Comparative Study of S2-Alar-Iliac Screw Trajectories between Males and Females Using Three-Dimensional Computed Tomography Analysis: The True Lateral Angulation of the S2-Alar-Iliac Screw in the Axial Plane

The S2 alar-iliac screw (S2AIS) is commonly used for long spinal fusion as a rigid distal foundation in spinal deformity surgeries, and it is also used in percutaneous sacropelvic fixation for providing an in-line connection to the proximal spinal constructs without using offset connectors. Although the pelvic shape is different between males and females, reports on S2AIS trajectories according to gender have been scarce in the literature. In this paper, S2AIS trajectories are compared between males and females using pelvic three-dimensional computed tomography (3D-CT) in a normal Japanese population. After resetting the caudal angulation in CT-imaging plane manipulation, the angulation of S2AIS was more lateral in the axial plane and more horizontal in the coronal plane in females. Mean distances from the midline to starting points of S2AIS tended to be shorter in females, whereas mean distances from the midline to the posterior superior iliac spine was significantly longer in females. We also found that there were positive correlations between the patients’ height and the maximal lengths of S2AISs, and the patients’ height and minimal areas of S2AIS pathways. Our results are useful not only for conventional open spinal surgery, but also for minimally invasive spine surgery

Computed Tomography-Based Navigation System in Current Spine Surgery: A Narrative Review

The number of spine surgeries using instrumentation has been increasing with recent advances in surgical techniques and spinal implants. Navigation systems have been attracting attention since the 1990s in order to perform spine surgeries safely and effectively, and they enable us to perform complex spine surgeries that have been difficult to perform in the past. Navigation systems are also contributing to the improvement of minimally invasive spine stabilization (MISt) surgery, which is becoming popular due to aging populations. Conventional navigation systems were based on reconstructions obtained by preoperative computed tomography (CT) images and did not always accurately reproduce the intraoperative patient positioning, which could lead to problems involving inaccurate positional information and time loss associated with registration. Since 2006, an intraoperative CT-based navigation system has been introduced as a solution to these problems, and it is now becoming the mainstay of navigated spine surgery. Here, we highlighted the use of intraoperative CT-based navigation systems in current spine surgery, as well as future issues and prospects

Proximal Junctional Failure in Adult Spinal Deformity Surgery: An In-depth Review

Adult spinal deformity (ASD) surgery aims to correct abnormal spinal curvature in adults, leading to improved functionality and reduced pain. However, this surgery is associated with various complications, one of which is proximal junctional failure (PJF). PJF can have a significant impact on a patient’s quality of life, necessitating a comprehensive understanding of its causes and the development of effective management strategies. This review aims to provide an in-depth understanding of PJF in ASD surgery. PJF is a complex complication resulting from a multitude of factors including patient characteristics, surgical techniques, and postoperative management. Age, osteoporosis, overcorrection of sagittal alignment, and poor bone quality are identified as significant risk factors. The clinical implications of PJF are substantial, often requiring revision surgery and causing a considerable decrease in patients’ quality of life. Prevention strategies include careful preoperative planning, appropriate patient selection, and optimization of surgical techniques. Treatment often necessitates a multifaceted approach, including surgical intervention and the management of underlying risk factors. Predictive modeling is an emerging field that may offer a promising avenue for the risk stratification of patients and individualized preventive strategies. A thorough understanding of PJF’s pathogenesis, risk factors, and clinical implications is essential for surgeons involved in ASD surgery. Current preventive measures and treatment strategies aim to mitigate the risk and manage the complications of PJF, but the complication cannot be entirely prevented. Future research should focus on the development of more effective preventive and treatment strategies, and predictive models could be valuable in this pursuit

Respective Correction Rates of Lateral Lumbar Interbody Fusion and Percutaneous Pedicle Screw Fixation for Lumbar Degenerative Spondylolisthesis

Background and Objectives: There are few reports describing the radiographic correction of vertebral slippage in lateral interbody fusion and percutaneous pedicle screw fixation for lumbar degenerative spondylolisthesis. [Objectives] We evaluated the intraoperative surgical correction obtained by lateral interbody fusion and percutaneous pedicle screw procedures. Materials and Methods: Fifty patients were included in this study. According to the Meyerding classification, 35 cases were Grade 1 and 15 cases were Grade 2. Mean age was 64.7 ± 6.4 years old. Seventeen cases were male, and 33 cases were female. The mean preoperative % slip was 21.1 ± 7.0%. After lateral interbody fusion, vertebral slippage was corrected using reduction technique by percutaneous pedicle screw. Results: The slippage of vertebra was reduced to 11.5 ± 6.5% after lateral interbody fusion procedure and 4.0 ± 6.0% after percutaneous pedicle screw procedure. One year after surgery, the slippage of vertebra was 4.1 ± 6.6%. The correction rate of lateral interbody fusion was 47.7 ± 25.1%, and that of percutaneous pedicle screw was 33.8 ± 2.6%. The total correction rate was 81.5 ± 27.7%. There was no significant loss of correction one year after surgery. The Japanese Orthopaedic Association Score significantly improved from 14.7 ± 4.2 to 27.7 ± 1.7 points at final follow up. No vascular or organ injury was observed during surgery, and there were no postoperative surgical site infections or systemic complications. Conclusion: Compared with previous reports, the final correction rate and the correction rate of the percutaneous pedicle screw procedure were particularly high in this study. Lateral interbody fusion and percutaneous pedicle screw using reduction technique provide excellent clinical and radiographic outcomes for patients with lumbar degenerative spondylolisthesis

