Evaluation of the contact surface between vertebral endplate and 3D printed patient-specific cage vs commercial cage.

Biomechanical study. To evaluate the performance of the contact surface for 3D printed patient-specific cages using CT-scan 3D endplate reconstructions in comparison to the contact surface of commercial cages. Previous strategies to improve the surface of contact between the device and the endplate have been employed to attenuate the risk of cage subsidence. Patient-specific cages have been used to help, but only finite-element studies have evaluated the effectiveness of this approach. There is a possible mismatch between the CT-scan endplate image used to generate the cage and the real bony endplate anatomy that could limit the performance of the cages. A cadaveric model is used to investigate the possible mismatch between 3D printed patient-specific cages and the endplate and compare them to commercially available cages (Medtronic Fuse and Capstone). Contact area and contact stress were used as outcomes. When PS cage was compared to the Capstone cage, the mean contact area obtained was 100 ± 23.6 mm2 and 57.5 ± 13.7 mm2, respectively (p < 0.001). When compared to the Fuse cage, the mean contact area was 104.8 ± 39.6 mm2 and 55.2 ± 35.1 mm2, respectively(p < 0.001). Patient-specific cages improve the contact area between the implant and the endplate surface, reducing the contact stress and the risk of implant subsidence during LIF surgeries.

Anatomical Risk Factors for Anterior Cruciate Ligament Injury Are Not Important As Patellar Instability Risk Factors in Patients with Acute Knee Injury.

To compare in magnetic resonance imaging the anatomical risk factors for anterior cruciate ligament (ACL) injury and patellar dislocation among patients who suffered acute knee injury, 105 patients with acute knee injury resulting in 38 patellar dislocations (patella group), 35 ACL injuries (ACL group), and 32 meniscus or medial collateral ligament injuries (control group) were included. These groups were compared for risk factors for patellar dislocation (patellar height, trochlear dysplasia, and quadriceps angle of action) and for ACL injury (intercondylar width, posterior inclination of tibial plateaus, and depth of the medial plateau). Univariate analysis found statistically significant differences (p < 0.05) between the patella and ACL groups in patellar height (Caton-Deschamps [CD] 1.23 vs. 1.07), trochlear facet asymmetry (55 vs. 68%), PTTG (13.08 vs. 8.01 mm), and the patellar tip and trochlear groove (PTTG) angle (29.5 vs. 13.71 degrees). The patella group also differed from control in medial plateau inclination (4.8 vs. 1.87 degrees), patellar height (CD 1.23 vs 1.08), trochlear facet asymmetry (55 vs. 69%), lateral trochlear inclination (17.11 vs. 20.65 degrees), trochlear depth (4.1 vs. 6.05 mm), PTTG (13.08 vs. 9.85 mm), and the PTTG angle (29.5 vs. 17.88 degrees). The ACL and control groups were similar in all measures. Multivariate analysis found the following significant determinants between the Patella and Control groups: patellar height (CD index, odds ratio [OR]: 80.13, p = 0.015), trochlear anatomy (asymmetry of facets M/L, OR: 1.06, p = 0.031) and quadriceps action angle (PTTG angle, OR: 1.09, p = 0.016); between the ACL and control groups: PTTG angle (OR: 0.936, p = 0.04) and female gender (OR: 3.876, p = 0.032); and between the patella and ACL groups, the CD index (OR: 67.62, p = 0.026), asymmetry of the M/L facets (OR: 1.07, p = 0.011) and PTTG angle (OR: 1.16, p < 0.001). In conclusion, in patients with acute knee injury, the anatomical factors patellar height, trochlear dysplasia, and quadriceps angle of action were related to the occurrence of patellar dislocation. None of the anatomical factors studied was related to the occurrence of anterior cruciate ligament injury.

Geometric and Volumetric Relationship Between Human Lumbar Vertebra and CT-based Models.

RATIONALE AND OBJECTIVES: Crucial to the process of three-dimensional (3D) printing is the knowledge of how the actual structure or organ relates dimensionally to its corresponding medical image. This study will examine the differences between human lumbar vertebrae, 3D scans of these bones, 3D models based on computed tomographic (CT) scans, and 3D-printed models. MATERIALS AND METHODS: CT scans were obtained for six human lumbar spines. The bones were cleaned, and 3D scanned. 3D mesh models were created from the CT data, and then 3D printed. Four models were analyzed: anatomic bones, 3D-scanned models, CT-models, and 3D-printed models. Manual measurements were performed for all model types, and segmentation metric comparisons were performed comparing the 3D-scanned models to the CT-models. RESULTS: There was no statistical difference between manual measurements when comparing each parameter of all model types, except for vertebral width (p = 0.044). There was no statistical difference when comparing the average of all measurements between all model types (p = 0.247). The mean Hausdorff distance was 0.99 mm (SD 0.55 mm) when comparing 3D-scanned model to CT-model. The mean Dice coefficient was 0.90 (SD 0.07) when comparing 3D-scanned model to CT-model. The mean volume for 3D-scanned model and CT-model were 41.6 ml and 45.9 ml (p < 0.001), respectively. CONCLUSION: This study clarifies the geometric and volumetric relationship between human lumbar vertebra and CT-based vertebral models. Segmentation metrics reveal a 1 mm difference between examined bones (using the 3D-scanned bone as a surrogate), and the CT measurements. This is confirmed by a volumetric difference of 4.3 ml, between the larger CT-based model and the smaller bone.

