Advancing Prone-Transpsoas Spine Surgery: A Narrative Review and Evolution of Indications with Representative Cases.

The Prone Transpsoas (PTP) approach to lumbar spine surgery, emerging as an evolution of lateral lumbar interbody fusion (LLIF), offers significant advantages over traditional methods. PTP has demonstrated increased lumbar lordosis gains compared to LLIF, owing to the natural increase in lordosis afforded by prone positioning. Additionally, the prone position offers anatomical advantages, with shifts in the psoas muscle and lumbar plexus, reducing the likelihood of postoperative femoral plexopathy and moving critical peritoneal contents away from the approach. Furthermore, operative efficiency is a notable benefit of PTP. By eliminating the need for intraoperative position changes, PTP reduces surgical time, which in turn decreases the risk of complications and operative costs. Finally, its versatility extends to various lumbar pathologies, including degeneration, adjacent segment disease, and deformities. The growing body of evidence indicates that PTP is at least as safe as traditional approaches, with a potentially better complication profile. In this narrative review, we review the historical evolution of lateral interbody fusion, culminating in the prone transpsoas approach. We also describe several adjuncts of PTP, including robotics and radiation-reduction methods. Finally, we illustrate the versatility of PTP and its uses, ranging from 'simple' degenerative cases to complex deformity surgeries.

Risk of Injury to Retroperitoneal Structures in Prone and Lateral Decubitus Transpsoas Approaches to Lumbar Interbody Fusion: A Pilot Cadaveric Anatomical Study.

Introduction The retroperitoneal approach for lateral lumbar interbody fusion (LLIF) originally described an initial posterolateral fascial incision enabling finger dissection from behind the peritoneum and guidance of instruments through a second direct-lateral fascial incision. It has since become common for single direct-lateral incisional access to the retroperitoneum. This study attempted to quantify the distance of the peritoneum from posterior landmarks in the space, assess the risk of peritoneal violation in each access trajectory (i.e., posterolateral versus direct lateral retroperitoneal dissection), and determine whether there are differences based on patient position (prone versus lateral decubitus). Methods In three prone cadaveric torsos, Steinman pins were percutaneously placed mid-disc at each level L2-5 bilaterally (for a total of 18 prone approaches). Open dissections exposed the retroperitoneum including the quadratus lumborum and psoas muscles, maintaining the natural reflection of the peritoneum. Visual assessment qualified whether any pin violated any retroperitoneal structure. Distance from the anterior border of the quadratus lumborum to the posterior-most reflection of the peritoneum was measured. For comparison, three additional torsos were positioned in lateral decubitus, and the above steps were repeated, only unilaterally (for a total of nine lateral decubitus approaches). Results In prone, no pin violated the peritoneum; three (3/18 total approaches) violated the kidney, all at L2-3 (3/6 approaches at L2-3). In lateral decubitus, all three L2-3 pins violated the kidney (3/3 approaches at L2-3); five of the six remaining pins from L3-5 violated the peritoneum (totaling eight violations in the nine total approaches). The incidence of any violation was significantly greater in lateral decubitus vs. prone (8/9 vs. 3/18, p=0.0006). The structure at risk (kidney vs. peritoneum) was significantly associated with disc level (p=0.0041): all kidney violations occurred at L2-3 and all peritoneal violations occurred at L3-4 or L4-5. Distance from the quadratus lumborum to the posterior-most reflection of the peritoneum averaged 8.7 cm (range: 6-10) in prone, and 2.9 cm (range: 2.5-3.2) in lateral decubitus (p=0.0129). Conclusion A cadaveric study of retroperitoneal anatomy demonstrates that there is an increased distance from the quadratus lumborum to the peritoneum in prone versus lateral decubitus and that the trajectory of approach to the lumbar discs risks violation of the peritoneum more frequently when accessing directly laterally versus posterolaterally. In either approach, care should be taken to identify and release the peritoneal reflection to create a safe passage to the lumbar discs.

Complications of the Prone Transpsoas Lateral Lumbar Interbody Fusion for Degenerative Lumbar Spine Disease: A Multicenter Study.

BACKGROUND AND OBJECTIVES: The prone transpsoas (PTP) approach for lateral lumbar interbody fusion (LLIF) is a novel technique for degenerative lumbar spine disease. However, there is a paucity of information in the literature on the complications of this procedure, with all published data consisting of small samples. We aimed to report the intraoperative and postoperative complications of PTP in the largest study to date. METHODS: A retrospective electronic medical record review was conducted at 11 centers to identify consecutive patients who underwent LLIF through the PTP approach between January 1, 2021, and December 31, 2021. The following data were collected: intraoperative characteristics (operative time, estimated blood loss [EBL], intraoperative complications [anterior longitudinal ligament (ALL) rupture, cage subsidence, vascular and visceral injuries]), postoperative complications, and hospital stay. RESULTS: A total of 365 patients were included in the study. Among these patients, 2.2% had ALL rupture, 0.3% had cage subsidence, 0.3% had a vascular injury, 0.3% had a ureteric injury, and no other visceral injuries were reported. Mean operative time was 226.2 ± 147.9 minutes. Mean EBL was 138.4 ± 215.6 mL. Mean hospital stay was 2.7 ± 2.2 days. Postoperative complications included new sensory symptoms-8.2%, new lower extremity weakness-5.8%, wound infection-1.4%, cage subsidence-0.8%, psoas hematoma-0.5%, small bowel obstruction and ischemia-0.3%, and 90-day readmission-1.9%. CONCLUSION: In this multicenter case series, the PTP approach was well tolerated and associated with a satisfactory safety profile.

