Mechanism of Action
LimiFlex: Dynamic Flexion Restriction
The LimiFlex Spinal Stabilization System resists the separation of two adjacent spinous processes through progressive tensile forces applied by fabric straps attached in a loop to dynamic titanium rods. By resisting spinous process separation, the system reduces segmental flexion and increases facet engagement, stabilizing the treated segment in flexion. Because flexion and segmental translation are coupled, segmental translation is also stabilized. Extension, rotation, and lateral bending are minimally affected. 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 |
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Cadaveric Biomechanical Testing at Loyola University of Chicago, lab of Dr. Avinash Patwardhan
LimiFlex cadaveric biomechanical testing demonstrates:
- Reduced segmental flexion Range-of-Motion (ROM)
- Increased flexion stiffness
- Increased facet engagement
- Increased stability
LimiFlex Reduces Flexion ROM and Increases Flexion Stiffness
of a Destabilized Spine
Results presented at the 17th International Meeting on Advanced Spine Techniques (Toronto, ON – July 2010)
LimiFlex Increases Facet Engagement and Reduces Segmental Translation
of a Destabilized Spine
Results Presented at the 17th International Meeting on Advanced Spine Techniques (Toronto, ON – July 2010)
The LimiFlex is designed to achieve its intended biomechanical effects while avoiding unwanted side effects. In cadaveric biomechanical testing, the device does not induce hyperextension, and the physiologic center of rotation of the treated segment is maintained.
Spinous Process Strength Testing
In addition to the kinematic assessments, Simpirica performed cadaveric spinous process strength testing to assess the safety of the device’s attachment to the anatomy. The testing demonstrated that the average loads required to break the spinous processes with a strap are several times greater than the maximum loads that the LimiFlex exerts on the bone. The results were consistent even when up to 50% of the spinous process is removed for a decompression, as well as for osteopenic or osteoporotic specimens.
Unlike other spinal instrumentation, the LimiFlex bears increased loads only when the spinous processes separate and does not bear or transmit axial compressive loads. Other spinal instrumentation must routinely bear axial compressive loads, including impulse loads generated during activities such as walking or running.1,2
For further information and copies of pre-clinical publications on the LimiFlex Spinal Stabilization System listed below please contact Simpirica Spine, Inc.
Simpirica Pre-Clinical Publications and Presentations
Fielding, Patwardhan et al. "Flexion-Restricting Stabilization System Restores Kinematics after Simulated Injury," Presented at the 17th International Meeting on Advanced Spine Techniques (IMAST), July 2010 (poster 631).
Fielding, Patwardhan et al. "Anterior Lumbar Vertebral Translation is Coupled to Segmental Flexion," Presented at the 17th International Meeting on Advanced Spine Techniques (IMAST), July 2010 (poster 601).
Fry, Patwardhan, et al. "Increasing Compressive Preload Reduces the Segmental Instability Produced by Progressive Destabilization," Presented at NASS, November 2009.
Fry, Patwardhan, et al. "Effect of Compressive Preload Magnitude on Lumbar Segment Instability After Progressive Destabilization" Presented at the 35th annual meeting of the International Society for the Study of the Lumbar Spine (ISSLS); May 2009, Miami, FL.
Parikh et al. "Effect of Lumbar Decompression Spinal Surgery on Spinous Process Strength," Presented at the 35th annual meeting of the International Society for the Study of the Lumbar Spine (ISSLS); May 2009, Miami, FL.