Introduction
The base of the thumb features the most mobile joint in the hand, enabling a wide range of movements such as lifting, rotating, and aligning with the fingers. We engage our thumbs hundreds of times daily, using them for tasks that require gripping, like using a hammer or holding a glass. They also stabilize our grip to allow for fine manipulations, such as counting change or writing. Over time, frequent movement and pressure can lead to wear and tear, potentially resulting in joint degeneration and arthritis. If non-surgical treatments fail to alleviate symptoms, reconstructive surgery, known as Arthroplasty, may be a viable option.
Anatomy
The carpometacarpal (CMC) joint is formed by the meeting of the metacarpal bone at the thumb's base and the trapezium bone in the wrist, also known as the basal joint. The ends of these bones are covered with smooth cartilage, allowing them to glide smoothly during movement. Strong ligaments and muscles provide stability and support to the CMC joint.
Causes
Arthritis is the primary cause of CMC joint degeneration, with a higher prevalence in women over 40. Osteoarthritis, in particular, is associated with the wear and tear of the joint over time, causing the smooth cartilage to become rough. As a result, the bones can have difficulty gliding past each other, leading to pain, swelling, and a limited range of motion. In severe cases, the protective cartilage may wear away completely, resulting in bone-on-bone friction during movement, often accompanied by pain and a grinding or popping sensation.
Symptoms
Common symptoms of arthritis at the base of the thumb include pain, stiffness, and swelling. These symptoms often manifest in the morning but may diminish as the thumb warms up. Pain typically intensifies with movement, especially during gripping or pinching activities like opening doors, buttoning clothing, or slicing vegetables. Some individuals may experience pain even at rest. As the CMC joint deteriorates, it can weaken, limiting movement. In some cases, a noticeable bump may form at the outer base of the thumb due to shifting bones.
Diagnosis
A healthcare provider can diagnose arthritis and CMC joint deterioration by assessing symptoms and conducting a physical examination. They will review the patient’s activities, pain patterns, and medical history. An X-ray will typically be ordered to evaluate the condition of the bones, providing a painless image of the thumb area.
Treatment
In the early stages of arthritis at the base of the thumb, non-surgical treatments can provide relief, which may include medications, cortisone injections, and splinting. However, as arthritis is a degenerative disease, symptoms may worsen over time for some individuals. When non-surgical options become ineffective, surgical interventions may be explored, and your physician will help determine the best course of action.
Surgery
Several surgical options exist for treating arthritis in the thumb CMC joint. One common procedure, CMC Arthroplasty, involves reconstructing the joint. This surgery can often be performed on an outpatient basis, though some cases may require an overnight hospital stay. Patients may receive sedation or a local anesthesia that numbs the hand.
There are various methods for joint replacement. One involves stabilizing the metacarpal and using the patient's tendon tissue as a joint spacer. Alternatively, a prosthetic implant may be fitted onto the ends of the bones. The surgeon makes an incision at the base of the thumb to access the joint, removes damaged tissue, and prepares the bone surfaces. If using a stem implant, a small hole is drilled into the bone for placement, and the new joint is reinforced with nearby tendons.
In a different procedure called Spherical Implant Surgery, a small ceramic ball is inserted between the bone ends to create a new joint. The ends of the bones are removed and shaped to securely accommodate the ball, allowing for smooth movement.
Post-surgery, the thumb is padded, and a splint is applied to support healing. Some discomfort and swelling may occur, and your doctor may recommend pain medications. Keeping the hand elevated can also help alleviate symptoms. Physical or occupational therapy is typically advised, with certified hand therapists aiding in regaining motion, strength, and coordination in the CMC joint.
Recovery
Complete recovery from CMC Arthroplasty can take several months. Joint reconstruction usually involves an immobilization period followed by rehabilitation. Recovery typically lasts up to three months for prosthetic implant surgery, whereas Spherical Implant Surgery may allow for a quicker return to activity, often within three to five weeks. Most patients continue to see improvement for several months post-surgery, with many achieving effective use of their thumbs with minimal to no pain.
