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Panico M, Chande RD, Lindsey DP, Maria Tobia Villa T, Yerby SA, Brayda-Bruno M, Bassani T, Polly DW, Galbusera F. High-Demand Spinal Deformity With Multi-Rod Constructs and Porous Fusion/Fixation Implants: A Finite Element Study. Global Spine J 2024; 14:1328-1336. [PMID: 36421053 DOI: 10.1177/21925682221141874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
STUDY DESIGN Basic science (finite element analysis). OBJECTIVES Pedicle subtraction osteotomy (PSO) at L5 is an effective treatment for sagittal imbalance, especially in select cases of patients showing kyphosis with the apex at L4-L5 but has been scarcely investigated. The aim of this study was to simulate various "high-demand" instrumentation approaches, including varying numbers of rods and sacropelvic implants, for the stabilization of a PSO at L5. METHODS A finite element model of T10-pelvis was modified to simulate posterior fixation with pedicle screws and rods from T10 to S1, alone or in combination with an L5 PSO. Five additional configurations were then created by employing rods and novel porous fusion/fixation implants across the sacroiliac joints, in varying numbers. All models were loaded using pure moments of 7.5 Nm in flexion-extension, lateral bending, and axial rotation. RESULTS The osteotomy resulted in a general increase in motion and stresses in posterior rods and S1 pedicle screws. When the number of rods was varied, three- and four-rod configurations were effective in limiting the maximal rod stresses; values approached those of posterior fixation with no osteotomy. Maximum stresses in the accessory rods were similar to or less than those observed in the primary rods. Multiple sacropelvic implants were effective in reducing range of motion, particularly of the SIJ. CONCLUSIONS Multi-rod constructs and sacropelvic fixation generally reduced maximal implant stresses and motion in comparison with standard posterior fixation, suggesting a reduced risk of rod breakage and increased joint stability, respectively, when a high-demand construct is utilized for the correction of sagittal imbalance.
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Affiliation(s)
- Matteo Panico
- IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | | | | | - Tomaso Maria Tobia Villa
- IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | | | | | - Tito Bassani
- IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - David W Polly
- Department of Orthopedic Surgery, University of Minnesota, Minnesota, MN, USA
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Panico M, Bertoli M, Villa TMT, Galbusera F, Messori M, La Maida GA, Misaggi B, Gallazzi E. Does the anterior column realignment technique influences the stresses on posterior instrumentation in sagittal imbalance correction? A biomechanical, finite-element analysis of L5-S1 ALIF and L3-4 lateral ACR. Spine Deform 2023; 11:41-47. [PMID: 35999490 DOI: 10.1007/s43390-022-00567-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 07/30/2022] [Indexed: 10/15/2022]
Abstract
STUDY DESIGN Biomechanical finite-element study. OBJECTIVE To directly compare the biomechanical effects of two different techniques for sagittal plane correction of adult spine deformity based on the anterior longitudinal ligament (ALL) resection and use of hyperlordotic cages, namely, the anterior column realignment (ACR) in L3-4, and ALIF in L5-S1 in terms of primary stability and rod stresses using finite-element models. METHODS A finite-element model of the thoracolumbar spine was used to perform the analysis. Starting from this "intact" model, three further models were constructed through the insertion of spinal instrumentation, i.e., pedicle screws, rods and cages: 1) posterior instrumentation between T9 and S1 (referred to as "T9-S1"); 2) posterior instrumentation T9-S1 + Hyperlordotic (26°) ALIF cage in L5-S1 ("ALIF"); 3) posterior instrumentation T9-S1 + Hyperlordotic (30°) ACR cage in L3-4 ("ACR"). These models were studied by simulations applying, alternately, a pure moment of 7.5 Nm between the three planes of motion (flexion, extension, lateral bending, and bilateral axial rotation), uniformly distributed over the upper surface of the T9 thoracic vertebra. A total of 24 simulations were performed (6 per models). RESULTS All models presented a significant reduced ROM when compared to the intact model; the ROM reduction was higher both at L3-4 in the ACR model and at L5-S1 in the ALIF model. At L3-4, the ACR model had, in all cases, the lowest maximum values of Von Mises stresses on the rods, especially in flexion-extension. At L4-5, the ALIF model had the lowest stresses during flexion-extension and axial rotation, while the ACR model had the lowest stresses during lateral bending. At L5-S1, the ALIF model had, in all cases, the lowest stresses on the rods. CONCLUSIONS This finite-element study showed how both ACR at L3-4 and ALIF-ACR at L5-S1 are effective in restoring lumbar lordosis (LL), stabilizing the spine and reducing stress on posterior rods at the index level when compared to a simple fixation model. Interestingly, ALIF-ACR reduces rod stress even at L4-5 in flexion-extension and axial rotation, possibly due to a better distribution of LL, especially on the lower arch, while ACR reduces the stress at L4-5 in lateral bending, possibly thanks to the larger footprint of the cage that increases the area of contact with the lateral side of the endplates.
