Complications associated with subaxial placement of pedicle screws versus lateral mass screws in the cervical spine (C2-T1): systematic review and meta-analysis comprising 4,165 patients and 16,669 screws.

Lateral mass screw (LMS) and cervical pedicle screw (CPS) fixation are among the most popular techniques for posterior fusion of the cervical spine. Early research prioritized the LMS approach as the trajectory resulted in fewer neurovascular complications; however, with the incorporation of navigation assistance, the CPS approach should be re-evaluated. Our objective was to report the findings of a meta-analysis focused on comparing the LMS and CPS techniques in terms of rate of various complications with inclusion of all levels from C2 to T1. We conducted a systematic review of PubMed and EMBASE databases with final inclusion criteria focused on identifying studies that reported outcomes and complications for either the CPS or LMS technique. These studies were then pooled, and statistical analyses were performed from the cumulative data. A total of 60 studies comprising 4165 participants and 16,669 screws placed within the C2-T1 levels were identified. Within these studies, the LMS group had a significantly increased odds for lateral mass fractures (odds ratio [OR] = 43.2, 95% confidence interval [CI] = 2.62-711.42), additional cervical surgeries (OR = 5.56, 95%CI = 2.95-10.48), and surgical site infections (SSI) (OR = 5.47, 95%CI = 1.65-18.16). No other significant differences between groups in terms of complications were identified. Within the subgroup analysis of navigation versus non-navigation-guided CPS placement, no significant differences were identified for individual complications, although collectively significantly fewer complications occurred with navigation (OR = 5.29, 95%CI = 2.03-13.78). The CPS group had significantly fewer lateral mass fractures, cervical revision surgeries, and SSIs. Furthermore, navigation-assisted CPS placement was associated with a significant reduction in complications overall.

Risk factors of early complications after thoracic and lumbar spinal deformity surgery: a systematic review and meta-analysis.

PURPOSE: To determine risk factors increasing susceptibility to early complications (intraoperative and postoperative within 6 weeks) associated with surgery to correct thoracic and lumbar spinal deformity. METHODS: We systematically searched the PubMed and EMBASE databases for studies published between January 1990 and September 2021. Observational studies evaluating predictors of early complications of thoracic and lumbar spinal deformity surgery were included. Pooled odds ratio (OR) or standardized mean difference (SMD) with 95% confidence intervals (CI) was calculated via the random effects model. RESULTS: Fifty-two studies representing 102,432 patients met the inclusion criteria. Statistically significant patient-related risk factors for early complications included neurological comorbidity (OR = 3.45, 95% CI 1.83-6.50), non-ambulatory status (OR = 3.37, 95% CI 1.96-5.77), kidney disease (OR = 2.80, 95% CI 1.80-4.36), American Society of Anesthesiologists score > 2 (OR = 2.23, 95% CI 1.76-2.84), previous spine surgery (OR = 1.98, 95% CI 1.41-2.77), pulmonary comorbidity (OR = 1.94, 95% CI 1.21-3.09), osteoporosis (OR = 1.60, 95% CI 1.17-2.20), cardiovascular diseases (OR = 1.46, 95% CI 1.20-1.78), hypertension (OR = 1.37, 95% CI 1.23-1.52), diabetes mellitus (OR = 1.84, 95% CI 1.30-2.60), preoperative Cobb angle (SMD = 0.43, 95% CI 0.29, 0.57), number of comorbidities (SMD = 0.41, 95% CI 0.12, 0.70), and preoperative lumbar lordotic angle (SMD = - 0.20, 95% CI - 0.35, - 0.06). Statistically significant procedure-related factors were fusion extending to the sacrum or pelvis (OR = 2.53, 95% CI 1.53-4.16), use of osteotomy (OR = 1.60, 95% CI 1.12-2.29), longer operation duration (SMD = 0.72, 95% CI 0.05, 1.40), estimated blood loss (SMD = 0.46, 95% CI 0.07, 0.85), and number of levels fused (SMD = 0.37, 95% CI 0.03, 0.70). CONCLUSION: These data may contribute to development of a systematic approach aimed at improving quality-of-life and reducing complications in high-risk patients.

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.