Comparison of segmental lordosis gain of prone transpsoas (PTP) vs. lateral lumbar interbody fusion.

INTRODUCTION: Lumbar interbody fusion is a standard method to treat certain degenerative conditions that are refractory to conservative treatments. LLIF reduces posterior muscle damage, can relieve neurological symptoms through indirect decompression, provides increased stability with its wider cages, and promotes more significant segmental lordosis than standard posterior techniques. However, the technique possesses its issues, such as unusual positioning, possible plexus-related symptoms, and median segmental lordosis correction. Trying to ease those issues, the idea of a prone transpsoas technique occurred. METHODS: Retrospective, single-centric, comparative, and non-randomized study. The authors paired patients receiving lateral lumbar interbody fusion (LLIF) or prone transpsoas (PTP) to evaluate the technique's impact on the segmental lordosis correction. A correlation test selected the covariates for the matching. p-Values inferior to 0.05 were deemed significant. RESULTS: Seventy-one patients were included in the analysis, 53 in the LLIF group and 18 in the PTP group. The significant covariates to the segmental lordosis correction were technique, preoperative segmental lordosis, cage position, and preoperative pelvic tilt. After the paring model, PTP showed significant segmental lordosis correction potential regarding the LLIF. CONCLUSION: The prone transpsoas approach can significantly enhance the correction of segmental lordosis proportionated to the traditional LLIF approach.

Lateral versus posterior approaches to treat degenerative lumbar pathologies-systematic review and meta-analysis of recent literature.

INTRODUCTION: The lateral lumbar interbody fusion arose as a revolutionary approach to treating several spinal pathologies because the techniques were able to promote indirect decompression and lordosis restoration through a minimally invasive approach allowing for reduced blood loss and early recovery for patients. However, it is still not clear how the technique compares to other established approaches for treating spinal degenerative diseases, such as TLIF, PLIF, and PLF. MATERIAL AND METHODS: This is a systematic review and meta-analysis of articles published in the last 10 years comparing lateral approaches to posterior techniques. The authors included articles that compared the LLIF technique to one or more posterior approaches, treating only degenerative pathologies, and containing at least one of the key outcomes of the study. Exclusion articles that were not original and the ones that the authors could not obtain the full text; also articles without the possibility to calculate the standard deviation or mean were excluded. For count variables, the odds ratio was used, and for continuous variables, the standard means difference (SMD) was used, and the choice between random or fixed-effects model was made depending on the presence or not of significant (p < 0.05) heterogeneity in the sample. RESULTS: Twenty-four articles were included in the quantitative review. As for the intra-/perioperative variables, the lateral approaches showed a significant reduction in blood loss (SMD-1.56, p < 0.001) and similar operative time (SMD = - 0.33, p = 0.24). Moreover, the use of the lateral approaches showed a tendency to lead to reduced hospitalization days (SMD = - 0.15, p = 0.09), with significantly reduced odds ratios of complications (0.53, p = 0.01). As for the clinical outcomes, both approaches showed similar improvement both at improvement as for the last follow-up value, either in ODI or in VAS-BP. Finally, when analyzing the changes in segmental lordosis and lumbar lordosis, the lateral technique promoted significantly higher correction in both outcomes (p < 0.05). CONCLUSION: Lateral approaches can promote significant radiological correction and similar clinical improvement while reducing surgical blood loss and postoperative complications.

Radiographic alignment outcomes after the single-position prone transpsoas approach: a multi-institutional retrospective review of 363 cases.

OBJECTIVE: The aim of this paper was to evaluate the changes in radiographic spinopelvic parameters in a large cohort of patients undergoing the prone transpsoas approach to the lumbar spine. METHODS: A multicenter retrospective observational cohort study was performed for all patients who underwent lateral lumber interbody fusion via the single-position prone transpsoas (PTP) approach. Spinopelvic parameters from preoperative and first upright postoperative radiographs were collected, including lumbar lordosis (LL), pelvic incidence (PI), and pelvic tilt (PT). Functional indices (visual analog scale score), and patient-reported outcomes (Oswestry Disability Index) were also recorded from pre- and postoperative appointments. RESULTS: Of the 363 patients who successfully underwent the procedure, LL after fusion was 50.0° compared with 45.6° preoperatively (p < 0.001). The pelvic incidence-lumbar lordosis mismatch (PI-LL) was 10.5° preoperatively versus 2.9° postoperatively (p < 0.001). PT did not significantly change (0.2° ± 10.7°, p > 0.05). CONCLUSIONS: The PTP approach allows significant gain in lordotic augmentation, which was associated with good functional results at follow-up.

Effects of 3D Airway Geometry on the Airflow of Adults with Cleft Lip and Palate and Obstructive Sleep Apnea: A Functional Imaging Study.

