The factors influencing shoulder mobility disorders in patients after radical breast cancer surgery

Abstract Introduction: To investigate the factors influencing shoulder mobility in terms of pain, grip strength, and supraspinatus muscle thickness in patients with impaired shoulder mobility during radiotherapy after radical breast cancer surgery. Methods: This study included 165 female patients with unilateral breast cancer who had shoulder joint mobility disorders during chemotherapy within 3 months after surgery. The clinical examination included the maximum active range of motion of the shoulder (flexion, extension, abduction, adduction, external rotation, and internal rotation), pain score (visual analog scale [VAS]), grip strength, and supraspinatus muscle thickness. Results: During shoulder abduction, supraspinatus muscle thickness was greatest at 90°, lowest at 0°, and higher at 60° than at 30° (p<0.01). The factors influencing the active movement of shoulder flexion were the VAS score, body weight, grip strength, and supraspinatus contraction rate (R2=0.295), while the factors influencing active shoulder abduction were the VAS score, body weight, grip strength, supraspinatus muscle thickness (drooping position), and supraspinatus contraction rate (R2=0.295). Moreover, the factors influencing the active movement of shoulder external rotation were age, VAS score, body weight, grip strength, and supraspinatus muscle thickness (drooping position) (R2=0.258). There were no intentional results from multiple linear regressions for shoulder extension, adduction, or internal rotation. Conclusion: Pain, weight, grip strength, supraspinatus muscle thickness, and supraspinatus distensibility are the main factors affecting shoulder flexion, abduction, and external rotation. In addition, supraspinatus muscle thickness and contraction rate may be a new index for assessing shoulder dysfunction.