Article
Correlation between different instrumentation variants and the degree of destabilisation in treating cervical spondylotic spinal canal stenosis – a biomechanical investigation
Zusammenhang zwischen intraoperativer Destabilisierung und verschiedenen Instrumentierungsvarianten zur Behandlung der spondylotischen zervikalen Spinalkanalstenose – eine biomechanische Studie
Search Medline for
Authors
-
Ingo Fiss
- Universitätsmedizin Göttingen, Neurochirurgie, Göttingen, Deutschland
-
Dorothee Mielke
- Universitätsmedizin Göttingen, Neurochirurgie, Göttingen, Deutschland
-
Veit Rohde
- Universitätsmedizin Göttingen, Neurochirurgie, Göttingen, Deutschland
-
Christoph Schilling
- Aesculap AG, Biomechanical Research, Tuttlingen, Deutschland
| Published: | May 8, 2019 |
|---|
Outline
Text
Objective: Unilateral hemilaminectomy and bilateral decompression was proposed as an alternative decompressive procedure in patients with spondylotic cervical myelopathy (SCM) with or without radiculopathy. Despite promising clinical results, the destabilizing effect especially if combined with foraminotomy is unknown. This biomechanical study investigates under which circumstances lateral mass screw fixation should follow unilateral hemilaminectomy and bilateral decompression.
Methods: Six human C2–C7 cervical specimens, instrumented from C3 to C6, were tested under various segment conditions: native (NAT), unilateral hemilaminectomy (UH) with bilateral decompression (BD) +/- fusion (BDZ/BDF), UH with BD and unilateral foraminotomy +/- fusion (UFZ/UFF), UH with BD and bilateral foraminotomy +/- fusion (BFZ/BFF), and laminectomy +/- fusion (LAZ/LAF). For each segment condition, in vitro tests were performed using a spinal simulator and an applied load of ±2.5 Nm. The 3-D-kinematics of the three main loading directions [flexion–extension (FE), lateral bending (LB), and axial rotation (AR)] were measured with an ultrasonic motion analysis system. Analysis of variance followed by a post hoc test was used to determine differences under the specific segment conditions to assess the parameters range of motion (ROM) and neutral zone (NZ).
Results: For FE, the total ROM of BDZ (-9.3% difference to NAT), UFZ (-7.1%), BFZ (-3.7%) and LAZ (-1.4%) remained at the level of native (p>0.74), whereas the instrumentations BDF (-61.3%), UFF (-57.3%), BFF (-55.3%) and LAF (-54.4%) led to significant reductions (p<0.01) without significant differences between BDF, UFF, BFF, and LAF, respectively (p>0.70). Results of similar significance were found with LB. For AR, the effect of stabilization in all conditions was far less pronounced, but had the same tendency seen for FE and AR. The results for the NZ showed equivalent values as that for ROM.
Conclusion: The degree of stabilization was as expected for the single segment conditions, neither a significant effect of stabilization or destabilization for BDZ, UFZ, BFZ and LAZ but a substantial stabilization for BDF, UFF, BFF and LAF. No significant differences were seen among the single instrumented and non-instrumented conditions. BDZ could be a new treatment option for less invasive decompression for multilevel SCM in patients with lordotic cervical alignment and absence of segmental instability. Later augmentation to UFF or BFF offers the same stability as classical LAF.