Objective Individuals with cleft lip and palate (CLP) are at a high risk of developing obstructive sleep apnea (OSA). Hypothetically, the severity of OSA might be associated with the morphology of the upper airway (UAW) and the characteristics of the airflow. Thus, the present study aimed to assess and compare, in adults with CLP and skeletal class-III discrepancy, with or without OSA, simulations of airflow resistance and pressure according to the geometrical characteristics of the UAW and cephalometric parameters. Materials and Methods According to the results of type-I polysomnography tests, the sample ( n = 21) was allocated in 2 groups: 1) without OSA (N-OSA; n = 6); and 2) with OSA (OSA; n = 15). Cephalometric measurements were performed on the cone-beam computed tomography (CBCT) scans of the groups. After three-dimensional (3D) reconstructions, the volume (V) and minimal cross-sectional area (mCSA) of the UAW were generated. Computational fluid dynamics (CFD) simulations were used to assess key airflow characteristics. The results were presented at a significance level of 5%. Results The UAW pressure values and airway resistance did not differ between the groups, but there was a tendency for more negative pressures (26%) and greater resistance (19%) in the OSA group. Volume and mCSA showed a moderate negative correlation with resistance and pressure. The more inferior the hyoid bone, the more negative the pressures generated on the pharyngeal walls. Conclusion The position of the hyoid bone and the geometry of the UAW (V and mCSA) exerted effects on the airway-airflow resistance and pressure. However, key airflow characteristics did not differ among subjects with CLP, were they affected or not by OSA.

Impact of the Preoperative Spinopelvic Parameters on the Segmental Lordosis Correction after One-level Lateral Lumbar Interbody Fusion.

Objectives The present study aimed to assess whether preoperative spinopelvic parameters can influence the gain of segmental lordosis after one level of lateral lumbar interbody fusion. Methods The following radiological parameters were measured in the X-rays: pelvic incidence, lumbar lordosis, pelvic tilt, L4S1 lordosis, index level segmental lordosis, intraoperative index segmental lordosis, pelvic mismatch (IP-LL), distal lordosis proportion, delta segmental lordosis, Pelvic Titlt (PT) > 20, actual sacral slope, and ideal sacral slope, and the correlation of these variables with the gain of segmental lordosis was investigated. Afterwards, an exploratory cluster analysis was performed to identify common characteristics between patients and segmental lordosis gain. Results The sample of the present study comprised 104 patients, of which 76% presented segmental lordosis gain. The most correlated parameters with the segmental lordosis gain were preoperative segmental lordosis (-0.50) and delta intraoperative lordosis (0.51). Moreover, patients in the high PI groups had a trend to gain more segmental lordosis ( p < 0.05) and a reduced risk of losing segmental lordosis (Odds 6.08). Conclusion Patients with low-medium PI profiles presented higher odds of loss of segmental lordosis. However, the preoperative spinopelvic parameters alone do not seem to play a significant role in the fate of segmental lordosis gain.

Impact of the Preoperative Spinopelvic Parameters on the Segmental Lordosis Correction after One-level Lateral Lumbar Interbody Fusion / Impacto dos parâmetros espinopélvicos pré-operatórios na correção de lordose segmentar após fusão intersomática lombar por via lateral de um nível

Abstract Objectives The present study aimed to assess whether preoperative spinopelvic parameters can influence the gain of segmental lordosis after one level of lateral lumbar interbody fusion. Methods The following radiological parameters were measured in the X-rays: pelvic incidence, lumbar lordosis, pelvic tilt, L4S1 lordosis, index level segmental lordosis, intraoperative index segmental lordosis, pelvic mismatch (IP-LL), distal lordosis proportion, delta segmental lordosis, Pelvic Titlt (PT) > 20, actual sacral slope, and ideal sacral slope, and the correlation of these variables with the gain of segmental lordosis was investigated. Afterwards, an exploratory cluster analysis was performed to identify common characteristics between patients and segmental lordosis gain. Results The sample of the present study comprised 104 patients, of which 76% presented segmental lordosis gain. The most correlated parameters with the segmental lordosis gain were preoperative segmental lordosis (−0.50) and delta intraoperative lordosis (0.51). Moreover, patients in the high PI groups had a trend to gain more segmental lordosis (p< 0.05) and a reduced risk of losing segmental lordosis (Odds 6.08). Conclusion Patients with low-medium PI profiles presented higher odds of loss of segmental lordosis. However, the preoperative spinopelvic parameters alone do not seem to play a significant role in the fate of segmental lordosis gain.

Resumo Objetivos O presente estudo teve como objetivo avaliar se os parâmetros espinopélvicos pré-operatórios podem influenciar o ganho da lordose segmental após fusão intersomática lombar por via lateral de um nível. Métodos Os seguintes parâmetros radiológicos foram medidos nos raios X: incidência pélvica, lordose lombar, versão pélvica, lordose L4S1, lordose segmental do nível operado, índice intraoperatório de lordose segmentar, mismatch pélvico (IP-LL), proporção de lordose distal, delta de lordose segmentar, PT > 20, inclinação sacral real e inclinação sacral ideal, e a correlação dessas variáveis com o ganho da lordose segmentar foi investigada. Posteriormente, foi realizada uma análise exploratória de cluster para identificar características comuns entre os pacientes e o ganho de lordose segmentar. Resultados O presente estudo contou com 144 pacientes, dos quais 76% apresentaram ganho de lordose segmentar. Os parâmetros mais correlacionados com o ganho de lordose segmentar foram lordose segmentar pré-operatória (−0,50) e delta intraoperatório de lordose (0,51). Além disso, os pacientes dos grupos de incidência pélvica (IP) alto tiveram tendência de ganho de lordose segmental maior (p< 0,05) e redução do risco de perda de lordose segmental (chances 6.08). Conclusão Pacientes com perfis de IP médios baixos apresentaram maiores chances de perda de lordose segmentar. No entanto, os parâmetros espinopélvicos pré-operatórios por si só não parecem desempenhar um papel significativo no destino do ganho da lordose segmentar.

Minimally invasive versus open surgery for degenerative lumbar pathologies:a systematic review and meta-analysis.

