Most activities that involve grasping or pinching are possible because of the thumb's remarkable range of motion. However, dexterity comes at a price - an increased risk of osteoarthritis in the first carpometacarpal (CMC) joint, where the thumb meets the trapezium bone in the wrist. Sometimes the joint becomes so damaged that surgery is necessary.
Problems often start when the thick ligaments that hold the joint together loosen, allowing it to slip out of place. Over time, the articular cartilage that cushions the ends of the bones wears away, causing pain and limiting movement. Rheumatoid arthritis (RA) and other forms of inflammatory arthritis can also damage the first CMC joint - also known as the trapeziometacarpal joint (TMC).
Several surgical options are available, and the best approach depends on the stage of the disease and the severity of symptoms. Broadly speaking, most thumb surgeries remove some or all of the arthritic bone and use various methods to stabilize the joint.
This procedure stabilizes the CMC joint by removing a portion of the damaged ligament and replacing it with a piece of the patient's wrist flexor tendon.
In use for more than 40 years, LRTI is the most commonly performed surgery for thumb arthritis. The arthritic joint surfaces are removed and replaced with a cushion of tissue that keeps the bones separated. To accomplish this, surgeons remove all or part of the trapezium bone in the wrist.
A nearby tendon is detached at one end and then passed through a hole drilled in the thumb metacarpal. The remaining tendon is rolled like an anchovy and placed into space where the bone was removed. Surgeons can also use artificial "anchovies" that eliminate the need to move a tendon.
In this simple, somewhat controversial procedure, surgeons remove the trapezium bone in the wrist and, with a wire, temporarily immobilize the thumb. The wire is removed six weeks later. The idea is that, without the constant friction caused in part by the trapezium, the body can heal itself.
Like hip or knee replacement, this procedure removes all or part of the damaged thumb joint and replaces it with an artificial implant. Early implants were made of silicone. Surgeons now use metal or pyrocarbon prostheses and cushioning synthetic spacers that sit between the bones.
Arthrodesis eliminates pain by fusing the bones in the joint together. Surgeons create a socket by hollowing out the thumb's metacarpal bone and then shaping the trapezium into a cone that fits inside the socket. A metal pin holds bones together to maintain proper alignment and prevent movement while the bones fuse.
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