The carpometacarpal (CMC) joint at the base of the thumb is where the thumb’s metacarpal bone meets the trapezium bone of the wrist. This joint is essential for the thumb’s ability to swivel, pivot, and perform pinching motions necessary for daily activities like gripping and opening jars. Thumb arthritis, or CMC joint osteoarthritis, is a common condition where the protective cartilage wears away, causing bones to rub against each other, leading to pain, swelling, and loss of strength. When conservative treatments such as splinting, anti-inflammatory medications, and steroid injections no longer provide adequate relief, surgery becomes necessary to relieve persistent pain and restore function. This article will explore the surgical options available for CMC arthritis, detailing their mechanics, outcomes, and the factors that influence which procedure is recommended.
Trapeziectomy and Ligament Reconstruction
Trapeziectomy is the most frequently performed surgical procedure for advanced basal joint arthritis. This technique involves the complete surgical removal of the trapezium bone, which articulates with the thumb metacarpal. Removing the damaged bone eliminates the source of bone-on-bone friction, leading to effective and long-lasting pain relief for most patients.
The resulting space created by the removal of the trapezium can allow the thumb’s metacarpal bone to migrate downward, potentially leading to instability. To stabilize the joint and prevent this collapse, the procedure is often combined with Ligament Reconstruction and Tendon Interposition (LRTI). LRTI uses a portion of a local tendon, such as the flexor carpi radialis (FCR). This tendon is threaded through a hole drilled in the thumb metacarpal for stabilization. The remaining piece is placed into the empty space, acting as a cushion or “spacer” to maintain joint height.
The functional benefit of trapeziectomy with LRTI is a significant reduction in pain. Patients should expect a lengthy recovery, with the thumb typically immobilized in a splint or cast for up to four weeks post-surgery. Physical therapy starts around four weeks to restore motion, but strength continues to improve for up to a year. While this procedure offers excellent pain relief, some studies indicate a potential for a slight, permanent loss of pinch or grip strength compared to other surgical options.
Joint Fusion and Arthroplasty
While trapeziectomy addresses the arthritic joint by removing the damaged bone, Arthrodesis (joint fusion) and Arthroplasty (joint replacement) offer alternative approaches to stabilizing or replacing the joint surfaces. Arthrodesis locks the first metacarpal bone and the trapezium together, eliminating motion at the CMC joint. The surgeon prepares the bone surfaces and secures them with pins, screws, or plates in a position that optimizes function for pinching and gripping.
The main advantage of fusion is that it provides maximum joint stability and preserves or significantly improves grip and pinch strength, which can be higher than the strength achieved after trapeziectomy. The trade-off for this strength and stability is the complete loss of motion at the fused joint, which requires other thumb and hand joints to compensate for movement. For patients whose work involves heavy, repetitive gripping or sustained high-load activities, the stability of fusion is considered a significant benefit over the risk of instability associated with bone removal procedures.
Arthroplasty replaces the damaged joint surfaces with an artificial implant or spacer. These implants are designed to replace the trapezium, often using metal or pyrocarbon components, which aim to preserve the natural motion of the joint. The goal is to maintain the range of motion while eliminating the painful bone-on-bone contact, potentially offering a quicker functional recovery than bone removal procedures.
The long-term durability of joint replacement implants remains a concern, as they carry a risk of wear, loosening, or dislocation, particularly with heavy use. Some specialized arthroplasty techniques, like a simple trapeziectomy followed by the insertion of a soft tissue or synthetic spacer, are less invasive. Selecting between the different types of arthroplasty depends on the patient’s activity level, with less active individuals sometimes being better candidates for metal-on-plastic prostheses.
Factors Guiding Surgical Selection
Determining the best surgery for thumb arthritis is a clinical decision tailored to the individual patient. The choice hinges on the severity of the arthritis, the patient’s physical demands, age, and personal preferences regarding stability versus range of motion. Surgeons assess the stage of arthritis using X-rays, as advanced stages with significant joint collapse often steer the decision toward procedures involving bone removal or replacement.
A patient’s occupation and activity level are primary considerations when comparing trapeziectomy against fusion. For a younger, active individual who engages in heavy labor, weightlifting, or requires maximum grip strength, arthrodesis (fusion) is often the preferred recommendation due to the superior stability and strength it provides. In contrast, trapeziectomy with LRTI is widely considered the gold standard for most patients, particularly older individuals with lower functional demands, where the main priority is reliable pain relief and maintaining a good range of motion.
Patient preference regarding motion is also influential in the final decision. Patients who prioritize maintaining a near-normal range of motion and dexterity are generally better suited for trapeziectomy or joint arthroplasty. Conversely, those who prioritize a strong, stable thumb for forceful activities, accepting a loss of motion, are better candidates for joint fusion. Ultimately, the surgeon must integrate the objective evidence of the disease with the patient’s lifestyle and goals to select the most appropriate treatment option.