INTRODUCTION: With the increase in life expectancy and consequent aging of the population, degenerative lumbar spine diseases tend to increase its number exponentially. Several treatment options are available to treat degenerative spinal diseases, such as laminectomies, posterior fusions, and interbody fusions, depending on their locations, correction necessities, and surgeon philosophy. With the advance in technology and surgical knowledge, minimally invasive techniques (MIS) arose as a solution to reduce surgical morbidity, while maintaining the same benefits as the traditionally/open surgeries. Several studies investigated the possible advantages of MIS techniques against the traditional open procedures. However, those articles are usually focused only on one technique or on one pathology. METHODS: The electronic databases, including PubMed, Google Scholar, Ovid, and BVS, were systematically reviewed. Only original articles in English or Portuguese were added to the review, the revision was performed following the PRISMA guideline. RESULTS: Fifty-three studies were included in the meta-analysis. Of the studied outcomes the Length of Stay Odds of complications, Blood Loss, and Surgery costs presented significantly favored MIS approaches, while the Last FUP ODI score, and Surgery Time did not differ among the groups. CONCLUSION: Minimally invasive techniques are a remarkably interesting option to traditional open surgeries, as these procedures showed a significant reduction in blood loss, hospitalization time, complications, and surgical costs.

Single-position prone transpsoas fusion for the treatment of lumbar adjacent segment disease: early experience of twenty-four cases across three tertiary medical centers.

PURPOSE: Prone transpsoas fusion (PTP) is a minimally invasive technique that maximizes the benefit of lateral access interbody surgery and the prone positioning for surgically significant adjacent segment disease. The authors describe the feasibility, reproducibility and radiographic efficacy of PTP when performed for cases of lumbar ASD. METHODS: Adult patients undergoing PTP for treatment of lumbar ASD at three institutions were retrospectively enrolled. Demographic information was recorded, as was operative data such as adjacent segment levels, operative time, blood loss, laterality of approach, open versus percutaneous pedicle screw instrumentation and need for primary decompression. Radiographic measurements including segmental and global lumbar lordosis, pelvic incidence, pelvic tilt, sacral slope and sagittal vertical axis were recorded both pre- and immediately post-operatively. RESULTS: Twenty-four patients met criteria for inclusion. Average age was 60.4 ± 10.4 years and average BMI was 31.6 ± 5.0 kg/m2. Total operative time was 204.7 ± 83.3 min with blood loss of 187.9 ± 211 mL. Twenty-one patients had pedicle screw instrumentation exchanged percutaneously and 3 patients had open pedicle screw exchange. Two patients suffered pulmonary embolism that was treated medically with no long-term sequelae. One patient had transient lumbar radicular pain and all patients were discharged home with an average length of stay of 3.0 days (range 1-6). Radiographically, global lumbar lordosis improved by an average of 10.3 ± 9.0 degrees, segmental lordosis by 10.1 ± 13.3 degrees and sagittal vertical axis by 3.2 ± 3.2 cm. CONCLUSION: Single-position prone transpsoas lumbar interbody fusion is a clinically reproducible minimally invasive technique that can effectively treat lumbar adjacent segment disease.

Comparison of psoas morphology and lumbar lordosis in different postures / Comparação da morfologia do psoas e lordose lombar em diferentes posturas / Comparación de la morfología del psoas y la lordose lumbar en diferentes posturas

ABSTRACT Objective: To compare the interobserver reliability of measurements of psoas morphology and lumbar lordosis in different positions and to standardize the performance of magnetic resonance imaging in the prone and lateral positions. Methods: This is a cross-sectional study carried out with asymptomatic volunteers of both sexes, aged over 18 years, with no known pathological changes in the lumbar region. Magnetic resonance imaging of the lumbar spine was performed in the supine, right lateral decubitus and prone positions, obtaining images in T2-weighted sequences in the sagittal and axial planes. The distances were measured from the psoas to the vertebral plateau and from the psoas to the lumbar plexus. The exams were assessed by two independent, blinded orthopedists. Results: There was excellent agreement between the measurements of vertebral size (ICC=0.92), low agreement for plexus distance (ICC=0.63) and high agreement for the anterior margin (ICC=0.84). Conclusion: There was good reproducibility of 2 of the 3 measures proposed, suggesting that the technique in the lateral and prone positions is capable of generating quality images. Level of Evidence 3B; Prospective.

RESUMO Objetivo: Comparar a confiabilidade interobservador da mensuração da morfologia do psoas e lordose lombar nas diferentes posições e padronizar a realização do exame de ressonância magnética em posição prona e lateral. Métodos: Trata-se de um estudo transversal realizado com voluntários assintomáticos de ambos os sexos, maiores de 18 anos, sem alterações patológicas conhecidas na região lombar. Foi realizada ressonância magnética da coluna lombar na posição supina, decúbito lateral direito e prono, obtendo imagens nas sequências ponderadas em T2 nos planos sagital e axial. Foram medidas as distâncias do psoas até o platô vertebral e o plexo lombar. Os exames foram avaliados por dois ortopedistas independentes em caráter cego. Resultados: Houve ótima concordância entre as medições do tamanho da vértebra (ICC=0.92), baixa concordância para a distância do plexo (ICC = 0,63) e alta concordância para a margem anterior (ICC = 0,84). Conclusão: Houve boa reprodutibilidade das medidas propostas, sugerindo que a técnica em posição lateral e prona é capaz de gerar imagens de qualidade. Nível de Evidência 3B; Prospectivo.

