L4-L5 anatomy classification system for lateral lumbar interbody fusion.

Lateral lumbar interbody fusion (LLIF), developed by Dr. Luiz Pimenta in 2006, allows access to the spinal column through the psoas major muscle. The technique has many advantages, such as reduced bone and muscular tissue damage, indirect decompression, larger implants, and lordosis correction capabilities. However, this technique also has drawbacks, with the most notorious being the risk of spinal pathologies due to indirect injury of the lumbar plexus, but with low rates of persistent injuries. Therefore, several groups have proposed classifications to help identify patients at a greater risk of presenting with neurological deficits. The present work proposes a classification system that relies on simple observation of easily identifiable key structures to guide lateral L4-L5 LLIF decision-making. Patients aged > 18 years who underwent preoperative magnetic resonance imaging (MRI) between 2022 and 2023 were included until 50 high-quality images were acquired. And excluded as follow Anatomical changes in the vertebral body or major psoas muscles prevent the identification of key structures or poor-quality MRIs. Each anatomy was classified as type I, type II, or type III according to the consensus among the three observers. Fifty anatomical sites were included in this study. 70% of the L4-L5 anatomy were type I, 18% were type II, and 12% were type III. None of the type 3 L4-L5 anatomies were approached using a lateral technique. The proposed classification is an easy and simple method for evaluating the feasibility of a lateral approach to-L4-L5.

Experimental Analysis of Stress Shielding Effects in Screw Spacers Placed in Porcine Spinal Tissue.

Bone cortical tissues reorganize and remodel in response to tensile forces acting on them, while compressive forces cause atrophy. However, implants support most of the payload. Bones do not regenerate, and stress shielding occurs. The aim is to analyze the biomechanical behavior of a lumbar cage to study the implant's stress shielding. The ASTM E-9 standard was used with the necessary adjustments to perform compression tests on lumbar and thoracic porcine spinal vertebrae. Twelve cases were analyzed: six with the metal prosthesis and six with the PEEK implant. A mathematical model based on the Hertz contact theory is proposed to assess the stress shielding for endoprosthesis used in spine pathologies. The lumbar spacer (screw) helps to reduce the stress shielding effect due to the ACME thread. The best interspinous spacer is the PEEK screw. It does not embed in bone. The deformation capability increases by 11.5% and supports 78.6 kg more than a system without any interspinous spacer.

Survey of major complications after prone transpsoas surgery: an analysis of early adopters' practice.

INTRODUCTION: The prone transpsoas technique (PTP) is a modification of the traditional lateral lumbar interbody fusion approach, which was first published in the literature in 2020. The technique provides several advantages, such as lordosis correction and redistribution, single-position surgery framework, and ease of performing posterior techniques when needed. However, the prone position also leads to the movement of some retroperitoneal, vascular, and neurological structures, which could impact the complication profile. Therefore, this study aimed to investigate the occurrence of major complications in the practice of early adopters of the PTP approach. METHODS: A questionnaire containing 8 questions was sent to 50 participants and events involving early adopters of the prone transpsoas technique. Of the 50 surgeons, 32 completed the questionnaire, which totaled 1963 cases of PTP surgeries. RESULTS: Nine of the 32 surgeons experienced a major complication (28%), with persistent neurological deficit being the most frequent (7/9). Of the total number of cases, the occurrence of permanent neurological deficits was approximately 0,6%, and the rate of vascular and visceral injuries were both 0,05% (1/1963 for each case). CONCLUSION: Based on the analysis of the questionnaire responses, it can be concluded that PTP is a safe technique with a very low rate of serious complications. However, future studies with a more heterogeneous group of surgeons and a more rigorous linkage between answers and patient data are needed to support the findings of this study.

Comparison of perioperative outcomes in obese and non-obese patients subjected to open lumbar spine surgery.

OBJECTIVE: Obesity is a global epidemic affecting developing countries. The relationship between obesity and perioperative outcomes during elective lumbar spine surgery remains controversial, especially in those without morbid disease. MATERIALS AND METHODS: We retrospectively revised the medical records of patients with lumbar spine degeneration subjected to elective surgery. The data retrieved included demographic and clinical characteristics, body mass index (BMI), obesity status (BMI ≥ 30), surgical interventions, estimated blood loss (EBL), operative time, length of stay (LOS), and post-operative complications. Perioperative outcomes were compared between Grade I-II obese and non-obese individuals. RESULTS: We enrolled 53 patients, 18 with Grade I-II obesity. Their median age was 51, with no differences in gender, comorbidities, laboratory parameters, and surgical procedures received between groups. No clinically relevant differences were found between grade I-II obese and non-obese participants in EBL (300 mL vs. 250 mL, p = 0.069), operative time (3.2 h vs. 3.0 h, p = 0.037), and LOS (6 days vs. 5 days, p = 0.3). Furthermore, BMI was not associated with the incidence of significant bleeding and long stay but showed a modest correlation with operative time. CONCLUSION: Grade I-II obesity does not increase surgical complexity nor perioperative complications during open lumbar spine surgery.

