Pennington, Zach

OBJECTIVE Vertebral artery injury (VAI), a complication of blunt trauma, may cause posterior circulation stroke. An association of disease severity, classified in Denver grades, with stroke risk has not been shown. Using a literature-based analysis, the authors estimated the incidence of VAI following blunt trauma with the aim to investigate the impact of Denver grade and bilateral VAI on stroke occurrence. METHODS A systematic review of the literature on VAI following blunt trauma was conducted, and data on its incidence, the severity per Denver grade, and stroke occurrence were collected. The incidence of VAI and stroke occurrence were analyzed cumulatively and between Denver grades. A meta-analysis with random-effects models was performed. RESULTS Fifty-six studies including 2563 patients were identified. The overall incidence of VAI was 0.49% among blunt trauma cases and 14.5% among patients screened via any type of angiography. The incidence rates of bilateral VAI and concurrent carotid injury among all VAIs were 12.3% and 19.2%, respectively. VAI severity by Denver grade was as follows: grade I, 23.4%; grade II, 28.2%; grade III, 5.8%; grade IV, 42.1%; and grade V, 0.5%. The overall stroke risk was 5.32%, differing significantly among lesions of different Denver grades (p = 0.02). Grade III and IV lesions had the highest stroke prevalence (9.8% and 10.9% respectively), while strokes occurred significantly less frequently in patients with grade I and II lesions (1.9% and 3.0%, respectively). Denver grade V cases were too rare for meaningful analysis. Bilateral VAI was associated with a 33.2% stroke prevalence. The association between Denver grade and stroke occurrence persisted in a sensitivity subanalysis including only unilateral cases (p = 0.03). CONCLUSIONS VAI complicates a small yet nontrivial fraction of blunt trauma cases, with Denver grade IV lesions being the most common. This is the first study to document a significantly higher stroke prevalence among grade III and IV VAIs compared with grade I and II VAIs independently from bilaterality. Bilateral VAIs carry a significantly higher stroke rate.

OBJECTIVE Lateral lumbar interbody fusion including anterior-to-psoas oblique lumbar interbody fusion has conventionally relied on pedicle screw placement (PSP) for construct stabilization. Single-position surgery with lumbar interbody fusion in the lateral decubitus position with concomitant PSP has been associated with increased operative efficiency. What remains unclear is the accuracy of PSP with robotic guidance when compared with the more familiar prone patient positioning. The present study aimed to compare robot-assisted screw placement accuracy between patients with instrumentation placed in the prone and lateral positions. METHODS The authors identified all consecutive patients treated with interbody fusion and PSP in the prone or lateral position by a single surgeon between January 2019 and October 2022. All pedicle screws placed were analyzed using CT scans to determine appropriate positioning according to the Gertzbein-Robbins classification grading system (grade C or worse was considered as a radiographically significant breach). Multivariate logistic regression models were constructed to identify risk factors for the occurrence of a radiographically significant breach. RESULTS Eighty-nine consecutive patients (690 screws) were included, of whom 46 (477 screws) were treated in the prone position and 43 (213 screws) in the lateral decubitus position. There were fewer breaches in the prone (n = 13, 2.7%) than the lateral decubitus (n = 15, 7.0%) group (p = 0.012). Nine (1.9%) radiographically significant breaches occurred in the prone group compared with 10 (4.7%) in the lateral decubitus group (p = 0.019), for a prone versus lateral decubitus PSP accuracy rate of 98.1% versus 95.3%. There were no significant differences in BMI between prone versus lateral decubitus cohorts (30.1 vs 29.6) or patients with screw breach versus those without (31.2 vs 29.5). In multivariate models, the prone position was the only significant protective factor for screw accuracy; no other significant risk factors for screw breach were identified. CONCLUSIONS The present data suggest that pedicle screws placed with robotic assistance have higher placement accuracy in the prone position. Further studies will be needed to validate the accuracy of PSP in the lateral position as single-position surgery becomes more commonplace in the treatment of spinal disorders.

