To test the posterior-to-anterior stiffness (PAS) of a new thoracic spine training simulator under different conditions of “fixation.”
We constructed a thoracic spine model using plastic bones and ribs mounted in a wooden box, with skin and soft tissue simulated by layers of silicone and foam. The spine segment could be stiffened with tension applied to cords running through the vertebrae and ribs. We tested PAS at 2 tension levels using a custom-built device to apply repetitive loads at the T6 spinous process (SP) and over adjacent soft tissue (TP) while measuring load and displacement. Stiffness was the slope of the force-displacement curve from 55 to 75 N.
Stiffness in the unconstrained (zero tension) condition over the SP averaged 11.98 N/mm and 6.72 N/mm over the TP. With tension applied, SP stiffness increased to 14.56 N/mm, and TP decreased to 6.15 N/mm.
Thoracic model compliance was similar to that reported for humans. The tension control system increased stiffness by 21.3% only over the SP. Stiffness over the TP was dominated by the lower stiffness of the thicker foam layer and did not change. The mannequin with these properties may be suitable for use in manual training of adjusting or PAS testing skills.
Edward Owens Jr is a Senior Research Scientist at the Dr Sid E. Williams Center for Chiropractic Research at Life University (117 Carlton Road, Savannah, GA 31401; firstname.lastname@example.org). Ronald Hosek is a Senior Research Scientist at the Dr Sid E. Williams Center for Chiropractic Research at Life University (1269 Barclay Circle, Marietta, GA 30060; email@example.com). Brent Russell is a professor at the Dr Sid E. Williams Center for Chiropractic Research at Life University (1269 Barclay Circle, Marietta, GA 30060; firstname.lastname@example.org). Address correspondence to Edward Owens Jr, 117 Carlton Road, Savannah, GA 31410; email@example.com. This article was received June 28, 2019; revised November 7, 2019; and accepted December 24, 2019.
Concept development: EO, RH, BR. Design: EO, RH, BR. Supervision: EO. Data collection/processing: EO, RH, BR. Analysis/interpretation: EO. Literature search: EO, RH, BR. Writing: EO, RH, BR. Critical review: EO, RH, BR.