What is basal joint arthritis?
Basal joint arthritis is a common condition. In our modern life we don’t typically use our hands in such extremely rigorous physical work like working in fields or factories, but with our extended life spans and repetitious tasks like typing and exercise regimens, our bodies can fail, or at the very least show signs of wear.
The basal joint or CMC (carpometacarpal) refers to the base of the thumb and is particularly susceptible to wear. It the second most mobile joint in the body– first is the shoulder- and what the saddle joint gains mobility it sacrifices in stability. This joint is made up of the longer metacarpal and the trapezium (one of the carpal bones nearer the wrist). Using the hand compresses and loads the joint as the thumb opposes the fingers for grasp and pinch. Hyaline cartilage is the tough covering of the ends of bone that come together to comprise a joint. A capsule encloses the joint, and provides a chamber for the synovial fluid to lubricate and bathe the avascular cartilage in nutrients and gaseous metabolites. When hyaline cartilage is healthy and intact, it’s slippery and provides a nearly friction-free glide as the bones make contact during motion. When the cartilage is damaged, friction erodes the surface and can wear through the cartilaginous cover until it ultimately reaches the bone. Bone tissue is highly innervated, unshielded, and is unable to tolerate the loading and shearing forces involved in loading a joint during normal functional activities. Bone rubbing is painful resulting in inflammation and joint collapse. At the base of the thumb, the joint loses stability and falls into the palm. Muscles along the thumb metacarpal exert a strong pull exacerbating the deformity.
Who is primarily affected?
CMC Osteoarthritis is a common condition affecting people over 50, more women than men; it affects 25% of women over 55, and more than 70 percent of the population over 75 years of age. If the cause was from trauma, symptoms may appear earlier. Many people have come to me and wished they knew more about ways to save their joints sooner or learn about protecting their joints without intervention.
What are some of the causes of basal joint arthritis?
Arthritis = joint (arthro-) + inflammation (-itis). Arthritis is a general term and doesn’t tell us about the cause of the symptoms. As mentioned above, osteoarthritis occurs because of damage to the cartilage. Osteoarthritis can occur naturally without any particular cause, such as joint laxity, or it can occur secondarily as a result of trauma, infection, anatomical abnormalities or metabolic changes (like menopause). These conditions may contribute to the wearing down of the cartilage. As we age, the ability of the cartilage to replace cells that are damaged diminishes. Note that thumb and thumb-sided wrist pain can be caused for reasons other than thumb osteoarthritis, and so you may wish to seek medical advice yourself to rule out other diagnoses which may not be helped with treatment for this diagnosis.
What treatments are available for CMC arthritis?
Treating arthritis is a matter of sparing the base of the thumb from erosive forces. There are non-surgical and surgical options. Non-surgical options are tried first, and if these options fail, then surgery may be indicated.
With non-surgical methods, joint protection is stressed. It is important to protect the joint actively as well as passively. Passive protection is wearing a splint that limits motion and therefore limits stress across the joint while adding stability. Splints can be non-rigid or rigid and are worn during activities and/or while sleeping. Arthritis medication and limited cortisone injections may reduce pain.
Joint protection is important to preserve the joint surfaces and limit further damage. There currently is no “fix” to replace worn or damaged cartilage. I encourage my patients to adapt their tasks and avoid using their thumbs by changing hand position, using a tool or device that allows them to perform the task without having to grip or pinch with a lot of effort. A certified hand therapist can provide solutions for tasks that are unique to you!
There are a variety of surgical options designed to reduce or eliminate pain. The most common surgical intervention is removing the small bone at the base of the metacarpal joint and the reconstructing it.
But most people go the surgical route because the pain becomes enough that other options can’t relieve it. As many have said their bodies told them when to do it!
Avoid worsening symptoms by talking with a hand surgeon or rheumatologist. If your symptoms are mild you may start with a rheumatologist. This physician can follow the course of the disease over time and treat it frequently with medications and with hand therapy. You may seek a hand surgeon when you feel occasional or even frequent distracting or debilitating pain. Both can diagnose you and write prescriptions for medications or hand therapy. A reputable surgeon would do a procedure only after exhausting conservative treatment methods.
What research and resources are available for basal joint arthritis?
The Hospital for Special Surgery performs a range of studies on topics related to arthritis, including effective splinting and managing CMC OA by injecting a lubricant to preserve the joint and decrease pain.
In addition, there are arthritis support and information groups that meet here at HSS on a regular basis. You can find a list of current programs on our website: https://hss.edu/classes-programs.asp.