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Affiliation(s)
- Matteo Panico
- IRCCS Istituto Ortopedico Galeazzi, Milano, Italy.,Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico Di Milano, Milano, Italy
| | - Marco Bertoli
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico Di Milano, Milano, Italy
| | - Tomaso Maria Tobia Villa
- IRCCS Istituto Ortopedico Galeazzi, Milano, Italy.,Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico Di Milano, Milano, Italy
| | | | | | | | - Bernardo Misaggi
- U.O.C. Patologia Vertebrale E Scoliosi, ASST Gaetano Pini-CTO, Milano, Italy
| | - Enrico Gallazzi
- U.O.C. Patologia Vertebrale E Scoliosi, ASST Gaetano Pini-CTO, Milano, Italy.
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Panico M, Bertoli M, Villa TMT, Galbusera F, Messori M, La Maida GA, Misaggi B, Gallazzi E. Correction: Does the anterior column realignment technique influences the stresses on posterior instrumentation in sagittal imbalance correction? A biomechanical, finite-element analysis of L5-S1 ALIF and L3-4 lateral ACR. Spine Deform 2022; 10:1495. [PMID: 36149603 DOI: 10.1007/s43390-022-00591-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Matteo Panico
- IRCCS Istituto Ortopedico Galeazzi, Milano, Italy
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico Di Milano, Milano, Italy
| | - Marco Bertoli
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico Di Milano, Milano, Italy
| | - Tomaso Maria Tobia Villa
- IRCCS Istituto Ortopedico Galeazzi, Milano, Italy
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico Di Milano, Milano, Italy
| | | | | | | | - Bernardo Misaggi
- U.O.C. Patologia Vertebrale E Scoliosi, ASST Gaetano Pini-CTO, Milano, Italy
| | - Enrico Gallazzi
- U.O.C. Patologia Vertebrale E Scoliosi, ASST Gaetano Pini-CTO, Milano, Italy.
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Panico M, Bassani T, Villa TMT, Galbusera F. The Simulation of Muscles Forces Increases the Stresses in Lumbar Fixation Implants with Respect to Pure Moment Loading. Front Bioeng Biotechnol 2021; 9:745703. [PMID: 34881230 PMCID: PMC8645959 DOI: 10.3389/fbioe.2021.745703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 11/05/2021] [Indexed: 11/16/2022] Open
Abstract
Simplified loading conditions such as pure moments are frequently used to compare different instrumentation techniques to treat spine disorders. The purpose of this study was to determine if the use of realistic loading conditions such as muscle forces can alter the stresses in the implants with respect to pure moment loading. A musculoskeletal model and a finite element model sharing the same anatomy were built and validated against in vitro data, and coupled in order to drive the finite element model with muscle forces calculated by the musculoskeletal one for a prescribed motion. Intact conditions as well as a L1-L5 posterior fixation with pedicle screws and rods were simulated in flexion-extension and lateral bending. The hardware stresses calculated with the finite element model with instrumentation under simplified and realistic loading conditions were compared. The ROM under simplified loading conditions showed good agreement with in vitro data. As expected, the ROMs between the two types of loading conditions showed relatively small differences. Realistic loading conditions increased the stresses in the pedicle screws and in the posterior rods with respect to simplified loading conditions; an increase of hardware stresses up to 40 MPa in extension for the posterior rods and 57 MPa in flexion for the pedicle screws were observed with respect to simplified loading conditions. This conclusion can be critical for the literature since it means that previous models which used pure moments may have underestimated the stresses in the implants in flexion-extension and in lateral bending.