OBJETIVO: La obesidad es una epidemia mundial que afecta a países subdesarrollados. Su relación con los resultados de la cirugía de columna lumbar electiva sigue siendo controvertida, especialmente en obesos sin enfermedad mórbida. MÉTODOS: Se revisaron los expedientes de pacientes con degeneración de la columna lumbar sometidos a cirugía. Los datos recuperados incluyeron características demográficas y clínicas, índice de masa corporal (IMC), estado de obesidad (IMC > 30), intervenciones quirúrgicas, sangrado estimado, tiempo operatorio, tiempo de estancia y complicaciones. Los resultados se compararon entre individuos obesos grado I-II y controles. RESULTADOS: Se incluyeron 53 pacientes, 18 con obesidad de grado I-II. La edad media fue de 51 años, sin diferencias en el sexo, las comorbilidades, los parámetros de laboratorio y los procedimientos quirúrgicos recibidos entre grupos. No se encontraron diferencias relevantes entre los participantes obesos y los no obesos en sangrado (300 vs. 250 mL, p = 0.069), tiempo operatorio (3.2 vs. 3.0 horas, p = 0.037) y estancia (6 vs. 5 días, p = 0.3). El IMC no se asoció con hemorragia y larga estancia, pero mostró una correlación modesta con el tiempo operatorio. CONCLUSIONES: La obesidad grado I-II no predispone a complicaciones durante la cirugía de columna lumbar.

Minimally Invasive Surgery for Managing Grade IV and V Spondylolisthesis.

Surgical treatment of high-grade spondylolisthesis is controversial and aims at restoring the spinopelvic sagittal balance through complete or partial reduction of the listhesis. Nerve decompression and interbody fusion are necessary for patients presenting with neurological deficit, severe pain, lower limb asymmetry, or deformities. We present the case and the results of a patient with high-grade spondylolisthesis, in whom minimally invasive management was performed. A narrative review in this topic is also provided. We performed a literature review of high-grade spondylolisthesis to compare our technique to current surgical alternatives. We included articles from PubMed, Embase, Scopus, Ovid, and Science Direct published between 1963 and 2022 that were written in English, German, and Spanish. The terms used were the following: "high grade spondylolisthesis," "spondyloptosis," "surgical management," "interbody fusion," and "arthrodesis." In all, 485 articles were displayed, from which we filtered 112 by title and abstract. At the end, 75 references were selected for the review. Different interbody fusion techniques can be used to correct the lumbosacral kyphosis and restore the spinopelvic parameters. A complete reduction of the listhesis is not always required. The surgical procedure carried out in our patient corresponds to the first known case of minimally invasive circumferential arthrodesis with iliac screws and sacral fixation in a high-grade dysplastic spondylolisthesis. This approach guarantees the correction of the lumbosacral kyphosis and a complete reduction of the listhesis. Further studies are required to determine whether the results of this case can be extrapolated to other patients with high-grade spondylolisthesis.

Estudio comparativo entre la fusión lumbar intersomática por vía oblicua y la fusión lumbar intersomática por vía posterior. Resultados radiográficos y clínicos a corto plazo / Comparison between oblique lumbar interbody fusion (OLIF) and posterior lumbar interbody fusion (PLIF). Short-term radiographic and clinical results

Introducción. La fusión lumbar intersomática posterior (PLIF, "posterior lumbar interbody fusion") es un procedimiento ampliamente utilizado. En los últimos años, la fusión lumbar intersomática por vía oblicua (OLIF, "oblique lumbar interbody fusión") ha ganado cierta popularidad dado su abordaje mini-invasivo y su capacidad de descompresión indirecta. Objetivo. Comparar retrospectivamente los resultados clínicos y radiológicos de pacientes operados por vía oblicua y por vía posterior a corto plazo.Materiales y métodos. Se reunieron los pacientes intervenidos quirúrgicamente por vía OLIF y PLIF entre 2020 y 2021. Se dividieron en dos grupos según la vía utilizada y se compararon los datos demográficos y resultados radiográficos entre el preoperatorio y postoperatorio. Se utilizó el cuestionario de Oswestry (ODI) para evaluar la escala de discapacidad por dolor lumbar y se registraron las complicaciones de ambos grupos. Resultados. Sobre 118 pacientes, 56 corresponden a la vía OLIF y 62 al PLIF. Con respecto al ODI, no se registraron diferencias significativas entre ambos grupos previamente ni posterior a la cirugía. El grupo OLIF mostró mejores resultados radiográficos que el grupo PLIF en el posoperatorio, con una diferencia significativa en la lordosis lumbar total (p 0,017). El grupo PLIF mostró un mayor número de complicaciones posoperatorias. Conclusión. La vía OLIF puede ser un método quirúrgico alternativo a la vía posterior tradicional en pacientes con patología degenerativa lumbar. Esta vía permitiría obtener mejores resultados radiográficos con menos complicaciones comparado con la vía tradiciona