OBJECTIVE While single-position surgery (SPS) eliminates the need for patient repositioning, the placement of screws in the unconventional lateral position poses unique challenges related to asymmetry relative to the surgical table. Use of robotic guidance or intraoperative navigation can help to overcome this. The aim of this study was to compare the relative accuracies offered by these various navigation modalities for pedicle screws placed in lateral SPS. METHODS According to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the PubMed/Medline, Embase, and Cochrane Library databases were queried for studies reporting pedicle screw placement accuracy using fluoroscopic, CT-navigated, O-arm, or robotic guidance in lateral SPS, and a systematic review and meta-analysis was performed. Included studies all compared evaluated screw placement accuracy in lateral SPS using a single navigation method. Quality assessment was performed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system; risk of bias was assessed using the Newcastle-Ottawa Scale and the Joanna Briggs Institute checklist. The primary outcome, rate of pedicle screw breach, was analyzed using random-effects meta-analysis. RESULTS Eleven studies were included comprising 548 patients who underwent the placement of instrumentation with 2488 screws. For the fluoroscopic, CT-navigated, O-arm, and robotic guidance cohorts, there were 3, 2, 3, and 3 studies, respectively. Breach rates by modality were as follows: fluoroscopic guidance (6.6%), CT navigation (4.7%), O-arm (3.9%), and robotic guidance (3.9%). Random-effects meta-analysis showed a significant difference between studies, with an overall breach rate of 4.9% (95% CI 3.1%–7.5%; p < 0.001); however, testing for subgroup differences failed to show a significant difference between guidance modalities (QM = 0.69, df = 3; p = 0.88). Heterogeneity between studies was significant (I2 = 79.0%, τ2 = 0.41, χ2 = 47.65, df = 10; p < 0.001). CONCLUSIONS Robotic guidance of screws is noninferior to alternative guidance modalities in lateral SPS; however, additional prospective studies directly comparing different guidance types are merited.

BACKGROUND AND OBJECTIVES: Sacrectomy is often the treatment of choice to provide the greatest chance of progression-free and overall survival for patients with primary malignant bone tumors of the sacrum. After midsacrectomy, the stability of the sacropelvic interface is diminished, resulting in insufficiency fractures. Traditional stabilization involves lumbopelvic fixation but subjects normal mobile segments to fusion. The purpose of this study was to determine whether standalone intrapelvic fixation is a safe adjunct to midsacrectomy, avoiding both sacral insufficiency fractures and the morbidity of instrumenting into the mobile spine. METHODS: A retrospective study identified all patients who underwent resection of sacral tumors at 2 comprehensive cancer centers between June 2020 and July 2022. Demographic, tumor-specific, operative characteristics and outcome data were collected. The primary outcome was presence of sacral insufficiency fractures. A retrospective data set of patients undergoing midsacrectomy without hardware placement was collected as a control. RESULTS: Nine patients (5 male, 4 female), median age 59 years, underwent midsacrectomy with concomitant placement of standalone pelvic fixation. No patients developed insufficiency fractures during the 216 days of clinical and 207 days of radiographic follow-up. There were no adverse events attributable to the addition of standalone pelvic fixation. In our historical cohort of partial sacrectomies without stabilization, there were 4/25 patients (16%) with sacral insufficiency fractures. These fractures appeared between 0 and 5 months postoperatively. CONCLUSION: A novel standalone intrapelvic fixation after partial sacrectomy is a safe adjunct to prevent postoperative sacral insufficiency fractures in patients undergoing midsacrectomy for tumor. Such a technique may allow for long-term sacropelvic stability without sacrificing mobile lumbar segments.

