Biomechanical Analysis of Pedicle Screw Reinsertion Along the Same Trajectory in a Validated 3D-Printed Synthetic Bone Model.

OBJECTIVE: To investigate the biomechanical properties of pedicle screw reinsertion along the same trajectory in a previously validated synthetic bone model. METHODS: Twenty identical acrylonitrile butadiene styrene models of lumbar vertebrae were three-dimensional-printed. Screws were placed in the standard fashion into each pedicle. Models were separated into 2 equal groups, control and experimental. Experimental group screws were completely removed from their testing block and reinserted once. All screws in both groups were then forcibly removed. Continuous torque monitoring was collected on screw insertion torque (IT), removal torque, and reinsertion torque. Pullout strength (PO), screw stiffness (STI), and strain energy (STR) were calculated. RESULTS: There was no significant difference between control and experimental groups for PO (P = 0.26), STI (P = 0.55), STR (P = 0.50), or IT (P = 0.24). There was a significant decrease in reinsertion torque (54.5 N-cm ± 8.2 N-cm) from control IT (62.9 N-cm ± 8.4 N-cm, P = 0.045) and experimental IT (67.5 N-cm ± 7.6 N-cm, P = 0.0026). Strong correlations (Pearson's r > 0.80) were seen between control IT against STR and PO, between each of the experimental torque measurements, and between experimental PO and STI. CONCLUSIONS: Despite a significant decrease in insertion torque, there is no significant loss of pedicle screw performance when a screw is removed and reinserted along the same trajectory.

Comparison of transforaminal and posterior lumbar interbody fusion outcomes in patients receiving a novel allograft versus rhBMP-2: a radiographic and patient-reported outcomes analysis.

OBJECTIVE: Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been demonstrated to achieve the highest rates of arthrodesis in multilevel lumbar fusion but is also associated with possible perioperative morbidity. A novel allograft (OSTEOAMP) is a differentiated allograft that retains growth factors supporting bone healing. The authors sought to compare the clinical and radiographic outcomes of rhBMP-2 and the novel allograft in lumbar interbody arthrodesis to determine if the latter may be a safer and equally effective alternative to rhBMP-2 for single- and multilevel posterior or transforaminal lumbar interbody fusion (PLIF or TLIF). METHODS: Patients who underwent single- or multilevel TLIF or PLIF using either OSTEOAMP or rhBMP-2 at the authors' institution over a 2-year period were prospectively followed for 12 months. Healthcare utilization, safety measures, patient satisfaction, physical disability (measured on the Oswestry Disability Index [ODI]), back and leg pain (on the numeric rating scale [NRS]), quality of life (on the EQ-5D scale), and return to work (RTW) were prospectively recorded. For purposes of this study, this consecutive series was retrospectively analyzed and pseudarthrosis rates were assessed at 2 years of follow-up. All patients (100%) had both 12-month patient-reported outcome follow-up and 24-month clinical and radiographic follow-up. RESULTS: One thousand one hundred fifty-four patients (654 treated with OSTEOAMP, 500 with rhBMP-2) were prospectively enrolled in the institutional registry. After propensity score matching, there were no significant baseline differences between 330 novel allograft and 330 rhBMP-2 cases. Perioperative morbidity and 90-day hospital readmission (3.3% vs 2.4%, p = 0.485) did not significantly differ between the novel allograft and the rhBMP-2 cases. At the 2-year follow-up, symptomatic pseudarthrosis requiring revision surgery occurred in 8 patients (2.4%) with OSTEOAMP and 6 patients (1.8%) with rhBMP-2 (p = 0.589). The overall fusion rate at 2 years was similar between groups (p = 0.213). Both groups showed significant and equivalent improvement in patient-reported outcome measures (PROMs) from baseline to 12-month follow-up, with no significant difference in 1-year mean NRS leg pain score (2.5 vs 2.7), ODI (25 vs 26), quality-adjusted life years (0.73 vs 0.73), satisfaction (83% vs 80%), or RTW (6.6 vs 7 weeks). CONCLUSIONS: In the authors' institutional experience, OSTEOAMP is a clinically viable substitute for rhBMP-2 for single- and multilevel lumbar fusion. This novel allograft provides clinically effective arthrodesis and improvements in PROMs comparable to rhBMP-2 with a similar safety profile. Additional indications and outcome assessment in longitudinal studies are needed to further characterize this allogeneic graft.