Background. Posterior lumbar interbody fusion (PLIF) is a widely used method. In recent years, oblique lumbar interbody fusion (OLIF) has gained some popularity due to its minimally invasive approach and ability of indirect decompression. Objective. Our objective is to compare retrospectively clinical and radiological results of patients operated by boths techniques in the short term.Materials and methods. Patients who underwent surgery by the OLIF and PLIF between 2020 and 2021 were gathered. They were divided into two groups according to the technique used; and demographic data and radiographic results were compared between the preoperative and postoperative periods. The Oswestry Disability Questionnaire (ODI) was used to assess the low back pain disability; and complications were recorded for both groups. Results. Out of 118 patients, 56 correspond to the OLIF group and 62 to the PLIF group. Regarding the ODI, no significant differences were recorded between the two groups before and after surgery. The OLIF group showed better radiographic results than the PLIF group in the postoperative period, with a significant difference in total lumbar lordosis (p 0.017). The PLIF group showed a higher number of postoperative complications. Conclusion: The OLIF approach can be an alternative surgical method to the traditional posterior approach in patients with lumbar degenerative pathology. This technique would allow obtaining better radiographic results with fewer complications compared to the traditional technique

Comparing perioperative and postoperative outcomes and complications of ALIF and LLIF

Purpose: This paper compares anterior lumbar intercorporeal fusion (ALIF) and lateral lumbar intercorporeal fusion (LLIF). LLIF is an approach through the lateral retroperitoneal corridor, transpsoas. ALIF is a described alternative to interbody fusion with approach variations described as retroperitoneal, transperitoneal, open, and laparoscopic. Our objective is to compare complications can occur in both approaches the ALIF and the LLIF, to see what the advantages and disadvantages are during the perioperative and postoperative. Method: This is a literature review article. A MEDLINE search was conducted through PubMed, google scholar, science direct, and Cochrane to identify articles that reported the differences between ALIF, LLIF and other lumbar interbody fusion approaches focusing the complications, cost and length of surgery, length of hospitalization, narcotic use, sagittal balance and surgical technique. Result: There was no overall significant difference in the postoperative narcotic use, fusion rate, and disc height. However, ALIF was seen to have better postoperative sagittal balance. Although long-term complication rates between ALIF and LLIF are not statistically even though the procedures have procedure-specific complications. Intraoperative blood loss and operative time were relatively higher in ALIF than in LLIF. The risk of injury to the lumbar plexus and iliac vessels is relatively higher than ALIF. Conclusion: ALIF and LLIF they are considered safe, effective and non-invasive. Both procedures present their pearls and pitfalls, but LLIF is associated with more complications than ALIF, although they do not present great differences of clinical outcomes. There is a need more extensive research to determine the best approach.

Propósito: Este trabajo compara la fusión intercorpórea lumbar anterior (ALIF, por sus siglas en inglés) y la fusión intercorpórea lumbar lateral (LLIF, por sus siglas en inglés). LLIF es una aproximación a través del corredor retroperitoneal lateral, con transpsoas. La ALIF es una alternativa a la fusión intercorporal con variaciones de abordaje descritas como retroperitoneal, transperitoneal, abierta y laparoscópica. Nuestro objetivo es comparar las complicaciones que pueden ocurrir en ambos abordajes de la ALIF y la LLIF, para ver cuáles son las ventajas y desventajas durante los procesos perioperatorio y postoperatorio. Método: Este es un artículo de revisión de literatura. Se realizó una búsqueda MEDLINE a través de PubMed, Google Scholar, Science Direct y Cochrane para identificar artículos que reportaron las diferencias entre ALIF, LLIF y otros enfoques de fusión intercorporal lumbar enfocándose en las complicaciones, el costo y la duración de la cirugía, duración de la hospitalización, uso de estupefacientes, equilibrio sagital y técnica quirúrgica. Resultado: No hubo diferencia significativa general en el uso posoperatorio de narcóticos, la tasa de fusión y la altura del disco. Sin embargo, se observó que la ALIF tenía un mejor equilibrio sagital postoperatorio. Aunque las tasas de complicaciones a largo plazo entre ALIF y LLIF no son estadísticamente significativas a pesar de que los procedimientos tienen complicaciones específicas del procedimiento. La pérdida de sangre intraoperatoria y el tiempo operativo fueron relativamente más altos en ALIF que en LLIF. El riesgo de lesión en el plexo lumbar y los vasos ilíacos es relativamente mayor que la ALIF. Conclusiones: ALIF y LLIF se consideran métodos seguros, eficaces y no invasivos. Ambos procedimientos presentan aciertos y desaciertos, pero el LLIF se asocia a más complicaciones que el ALIF, aunque no presentan grandes diferencias en los resultados clínicos. Se necesita una investigación más amplia para determinar el mejor enfoque.

