Date of Award


Document Type


Degree Name

Master of Science (MS)


Biomedical Engineering



Research Advisor

Denis J. DiAngelo, Ph.D.


Richard J. Kasser, Ph.D., M.S., B.S; William M. Mihalko, M.D., Ph.D.


Low Back Pain, Orthosis, Synthetic Spine


Low back pain (LBP) is highly prevalent in all walks of life. Standard conservative treatment methods may work for some, but others go on to have spinal injections, opioids, or surgical procedures to alleviate pain. The Distractive and Mobility-Enabling Orthosis (DMO) was developed to meet the need for a conservative, drug-free treatment method. In this research, the low back support test protocol for evaluating DMO success was upgraded with a new synthetic lumbar spine model. The latest generation of the DMO project was then evaluated using the new system in a laboratory setting and on a pilot physical therapy patient.First, a biomechanical evaluation study of the new full-length synthetic lumbar spine model was performed to validate its use in the low back support test protocol. Markers placed at each vertebral body level enabled the local and global instantaneous axis of rotation of each spinal segment to be defined. Combined with moment data, the moment-rotational stiffness properties was compared to similar published data from other in vitro and in vivo studies of the lumbar spine. These comparisons provided validation and justification for using the synthetic model in the low back support test protocol. The design of the fourth generation (DMO4) is then detailed. DMO4 borrowed some characteristics from previous generations but was modified to lower the complexity of the parts and increase user comfort. DMO4 utilized hip and torso belts to secure itself to the patient. A distractive force applied via gas springs on the lateral sides of the belts separated the belts in order to offload the lumbar spine. DMO4 reduced the side profile, reduced the component count by half, and redesigned the torso belt to be more conforming to patient anatomy.DMO4 was then evaluated with the low back support test protocol that was set to match daily living activities (DLAs) and offload an average human torso weight. Placed under a 150N vertical load, DMO4 successfully offloaded the lumbar spine in upright stance through 25° of flexion and 10° of extension. DMO4 was also successful at providing unconstrained axial rotation beyond the range required for DLAs. Pilot data of a physical therapy patient with low back pain was ascertained. The patient wore the DMO during six physical therapy sessions over a four week period. At each session, the patient’s pain score significantly dropped to a pain rating score of one and the modified Oswestry Disability Index also saw a reduction.




2019-022-Hoyer-DOA.pdf (404 kB)
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