Mental health comorbidities in workers' compensation patients and the effect on pain, disability, quality of life, and return to work after lumbar spine surgery.

OBJECTIVE: The impact of mental health comorbidities on outcomes after lumbar spine surgery in workers' compensation (WC) patients has not been robustly explored. The goal of this study was to examine the impact of mental health comorbidities on pain, disability, quality of life, and return to work after lumbar spine surgery in WC patients. METHODS: A nationwide, prospective surgical outcomes registry (National Neurosurgery Quality Outcomes Database [N2QOD]) was queried for all patients who underwent 1- to 4-level lumbar decompression and/or fusion from 2012 to 2021. Patients were stratified on the basis of compensation status into non-WC (25,507) and WC (1018) cohorts. Baseline demographic data, perioperative safety data, and patient-reported outcome measures were compared between groups. The WC cohort was further subdivided on the basis of mental health status into patients with anxiety and depression (n = 107) and those without anxiety and depression (n = 911). Propensity matching was used to generate parity between these subgroups, generating 214 patients (107 pairs) for analysis. Perioperative safety, facility utilization, 1-year patient-reported outcomes (back and leg pain, disability, and quality of life), and return to work were measured as a function of WC and mental health comorbidity status. RESULTS: A total of 26,525 patients (25,507 non-WC and 1018 WC) who underwent 1- to 4-level lumbar spine surgery were reviewed. WC patients were younger, healthier (lower American Society of Anesthesiologists class), more likely to be minorities, less educated, and more likely to smoke and had greater baseline back pain, disability, and quality of life compared to non-WC patients. The prevalence of anxiety and depression was similar between groups (11%). WC patients had worse outcomes for all measures and lower rates of return to work compared to non-WC patients. WC patients with anxiety and depression demonstrated even greater disparities in all outcomes. After propensity matching, WC patients with anxiety and depression continued to demonstrate significantly worse outcomes in comparison to WC patients without anxiety and depression. CONCLUSIONS: Disparities in outcomes after lumbar spine surgery in WC patients are exacerbated in patients with anxiety and depression. WC patients with mental health comorbidities receive the least benefit from lumbar spine surgery and may represent the most vulnerable subset of patients with spine pathology. Addressing mental health comorbidities preoperatively may represent an opportunity for valuable resource allocation and surgical optimization in the WC population.

Patent bibliometrics in spinal deformity: the first bibliometric analysis of spinal deformity's technological literature.

PURPOSE: Bibliometric analyses have gained popularity for studying scientific literature, but their application to evaluate technological literature (patents) remains unexplored. We conducted a bibliometric analysis on the top 100 most-cited patents in scoliosis surgery. METHODS: Multiple databases were queried using The Lens to identify the top 100 scoliosis surgery patents, which were selected based on forward patent citations. These patents were then categorized into 8 groups based on technological descriptors and assessed based on various factors including earliest priority date, year issued, and expiration status. RESULTS: The top 100 most-cited patents included technology underlying anterolateral tethering and distraction systems (n = 11), posterior tethering and distraction systems (n = 23), posterior segmental bone anchor and rod engagement systems (n = 29), interbody devices (n = 10), biological and electrophysiological agents for scoliosis treatment and/or improved arthrodesis (n = 8), intraoperative arthroplasty devices (n = 5), orthotic devices (n = 12), and implantable devices for non-invasive, postoperative alterations of skeletal alignment (n = 2). Seventy-five patents were expired, 21 are still active, and 4 were listed as inactive. The late 1970s and early 2000s saw increased numbers of patent filings. Demonstrated trends showed no meaningful correlation between patent rank and earliest priority date (linear trendline y = 0.2648x - 477.27; R2 = 0.0114), while a very strong correlation was found between patent rank and citations per year (power trendline y = 118.82x--0.83; R2 = 0.8983). CONCLUSION: Patent bibliometric analyses in the field of spinal deformity surgery provide a means to assess past advancements, better understand what it takes to make a difference in the field, and to potentially facilitate the development of innovative technologies in the future. The method described is a reliable and reproducible technique for evaluating technological literature in our field.

Survey of United States neurosurgeons on firearm injury prevention.

