Anterior occipital condyle screw placement through the endonasal corridor: proof of concept study with cadaveric analysis.

PURPOSE: Odontoidectomy for ventral compressive pathology may result in O-C1 and/or C1-2 instability. Same-stage endonasal C1-2 spinal fusion has been advocated to eliminate risks associated with separate-stage posterior approaches. While endonasal methods for C1 instrumentation and C1-2 trans-articular stabilization exist, no hypothetical construct for endonasal occipital instrumentation has been validated. We provide an anatomic description of anterior occipital condyle (AOC) screw endonasal placement as proof-of-concept for endonasal craniocervical stabilization. METHODS: Eight adult, injected cadaveric heads were studied for placing 16 AOC screws endonasally. Thin-cut CT was used for registration. After turning a standard inferior U-shaped nasopharyngeal flap endonasally, 4 mm × 22 mm AOC screws were placed with a 0° driver using neuronavigation. Post-placement CT scans were obtained to determine: site-of-entry, measured from the endonasal projection of the medial O-C1 joint; screw angulation in sagittal and axial planes, proximity to critical structures. RESULTS: Average site-of-entry was 6.88 mm lateral and 9.74 mm rostral to the medial O-C1 joint. Average angulation in the sagittal plane was 0.16° inferior to the palatal line. Average angulation in the axial plane was 23.97° lateral to midline. Average minimum screw distances from the jugular bulb and hypoglossal canal were 4.80 mm and 1.55 mm. CONCLUSION: Endonasal placement of AOC screws is feasible using a 0° driver. Our measurements provide useful parameters to guide optimal placement. Given proximity of hypoglossal canal and jugular bulb, neuronavigation is recommended. Biomechanical studies will ultimately be necessary to evaluate the strength of AOC screws with plate-screw constructs utilizing endonasal C1 lateral mass or C1-2 trans-articular screws as inferior fixation points.

Generation of Cross-Specialty Consensus Statements on Soft Tissue Management via a Modified Delphi Method.

BACKGROUND: Soft tissue management (STM) training programs for surgeons are largely tradition based, and substantial differences exist among different surgical specialties. The lack of comprehensive and systematic clinical evidence on how surgical techniques and implants affect soft tissue healing makes it difficult to develop evidence-based curricula. As a curriculum development group (CDG), we set out to find common grounds in the form of a set of consensus statements to serve as the basis for surgical soft tissue education. METHODS: Following a backward planning process and Kern's six-step approach, the group selected 13 topics to build a cross-specialty STM curriculum. A set of statements based on the curriculum topics were generated by the CDG through discussions and a literature review of three topics. A modified Delphi process including one round of pilot voting through a face-to-face CDG meeting and two rounds of web-based survey involving 22 panelists were utilized for the generation of consensus statements. RESULTS: Seventy-one statements were evaluated, and 56 statements reached the 80% consensus for "can be taught as is." CONCLUSIONS: Using a modified Delphi method, a set of cross-specialty consensus statements on soft tissue management were generated. These consensus statements can be used as a foundation for multi-specialty surgical education. Similar methods that combine expert experience and clinical evidence can be used to develop specialty-specific consensus on soft tissue handling.

How Many Steps Per Day During the Early Postoperative Period are Associated With Patient-Reported Outcomes of Disability, Pain, and Opioid Use After Lumbar Spine Surgery?

OBJECTIVE: To investigate whether early postoperative walking is associated with "best outcome" and no opioid use at 1 year after lumbar spine surgery and establish a threshold for steps/day to inform clinical practice. DESIGN: Secondary analysis from randomized controlled trial. SETTING: Two academic medical centers in the United States. PARTICIPANTS: We enrolled 248 participants undergoing surgery for a degenerative lumbar spine condition (N=248). A total of 212 participants (mean age, 62.8±11.4y, 53.3% female) had valid walking data at baseline. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Disability (Oswestry Disability Index), back and leg pain (Brief Pain Inventory), and opioid use (yes vs no) were assessed at baseline and 1 year after surgery. "Best outcome" was defined as Oswestry Disability Index ≤20, back pain ≤2, and leg pain ≤2. Steps/day (walking) was assessed with an accelerometer worn for at least 3 days and 10 h/d at 6 weeks after spine surgery, which was considered as study baseline. Separate multivariable logistic regression analyses were conducted to determine the association between steps/day at 6 weeks and "best outcome" and no opioid use at 1-year. Receiver operating characteristic curves identified a steps/day threshold for achieving outcomes. RESULTS: Each additional 1000 steps/d at 6 weeks after spine surgery was associated with 41% higher odds of achieving "best outcome" (95% confidence interval [CI], 1.15-1.74) and 38% higher odds of no opioid use (95% CI, 1.09-1.76) at 1 year. Walking ≥3500 steps/d was associated with 3.75 times the odds (95% CI, 1.56-9.02) of achieving "best outcome" and 2.37 times the odds (95% CI, 1.07-5.24) of not using opioids. CONCLUSIONS: Walking early after surgery may optimize patient-reported outcomes after lumbar spine surgery. A 3500 steps/d threshold may serve as an initial recommendation during early postoperative counseling.

