A novel distractive and mobility-enabling lumbar spinal orthosis

PURPOSE: Lumbar spinal orthoses are often used as non-surgical treatment and serve to support the spine and alleviate low back pain. More recently, dynamic orthoses claiming to decompress the spine have been introduced. A previously developed prototype of dynamic mobility orthosis (DMO1) was designed that provided a distractive load across the lumbar spine but required higher sagittal bending moments and was unable to maintain spinal off-loading throughout extended ranges of movement. The objective was to design a new orthosis (DMO2) that reduced bending moment buildup and sustained spinal off-loading throughout daily living ranges of flexion and extension movement. METHODS: A mechanical analog upper torso model and programmable robotic testing platform were used to design features of DMO2: a mobility-enabling component and a distractive force component. Test conditions for DMO2 were 300 N of applied vertical torso load over a range of 25° flexion to 10° extension. Loads carried by the brace were determined throughout flexion and extension ranges. Applied moments to the upper torso model and transferred moments to the spine were measured. The difference in applied and transferred moments represented brace moment effects. RESULTS: The DMO2 prototype improved spinal off-loading capacity from 172 N to 290 N at end-range flexion and from 247 N to 293 N at end range extension compared to the original DMO1 prototype. End-range applied moments (flexion-DMO1: 32.4 Nm/DMO2: 21.7 Nm; extension-DMO1: 15.0 Nm/DMO2: 10.9 Nm) and brace moments (flexion-DMO1: 18.6 Nm/DMO2: 6.6 Nm; extension-DMO1: 15.0 Nm/DMO2: 4.4 Nm) were also reduced. CONCLUSIONS: A novel dynamic spinal orthosis was designed that maintained spinal off-loading throughout extended ranges of flexion and extension movement without buildup of adverse bending moments.