Differences in cervical mobility and pain sensitivity between patients with rotator cuff-related shoulder pain and asymptomatic subjects: a cross-sectional study.

Introduction: The cervical spine's role in shoulder pain remains unclear, particularly regarding its influence on shoulder pain severity and functional limitations. This study aimed to compare neck mobility, pain sensitivity, and strength between patients with rotator cuff-related shoulder pain (RCRSP) and asymptomatic controls and to explore associations between neck active range of motion (AROM) and shoulder outcomes. Methods: A cross-sectional study was conducted with 50 patients with RCRSP and 50 asymptomatic controls. Neck AROM was measured with a CROM device, pressure pain thresholds (PPTs) with a digital algometer, and isometric neck strength with a handheld dynamometer. Shoulder pain and disability were assessed using the Visual Analog Scale (VAS) and the Shoulder Pain and Disability Index (SPADI). Results: Compared to controls, patients with RCRSP exhibited reduced neck rotation toward the affected shoulder (mean difference: -5.19°; 95% CI: -8.84 to -1.38) and lower PPTs bilaterally (affected side: -1.49 kg/cm²; 95% CI: -1.99 to -1.00; unaffected side: -1.42 kg/cm²; 95% CI: -1.98 to -0.91). No differences were found in neck strength. Regression analysis showed that greater neck flexion, lateral flexion toward the affected side, and reduced protraction were associated with higher SPADI scores. Additionally, neck lateral flexion and rotation toward the affected side were negatively associated with shoulder pain intensity over the last week. Conclusion: These findings suggest a potential interaction between the cervical spine and shoulder in RCRSP, underscoring the importance of a comprehensive assessment of both cervical and shoulder impairments in this condition.