Role of psychosocial factors on the effect of physical activity on physical function in patients after lumbar spine surgery.

BACKGROUND: The purpose of this study was to investigate the longitudinal postoperative relationship between physical activity, psychosocial factors, and physical function in patients undergoing lumbar spine surgery. METHODS: We enrolled 248 participants undergoing surgery for a degenerative lumbar spine condition. Physical activity was measured using a triaxial accelerometer (Actigraph GT3X) at 6-weeks (6wk), 6-months (6M), 12-months (12M) and 24-months (24M) following spine surgery. Physical function (computerized adaptive test domain version of Patient-Reported Outcomes Measurement Information System) and psychosocial factors (pain self-efficacy, depression and fear of movement) were assessed at preoperative visit and 6wk, 6M, 12M and 24M after surgery. Structural equation modeling (SEM) techniques were utilized to analyze data, and results are represented as standardized regression weights (SRW). Overall SRW were computed across five imputed datasets to account for missing data. The mediation effect of each psychosocial factor on the effect of physical activity on physical function were computed [(SRW for effect of activity on psychosocial factor X SRW for effect of psychosocial factor on function) ÷ SRW for effect of activity on function]. Each SEM model was tested for model fit by assessing established fit indexes. RESULTS: The overall effect of steps per day on physical function (SRW ranged from 0.08 to 0.19, p<0.05) was stronger compared to the overall effect of physical function on steps per day (SRW ranged from non-existent to 0.14, p<0.01 to 0.3). The effect of steps per day on physical function and function on steps per day remained consistent after accounting for psychosocial factors in each of the mediation models. Depression and fear of movement at 6M mediated 3.4% and 5.4% of the effect of steps per day at 6wk on physical function at 12M, respectively. Pain self-efficacy was not a statistically significant mediator. CONCLUSIONS: The findings of this study suggest that the relationship between physical activity and physical function is stronger than the relationship of function to activity. However, future research is needed to examine whether promoting physical activity during the early postoperative period may result in improvement of long-term physical function. Since depression and fear of movement had a very small mediating effect, additional work is needed to investigate other potential mediating factors such as pain catastrophizing, resilience and exercise self-efficacy.

Early postoperative physical activity and function: a descriptive case series study of 53 patients after lumbar spine surgery.

BACKGROUND: The purpose of this prospective case series study was to compare changes in early postoperative physical activity and physical function between 6 weeks and 3 and 6 months after lumbar spine surgery. METHODS: Fifty-three patients (mean [95% confidence interval; CI] age = 59.2 [56.2, 62.3] years, 64% female) who underwent spine surgery for a degenerative lumbar condition were assessed at 6 weeks and 3- and 6-months after surgery. The outcomes were objectively-measured physical activity (accelerometry) and patient-reported and objective physical function. Physical activity was assessed using mean steps/day and time spent in moderate to vigorous physical activity (MVPA) over a week. Physical function measures included Oswestry Disability Index (ODI), 12-item Short Form Health Survey (SF-12), Timed Up and Go (TUG), and 10-Meter Walk (10 MW). We compared changes over time in physical activity and function using generalized estimating equations with robust estimator and first-order autoregressive covariance structure. Proportion of patients who engaged in meaningful physical activity (e.g., walked at least 4400 and 6000 steps/day or engaged in at least 150 min/week in MVPA) and achieved clinically meaningful changes in physical function were compared at 3 and 6 months. RESULTS: After surgery, 72% of patients initiated physical therapy (mean [95%CI] sessions =8.5 [6.6, 10.4]) between 6 weeks and 3 months. Compared to 6 weeks post-surgery, no change in steps/day or time in MVPA/week was observed at 3 or 6 months. From 21 to 23% and 9 to 11% of participants walked at least 4400 and 6000 steps/day at 3 and 6 months, respectively, while none of the participants spent at least 150 min/week in MVPA at these same time points. Significant improvements were observed on ODI, SF-12, TUG and 10 MW (p <  0.05), with over 43 to 68% and 62 to 87% achieving clinically meaningful improvements on these measures at 3 and 6 months, respectively. CONCLUSION: Limited improvement was observed in objectively-measured physical activity from 6 weeks to 6 months after spine surgery, despite moderate to large function gains. Early postoperative physical therapy interventions targeting physical activity may be needed.