OBJECTIVE: Firearm-related injuries and deaths are an endemic problem in the US, posing a burden on the healthcare system with significant social and economic consequences. As front-line care providers for these patients, neurosurgeons are both knowledgeable about these injuries and credible messengers in the public discussion of ways to reduce firearm injuries. The purpose of this study was to explore US-based neurosurgeons' views and behaviors regarding firearms to understand and define a potential role for neurosurgical organizations in advocacy efforts to reduce firearm death and injuries. METHODS: The authors conducted an anonymous survey of US neurosurgeons using the American Association of Neurological Surgeons (AANS) member database from April to June 2023. The 22-question survey included questions related to firearm ownership, personal views on firearms, and support for both general and policy-specific advocacy efforts to reduce firearm deaths and injuries. RESULTS: The survey response rate was 20.7%, with 1568 of the 7587 members invited completing the survey. The survey completion rate was 93.4%, with 1465 of the 1568 surveys completed and included in this analysis. The majority of respondents were male (raw: 81.7%; weighted 81.1%), White (raw: 69.7%; weighted 70.2%), and older than 50 years (raw: 56.2%; weighted: 54%). Most respondents reported treating patients with firearm injuries (raw: 83.3%; weighted: 82%), 85.5% (weighted: 85.1%) had used a firearm, and 42.4% (weighted: 41.5%) reported owning a firearm. Overall, 78.8% (weighted: 78.7%) of respondents felt that organized neurosurgery should participate in advocacy efforts. When examining individual policies, those that restrict the acquisition of firearms garnered the support of at least 65% of respondents, while nonrestrictive policies were supported by more than 75% of respondents. Free-text responses provided insight into both motivations for and objections to organizational advocacy. CONCLUSIONS: The majority of US-based neurosurgeons support involvement in advocacy efforts to reduce firearm deaths and injuries. Themes expressed by members both supporting and objecting to advocacy provide insight into approaches that could ensure broad support. Neurosurgical organizations such as the AANS and Congress of Neurological Surgeons may use the results of this survey to make informed decisions regarding involvement in advocacy efforts on behalf of their membership to lessen the burden of firearm injury in the US.

Effect of workers' compensation status on pain, disability, quality of life, and return to work after anterior cervical discectomy and fusion: a 1-year propensity score-matched analysis.

OBJECTIVE: Patients with workers' compensation (WC) claims are reported to demonstrate poorer surgical outcomes after lumbar spine surgery. However, outcomes after anterior cervical discectomy and fusion (ACDF) in WC patients remain debatable. The authors aimed to compare outcomes between a propensity score-matched population of WC and non-WC patients who underwent ACDF. METHODS: Patients who underwent 1- to 4-level ACDF were retrospectively reviewed from the prospectively maintained Quality Outcomes Database (QOD). After propensity score matching, 1-year patient satisfaction, physical disability (Neck Disability Index [NDI]), pain (visual analog scale [VAS]), EQ-5D, and return to work were compared between WC and non-WC cohorts. RESULTS: A total of 9957 patients were included (9610 non-WC and 347 WC patients). Patients in the WC cohort were significantly younger (50 ± 9.1 vs 56 ± 11.4 years, p < 0.001), less educated, and were more frequently male, non-Caucasian, and active smokers (29.1% vs 18.1%, p < 0.001), with greater baseline VAS and NDI scores and poorer quality of life (p < 0.001). One-year postoperative improvements in VAS, NDI, EQ-5D, and return-to-work rates and satisfaction were all significantly worse for WC compared with non-WC patients. After adjusting for baseline differences via propensity score matching, WC versus non-WC patients continued to demonstrate worse 3- and 12-month VAS neck pain and NDI (p = 0.010), satisfaction (χ2 = 4.03, p = 0.045), and delayed return to work (9.3 vs 5.7 weeks, p < 0.001). CONCLUSIONS: WC status was associated with greater 1-year residual disability and axial pain along with delayed return to work, without any difference in quality of life despite having fewer comorbidities and being a younger population. Further studies are needed to determine the societal impact that WC claims have on healthcare delivery in the setting of ACDF.

Minimally Invasive Transforaminal Lumbar Interbody Fusion in the Ambulatory Surgery Center Versus Inpatient Setting: A 1-Year Comparative Effectiveness Analysis.

