The Factors Influencing Shoulder Mobility Disorders in Patients after Radical Breast Cancer Surgery: A Cross-Sectional Study.

INTRODUCTION: This study is a cross-sectional study that investigated the factors influencing shoulder mobility in terms of pain, grip strength, and supraspinatus muscle thickness in patients with impaired shoulder mobility during chemotherapy 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 ( R 2 = 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 ( R 2 = 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) ( R 2 = 0.258). There were no significant 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.