Study Design. A cross-sectional study was performed using the National Institutes of Health All of Us survey database. Objective. The aim of this study was to assess socioeconomic and racial disparities in the perception of personal health, health literacy, and healthcare access among spine oncology patients. Summary of Background Data. Racial, ethnic, and socioeconomic disparities in health literacy and perception of health status have been described for many disease processes. However, few studies have assessed the prevalence of these disparities among spine oncology patients. Methods. Adult spine oncology patients, identified using ICD-9/10-CM codes, were categorized by race/ethnicity: White/Caucasian (WC), Black/African-American (BAA), and Non-White Hispanic (NWH). Demographics and socioeconomic status were assessed. Questionnaire responses regarding baseline health status, perception of health status, health literacy, and barriers to healthcare were compared. Results. Of the 1,175 patients identified, 207 (17.6%) were BAA, 267 (22.7%) were NWH, and 701 (59.7%) were WC. Socioeconomic status varied among cohorts, with WC patients reporting higher levels of education (P<0.001), annual income greater than $50K (P<0.001), and home ownership (P<0.001). BAA and NWH patients reported greater rates of 7-day “Severe fatigue” (P<0.001) and “10/10 pain” (P<0.001) and lower rates of “Completely” able to perform everyday activities (P<0.001). WC patients had a higher response rate for “Excellent/Very Good” regarding their own general health (P<0.001) and quality (P<0.001). The WC cohort had a significantly higher proportion of patients responding “Never” when assessing difficulty understanding (P<0.001) and needing assistance with health materials (P<0.001). BAA and NWH were significantly less likely to report feeling “Extremely” confident with medical forms (P<0.001). BAA and NWH had significantly higher response rates to feeling “Somewhat Worried” about healthcare costs (P<0.001) and with delaying medical care given “Can’t Afford Co-pay” (P<0.001). Conclusion. We identified disparities in perception of health status, literacy, and access among spine oncology patients. Level of Evidence. 4

OBJECTIVE The purpose of this study was to analyze risk factors for sacral fracture following noninstrumented partial sacral amputation for en bloc chordoma resection. METHODS A multicenter retrospective chart review identified patients who underwent noninstrumented partial sacral amputation for en bloc chordoma resection with pre- and postoperative imaging. Hounsfield units (HU) were measured in the S1 level. Sacral amputation level nomenclature was based on the highest sacral level with bone removed (e.g., S1 foramen amputation at the S1–2 vestigial disc is an S2 sacral amputation). Variables collected included basic demographics, patient comorbidities, surgical approach, preoperative radiographic details, neoadjuvant and adjuvant radiation therapy, and postoperative sacral fracture data. RESULTS A total of 101 patients (60 men, 41 women) were included; they had an average age of 69 years, BMI of 29 kg/m2, and follow-up of 60 months. The sacral amputation level was S1 (2%), S2 (37%), S3 (44%), S4 (9%), and S5 (9%). Patients had a posterior-only approach (77%) or a combined anterior–posterior approach (23%), with 10 patients (10%) having partial sacroiliac (SI) joint resection. Twenty-seven patients (27%) suffered a postoperative sacral fracture, all occurring between 1 and 7 months after the index surgery. Multivariable logistic regression analysis demonstrated S1 or S2 sacral amputation level (p = 0.001), combined anterior–posterior approach (p = 0.0064), and low superior S1 HU (p = 0.027) to be independent predictors of sacral fracture. The fracture rate for patients with superior S1 HU < 225, 225–300, and > 300 was 38%, 15%, and 9%, respectively. An optimal superior S1 HU cutoff of 300 was found to maximize sensitivity (89%) and specificity (42%) in predicting postamputation sacral fracture. In addition, the fracture rate for patients who underwent partial SI joint resection was 100%. CONCLUSIONS Patients with S1 or S2 partial sacral amputations, a combined anterior–posterior surgical approach, low superior S1 HU, and partial SI joint resection are at higher risk for postoperative sacral fracture following en bloc chordoma resection and should be considered for spinopelvic instrumentation at the index procedure.