BACKGROUND: Ambulatory surgery centers (ASCs) have emerged as an alternative setting for surgical care as part of the national effort to lower health care costs. The literature regarding the safety of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) in the ASC setting is limited to few small case series. OBJECTIVE: To assess the safety and efficacy of MIS TLIF performed in the ASC vs inpatient hospital setting. METHODS: A total of 775 patients prospectively enrolled in the Quality Outcomes Database undergoing single-level MIS TLIF at a single ASC (100) or the inpatient hospital setting (675) were compared. Propensity matching generated 200 patients for analysis (100 per cohort). Demographic data, resource utilization, patient-reported outcome measures (PROMs), and patient satisfaction were assessed. RESULTS: There were no significant differences regarding baseline demographic data, clinical history, or comorbidities after propensity matching. Only 1 patient required inpatient transfer from the ASC because of intractable pain. All other patients were discharged home within 23 hours of surgery. The rates of 90-day readmission (2.0%) and reoperation (0%) were equivalent between groups. Both groups experienced significant improvements in all PROMs (Oswestry Disability Index, EuroQol-5D, back pain, and leg pain) at 3 months that were maintained at 1 year. PROMs did not differ between groups at any time point. Patient satisfaction was similar between groups at 3 and 12 months after surgery. CONCLUSION: In carefully selected patients, MIS TLIF may be performed safely in the ASC setting with no statistically significant difference in safety or efficacy in comparison with the inpatient setting.

Effect of workers' compensation status on pain, disability, quality of life, and return to work after lumbar spine surgery: a 1-year propensity-matched analysis.

OBJECTIVE: Workers' compensation (WC) and litigation have been shown to adversely impact prognoses in a vast range of health conditions. Low-back pain is currently the most frequent reason for WC claims. The objective of this study was to conduct the largest propensity-matched comparison of outcomes between patients with WC and non-WC status who underwent lumbar spinal decompression with and without fusion. METHODS: Complete data sets for patients who underwent 1- to 4-level lumbar spinal fusion or decompression alone were retrospectively retrieved from the Quality Outcomes Database (QOD), which included 1-year patient-reported outcomes from more than 200 hospital systems collected from 2012 to 2021. Population demographics, perioperative safety, facility utilization, patient satisfaction, disability, pain, EQ-5D quality of life, and return to work (RTW) rates were compared between cohorts for both subgroups. Statistical significance was set at p < 0.05. RESULTS: There were 29,652 patients included in the study. Laminectomy was performed in 16,939 with non-WC status and in 615 with WC, whereas fusion was performed in 11,767 with non-WC status and in 331 with WC. WC patients were more frequently male, a minority race, younger, less educated, more frequently a smoker, had a healthier American Society of Anesthesiologists grade, and with greater baseline visual analog scale (VAS) and Oswestry Disability Index (ODI) scores (p < 0.001). One-year postoperative improvements in VAS, ODI, quality-adjusted life years (QALYs), RTW rates, and satisfaction were all significantly worse for WC versus non-WC patients for both procedures. After adjusting for baseline differences via propensity matching, WC versus non-WC patients continued to demonstrate worse 3- and 12-month VAS and ODI scores, reduced 12-month QALY gain, and delayed RTW after both procedure types. CONCLUSIONS: WC status was associated with significantly greater residual disability and pain postoperatively, a lower quality of life, and delayed RTW. Utilizing resources to identify the negative influences on outcomes for WC patients may be valuable in preoperative optimization and could yield better outcomes in these patients.

