Biomechanics

Reduced Segmental ROM and Increased Segmental Stiffness in Flexion

The LimiFlex™ Paraspinous Tension Band resists the separation of two adjacent spinous processes through progressive tensile forces applied by polyethylene straps attached in a loop to a pair of titanium couplers sitting on either side of the spinal midline. By resisting spinous process separation, the system reduces segmental flexion and maintains facet engagement, stabilizing the treated segment in flexion. Because flexion and segmental translation are coupled, segmental translation is also stabilized. The following animation sequence demonstrates LimiFlex™ stabilization of flexion in a human cadaveric biomechanical model.

Flexion of a destabilized spine Flexion of a spine stabilized with LimiFlex™

Flexion of a spine

Comparison of flexion in a destabilized spine and in a spine stabilized with LimiFlex™. Left: Segment “jumps” from 0-2Nm, demonstrating significant motion with minimal effort in segment destabilized with decompression and nucleotomy. Right: LimiFlex™: provides segmental flexion stiffness, restoring elastic behaviour to segment destabilized with decompression and nucleotomy. Biomechanical testing was conducted on human cadaver specimens by AG Patwardhan, Loyola University, Chicago.1

LimiFlex™ provides sagittal plane stability to destabilized spinal motion segments by

  • restoring flexion range of motion
  • increasing high flexibility zone stiffness
  • controlling sagittal translation,
  • promoting facet joint engagement in flexion.
Biomechanical testing was conducted on human cadaver specimens by AG Patwardhan, Loyola University, Chicago.1

Biomechanical testing was conducted on human cadaver specimens by AG Patwardhan, Loyola University, Chicago.1

Spinous Process Safety

Spinous processes are much stronger than the loads exerted by LimiFlex™ – even with osteopenic or osteoporotic bone, or when up to 1/2 of the spinous process is resected during decompression.

Biomechanical testing of spinous process strength for varying bone qualities. Testing was performed to failure utilizing a human cadaver spine model at the University of California, San Francisco.

Biomechanical testing of spinous process strength for varying bone qualities. Testing was performed to failure utilizing a human cadaver spine model at the University of California, San Francisco.1,2

Spinous Process Safety: Video by Todd F. Alamin, MD.3

References

1. Fielding et al. Eur Spine J. 2013 Aug 17 DOI 10.1007/s00586-013-2934-y
2. Golish et al. J Neurosurg: Spine 2012; 17:69-73
3. Todd F. Alamin, MD, orthopedic spine surgeon at Stanford University School of Medicine and co-founder of Simpirica Spine