Anatomic extension-based description for rotator cuff calcifications: retrospective analysis of 100 consecutive cases

Background: Rotator cuff calcific tendinopathy (RCCT) has traditionally been described as a localized enthesopathy. However, calcium deposits sometimes extend beyond the enthesis into adjacent soft tissues or humeral bone, resulting in atypical patterns not considered in existing classification systems. Failure to recognize these patterns can lead to diagnostic errors or the indication of unnecessary invasive diagnostic procedures. Methods: In order to describe atypical patterns and to assess their incidence, 100 consecutive shoulder cases with radiographically confirmed RCCT were retrospectively reviewed. Calcific deposits were categorized by tendon involvement, size, and morphology. Based on imaging findings, deposits were also classified according to their anatomic location and extension into: Type I (enthesis-confined), Type II (extension into soft tissue), and Type III (bone involvement). Associations between patient characteristics, calcification size, morphology, and location were analyzed. Results: According to the proposed classification, 67% of cases were Type I, 14% showed soft tissue extension (Type II), and 19% involved bone (Type III). Type III group showed a significantly higher proportion of females (83%) compared to the entire cohort (54%) (p < 0.001). Larger deposits (>15 mm) were significantly associated with bone involvement (p < 0.01). Conclusion: Extension of calcium deposits beyond the rotator cuff enthesis was a frequent finding in this series. Incorporating an anatomic extension-based classification may enhance diagnostic precision, possibly avoiding invasive differential diagnostic procedures. Level of Evidence: IV.