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Affiliation(s)
- Matteo Panico
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy.,IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - Tito Bassani
- IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - Tomaso Maria Tobia Villa
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy.,IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
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Panico M, Chande RD, Lindsey DP, Mesiwala A, Villa TMT, Yerby SA, Gallazzi E, Brayda-Bruno M, Galbusera F. Innovative sacropelvic fixation using iliac screws and triangular titanium implants. Eur Spine J 2021; 30:3763-3770. [PMID: 34562177 DOI: 10.1007/s00586-021-07006-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 08/19/2021] [Accepted: 09/21/2021] [Indexed: 11/29/2022]
Abstract
PURPOSE Sacropelvic fixation is frequently used in combination with thoracolumbar instrumentation for the correction of severe spinal deformities. The purpose of this study was to explore the effects of the triangular titanium implants on the iliac screw fixation. Our hypothesis was that the use of triangular titanium implants can increase the stability of the iliac screw fixation. METHODS Three T10-pelvis instrumented models were created: pedicle screws and rods in T10-S1, and bilateral iliac screws (IL); posterior fixation and bilateral iliac screws and triangular implants inserted bilaterally in a sacro-alar-iliac trajectory (IL-Tri-SAI); posterior fixation and bilateral iliac screws and two bilateral triangular titanium implants inserted in a lateral trajectory (IL-Tri-Lat). Outputs of these models, such as hardware stresses, were compared against a model with pedicle screws and rods in T10-S1 (PED). RESULTS Sacropelvic fixation decreased the L5-S1 motion by 75-90%. The motion of the SIJ was reduced by 55-80% after iliac fixation; the addition of triangular titanium implants further reduced it. IL, IL-Tri-SAI and IL-Tri-Lat demonstrated lower S1 pedicle stresses with respect to PED. Triangular implants had a protective effect on the iliac screw stresses. CONCLUSION Sacropelvic fixation decreased L5-S1 range of motion suggesting increased stability of the joint. The combination of triangular titanium implants and iliac screws reduced the residual flexibility of the sacroiliac joint, and resulted in a protective effect on the S1 pedicle screws and iliac screws themselves. Clinical studies may be performed to demonstrate applicability of these FEA results to patient outcomes.
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Affiliation(s)
- Matteo Panico
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, 20133, Milan, Italy. .,IRCCS Istituto Ortopedico Galeazzi, Milan, Italy.
| | | | | | - Ali Mesiwala
- Southern California Center for Neuroscience and Spine, Pomona, CA, USA
| | - Tomaso Maria Tobia Villa
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, 20133, Milan, Italy.,IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | | | - Enrico Gallazzi
- ASST Gaetano Pini: Azienda Socio Sanitaria Territoriale Gaetano Pini, Milan, Italy
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Barba N, Ignasiak D, Villa TMT, Galbusera F, Bassani T. Assessment of trunk muscle activation and intervertebral load in adolescent idiopathic scoliosis by musculoskeletal modelling approach. J Biomech 2020; 114:110154. [PMID: 33279818 DOI: 10.1016/j.jbiomech.2020.110154] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 11/19/2020] [Accepted: 11/23/2020] [Indexed: 11/16/2022]
Abstract
Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine, the aetiology and pathogenesis of which are poorly understood. Unfortunately, biomechanical data describing trunk muscle activation and intervertebral load, which can contribute to understanding the pathomechanics of the AIS spine, cannot be measured in vivo due to the invasiveness of the procedures. The present study provides the biomechanical characterization of the spinal loads in scoliotic subjects by exploiting musculoskeletal modelling approach, allowing for calculating biomechanical measures in an assigned posture. A spine model with articulated ribcage previously developed in AnyBody software was applied. The predicted outcomes were evaluated in the upright posture, depending on scoliosis severity and curve type, in a population of 132 scoliotic subjects with mild, moderate, and severe scoliosis. Radiographic-based three dimensional reconstruction of vertebral orientations and scaling of body segments and trunk muscle cross-section area guaranteed geometrical subject-specificity. Validation analysis supporting the application of the model was performed. Trunk muscles were found more activated in the convex side of the scoliotic curve, in agreement with reference in vivo measurements, with progressive increase with scoliosis severity. The intervertebral lateral shear was found positively correlated with the severity of the scoliosis, demonstrating that the transferred load is not a priori orthogonal to vertebral endplate in the frontal plane, and thus questioning the assumption of the 'follower load' approach in case of experimental or computational study on the scoliotic spine. The study opens the way for the subject-specific characterization of scoliosis in assigned loading and motion conditions.
