows them to move freely. Arthritis destroys the cartilage, causing the joint to become painfully inflamed. Basal joint arthritis results in pain and restricts movement of the thumb across the palm. Far more common among women than men, it typically occurs after the age of forty. Both thumbs may be affected. The anatomy of the thumb explains why arthritis is so common. The thumb has two bones, the phalanges, which are connected to the longer first metacarpal bone in the hand. The first metacarpal connects to a small wrist bone - the trapezium - by forming a mobile joint known as the carpometacarpal or basilar joint of the thumb. The trapezium attaches to another wrist bone - the scaphoid or navicular - which forms a joint with the large forearm bone -- the radius - at the wrist. The joint at the base of the thumb is a very important joint - perhaps the most important joint when it comes to hand function. The unique shapes of the surfaces of the two bones that form this joint permit the thumb to have a wide range of motion. By using the small muscles arranged around the first metacarpal, the joint at the base of the thumb can rotate around a wide arc - in and out of the palm of the hand. It is this movement that allows the thumb to oppose the fingers for pinching and grasping activities. The stability of the carpometacarpal joint of the thumb relies on several small ligaments, which permit motion but retain a close relationship between the saddle-shaped joint surfaces. If the ligaments loosen enough to allow too much sliding of the joint surfaces, a wearing down of the joint cartilage may occur leading to arthritis. In time the joint surfaces will be destroyed and bony spurs or lumps may develop around the joint making it prominent and painful. Basal joint arthritis is caused by wear and tear on the joint at the base of the thumb, perhaps as the result of a fracture or injury. Repeated motions such as twisting, turning, or gripping objects with the thumb and fingers can worsen this condition. Inflammation may occur from this progressive joint destruction and pain results - particularly when the joint is under pressure during pinching and grasping activities. In advanced cases, there may be complete destruction of the joint, an inward collapse of the metacarpal and arthritic deterioration on all sides of the trapezium. Other joints may even be affected as they try and adapt to the abnormal position of the first metacarpal. Patients developing arthritis at the base of the thumb usually first notice pain associated with pinching activities such as turning keys or opening car doors. Tenderness in the fleshy thumb muscle over the first metacarpal or over the top of the basilar joint may also be experienced and there may be an aching discomfort at the base of the thumb following heavy use or with weather changes. As the disease progresses and more joint cartilage is lost, less stress on the thumb is necessary to produce pain. The patient will often avoid using the thumb for those activities that produce pain and over time this disuse can lead to weakness, muscle loss and a tendency to drop things. A thorough examination of the wrist and hand along with the patient's history and x-rays will disclose the status of the joint. Swelling at the base of the thumb due to inflammation or fluid in the joint is usually observed and the displaced position of the base of the first metacarpal will result in a firm prominence at the level of the joint. Tenderness to pressure by the examiners' finger will be localized over and around the joint. The examining physician may also use a diagnostic maneuver known as a "grind test" or "torque test" to determine if arthritis exists at the base joint of the thumb. In this test, the first metacarpal is grasped, pushed downward and rotated. Pain and a crunching or gritty sensation during this maneuver usually indicate that at least some degree of arthritis is present. X-rays will give the doctor an appreciation of the status of the joints at the base of the thumb and special views may be used to show the position of the first metacarpal and the integrity of the joint surfaces. But regardless of the appearance of the x-rays it is the patient's symptoms and the effect that the condition has on the ability to perform daily tasks that will best determine what, if any, treatment should be used. In the early stages of arthritis at the base of the thumb, anti-inflammatory medication, cortisone injections into the joint, or splinting of the wrist and thumb may be helpful. Splints will put the thumb at rest and prevent the arthritic joint from moving. This may provide transient relief from the annoying symptoms of this condition. It is important that the splints used for this condition extend well up on the thumb. Most commercially available, "drug-store" wrist splints leave the thumb free and may actually worsen the discomfort at the base joint. When these conservative methods of treatment are no longer beneficial to the patient, surgery may be warranted. Arthroscopic debridement of the joint followed by the injection of viscosupplement (lubricant) has been used with success by some. The advantage of this procedure is that it is minimally invasive compared with other surgical procedures. The most important goal of surgery is to eliminate the pain at the base joint of the thumb, by creating a new joint. In some instances, surgery is necessary to improve the position of the thumb its range of motion and to improve strength for pinching and grasping. Surgery is accomplished by one of several techniques, which remove the destroyed joint surfaces, and create a substitute joint. The procedure is referred to as an arthroplasty. Surgery for arthritis at the base of the thumb may be performed in several ways according to the personal preference of the surgeon. It may be either an in-patient or outpatient procedure under regional block or general anesthesia. In this procedure one or more incisions are made in the forearm and over the arthritic joint. In general, all techniques involve removing all or part of the small wrist bone - the trapezium. In most cases, the space created by removing the trapezium will be filled with tendon material, and most surgeons use all or part of an adjacent tendon to suspend and stabilize the base of the first metacarpal so that the reconstructed thumb will regain strength. Following surgery, the wrist and thumb are immobilized in a large bandage with a rigid splint to protect the thumb and prevent movement. The fingers are left free and the tip of the thumb is also permitted to move. Elevation of the hand for several days as well as vigorous finger motion is important to prevent swelling and stiffness. It is common for patients to experience discomfort during the initial phases of rehabilitation following surgery for arthritis at the base of the thumb. As the exercises stretch the structures used to stabilize the first metacarpal, the patient may have discomfort. There may also be some mild inflammation around the surgical site. However this gradually resolves and, by three to six months, most patients experience complete, or near-complete pain relief along with recovery of a satisfactory range of motion. Strength recovery may take up to one year depending on the amount of weakness prior to surgery and how vigorously strengthening exercises are continued. Although surgery for arthritis at the base of the thumb is usually without any significant problems, there occasionally may be unforeseen complications associated with anesthesia, including respiratory or cardiac malfunction. The surgery itself may be complicated by anatomic abnormalities or accidental injury to adjacent tissue structures such as tendons, nerves or blood vessels. Rarely, the post-operative discomfort and or thumb stiffness may be greater than expected and require a longer recovery time. A condition known as reflex sympathetic dystrophy may occur in a few individuals and result in generalized pain, swelling and stiffness of the entire hand. Wound infection, although very infrequent, may occur after any surgery and may hamper a positive result. Although the speed of recovery is variable for different patients following this surgery, most recover excellent thumb motion, function and strength within a year of surgery. Pain relief is highly predictable and almost all patients are pleased with their surgery.
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