Comparative tomographic study of the iliac screw and the S2-alar-iliac screw in children.

OBJECTIVES: The recent advancements in spine fixation aid in the treatment of complex spinal pathologies. Both the iliac screw (IS) and the S2-alar-iliac (S2AI) screw provide adequate stability in the fixation of complex lumbosacral spine pathologies, leading to a significant increased rate of using these techniques in the daily practice of the spine surgeons. This study aims to analyze, describe, and compare the insertion and positioning parameters of the S2AI screw and IS techniques in children without spinal deformities. METHODS: An observational retrospective study was conducted at a university hospital in 2018, with 25 computed tomography (CT) images selected continuously. Mann-Whitney-Shapiro-Wilk tests were performed. The reliability of the data was assessed using the intraclass correlation. The data were stratified by age group only for Pearson's correlation analysis. RESULTS: The mean age was 11.7 years (4.5 SD). The mean IS length was 106.63 mm (4.59 SD). The mean length of the S2AI screw was 104.13 mm (4.22 SD). The mean skin distance from the IS entry point was 28.13 mm (4.27 SD) and that for the S2AI screw was 39.96 mm (4.54 SD). CONCLUSIONS: Through CT, the S2AI screw trajectory was observed to have a greater bone thickness and skin distance than the IS. There was a linear correlation between age and screw length for both techniques. A similar relationship was observed between skin distance and age for the S2AI screw technique. In children, the S2AI screw technique presents advantages such as greater cutaneous coverage and implant thickness than the IS technique.

ROLE OF DIFFERENT HORMONES IN THE PATHOGENESIS AND SEVERITY OF ADOLESCENT IDIOPATHIC SCOLIOSIS.

OBJECTIVE: To evaluate the hormonal profile of patients with adolescent idiopathic scoliosis (AIS) and its relationship to the severity of the curvature and quality of life . METHOD: Patients with scoliosis (Cobb angle above 10°), of both genders, diagnosed after 10 years of age were included, excluding those who presented other condition that could lead to scoliosis. Serum levels of 25-hydroxyvitamin D (25-OHD), cortisol and gastrin were correlated with Cobb angle and quality of life, measured by the SRS-30 questionnaire . RESULTS: The levels of 25-OHD decreased in 97% of patients. There was an inverse relationship between gastrin levels and quality of life (p = 0.016). Moreover, there was an inverse correlation between the value of Cobb angle and quality of life (p = 0.036). There were no changes in cortisol levels. There was no correlation between Cobb angle and any of the hormones measured . CONCLUSION: The patients had levels of 25-OHD diminished, strengthening the hypothesis of its involvement in the development of AIS. This study also suggests that increased gastrin levels may be associated with a worse quality of life in patients with AIS. Level of Evidence II, Diagnostic Study.

OBJETIVO: Avaliar o perfil hormonal dos pacientes com escoliose idiopática do adolescente (EIA) e sua relação com a gravidade da curvatura e qualidade de vida. MÉTODO: Foram incluídos pacientes com escoliose (ângulo de Cobb acima de 10°), de ambos os sexos, diagnosticados após 10 anos de idade e foram excluídos aqueles que apresentassem outra condição que pudesse acarretar em escoliose. Os valores séricos da 25-hidroxivitamina D (25-OHD), cortisol e gastrina foram correlacionados com o ângulo de Cobb e a qualidade de vida, mensurada através do questionário SRS-30. RESULTADOS: Os níveos de 25-OHD estavam reduzidos em 97% dos pacientes. Observou-se uma relação inversa entre níveis de gastrina e a qualidade de vida (p=0,016). Ademais, constatou-se correlação inversa entre o valor do ângulo de Cobb e a qualidade de vida (p=0,036). Não foram observadas alterações nos níveis de cortisol. Não houve correlação do ângulo de Cobb com o nível de nenhum dos hormônios dosados. CONCLUSÃO: Os pacientes apresentaram níveis de 25-OHD diminuídos, fortalecendo a hipótese da sua implicação no desenvolvimento da EIA. O presente estudo também sugere que o aumento dos níveis de gastrina possa estar relacionado com pior qualidade de vida nos pacientes com EIA. Nível de Evidência II, Estudo Diagnóstico.