Examining the Emergency Medical Treatment and Active Labor Act: impact on telemedicine for neurotrauma.

The Emergency Medical Treatment and Active Labor Act (EMTALA) protects patient access to emergency medical treatment regardless of insurance or socioeconomic status. A significant result of the COVID-19 pandemic has been the rapid acceleration in the adoption of telemedicine services across many facets of healthcare. However, very little literature exists regarding the use of telemedicine in the context of EMTALA. This work aimed to evaluate the potential to expand the usage of telemedicine services for neurotrauma to reduce transfer rates, minimize movement of patients across borders, and alleviate the burden on tertiary care hospitals involved in the care of patients with COVID-19 during a global pandemic. In this paper, the authors outline EMTALA provisions, provide examples of EMTALA violations involving neurosurgical care, and propose guidelines for the creation of telemedicine protocols between referring and consulting institutions.

Demographics, presentation and symptoms of patients with Klippel-Feil syndrome: analysis of a global patient-reported registry.

INTRODUCTION: Klippel-Feil syndrome (KFS) occurs due to failure of vertebral segmentation during development. Minimal research has been done to understand the prevalence of associated symptoms. Here, we report one of the largest collections of KFS patient data. METHODS: Data were obtained from the CoRDS registry. Participants with cervical fusions were categorized into Type I, II, or III based on the Samartzis criteria. Symptoms and comorbidities were assessed against type and location of fusion. RESULTS: Seventy-five patients (60F/14M/1 unknown) were identified and classified as: Type I, n = 21(28%); Type II, n = 15(20%); Type III, n = 39(52%). Cervical fusion by level were: OC-C1, n = 17(22.7%), C1-C2, n = 24(32%); C2-C3, n = 42(56%); C3-C4, n = 30(40%); C4-C5, n = 42(56%); C5-C6, n = 32(42.7%); C6-C7, n = 25(33.3%); C7-T1, n = 13(17.3%). 94.6% of patients reported current symptoms and the average age when symptoms began and worsened were 17.5 (± 13.4) and 27.6 (± 15.3), respectively. Patients reported to have a high number of comorbidities including spinal, neurological and others, a high frequency of general symptoms (e.g., fatigue, dizziness) and chronic symptoms (limited range of neck motion [LROM], neck/spine muscles soreness). Sprengel deformity was reported in 26.7%. Most patients reported having received medication and invasive/non-invasive procedures. Multilevel fusions (Samartzis II/III) were significantly associated with dizziness (p = 0.040), the presence of LROM (p = 0.022), and Sprengel deformity (p = 0.036). CONCLUSION: KFS is associated with a number of musculoskeletal and neurological symptoms. Fusions are more prevalent toward the center of the cervical region, and less common at the occipital/thoracic junction. Associated comorbidities including Sprengel deformity may be more common in KFS patients with multilevel cervical fusions. These slides can be retrieved under Electronic Supplementary Material.

Responsiveness of depression and its influence on surgical outcomes of lumbar degenerative diseases.

