Abstract
BACKGROUND: Traumatic postero-superior Rotator Cuff Tears (RCT) and isolated Greater Tuberosity fractures (GTF) are equivalent injuries resulting in significant shoulder dysfunction if left retracted or displaced. The difference in morphometric aetiology is unclear. A raised critical shoulder angle (CSA) has been associated with rotator cuff degeneration. We hypothesised that traumatic RCT is associated with a raised CSA when compared to GTF. METHODS: A retrospective study was conducted across the two trauma units in our institution. All patients between the period of 2010 and 2020 with Traumatic GTF or RCT assessed on cross-sectional imaging (CT or MRI) were identified. Patients were case-matched by age, gender, mechanism and laterality of injury. The primary outcome measurement was the Critical Shoulder Angle (CSA). Other radiographic features of subacromial degenerative change, mechanism of injury, association with shoulder dislocation and delay to diagnosis were also compared. RESULTS: Eighty patients met the inclusion criteria(40 traumatic RCT and 40 GTF). The mean age was 61.8 years with 58(72.5%) left-sided injuries. Thirty-four (43%) were female.The mean CSA was 3.96° higher in the RCT group (95% CI 2.5 to 5.41, p < 0.05). A CSA of 33.73 gave a sensitivity of 0.68 and a specificity of 0.8 to differentiate between RCT and GTF. Patients with RCT were far more likely to display subacromial degenerate changes and experience a significant delay in diagnosis, whereas those with GTF were more likely to have suffered a shoulder dislocation. CONCLUSIONS: Patients with traumatic RCT have radiographic features and scapular morphology associated with degenerative rotator cuff disease compared to those with GTF. This supports the theory that tears occur on the background of pre-existing tendon degeneration. Careful assessment of these parameters, combined with clinical assessment, may help guide the provision of appropriate diagnostic imaging. LEVEL OF EVIDENCE: III.