Biomechanical Evaluation for Minimally Invasive Lumbar Decompression

摘要

Unilateral laminotomy bilateral laminotomies and laminectomy have been widely used for managing spinal stenosis syndrome and all were successful decompression methods In recent years minimally-invasive concepts have been becoming more popular due to the shorter recovery time and involve removal of smaller amounts of important structures Unilateral laminotomy was one of the minimally invasive decompression surgeries Hence it rated technically much more demanding than bilateral laminotomies and linked with more perioperative complications such as dural hematoma and dural tear However no complete kinematic data and relative biomechanical analysis for evaluating spinal instability treated with unilateral and bilateral laminotomies Therefore the purpose of this study was to compare the stability of various decompression methods and to analyze the biomechanical characteristic This study was expected to provide the selection for surgeon to decide what the decompressions methods should involve The first part of this study involved using 10 porcine lumbar spines in vitro to simulate three decompression surgeries Intact unilateral laminotomies bilateral laminotomies and laminectomies were tested using a mechanical testing machine and self-design jigs for each sample (L2–L5) During flexion and extension the spinal segment kinematics was captured using a motion tracking system and the strain was measured using a strain gauge The results indicated no significant differences in range of motion (L3–L4 and L4–L5) during flexion and extension between unilateral and bilateral laminotomies whereas statistically significant findings were observed for laminectomies The results for vertebral body strain were the same as those for range of motion with no significant differences between unilateral and bilateral laminotomies To further explore the biomechanical differences between the human and porcine lumbar spine the second part of this study entailed constructing a finite element model to analyze flexion extension lateral bending and axial rotation The model was used to simulate unilateral and bilateral laminotomies and laminectomies at L3–-L4 and L4–L5 Similar stabilities in range of motion posterior element stress and facet contact force were observed between unilateral and bilateral laminotomies This study found that the posterior longitudinal ligament during flexion and the anterior longitudinal ligament during extension were more active in bilateral than unilateral approaches (211 N vs 230 N after flexion and 338 N vs 365 N after extension) This study determined that the lumbar ligaments preserved the lumbar motion after the structures were modified If the ligaments’ function of patients were normal the bilateral laminotomies were suitable applied In summary greater spinal stability was found for laminotomies compared with laminectomies with no significant differences between bilateral and unilateral laminotomies From the biomechanical perspective bilateral laminotomies seem to maintain stability similar to that of unilateral laminotomies in short-term follow-ups

獎項日期	2016 3月 15
原文	English
監督員	Chih-Han Chang (Supervisor)