Applications of digital technology for the morphological study of C3–C7 vertebral arch pedicle in children

Background: This study aims to investigate the morphological characteristics and developmental patterns of the vertebral arch pedicle (VAP) in the lower cervical vertebrae of children, and to subsequently help guide the implantation of the pedicle screw. Materials and methods: The cervical vertebral multi-slice computed tomography (MSCT) data of 60 paediatric patients aged 4–12 years were collected and grouped. A reconstructed 3-dimensional model measured the following: pedicle width (PW), pedicle height (PH), pedicle osseous channel (POCL), pedicle transverse angle (PTA, namely the E angle), and pedicle sagittal angle (PTA, namely the F angle). Results: We calculated the ratio of PW/PH (I value) to assess the statistical difference between age groups and segments. The PW, PH, POCL, and E angles exhibited an overall increasing trend with increasing age. The PW, PH, and POCL of each vertebra in group C showed statically significant differences compared to groups A and B (p < 0.05). The PW of different vertebral sequences in each group showed a gradually increasing trend. The intervertebral F angle among different groups showed the biggest difference, a change from positive values to negative values gradually, among which the negative value of C7’s F angle was the largest. The I value exhibited an overall decreasing trend with increasing age. Conclusions: The morphological characteristics and development of the different pedicle segments exhibited obvious patterns. In the lower cervical vertebrae of children over 7 years of age, the vertebrae had the feasibility for the implantation of pedicle screws

Precision and safety of Multilevel Cervical Transpedicular Screw Fixation with 3D Patient-Specific Guides; A Cadaveric Study

The aim is to design a patient-specific instrument (PSI) for multilevel cervical pedicle screw placement from C2 to C7, as well as verifying reliability and reproducibility. Computed tomography (CT) scans were obtained from 7 cadaveric cervical spines. Using Mimics software, semiautomatic segmentation was performed for each cervical spine, designing a 3D cervical spine bone model in order to plan transpedicular screw fixation. A PSI was designed according to the previously cited with two cannulated chimneys to guide the drill. The guides were 3D printed and surgeries performed at the laboratory. Postoperative scans were obtained to study screw placement. Sixty-eight transpedicular screws were available for study. 61.8% of all screws were within the pedicle or partially breached <4 mm. No differences were observed between cervical levels. None of these screws had neurovascular injury. Of the 27 screws with a grade 3 (screw outside the pedicle; 39.7%), only 2 had perforation of the transverse foramen and none of them would have caused a neural injury. In conclusion, multilevel PSI for cervical pedicle screw is a promising technology that despite showing improvements regarding free-hand technique requires further studies to improve the positioning of the PSI and their accuracy

Recent trends, technical concepts and components of computer-assisted orthopedic surgery systems: A comprehensive review

Computer-assisted orthopedic surgery (CAOS) systems have become one of the most important and challenging types of system in clinical orthopedics, as they enable precise treatment of musculoskeletal diseases, employing modern clinical navigation systems and surgical tools. This paper brings a comprehensive review of recent trends and possibilities of CAOS systems. There are three types of the surgical planning systems, including: systems based on the volumetric images (computer tomography (CT), magnetic resonance imaging (MRI) or ultrasound images), further systems utilize either 2D or 3D fluoroscopic images, and the last one utilizes the kinetic information about the joints and morphological information about the target bones. This complex review is focused on three fundamental aspects of CAOS systems: their essential components, types of CAOS systems, and mechanical tools used in CAOS systems. In this review, we also outline the possibilities for using ultrasound computer-assisted orthopedic surgery (UCAOS) systems as an alternative to conventionally used CAOS systems.Web of Science1923art. no. 519

Comportamiento biomecánico de la columna vertebral lumbopélvica deformada postquirúrgica

