Finite element modeling of pedicle screw fixation considering patient-specific bone density.

Surgical instrumentation and fusion are necessary in severe cases of spinal deformity. In patients with reduced bone quality, pedicle screw fixation remains challenging due to possible loosening or pullout. The objective was to develop and validate a comprehensive finite element model of pedicle screw fixation considering patient-specific bone density.

Patient-specific biomechanical modeling of intraoperative scoliosis correction on the 2-year outcomes for thoracolumbar/lumbar vertebral body tethering.

Purpose: To biomechanically assess the influence of intraoperative correction and presenting Sanders maturity scores (SS) on growth modulation correction after 2 years in pediatric idiopathic scoliosis treated with Vertebral Body Tethering (VBT).

Methods: Lumbar VBT was simulated using patient-specific finite element models (FEMs) from 20 cases of pediatric idiopathic scoliosis (average thoracolumbar/lumbar Cobb 47°; min: 34°, max: 63°), calibrated for preoperative SS, weight, and spine flexibility. The validated FEM included lateral decubitus positioning and VBT instrumentation at the actual upper instrumented vertebra (UIV: T9-T12) and lower instrumented vertebra (LIV: L2-L4).

Increased differential rod contouring reduces the effectiveness of surgical correction in patients with adolescent idiopathic scoliosis.

Purpose: To evaluate the impact of increasing the differential precontouring angle of concave and convex rods on three-dimensional correction during posterior spinal fusion in patients with adolescent idiopathic scoliosis (AIS) and determine the threshold beyond which additional contouring yields no further correctional benefit in a computational model.

Methods: Patient-specific computational biomechanical models were developed using radiographs from 10 thoracic Lenke 1 AIS patients. Posterior instrumentation included bilateral uniaxial pedicle screws from T4 to L1 and rods of various diameters and materials.

Biomechanical analysis of 3D correction and bone-screw forces as a function of rod insertion sequence and orientation relative to the sagittal plane in adolescent idiopathic scoliosis instrumentation.

Background: In adolescent idiopathic scoliosis instrumentation, rods are typically aligned with the sagittal plane during the initial translation maneuver. Surgeons often empirically orient the rod slightly opposite to the scoliotic curve, but the optimal orientation and insertion sequence, as well as their influence on 3D correction and forces, remain unclear. This study investigates the biomechanical influence of these rod parameters on scoliosis correction.

Neural network-based multi-task learning to assist planning of posterior spinal fusion surgery for adolescent idiopathic scoliosis.

Purpose: Posterior spinal instrumentation and fusion (PSF) is the gold standard for severe adolescent idiopathic scoliosis (AIS), yet instrumentation strategies vary widely, often leading to suboptimal results. Deep learning's potential in AIS planning is underexplored.

Methods: This study trained and validated an artificial neural network multi-task learning model (NNML) using preoperative clinical and radiographic data from 189 AIS patients with Lenke 1A and 2A curves enrolled in the MIMO Clinical Trial (NCT01792609).

Multicenter validation of a surgical planning tool for lumbar vertebral body tethering simulating growth modulation over 2 years.

Purpose: Vertebral body tethering (VBT) for lumbar curves may have wider application than for thoracic curves due to greater growth potential than thoracic spine and benefits of preserved flexibility. Predicting long-term correction remains challenging, with high revision rates and complications (14-32%) including under-/over-correction, tether breakage, adding-on. This study aimed to validate a planning tool for lumbar VBT using a patient-specific finite element model (FEM) integrating mechanobiological growth modulation as a function of preoperative skeletal maturity.

Understanding the influence of cage and instrumentation strategies with oblique lumbar interbody fusion for grade I spondylolisthesis - A comprehensive biomechanical modeling study.

Background Context: Proper implant selection and placement in oblique lumbar intervertebral fusion (OLIF) are essential to achieve the best possible results for the patient. Key factors such as interbody cage length, height, angle, and material must all be carefully considered to achieve the intended results and minimize complications. Significant challenges remain in selecting the appropriate cage parameters to control spinal alignment while minimizing subsidence risk.

My orthopedic brace inventory (MOBI): a new, reliable, and valid questionnaire to identify barriers to brace adherence in adolescent idiopathic scoliosis treatment.

Purpose: Full-time wearing of an orthopedic brace has demonstrated effectiveness in limiting curve progression in adolescents with idiopathic scoliosis. However, treatment adherence is challenging, with an average wearing time of 13 h/day. Despite this issue, barriers to brace adherence have rarely been studied.

Biomechanical modeling and assessment of patient positioning to facilitate spinal deformity instrumentation.

Finite element models (FEM) were built based on clinical documentation of five AIS surgical cases to simulate patient positioning and spinal instrumentation. Various patient positioning and instrumentation configurations were simulated, and the associated corrections and screw pull-out forces were analyzed. Patient prone-positioning resulted in Cobb angle reduction of over 5°.

Genome-wide profiling of circulating microRNAs in adolescent idiopathic scoliosis and their relation to spinal deformity severity, and disease pathophysiology.

Adolescent Idiopathic Scoliosis (AIS) is the most common orthopedic condition requiring surgery, affecting 4% of adolescents. There is currently no proven method or prognostic test to identify symptomatic patients at risk of developing severe scoliosis who could benefit from growth-guided devices or minimally invasive non-fusion instrumentation surgeries. These innovative treatments must be performed at an early disease stage in younger patients to benefit from their growth potential.

