Excavated type of rhomboid fossa of the clavicle: a radiological study

The excavated type of rhomboid fossa of the clavicle is a relatively neglected anatomical structure that can potentially cause diagnostic problems. Its unilateral occurrence may be confused by the physician as avascular necrosis, osteomyelitis, or even a tumour. We studied 80 routine chest radiographs and identified the clavicles with excavated type of rhomboid fossa. The sex, sidedness, and handedness were recorded. An excavated type of rhomboid fossa was present in 43 clavicles (26.88%), appearing more frequently in males than in females. In addition, the incidence of the excavated type of rhomboid fossa was greater on the right side than on the left. That type of fossa was also present more frequently on the right side in right-handed specimens and on the left side in left-handed specimens. The high incidence of the excavated type of rhomboid fossa on the dominant hand supports the mechanical theory of fossa formation. Radiologists and physicians should be aware of this fossa, as it may resemble a pathological condition. (Folia Morphol 2009; 68, 3: 163–166)