CARPAL BOSS of the WRIST and HAND

Carpal Boss

  

Clinical Characteristics

The dorsal wrist ganglion is most often confused with the carpal boss, so named by the French physician Foille.  The carpal boss is an osteoarthritic spur that develops at the base of the second and/or third carpometacarpal joints. (figure 1) A firm, bony, nonmobile, tender mass is visible and palpable at the base of the carpometacarpal joints, especially 

when the wrist is volar flexed. The lining of the joint thins out and small bone spurs form n the top of the hand leadingto a bone prominence. Tendon irritation can occur and a small cyst or ganglion may form as well.

figure 1 Right hand with carpal boss

Figure 2 Carpal Boss seen on Xray

Radiologically, the mass is best visualized with the hand in 30 to 40 degrees supination and  

 20 to 30 degrees ulnar deviation ("carpal boss view")( figure 2).

The boss is more common in women (2:1), in the right hand (2:1), and between the third and fourth decades.  The mass may be asymptomatic, but the patient may complain of considerable pain and aching.  A small ganglion is associated with  the carpal boss in 30 percent of cases, adding to its confusion with the more common dorsal wrist ganglion. 

Injection to the ganglion or to the cmc joint may  be used to reduce pain and irritation.  This may be combined with splinting and anti inflammatory medication and avoidance of trauma to the back of the hand\

If symptoms persist at times surgery may be offered. (figure 3) Surgery may involve the removal of the prominent bone, the excision of an associated ganglion or cyst and at times involves tenosynovectomy or tenolysis of adjacent affected tendons.  What occurs during surgery may depend upon the preoperative findings as well as the surgical intra operative findings

Figure 3  Surgical Approach to carpal boss excision using a transverse incision

The most common complication is the persistence of a mass because of excision of the ganglion alone or inadequate excision of the osteophytes.  Pain will persist unless all abnormal abutting surfaces have been excised.  Dorsal wrist ganglions can present over the carpometacarpal joints and must be distinguished from the carpal boss with its own associated ganglion.  Avoidance of injury to branches of the radial and ulnar sensory nerves is again stressed.