Giuditta Salvi1,2, Carl-Eric Aubin3,4, Franck Le Naveaux1,2, Xiaoyu Wang1,2, Stefan Parent2. 1. Department of Mechanical Engineering, Polytechnique Montreal, P.O. Box 6079, Downtown Station, Montreal, QC, H3C 3A7, Canada. 2. Research Center, Sainte-Justine University Hospital Center, 3175, Cote Sainte-Catherine Road, Montreal, QC, H3T 1C5, Canada. 3. Department of Mechanical Engineering, Polytechnique Montreal, P.O. Box 6079, Downtown Station, Montreal, QC, H3C 3A7, Canada. carl-eric.aubin@polymtl.ca. 4. Research Center, Sainte-Justine University Hospital Center, 3175, Cote Sainte-Catherine Road, Montreal, QC, H3T 1C5, Canada. carl-eric.aubin@polymtl.ca.
Abstract
PURPOSE: Biomechanical analysis of Ponte (PO) and pedicle subtraction osteotomies (PSO) in kyphotic deformity instrumentation. METHODS: Patient-specific biomechanical model was used to computationally simulate seven hyperkyphotic instrumentation cases with three osteotomy strategies-1-level PSO, 3-level PO, or 6-level PO; forces within the instrumented spine were assessed and results were analyzed through rANOVA tests. RESULTS: Corrections with multi-level PO were close to those with one-level PSO. In upright position, average implant forces were from 225 to 280 N and rod bending moments were around 10 Nm with no significant difference between the three strategies (p < 0.05). In simulations of 30° flexion, rod bending moments increased by 38, 2, and 8 %, implant forces increased by 28, 23 and 26 % for the 1-level PSO, 3-level PO, and 6-level PO, respectively. Correction per vertebral level was smaller than the maximum correction allowed by PO and PSO. CONCLUSIONS: Multi-level PO allows similar kyphotic correction to 1-level PSO in spinal deformities with mixed indications for PO and PSO. Loads on the instrumentation constructs in PSO were higher than multi-level PO and higher in 6-level PO than 3-level PO. High loads were located more on the osteotomy sites. The rod shape should be adapted to the anticipated spine correction on the osteotomy sites.
PURPOSE: Biomechanical analysis of Ponte (PO) and pedicle subtraction osteotomies (PSO) in kyphotic deformity instrumentation. METHODS:Patient-specific biomechanical model was used to computationally simulate seven hyperkyphotic instrumentation cases with three osteotomy strategies-1-level PSO, 3-level PO, or 6-level PO; forces within the instrumented spine were assessed and results were analyzed through rANOVA tests. RESULTS: Corrections with multi-level PO were close to those with one-level PSO. In upright position, average implant forces were from 225 to 280 N and rod bending moments were around 10 Nm with no significant difference between the three strategies (p < 0.05). In simulations of 30° flexion, rod bending moments increased by 38, 2, and 8 %, implant forces increased by 28, 23 and 26 % for the 1-level PSO, 3-level PO, and 6-level PO, respectively. Correction per vertebral level was smaller than the maximum correction allowed by PO and PSO. CONCLUSIONS: Multi-level PO allows similar kyphotic correction to 1-level PSO in spinal deformities with mixed indications for PO and PSO. Loads on the instrumentation constructs in PSO were higher than multi-level PO and higher in 6-level PO than 3-level PO. High loads were located more on the osteotomy sites. The rod shape should be adapted to the anticipated spine correction on the osteotomy sites.
Authors: Justin S Smith; Christopher I Shaffrey; Christopher P Ames; Jason Demakakos; Kai-Ming G Fu; Sassan Keshavarzi; Carol M Y Li; Vedat Deviren; Frank J Schwab; Virginie Lafage; Shay Bess Journal: Neurosurgery Date: 2012-10 Impact factor: 4.654
Authors: Andy L Anderson; Terence E McIff; Marc A Asher; Douglas C Burton; R Christopher Glattes Journal: Spine (Phila Pa 1976) Date: 2009-03-01 Impact factor: 3.468