Anterior Cervical Discectomy and Fusion Versus Microendoscopic Posterior Cervical Foraminotomy for Unilateral Cervical Radiculopathy: A 1-Year Cost-Utility Analysis.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) and posterior cervical foraminotomy (PCF) are the most common surgical approaches for medically refractory cervical radiculopathy. Rigorous cost-effectiveness studies comparing ACDF and PCF are lacking. OBJECTIVE: To assess the cost-utility of ACDF vs PCF performed in the ambulatory surgery center setting for Medicare and privately insured patients at 1-year follow-up. METHODS: A total of 323 patients who underwent 1-level ACDF (201) or PCF (122) at a single ambulatory surgery center were compared. Propensity matching generated 110 pairs (220 patients) for analysis. Demographic data, resource utilization, patient-reported outcome measures, and quality-adjusted life-years were assessed. Direct costs (1-year resource use × unit costs based on Medicare national allowable payment amounts) and indirect costs (missed workdays × average US daily wage) were recorded. Incremental cost-effectiveness ratios were calculated. RESULTS: Perioperative safety, 90-day readmission, and 1-year reoperation rates were similar between groups. Both groups experienced significant improvements in all patient-reported outcome measures at 3 months that was maintained at 12 months. The ACDF cohort had a significantly higher preoperative Neck Disability Index and a significantly greater improvement in health-state utility (ie, quality-adjusted life-years gained) at 12 months. ACDF was associated with significantly higher total costs at 1 year for both Medicare ($11 744) and privately insured ($21 228) patients. The incremental cost-effectiveness ratio for ACDF was $184 654 and $333 774 for Medicare and privately insured patients, respectively, reflecting poor cost-utility. CONCLUSION: Single-level ACDF may not be cost-effective in comparison with PCF for surgical management of unilateral cervical radiculopathy.

Anterior Cervical Discectomy and Fusion in the Ambulatory Surgery Center Versus Inpatient Setting: One-Year Cost-Utility Analysis.

STUDY DESIGN: Retrospective analysis of prospectively collected data. OBJECTIVE: Assess the cost-utility of anterior cervical discectomy and fusion (ACDF) performed in the ambulatory surgery center (ASC) versus inpatient hospital setting for Medicare and privately insured patients at one-year follow-up. SUMMARY OF BACKGROUND DATA: Outpatient ACDF has gained popularity due to improved safety and reduced costs. Formal cost-utility studies for ambulatory versus inpatient ACDF are lacking, precluding an accurate assessment of cost-effectiveness. MATERIALS AND METHODS: A total of 6504 patients enrolled in the Quality Outcomes Database (QOD) undergoing one-level to two-level ACDF at a single ASC (520) or the inpatient hospital setting (5984) were compared. Propensity matching generated 748 patients for analysis (374 per cohort). Demographic data, resource utilization, patient-reported outcome measures, and quality-adjusted life-years (QALYs) were assessed. Direct costs (1-year resource use×unit costs based on Medicare national allowable payment amounts) and indirect costs (missed workdays×average US daily wage) were recorded. Incremental cost-effectiveness ratios were calculated. RESULTS: Complication rates and improvements in patient-reported outcome measures and QALYs were similar between groups. Ambulatory ACDF was associated with significantly lower total costs at 1 year for Medicare ($5879.46) and privately insured ($12,873.97) patients, respectively. The incremental cost-effectiveness ratios for inpatient ACDF was $3,674,662 and $8,046,231 for Medicare and privately insured patients, respectively, reflecting unacceptably poor cost-utility. CONCLUSION: Inpatient ACDF is associated with significant increases in total costs compared to the ASC setting without a safety, outcome, or QALY benefit. The ASC setting is a dominant option from a health economy perspective for first-time one-l to two-level ACDF in select patients compared to the inpatient hospital setting.

Review: Patent Bibliometrics in Cranial Neurosurgery: The First Bibliometric Analysis of Neurosurgery's Technological Literature.

BACKGROUND: Bibliometric analyses of the scientific literature have grown increasingly popular in the past few decades. However, patent bibliometric studies, evaluation of technological literature, have not yet been applied in neurosurgery. OBJECTIVE: To perform a pilot patent bibliometric analysis of the top 100 most cited patents in cranial neurosurgery. METHODS: The Lens was used to query multiple databases, to select the top 100 cranial neurosurgical patents based upon forward patent citations. These were organized into 9 categories based on technological descriptors and were evaluated based on the earliest priority date, year issued, and expiration status, among others. RESULTS: The top 100 most cited patents included technology underlying 3D navigation (n = 31), pharmacology and implants (n = 20), vascular occlusion (n = 5), craniotomy closure (n = 9), focal lesioning and tissue resection (n = 8), brain and systemic cooling (n = 5), neuroendoscopy (n = 8), neuromonitoring and stimulation (6), and technologies improving surgeon performance (n = 8). Ninety-six patents were filed in the United States, 72 were expired, 19 are still active, and 9 were listed as inactive. The highest number of patents was applied for from the mid-1990s to the mid-2000s. Demonstrated trends showed no meaningful correlation between patent rank and earliest priority date (linear trendline y = 0.7107 x -1367.5; R2 = 0.0671), while a very strong correlation was found between patent rank and citations per year (power trendline y = 127.93 x -1.094; R2 = 0.8579). CONCLUSIONS: Patent bibliometrics allow evaluation of neurosurgical advancements from the past and enable subsequent development of cutting-edge technology in the future. The described method is a reproducible and reliable technique for evaluating our field's patent literature.

