Werner Schmoelz1, Sabrina Sandriesser2, Oded Loebl3, Marlies Bauer4, Dietmar Krappinger2. 1. Medical University of Innsbruck, Dept. of Trauma Surgery, Innsbruck, Austria. Electronic address: werner.schmoelz@i-med.ac.at. 2. Medical University of Innsbruck, Dept. of Trauma Surgery, Innsbruck, Austria. 3. NLT Spine, Kfar Saba, Israel. 4. Medical University of Innsbruck, Division of Clinical and Functional Anatomy, Dept. of Anatomy, Histology and Embryology, Innsbruck, Austria.
Abstract
BACKGROUND: There are various techniques and approaches for lumbar interbody fusion differing in access, cage type and type of supplemental posterior instrumentation. While a transforaminal access usually includes a hemifacetectomy, the facet joint can be preserved with a more lateral extraforaminal access. The supplemental posterior instrumentation required for both fusion techniques is still debated. The purpose of the present study was to compare primary stability of the two accesses for two different cage types with none, unilateral and bilateral supplemental posterior instrumentation. METHODS: Six monosegmental lumbar functional spinal units (FSUs) were included in each of the two groups, and subjected to a flexibility test. As cages, a newly designed cage was compared to a standard cage in the following states: (a) native, (b) stand-alone cage, (c) bilateral internal fixator, (d) unilateral internal fixator, (e) unilateral facetectomy+bilateral internal fixator, (f) unilateral facetectomy+unilateral internal fixator and (g) unilateral facetectomy with stand-alone cage. For comparison the range of motion was normalized to the native state and the effects of the facetectomy, cage type, and supplemental instrumentation was compared. FINDINGS: Within the subject comparison showed a significantly higher flexibility for the unilateral facetectomy in all motion directions (p<0.001). In between subject comparison showed a significant effect of cage type on flexibility in flexion/extension (p=0.002) and lateral bending (p=0.028) but not in axial rotation (p=0.322). The type of supplemental posterior fixation had a significant effect on the flexibility in all motion directions (stand-alone>unilateral fixator>bilateral fixator). INTERPRETATION: Cage design and approach type are affecting the primary stability of lumbar interbody fusion procedures while the type of posterior instrumentation is the most influencing factor.
BACKGROUND: There are various techniques and approaches for lumbar interbody fusion differing in access, cage type and type of supplemental posterior instrumentation. While a transforaminal access usually includes a hemifacetectomy, the facet joint can be preserved with a more lateral extraforaminal access. The supplemental posterior instrumentation required for both fusion techniques is still debated. The purpose of the present study was to compare primary stability of the two accesses for two different cage types with none, unilateral and bilateral supplemental posterior instrumentation. METHODS: Six monosegmental lumbar functional spinal units (FSUs) were included in each of the two groups, and subjected to a flexibility test. As cages, a newly designed cage was compared to a standard cage in the following states: (a) native, (b) stand-alone cage, (c) bilateral internal fixator, (d) unilateral internal fixator, (e) unilateral facetectomy+bilateral internal fixator, (f) unilateral facetectomy+unilateral internal fixator and (g) unilateral facetectomy with stand-alone cage. For comparison the range of motion was normalized to the native state and the effects of the facetectomy, cage type, and supplemental instrumentation was compared. FINDINGS: Within the subject comparison showed a significantly higher flexibility for the unilateral facetectomy in all motion directions (p<0.001). In between subject comparison showed a significant effect of cage type on flexibility in flexion/extension (p=0.002) and lateral bending (p=0.028) but not in axial rotation (p=0.322). The type of supplemental posterior fixation had a significant effect on the flexibility in all motion directions (stand-alone>unilateral fixator>bilateral fixator). INTERPRETATION: Cage design and approach type are affecting the primary stability of lumbar interbody fusion procedures while the type of posterior instrumentation is the most influencing factor.
Authors: Jorge Felipe Ramírez León; Álvaro Silva Ardila; José Gabriel Rugeles Ortíz; Carolina Ramírez Martínez; Gabriel Oswaldo Alonso Cuéllar; Jefferson Infante; Kai-Uwe Lewandrowski Journal: J Spine Surg Date: 2020-01
Authors: Conor P Lynch; Elliot D K Cha; Augustus J Rush Iii; Caroline N Jadczak; Shruthi Mohan; Cara E Geoghegan; Kern Singh Journal: Neurospine Date: 2021-12-31