MRI diagnosis of carpal boss and comparison with radiography.

Background A carpal boss is a potentially painful bony mass in the region of the second or third carpometacarpal joint. The combination of clinical examination and radiography is usually sufficient for the diagnosis. Purpose To determine whether magnetic resonance imaging (MRI) examination of the quadrangular joint can assist the diagnosis of persistent pain near a carpal boss. Material and Methods Fifty-seven patients with a carpal boss were retrospectively reviewed using MRI and conventional radiographs and compared to an asymptomatic control group. Results MRI demonstrated a variable morphology and a variety of bone and soft tissue abnormalities associated with carpal boss. Bone marrow edema around the quadrangular joint shows a significant correlation (Fisher's exact test: P < 0.001) and a positive correlation (Pearson's test r = 0.632, significant at the 0.01 level [two-tailed]) with a painful carpal boss. Conclusion MRI offers detailed examination of bone and soft tissue abnormalities associated with a carpal boss. Local bone marrow edema strongly correlates with a painful carpal boss.