Minimally invasive lateral single-position surgery for multilevel degenerative lumbar spine disease: feasibility and perioperative results in a single Latin-American spine center.

INTRODUCTION: Within advances in minimally invasive spine surgery, the implementation of lateral single position (LSP) increases efficiency while limiting complications, avoiding intraoperative repositioning and diminishing surgical time. Most literature describes one-level instrumentation of the lumbar spine; this study includes the use of LSP for multilevel degenerative disease. OBJECTIVE: The objective of the article is to analyze initial clinical results and complications in the use of LSP for multiple level instrumentation in adults with lumbar degenerative disease. METHODS: A retrospective early clinical series was performed for patients who had multiple level instrumentation in LSP between August 2019 and September 2022 at the Hospital Universitario San Ignacio in Bogota, Colombia. Inclusion criteria were patients older than 18 years with symptomatic lumbar degenerative disease, undergoing any combination of multilevel anterior lumbar interbody fusion, lateral lumbar interbody fusion (LLIF) and pedicle screw fixation. RESULTS: Forty patients with an average age of 61.3 years were included, with diagnosis of multilevel degenerative spondylotic changes. Four-, three- and two-level interventions were performed in 52.5, 35 and 12.5%, respectively. Average time per level was 68.9 min, and length of hospital stay had an average of 2.4 days, with all patients starting ambulation within the first postoperative day. CONCLUSION: Procedural time and blood loss were similar to those reported in literature. No severe lesions, postoperative infections or reinterventions took place. Although it was a small number of patients and further clinical trials are needed, LSP for multiple levels is apparently safe with adequate outcomes which may improve efficiency in the operating room.

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.

Spinopelvic Parameters in the Clinical and Functional Outcomes of Patients Submitted to Lumbar Interbody Fusion Surgery ­ A Prospective Study / Parâmetros espinopélvicos nos resultados clínicos e funcionais de pacientes submetidos a fusão intersomática lombar: um estudo prospectivo

Objectives The relevance of spinopelvic parameters in the patients' clinical and functional outcomes has been widely studied in long spinal fusion. Yet, the importance of the spinopelvic parameters in short-segment fusion surgeries needs further investigation. We analyzed the spinopelvic parameters and surgical outcomes of patients undergoing short-segment lumbar interbody fusion. Materials and Methods An observational, prospective study was conducted between January and June 2021. We selected 25 patients with lumbar stenosis, with or without concomitant spondylolisthesis, undergoing transforaminal lumbar interbody fusion. Variables related to the patient, diagnosis, and surgery were collected. The clinical and functional outcomes were assessed using the Visual Analogue Scale for low-back and leg pain and the Oswestry Disability Index (ODI). The surgical outcomes and spinopelvic parameters were analyzed pre- and postoperatively. Results There was a significant clinical and functional improvement after surgery (p < 0.001), with a mean ODI decrease of 63.6%. The variables of obesity, concomitant spondylolisthesis, absence of osteotomy, and two-level fusion were all associated with lower levels of improvement after surgery (p < 0.05). Pelvic incidence minus lumbar lordosis (PI-LL) was the only parameter that significantly changed regarding the pre and postoperative periods (p < 0.05). Before surgery, PI-LL < 10° correlates with less low-back pain after surgery (r » 0.435; p < 0.05). Postoperatively, no correlation was found between surgical outcomes and all the spinopelvic parameters analyzed. Conclusions The clinical and functional outcomes significantly improved with the surgical intervention but did not correlate with the change in spinopelvic parameters. Patients with preoperative PI-LL < 10° seem to benefit the most from surgery, showing greater improvement in back pain.