ilustracionesBased on literature, one of the common lumbar spine disorders reported is the isthmic high-grade spondylolisthesis (HGS), and there is no consensus on its surgical treatment selection. Thus, the present thesis aims to evaluate from an engineering point of view the influence of the fixation configuration for deformed or fractured spine surgery on the stabilization, biomechanical behavior, and stress state of the post-surgical lumbo-pelvic spine, providing a useful source of information for surgical planning and decision making. To evaluate the pathology as HGS (as literature-based selected case of study of deformed spine), a patient specific lumbosacral spine model was obtained with Scalismo and CAD modeling and used as a base to recreate a HGS condition. The diagnosis was made based on clinical literature and consisted of a lumbosacral spine with grade 3 isthmic spondylolisthesis, low dysplasia (L5 rectangular), an unbalanced spine (C7PL in front of FH), and a retroverted pelvis (low SS/high PT, vertical sacrum). Fusion In situ (FIS) with laminotomy and Lumbar interbody fusion (LIF) with reduction and laminotomy techniques were identified as suggested treatments, based on the Mac-Thiong classification scheme and clinical reports. Six variations of each fixation technique, involving adding or removing screws by spine level, were defined as possible instrument configurations, and compared. Based on the case of study and geometrical model, biomechanical Finite element models were developed to evaluate the mechanical response of HGS lumbosacral spine treated with FIS and LIF techniques, along with the proposed configurations. Thirteen models, divided into two groups (FIS and LIF models), were developed as variations of FIS and LIF base models. The spine mesh was built up in Abaqus from the vertebrae, supported by BCPD morphing process. To simulate the mechanical conditions of the surgical procedure in the two groups of FIS and LIF models, Swelling, Reduction/ Displacement, and Fixation standing steps were defined. A comparison between variations by level in the FIS and LIF instrumentation configurations for HGS was developed using FEM. The results obtained can be used to establish which levels are required to fix the system while ensuring the safety of both the biological systems and the instrumental. For model validation, a comparison of FIS and LIF models with experimental, numerical, and clinical outcomes reported in the literature is suggested as an alternative.Con base en la literatura, uno de los trastornos comunes de la columna lumbar reportados es la espondilolistesis ístmica de alto grado (HGS), y no existe un consenso sobre su selección de tratamiento quirúrgico. Por lo tanto, la presente tesis tiene como objetivo evaluar, desde una visión ingenieril, la incidencia de la configuración de fijación para cirugía de columna vertebral deformada o fracturada sobre la estabilización, comportamiento biomecánico y estado de esfuerzos de la columna vertebral lumbo-pélvica postquirúrgica, proporcionando una fuente útil de información en la planificación y toma de decisiones quirúrgicas. Para evaluar una patología como HGS (como un caso de estudio de columna deformada seleccionado basado en la literatura), se obtuvo un modelo de columna lumbosacra de paciente específico utilizando el software Scalismo y modelado CAD, y se utilizó como base para recrear una condición de HGS. El diagnóstico se basó en la literatura clínica y consistió en una columna lumbosacra con espondilolistesis ístmica de grado 3, displasia baja (L5 rectangular), una columna desbalanceada (Línea de gravedad delante de la cabeza del fémur) y una pelvis retroversa (Inclinación sacra baja, inclinación pélvica alta, sacro vertical). Las técnicas de fusión in situ (FIS) con laminotomía y fusión intervertebral lumbar (LIF) con reducción y laminotomía se identificaron como los tratamientos sugeridos, basados en el esquema de clasificación de Mac-Thiong y reportes clínicos. Se definieron seis variaciones de cada técnica de fijación, que implicaban agregar o quitar los tornillos de columna por nivel, como posibles configuraciones de instrumentación y se compararon entre sí. Basándose en el caso de estudio y el modelo geométrico, se desarrollaron modelos biomecánicos de elementos finitos para evaluar la respuesta mecánica de la columna lumbosacra HGS tratada con las técnicas FIS y LIF, junto con las configuraciones propuestas. Se desarrollaron trece modelos divididos en dos grupos (modelos FIS y LIF) como variaciones de los modelos FIS y LIF base. La malla de la columna se construyó en Abaqus a partir de las vértebras, apoyado por el proceso de transformación de malla BCPD. Para simular las condiciones mecánicas del procedimiento quirúrgico en los dos grupos de modelos FIS y LIF, se definieron las etapas de estabilización (estado de hinchamiento de discos intervertebrales), reducción/ desplazamiento y fijación. Se desarrolló un comparativo entre las variaciones por nivel en las configuraciones de instrumentación FIS y LIF para HGS mediante el uso del método de elementos finitos (MEF). Los resultados obtenidos pueden ser utilizados para establecer qué niveles son necesarios para fijar el sistema y, al mismo tiempo, asegurar la seguridad tanto de los sistemas biológicos como de la instrumentación. Como alternativa para la validación del modelo, se propone una comparación de los modelos FIS y LIF con resultados experimentales, numéricos y clínicos reportados en la literatura. (texto tomado de la fuente)MaestríaMagíster en Ingeniería MecánicaBiomecánicaÁrea Curricular de Ingeniería Mecánic

