Impact of waist/hip ratio on the therapeutic efficacy of lumbosacral corsets for chronic muscular low back pain.

Aseries of 143 new outpatients who had had chronic low back pain for longer than 3 months, with neither a positive straight leg raise test nor radiographic abnormality including lumbar spondylosis, were treated for 4 weeks with a traditional lumbosacral corset or one with a front-to-back tensile band (extensile corset). Randomization was performed according to birth date. Radiographs were used to analyze the change in sacral inclination angle with and without the respective corset. Central obesity subgroups consisted of men with a waist/hip ratio (W/H) of > or =90% and women with a W/H ratio of > or = 80%. Quebec Back Pain Disability Scale scores were measured at baseline and at 4 weeks. The mean changes in sacral inclination were +3.8 degrees +/- 5.4 degrees in the extensile corset group ( n = 72) and -2.6 degrees +/- 4.6 degrees in the traditional corset group ( n = 71). Thus, the extensile corset had a mechanical effect opposite to that of the traditional corset. Participants without central obesity who were treated with the extensile corset ( n = 30) demonstrated significant improvement compared to participants with the traditional corset ( n = 33) ( P = 0.034). Central obesity should be considered when recommending corsets for patients with chronic muscular low back pain.