A E A Ochtman1, A Bisschop2, R L A W Bleys3, F C Öner4, S M van Gaalen5. 1. Department of Orthopedics, University Medical Center Utrecht, PO box 85500, 3508 GA, Utrecht, The Netherlands. a.e.a.ochtman@umcutrecht.nl. 2. Department of Orthopedics, VU University Medical Center, Amsterdam, The Netherlands. 3. Department of Anatomy, University Medical Center Utrecht, Utrecht, The Netherlands. 4. Department of Orthopedics, University Medical Center Utrecht, PO box 85500, 3508 GA, Utrecht, The Netherlands. 5. Acibadem International Medical Center, Arlandaweg 100, 1043 HP, Amsterdam, The Netherlands.
Abstract
PURPOSE: Degenerative changes of the lumbar spine lead in general to decrease of lumbar lordosis (LL). This change affects the overall balance of the spine, and when surgery is deemed, necessary restoration of the LL is considered. How this restoration can be achieved is a matter of controversy. The main purpose of this cadaveric study was to investigate the different steps of common posterior surgical techniques to understand the contribution of each successive step in restoring LL. METHODS: Ten fresh-frozen human lumbar spine specimens were used to perform a sequential correction and instrumentation with a pedicle screw construct. RESULTS: The mean LL angle measured at L3-L4 in intact condition was 12.9°; after screw insertion and compression, this increased to 13.8° (+ 7%, p = 0.04), after bilateral facetectomy to 16.3° (+ 20%, p = 0.005), after discectomy and insertion of interbody cage to 18.0º (+ 9%, p = 0.012), after resection of the lamina and the processes spinosus to 19.8° (+ 10%, p = 0.017), and after resection of the anterior longitudinal ligament to 25.4° (+ 22%, p = 0.005). CONCLUSIONS: Each step contributed statistically significant to restoration of segmental lordosis with bilateral facetectomy contributing the most in terms of percentage. LEVEL OF EVIDENCE: IV.
PURPOSE: Degenerative changes of the lumbar spine lead in general to decrease of lumbar lordosis (LL). This change affects the overall balance of the spine, and when surgery is deemed, necessary restoration of the LL is considered. How this restoration can be achieved is a matter of controversy. The main purpose of this cadaveric study was to investigate the different steps of common posterior surgical techniques to understand the contribution of each successive step in restoring LL. METHODS: Ten fresh-frozen human lumbar spine specimens were used to perform a sequential correction and instrumentation with a pedicle screw construct. RESULTS: The mean LL angle measured at L3-L4 in intact condition was 12.9°; after screw insertion and compression, this increased to 13.8° (+ 7%, p = 0.04), after bilateral facetectomy to 16.3° (+ 20%, p = 0.005), after discectomy and insertion of interbody cage to 18.0º (+ 9%, p = 0.012), after resection of the lamina and the processes spinosus to 19.8° (+ 10%, p = 0.017), and after resection of the anterior longitudinal ligament to 25.4° (+ 22%, p = 0.005). CONCLUSIONS: Each step contributed statistically significant to restoration of segmental lordosis with bilateral facetectomy contributing the most in terms of percentage. LEVEL OF EVIDENCE: IV.
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