A novel approach to the clinical evaluation of differential kinematics of the lumbar spine

Clinical measurement of lumbar motion has traditionally been limited to range of motion (ROM). Despite this, deficits in angular velocities and accelerations are more pronounced compared to ROM in low back pain (LBP) sufferers. There is increasing interest in movement quality among manual therapists and therefore the ability to measure angular velocities and accelerations within the clinical environment is becoming increasingly important. The aims of this study were to (1) investigate the reliability of a clinic based inertial sensor system to measure ROM along with angular velocities and accelerations in low back pain sufferers; (2) introduce the feasibility and reliability of using the relationship between ROM and velocity to investigate movement trajectory and irregularity. Forty LBP sufferers completed three trials of spinal movements and lifting. The ROM curve was differentiated and double differentiated to yield angular velocities and accelerations. Repeated measures reliabilities were determined by comparisons of kinematic curves as well as peak values. ROM and angular velocity relationships were investigated for their use in describing the movement trajectory and irregularity. Results show excellent similarities of ROM and angular velocity curves and moderate-to-good similarities for angular acceleration curves. Peak value similarities were excellent with small error measurements for all variables. The quantification of ROM-angular velocity plots was reliable with small mean absolute differences in motion irregularity scores. Such a method was able to demonstrate differences in movement irregularity. This method provides clinicians with the ability to yield important additional movement related information including angular velocity, acceleration and movement irregularity. (C) 2012 Elsevier Ltd. All rights reserved.