Carpometacarpal (CMC) Arthritis of the Thumb:
Carpometacarpal (CMC) arthritis, also known as thumb arthritis, is a common condition that affects the joint at the base of the thumb, where the thumb meets the wrist. It can lead to pain, stiffness, and weakness, often making it difficult to perform everyday activities such as opening jars or typing.
Description:
CMC arthritis refers to osteoarthritis (OA) that occurs at the base of the thumb, where the first metacarpal bone meets the trapezium bone in the wrist. This joint is known as the CMC joint, and when it becomes arthritic, it leads to pain, inflammation, and progressive loss of function. It is one of the most common forms of arthritis in the hand and typically develops as a result of aging, overuse, or previous trauma to the thumb.
Because the thumb is essential for gripping, pinching, and other fine motor tasks, CMC arthritis can significantly impact daily activities. It is more common in women, especially post-menopausal women, due to hormonal changes that affect joint health.
Anatomy, Physiology, and Function:
The CMC joint is located at the base of the thumb, where the first metacarpal (the bone in the palm) meets the trapezium (one of the wrist bones in the distal row of carpal bones). This joint is a saddle joint, which means it allows movement in two planes: forward and backward (flexion and extension), and side-to-side (abduction and adduction). This unique structure allows for the wide range of thumb motion necessary for tasks like grasping, pinching, and holding objects.
- Cartilage: In a healthy joint, cartilage covers the bones and allows smooth, pain-free movement. Cartilage also acts as a cushion, absorbing shock and preventing the bones from rubbing together.
- Ligaments and Tendons: Ligaments around the CMC joint provide stability and support, while tendons control movement, allowing the thumb to function properly.
In osteoarthritis, the cartilage at the CMC joint wears down over time, which can lead to bone-on-bone contact. This causes inflammation, pain, and swelling, ultimately reducing the thumb’s ability to move smoothly and efficiently.
Mechanism of Injury:
The main mechanism behind CMC arthritis is the gradual breakdown of cartilage due to wear and tear over time. There are several factors that can contribute to the development of this condition:
- Aging: As we age, the cartilage in joints naturally breaks down, which is a key factor in the development of osteoarthritis.
- Overuse: Repeated motions or activities that involve heavy gripping, pinching, or forceful use of the thumb can lead to increased wear on the CMC joint. This is common in people who perform manual tasks regularly, such as carpenters, musicians, or people who use tools or smartphones extensively.
- Previous trauma: A history of trauma to the thumb, such as a sprain, fracture, or dislocation, can lead to early degenerative changes in the CMC joint, increasing the risk of developing arthritis.
- Genetics: Some individuals may have a genetic predisposition to develop osteoarthritis in the thumb joint, particularly if there is a family history of arthritis.
- Hormonal changes: Women, especially post-menopausal women, are at a higher risk due to the hormonal changes that affect cartilage and joint health.
Risk Factors:
There are several factors that increase the likelihood of developing CMC arthritis of the thumb:
- Age: The risk of developing CMC arthritis increases with age, especially after 40-50 years.
- Gender: Women, particularly those who are post-menopausal, are more likely to develop CMC arthritis due to hormonal changes that affect cartilage and joint health.
- Family history: A family history of osteoarthritis or other forms of joint disease may increase the risk of developing arthritis in the thumb.
- Occupation or repetitive hand use: People who perform repetitive tasks involving gripping or pinching, such as manual laborers, musicians, or those who spend long hours on computers or smartphones, are at higher risk.
- Previous thumb injuries: A history of trauma, such as fractures or dislocations in the thumb, increases the risk of developing arthritis in the CMC joint.
Signs and Symptoms:
The symptoms of CMC arthritis typically develop gradually and can range from mild discomfort to severe pain and disability. Common signs and symptoms include:
- Pain: Pain at the base of the thumb, especially when gripping, pinching, or performing tasks that require fine motor control.
- Stiffness: Difficulty moving the thumb, particularly when trying to bend or straighten it. This is often worse in the morning or after periods of inactivity.
- Swelling: Swelling and inflammation around the CMC joint, particularly after activity.
- Weakness: Decreased strength in the thumb, which can make tasks like opening jars, typing, or holding objects difficult.
- Grating or Crunching Sensation (Crepitus): A feeling of grinding or popping when moving the thumb, caused by the bones rubbing against each other due to the loss of cartilage.
