Abdominal Muscle Function in Chronic Low Back Pain Patients

• Published in: Physiotherapy 2002-06, Vol.88 (6), p.322-332
• Main Authors: Critchley, Duncan J, Coutts, Fiona J
• Format: Article
• Language: English
• Subjects: abdominal muscles; Low back pain; transversus abdominis; ultrasound scanning
• ISSN: 0031-9406; 1873-1465
• DOI: 10.1016/S0031-9406(05)60745-6

It has been suggested that transversus abdominis acts as an active stabiliser of the lumbar spine and may be dysfunctional in chronic low back pain patients. Low abdominal hollowing in four-point kneeling is a standard clinical test for transversus abdominis, but is difficult to quantify. Change of muscle thickness may be an indication of transversus abdominis muscle contraction and is measurable with ultrasound scanning. The purpose of this study was to investigate whether there were differences between chronic low back pain and healthy subjects in abdominal muscles' change of thickness during low abdominal hollowing using ultrasound scanning. A pilot study established muscle thickness measurements via scanning as having acceptable short-term repeatability. Twenty chronic low back pain patients and 24 controls were scanned at rest and during low abdominal hollowing in four-point kneeling. The thickness and thickness change of obliquus externus, obliquus internus and transversus abdominis were measured via a standardised procedure. Differences between groups were examined using ANOVA. There was a smaller increase in thickness (mean ± SD) of transversus abdominis in the patients (19.15 ± 24.07%)than controls (49.71 ± 26.76%) (p < 0.001). Resting transversus abdominis thickness was not significantly different. There were no significant differences between groups for the other two muscles in thickness change or in resting thickness, or for age, sex, height, weight, exercise level, abdominal surgery or parity. Real-time ultrasound scanning is potentially a practical means of quantifying transversus abdominis performance. A transversus abdominis dysfunction may occur in many chronic low back pain patients and its assessment and rehabilitation should be considered in these people. The validity of using thickness change as a measure of muscle function, the correlation of transversus abdominis dysfunction with other clinical features and the effect of specific retraining all require further investigation.