Minimally Invasive Spine Stabilization for Pyogenic Spondylodiscitis: A 23-Case Series and Review of Literature

Background and Objectives: The incidence of pyogenic spondylodiscitis has been increasing due to the aging of the population. Although surgical treatment is performed for refractory pyogenic spondylodiscitis, surgical invasiveness should be considered. Recent minimally invasive spine stabilization (MISt) using percutaneous pedicle screw (PPS) can be a less invasive approach. The purpose of this study was to evaluate surgical results and clinical outcomes after MISt with PPS for pyogenic spondylodiscitis. Materials and Methods: Clinical data of patients who underwent MISt with PPS for pyogenic spondylitis were analyzed. Results: Twenty-three patients (18 male, 5 female, mean age 67.0 years) were retrospectively enrolled. The mean follow-up period was 15.9 months after surgery. The causative organism was identified in 16 cases (69.6%). A mean number of fixed vertebrae was 4.1, and the estimated blood loss was 145.0 mL. MISt with PPS was successfully performed in 19 of 23 patients (82.6%). Four cases (17.4%) required additional anterior debridement and autologous iliac bone graft placement. CRP levels had become negative at an average of 28.4 days after surgery. There was no major perioperative complication and no screw or rod breakages during follow-up. Conclusions: MISt with PPS would be a less invasive approach for pyogenic spondylodiscitis in elderly or immunocompromised patients

The Short and Intensive Rehabilitation (SHAiR) Program Improves Dropped Head Syndrome Caused by Amyotrophic Lateral Sclerosis: A Case Report

Background and Objectives: Dropped head syndrome (DHS) is a syndrome that presents with correctable cervical kyphotic deformity as a result of weakening cervical paraspinal muscles. DHS with amyotrophic lateral sclerosis (ALS) is a relatively rare condition, and there is no established treatment. This is the first case report describing the improvement of both dropped head (DH) and cervical pain after the short and intensive rehabilitation (SHAiR) program in an ALS patient with DHS. Case Report: After being diagnosed with ALS in June 2020, a 75-year-old man visited our hospital in October 2020 to receive treatment for DHS. At the initial visit, the patient’s DH was prominent during standing and walking. The pain intensity of the neck was 9 out of 10 on the numerical rating scale (NRS), which was indicative of severe pain. The patient was hospitalized for 2 weeks and admitted into the SHAiR program. DH began to decrease one week after undergoing the SHAiR program and improved two weeks later. Neck pain decreased from 9 to 6 on the NRS. Results: The SHAiR program is a rehabilitation program aimed at improving DH in patients with idiopathic DHS. The program was designed to improve neck extensor and flexor function and global spinal alignment, and the program may have contributed to the improvement of DH and neck pain. Currently, reports of conservative therapies for this disease are limited to the use of cervical orthosis. Although further research is needed on the safety and indications of treatment, the SHAiR program may be a viable treatment option

The History and Development of the Percutaneous Pedicle Screw (PPS) System

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) using the SEXTANT® system (Medtronic) featured the first generation of commercially available percutaneous pedicle screw (PPS) system in 2001. The innovative system has since become standard instrumentation used worldwide, and PPS is now used for long-segment minimally invasive surgery (MIS) spinal fixation from the thoracic spine to the pelvis for pathological conditions. PPS systems have been developed for approximately 20 years for the purpose of improving minimally invasive techniques, safety of instrumentation, and ease of use. The third-generation PPS systems established the insertion technique, and the development of the fourth-generation PPS systems have made great strides in minimizing the number of steps in the operative procedure. In the future, PPS systems are expected to continue making use of the latest technological advancements and to develop further with the aim of ensuring greater safety, reducing operator stress, and preventing complications such as insertion errors and infection. In this review article, we describe the historical evolution from the first-generation PPS system to the current PPS systems used today

Surgeons' exposure to radiation in single- and multi-level minimally invasive transforaminal lumbar interbody fusion; a prospective study.

