Magnetic resonance imaging of lumbar trunk parameters in chronic low backache patients and healthy population: a comparative study.

Abstract

The aim of this study was to evaluate the lumbar trunk parameters by MRI and investigate their association with chronic low backache. Fifty patients (26 males and 24 females) with mean age 33.54±8.33years with a history of low back pain (LBP) of minimum 3 consecutive months constituted the study group (Group A). To match with the study group, 15 normal healthy volunteers (9 males and 6 females) with no history of back pain were selected (Group B). Both the groups were subjected to magnetic resonance imaging of lumbosacral spine and lumbar trunk parameters were calculated. Trunk width, depth and skin angle were comparable at L3-L4, L4-L5 and L5-S1 disc levels; significant difference with regard to disc angle of L3-L4 (p=0.005) and L4-L5 (p=0.02) and cross-sectional area (CSA) of disc at L4-L5 level (p=0.01) was observed between two groups. There was a tendency of smaller CSA of paraspinal and abdominal oblique muscles in Group A patients, but the measurements were not statistically different from Group B patients. Rectus abdominis muscles showed a unique pattern of larger CSA at L3-L4 and L4-L5 disc levels and smaller CSA at L5-S1 in LBP patients. Intervertebral disc degenerative changes on MRI were observed in 27 (54%) patients in the Group A; and none of the Group B participants showed degenerative changes. Tendency of smaller trunk musculature CSA may be a cause or a result of chronic LBP. A unique pattern of larger CSA at L3-L4 and L4-L5 disc levels and smaller CSA at L5-S1 of Rectus abdominis muscles is observed in LBP patients compared to healthy persons. Differences in disc angles and CSA of disc at L3-L4 and L4-L5 levels between the two groups signify that these may be the predisposing factors leading to LBP due to abnormal load/stress transmission and precipitating early degenerative changes in the disc.