OBJECTIVE: To demonstrate the responsiveness of depression after surgery for lumbar degenerative disease and to verify the impact of this condition on surgical outcomes. PATIENT SAMPLE: A prospective cohort study with 91 patients with lumbar degenerative diseases who were evaluated preoperatively, at 30 days and 1 year postoperatively. OUTCOME MEASURES: Evolution of depression between the follow-ups and its correlation with satisfaction. METHODS: Depression was assessed with Beck Depression Inventory. According to depression responsiveness, patients were classified into four groups: NN = no depression; ND = normal during the preoperative period and depression within 1 year; DN = depression during the preoperative period and normal within 1 year; DD = depression during the preoperative period and within 1 year. RESULTS: Prevalence of preoperative depression was 28.6% and 17.6% within 1 year postoperatively. Most patients (65.4%) with depression in the preoperative period recovered postoperatively. Poor preoperative HRQoL measures were associated with higher rates of responsiveness of depression during the follow-up. Patients with depression at the 1-year postoperative follow-up had a worse functional outcome. Patients who improved from depression had similar outcome to those without depression. Dissatisfaction within 1 year postoperatively was greater in patients who become depressed after surgery and remain depressed at 1-year follow-up (NN = 8.8%; ND = 42.9%; DN = 17.6%; DD = 44.4%; P = 0.012). CONCLUSION: Most patients with depression in the preoperative recover within 1 year postoperatively. Responsiveness of depression is associated with surgical outcomes. The presence of depression after the surgical treatment, independent of when it starts, had a major negative impact on prognosis.

Electrophysiologic deterioration in surgery for thoracic disc herniation: impact of mean arterial pressures on surgical outcome.

OBJECTIVE: Severe thoracic disc herniation leads to increased pressure in adjacent neural structures, which in turn can require an increase in mean arterial pressure (MAP) to maintain adequate spinal cord perfusion. We report a case series of three patients with severe thoracic disc herniation that experienced deteriorations in motor-evoked potentials (MEPs) and somatosensory evoked potentials (SSEPs) following induction of general anesthesia, but prior to decompression of the neural elements. METHODS: In-depth chart reviews were completed for each patient from their initial presentation to long-term post-operative course. Careful attention was taken with regards to MAP at induction of each operative case. RESULTS: The origin of the decreased signals in all patients was thought to relate to inadequate cord perfusion pressures. Two of the patients recovered pre-operative neurologic function while the third was left with mild post-operative paraparesis. Mean arterial pressures at time of deterioration were noted to be 58, 80, and 60 mmHg. These measurements represented MAPs approximately 65, 92, and 60 % those of baseline values, respectively. CONCLUSION: Based on these experiences, the authors' institution has adopted new guidelines in the setting of thoracic disc herniations that includes pre-operative optimization of volume status, placement of an awake arterial line prior to induction of anesthesia, use of MEP and SSEP electrophysiologic monitoring, careful selection of anesthetic, and aggressive maintenance of MAPs >110 % of preoperative values at all times prior to decompression of the spinal cord.

A comparative effectiveness trial of postoperative management for lumbar spine surgery: changing behavior through physical therapy (CBPT) study protocol.

BACKGROUND: The United States has the highest rate of lumbar spine surgery in the world, with rates increasing over 200% since 1990. Medicare spends over $1 billion annually on lumbar spine surgery. Despite surgical advances, up to 40% of patients report chronic pain and disability following surgery. Our work has demonstrated that fear of movement is a risk factor for increased pain and disability and decreased physical function in patients following lumbar spine surgery for degenerative conditions. Cognitive-behavioral therapy and self-management treatments have the potential to address psychosocial risk factors and improve outcomes after spine surgery, but are unavailable or insufficiently adapted for postoperative care. Our research team developed a cognitive-behavioral based self-management approach to postoperative rehabilitation (Changing Behavior through Physical Therapy (CBPT)). Pilot testing of the CBPT program demonstrated greater improvement in pain, disability, physical and mental health, and physical performance compared to education. The current study compares which of two treatments provided by telephone - a CBPT Program or an Education Program about postoperative recovery - are more effective for improving patient-centered outcomes in adults following lumbar spine surgery for degenerative conditions. METHODS/DESIGN: A multi-center, comparative effectiveness trial will be conducted. Two hundred and sixty patients undergoing lumbar spine surgery for degenerative conditions will be recruited from two medical centers and community surgical practices. Participants will be randomly assigned to CBPT or Education at 6 weeks following surgery. Treatments consist of six weekly telephone sessions with a trained physical therapist. The primary outcome will be disability and secondary outcomes include pain, general health, and physical activity. Outcomes will be assessed preoperatively and at 6 weeks, 6 months and 12 months after surgery by an assessor masked to group allocation. DISCUSSION: Effective rehabilitation treatments that can guide clinicians in their recommendations, and patients in their actions will have the potential to effect change in current clinical practice. TRIAL REGISTRATION: NCT02184143.

