The relationship between pelvic floor muscles, lumbar functionality, and urinary incontinence in women with low back pain

Abstract

Introduction: Low back pain of non-specific origin is the most common presentation and is associated with some risk factors such as age and sex, stressors, comorbidities and impairment of the trunk muscles. One of the possible causes of low back pain is the instability of the musculoskeletal structures of the trunk. Lumbopelvic stability is a system that depends on the muscular control of the transversus abdominis (TrA), diaphragm, multifidus and pelvic floor muscles (PFM). The coordinated activation of the PFM and abdominal muscles is important to maintain urinary continence and trunk stability. Objective: To analyze the relationship between pelvic floor muscle strength, lumbar functionality and urinary incontinence in women with low back pain. Methods: Women aged between 40 and 65 years with low back pain were selected in the city of Macaé, Rio de Janeiro, from December 2015 to April 2016. The participants underwent a physical therapy anamnesis and then answered the Oswestry Disability Index (ODI) and Numeric Pain Rating Scale (NPS) questionnaires. Afterwards, the degree of pelvic floor muscle (PFM) strength was identified through bidigital palpation, using the modified Oxford scale and the transverse abdominis muscle activation capacity test (TrA), using the Stabilizer® pressure biofeedback unit. Results: A total of 57 women participated in the study, but three were excluded from the No UI group due to tumors. A total of 54 women were included, 23 without UI (43%) and 31 with UI (57%). The groups were homogeneous in terms of demographic characteristics, pain characteristics, body mass index, lifestyle variables and lumbopelvic function (lumbar disability). Gynecological history (delivery route, climacteric status, use of hormone replacement therapy, sexual activity, history of sexually transmitted disease, menopause, gynecological surgery and contraceptive use) and bowel function did not show statistically significant differences in the chi-square test. There was no statistically significant difference in PFM strength (p= 0.61) and TrA activation capacity (p= 0.4) in women with low back pain with or without UI. There was no significant correlation between PFM and NPS, TrA, ODI, pain duration and age. In women with UI, the Kruskal-Wallis ANOVA test showed no statistically significant difference in pain intensity, lumbar disability, and PFM strength among the three UI groups. However, the mean activation capacity of the transversus abdominis was reduced in the urge UI group when compared to the other groups (urge UI = 2.86 mmHg; effort UI = 8.69 mmHg; mixed UI = 6.6 mmHg; p = 0.016). Conclusion: The results found in this study suggest that the presence of UI in women with low back pain is not directly related to the loss of muscle function in the lumbar spine. Insufficient PFM strength may be a determining factor in the presence of lumbopelvic pain and UI in women.