Although minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) has widely been developed in patients with lumbar diseases, surgeons risk exposure to fluoroscopic radiation. However, to date, there is no studies quantifying the effective dose during MIS-TLIF procedure, and the radiation dose distribution is still unclear. In this study, the surgeons' radiation doses at 5 places on the bodies were measured and the effective doses were assessed during 31 consecutive 1- to 3-level MIS-TLIF surgeries. The operating surgeon, assisting surgeon, and radiological technologist wore thermoluminescent dosimeter on the unshielded thyroid, chest, genitals, right middle finger, and on the chest beneath a lead apron. The doses at the lens and the effective doses were also calculated. Mean fluoroscopy times were 38.7, 53.1, and 58.5 seconds for 1, 2, or 3 fusion levels, respectively. The operating surgeon's mean exposures at the lens, thyroid, chest, genitals, finger, and the chest beneath the shield, respectively, were 0.07, 0.07, 0.09, 0.14, 0.32, and 0.05 mSv in 1-level MIS-TLIF; 0.07, 0.08, 0.09, 0.18, 0.34, and 0.05 mSv in 2-level; 0.08, 0.09, 0.14, 0.15, 0.36, and 0.06 mSv in 3-level; and 0.07, 0.08, 0.10, 0.15, 0.33, and 0.05 mSv in all cases. Mean dose at the operating surgeon's right finger was significantly higher than other measurements parts (P<0.001). The operating surgeon's effective doses (0.06, 0.06, and 0.07 mSv for 1, 2, and 3 fusion levels) were low, and didn't differ significantly from those of the assisting surgeon or radiological technologist. Revision MIS-TLIF was not associated with higher surgeons' radiation doses compared to primary MIS-TLIF. There were significantly higher surgeons' radiation doses in over-weight than in normal-weight patients. The surgeons' radiation exposure during MIS-TLIF was within the safe level by the International Commission on Radiological Protection's guidelines. The accumulated radiation exposure, especially to surgeon's hands, should be carefully monitored

Association between the Horizontal Gaze Ability and Physical Characteristics of Patients with Dropped Head Syndrome

Background and Objectives: Patients with dropped head syndrome exhibit weakness of the cervical paraspinal muscles. However, the relationship between horizontal gaze disorder and physical function remains unclear. This study aimed to examine and clarify this relationship. Materials and Methods: Ninety-six patients with dropped head syndrome were included. We measured the McGregor&rsquo;s Slope and investigated physical characteristics, including cervical muscle strength, back muscle strength, and walking ability. Factor analysis was used to classify the characteristics of physical function, and a linear multiple regression analysis was used to evaluate independent variables explaining the variance in the McGregor&rsquo;s Slope. The physical functions of DHS patients were classified into three categories by factor analysis: limb and trunk muscle strength, walking ability, and neck muscle strength. Results: The average value of the McGregor&rsquo;s Slope was 22.2 &plusmn; 24.0 degrees. As a result of multiple regression analysis, walking speed (&beta; = &minus;0.46) and apex (&beta; = &minus;0.30) were extracted as significant factors influencing the McGregor&rsquo;s Slope. Conclusions: Horizontal gaze disorders are not associated with cervical muscle strength but with the walking ability and the alignment type of dropped head syndrome

A rare case of intradural and extramedullary epidermoid cyst after repetitive epidural anesthesia: case report and review of the literature

Abstract Background Spinal epidermoid cysts are benign tumors, which are rarely seen as an intradural extramedullary spinal cord tumor in the conus medullaris region. Acquired spinal epidermoid cysts are mostly caused by iatrogenic procedures, such as lumbar puncture, and the majority of acquired spinal epidermoid cysts have been reported below the L1 level, because lumbar puncture is usually performed around the iliac crest. Here, we report an extremely rare case of an epidermoid cyst that occurred as an intradural and extramedullary spinal cord tumor attached to the conus medullaris after repetitive epidural anesthesia. Case presentation A 67-year-old female presented with a low back pain and left sciatica. Although the patient had experienced occasional mild low back pain for several years, her low back pain markedly worsened 2 months before her visit, as well as newly developed left sciatica resulting in intermittent claudication. She had a history of several abdominal surgeries. All abdominal procedures were performed under general anesthesia with epidural anesthesia in her thoracolumbar spine. Magnetic resonance imaging of her lumbar spine demonstrated an intradural extramedullary spinal cord tumor at the T12–L1 level. Because her symptoms deteriorated, the tumor excision was performed using microscopy. Histological examination of the specimens demonstrated that the cyst walls lined with stratified squamous keratinizing epithelium surrounded by the outer layer of collagenous tissue with the absence of skin adnexa. A diagnosis of epidermoid cysts was confirmed. Her MRI showed complete resection of the tumor, and there was no recurrence at 2-year follow-up. Conclusions In this case report, epidermoid cells might be contaminated into the spinal canal during repetitive epidural anesthesia. The patient was successfully treated by complete resection, and there was no recurrence at 2-year follow-up with a good clinical outcome. However, long-term follow-up is required for a potential risk of tumor recurrence