Cost-effectiveness of lumbar discectomy and single-level fusion for spondylolisthesis: experience with the NeuroPoint-SD registry.

OBJECT: There is significant practice variation and uncertainty as to the value of surgical treatments for lumbar spine disorders. The authors' aim was to establish a multicenter registry to assess the efficacy and costs of common lumbar spinal procedures by using prospectively collected outcomes. METHODS: An observational prospective cohort study was completed at 13 academic and community sites. Patients undergoing single-level fusion for spondylolisthesis or single-level lumbar discectomy were included. The 36-Item Short Form Health Survey (SF-36) and Oswestry Disability Index (ODI) data were obtained preoperatively and at 1, 3, 6, and 12 months postoperatively. Power analysis estimated a sample size of 160 patients: lumbar disc (125 patients) and lumbar listhesis (35 patients). The quality-adjusted life year (QALY) data were calculated using 6-dimension utility index scores. Direct costs and complication costs were estimated using Medicare reimbursement values from 2011, and indirect costs were estimated using the human capital approach with the 2011 US national wage index. Total costs equaled $14,980 for lumbar discectomy and $43,852 for surgery for lumbar spondylolisthesis. RESULTS: There were 198 patients enrolled over 1 year. The mean age was 46 years (49% female) for lumbar discectomy (n = 148) and 58.1 years (60% female) for lumbar spondylolisthesis (n = 50). Ten patients with disc herniation (6.8%) and 1 with listhesis (2%) required repeat operation at 1 year. The overall 1-year follow-up rate was 88%. At 30 days, both lumbar discectomy and single-level fusion procedures were associated with significant improvements in ODI, visual analog scale, and SF-36 scores (p = 0.0002), which persisted at the 1-year evaluation (p < 0.0001). By 1 year, more than 80% of patients in each cohort who were working preoperatively had returned to work. Lumbar discectomy was associated with a gain of 0.225 QALYs over the 1-year study period ($66,578/QALY gained). Lumbar spinal fusion for Grade I listhesis was associated with a gain of 0.195 QALYs over the 1-year study period ($224,420/QALY gained). CONCLUSIONS: This national spine registry demonstrated successful collection of high-quality outcomes data for spinal procedures in actual practice. These data are useful for demonstrating return to work and cost-effectiveness following surgical treatment of single-level lumbar disc herniation or spondylolisthesis. One-year cost per QALY was obtained, and this cost per QALY is expected to improve further by 2 years. This work sets the stage for real-world analysis of the value of health interventions.

Ehlers-Danlos Syndrome is Associated with Increased Rates of Adjacent Segment Disease Following TLIF: A Propensity Matched Study.

BACKGROUND: Ehlers-Danlos syndrome (EDS) is a collection of connective tissue disorders which are often associated with tissue laxity and disc degeneration. However, the implications of EDS on the risk of adjacent segment disease (ASD) after transforaminal lumbar interbody fusion (TLIF) are not well described. The objective of this study is to compare the rates of ASD among patients with EDS and those without EDS. METHODS: Patients who underwent 1-3 level TLIF for degenerative disc disease between 2010-2022 were identified using the PearlDiver Mariner all-claims insurance database. Patients with all types of EDS were included. Patients undergoing surgery for tumors, trauma, or infection were excluded. 1:1 propensity matching was performed using demographic factors, medical comorbidities, and surgical factors which were significantly associated with ASD in a linear regression model. The primary outcome measure was the development of ASD. The secondary outcomes were the development of pseudoarthrosis, medical complications, and surgical complications. RESULTS: Propensity matching resulted in 2 equal groups of 85 patients who did or did not have EDS and underwent 1-3 level TLIF. Patients without EDS were less likely to experience ASD (RR 0.18, 95% CI 0.09-0.35, P < 0.001). There was no significant difference between the 2 patient groups with regards to a diagnosis of pseudoarthrosis, and there was no significant difference for all-cause medical and surgical complications between the 2 patient groups. CONCLUSIONS: After propensity matching to control for confounding variables, the findings of this study suggest that EDS may be associated with an increased risk of ASD following TLIF. Future studies are needed to corroborate these findings.

