Carpal Bossing

An Unusual Cause of a Bump on the Back of the Wrist

Doctor examining a patient's hand. ADAM GAULT/SPL/ GettyImages

Carpal bossing is the name given to a condition that causes a bony lump on the back of the hand. The carpal boss is a bump created by a small area of osteoarthritis occurring at the junction of the long hand bones and the small wrist bones. A carpal boss is most commonly seen as a bump on the back of the hand at the middle or index carpometacarpal joint, where the hand bones meet up with the wrist bones.

The word boss comes from the French word bosse, which means a bump or swelling.

What It Is

Carpal bossing is due to bone growth at the base of the metacarpal bones of the hand. Carpal bossing must be differentiated from other more common wrist conditions such as:

A carpal boss is not a cancer or a tumor.  While there are very rare bone tumors that can occur in the hand, your doctor should be able to differentiate a carpal boss from something more concerning.

Signs of Carpal Bossing

Most patients complain of a carpal boss after they bump or hit against the back of the wrist. This type of trauma can cause irritation around the carpal boss. The tendons over the back of the hand can also become irritated because of the carpal bossing.  Sometimes you may experience tendon snapping as it moves over the bump. Lastly, some patients simply do not like the cosmetic appearance of the bump on their hand.

Your primary care physician may look further into the bump or you may be referred to a hand specialist. If you are having pain and swelling your doctor will want to rule out other causes such as ganglion cyst, tendonitis, fracture and less common causes of bumps on the wrist. A physical exam and listening to your history of when the bump appeared and your symptoms are used to make the diagnosis.

The tests that may be performed include X-rays and EMGs, which are hand electrical neurophysiology tests. 

Treatment of Carpal Bossing

Most often, carpal bossing is a problem that can simply be watched, with no specific treatment. Anti-inflammatory analgesics such as ibuprofen may be suggested if it is painful or inflamed. If it is painful, the doctor may recommend a wrist splint to limit motion or a steroid injection if that doesn't provide relief.

In cases where the condition is causing significant symptoms, a surgical procedure to remove the excess bone can be performed. It is usually done under local or regional anesthetic. It is a brief operation that is performed as a day surgery. An incision is made on the back of hand and the bump and any swollen tissue around it are removed. You can use your hand for normal activity after a few days and return to work in a week or two.

Some surgeons will also fuse the bone at the joint where the spur is located to prevent a recurrence of the condition.

  There are conflicting reports in the literature as to how likely it may be that the bump returns after excision, but it is possible. However, excision has risks of joint instability as well as the common risk of infection and scarring.


"The symptomatic carpal boss. Is simple excision enough?" J Hand Surg, Br. 1999 Oct;24(5):591-5.

Porrino J, Maloney E, Chew FS "Current Concepts of the Carpal Boss: Pathophysiology, Symptoms, Clinical or Imaging Diagnosis, and Management." Curr Probl Diagn Radiol. 2015 Sep-Oct;44(5):462-8. doi: 10.1067/j.cpradiol.2015.02.008. Epub 2015 Mar 7.

Park MJ, Namdari S, Weiss AP. "The carpal boss: review of diagnosis and treatment." J Hand Surg Am. 2008 Mar;33(3):446-9. doi: 10.1016/j.jhsa.2007.11.029.

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