In vitro comparison of a new stand-alone anterior lumbar interbody cage device with established fixation techniques

Around 70% of the population in the United States experience low back pain at some point of their lives, of these 4% underwent surgical intervention on the lumbar spine to relieve the pain. Spinal arthrodesis, i.e. joint fusion, is beneficial in many cases as the final option for patients suffering from certain types of low back pain (LBP). In order to promote solid fusion across a decompressed spinal segment, interbody spacers/cages are used with and without posterior instrumentation to provide an initial rigid fixation of the segment. In this study three fresh/frozen human cadaveric lumbar spines were used. Each lumbar spine was dissected into two Functional Spinal Units (FSUs, L3-L4 and L5-S1) making a total of 6 motion segments. The objective of this study was to evaluate the biomechanical behavior of a new stand-alone anterior lumbar interbody device, by assessing its performance in terms of FSU motion in comparison with the intact FSU and FSUs additional posterior fixation (i.e., facet bolts and pedicle screws). Descriptive statistics and analysis of variance (ANOVA) was used to determine if the differences between the different treatment groups are significant or not. Statistical analysis was also used to determine the contribution of the supplemental fixation for the anterior interbody fusion device (AFD) system

Effects of Biologics on Pedicle Screw Fixation in a Sheep Model: Histological and Biomechanical Analysis

Objective: Osteoinductive recombinant human bone morphogenetic protein (rhBMP–2) was delivered on an absorbable collagen sponge (ACS) within a novel titanium screw implant in an IACUC approved non–osteoporotic ovine spine model. Biomechanical pull–out strength, undecalcified histology, microradiography, and quantitative histomorphometry were used to assess effects of augmentation with rhBMP–2 on the holding power and peri–implant bone formation. Methodology: rhBMP–2 (0.43 mg/ml) soaked ACS was placed within and around cannulated and fenestrated titanium pedicle screw implants. Sixty–four implants were randomly divided into 4 treatment groups (n=16 each). Biomechanical pull–out testing was done on half of the screws (n=32) to determine the pull–out strength, stiffness, and energy to failure. For histology, half of the implants were sectioned perpendicular to the long axis (axial), and the other half were sectioned parallel to long axis (longitudinal). Differential staining, microradiography and histomorphometry were performed. Data were statistically analyzed by ANOVA (p=0.05) and Bonferroni/Dunn pair–wise comparisons (p=0.0083). Findings: Pull–out test: Empty 6 weeks group demonstrated the highest pull–out strength (3718N) compared to rhBMP–2/ACS 12 weeks (2330N, pde novoosteopenic bone as far as 8–10 mm away from the screw. Conclusions: rhBMP–2 did not significantly improve the biomechanical pull–out properties (stiffness, strength, and energy) of the titanium implant. 12 weeks rhBMP–/ACS specimens had improved biomechanical pull–out strength and stiffness compared to 6 weeks rhBMP–2/ACS specimens. rhBMP–2 application was associated with early transient bone resorption, de novo florid osteopenic bone, and statistically significant bone density differences at the 6 weeks period. These were replaced by remodeled bone at the 12 weeks time period

'Clinical Triad' findings in Klippel-feil patients

E-Poster - Congenital Deformity: no. 530It has been propagated that Klippel-Feil Syndrome (KFS) is associated with the clinical triad findings (CTF) of short neck, low posterior hairline, and limited range of motion. This study noted that CTFs are not consistently noted in KFS patients. KFS patients with extensive congenitally fused cervical segments were more likely to exhibit one of the components of CTF.postprin

Selection of fusion levels in adolescent idiopathic scoliosis (AIS) using the fulcrum bending radiograph prediction: verification based on pedicle screw strategy

E-Poster - Adolescent Idiopathic Scoliosis: no. 297Utilizing the fulcrum bending radiographic technique to assess curve flexibility to aid in the selection of fusion levels, a prospective radiographic study was performed to assess the safety and effectiveness of pedicle screw fixation with alternate level screw strategy (ALSS) for thoracic AIS. This study suggests that ALSS obtains greater deformity correction than hook and hybrid systems, and improves balance without compromising fusion levels.postprin