Cannabis Use is Associated With Higher Rates of Pseudarthrosis Following TLIF: A Multi-Institutional Matched-Cohort Study.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: To compare the rates of pseudarthrosis in patients undergoing 1 to 3 level transforaminal lumbar interbody fusion (TLIF) procedures between cannabis users and noncannabis users. SUMMARY OF BACKGROUND DATA: Recreational use of cannabis is common, though it remains poorly studied and legally ambiguous in the United States. Patients with back pain may turn to adjunctive use of cannabis to manage their pain. However, the implications of cannabis use on the achievement of bony fusion are not well-characterized. METHODS: Patients who underwent 1 to 3 level TLIF for degenerative disc disease or degenerative spondylolisthesis between 2010 and 2022 were identified using the PearlDiver Mariner all-claims insurance database. Cannabis users were identified with ICD 10 code F12.90. Patients undergoing surgery for nondegenerative pathologies such as tumors, trauma, or infection were excluded. 1:1 exact matching was performed using demographic factors, medical comorbidities, and surgical factors which were significantly associated with pseudarthrosis in a linear regression model. The primary outcome measure was development of pseudarthrosis within 24 months after 1 to 3 level TLIF. The secondary outcomes were the development of all-cause surgical complications as well as all-cause medical complications. RESULTS: A 1:1 exact matching resulted in two equal groups of 1593 patients who did or did not use cannabis and underwent 1 to 3 level TLIF. Patients who used cannabis were 80% more likely to experience pseudarthrosis compared with patients who do not [relative risk (RR): 1.816, 95% CI: 1.291-2.556, P <0.001]. Similarly, cannabis use was associated with significantly higher rates of all-cause surgical complications (RR: 2.350, 95% CI: 1.399-3.947, P =0.001) and all-cause medical complications (RR: 1.934, 95% CI: 1.516-2.467, P <0.001). CONCLUSION: After 1:1 exact matching to control for confounding variables, the findings of this study suggest that cannabis use is associated with higher rates of pseudarthrosis, as well as higher rates of all-cause surgical and all-cause medical complications. Further studies are needed to corroborate our findings.

Outcome science in practice: an overview and initial experience at the Vanderbilt Spine Center.

In terms of policy, research, quality improvement, and practice-based learning, there are essential principles--namely, quality, effectiveness, and value of care--needed to navigate changes in the current and future US health care environment. Patient-centered outcome measurement lies at the core of all 3 principles. Multiple measures of disease-specific disability, generic health-related quality of life, and preference-based health state have been introduced to quantify disease impact and define effectiveness of care. This paper reviews the basic principles of patient outcome measurement and commonly used outcome instruments. The authors provide examples of how utilization of outcome measurement tools in everyday neurosurgical practice can facilitate practice-based learning, quality improvement, and real-world comparative effectiveness research, as well as promote the value of neurosurgical care.

Robotic and navigated pedicle screws are safer and more accurate than fluoroscopic freehand screws: a systematic review and meta-analysis.

BACKGROUND CONTEXT: Navigated and robotic pedicle screw placement systems have been developed to improve the accuracy of screw placement. However, the literature comparing the safety and accuracy of robotic and navigated screw placement with fluoroscopic freehand screw placement in thoracolumbar spine surgery has been limited. PURPOSE: To perform a systematic review and meta-analysis of randomized control trials that compared the accuracy and safety profiles of robotic and navigated pedicle screws with fluoroscopic freehand pedicle screws. STUDY DESIGN/SETTING: Systematic review and meta-analysis PATIENT SAMPLE: Only randomized controlled trials comparing robotic-assisted or navigated pedicle screws placement with freehand pedicle screw placement in the thoracolumbar spine were included. OUTCOME MEASURES: Odds ratio (OR) estimates for screw accuracy according to the Gertzbein-Robbins scale and relative risk (RR) for various surgical complications. METHODS: We systematically searched PubMed and EMBASE for English-language studies from inception through April 7, 2022, including references of eligible articles. The search was conducted according to PRISMA guidelines. Two reviewers conducted a full abstraction of all data, and one reviewer verified accuracy. Information was extracted on study design, quality, bias, participants, and risk estimates. Data and estimates were pooled using the Mantel-Haenszel method for random-effects meta-analysis. RESULTS: A total of 14 papers encompassing 12 randomized controlled trials were identified (n=892 patients, 4,046 screws). The pooled analysis demonstrated that robotic and navigated pedicle screw placement techniques were associated with higher odds of screw accuracy (OR 2.66, 95% CI 1.24-5.72, p=.01). Robotic and navigated screw placement was associated with a lower risk of facet joint violations (RR 0.09, 95% CI 0.02-0.38, p<.01) and major complications (RR 0.31, 95% CI 0.11-0.84, p=.02). There were no observed differences between groups in nerve root injury (RR 0.50, 95% CI 0.11-2.30, p=.37), or return to operating room for screw revision (RR 0.28, 95% CI 0.07-1.13, p=.07). CONCLUSIONS: These estimates suggest that robotic and navigated screw placement techniques are associated with higher odds of screw accuracy and superior safety profile compared with fluoroscopic freehand techniques. Additional randomized controlled trials will be needed to further validate these findings.