Objetivos A influência dos parâmetros espinopélvicos nos resultados clínicos e funcionais dos pacientes tem sido amplamente estudada nas cirurgias de fusão espinhal que envolvem longos segmentos. Contudo, a literatura é escassa acerca da fusão de segmentos curtos. Analisamos assim os parâmetros espinopélvicos e os resultados cirúrgicos de pacientes submetidos a fusão intersomática lombar de segmentos curtos. Materiais e Métodos Realizou-se um estudo prospectivo observacional entre janeiro e junho de 2021. Selecionaram-se 25 pacientes com estenose lombar, com ou sem espondilolistese, submetidos a fusão intersomática lombar transforaminal. Colheram-se dados relacionados com o paciente, o diagnóstico e a cirurgia. Os resultados clínicos e funcionais foram avaliados por meio da Escala Visual Analógica para dor lombar e dos membros inferiores e pela Escala de Incapacidade de Oswestry (Oswestry Disability Index, ODI, em inglês). Os resultados cirúrgicos e os parâmetros espinopélvicos foram analisadas no pré e no pós-operatório. Resultados Verificou-se uma melhoria clínica e funcional significativa após a cirurgia (p < 0,001), com redução média do ODI de 63,6%. As variáveis obesidade, espondilolistese concomitante, ausência de osteotomia e fusão de dois níveis associaram-se a menor melhoria no pós-operatório (p < 0,05). O único parâmetro que mudou significativamente antes e após a cirurgia (p < 0,05) foi a incidência pélvica menos a lordose lombar (IP-LL). No pré-operatório, uma IP-LL < 10° correlacionou-se com menos dor lombar após a cirurgia (r » 0,435; p < 0,05). No pós-operatório, não houve correlação entre os resultados clínicos e funcionais e os parâmetros espinopélvicos. Conclusão Os resultados clínicos e funcionais melhoraram significativamente após a cirurgia, mas não se correlacionam com a mudança dos parâmetros espinopélvicos. Pacientes com IP-LL< 10° no pré-operatório apresentam maior melhoria da dor lombar no pós-operatório.

Intraoperative Complications of Anterior Lumbar Interbody Fusion: A 5-Year Experience of a Group of Spine Surgeons Performing Their Own Approaches.

BACKGROUND: Spine surgery has evolved at an accelerated pace, allowing the development of more efficient surgical techniques while providing a decreasing rate of morbimortality. One example of these approaches is the anterior lumbar interbody fusion (ALIF). The aim of this study was to evaluate the surgical complication rate when performing ALIF without the help of a vascular "access" surgeon. METHODS: A retrospective descriptive study was conducted at the Hospital Universitario San Ignacio between 2014 and 2018 and included all patients who underwent ALIF during this time. A nonsystematic review was performed assessing approach-related complications in ALIF and the impact of "access" surgeons in surgical outcomes. RESULTS: A total of 337 patients were included and 508 levels were fused. ALIF was performed as ALIF-360° (27%), ALIF-lateral lumbar interbody fusion (LLIF) (8.9%), and stand-alone ALIF (62%). Most procedures were single-level fusions (51.9%), 45.4% involved 2 levels, and 2.6% were 3-level fusions. The mortality rate was 0%, and only 9 cases of vascular injury were observed and described. Left and common iliac veins were the predominant affected structures. Only a single case required blood transfusion without any other treatment or intensive care unit surveillance. CONCLUSIONS: Our study is consistent with literature reports about ALIF complications, finding an incidence of 1.7%. Therefore, ALIF is an excellent alternative for spine procedures, especially for the levels L5-S1 that require sagittal balance restoration. The approaches were performed without a vascular "access" surgeon and presented complication rates similar to those described in the literature.

How to deal with this complication: Intraoperative anterior cage migration in L5-S1 resolved with a lumbar hybrid fusion technique.

Anterior cage migration is the most infrequent and dangerous complication seen in posterior lumbar interbody fusion (PLIF) procedures. We report the case of a 74-year-old woman who underwent PLIF at the L5-S1 level. During the surgery, one of the PLIF-cages dislodged anteriorly into the abdominal cavity without vascular injury. An anterior retroperitoneal approach to remove the cage and complete the fusion was made. The patient was discharged 2 weeks later with encouraging clinical results. In a patient hemodynamically stable, removing the cage by a vascular surgeon, and complete the Anterior Lumbar Interbody Fusion could be a feasible option at L5-S1.

La migración anterior del implante para fusión lumbar es la complicación más infrecuente y peligrosa asociada a la fusión intersomática posterior (PLIF). Reportamos el caso de un paciente femenino de 74 años, operada de PLIF en L5-S1. Durante la cirugía, una de las cajas usadas migró a la cavidad abdominal, sin ocasionar lesión vascular. Para remover el implante y completar la fusión lumbar un abordaje retroperitoneal anterior fue realizado. La paciente fue egresada 2 semanas después con éxito. En un paciente hemodinamicamente estable, este abordaje puede ser una opción para revertir la complicación y completar la fusión lumbar vía anterior.

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.

