When you think about how much you use your thumbs in your day to day lives, it makes sense that an injury to this part of your body can be painful and debilitating. Years of stress to the base of the thumb (CMC) joint can lead to chronic painful osteoarthritis. While an acute injury to this joint can occur as the result of hyper-extension to the CMC joint with extreme force, such as a fall in hockey or falling while skiing holding a ski pole.
The CMC joint (an abbreviation for carpometacarpal joint) of the thumb is where the metacarpal bone of the thumb attaches to the trapezium bone of the wrist. This joint is sometimes referred to as the basal joint of the thumb. The CMC is the joint that allows you to move your thumb into your palm (www.eorthopod.com). This joint is designed to give the thumb its range of motion, but the trade off is that the joint suffers a lot of stress over the years. This can result in joint deterioration and arthritis for some individuals.
The most common symptoms of arthritis are pain, stiffness and swelling. The symptoms may appear upon awakening in the morning and then lessen as the thumb “loosens up”. The pain typically occurs during and after gripping and pinching activities, such as turning a doorknob, buttoning buttons, tying shoes, or using a knife to cut food. As the CMC begins to break down, it may become weaker and movement may be restricted. If the arthritis causes the bones to shift, a bump can appear at the outside base of the thumb.
Several ligaments hold the CMC joint together and provide stability. With a sports injury these ligaments can be injured, ie. when you sprain your thumb. The joint surfaces are covered with a material called articular cartilage. This material is the slick, spongy covering that allows one side of a joint to slide against the other joint surface easily. Damage to the articular joint surface can progress to arthritis.
Your orthopedic doctor can diagnose injury to the CMC joint by evaluating symptoms, completing a physical examination, reviewing your activities and pain patterns, and a history of the problem. X-rays can show the condition of your bones and what is happening at the joint.
If you fracture the CMC joint you will most likely be cast to immobilize the joint and allow the fractured bone to heal. It is important to treat an injury to this joint immediately and thoroughly to help prevent the onset of arthritis.