Affiliations: [a] North Georgia College and State University, Department of Physical Therapy, Dahlonega, GA 30597, USA | [b] Department of Physical Therapy, University of Social Welfare and Rehabilitation Sciences, Evin, Tehran, Iran
Correspondence:
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Corresponding author: Mohammad Reza Nourbakhsh, PT, PhD, OCS, North Georgia College and State University, Department of Physical Therapy, 155 Sunset Drive, Dahlonega, GA 30597, USA. Tel.: +1 706 864 1766; Fax: +1 706 864 1493; E-mail: mrnourbakhsh@ngcsu.edu
Abstract: Objective:Specific patterns of muscle impairments, known as Pelvic Cross Syndrome (PCS), in the lumbo-pelvic region have been attributed to causing chronic Low Back Pain (LBP). In PCS, based on their primary functions, muscles are categorized as “postural” or “phasic”, and it has been assumed that phasic (abdominal and gluteal muscle weakness) or postural (decreased flexibility in the hip flexor and back extensor) muscle impairments could lead to an exaggerated Lumbar Lordosis (LL), which in turn might cause chronic low back pain. PCS theory also indicates that exaggerated lordosis in impaired subjects is controlled by hamstring muscle shortening. The purpose of this study was to examine the relationship among Pelvic Cross Syndrome, degree of lumbar lordosis and chronic low back pain. Design:A total of 600 subjects between the ages of 20 and 65 were selected. Subjects were categorized into four groups of males and females with and without low back pain. The degree of LL, the strength of abdominal and gluteal muscles and the extensibility of iliopsoas, erector spine, and hamstring muscles were measured in each group. The cut-off values obtained from Receiver Operating Characteristic (ROC) curve analysis were used to categorize subjects as having weak or short muscles in accordance with the PCS assumptions. The degree of lumbar lordosis in subjects with and without patterns of muscle impairments, and the association between lumbar lordosis and low back pain and the effects of hamstring muscle length on lordosis were assessed. Results:The results of this study showed no significant difference in the degree of LL in subjects with and without patterns of muscle impairment, or in subjects with and without LBP, or in those with and without short hamstring muscles. However, a significant difference in the strength of abdominal and gluteal; and in the length of hip flexor and hamstring muscles was found between subjects with and without LBP. Conclusions:The findings of this study did not support the assumptions of the PCS theory that certain patterns of muscle impairment would lead to exaggerated LL and LBP. Our data indicated that certain muscle impairments could contribute to chronic LBP, but probably not via changing the degree of lumbar lordosis as has been proposed in PCS theory.
Keywords: Low back pain, lumbar lordosis, muscle, flexibility, strength
