Related Experiment Video
Updated: Jun 23, 2026
Subject-specific Musculoskeletal Model for Studying Bone Strain During Dynamic Motion
Published on: April 11, 2018
Biomechanical simulation of long-term performance of a tendon-based spinal stabilization (VPX)
Jana Felicitas Schader1,2,3, Oliver Wigger4, Marie-Rosa Fasser4
1Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland. jana.schader@balgrist.ch.
Purpose:
Vertebropexy (VPX) is a purely tendon-based fixation technique of the lumbar spine. It stabilizes the segment in flexion, without immobilizing it in other directions, and therefore might biomechanically address some shortcomings of both spinal fusion and decompression-only surgery. This newly developed cyclic testing setup evaluates the ability of VPX to maintain flexion restriction under long-term biomechanical loading.
Methods:
Five spinal segments of three cadaveric human lumbar spines were selected for testing. VPX was performed using a human peroneus longus tendon allograft, looped twice around the spinous processes and secured with a Prusik knot. Each segment underwent load-controlled flexion-extension (FE) testing in five conditions: native (intact), after decompression (deco-pre, bilateral laminorecessotomy), after VPX (VPX-pre), after long-term cyclic simulation (VPX-post), and after removal of VPX (deco-post). Long-term behavior was simulated using the Dynamic Spine Simulator (DSS), applying 46,800 cycles in the three principal motion directions (FE, lateral bending (LB), axial rotation (AR)).
Results:
Compared to the paired decompressed state (deco-pre), median flexion immediately after VPX decreased to 0.5% [25th-75th percentile: - 26.3% to 12.9%]. Following the controlled cyclic durability simulation, VPX limited median flexion to 40.0% [4.2%-54.0%] relative to its decompressed state (deco post).
Conclusions:
This cadaveric proof-of-concept study demonstrates that VPX maintains stabilizing function following cyclic loading. Immediately after decompression, pre-tensioning effectively restricts flexion. Following controlled cyclic durability simulation, this restriction partially attenuates while preserving a net stabilizing effect relative to the decompressed state. These findings support VPX as a biomechanically reasonable dynamic ligamentous restraint that warrants further investigation in larger cadaveric samples and ultimately in vivo validation.
