Hip and lumbar motion: Is there a correlation between flexion and functional tasks?

Abstract

Background: It is common for patients with spinal pain to report evoked pain, associated with a variety of everyday tasks. Despite this, the assessment of an individual with spinal pain usually involves the completion of movements in the cardinal planes, for example flexion and extension. The relationship between these cardinal motions and more functional tasks is yet to be established. The aim of this study was to explore the relationship between flexion and more functional everyday sagittal tasks. Methods: Fifty three participants were recruited for this study (age 29.4 years [SD=6.5], weight 75.3 kg [SD=16.4] and height 1.7 m [SD=15.4]). Four daisy-chained accelerometers were attached to the skin over the S1, L3, T12 and lateral thigh. Each sensor provided absolute orientation with respect to gravity, which was used to determine tilt in the sagittal plane. Relative angles between adjacent sensors were used to quantify the motion for the hip, lower lumbar and upper lumbar spine. Ratios between peak values were calculated by dividing one regional peak ROM by another, quantifying regional contribution to motion. Pearson correlation coefficients were used to explore the relationship between the movements of flexion, lifting, stand-to-sit and sit-to-stand. Results: Strong correlations for range of motion are reported between flexion and lifting for the lower-lumbar spine (R2=0.83) and all regions during stand-to-sit and sit-to-stand (R2=0.84–0.92). Strong correlation is also noted between flexion and lifting for hip/lower-lumbar spine ratio (0.84). No tasks were highly correlated for velocity (R2=0.01–0.72). Conclusions: The lower-lumbar spine appears to demonstrate a relationship between flexion and lifting. However, with the exception of stand-to-sit and sit-to-stand, no other strong correlations between regional range-of-motion, velocity and ratio for a series of sagittal tasks were observed. Implications: These findings suggest that each functional task is distinct using a differing degree of range of motion, velocity and relative motion at the lumbar spine and hip. It is recommended that clinicians explore more than just the cardinal planes of motion in the examination of the spine, as these do not demonstrate the same kinematics as more functional tasks.