RESUMEN Objetivo: Comparar la fiabilidad interobservador de la medición de la morfología del psoas y la lordosis lumbar en diferentes posiciones y estandarizar la realización de la resonancia magnética en decúbito prono y lateral. Métodos: Se trata de un estudio transversal realizado con voluntarios asintomáticos de ambos sexos, mayores de 18 años, sin alteraciones patológicas conocidas en la región lumbar. Se realizó la resonancia magnética de la columna lumbar en decúbito supino, decúbito lateral derecho y prono, obteniendo imágenes en las secuencias potenciadas en T2 en los planos sagital y axial. Se midieron las distancias del psoas a la meseta vertebral y al plexo lumbar. Los exámenes fueron evaluados a ciegas por dos ortopedistas independientes. Resultados: Hubo una excelente concordancia entre las mediciones del tamaño de la vértebra (ICC = 0,92), una baja concordancia para la distancia del plexo (ICC = 0,63) y una alta concordancia para el margen anterior (ICC = 0,84). Conclusión: Hubo buena reproducibilidad de las medidas propuestas, lo que sugiere que la técnica en decúbito lateral y prono es capaz de generar imágenes de calidad. Nivel de evidencia 3B; Prospectivo.

Impact of obesity on the clinical outcomes of spinal surgery by transpsoas lateral fusion / Impacto da obesidade sobre os desfechos clínicos da cirurgia da coluna por artrodese lateral via transpsoas / Impacto de la obesidad en los resultados clínicos de la cirugía de columna mediante fusión lateral transpsoas

ABSTRACT Introduction: Obesity is a global phenomenon that affects the quality of life of the population. In addition to being a factor that can lead to cases of degeneration in the spine, it can also influence the clinical outcomes of spine surgeries. However, with the development of minimally invasive techniques, the impact of obesity has become uncertain. Methods: A single-center, non-randomized, comparative, observational study, here clinical and surgical outcomes and postoperative complications were analyzed between obese and non-obese patients undergoing LLIF surgery. Results: There was no difference between surgical times and blood loss between the groups; the number of postoperative complications was similar. Both groups showed significant improvement in clinical parameters, but there was no difference between the amount of improvement between the obese and non-obese groups. Conclusion: The present study demonstrated that LLIF is a safe and effective technique regardless of the patient's degree of obesity. Level of Evidence III; Retrospective study.

RESUMO Introdução: A obesidade é um fenômeno global que possui diversos sobre a qualidade de vida da população. Além de ser um fator que pode levar a casos de degeneração na coluna, como também pode influenciar nos desfechos clínicos das cirurgias de coluna. No entanto, com o desenvolvimento de técnicas minimamente invasivas o impacto da obesidade se tornou incerto. Métodos: Estudo de centro único, não-randomizado, comparativo, observacional, onde foram analisados os desfechos clínicos, cirúrgicos e complicações pós-operatórias entre pacientes obesos e não-obesos submetidos a cirurgia de LLIF. Resultados: Não houve diferença entre os tempos cirúrgicos e perda sanguínea entre os grupos, ademais o número de complicações pós-operatórias foi similar entre os grupos. Ambos os grupos apresentaram melhora significativa dos parâmetros clínicos, porém não houve diferença entre a quantidade de melhora entre os grupos obeso e não-obeso. Conclusão: O presente estudo demonstrou que o LLIF é uma técnica segura e eficaz independentemente do grau de obesidade do paciente. Nível de evidência III; Estudo retrospectivo.

RESUMEN Introducción: La obesidad es un fenómeno mundial que afecta la calidad de vida de la población. Además de ser un factor que puede conducir a casos de degeneración en la columna, también puede influir en los resultados clínicos de las cirugías de columna. Sin embargo, con el desarrollo de técnicas mínimamente invasivas, el impacto de la obesidad se ha vuelto incierto. Métodos: Estudio observacional, comparativo, no aleatorizado, unicéntrico, donde se analizaron los resultados clínicos, quirúrgicos y las complicaciones postoperatorias entre pacientes obesos y no obesos sometidos a cirugía LLIF. Resultados: No hubo diferencia entre los tiempos quirúrgicos y la pérdida de sangre entre los grupos, además, el número de complicaciones postoperatorias fue similar entre los grupos. Ambos grupos mostraron una mejora significativa en los parámetros clínicos, pero no hubo diferencia entre la cantidad de mejora entre los grupos obesos y no obesos. Conclusión: El presente estudio demostró que la LLIF es una técnica segura y eficaz independientemente del grado de obesidad del paciente. Nivel de Evidencia III; Estudio retrospectivo.

Study of the diameter of the oblique corridor in lateral decubitus and dorsal decubitus: radiological study / Estudo do diâmetro do corredor oblíquo em decúbito lateral e decúbito dorsal: estudo radiológico / Estudio del diámetro del corredor oblicuo en decúbito lateral y dorsal: estudio radiológico

ABSTRACT Introduction: Degenerative intervertebral disc disease and its impact on quality of life when associated with sagittal misalignmentis a current topic in the literature. The technique known as OLIF derives from the need to use anterior cage stop romote stabilization of the affected segment, indirect decompression, restoration of segmental lordosis, and sagittal balance. Methods: Single-center, non-randomized, comparative, observational study. The following variables were measured using magnetic resonance imaging of the lumbar spine in dorsal and lateral decubitus, establishing a comparison between the size of the OLIF corridor in the L3L4 and L4L5 segments, as well as a comparison of corridor size between the different positions. Results: There was no difference incorridor size in the comparison between decubitus. However, when the L3L4 and L4L5 levels were compared, there was a significant difference in the size of the corridor in both the lateral and dorsal positions. Conclusion: The present study did not show any difference between the size of the OLIF corridor in L3L4 and L4L5 in the different decubitus, suggesting that thee valuation of the corridor in convention al magnetic resonance images appearstobe safe andreflects the actual size when positio ned for performing the OLIF technique. Level of evidence III; Retrospective study.