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Affiliation(s)
- Noemi Barba
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | | | - Tomaso Maria Tobia Villa
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Fabio Galbusera
- IRCCS Istituto Ortopedico Galeazzi, Milan, Italy. LABS - Laboratory of Biological Structures Mechanics
| | - Tito Bassani
- IRCCS Istituto Ortopedico Galeazzi, Milan, Italy. LABS - Laboratory of Biological Structures Mechanics..
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Panico M, Chande RD, Lindsey DP, Mesiwala A, Villa TMT, Yerby SA, Brayda-Bruno M, Galbusera F. The use of triangular implants to enhance sacropelvic fixation: a finite element investigation. Spine J 2020; 20:1717-1724. [PMID: 32502655 DOI: 10.1016/j.spinee.2020.05.552] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 05/21/2020] [Accepted: 05/21/2020] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Long thoracolumbar fixation and fusion have become a consolidated treatment for severe spinal disorders. Concomitant sacropelvic fixation with S2 alar-iliac (S2AI) screws is frequently performed to limit instrumentation failure and pseudarthrosis at the lumbosacral junction. PURPOSE This study explored the use of triangular titanium implants in different configurations in which the implants supplemented standard sacropelvic fixation with S2AI screws in order to further increase the stability of S2AI fixation. STUDY DESIGN Finite element study. METHODS Four T10-pelvis instrumented models were built: pedicle screws and rods in T10-S1 (PED); pedicle screws and rods in T10-S1, and bilateral S2 alar-iliac screws (S2AI); pedicle screws and rods in T10-S1, bilateral S2AI screws, and triangular implants inserted bilaterally in a sacral alar-iliac trajectory (Tri-SAI); pedicle screws and rods in T10-S1, bilateral S2AI screws and two bilateral triangular titanium implants inserted in a lateral trajectory (Tri-Lat). The models were tested under pure moments of 7.5 Nm in flexion-extension, lateral bending and axial rotation. RESULTS SIJ motion was reduced by 50% to 66% after S2AI fixation; the addition of triangular titanium implants in either a SAI or a lateral trajectory further reduced it. S2AI, Tri-SAI, and Tri-Lat resulted in significantly lower stresses in S1 pedicle screws when compared to PED. Triangular implants had a protective effect on the maximal stresses in S2AI screws, especially when placed in the SAI trajectory. Sacropelvic fixation did not have any protective effect on the posterior rods. CONCLUSIONS Supplementing S2AI screws with triangular implants had a protective effect on the S2AI screws themselves, as well as the S1 pedicle screws, in the tested model. CLINICAL SIGNIFICANCE Triangular implants can substantially reduce the residual flexibility of the SIJ with respect to S2AI fixation alone, suggesting a possible role in patients needing reinforced fixation. In vivo investigation is needed to determine if these in vitro effects translate into clinically important differences.
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Affiliation(s)
- Matteo Panico
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy; IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | | | | | - Ali Mesiwala
- Southern California Center for Neuroscience and Spine, Pomona, CA, USA
| | - Tomaso Maria Tobia Villa
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
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