Incidence of major and minor vascular injuries during lateral access lumbar interbody fusion procedures: a retrospective comparative study and systematic literature review.

During lateral lumbar fusion, the trajectory of implant insertion approaches the great vessels anteriorly and the segmental arteries posteriorly, which carries the risk of vascular complications. We aimed to analyze vascular injuries for potential differences between oblique lateral interbody fusion (OLIF) and lateral lumbar interbody fusion (LLIF) procedures at our institution. This was coupled with a systematic literature review of vascular complications associated with lateral lumbar fusions. A retrospective chart review was completed to identify consecutive patients who underwent lateral access fusions. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used for the systematic review with the search terms "vascular injury" and "lateral lumbar surgery." Of 260 procedures performed at our institution, 211 (81.2%) patients underwent an LLIF and 49 (18.8%) underwent an OLIF. There were no major vascular complications in either group in this comparative study, but there were four (1.5%) minor vascular injuries (2 LLIF, 0.95%; 2 OLIF, 4.1%). Patients who experienced vascular injury experienced a greater amount of blood loss than those who did not (227.5 ± 147.28 vs. 59.32 ± 68.30 ml) (p = 0.11). In our systematic review of 63 articles, major vascular injury occurred in 0-15.4% and minor vascular injury occurred in 0-6% of lateral lumbar fusions. The systematic review and comparative study demonstrate an increased rate of vascular injury in OLIF when compared to LLIF. However, vascular injuries in either procedure are rare, and this study aids previous literature to support the safety of both approaches.

Complications associated with subaxial placement of pedicle screws versus lateral mass screws in the cervical spine: systematic review and meta-analysis comprising 1768 patients and 8636 screws.

Lateral mass screw (LMS) fixation for the treatment of subaxial cervical spine instability or deformity has been traditionally associated with few neurovascular complications. However, cervical pedicle screw (CPS) fixation has recently increased in popularity, especially with navigation assistance, because of the higher pullout strength of the pedicle screws. To their knowledge, the authors conducted the first meta-analysis comparing the complication rates during and/or after CPS and LMS placement for different pathologies causing cervical spine instability. A systematic literature search of PubMed and Embase from inception to January 12, 2021 was performed to identify studies reporting CPS and/or LMS-related complications. Complications were categorized into intraoperative and early postoperative (within 30 days of surgery) and late postoperative (after 30 days from surgery) complications. All studies that met the prespecified inclusion criteria were pooled and cumulatively analyzed. A total of 24 studies were conducted during the time frame of the search and comprising 1768 participants and 8636 subaxially placed screws met the inclusion criteria. The CPS group experienced significantly more postoperative C5 palsy (odds ratio [OR] = 3.48, 95% confidence interval [CI] = 1.27-9.53, p < 0.05). Otherwise, there were no significant differences between the LMS and CPS groups. There were no significant differences between the CPS and LMS groups in terms of neurovascular procedure-related complications other than significantly more C5 palsy in the CPS group.

Meta-analysis of overall survival and postoperative neurologic deficits after resection or biopsy of butterfly glioblastoma.

Butterfly glioblastoma (bGBM) is a grade 4 glioma with a poor prognosis. Surgical treatment of these cancers has been reviewed in the literature with some recent studies supporting resection as a safe and effective treatment instead of biopsy and adjuvant therapy. This meta-analysis was designed to determine whether there are significant differences in overall survival (OS) and postoperative neurologic deficits (motor, speech, and cranial nerve) following intervention in patients who underwent tumor resection as part of their treatment, compared to patients who underwent biopsy without surgical resection. A literature search was conducted using PubMed (National Library of Medicine) and Embase (Elsevier) to identify articles from each database's earliest records to May 25, 2021, that directly compared the outcomes of biopsy and resection in bGBM patients and met predetermined inclusion criteria. A meta-analysis was conducted to compare the effects of the two management strategies on OS and postoperative neurologic deficits. Six articles met our study inclusion criteria. OS was found to be significantly longer for the resection group at 6 months (odds ratio [OR] 2.94, 95% confidence interval [CI] 1.23-7.05) and 12 months (OR 3.75, 95% CI 1.10-12.76) than for the biopsy group. No statistically significant differences were found in OS at 18 and 24 months. Resection was associated with an increased rate of postoperative neurologic deficit (OR 2.05, 95% CI 1.02-4.09). Resection offers greater OS up to 1 year postintervention than biopsy alone; however, this comes at the cost of higher rates of postoperative neurologic deficits.

