Thumb and hand pain can result from a variety of diseases, injuries, and other conditions, but a few are particularly common. In the thumb, osteoarthritis can cause pain at the carpometacarpal (CMC) joint, found at the very base of the thumb alongside the wrist. Less commonly, rheumatoid arthritis, which differs from osteoarthritis in that it involves inflammation of the synovial membrane within the joint rather than a wearing of the joint cartilage, can afflict the hands and thumb, often at the interphalangeal joints, or knuckles. If the pain in the hand is generalized and accompanied by tingling and numbness, it may be caused by carpal tunnel syndrome, another common cause of thumb and hand pain.
Affecting the joints of millions of people worldwide, osteoarthritis is characterized by inflammatory pain at a joint and is a common cause of thumb and hand pain. The result of a gradual wearing on joint structures, namely the cartilaginous disks providing cushioning between the adjacent bones of the joint, osteoarthritis can be caused by age, injury, obesity, or certain diseases. Symptoms include pain, tenderness, and swelling at the joint, as well as joint stiffness and difficulty in movement. The articulation in the hand most typically affected by osteoarthritis — also known as degenerative joint disease — is the carpometacarpal joint. Pain at this joint is felt during a wide range of movements, from gripping a pen to opening a jar or turning a doorknob.
Another type of arthritis that can result in thumb and hand pain is rheumatoid arthritis. Rheumatoid arthritis affects the synovial joints of the hand — those that can produce movement — and is caused by an overproduction of cells in the synovial membrane lining the joint. This overproduction, also known as hyperplasia, generates an inflammatory response at the joint characterized by inflammation of the membrane and build up of synovial fluid within the joint membrane.
Symptoms of rheumatoid arthritis are commonly felt in the smaller knuckles of the fingers and larger knuckles of the hand. They are more disabling than those of osteoarthritis and include pain, swelling, tenderness, and warmth at the joint. Other symptoms include stiffness and limited range of motion, particularly first thing in the morning. Rheumatoid arthritis can eventually lead to deformity.
A more general feeling of thumb and hand pain can result from carpal tunnel syndrome. This injury is classified as a repetitive strain injury (RSI). Carpal tunnel occurs when the median nerve passing between the carpal bones of the wrist as it enters the hand is pinched by swollen and inflamed tendons entering the hand alongside it.
These tendons belong to the wrist extensor muscles in the forearm. Inflammation occurs when these muscles are frequently overused, as in bending back one’s wrists to type on a computer. Carpal tunnel syndrome is felt as numbness, tingling, and pain spreading through the hand to the four fingers. This pain can also radiate up the arm and can become worse upon performing the activity that caused it.