Stress-related rib and vertebral changes.

In the course of routine chest examination, 80 asymptomatic patients were observed to have localized hyperostosis of the posterior ribs and articulating transverse processes. The authors studied the distributions of lesions in these 80 patients, and records were reviewed in the 50 cases in which they were available. The occupational histories, male-to-female ratio (5:1), and ratio of right-to-left rib involvement (9:1)--in addition to results of electromyographic and histologic studies and the principles of bone remodeling--suggest that this hyperostosis occurs at sites most stressed with bending and rotation of the thorax. The authors hypothesize that this stress-related change occurs due to the pull of the iliocostalis thoracis muscle and is of no clinical significance.