RESUMO Introdução: A doença degenerativa do disco intervertebral e seu impacto sobre a qualidade de vida quando está associada a desalinhamento sagital é tema atual na literatura. A técnica conhecida como OLIF deriva da necessidade de uso de cages anteriores para promover estabilização do segmento afetado, descompressão indireta, restauração da lordose segmentar e equilíbrio sagital. Métodos: Estudo de centro único, não randomizado, comparativo, observacional. Foram medidas as seguintes variáveis por ressonância magnética de coluna lombar em decúbito dorsal e lateral, estabelecendo comparação entre o tamanho do corredor OLIF nos segmentos L3-L4 e L4-L5, assim como comparação entre o tamanho do corredor entre as diferentes posições. Resultados: Não houve diferença entre o tamanho do corredor na comparação entre os decúbitos. Entretanto, ao comparar os níveis L3-L4 e L4-L5 houve diferença significativa no tamanho do corredor, tanto na posição lateral quanto na posição dorsal. Conclusões: O presente estudo não demonstrou diferença detamanho do corredor OLIF em L3-L4 e L4-L5 em diferentes decúbitos, sugerindo que a avaliação do corredor em ressonância magnética convencional parece ser segura e reflete o tamanho real quando posicionado para execução da técnica OLIF. Nível de evidência III; Estudo retrospectivo.

RESUMEN Introducción: La enfermedad degenerativa del disco intervertebral y su impacto en lacalidad de vida cuando se asocia a una desalineación sagital es un tema actualenla literatura. La técnica conocida como OLIF deriva de la necesidad de utilizar cages anteriores para favorecer la estabilización del segmento afectado, la descompresión indirecta, la restauración de la lordosis segmentaria y el equilibrio sagital. Métodos: Estudio observacional comparativo unicéntrico, no aleatorizado. Se midieron las siguientes variables mediante resonancia magnética de la columna lumbar endecúbito dorsal y lateral, estableciendo la comparación entre el tamaño del corredor OLIF en los segmentos L3L4 y L4L5, así como la comparación entre el tamaño del corredor entre las diferentes posiciones. Resultados: No hubo diferencia entre el tamaño del corredor en la comparación entre decúbitos. Sin embargo, al comparar los niveles L3-L4 y L4-L5, hubo una diferencia significativa en el tamaño del corredor tanto en posición lateral como dorsal. Conclusiones: El presente estudio no mostró diferencias en el tamaño del corredor OLIF en L3-L4 y L4-L5, en diferentes posiciones de decúbito, lo que sugiere que la evaluación del corredor en la resonancia magnética convenciona lparece ser segura y refleja el tamaño real cuando se posiciona para realizar la técnica OLIF. Nivel de evidencia III; Estudio retrospectivo

The Effect of Patient Position on Psoas Morphology and in Lumbar Lordosis.

INTRODUCTION: Among the interbody fusions, lateral lumbar interbody fusion allows access to the lumbar spine through the major psoas muscle, which offers several advantages to the spine surgeon. However, some of its drawbacks cause surgeons to avoid using it as a daily practice. Therefore, to address some of these challenges, we propose the prone transpsoas technique, differing mainly from the traditional technique on patient position-moving from lateral to prone decubitus, theoretically enhancing the lordosis and impacting the psoas morphology. METHODS: Twenty-four consecutive patients were invited to have magnetic resonance imaging examinations in 3 different positions (prone, dorsal, lateral). Two observers measured the following parameters: vertebral body size, psoas diameter, psoas anterior border distance, plexus distance, total lumbar lordosis, distal lumbar lordosis, and proximal lumbar lordosis. Values of P < 0.05 were deemed significant. RESULTS: The prone position yielded a significant increase in the lumbar lordosis, both in L1-S1 (57° vs. 46.5°) and proximal lordosis (40.4° vs. 36.9°) compared with the lateral position. Regarding the morphologic aspects, patients in the prone position presented lesser psoas muscles forward shift, but no difference was noted in the plexus position neither for L3-L4 nor L4-L5. CONCLUSIONS: The prone position resulted in a significantly increased lumbar lordosis, both distal and proximal, which may enable the spine surgeon to achieve significant sagittal restoration just by positioning. The prone position also produced a posterior retraction of the psoas muscle. However, it did not significantly affect the position of the plexus concerning the vertebral body.

