Background: Extraspinal manifestations of diffuse idiopathic skeletal hyperostosis (DISH) have been described previously. We aimed to assess the prevalence of elbow hyperostotic spurs, to search for sites discriminating for elbow DISH and to analyze the effect of physical activities, handedness and sex.
Methods: Out of 284 patients hospitalized for extraskeletal disorders, 85 patients (33 with and 52 without thoracospinal DISH) agreed to bilateral elbow X-rays in two projections. Clinical information was collected by a standardized questionnaire and X-rays were graded blindly.
Results: A total of 400 hyperostotic spurs (210 unilateral, 95 bilateral) were present at 11 predefined sites. The most frequent sites affected were the olecranon (20.8%), lateral epicondyle (17.8%) and medial epicondyle (15.5%). In carriers of thoracospinal DISH significantly more hyperostotic spurs were present at the lateral and medial epicondyle compared to non-DISH carriers (OR 4.01 [95% CI 1.35-12.34] and 2.88 [1.03-8.24], respectively). The olecranon, lateral and medial epicondyle contributed significantly to the classification of elbow DISH (OR 22.2 [4.1-144.7], 9.6 [1.9-61.2] and 10.1 [2.2-52.1], respectively). The prevalence of elbow hyperostotic spurs was higher in 45 patients with a history of heavy physical activities (24.4% versus 18.0%, OR 1.48 [1.17-1.86]), at the right elbow (24.2% versus 18.6%, OR 1.39 [1.11-1.75]) and in 62 males (22.8% versus 17.6%, OR 1.38 [1.06-1.81]).
Conclusions: Hyperostotic spurs at the olecranon, lateral and medial epicondyle had the highest prevalence and disclosed the most pronounced discrimination for elbow DISH. Mechanical factors such as physical activities and handedness, and sex influenced the formation of these spurs.