Technical Feasibility of Subaxial Cervical Pedicle Screws for Distal Anchoring of Occipitocervical Fixation Constructs in the Mid-Cervical Spine: Early Clinical Experience.

Occipitocervical fixation and fusion (OCF) is performed for patients who have destabilizing traumatic injuries or pathologies affecting the complex bony and ligamentous structures of the occipitoatlantal and atlantoaxial joint structures. Distal fixation failure and pseudoarthrosis are known risks of these constructs, especially for those constructs ending in the mid-cervical spine. We present the technical feasibility of using cervical pedicle screws (CPSs) as distal fixation anchors to strengthen OCF constructs ending in the mid-cervical spine and present a case series describing our early clinical experience with this technique. We used a freehand technique to place subaxial pedicle screws in the mid-cervical spine as the distal fixation point in OCF constructs. This technique involves performing a laminotomy to provide direct visualization of the pedicle borders to safely guide freehand pedicle screw placement. Our early clinical experience with this technique is presented. Three patients received OCF constructs ending in the mid-cervical subaxial spine between C3 and C6. CPSs were placed at the distal vertebra in each construct. Stable instrumentation and arthrodesis were confirmed postoperatively in all patients. This freehand technique uses direct visualization of the pedicle to aid in safe and accurate subaxial pedicle screw placement. CPS placement is clinically feasible and increases the robustness of OCF constructs in appropriately selected patients. Larger case series are needed to further validate the safety and effectiveness of this technique.

Hospital use following anterior cervical discectomy and fusion.

Most existing anterior cervical discectomy and fusion (ACDF) outcome studies omit emergency department (ED) use. To our knowledge, this study on ED use following ACDF surgery is the first to use a direct patient chart review and the first to include revision patients, 1-5 levels of ACDFs, and performance of corpectomy in the analysis. This study examines the frequency and basis of hospital service use within 30 days of ACDF surgery, specifically ED visits, hospital readmissions, and returns to the operating room. A retrospective chart review was performed for 1273 consecutive patients who underwent ACDF surgery at one institution from July 2013 to June 2016. Of the 1273 patients with ACDF, 97 (7.6%) presented to the ED within 30 days after surgery. Of 43 patients with revision ACDF, 9 (20.9%) returned to the ED, compared with 88 (7.2%) of 1230 patients with primary ACDF (P = 0.001). Of the 111 ED visits by 97 patients, 40 (36%) were for cervicalgia, 13 (12%) were for dysphagia, 8 (7%) were for trauma, 7 (6%) were for nausea, 4 (4%) were for medication refill, 3 (3%) were for dehiscence, 3 (3%) were for pneumonia, and 3 (3%) were for urinary tract infection. Of the ED presentations, 8 (7%) occurred during the first 2 days after surgery, and 46 (41%) occurred within the first postoperative week.

Vascularized Occipital Bone Grafting: Indications, Techniques, Clinical Outcomes, and Alternatives.

Successful arthrodesis at the craniocervical junction and atlantoaxial joint can be more challenging than in other segments of the cervical spine. Different techniques for spinal fixation in this region have been well described, along with auxiliary methods to improve fusion rates. The occipital vascularized bone graft is a novel technique that can be used to augment bony arthrodesis in the supra-axial cervical spine. It provides the benefits of a vascularized autologous graft, such as accelerated healing, earlier fusion, and increased strength. This technique can be learned with relative ease and may be particularly helpful in cases with high risk of nonunion or pseudoarthrosis in the upper cervical spine.

Vascularized Rib Bone Grafting: Indications, Techniques, and Clinical Outcomes.

Pseudarthrosis is a difficult complication often seen in patients with complex spinal pathology. To supplement existing neurosurgical approaches to cervicothoracic spinal instrumentation and fusion, novel vascularized rib bone grafts can be utilized in patients at high risk for failed spinal fusion. In this article, we discuss the indications, benefits, surgical technique, feasibility, and limitations of using rib vascularized rib bone grafts to augment spinal fusion.