Indirect decompression by lateral fusion: analysis of sagital alignment / Descompressão indireta por fusão lateral: análise do alinhamento sagital / Descompresión indirecta por fusión lateral: análisis de la alineación sagital

ABSTRACT Objective: To verify the effectiveness of indirect decompression after lateral access fusion in patients with high pelvic incidence. Methods: A retrospective, non-comparative, non-randomized analysis of 22 patients with high pelvic incidence who underwent lateral access fusion, 11 of whom were male and 11 female, with a mean age of 63 years (52-74), was conducted. Magnetic resonance exams were performed within one year after surgery. The cross-sectional area of the thecal sac, anterior and posterior disc heights, and bilateral foramen heights, measured pre- and postoperatively in axial and sagittal magnetic resonance images, were analyzed. The sagittal alignment parameters were measured using simple radiographs. The clinical results were evaluated using the ODI and VAS (back and lower limbs) questionnaires. Results: In all cases, the technique was performed successfully without neural complications. The mean cross-sectional area increased from 126.5 mm preoperatively to 174.3 mm postoperatively. The mean anterior disc height increased from 9.4 mm preoperatively to 12.8 mm postoperatively, while the posterior disc height increased from 6.3 mm preoperatively to 8.1 mm postoperatively. The mean height of the right foramen increased from 157.3 mm in the preoperative period to 171.2 mm in the postoperative period and that of the left foramen increased from 139.3 mm in the preoperative to 158.9 mm in the postoperative. Conclusions: This technique is capable of correcting misalignment in spinal deformity, achieving fusion and promoting the decompression of neural elements. Level of evidence III; Retrospective study.

RESUMO Objetivo: Verificar a eficácia da descompressão indireta depois de fusão por acesso lateral em pacientes com alta incidência pélvica. Métodos: Análise retrospectiva, não comparativa, não randomizada de 22 pacientes com alta incidência pélvica submetidos à fusão por acesso lateral; 11 do sexo masculino e 11 do sexo feminino, com média de idade de 63 anos (52 a 74). Os exames de ressonância magnética foram realizados até um ano depois da cirurgia. Foram analisadas: área da seção transversal do saco tecal, altura discal anterior e posterior, altura dos forames bilaterais, medidas no pré e pós-operatório em imagens de ressonância magnética axial e sagital. Os parâmetros do alinhamento sagital foram medidos a partir de radiografia simples. Os resultados clínicos foram avaliados com os questionários ODI e EVA (costas e membros inferiores). Resultados: Em todos os casos, a técnica foi realizada com sucesso, sem complicações neurais. A área da secção transversal média aumentou de 126,5 mm no pré-operatório para 174,3 mm no pós-operatório. A média da altura anterior do disco aumentou de 9,4 mm no pré-operatório para 12,8 mm no pós-operatório, enquanto a altura posterior do disco aumentou de 6,3 mm no pré-operatório para 8,1 mm no pós-operatório. A média da altura do forame direito aumentou de 157,3 mm no pré-operatório para 171,2 mm no pós-operatório e a do forame esquerdo aumentou de 139,3 mm no pré-operatório para 158,9 mm no pós-operatório. Conclusões: Essa técnica é capaz de corrigir o desalinhamento na deformidade da coluna vertebral, alcançando a fusão e promovendo a descompressão dos elementos neurais. Nível de evidência III; Estudo Retrospectivo.

RESUMEN Objetivo: Verificar la eficacia de la descompresión indirecta después de fusión por acceso lateral en pacientes con alta incidencia pélvica. Métodos: Análisis retrospectivo, no comparativo, no aleatorizado de 22 pacientes con alta incidencia pélvica sometidos a fusión por acceso lateral; 11 del sexo masculino y 11 del sexo femenino, con promedio de edad de 63 años (52 a 74). Los exámenes de resonancia magnética fueron realizados hasta un año después de la cirugía. Fueron analizadas: área de la sección transversal del saco dural, altura discal anterior y posterior, altura de los for ámenes bilaterales, medidas en el pre y posoperatorio en imágenes de resonancia magnética axial y sagital. Los parámetros de la alineación sagital fueron medidos a partir de una radiografía simple. Los resultados clínicos fueron evaluados con los cuestionarios ODI y EVA (espalda y miembros inferiores). Resultados: En todos los casos, la técnica fue realizada con éxito, sin complicaciones neurales. El área de la sección transversal promedio aumentó de 126,5 mm en el preoperatorio para 174,3 mm en el postoperatorio. El promedio de altura anterior del disco aumentó de 9,4 mm en el preoperatorio para 12,8 mm en el postoperatorio, mientras que la altura posterior del disco aumentó de 6,3 mm en el preoperatorio para 8,1 mm en el postoperatorio. El promedio de altura del foramen derecho aumentó de 157,3 mm en el preoperatorio para 171,2 mm en el postoperatorio y la del foramen izquierdo aumentó de 139,3 mm en el preoperatorio para 158,9 mm en el postoperatorio. Conclusiones: Esta técnica es capaz de corregir la desalineación en la deformidad de la columna vertebral, alcanzando la fusión y promoviendo la descompresión de los elementos neurales. Nivel de evidencia III; Estudio retrospectivo.

Single-Position Prone Transpsoas Lateral Interbody Fusion Including L4L5: Early Postoperative Outcomes.

BACKGROUND: The lateral lumbar interbody fusion (LLIF) was a revolutionary approach devised by Luiz Pimenta that allowed the surgeon to access the lumbar spine through the major psoas muscle. Although the traditional LLIF had enabled enormous advances, the technique has its drawbacks. A new concept to perform the traditional LLIF has been proposed, with the patient being prone to decubitus with slightly extended legs. Our study aims to analyze the early outcomes of patients who had undergone the prone transpsoas (PTP) for degenerative spine pathologies including the L4/5 level. METHODS: This study was multicentric, retrospective, nonrandomized, noncomparative, and observational. Only participants who received PTP in L4/5, with no more than 3 levels of intersomatics and fixation no further than S1, were included. The primary outcomes were the onset of new neurologic deficits and postoperative complications. Also, surgery details, such as blood loss and surgery duration, were measured. Neurologic deficits were accessed at the postoperative visit, which ranged from 7 to 14 days after surgery. RESULTS: Twenty-seven patients fulfilled the inclusion and exclusion criteria, with the majority receiving PTP only in L4/5 (66.6%). The mean surgery time was 182, with 29 minutes of mean transpsoas time. Of the patients, only 1 presented the onset of a motor deficit, while 3 patients presented a new sensory deficit. Five complications occurred, none intraoperative and 5 postoperative, with only 1 directly correlated with the access. CONCLUSIONS: The prone transpsoas is safe and feasible for approaching the L4/5 disk, presenting with a low rate of complication and new-onset neurologic deficits.