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.

CT-to-fluoroscopy registration versus scan-and-plan registration for robot-assisted insertion of lumbar pedicle screws.

OBJECTIVE: Pedicle screw insertion for stabilization after lumbar fusion surgery is commonly performed by spine surgeons. With the advent of navigation technology, the accuracy of pedicle screw insertion has increased. Robotic guidance has revolutionized the placement of pedicle screws with 2 distinct radiographic registration methods, the scan-and-plan method and CT-to-fluoroscopy method. In this study, the authors aimed to compare the accuracy and safety of these methods. METHODS: A retrospective chart review was conducted at 2 centers to obtain operative data for consecutive patients who underwent robot-assisted lumbar pedicle screw placement. The newest robotic platform (Mazor X Robotic System) was used in all cases. One center used the scan-and-plan registration method, and the other used CT-to-fluoroscopy for registration. Screw accuracy was determined by applying the Gertzbein-Robbins scale. Fluoroscopic exposure times were collected from radiology reports. RESULTS: Overall, 268 patients underwent pedicle screw insertion, 126 patients with scan-and-plan registration and 142 with CT-to-fluoroscopy registration. In the scan-and-plan cohort, 450 screws were inserted across 266 spinal levels (mean 1.7 ± 1.1 screws/level), with 446 (99.1%) screws classified as Gertzbein-Robbins grade A (within the pedicle) and 4 (0.9%) as grade B (< 2-mm deviation). In the CT-to-fluoroscopy cohort, 574 screws were inserted across 280 lumbar spinal levels (mean 2.05 ± 1.7 screws/ level), with 563 (98.1%) grade A screws and 11 (1.9%) grade B (p = 0.17). The scan-and-plan cohort had nonsignificantly less fluoroscopic exposure per screw than the CT-to-fluoroscopy cohort (12 ± 13 seconds vs 11.1 ± 7 seconds, p = 0.3). CONCLUSIONS: Both scan-and-plan registration and CT-to-fluoroscopy registration methods were safe, accurate, and had similar fluoroscopy time exposure overall.

Predicting prolonged length of stay in patients undergoing transforaminal lumbar interbody fusion.

BACKGROUND: With growing emphasis on high-value care, many institutions have been working on improving surgical efficiency, quality, and complication reduction. Unfortunately, data are limited regarding perioperative factors that may influence length of stay (LOS) following transforaminal lumbar interbody fusion (TLIF). We sought to design a predictive algorithm that determined patients at risk of prolonged LOS after TLIF. The goal was to identify patients who would benefit from preoperative intervention aimed to reduce LOS. METHODS: We conducted a review of perioperative data for patients who underwent TLIF between 2014 and 2019. Univariate and multivariate stepwise regression models were used to analyze risk factor effects on postoperative LOS. RESULTS: Two hundred and sixty-nine patients were identified (57.2% women). Mean age at surgery was 61.7 ± 12.3 years. Mean postoperative LOS was 3.08 ± 1.54 days. In multivariate analysis, American Society of Anesthesiologists class (odds ratio [OR] = 1.441, 95% confidence interval [CI] 1.321-1.571), preoperative functional status (OR = 1.237, 95% CI 1.122-1.364), Oswestry Disability Index (OR = 1.010, 95% CI 1.004-1.016), and estimated blood loss (OR = 1.050, 95% CI 1.003-1.101) were independent risk factors for postoperative LOS ≥ 5 days. The final model had an area under the curve of 0.948 with good discrimination and was implemented in the form of an online calculator ( https://spine.shinyapps.io/TLIF_LOS/ ). CONCLUSION: The prediction tool derived can be useful for assessing likelihood of prolonged LOS in patients undergoing TLIF. With external validation, this calculator may ultimately assist healthcare providers in identifying patients at risk for prolonged hospitalization so preoperative interventions can be undertaken to reduce LOS, thus reducing resource utilization.

The role of steroid administration in the management of dysphagia in anterior cervical procedures.

