What is Thumb Joint Osteoarthritis?
In a normal joint, cartilage covers the ends of the bones and acts as a cushion, allowing for smooth, painless movement. In osteoarthritis (OA) or "degenerative arthritis," the cartilage layer wears down, causing direct contact between the bones, which is initially characterized by pain and eventually leads to deformity. One of the most common joints affected by osteoarthritis in the hand is the first carpometacarpal (1st CMC) joint, also known as the base joint of the thumb. The base joint of the thumb is the joint between the trapezium bone of the wrist and the thumb's metacarpal bone. It is saddle-shaped, which allows for a wide range of motion in the thumb, including upward, downward, along the palm, and pinching.
Who Is Affected by Thumb Joint Osteoarthritis?
Thumb base joint osteoarthritis is more common in women over the age of 40. The exact cause is unknown, but factors such as genetics, previous injuries like fractures or dislocations, and general joint laxity may contribute to the development of this type of osteoarthritis.
What Are the Symptoms of Thumb Joint Osteoarthritis?
The most common complaint is pain at the base of the thumb. Pain may worsen during activities requiring pinching, such as opening jars, turning doorknobs or keys, and writing. Over time, the pain may intensify, leading to pain at rest and even pain that awakens the patient during sleep. In more severe cases, progressive deterioration and deformity of the joint may occur. This misalignment in the joint can cause limited motion and weakness, impairing the thumb's pinching function. The subsequent joint (1st metacarpophalangeal joint) may become loose, causing the thumb to bend further backward to compensate for the decreased range of motion due to osteoarthritis (hyperextension).
How Is Thumb Base Joint Osteoarthritis Diagnosed?
Diagnosis is made based on a detailed history and physical examination. Pain in the joint is felt when pressure is applied externally with a finger and when movements like bending are performed. A grinding sensation may also be present in the joint. X-rays are used to confirm the diagnosis, but the severity of the symptoms is generally not related to the x-ray findings.
How Is Thumb Base Joint Osteoarthritis Treated?
Mild thumb osteoarthritis typically responds to non-surgical treatment. Pain-relieving medications, splinting, and a limited number of ultrasound-guided cortisone injections may help alleviate pain.
Who Should Consider Surgery for Thumb Joint Osteoarthritis?
Surgery should be planned for patients with advanced disease or those who have not responded to non-surgical treatments.
How Is Thumb Joint Osteoarthritis Surgery Performed?
The surgery involves accessing the thumb base joint through an incision. The arthritic trapezium bone is removed. To prevent the thumb base joint from shifting, a tendon on the side of the joint is transferred to the now-empty space. This allows the joint to move without pain, maintaining functions such as writing and grasping objects.
What Is the Recovery Process After Thumb Joint Osteoarthritis Surgery?
Immediately after surgery, a splint (half cast) is applied for one week. After one week, a ready-made splint (easily removable) is used. The goal is to start early movement. Patients typically return to normal function in about eight weeks.
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