Three-dimensional tomographic assessment of the upper airway using 2 different imaging software programs: A comparison study.

INTRODUCTION: Several imaging software programs with different tools are available for upper airway (UAW) analysis by means of cone beam computed tomography. Because of this wide variability, this study aimed to compare the reproducibility of two of the most used software programs on UAW segmentation, that is, Dolphin Imaging (Dolphin Imaging and Management Solutions, Chatsworth, Calif) and Mimics Research (Materialise, Leuven, Belgium). METHODS: The sample consisted of 50 scans of adult subjects with Class III malocclusion; pharyngeal volume and minimal cross-sectional area (mCSA) were assessed twice by 2 experienced evaluators using both software programs. Intra- and intersoftware and/or evaluator agreement were calculated using the intraclass correlation coefficient (ICC). Bland-Altman analysis was used to visualize the intersoftware and interevaluator agreement. RESULTS: Using Mimics Research and Dolphin Imaging, the respective mean values of volume (cm3) were 27.1 ± 8.4 and 24.7 ± 8.1 (P < 0.05) and of mCSA (mm2) were 167.8 ± 95.5 and 176.5 ± 102.3 (P < 0.05). Although differences between software packages were observed on both the analyzed variables, the results showed a high intersoftware agreement, with ICC of 0.87 (volume) and 0.97 (mCSA) and mean bias of 24.6 (volume) and -8.8 (mCSA). A high intrasoftware agreement was also observed, with values varying from 0.83 to 0.99. Excellent intra- and interevaluator agreement was also obtained, with ICC values from 0.93 to 0.99. CONCLUSIONS: Dolphin Imaging and Mimics Research individually provide highly reproducible results, with clinically acceptable agreement between them for UAW segmentation, providing consistent values for volume and mCSA.

Initial multi-centre clinical experience with prone transpsoas lateral interbody fusion: Feasibility, perioperative outcomes, and lessons learned.

BACKGROUND: Lateral interbody fusion (LIF) is traditionally performed with the patient in lateral decubitus, requiring repositioning to prone for adjunctive posterior procedures, or modifying traditional posterior techniques to be done while positioned lateral. The benefits of lateral anterior column access may be achievable with the patient prone, allowing for concomitant posterior techniques in a more familiar single-position setting. METHODS: Prone transpsoas (PTP) access was outlined and vetted by a group of LIF-experienced spine surgeons. Early clinical experience included prospectively capturing procedural details and perioperative outcomes across a multi-centre cohort of clinicians to assess feasibility and to identify efficiencies and/or challenges. RESULTS: Perioperative data was prospectively collected from 120 consecutive cases (176 levels) from 22 surgeons. Lateral exposure was achieved in an average 18 min/level, guided by triggered EMG; and retraction time averaged 25 min/level, with continued plexus monitoring via saphenous SSEP. Fixation was via percutaneous pedicle screws (65%), open pedicle screws (24%), other (11%). No re-positioning was required. Concomitant procedures facilitated by prone position included direct decompression (37%), treatment at L5-S1 (18%), posterior instrumentation revision (7%), and osteotomy/bony releases (9%). PTP procedure time, blood loss, and length of stay were consistent with established LIF experience. Challenges included patient movement with lateral instrument forces, retractor sag, stability of access relative to the patient, and surgeon ergonomics of the working channel. These challenges were overcome later in the experience through development of a specialized positioner and retractor system specific to this approach and a prescribed workflow developed by consensus of the surgeons. CONCLUSION: Initial multi-centre clinical experience suggests that PTP is not only feasible but creates efficiencies by allowing for single-position surgery maximizing both anterior and posterior column access and corrective techniques, with perioperative outcomes consistent with lateral decubitus experience. Learnings included the need for development of procedure-specific technologies and technique refinement.

Reduced pharyngeal dimensions and obstructive sleep apnea in adults with cleft lip/palate and Class III malocclusion.

Objective: To three-dimensionally evaluate the upper airway of individuals with cleft lip and palate (CLP) and Class III malocclusion and the occurrence of obstructive sleep apnea (OSA).Methods: Twenty-one CLP individuals with Class III malocclusion, 20-29 years of age, who underwent computed tomography for orthognathic surgery planning, were prospectively evaluated. All participants underwent polysomnography, and the apnea-hypopnea index ≥ 5 events/hour was considered indicative of OSA. The total upper airway and its subdivisions volumes, as well as the minimum pharyngeal cross-sectional area (CSA), were assessed using Mimics software.Results: Among the 21 individuals analyzed, 6 (29%) presented with OSA. The total upper airway and the oropharynx mean volumes were significantly decreased in subjects with OSA when compared to individuals without OSA. Mean CSA was not statistically different between groups.Conclusion: CLP individuals with Class III malocclusion and OSA have an upper airway significantly smaller than individuals without OSA.