RT Journal Article
SR Electronic
T1 A compliant-mechanism approach to achieving specific quality of motion in a lumbar total disc replacement
JF International Journal of Spine Surgery
JO Int J Spine Surg
FD International Society for the Advancement of Spine Surgery
SP 78
OP 86
DO 10.1016/j.ijsp.2012.02.002
VO 6
A1 Peter A. Halverson
A1 Anton E. Bowden
A1 Larry L. Howell
YR 2012
UL http://ijssurgery.com//content/6/78.abstract
AB Background The current generation of total disc replacements achieves excellent short- and medium-term results by focusing on restoring the quantity of motion. Recent studies indicate that additional concerns (helical axes of motion, segmental torque-rotation behavior) may have important implications in the health of adjacent segments as well as the health of the surrounding tissue of the operative level. The objective of this article is to outline the development, validation, and biomechanical performance of a novel, compliant-mechanism total disc replacement that addresses these concerns by including them as essential design criteria.Methods Compliant-mechanism design techniques were used to design a total disc replacement capable of replicating the moment-rotation response and the location and path of the helical axis of motion. A prototype was evaluated with the use of bench-top testing and single-level cadaveric experiments in flexion-extension, lateral bending, and axial torsion.Results Bench-top testing confirmed that the moment-rotation response of the disc replacement matched the intended design behavior. Cadaveric testing confirmed that the moment-rotation and displacement response of the implanted segment mimicked those of the healthy spinal segment.Conclusions Incorporation of segmental quality of motion into the foundational stages of the design process resulted in a total disc replacement design that provides torque-rotation and helical axis–of–motion characteristics to the adjacent segments and the operative-level facets that are similar to those observed in healthy spinal segments.