Biomechanical Principles of Spinal Deformity Correction in the Thoracolumbar Spine.

Thoracolumbar spinal deformities are a pervasive condition affecting the adolescent and adult patient population. These deformities represent three-dimensional alterations in the coronal, sagittal, and transverse planes with implication on the local, regional, and global alignment. With continued studies, the importance of the overall correction on long-term outcomes has been established.

Immediate Correction of Idiopathic Scoliosis With Nighttime Braces Created by a Fully Automated Generative Design Algorithm: A Randomized Controlled Crossover Trial.

Study Design: Single-center, double-blinded, prospective crossover randomized controlled trial.

Objective: To clinically validate the efficacy of nighttime braces designed automatically by a generative design algorithm to treat idiopathic scoliosis (IS). The tested hypothesis was the clinical equivalence of immediate in-brace correction for the new automatically generated brace design versus a standard Providence-type brace.

Planar cell polarity zebrafish models of congenital scoliosis reveal underlying defects in notochord morphogenesis.

Congenital scoliosis (CS) is a type of vertebral malformation for which the etiology remains elusive. The notochord is pivotal for vertebrae development, but its role in CS is still understudied. Here, we generated a zebrafish knockout of ptk7a, a planar cell polarity (PCP) gene that is essential for convergence and extension (C&E) of the notochord, and detected congenital scoliosis-like vertebral malformations (CVMs).

Finite element analysis of distraction osteogenesis with a new extramedullary internal distractor.

Distraction osteogenesis (DO) is a bone regenerative maneuver, which is conventionally done with external fixators and, more recently, with telescopic intramedullary nails. Despite the proven effectiveness, external approaches are intrusive to the patient's life while intramedullary nailing damages the growth plates, making them unsuitable for pediatric patients. An internal DO plate fixator (IDOPF) was developed for pediatric patients to address these limitations.

Automated design of nighttime braces for adolescent idiopathic scoliosis with global shape optimization using a patient-specific finite element model.

Adolescent idiopathic scoliosis is a complex three-dimensional deformity of the spine, the moderate forms of which require treatment with an orthopedic brace. Existing brace design approaches rely mainly on empirical manual processes, vary considerably depending on the training and expertise of the orthotist, and do not always guarantee biomechanical effectiveness. To address these issues, we propose a new automated design method for creating bespoke nighttime braces requiring virtually no user input in the process.

Optimized braces for the treatment of adolescent idiopathic scoliosis: A study protocol of a prospective randomised controlled trial.

Introduction: Adolescent Idiopathic Scoliosis (AIS) is a 3D deformity of the spine that affects 3% of the adolescent population. Conservative treatments like bracing aim to halt the progression of the curve to the surgical threshold. Computer-aided design and manufacturing (CAD/CAM) methods for brace design and manufacturing are becoming increasingly used.

A novel method for assigning bone material properties to a comprehensive patient-specific pelvic finite element model using biplanar multi-energy radiographs.

The increasing prevalence of adult spinal deformity requires long spino-pelvic instrumentation, but pelvic fixation faces challenges due to distal forces and reduced bone quality. Bi-planar multi-energy X-rays (BMEX) were used to develop a patient-specific finite element model (FEM) for evaluating pelvic fixation. Calibration involved 10 patients, and an 81-year-old female test case was used for FEM customization and pullout simulation validation.

The Effect of Implant Density on Adolescent Idiopathic Scoliosis Fusion: Results of the Minimize Implants Maximize Outcomes Randomized Clinical Trial.

Background: Severe adolescent idiopathic scoliosis (AIS) can be treated with instrumented fusion, but the number of anchors needed for optimal correction is controversial.

Methods: We conducted a multicenter, randomized study that included patients undergoing spinal fusion for single thoracic curves between 45° and 65°, the most common form of operatively treated AIS. Of the 211 patients randomized, 108 were assigned to a high-density screw pattern and 103, to a low-density screw pattern.

A Novel Methodology to Estimate Bone Mechanical Properties Using Dual-Energy Imaging to Improve Pedicle Screw Fixation.

Objective: To develop a methodology to improve the representation of the mechanical properties of a vertebral finite element model (FEM) based on a new dual-energy (DE) imaging technology to improve pedicle screw fixation.

Methods: Bone-calibrated radiographs were generated with dual-energy imaging technology in order to estimate the mechanical properties of the trabecular bone. Properties were included in regions of interest in four vertebral FEMs representing heterogeneity and homogeneity, as a realistic and reference model, respectively.

The use of deep learning in medical imaging to improve spine care: A scoping review of current literature and clinical applications.

Background: Artificial intelligence is a revolutionary technology that promises to assist clinicians in improving patient care. In radiology, deep learning (DL) is widely used in clinical decision aids due to its ability to analyze complex patterns and images. It allows for rapid, enhanced data, and imaging analysis, from diagnosis to outcome prediction.

Concave rod first vs. convex rod first in AIS instrumentation with differential rod contouring: computer modeling and simulations based on ten AIS surgical cases.

Purpose: To assess biomechanical differences between AIS instrumentations using concave vs. convex rod first.

Methods: Instrumentations of ten AIS patients were simulated first with major correction maneuvers using the concave rod then with convex rod.