Dynamic body posture after unilateral mastectomy: a pilot study

Background: Postural changes after unilateral mastectomy may appear in relation to the dominant hand, postoperative duration, and dynamic conditions. This study aimed to compare the postural changes by inclination angles and muscle activities in the static and dynamic sitting position between women with breast cancer who underwent mastectomy and women who did not have breast cancer.

Methods: The observational study design was conducted. We evaluated 17 women who underwent modified radical mastectomy (MRM) more than 1 year prior to the study. They were categorized into the Rt. mastectomy group (n=7) and the Lt. mastectomy group (n=10). An aged-matched cohort of 8 healthy females was also included. The inclination angle in both static and dynamic sitting positions was measured using the balance board system (BBS), and the muscle activities of 8 muscles were measured in the dynamic sitting position.

Results: There was no significant difference in demographic characteristics between the patients, and all patients were right-handed. The inclination angle of the anterior-posterior axis when leaning forward was significantly increased to the anterior side in the Rt. mastectomy group than in the Lt. mastectomy group. Meanwhile, the inclination angle in the static sitting position and when tilted backward to both directions did not differ among the 3 groups. The inclination angle of the right-left axis was statistically increased to the left side during tilting anterior-left direction in the Rt. Mastectomy group. The muscle activities of the thoracic erector spinae were significantly lower when tilted backward in the Rt. mastectomy group than in the Lt. mastectomy group.

Conclusions: Compared with left mastectomy, right unilateral mastectomy yielded more postural changes under dynamic sitting state in right-handed female patients with breast cancer. Thus, to maintain the trunk balance and prevent the postural changes after unilateral mastectomy, the postoperative exercise programs for the para-thoracic muscles will be helpful.