Catastrophic acute failure of pelvic fixation in adult spinal deformity requiring revision surgery: a multicenter review of incidence, failure mechanisms, and risk factors.

OBJECTIVE: There are few prior reports of acute pelvic instrumentation failure in spinal deformity surgery. The objective of this study was to determine if a previously identified mechanism and rate of pelvic fixation failure were present across multiple institutions, and to determine risk factors for these types of failures. METHODS: Thirteen academic medical centers performed a retrospective review of 18 months of consecutive adult spinal fusions extending 3 or more levels, which included new pelvic screws at the time of surgery. Acute pelvic fixation failure was defined as occurring within 6 months of the index surgery and requiring surgical revision. RESULTS: Failure occurred in 37 (5%) of 779 cases and consisted of either slippage of the rods or displacement of the set screws from the screw tulip head (17 cases), screw shaft fracture (9 cases), screw loosening (9 cases), and/or resultant kyphotic fracture of the sacrum (6 cases). Revision strategies involved new pelvic fixation and/or multiple rod constructs. Six patients (16%) who underwent revision with fewer than 4 rods to the pelvis sustained a second acute failure, but no secondary failures occurred when at least 4 rods were used. In the univariate analysis, the magnitude of surgical correction was higher in the failure cohort (higher preoperative T1-pelvic angle [T1PA], presence of a 3-column osteotomy; p < 0.05). Uncorrected postoperative deformity increased failure risk (pelvic incidence-lumbar lordosis mismatch > 10°, higher postoperative T1PA; p < 0.05). Use of pelvic screws less than 8.5 mm in diameter also increased the likelihood of failure (p < 0.05). In the multivariate analysis, a larger preoperative global deformity as measured by T1PA was associated with failure, male patients were more likely to experience failure than female patients, and there was a strong association with implant manufacturer (p < 0.05). Anterior column support with an L5-S1 interbody fusion was protective against failure (p < 0.05). CONCLUSIONS: Acute catastrophic failures involved large-magnitude surgical corrections and likely resulted from high mechanical strain on the pelvic instrumentation. Patients with large corrections may benefit from anterior structural support placed at the most caudal motion segment and multiple rods connecting to more than 2 pelvic fixation points. If failure occurs, salvage with a minimum of 4 rods and 4 pelvic fixation points can be successful.

Association between biomechanical parameters and concussion in helmeted collisions in American football: a review of the literature.

OBJECT: The authors' goal was to better define the relationship between biomechanical parameters of a helmeted collision and the likelihood of concussion. METHODS: The English-language literature was reviewed in search of scholarly articles describing the rotational and translational accelerations observed during all monitored impact conditions that resulted in concussion at all levels of American football. RESULTS: High school players who suffer concussion experience an average of 93.9g of translational acceleration (TA) and 6505.2 rad/s(2) of rotational acceleration (RA). College athletes experience an average of 118.4g of TA and 5311.6 rad/s(2) of RA. While approximately 3% of collisions are associated with TAs greater than the mean TA associated with concussion, only about 0.02% of collisions actually result in a concussion. Associated variables that determine whether a player who experiences a severe collision also experiences a concussion remain hypothetical at present. CONCLUSIONS: The ability to reliably predict the incidence of concussion based purely on biomechanical data remains elusive. This study provides novel, important information that helps to quantify the relative insignificance of biomechanical parameters in prediction of concussion risk. Further research will be necessary to better define other factors that predispose to concussion.

