Computer simulation for the optimization of instrumentation strategies in adolescent idiopathic scoliosis

Majdouline, Younes; Aubin, Carl‐Éric; Sangole, Archana P.

doi:10.1007/s11517-009-0509-1

Cited by 30 publications

(26 citation statements)

References 39 publications

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“…Indeed, until now, there is no consensus on what possible initial shape of rod could result to a certain sagittal outcome. Decision-making is always based on individual surgeons' preferences and experience [33][34][35]. In this study, although rod deformation occurred, we have found a positive trend between the degree of rod deformation ∆θ and preoperative implant rod angle of curvature θ 1 at the concave side.…”

Section: Discussionmentioning

confidence: 49%

“…Optimal scoliosis surgical treatment is not always achieved due to the variability of surgeons' preferences, choice of approach, choice of instrumented level, surgeon experience and different correction objectives [33][34]. Several studies conducted biomechanical modeling to simulate various correction objectives, surgical steps and strategies.…”

Section: Introductionmentioning

confidence: 99%

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Influence of implant rod curvature on sagittal correction of scoliosis deformity

et al. 2014

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PURPOSE:To analyze the changes of implant rod angle of curvature during surgery and establish its influence on sagittal correction of scoliosis deformity. STUDY DESIGN:A retrospective analysis of the preoperative and postoperative implant rod geometry and angle of curvature was conducted.PATIENT SAMPLE: Twenty adolescent idiopathic scoliosis patients underwent surgical operation. Average age at the time of operation was 14 years. OUTCOME MEASURES:The preoperative and postoperative implant rod angle of curvature expressed in degrees was obtained for each patient. METHODS:Two implant rods were attached to the concave and convex side of the spinal deformity. The preoperative implant rod geometry was measured before surgical implantation.The postoperative implant rod geometry after surgery was measured by Computed Tomography scanner. The implant rod angle of curvature at the sagittal plane was obtained from the implant rod geometry. The angle of curvature between the implant rod extreme ends was measured before implantation and after surgery. The sagittal curvature between the corresponding spinal levels of healthy adolescents obtained by previous studies was compared to the implant rod angle of curvature to evaluate the sagittal curve correction. The difference between the postoperative implant rod angle of curvature and normal spine sagittal curvature of the corresponding instrumented level was used to evaluate over or under correction of the sagittal deformity.Page | 3 RESULTS:The implant rods at the concave side of deformity of all patients were significantly deformed after surgery. The average degree of rod deformation Δθ at the concave and convex side was 15.8 deg. and 1.6 deg., respectively. The average preoperative and postoperative implant rod angle of curvature at the concave side was 33.6 deg. and 17.8 degrees, respectively. The average preoperative and postoperative implant rod angle of curvature at the convex side was 25.5 degrees and 23.9 degrees, respectively. A significant relationship was found between the degree of rod deformation and preoperative implant rod angle of curvature (r = 0.60, p < 0.005). The implant rods at the convex side of all patients did not have significant deformation. The results indicate that the postoperative sagittal outcome could be predicted from the initial rod shape. CONCLUSIONS:Changes in implant rod angle of curvature may lead to over or under correction of the sagittal curve. Rod deformation at the concave side suggests that corrective forces acting on that side are higher than the convex side.

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Section: Discussionmentioning

confidence: 49%

Section: Introductionmentioning

confidence: 99%

Influence of implant rod curvature on sagittal correction of scoliosis deformity

et al. 2014

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“…Decision-making on the levels of instrumentation/fixation, types and number of implants, shape and size of implant rod is still dependent on individual surgeon's experience (Desroches et al, 2007;Majdouline et al, 2009). Optimal scoliosis surgical treatment is not achieved due to the variability of surgeons' preferences and different correction objectives.…”

