This study was carried out to determine the incidence of shoulder injuries in the ipsilateral shoulder of patients who attended our unit with fractures of the humeral diaphysis.

This was a prospective study. 22 patients with fractures of the humeral diaphysis had an early (within 10 days of injury) MRI scan of the shoulder. The contralateral shoulder was also scanned as an internal control. There were 10 male and 12 female patients. The average age was 45 years. 20 were treated non-operatively, and 2 had retrograde intra-medullary nailing of the humerus. 6 patients in our study had a symmetrical MRI scan. The remaining 16 patients had some acute abnormality evident in the ipsilateral shoulder. 11 patients had a significant subacromial bursitis. 2 of these patients had a tear of the supraspinatus tendon. 1 patient had an undisplaced fracture of the coracoid process. The remaining 4 patients had significant AC joint inflammation, 3 being acute, the 4th being acute-on-chronic.

This study shows a high incidence of asymmetrical MRI scans, indicating a definite shoulder injury sustained at the time of the fracture of the humeral diaphysis. We therefore surmise that shoulder pain and dysfunction post antegrade intra-medullary nailing of the humerus may not be due to iatrogenic causes, but may in fact result from concomitant ipsilateral shoulder injury. To our knowledge, this is the first study demonstrating such an association.