Vascularized Bone Grafts in Spinal Reconstruction: An Overview of Nomenclature and Indications.

Several vascularized bone grafts (VBGs) have been introduced for reconstruction and augmenting fusion of the spine. The expanding use of VBGs in the field of spinoplastic reconstruction, however, has highlighted the need to clarify the nomenclature for bony reconstruction as well as establish the position of VBGs on the bony reconstructive algorithm. In the current literature, the terms "flap" and "graft" are often applied inconsistently when describing vascularized bone transfer. Such inconsistency creates barriers in communication between physicians, confusion in interpreting the existing studies, and difficulty in comparing surgical techniques. VBGs are defined as bone segments transferred on their corresponding muscular attachments without a named major feeding vessel. The bone is directly vascularized by the muscle attachments and unnamed periosteal feeding vessels. VBGs are best positioned as a separate entity in the bony reconstruction algorithm between nonvascularized bone grafts (N-VBGs) and bone flaps. VBGs offer numerous advantages as they supply fully vascularized bone to the recipient site without the microsurgical techniques or pedicle dissection required for raising bone flaps. Multiple VBGs have been introduced in recent years to optimize these benefits for spinoplastic reconstruction.

Subaxial Cervical Pedicle Screw Placement With Direct Visualization of Pedicle Borders: 2-Dimensional Operative Video.

Pedicle screws provide superior fixation of the subaxial cervical spine to other techniques. However, a high degree of accuracy is required for safe placement given the proximity of pedicles to critical neurovascular structures. A variety of techniques are described to maximize accuracy, including freehand, fluoroscopy-guided, and neuronavigation-based methods. We present a technique for the placement of pedicle screws in the subaxial cervical spine using direct visualization of the pedicle in a patient who required an occipito-cervical fusion construct in the setting of a C2 chordoma. A laminotomy or laminectomy is performed laterally to allow for visualization of the medial, superior, and inferior walls of the pedicle. The entry point for screw placement is determined based on pedicle anatomy and is typically 1 to 2 mm lateral to the midpoint of the lateral mass, just below the base of the superior articulating process. Screw trajectory is determined by visualizing the pedicle borders and is aimed at the junction of the medial pedicle wall, with the posterior vertebral body down the pedicle axis. Tactile feedback (loss of resistance) is used to assess for a breach while drilling. The cannulation is then tapped, and the screw is placed in a standard fashion. Direct visualization of pedicle anatomy can be a useful adjunct to guide the safe placement of subaxial pedicle screws when superior fixation is required or when normal anatomy is distorted. The technique may be combined with fluoroscopic or navigation-based techniques to provide real-time anatomic guidance during screw placement. The patient provided informed, written consent for this procedure before surgery. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Perioperative and swallowing outcomes in patients undergoing 4- and 5-level anterior cervical discectomy and fusion.

OBJECTIVE: Anterior cervical discectomy and fusion (ACDF) is a common and robust procedure performed on the cervical spine. Literature on ACDF for 4 or more segments is sparse. Increasing the number of operative levels increases surgical complexity, tissue retraction, and risks of complications, particularly dysphagia. The overall risks of these complications and rates of dysphagia are not well studied for surgery on 4 or more segments. In this study, the authors evaluated their institution's perioperative experience with 4- and 5-level ACDFs. METHODS: The authors retrospectively reviewed patients who underwent 4- or 5-level ACDF at their institution over a 6-year period (May 2013-May 2019). Patient demographics, perioperative complications, readmission rates, and swallowing outcomes were recorded. Outcomes were analyzed with a multivariate linear regression. RESULTS: A total of 174 patients were included (167 had 4-level and 7 had 5-level ACDFs). The average age was 60.6 years, and 54.0% of patients (n = 94) were men. A corpectomy was performed in 12.6% of patients (n = 22). After surgery, 56.9% of patients (n = 99) experienced dysphagia. The percentage of patients with dysphagia decreased to 22.8% (37/162) at 30 days, 12.9% (17/132) at 90 days, and 6.3% (5/79) and 2.8% (1/36) at 1 and 2 years, respectively. Dysphagia was more likely at 90 days postoperatively in patients with gastroesophageal reflux (OR 4.4 [95% CI 1.5-12.8], p = 0.008), and the mean (± SD) lordosis change was greater in patients with dysphagia than those without at 90 days (19.8° ± 13.3° vs 9.1° ± 10.2°, p = 0.003). Dysphagia occurrence did not differ with operative implants, including graft and interbody type. The mean length of time to solid food intake was 2.4 ± 2.1 days. Patients treated with dexamethasone were more likely to achieve solid food intake prior to discharge (OR 4.0 [95% CI 1.5-10.6], p = 0.004). Postsurgery, 5.2% of patients (n = 9) required a feeding tube due to severe approach-related dysphagia. Other perioperative complication rates were uniformly low. Overall, 8.6% of patients (n = 15) returned to the emergency department within 30 days and 2.9% (n = 5) required readmission, whereas 1.1% (n = 2) required unplanned return to surgery within 30 days. CONCLUSIONS: This is the largest series of patients undergoing 4- and 5-level ACDFs reported to date. This procedure was performed safely with minimal intraoperative complications. More than half of the patients experienced in-hospital dysphagia, which increased their overall length of stay, but dysphagia decreased over time.

