A carpal boss is a small bony “lump” that arises on the back of the wrist where the second or third metacarpal bones join the wrist bones. They are most common in young adults 20 – 40 years of age. They occur equally in men and women and can be present in one or both wrists. The lump is often mistaken for a ganglion cyst due to the similarities in appearance and location.
The exact cause of carpal boss is not always clear, but it is believed to result from a combination of genetic factors, repetitive stress, and trauma to the hand. It is thought that certain activities that involve repetitive wrist extension such as weight-lifting, golf or tennis may contribute to the overgrowth of bone due to friction from the wrist extensor tendons attachment to the second or third metacarpal bones may contribute to the overgrowth of bone.
Symptoms of Carpal Boss
A carpal boss, also known as dorsal wrist bossing, will appear as a hard immoveable lump on the back of the hand. They are usually pain-free and therefore require no intervention at all, however some carpal bosses can become painful. A carpal boss which is symptomatic can be tender to press on and can produce pain during movement of the wrist. The tendons which straighten your fingers may also click or snap over the boss, which may cause pain down the index or middle fingers.
Treatment of Carpal Boss
Treatment for a painful carpal boss involves resting in a custom-made wrist extension splint for 4-6 weeks. This prevents any further repetitive movement of the wrist which may be making the carpal boss symptomatic. Our therapists will also use treatment modalities to reduce pain and inflammation in the area. If therapy fails to settle the pain, your doctor may refer you for a steroid injection. In severe cases which do not respond to conservative management, surgery may be required to remove the bony prominence.