Noninvasive electrical stimulation as an adjunct to fusion procedures: a systematic review and meta-analysis.

OBJECTIVE: Noninvasive electrical stimulation represents a distinct group of devices used to augment fusion rates. However, data regarding outcomes of noninvasive electrical stimulation have come from a small number of studies. The goal of this systematic review and meta-analysis was to determine outcomes of noninvasive electrical stimulation used as an adjunct to fusion procedures to improve rates of successful fusion. METHODS: PubMed, Embase, and the Cochrane Clinical Trials database were searched according to search strategy and PRISMA guidelines. Random-effects meta-analyses of fusion rates with the three main modalities of noninvasive electrical stimulation, capacitively coupled stimulation (CCS), pulsed electromagnetic fields (PEMFs), and combined magnetic fields (CMFs), were conducted using R version 4.1.0 (The R Foundation for Statistical Computing). Both retrospective studies and clinical trials were included. Animal studies were excluded. Risk-of-bias analysis was performed with the Risk of Bias 2 (RoB 2) and Risk of Bias in Nonrandomized Studies of Interventions (ROBINS-I) tools. RESULTS: Searches of PubMed, Embase, and the Cochrane Clinical Trials database identified 8 articles with 1216 participants meeting criteria from 213 initial results. There was a high overall risk of bias identified for the majority of randomized studies. No meta-analysis could be performed for CCS as only 1 study was identified. Meta-analysis of 6 studies of fusion rates in PEMF did not find any difference between treatment and control groups (OR 1.89, 95% CI 0.36-9.80, p = 0.449). Meta-analysis of 2 studies of CMF found no difference in fusion rates between control and treatment groups (OR 0.90, 95% CI 0.07-11.93, p = 0.939). Subgroup analysis of PEMF was limited given the small number of studies and patients, although significantly increased fusion rates were seen in some subgroups. CONCLUSIONS: This meta-analysis of clinical outcomes and fusion rates in noninvasive electrical stimulation compared to no stimulation did not identify any increases in fusion rates for any modality. A high degree of heterogeneity between studies was noted. Although subgroup analysis identified significant differences in fusion rates in certain groups, these findings were based on a small number of studies and further research is needed. This analysis does not support routine use of these devices to augment fusion rates, although the data are limited by a high risk of bias and a small number of available studies.

C1 Lateral Mass Screw Placement Through Endonasal Corridor for Purpose of O-C1 Fusion: Morphometric Analysis in Cadaveric Specimens.

BACKGROUND: Odontoidectomy may pose some risks for O-C1 and/or C1-C2 instability, with previous authors reporting techniques for endonasal C1-C2 fusion. However, no technique for endonasal O-C1 fusion currently exists. We sought to describe the feasibility of endonasal anterior C1 (AC1) screw placement for endonasal O-C1 fusion. METHODS: Seven adult cadaveric heads were studied for endonasal placement of 14 C1 screws. Using thin-cut computed tomography (CT)-based "snapshot" neuronavigation assistance, 4 mm x 22 mm screws were placed in the C1 lateral mass using a 0° driver. Post-placement CT scans were obtained to determine site-of-entry measured from C1 anterior tubercle, screw angulation in axial and sagittal planes, and screw proximity to the central canal and foramen transversarium. RESULTS: Average site-of-entry was 16.57 mm lateral, 2.23 mm rostral, and 5.53 mm deep to the anterior-most portion of the C1 ring. Average axial angulation was 19.49° lateral to midline, measured at the C1 level. Average sagittal angulation was 13.22° inferior to the palatal line, measured from the hard palate to the opisthion. Bicortical purchase was achieved in 11 screws (78.6%). Partial breach of the foramen transversarium was observed in 2 screws (14.3%), violation of the O-C1 joint space in 1 (7.1%), and violation of the central canal in 0 (0%). Average minimum screw distances from the unviolated foramen transversaria and central canal were 1.97 mm and 4.04 mm. CONCLUSIONS: Navigation-assisted endonasal placement of AC1 screws is feasible. Additional studies should investigate the biomechanical stability of anterior C1 screw-plating systems, with anterior condylar screws as superior fixation point, compared to traditional posterior O-C1 fusion.