Dysphagia is a common postoperative symptom for patients undergoing anterior cervical spine procedures. The purpose of this study is to present the current literature regarding the effect of steroid administration in dysphagia after anterior cervical spine procedures. We performed a literature search in the PubMed database, using the following terms: "dysphagia," "ACDF," "cervical," "surgery," "anterior," "spine," "steroids," "treatment," and "complications." We included in our review any study correlating postoperative dysphagia and steroid administration in anterior cervical spine surgery. Studies, which did not evaluate, pre- and postoperatively, dysphagia with a specific clinical or laboratory methodology were excluded from our literature review. Five studies were included in our results. All were randomized, prospective studies, with one being double blinded. Steroid administration protocol was different in every study. In two studies, dexamethasone was used. Methylprednisolone was administrated in three studies. In four studies, steroids were applied intravenously, while in one study, locally in the retropharyngeal space. Short-term dysphagia and prevertebral soft tissue edema were diminished by steroid administration, according to the results of two studies. In one study, prevertebral soft tissue edema was not affected by the steroid usage. Furthermore, short-term osseous fusion rate was impaired by the steroid administration, according to the findings of one study. The usage of steroids in patients undergoing anterior cervical spine procedures remains controversial. Multicenter, large-scale, randomized, prospective studies applying the same protocol of steroid administration and universal outcome criteria should be performed for extracting statistically powerful and clinically meaningful results.

The role of diffusion tensor imaging and fractional anisotropy in the evaluation of patients with idiopathic normal pressure hydrocephalus: a literature review.

OBJECTIVE Diffusion tensor imaging (DTI) for the assessment of fractional anisotropy (FA) and involving measurements of mean diffusivity (MD) and apparent diffusion coefficient (ADC) represents a novel, MRI-based, noninvasive technique that may delineate microstructural changes in cerebral white matter (WM). For example, DTI may be used for the diagnosis and differentiation of idiopathic normal pressure hydrocephalus (iNPH) from other neurodegenerative diseases with similar imaging findings and clinical symptoms and signs. The goal of the current study was to identify and analyze recently published series on the use of DTI as a diagnostic tool. Moreover, the authors also explored the utility of DTI in identifying patients with iNPH who could be managed by surgical intervention. METHODS The authors performed a literature search of the PubMed database by using any possible combinations of the following terms: "Alzheimer's disease," "brain," "cerebrospinal fluid," "CSF," "diffusion tensor imaging," "DTI," "hydrocephalus," "idiopathic," "magnetic resonance imaging," "normal pressure," "Parkinson's disease," and "shunting." Moreover, all reference lists from the retrieved articles were reviewed to identify any additional pertinent articles. RESULTS The literature search retrieved 19 studies in which DTI was used for the identification and differentiation of iNPH from other neurodegenerative diseases. The DTI protocols involved different approaches, such as region of interest (ROI) methods, tract-based spatial statistics, voxel-based analysis, and delta-ADC analysis. The most studied anatomical regions were the periventricular WM areas, such as the internal capsule (IC), the corticospinal tract (CST), and the corpus callosum (CC). Patients with iNPH had significantly higher MD in the periventricular WM areas of the CST and the CC than had healthy controls. In addition, FA and ADCs were significantly higher in the CST of iNPH patients than in any other patients with other neurodegenerative diseases. Gait abnormalities of iNPH patients were statistically significantly and negatively correlated with FA in the CST and the minor forceps. Fractional anisotropy had a sensitivity of 94% and a specificity of 80% for diagnosing iNPH. Furthermore, FA and MD values in the CST, the IC, the anterior thalamic region, the fornix, and the hippocampus regions could help differentiate iNPH from Alzheimer or Parkinson disease. Interestingly, CSF drainage or ventriculoperitoneal shunting significantly modified FA and ADCs in iNPH patients whose condition clinically responded to these maneuvers. CONCLUSIONS Measurements of FA and MD significantly contribute to the detection of axonal loss and gliosis in the periventricular WM areas in patients with iNPH. Diffusion tensor imaging may also represent a valuable noninvasive method for differentiating iNPH from other neurodegenerative diseases. Moreover, DTI can detect dynamic changes in the WM tracts after lumbar drainage or shunting procedures and could help identify iNPH patients who may benefit from surgical intervention.

