CMC arthroplasty is a surgical procedure for arthritis affecting the base of the thumb. It targets the carpometacarpal (CMC) joint, crucial for the thumb’s range of motion and function. The procedure aims to alleviate pain and restore mobility in individuals with joint degeneration. This surgery is considered when non-surgical treatments no longer effectively manage symptoms.
Understanding CMC Arthroplasty
The carpometacarpal (CMC) joint, often referred to as the basal joint, is located at the base of the thumb, connecting the first metacarpal bone of the thumb to the trapezium bone in the wrist. This unique saddle-shaped joint allows the thumb to move in multiple directions, enabling pinching, grasping, and opposition to other fingers.
A CMC arthroplasty aims to relieve chronic pain and improve the functional capacity of a thumb affected by arthritis. The procedure involves removing the damaged cartilage and often a portion or all of the trapezium bone. The space created by this removal may then be reconstructed, sometimes involving a tendon graft to stabilize the thumb base and maintain proper alignment.
Conditions Treated
The primary condition necessitating a CMC arthroplasty is basal joint arthritis of the thumb, also known as thumb arthritis. This degenerative condition occurs when the articular cartilage at the CMC joint wears away. As the cartilage erodes, the bones rub against each other, leading to inflammation and pain.
Common causes of this arthritis include repetitive stress, previous injuries, and the natural aging process. Individuals experience persistent pain at the base of the thumb, which may worsen with activities like pinching, gripping, or twisting motions. Other symptoms include stiffness, swelling, and decreased strength.
The Surgical Procedure
A CMC arthroplasty is performed using various surgical techniques. The most common is a trapeziectomy, which involves the removal of the trapezium bone. In some cases, this removal is followed by an interposition arthroplasty, where a local tendon fills the void. This tendon acts as a cushion, preventing the thumb metacarpal from grinding against the wrist bones.
Another approach may involve ligament reconstruction, where the tendon graft is used to stabilize the ligaments supporting the thumb base. Implant arthroplasty involves replacing the joint surfaces with an artificial implant. The procedure is typically performed under regional or general anesthesia.
Post-Operative Care and Expected Results
Following a CMC arthroplasty, the thumb is immobilized in a cast or splint for several weeks for healing and protection. This immobilization period typically lasts four to six weeks. Pain management is an important aspect of early recovery, often involving prescribed medications.
Physical or occupational therapy begins after the immobilization period and is a critical component of rehabilitation. Therapy focuses on gradually restoring range of motion, improving strength, and regaining functional use of the thumb and hand. Patients can expect significant pain relief and improved thumb function within several months, with full recovery potentially taking up to a year. Many individuals report performing daily activities with greater ease.
Non-Surgical Options
Before CMC arthroplasty, non-surgical treatments are typically explored to manage thumb arthritis symptoms. These conservative measures include supportive splints or braces to stabilize the joint and reduce painful movements. Over-the-counter or prescription anti-inflammatory medications alleviate pain and reduce swelling.
Corticosteroid injections into the CMC joint provide temporary pain relief by reducing inflammation. Hand therapy teaches patients exercises to improve joint stability and maintain range of motion while modifying activities to reduce stress on the joint. Surgery is considered when non-surgical options no longer provide adequate pain relief or functional limitations impact a person’s quality of life.