Venous anatomy of the lumbar region applied to anterior lumbar interbody fusion (ALIF): Proposal of a new classification.

BACKGROUND: Anterior lumbar interbody fusion (ALIF) is a good alternative for the surgical treatment of lumbar degenerative disc disease. The primary vascular complications regarding this intervention involve the common iliac vein bifurcation complex (CIVC). Currently, no classification system allows defining which patients are more prone to these complications. We aimed to perform a retrospective study evaluating the anatomy of the common iliac CIVC at the L5-S1 disc proposing a novel classification system as it relates to the ALIF difficulty. METHODS: 91 consecutive patients who underwent ALIF at the L5-S1 level were included. We categorize the CIVC at the L5-S1 disc space into four types according to the veins position along the disc space. The patient records were reviewed for demographic information, surgical characteristics, and complications. The surgical difficulty was rated at the end of the procedure. RESULTS: 54% of the patients were women. The mean age was 52.5 ± 14.8 years. Mean surgical bleeding was 152 ml (range 20ml -3000 ml), and mean surgical time was 79 ± 13.3 minutes. Berbeo-Diaz-Vargas (BDV) classification type 4 was found in 43.9% of the patients. The surgical complexity was associated with the bleeding magnitude and surgical time spent (p<0.01), not being related to the corporal mass index or sacral slope. Bleeding magnitude, surgical time, and surgical complexity were significantly related to the BDV classification system (p<0.01). Weighted Cohen´s kappa index for the BDV scale was 0.89 (95% IC 0.822 - 0.974). CONCLUSIONS: BDV scale is a reliable and reproducible tool for the classification of CIVC significantly related to a higher incidence of bleeding, prolonged operating time, and increased perceived difficulty by the surgeon.

The prone transpsoas technique: preliminary radiographic results of a multicenter experience.

INTRODUCTION: The lateral lumbar interbody fusion (LLIF) is a safe and effective technique to treat a vast range of lumbar disorders. However, the technique is also burdened by some problems. A new approach to the lateral lumbar interbody fusion was devised to solve or reduce some of the problems regarding the lateral approach. Its principal difference from the standard LLIF relies on positioning the patient in a prone decubitus, which might lead to an increase in the intradiscal lordosis. METHODS: A retrospective, multicentric, non-randomized study to evaluate segmental and regional lordosis following prone transpsoas (PTP) approach to LLIF. All patients undergoing prone transpsoas surgery at the involved institutions were included. Patients with low-quality images not allowing the measurements of the required spinopelvic parameters were excluded. Measurements included pre- and postoperative index-level segmental lordosis, lumbar lordosis, pelvic incidence, and pelvic tilt. RESULTS: Thirty-two (32) patients were included in the study, in which 23 underwent single-level, six (6) underwent two-level, Two (2) underwent three-level, and one underwent four-level PTP. Mean index level segmental lordosis increased from 8.7° to 14.8°(p < 0.001); lumbar lordosis (L1-S1) increased from 42.1° to 45.8° (p = 0.11), although after excluding an outlier value L1-S1 lordosis results were 41.9° pre-op to 46.7° post-op (p = 0.003). Twenty-two (22) patients had a pre-op PI-LL mismatch of 10° or more, while at the postoperative visit, only 12 patients had a mismatch outside of 10° (p = 0.01). CONCLUSION: The prone transpsoas technique is feasible and is associated with a significant gain of segmental lordosis and correction of spinopelvic alignment parameters.

Prone Transpsoas Technique for Simultaneous Single-Position Access to the Anterior and Posterior Lumbar Spine.

BACKGROUND: Effective decompression, arthrodesis, and correction of spinal conditions frequently utilize operative approaches that expose both the anterior and posterior spinal column. Until now, circumferential spinal column access often requires the surgeon to reposition and drape the patient multiple times or utilize a posterior only approach that has limited anterior correction capability or to utilize a lateral-only approach that complicates otherwise traditional posterior surgical maneuvers. OBJECTIVE: To describe a technique utilizing a single surgical position that enables minimally disruptive anterior column correction with simultaneous access to the posterior spinal column. METHODS: The operative technique for accessing the lateral lumbar interbody space from a prone transpsoas (PTP) approach is described. The rationale for this approach and a representative case example are reviewed. RESULTS: The PTP approach was used to perform an L3-4 and L4-5 interbody fusion in a 71-yr-old female with spondylolisthesis, severe stenosis, and locked facets. The PTP approach enabled efficient completion of an anterior column correction, direct posterior decompression, multi-segment pedicle fixation, and maintenance of alignment, all while in a single prone position. There were no intraoperative or postoperative complications. CONCLUSION: The authors' early experience with the described PTP technique suggests it is not only feasible but offers some advantages, as it allows for single-position surgery maximizing both anterior and posterior column access and corrective techniques. Further follow-up studies of this technique are ongoing.