- Deformity: In more advanced cases, the thumb joint may become visibly deformed, with a noticeable bump or “squaring” of the thumb at the base.
The severity of these symptoms can vary, with some individuals experiencing only mild discomfort, while others may struggle to perform daily tasks due to pain and weakness.
Physiotherapy Management:
Physiotherapy plays an essential role in managing CMC arthritis and can help to alleviate pain, restore function, and improve the quality of life. Treatment strategies include:
- Education: Educating patients about joint protection strategies, such as using adaptive devices, modifying tasks to avoid excessive stress on the thumb, and avoiding prolonged gripping or pinching.
- Manual therapy: Techniques such as joint mobilisations and soft tissue therapy may be used to reduce pain, increase range of motion, and improve the overall function of the thumb joint.
- Strengthening exercises: Strengthening the muscles around the thumb and wrist can help stabilize the CMC joint and reduce the load on the affected area. Specific exercises can improve grip strength and function.
- Range of motion exercises: Stretching and mobility exercises can help maintain or improve thumb flexibility, reducing stiffness and improving movement.
- Splints and braces: A thumb splint or brace can provide support, reduce pain, and limit motion during the acute phases of arthritis. This can help reduce the risk of further cartilage wear and provide relief during activities that exacerbate symptoms.
- Heat or cold therapy: Applying heat or cold to the joint can help alleviate pain and reduce inflammation. Heat may also help relax stiff muscles around the thumb.
A physiotherapist will develop an individualised treatment plan based on the severity of the arthritis and the specific needs of the patient.
Surgical Management:
In more advanced cases of CMC arthritis, when conservative treatments no longer provide sufficient relief, surgical intervention may be considered. Some surgical options include:
- Arthroscopy: A minimally invasive surgery in which small incisions are made to insert a camera and small instruments to clean out damaged tissue or remove bone spurs. This can provide pain relief and improve joint function.
- Joint Fusion (Arthrodesis): In cases of severe arthritis, the thumb’s CMC joint may be surgically fused to eliminate painful motion. While this can reduce pain, it also eliminates the ability to move the thumb at the base, which can affect function.
- Joint Replacement: In some cases, a prosthetic joint replacement may be considered to replace the damaged CMC joint. This can restore function and relieve pain, although it is less common than joint fusion.
After surgery, rehabilitation through physiotherapy is essential to restore strength, mobility, and function of the thumb.
Conclusion:
CMC arthritis of the thumb can be a challenging condition, but with appropriate management, many people can continue to lead active, pain-free lives. Physiotherapy plays a vital role in reducing pain, improving strength, and maintaining function of the thumb. If you are experiencing symptoms of CMC arthritis, seeking early intervention can help prevent further damage and improve your quality of life.
If you have questions or would like to discuss how physiotherapy can help you manage thumb arthritis, feel free to contact us for more information.
References:
- Aebischer, B., Elsig, S. and Taeymans, J. (2015) ‘Effectiveness of physical and occupational therapy on pain, function and quality of life in patients with TRAPEZIOMETACARPAL osteoarthritis – A systematic review and meta-analysis’, Hand Therapy, 21(1), pp. 5–15. doi:10.1177/1758998315614037.
- Colditz, J.C. (2013) ‘An exercise program for carpometacarpal osteoarthritis based on biomechanical principles’, Journal of Hand Therapy, 26(1), pp. 81–82. doi:10.1016/j.jht.2012.10.002.
- Esteban Lopez, L.M.J. et al. (2023) ‘Long-term outcomes of nonsurgical treatment of thumb carpometacarpal osteoarthritis’, Journal of Bone and Joint Surgery, 105(23), pp. 1837–1845. doi:10.2106/jbjs.22.01116.
- Gillis, J., Calder, K. and Williams, J. (2011) ‘Review of thumb carpometacarpal arthritis classification, treatment and outcomes’, Canadian Journal of Plastic Surgery, 19(4), pp. 134–138. doi:10.1177/229255031101900409.
- Villafañe, J.H. et al. (2019) ‘Thumb carpometacarpal osteoarthritis: A musculoskeletal physiotherapy perspective’, Journal of Bodywork and Movement Therapies, 23(4), pp. 908–912. doi:10.1016/j.jbmt.2019.02.018.