Section: Introductionmentioning

confidence: 99%

Relationship of forces acting on implant rods and degree of scoliosis correction

Salmingo

Tadano

Fujisaki

et al. 2013

Clinical Biomechanics

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Background: Adolescent idiopathic scoliosis is a complex spinal pathology characterized as a threedimensional spine deformity combined with vertebral rotation. Various surgical techniques for correction of severe scoliotic deformity have evolved and became more advanced in applying the corrective forces. The objective of this study was to investigate the relationship between corrective forces acting on deformed rods and degree of scoliosis correction. Methods: Implant rod geometries of six adolescent idiopathic scoliosis patients were measured before and after surgery. An elasto-plastic finite element model of the implant rod before surgery was reconstructed for each patient. An inverse method based on Finite Element Analysis was used to apply forces to the implant rod model such that it was deformed the same after surgery. Relationship between the magnitude of corrective forces and degree of correction expressed as change of Cobb angle was evaluated. The effects of screw configuration on the corrective forces were also investigated. Findings: Corrective forces acting on rods and degree of correction were not correlated. Increase in number of implant screws tended to decrease the magnitude of corrective forces but did not provide higher degree of correction. Although greater correction was achieved with higher screw density, the forces increased at some level. Interpretation: The biomechanics of scoliosis correction is not only dependent to the corrective forces acting on implant rods but also associated with various parameters such as screw placement configuration and spine stiffness. Considering the magnitude of forces, increasing screw density is not guaranteed as the safest surgical strategy

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“…However, the amount of vertebral rotation and the selection of instrumented vertebrae which would allow the best detorsion may not be predicted. Computer simulation has been advocated to optimize instrumentation strategies [9]. Patient-specific finite element analyses may improve the prediction of correction mechanisms [10].…”

Section: Introductionmentioning

confidence: 99%

Sagittal balance correction of idiopathic scoliosis using the in situ contouring technique

et al. 2012

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Purpose Idiopathic scoliosis can lead to sagittal imbalance. The relationship between thoracic hyper-and hypokyphotic segments, vertebral rotation and coronal curve was determined. The effect of segmental sagittal correction by in situ contouring was analyzed. Methods Pre-and post-operative radiographs of 54 scoliosis patients (Lenke 1 and 3) were analyzed at 8 years follow-up. Cobb angles and vertebral rotation were determined. Sagittal measurements were: kyphosis T4-T12, T4-T8 and T9-T12, lordosis L1-S1, T12-L2 and L3-S1, pelvic incidence, pelvic tilt, sacral slope, T1 and T9 tilt. Results Thoracic and lumbar curves were significantly reduced (p = 0.0001). Spino-pelvic parameters, T1 and T9 tilt were not modified. The global T4-T12 kyphosis decreased by 2.1°on average (p = 0.066). Segmental analysis evidenced a significant decrease of T4-T8 hyperkyphosis by 6.6°(p = 0.0001) and an increase of segmental hypokyphosis T9-T12 by 5.0°(p = 0.0001). Maximal vertebral rotation was located at T7, T8 or T9 and correlated (r = 0.422) with the cranial level of the hypokyphotic zone (p = 0.003). This vertebra or its adjacent levels corresponded to the coronal apex in 79.6 % of thoracic curves.Conclusions Lenke 1 and 3 curves can show normal global kyphosis, divided in cranial hyperkyphosis and caudal hypokyphosis. The cranial end of hypokyphosis corresponds to maximal rotation. These vertebrae have most migrated anteriorly and laterally. The sagittal apex between segmental hypo-and hyper-kyphosis corresponds to the coronal thoracic apex. A segmental sagittal imbalance correction is achieved by in situ contouring. The concept of segmental imbalance is useful when determining the levels on which surgical detorsion may be focused.

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Computer simulation for the optimization of instrumentation strategies in adolescent idiopathic scoliosis

Cited by 30 publications

References 39 publications

Influence of implant rod curvature on sagittal correction of scoliosis deformity

Influence of implant rod curvature on sagittal correction of scoliosis deformity

Relationship of forces acting on implant rods and degree of scoliosis correction

Sagittal balance correction of idiopathic scoliosis using the in situ contouring technique

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