Endoscopic Transforaminal Lumbar Interbody Fusion With a Single Oblique PEEK Cage and Posterior Supplemental Fixation.

BACKGROUND: To demonstrate the feasibility of an endoscopically assisted minimally invasive surgery transforaminal lumbar interbody fusion (MIS-TLIF) and to study clinical outcomes with the use of a static oblique bullet-shaped cannulated poly-ether-ether-ketone (PEEK) lumbar interbody fusion cage in conjunction with platelet enriched plasma infused allograft cancellous chips and posterior supplemental fixation. METHODS: In this retrospective study of 43 patients who underwent endoscopically assisted MIS-TLIF for spondylolisthesis (53.5%) and stenosis (46.3%), the Oswestry Disability Index, the visual analog scale (VAS) for back and leg pain, and the modified Macnab criteria were used as primary clinical outcome measures. Clinical outcomes were cross-tabulated against fusion grade using the Bridwell classification of interbody fusion. RESULTS: The majority of patients (90.7%) had excellent (8/43; 18.6%) and good (31/43; 72.1%) Macnab outcomes. There were significant VAS back score reductions from an average preoperative values of 8.9070 to a postoperative VAS score of 3.8605, and a score of 2.7674 at final follow-up (P < .0001). The reductions in the VAS leg scores were also significant from preoperative score of 5.58 to a postoperative value of 2.16, and a final follow-up score of 1.67 (P < .0001); the Oswestry Disability Index score went from a preoperative value of 54.4 to 23.3 postoperatively and 18.5 at the final follow-up (P < .0001). The vast majority of patients (92.9%) with Bridwell grade I fusion had excellent and good Macnab outcomes (P = .027). CONCLUSIONS: The authors recommend the use of an endoscope as an adjunct to MIS-TLIF, a minimally invasive spinal surgery technique in which many surgeons may be well versed and have a great deal of experience. Clinical outcomes with the endoscopic interbody fusion procedure with a static PEEK cage in conjunction with platelet-enriched bone allograft were favorable. LEVEL OF EVIDENCE: 3. CLINICAL RELEVANCE: Feasibility study.

A prospective clinical study comparing MI-TLIF with unilateral versus bilateral transpedicular fixation in low grade lumbar spondylolisthesis.

BACKGROUND: Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) has become one of the standard techniques for approaching ipsilateral decompression, anterior column fusion, and posterior stabilization. This procedure is usually accompanied by the placement of bilateral transpedicular screws in the corresponding segment. The purpose of this study was to evaluate the clinical efficacy of unilateral screw fixation compared with bilateral fixation in patients diagnosed with low-grade symptomatic lumbar spondylolisthesis who underwent an MI-TLIF technique. METHODS: A prospective and comparative study was performed in 67 patients with grade 1 symptomatic lumbar spondylolisthesis. The sample was allocated on both unilateral fixation group (n=33) and bilateral fixation group (n=34). Clinical outcomes were evaluated using Oswestry Disability Index (ODI), visual analogue scale (VAS) for leg and back pain, and Short Form 36 Health Survey (SF-36), preoperatively, and at 1, 3, 6, and 12 months postoperatively. Changes over time and differences between the groups were analyzed. Statistical analyses included: Friedman test, Student's t-test and Mann-Whitney's U. A two-tailed P value of <0.05 was considered significant. RESULTS: During 1-year of evaluation there were no significant clinical differences between both groups. CONCLUSIONS: Patients with grade 1 symptomatic lumbar spondylolisthesis treated with MI-TLIF with unilateral screw fixation had similar clinical results than those treated with bilateral fixation at 12 months postoperatively.

Cajas intersomáticas lumbares: ¿medios de fusión o solo espaciadores? / Lumbar interbody cages: fusing means or only spacers?

Introducción: La fusión quirúrgica de la columna lumbar es un método muy utilizado para el tratamiento de la inestabilidad segmentaria lumbar dolorosa. En la actualidad, las dos técnicas de fusión instrumentada más utilizadas son la fusión posterolateral con tornillos pedicula-res y la fusión circunferencial mediante asociación de caja intersomática. Si bien hay evidencia de que la asociación de dispositivos intersomáticos aumenta la tasa de fusión, la mayoría de los estudios no discriminan si esta se produce solo de forma posterolateral o si se asocia una fusión anterior. El objetivo de este trabajo es determinar si existe fusión ósea real a nivel de las cajas intersomáticas o si estas actúan solo como espaciadores. Materiales y métodos: Se analizaron 28 pacientes con patología de la columna lumbar sometidos a artrodesis lumbar circunferencial en un solo nivel entre mayo de 2007 y enero de 2012, mediante tomografía computarizada posquirúrgica para valorar la presencia o no de artrodesis anterior. Se efectuó un estudio de valor terapéutico, descriptivo, de observación (nivel de evidencia IV); mediante evaluación estadística se realizó un análisis de frecuencias para describir la proporción de casos con fusión anterior. Resultados: Se detectó una tasa de fusión del 92,86% y falta de fusión radiológica anterior en el 7,14% de los pacientes. Conclusiones: Hay una alta tasa de fusión anterior a nivel de las cajas intersomáticas; de este modo, se demuestra que dichos dispositivos actúan como medios de fusión y no solo como espaciadores.

