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Published on: May 31, 2017
En bloc spondylectomy reconstructions in a biomechanical in-vitro study
A C Disch1, K D Schaser, I Melcher
1Section for Musculoskeletal Tumor Surgery, Center for Musculoskeletal Surgery, Charité-University Medicine Berlin, Augustenburger Platz 1, 13353 Berlin, Germany. alexander.disch@charite.de
Summary
En bloc spondylectomy requires stabilizing adjacent spinal segments. Long posterior fixation, spanning more than one segment, is crucial for stability after vertebral resection, unlike short fixation. VBR system design showed minimal impact.
Area of Science:
- Spine surgery
- Biomechanics
- Orthopedic oncology
Background:
- En bloc spondylectomy is used for spinal tumors, but standard stabilization techniques may not apply due to complete vertebral resection.
- The biomechanical stability of different instrumentation strategies after this procedure requires investigation.
Purpose of the Study:
- To evaluate the in-vitro stability of various posterior instrumentation constructs, anterior plating, and vertebral body replacement (VBR) designs following en bloc spondylectomy.
Main Methods:
- Biomechanical testing of six human thoracolumbar spine specimens using a spine simulator.
- Eight stabilization techniques were tested, including short and long posterior instrumentation, two VBR systems (expandable cage and carbon fiber composite), and anterior plating.
- Intersegmental motion was measured under pure moment loading in three planes.
Main Results:
- Long posterior instrumentation significantly reduced motion compared to short posterior instrumentation.
- Short posterior fixation alone did not restore stability, even with anterior plating.
- VBR system design (expandable vs. non-expandable) had minimal impact on stability.
Conclusions:
- Stability after thoracolumbar en bloc spondylectomy is primarily determined by posterior fixation spanning at least one adjacent segment.
- Short posterior fixation is insufficient for restoring stability.
- Anterior plating offers limited additional stability to short constructs.