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Spine

INTRINSIC SHAPE OF THE LUMBAR SPINE AND ITS EFFECT ON LIFTING MANOEUVRES

The Society for Back Pain Research (SBPR) Annual General Meeting: ‘Spotlight on sciatica’



Abstract

Background and Aim

Low back pain is highly prevalent, particularly in manual occupations. We previously showed that the lumbar spine has an intrinsic shape, identifiable in lying, sitting and standing postures, that affects the spine's response to load. Its effects on motion are unknown. Here we investigate whether intrinsic spinal shape is detectable throughout a greater range of postures and its effect on how healthy adults lift a weighted box.

Methods

The lumbar spine was imaged using a positional MRI with participants (n=30) in 6 postures ranging from extension to full flexion. Active shape modelling was used to identify and quantify ‘modes’ of variation in lumbar spine shape. 3D motion capture analysed participants' motion while lifting a box (6–15 kg, self-selected).

Results

Two modes accounted for 89.5% of variation in spinal shape, describing the overall curvature (mode 1) and distribution of curvature (mode 2). Within the first 9 modes, scores were significantly correlated between all six postures (r = 0.4−0.97, P<0.05), showing that intrinsic shape was partially maintained throughout. Individuals with straighter spines lifted with greater knee flexion (r = 0.4, P = 0.03) typical of squatting. Knee flexion negatively correlated with lumbar (r = −0.5 to −0.86, P<0.01) and pelvic flexion (r = −0.81, P<0.001). Those with curvier spines flexed significantly more at the back (r = −0.79, P=0.02) typical of stooping.

Conclusion

In summary, individuals with straight spines squatted to lift while those with curvy spines stooped, indicating that the way we move to pick up a load is associated with the shape of our spine.


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The authors declare they have no conflicts of interest.

This work was supported by a studentship granted to the University and awarded to AVP. An NHS Endowment grant provided further funding.