Are MRI-defined fat infiltrations in the multifidus muscles associated with low back pain?

BACKGROUND: Because training of the lumbar muscles is a commonly recommended intervention in low back pain (LBP), it is important to clarify whether lumbar muscle atrophy is related to LBP. Fat infiltration seems to be a late stage of muscular degeneration, and can be measured in a non-invasive manner using magnetic resonance imaging. The purpose of this study was to investigate if fat infiltration in the lumbar multifidus muscles (LMM) is associated with LBP in adults and adolescents. METHODS: In total, 412 adults (40-year-olds) and 442 adolescents (13-year-olds) from the general Danish population participated in this cross-sectional cohort study. People with LBP were identified through questionnaires. Using MRI, fat infiltration of the LMM was visually graded as none, slight or severe. Odds ratios were calculated for both age groups, taking into account sex, body composition and leisure time physical activity for both groups, and physical workload (in adults only) or daily bicycling (in adolescents only). RESULTS: Fat infiltration was noted in 81% of the adults but only 14% of the adolescents. In the adults, severe fat infiltration was strongly associated with ever having had LBP (OR 9.2; 95% CI 2.0–43.2), and with having LBP in the past year (OR 4.1; 1.5–11.2), but there was no such association in adolescents. None of the investigated moderating factors had an obvious effect on the OR in the adults. CONCLUSION: Fat infiltration in the LMM is strongly associated with LBP in adults only. However, it will be necessary to quantify these measurements objectively and to investigate the direction of this link longitudinally in order to determine if the abnormal muscle is the cause of LBP or vice versa

Physical activity and low-back pain in schoolchildren

Design of the experiment is to study the cross-sectional sample with retrospective information. The objective is to identify the types of physical activity associated with the decreased occurrence of low-back pain (LBP) in schoolchildren. Physical activity may be hypothesized to possess a potential for LBP prevention. The possible connection between LBP and specific sports activities is however sparsely documented. A total of 546, 15- to 16-year-old schoolchildren filled a questionnaire on current physical activities and LBP occurrence and severity. In multiple logistic regressions, the association of LBP with exposure variables was corrected for body height and weight (data from school health service files) and for anthropometric and school furniture parameters. More than half of the children reported pain or discomfort in the low-back region during the preceding 3 months, and 1/4 experienced a decreased functioning or need of care because of LBP. LBP correlated with physical inactivity, e.g. time spent on homework and hours watching TV or video, and with a series of sports activities, e.g. jogging, handball playing and gymnastics. Among sports activities, only swimming and the number of hours per week participating in soccer were associated with a decreased LBP prevalence. With the exception of swimming and soccer, the types of sport reported by this schoolchild population do not offer themselves for consideration as tools for LBP prevention. Based on the associations found with indicators of physical inactivity, attempts to motivate the children to increase their general physical activity level should be considered for trial

In vivo quantification of human lumbar disc degeneration using T1ρ-weighted magnetic resonance imaging

Diagnostic methods and biomarkers of early disc degeneration are needed as emerging treatment technologies develop (e.g., nucleus replacement, total disc arthroplasty, cell therapy, growth factor therapy) to serve as an alternative to lumbar spine fusion in treatment of low back pain. We have recently demonstrated in cadaveric human discs an MR imaging and analysis technique, spin-lock T1ρ-weighted MRI, which may provide a quantitative, objective, and non-invasive assessment of disc degeneration. The goal of the present study was to assess the feasibility of using T1ρ MRI in vivo to detect intervertebral disc degeneration. We evaluated ten asymptomatic 40–60-year-old subjects. Each subject was imaged on a 1.5 T whole-body clinical MR scanner. Mean T1ρ values from a circular region of interest in the center of the nucleus pulposus were calculated from maps generated from a series of T1ρ-weighted images. The degenerative grade of each lumbar disc was assessed from conventional T2-weighted images according to the Pfirmann classification system. The T1ρ relaxation correlated significantly with disc degeneration (r=−0.51, P<0.01) and the values were consistent with our previous cadaveric study, in which we demonstrated correlation between T1ρ and proteoglycan content. The technique allows for spatial measurements on a continuous rather than an integer-based scale, minimizes the potential for observer bias, has a greater dynamic range than T2-weighted imaging, and can be implemented on a 1.5 T clinical scanner without significant hardware modifications. Thus, there is a strong potential to use T1ρ in vivo as a non-invasive biomarker of proteoglycan loss and early disc degeneration