Thumb pain or numbness? It could be osteoarthritis.

Thumbs are integral to how we use our hands. They help us open jars, grab bags and hold pencils. As we age, the joint in our thumb can deteriorate from wear and tear, just like other joints in the body. The condition is called carpometacarpal (CMC) osteoarthritis. It leads to numbness and pain near the thumb, and it’s more common among women than men.

Joint Instability at the Base of the Thumb

The base of the thumb may not be where you think it is. It’s where the meaty part of your palm below the thumb meets the wrist. This is the carpometacarpal joint.

“Carpometacarpal osteoarthritis can also be referred to as basilar thumb arthritis, as in the base of the thumb,” explains Matthew Grothaus, MD, MSOH, FAAOS, with ProMedica Physicians Defiance Orthopaedic Center. “If you get some instability in these joints, then you start to have not so much a compressive, or pressing, force across the joint, but a shearing, or sliding, type of force.”

The shearing force from joint instability acts like sandpaper, wearing away the cartilage at the joint of the thumb. In the early stages of CMC arthritis, individuals can develop bone spurs, plus widening or narrowing of the joint. This can lead to numbness, pain between the thumb and the wrist, loss of grip strength and difficulty using the hand.

“Progressively what happens is you go through these four stages of CMC arthritis, and it just gets worse. At stage four, there’s basically no remaining cartilage. Accompanied with the instability of the joint ligament, it can actually cause that thumb joint to come out of the socket,” explains Dr. Grothaus.

CMC Arthritis Tends To Affect More Women Than Men

CMC arthritis can affect both men and women, but it seems to be more common in women. Why? The medical community isn’t completely sure.

“We don’t truly have an answer yet as to why it happens more in women. It’s been postulated that it’s because of hormonal factors – maybe the estrogen/progesterone factor. But then there’s been some other studies that have completely refuted that,” explains Dr. Grothaus. “It may very well be the way that women tend to use their hands, which is in a different manner than men.”

While osteoarthritis in general does have some hereditary influence, CMC arthritis is more of a “wear and tear” type of arthritis. That means you’re more likely to develop it from how you use your thumb than due to genetic factors. It’s a multifactorial condition, meaning it’s caused by many things. Age may also play a role as the condition tends to affect individuals in their 50s and 60s.

Treatment for CMC Arthritis

Conservative treatments should be used first when it comes to managing CMC arthritis. Nonsteroidal anti-inflammatory medications (NSAIDs) and a brace to stabilize the thumb may help reduce inflammation and pain. Cortisone, or corticosteroid, injections can also be helpful for pain relief because they reduce swelling and inflammation.

“If CMC arthritis is causing you to not do the things you enjoy, it’s affecting your daily life and decreasing your quality of life, and conservative treatments have failed, surgery may be an option,” says Dr. Grothaus. “At that point, you have a smorgasbord of procedures that can be done.”

Being fellowship-trained in hand and upper extremities from the Indiana Hand Center, Dr. Grothaus has seen a variety of procedures used for CMC arthritis. One is the initial procedure used back in the early 1900s. “The mainstay of that procedure is taking the little bone out of the base of the thumb,” he describes.

Other procedures add biological tissue to suspend the bone or act as a cushion. Implants can also be used, similar to knee and hip procedures.

Before deciding on surgery, patients should talk with their orthopaedic surgeon about their options, quality of life and commitment to treatment. Patients should know what to expect with surgery and recovery and make sure that they are fully committed to the journey.

As with any surgery, Dr. Grothaus explains that with CMC surgery, “the most important part of the process is your mindset going into it.”

Matthew Grothaus, MD
Dr. Grothaus is an orthopaedic surgeon with ProMedica Physicians. View his profile.