Comparative tomographic study of the iliac screw and the S2-alar-iliac screw in children

OBJECTIVES: The recent advancements in spine fixation aid in the treatment of complex spinal pathologies. Both the iliac screw (IS) and the S2-alar-iliac (S2AI) screw provide adequate stability in the fixation of complex lumbosacral spine pathologies, leading to a significant increased rate of using these techniques in the daily practice of the spine surgeons. This study aims to analyze, describe, and compare the insertion and positioning parameters of the S2AI screw and IS techniques in children without spinal deformities. METHODS: An observational retrospective study was conducted at a university hospital in 2018, with 25 computed tomography (CT) images selected continuously. Mann-Whitney-Shapiro-Wilk tests were performed. The reliability of the data was assessed using the intraclass correlation. The data were stratified by age group only for Pearson's correlation analysis. RESULTS: The mean age was 11.7 years (4.5 SD). The mean IS length was 106.63 mm (4.59 SD). The mean length of the S2AI screw was 104.13 mm (4.22 SD). The mean skin distance from the IS entry point was 28.13 mm (4.27 SD) and that for the S2AI screw was 39.96 mm (4.54 SD). CONCLUSIONS: Through CT, the S2AI screw trajectory was observed to have a greater bone thickness and skin distance than the IS. There was a linear correlation between age and screw length for both techniques. A similar relationship was observed between skin distance and age for the S2AI screw technique. In children, the S2AI screw technique presents advantages such as greater cutaneous coverage and implant thickness than the IS technique.

ROLE OF DIFFERENT HORMONES IN THE PATHOGENESIS AND SEVERITY OF ADOLESCENT IDIOPATHIC SCOLIOSIS / PAPEL DE DIFERENTES HORMÔNIOS NA PATOGÊNESE E GRAVIDADE DA ESCOLIOSE IDIOPÁTICA DO ADOLESCENTE

ABSTRACT Objective: To evaluate the hormonal profile of patients with adolescent idiopathic scoliosis (AIS) and its relationship to the severity of the curvature and quality of life . Method: Patients with scoliosis (Cobb angle above 10°), of both genders, diagnosed after 10 years of age were included, excluding those who presented other condition that could lead to scoliosis. Serum levels of 25-hydroxyvitamin D (25-OHD), cortisol and gastrin were correlated with Cobb angle and quality of life, measured by the SRS-30 questionnaire . Results: The levels of 25-OHD decreased in 97% of patients. There was an inverse relationship between gastrin levels and quality of life (p = 0.016). Moreover, there was an inverse correlation between the value of Cobb angle and quality of life (p = 0.036). There were no changes in cortisol levels. There was no correlation between Cobb angle and any of the hormones measured . Conclusion: The patients had levels of 25-OHD diminished, strengthening the hypothesis of its involvement in the development of AIS. This study also suggests that increased gastrin levels may be associated with a worse quality of life in patients with AIS. Level of Evidence II, Diagnostic Study.

RESUMO Objetivo: Avaliar o perfil hormonal dos pacientes com escoliose idiopática do adolescente (EIA) e sua relação com a gravidade da curvatura e qualidade de vida. Método: Foram incluídos pacientes com escoliose (ângulo de Cobb acima de 10°), de ambos os sexos, diagnosticados após 10 anos de idade e foram excluídos aqueles que apresentassem outra condição que pudesse acarretar em escoliose. Os valores séricos da 25-hidroxivitamina D (25-OHD), cortisol e gastrina foram correlacionados com o ângulo de Cobb e a qualidade de vida, mensurada através do questionário SRS-30. Resultados: Os níveos de 25-OHD estavam reduzidos em 97% dos pacientes. Observou-se uma relação inversa entre níveis de gastrina e a qualidade de vida (p=0,016). Ademais, constatou-se correlação inversa entre o valor do ângulo de Cobb e a qualidade de vida (p=0,036). Não foram observadas alterações nos níveis de cortisol. Não houve correlação do ângulo de Cobb com o nível de nenhum dos hormônios dosados. Conclusão: Os pacientes apresentaram níveis de 25-OHD diminuídos, fortalecendo a hipótese da sua implicação no desenvolvimento da EIA. O presente estudo também sugere que o aumento dos níveis de gastrina possa estar relacionado com pior qualidade de vida nos pacientes com EIA. Nível de Evidência II, Estudo Diagnóstico.