Patient variables and referral paradigms associated with osteoporosis screening and treatment in neurosurgical patients undergoing kyphoplasty.

OBJECT Vertebral fractures are the most common osteoporotic fracture. Bone density testing and medical treatment with bisphosphonates or parathormone are recommended for all patients with an osteoporotic fracture diagnosis. Inadequate testing and treatment of patients presenting with low-impact fractures have been reported in various specialties. Similar data are not available from academic neurosurgery groups. The authors assessed compliance with treatment and testing of osteoporosis in patients with vertebral compression fractures evaluated by the authors' academic neurosurgery service, and patient variable and health-systems factors associated with improved compliance. METHODS Data for patients who underwent percutaneous kyphoplasty for compression fractures was retrospectively collected. Diagnostic and medical interventions were tabulated. Pre-, intra-, and posthospital factors that had been theorized to affect the compliance of patients with osteoporosis-related therapies were tabulated and statistically analyzed. RESULTS Less than 50% of patients with kyphoplasty received such therapies. Age was not found to correlate with other variables. Referral from a specialist rather than a primary care physician was associated with a higher rate of bone density screening, as well as vitamin D and calcium therapy, but not bisphosphonate/parathormone therapy. Patients who underwent preoperative evaluation by their primary care physician were significantly more likely to receive bisphosphonates compared with those only evaluated by a hospitalist. Patients with unprovoked fractures were more likely to undergo multiple surgeries compared with those with minor trauma. CONCLUSIONS These results suggest poor compliance with current standard of care for medical therapies in patients with osteoporotic compression fractures undergoing kyphoplasty under the care of an academic neurosurgery service.

Supraclavicular Artery Island Flap for Treatment of Cervical Wound Defects and Persistent Cerebrospinal Fluid Leaks: A Technical Note and Systematic Review of the Literature.

BACKGROUND: Soft tissue defects and persistent cerebrospinal fluid (CSF) leaks can create complications after cervical spinal surgery. The supraclavicular artery island (SAI) flap is useful in closing tissue defects, particularly in these complex surgeries and multiple reinterventions. However, technical reports in this context are scarce. We describe application of the SAI flap technique to control persistent CSF leak in the first documented instance (to our knowledge) of a low-grade fibromyxoid sarcoma (LGFMS) in the cervical epidural space. Additionally, we conducted a comprehensive review of PubMed, Embase, and Google Scholar from their earliest records through December 17, 2023 using combined terms, "supraclavicular artery island flap AND spine" and "supraclavicular AND flap AND spine". TECHNICAL NOTE: A 56-year-old woman with arm pain and weakness presented with a cervical epidural mass extending from C4-C6 and associated spinal cord compression. She underwent a 3-level corpectomy and tumor resection. Primary dural closure was impossible due to the dural invasion, and reintervention with an SAI flap and definitive lumboperitoneal shunting were required to control and seal the CSF leak. SYSTEMATIC LITERATURE REVIEW: Seven case reports describing SAI flap for spinal surgery complications were identified. The indications in those cases were correcting esophageal and hypopharyngeal perforations after cervical fusion and discectomy and persistent soft tissue coverage after cervical instrumentation. CONCLUSIONS: The SAI flap technique provided wound defect coverage in this case and is suitable for addressing issues such as persistent CSF leaks or soft tissue coverage after cervical spine surgery.

Cervical Vertebral Bone Quality Score Independently Predicts Distal Junctional Kyphosis After Posterior Cervical Fusion.

