Do patients with non-traumatic rotator cuff tears differ from healthy individuals in forward head posture, rounded shoulder posture, and thoracic kyphosis?

BACKGROUND: Altered cervicothoracic and scapular posture may influence shoulder mechanics, but it remains unclear whether patients with non-traumatic rotator cuff tears show consistent static postural changes. This study compared the craniovertebral angle, rounded shoulder angle, and thoracic kyphosis angle between patients with non-traumatic rotator cuff tears and healthy individuals. METHODS: This single-center, cross-sectional observational study included 39 patients with imaging-confirmed, full-thickness, non-massive, non-traumatic rotator cuff tears scheduled for repair and 30 healthy controls. Thoracic kyphosis angle was measured using a digital gravity inclinometer, while craniovertebral angle and rounded shoulder angle were assessed using photogrammetry. Unadjusted between-group comparisons were performed using variance-robust tests as appropriate. Multivariable linear regression with HC3 heteroscedasticity-robust standard errors was treated as the principal inferential analysis and adjusted for age, body mass index, sex, and manual labor status. RESULTS: Thoracic kyphosis angle was higher in the case group than in the control group (43.80° vs. 40.23°; mean difference = 3.56°; 95% CI, 0.87-6.26; Cohen's d = 0.59; P = 0.011). No statistically significant unadjusted between-group differences were identified for rounded shoulder angle (50.41° vs. 48.88°; mean difference = 1.53°; 95% CI, -2.58 to 5.64; Cohen's d = 0.19; P = 0.458) or craniovertebral angle (50.78° vs. 47.97°; mean difference = 2.81°; 95% CI, -0.70 to 6.33; Cohen's d = 0.40; P = 0.115). After adjustment, case status remained associated with greater thoracic kyphosis angle (B = 3.98°; 95% CI, 1.30-6.66; P = 0.004), whereas the adjusted associations with craniovertebral angle and rounded shoulder angle were not statistically significant. CONCLUSION: Patients with non-traumatic, full-thickness, non-massive rotator cuff tears had greater thoracic kyphosis than healthy controls. However, the clinical importance of the approximately 3.6° unadjusted difference remains uncertain because protocol-specific measurement error could not be quantified. No statistically significant adjusted associations were identified for craniovertebral angle or rounded shoulder angle; these null findings should be interpreted cautiously given the study's limited sensitivity to moderate or smaller effects.