Background: Surgical fusion of the lumbar spine is a frequently used method for the treatment of painful lumbar segmental instability; currently the two instrumented fusion techniques most commonly used are posterolateral fusion with pedicle screws, and circumferential fusion by association of interbody cages. Although evidence shows that the association of intersomatic devices increases the fusion rate, most studies do not discriminate if this fusion occurs only posterolaterally, or an anterior fusion also occurs. The aim of this study is to determine if there is a true bone fusion at the level of interbody cages or if they act only as spacers. Methods: We analyzed 28 patients with lumbar spine pathology surgically treated with one level circumferential lumbar fusion from May 2007 to January 2012, using post-surgical computed tomography, to assess the presence or absence of anterior arthrodesis. A therapeutic value, descriptive, observational study was conducted (evidence level IV); by statistical evaluation, frequency analysis was performed to describe the proportion of cases with anterior fusion. Results: The fusion rate reached 92.86%; while there was no anterior radiological fusion in 7.14% of patients. Conclusions: There is a high rate of anterior fusion at the level of the interbody cages, thus demonstrating that these devices act as fusing means and not only as anterior spacers.

Cajas intersomáticas lumbares: ¿medios de fusión o solo espaciadores? / Lumbar interbody cages: fusing means or only spacers?

Introducción: La fusión quirúrgica de la columna lumbar es un método muy utilizado para el tratamiento de la inestabilidad segmentaria lumbar dolorosa. En la actualidad, las dos técnicas de fusión instrumentada más utilizadas son la fusión posterolateral con tornillos pedicula-res y la fusión circunferencial mediante asociación de caja intersomática. Si bien hay evidencia de que la asociación de dispositivos intersomáticos aumenta la tasa de fusión, la mayoría de los estudios no discriminan si esta se produce solo de forma posterolateral o si se asocia una fusión anterior. El objetivo de este trabajo es determinar si existe fusión ósea real a nivel de las cajas intersomáticas o si estas actúan solo como espaciadores. Materiales y métodos: Se analizaron 28 pacientes con patología de la columna lumbar sometidos a artrodesis lumbar circunferencial en un solo nivel entre mayo de 2007 y enero de 2012, mediante tomografía computarizada posquirúrgica para valorar la presencia o no de artrodesis anterior. Se efectuó un estudio de valor terapéutico, descriptivo, de observación (nivel de evidencia IV); mediante evaluación estadística se realizó un análisis de frecuencias para describir la proporción de casos con fusión anterior. Resultados: Se detectó una tasa de fusión del 92,86% y falta de fusión radiológica anterior en el 7,14% de los pacientes. Conclusiones: Hay una alta tasa de fusión anterior a nivel de las cajas intersomáticas; de este modo, se demuestra que dichos dispositivos actúan como medios de fusión y no solo como espaciadores.(AU)

Background: Surgical fusion of the lumbar spine is a frequently used method for the treatment of painful lumbar segmental instability; currently the two instrumented fusion techniques most commonly used are posterolateral fusion with pedicle screws, and circumferential fusion by association of interbody cages. Although evidence shows that the association of intersomatic devices increases the fusion rate, most studies do not discriminate if this fusion occurs only posterolaterally, or an anterior fusion also occurs. The aim of this study is to determine if there is a true bone fusion at the level of interbody cages or if they act only as spacers. Methods: We analyzed 28 patients with lumbar spine pathology surgically treated with one level circumferential lumbar fusion from May 2007 to January 2012, using post-surgical computed tomography, to assess the presence or absence of anterior arthrodesis. A therapeutic value, descriptive, observational study was conducted (evidence level IV); by statistical evaluation, frequency analysis was performed to describe the proportion of cases with anterior fusion. Results: The fusion rate reached 92.86%; while there was no anterior radiological fusion in 7.14% of patients. Conclusions: There is a high rate of anterior fusion at the level of the interbody cages, thus demonstrating that these devices act as fusing means and not only as anterior spacers.(AU)