What Type of Orthosis is Optimal for Conservative Treatment of Lumbar Spondylolysis?: A Biomechanical Analysis.

To analyze the extent to which various types of orthoses can restrict motion of the lumbar spine and provide basic evidence regarding the optimal orthosis for conservative treatment of lumbar spondylolysis (LS), particularly. Although several orthoses have been developed and applied for LS with better outcomes for bony healing, basic data regarding which is optimal are still lacking.Ten healthy voluntary participants were included in this study. Lumbar spine range of motion (ROM) was analyzed using a three-dimensional motion capture system (NEXUS 2.2, Vicon Motion Systems Ltd., UK) under five conditions wearing no orthosis (NB) and four types of lumbar-sacral orthoses (LSO): custom-made hard LSO (HO), soft LSO supported by four aluminum stays and a custom-molded back cast-panel named "Return to Sports" braces (RS), custom-made soft LSO known as Damen type elasticity corset (DC), and off-the-shelf soft LSO.HO showed the highest restriction of motion in all directions than the others. Especially, ROM of rotation and side bending were reduced to 58.3% and 63.6% compared with NB, respectively. The other three LSOs showed significantly higher restriction in extension, rotation, and side bending than NB. In flexion and side bending, DC showed significantly higher restriction than NB.HO showed high restriction in all directions. RS showed higher restriction in extension than NB and less restriction in flexion and side bending than other custom-made LSOs. DC was the only soft LSO showing higher restriction than NB in flexion.