How to discriminate between acute traumatic and chronic degenerative rotator cuff lesions: an analysis of specific criteria on radiography and magnetic resonance imaging

Background Discrimination between acute traumatic and chronic degenerative rotator cuff lesions (RCLs) is an important aid to decision making in therapeutic management. To date, no clinical signs or radiologic findings that enable confident differentiation between these distinct etiologic entities have been identified. The purpose of this investigation was to perform a systematic analysis of known radiographic and magnetic resonance imaging (MRI) features of RCLs and of further, not yet accurately described parameters. The hypothesis was that there are specific radiologic features that allow reliable discrimination between traumatic and nontraumatic RCLs. Methods Fifty consecutive patients with RCLs confirmed by MRI were enrolled in this study. Group A was made up of 25 patients with a history of trauma within the previous 6 weeks and no pre-existing shoulder pain, whereas group B comprised 25 patients with shoulder pain for not more than 12 months and no history of relevant trauma. Radiographs and magnetic resonance images were analyzed in a standardized protocol. Results No radiographic features were found to differ significantly between the 2 groups. On MRI, edema in the injured muscle was more common in group A (37.5% vs 4%, P = .04). A characteristic feature in traumatic RCLs was a wavelike appearance (kinking) of the central tendon (64% vs 32%, P = .03). In group B, more muscular atrophy was found (29.2% vs 60%, P = .02). Thinning and retraction did not differ between the groups. Conclusion MRI, but not radiography, can be used to help discriminate between traumatic and nontraumatic RCLs. Although no absolute distinguishing feature was found, edema, kinking, and muscular atrophy are positive criteria for differentiation.