BACKGROUND AND OBJECTIVE: Posterior cervical fusion is the surgery of choice when fusing long segments of the cervical spine. However, because of the limited presence of this pathology, there is a paucity of data in the literature about the postoperative complications of distal junctional kyphosis (DJK). We aimed to identify and report potential associations between the preoperative cervical vertebral bone quality (C-VBQ) score and the occurrence of DJK after posterior cervical fusion. METHODS: The authors retrospectively reviewed records of patients who underwent posterior cervical fusion at a single hospital between June 1, 2010, and May 31, 2020. Patient data were screened to include patients who were >18 years old, had baseline MRI, had baseline standing cervical X-ray, had immediate postoperative standing cervical X-ray, and had clinical and radiographic follow-ups of >1 year, including a standing cervical X-ray at least 1 year postoperatively. Univariate analysis was completed between DJK and non-DJK groups, with multivariate regression completed for relevant clinical variables. Simple linear regression was completed to analyze correlation between the C-VBQ score and total degrees of kyphosis angle change. RESULTS: Ninety-three patients were identified, of whom 19 (20.4%) had DJK and 74 (79.6%) did not. The DJK group had a significantly higher C-VBQ score than the non-DJK group (2.97 ± 0.40 vs 2.26 ± 0.46; P < .001). A significant, positive correlation was found between the C-VBQ score and the total degrees of kyphosis angle change (r 2 = 0.26; P < .001). On multivariate analysis, the C-VBQ score independently predicted DJK (odds ratio, 1.46; 95% CI, 1.27-1.67; P < .001). CONCLUSION: We found that the C-VBQ score was an independent predictive factor of DJK after posterior cervical fusion.

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.

Tension Parameters of Junctional Tethers in Proximal Junction Kyphosis: A Cadaveric Biomechanical Study.

OBJECTIVE: Proximal junctional failure following surgical correction for adult spinal deformity significantly impacts quality of life and increases the economic burden of treating underlying spinal deformity. The objective of this cadaver study was to determine optimal tension parameters in junctional tethers for proximal junctional kyphosis prevention. METHODS: Cadaveric specimens were used to establish the optimal tension range in polyethylene tethering devices, such as the VersaTie (NuVasive) used in this study. Three specimens were instrumented to test tether tensions of 0, 75, and 150 Newtons (N) at L1-L2, T9-T10, and T3-T4. An optical tracking system was used to measure when specimens reached proximal junctional kyphosis, experienced instrumentation or tissue failure, or reached a cap of 2500 cycles. Radiographs were obtained before and after testing. RESULTS: At all levels, use of a tether at tension forces of 75 N and 150 N elicited a protective effect. The only level in which a higher tension on the tether resulted in more protection was at T3-T4. When averaged, the use of a tether at tension forces of 75 N and 150 N showed 1000 cycles of protection at L1-L2, 2000 cycles at T9-T10, and 1426 cycles at T3-T4. Radiographic analysis corroborated these findings. CONCLUSIONS: The use of a tether in a cadaveric model prevents the development of proximal junctional kyphosis across all tested levels and an increased tension force of 150 N is protective at the proximal thoracic spine. These data can be used to develop further models for a tether system that reproducibly applies a fixed tension force above the thoracolumbar rod construct.

Pack Years of Tobacco Cigarette Smoking as a Predictor of Bony Fusion after Anterior Cervical Discectomy and Fusion.

OBJECTIVE: Smoking tobacco cigarettes negatively impacts bone healing after spinal fusion. Smoking history is often assessed based on current smoker and nonsmoker status. However, in current research, smoking history has not been quantified in terms of pack years to estimate lifetime exposure and assess its effects. Our goal was to investigate the influence of smoking history, quantified in pack years, on bony fusion after anterior cervical discectomy and fusion (ACDF). METHODS: A retrospective chart review of consecutive patients who underwent ACDF for cervical disc degeneration between September 21, 2017 and October 17, 2018 was conducted. Patient demographics, procedural variables, and postoperative outcomes were analyzed. Multivariate logistic regression analysis was performed to identify predictive factors for bony fusion following ACDF. Receiver operating characteristic curve analysis was used to determine the optimal discrimination threshold for smoking history pack years in association with nonfusion. RESULTS: Among 97 patients identified, 90 (93%) demonstrated bony fusion on postoperative imaging. Mean number of smoking history pack years was 6.1 ± 13 for the fusion group and 16 ± 21 for the nonfusion group. Multivariate logistic regression analysis suggested that increased pack years of tobacco cigarette smoking was a significant predictor of nonfusion (95% confidence interval, [1.0,1.1], P = 0.045). The receiver operating characteristic curve analysis revealed that 6.1 pack years best stratified the risk for nonfusion (area under the curve, 0.8). CONCLUSIONS: Patients with a history of tobacco cigarette smoking ≥6.1 pack years may have an increased risk of nonfusion after ACDF.