Vascularized Bone Grafts for Spinal Fusion-Part 3: The Occiput.

BACKGROUND: Obtaining successful arthrodesis at the craniocervical junction and atlantoaxial joint can be more challenging than in other segments of the cervical spine. This challenge stems from the relatively hypermobile joints between the occipital condyles, the motion that occurs at C1 and C2, as well as the paucity of dorsal bony surfaces for posterior arthrodesis. While multiple different techniques for spinal fixation in this region have been well described, there has been little investigation into auxiliary methods to improve fusion rates. OBJECTIVE: To describe the use of an occipital bone graft to augment bony arthrodesis in the supraaxial cervical spine using a multidisciplinary approach. METHODS: We review the technique for harvesting and placing a vascularized occipital bone graft in 2 patients undergoing revision surgery at the craniocervical junction. RESULTS: The differentiation from nonvascularized bone graft, either allograft or autograft, to a bone graft using vascularized tissue is a key principle of this technique. It has been well established that vascularized bone heals and fuses in the spine better than structural autogenous grafts. However, the morbidity and added operative time of harvesting a vascularized flap, such as from the fibula or rib, precludes its utility in most degenerative spine surgeries. CONCLUSION: By adapting the standard neurosurgical procedure for a suboccipital craniectomy and utilizing the tenets of flap-based reconstructive surgery to maintain the periosteal and muscular blood supply, we describe the feasibility of using a vascularized and pedicled occipital bone graft to augment instrumented upper cervical spinal fusion. The use of this vascularized bone graft may increase fusion rates in complex spine surgeries.

Vascularized Bone Grafts for Spinal Fusion-Part 2: The Rib.

BACKGROUND: Pseudoarthrosis, or failure to achieve bony union, is a well-known complication of spinal fusion operations. Rates range from 5% to 40% and are influenced by both patient and technical factors. Patients who do not achieve complete fusion may experience a return or worsening of their preoperative pain. For patients with complicated pathologies, vascularized bone grafts (VBGs) have been shown to provide better outcomes than nonvascularized bone grafts (N-VBGs). OBJECTIVE: To enhance an instrumented spinal fusion by the innovative technique presented herein that utilizes a rotated, pedicled VBG from the left eighth rib under the paraspinous musculature into the midlumbar posterolateral gutter. METHODS: For posterior approaches, the rib can be easily accessed and rotated into the appropriate strut position. The rib is dissected out, identifying and preserving the neurovascular bundle medially. The rib is then tunneled medially and appropriately positioned as the spinal graft, with the curve providing anatomic kyphosis or lordosis, depending on the surgical location. It is then successfully fixated with plates and spinal screws. RESULTS: In our limited experience to date, vascularized rib grafting procedures augment fusion and reduce operating room time and bleeding compared to free flap procedures. No patients have experienced complications related to these grafts. CONCLUSION: Pedicled vascularized rib grafts can be utilized to provide the advantages of a vascularized bone flap in complicated pathologies requiring spinal fusion as far as the L2-L3 level, without the morbidity associated with free tissue transfer.