Predicting Strategy of Lumbar Belts Mechanical Performance at Design Stage

Low back pain is a pain felt in the lumbar region of the spine. Among a large series of care strategies, lumbar belt might be used to treat this pathology. Several clinical trials have shown the efficiency of lumbar belts [1]. Despite the high quantity of affected patients each year (about 80 % of the French population have /will suffer back pain in their life), few authors investigated the mechanism of action of belts. It is usually reported that the main mechanical effect of a lumbar belt is the pressure applied on the trunk. This pressure on the abdominal skin and muscles induce an increase of intra-abdominal pressure, a decrease of intra-discal pressure, and a proprioceptive reaction of the posture. Unfortunately, the link between the textile characteristics, the belt design and the pressure applied on the trunk has been poorly studied. Recently, Bonnaire [2] proposed a clinical study using optical methods and pressure map sensors; Munoz [3] proposed a detailed finite element model, closely linked to medical imaging showing the load release in the intervertebral disc, but resorting to a clinical study is a tedious task, and some early stage information should be of great help when designing new belts. The purpose of this communication is an assessment of the applied pressure by a lumbar belt onto the trunk from the mechanical properties of fabrics and the trunk shape. It gives a way to estimate the mechanical efficiency of belts at the design stage.