Comparative analysis of patient demographics, perioperative outcomes, and adverse events after lumbar spinal fusion between urban and rural hospitals: an analysis of the National Inpatient Sample (NIS) database.

OBJECTIVE: Rural location of a patient's primary residence has been associated with worse clinical and surgical outcomes due to limited resource availability in these parts of the US. However, there is a paucity of literature investigating the effect that a rural hospital location may have on these outcomes specific to lumbar spine fusions. METHODS: Using the National Inpatient Sample (NIS) database, we identified all patients who underwent primary lumbar spinal fusion in the years between 2009 and 2020. Patients were separated according to whether the operative hospital was considered rural or urban. Univariable and multivariable regression models were used for data analysis. RESULTS: Of 2,863,816 patients identified, 120,298 (4.2 %) had their operation at a rural hospital, with the remaining in an urban hospital. Patients in the urban cohort were younger (P < .001), more likely to have private insurance (39.81 % vs 31.95 %, P < .001), and fewer of them were in the first (22.52 % vs 43.00 %, P < .001) and second (25.96 % vs 38.90 %, P < .001) quartiles of median household income compared to the rural cohort. The urban cohort had significantly increased rates of respiratory (4.49 % vs 3.37 %), urinary (5.25 % vs 4.15 %), infectious (0.49 % vs 0.32 %), venous thrombotic (0.57 % vs 0.24 %, P < .001), and neurological (0.79 % vs 0.36 %) (all P < .001) perioperative complications. On multivariable analysis, the urban cohort had significantly increased odds of the same perioperative complications: respiratory (odds ratio[OR] = 1.48; 95 % confidence interval [CI], 1.26-1.74), urinary (OR = 1.34; 95 %CI, 1.20-1.50), infection (OR = 1.63; 95 %CI, 1.23-2.17), venous thrombotic (OR = 1.79; 95 %CI, 1.32-2.41), neurological injury (OR = 1.92; 95 %CI, 1.46-2.53), and localized infection (OR = 1.65; 95 %CI, 1.25-2.17) (all P < .001). CONCLUSIONS: Patients undergoing lumbar fusions experience significantly different outcomes based on the rural or urban location of the operative hospital.

Comparative Analysis of the 3 Cervical Vertebral Bone Quality (C-VBQ) Score Methodologies and Their Correlations to the Lumbar Vertebral Bone Quality (VBQ) Score.

OBJECTIVE: Common complications after spinal fusion, such as pseudoarthrosis, cage subsidence, or instrumentation failure, are affected by patients' bone quality. The cervical-vertebral bone quality (C-VBQ) score, a magnetic resonance imaging (MRI)-based adaption of the lumbar vertebral bone quality (VBQ) score, was developed by 3 separate research groups simultaneously to evaluate bone quality in cervical spinal fusion patients. We present the first analysis comparing these scoring methods to the well-validated VBQ score. METHODS: A retrospective analysis of data for consecutive patients who underwent spine surgery at a single institution was completed. The VBQ score was calculated using the Ehresman et al. METHOD: The C-VBQ scores, named according to placement of the region of interest within the cerebral spinal fluid, were calculated separately using the methods of Soliman et al. (C2-VBQ), Razzouk et al. (C5-VBQ), and Huang et al. (T1-VBQ). Linear regression models were utilized to evaluate correlations to the VBQ score. RESULTS: A total of 105 patients were identified (mean age, 57.0 ± 11.9 years; women, 50.5%). Mean scores were C2-VBQ, 2.37 ± 0.55; C5-VBQ, 2.36 ± 0.61; and T1-VBQ, 2.64 ± 0.68. The C-VBQ scores for the C2 level were significantly higher than those for the C3-C6 levels (3.18 ± 0.96 vs. 2.63 ± 0.77, P < 0.001), whereas the C7 level was found to have significantly lower C-VBQ scores (2.42 ± 0.78 vs. 2.63 ± 0.77, P = 0.04). The C2-VBQ (r = 0.63) score had the strongest correlation to the VBQ score, compared to C5-VBQ (r = 0.41) and T1-VBQ (r = 0.43) (P < 0.001). CONCLUSIONS: This study demonstrates that the C2-VBQ had the strongest correlation to the lumbar VBQ score among all C-VBQ scores.