Lumbar corsets: Their effect on three-dimensional kinematics of the pelvis

Lumbar corsets have been recommended for low back pain patients as a way of stabilizing the lumbar region, facilitating flexion movements, and reducin g pain. However, little is known about how these devices affect lumbar moti on. To determine the degree of changes in the lumbar region, our approach w as to quantify three-dimensional kinematic data of the pelvis in harness-su pported treadmill walking. Twelve healthy subjects (age=32+/-11.8 years) wa lked on a motorized treadmill at 4.5 km/h with and without wearing a lumbar corset. Three external markers overlying the sacrum were tracked by three ultrasound microphones, determining a local coordinate system, to obtain pe lvic motions in the frontal, sagittal, and transverse planes. Raw kinematic data were low-pass filtered and normalized relative to the right heel stri ke. Mean values for net angular displacements of the pelvis were calculated for each plane within the 5th and 95th percentile. The Student's t-test de monstrated significant differences (P<0.001) between the corset/no-corset c onditions in the frontal plane. An average 40% decrease in the relative pel vis up- and downward movement occurred in the frontal plane (4.1<degrees>+/ -20.9 degrees vs. 7.1 degrees+/-3.3 degrees). The analysis revealed no sign ificant differences of net angular displacements in the sagittal (2.9 degre es+/-1.4 vs. 3.4 degrees+/-1.7 degrees) and the transverse planes (4.4 degr ees+/-2.6 degrees vs. 4.3 degrees+/-2.1 degrees).