OBJECTIVE Idiopathic normal pressure hydrocephalus (iNPH) results in significant morbidity in the elderly with symptoms of dementia, gait instability, and urinary incontinence. In well-selected patients, ventriculoperitoneal shunt (VPS) placement often results in clinical improvement. Most postshunt assessments of patients rely on subjective scales. The goal of this study was to assess the utility of remote activity monitoring to provide objective evidence of gait improvement following VPS placement for iNPH. METHODS Patients with iNPH were prospectively enrolled and fitted with 5 activity monitors (on the hip and bilateral thighs and ankles) that they wore for 4 days preoperatively within 30 days of surgery and for 4 days within 30 days postoperatively. Monitors collected continuous data for number of steps, cadence, body position (upright, prone, supine, and lateral decubitus), gait entropy, and the proportion of each day spent active or static. Data were retrieved from the devices and a comparison of pre- and postoperative movement assessment was performed. The gait data were also correlated with formal clinical gait assessments before and after lumbar puncture and with motion analysis laboratory testing at baseline and 1 month and 1 year after VPS placement. RESULTS Twenty patients fulfilled the inclusion and exclusion criteria (median age 76 years). The baseline median number of daily steps was 1929, the median percentage of the day spent inactive was 70%, the median percentage of the day with a static posture was 95%, the median gait velocity was 0.49 m/sec, and the median number of steps required to turn was 8. There was objective improvement in median entropy from pre- to postoperatively, increasing from 0.6 to 0.8 (p = 0.002). There were no statistically significant differences for any of the remaining variables measured by the activity monitors when comparing the preoperative to the 1-month postoperative time point. All variables from motion analysis testing showed statistically significant differences or a trend toward significance at 1 year after VPS placement. Among the significantly correlated variables at baseline, cadence was inversely correlated with percentage of gait cycle spent in the support phase (contact with ground vs swing phase). CONCLUSIONS This pilot study suggests that activity monitoring provides an early objective measure of improvement in gait entropy after VPS placement among patients with iNPH, although a more significant improvement was noted on the detailed clinical gait assessments. Further long-term studies are needed to determine the utility of remote monitoring for assessing gait improvement following VPS placement.

OBJECTIVE Patients with brachial plexus avulsion (BPA) experience chronic deafferentation pain characterized by two patterns: continuous background pain and electrical shooting paroxysmal attacks. The authors’ aim was to report the effectiveness and safety of dorsal root entry zone (DREZ) lesioning in relieving the two forms of pain over short and long periods. METHODS All patients who underwent DREZ lesioning performed by the senior author for medically refractory BPA-related pain between July 1, 2016, and June 30, 2020, in Johns Hopkins Hospital were followed up. The intensity levels for continuous and paroxysmal pains were evaluated using the numeric rating scale (NRS) preoperatively and at 4 time points postsurgery, including the day of discharge, with a mean hospital stay of 5.6 ± 1.8 days; first postoperative clinic visit (33.0 ± 15.7 days); short-term follow-up (4.0 ± 1.4 months); and long-term follow-up (3.1 ± 1.3 years). The percent of pain relief according to the NRS was categorized into excellent (≥ 75%), fair (25%–74%), and poor (< 25%). RESULTS A total of 19 patients were included, with 4 (21.1%) lost to long-term follow-up. The mean age was 52.7 ± 13.6 years; 16 (84.2%) were men, and 10 (52.6%) had left-sided injuries. A motor vehicle accident was the most common etiology of BPA (n = 16, 84.2%). Preoperatively, all patients had motor deficits, and 8 (42.1%) experienced somatosensory deficits. The greatest pain relief was observed at the first postoperative and short-term follow-up visits, with the lowest proportions of patients having continuous pain (26.3% and 23.5%, respectively) and paroxysmal pain (5.3% and 5.9%, respectively). Also, the highest reductions in mean NRS scores were observed for first postoperative and short-term follow-up visits (continuous 1.1 ± 2.1 and 1.1 ± 2.3; paroxysms 0.4 ± 1.4 and 0.5 ± 1.7, respectively) compared to the preoperative symptomatology (continuous 6.7 ± 3.0; paroxysms 7.9 ± 4.3) (p < 0.001). Most patients had excellent relief of continuous pain (82.4% and 81.3%) and of paroxysms (90.9% and 90.0%) at the first postoperative visit and short-term follow-up visit, respectively. The pain relief benefits had diminished by 3 years after surgery but remained significantly better than in the preoperative assessment. At the last evaluation, the proportion of patients achieving excellent relief of paroxysmal pain (66.7%) was double that for continuous pain (35.7%) (p < 0.001). New sensory phenomena were observed among 10 patients (52.6%), and 1 patient developed a motor deficit. CONCLUSIONS DREZ lesioning is an effective and safe option for relieving BPA-associated pain, with good long-term outcomes and better benefits for paroxysmal pain than for the continuous pain component.

OBJECTIVE Infuse bone graft is a widely used osteoinductive adjuvant; however, the simple collagen sponge scaffold used in the implant has minimal inherent osteoinductive properties and poorly controls the delivery of the adsorbed recombinant human bone morphogenetic protein–2 (rhBMP-2). In this study, the authors sought to create a novel bone graft substitute material that overcomes the limitations of Infuse and compare the ability of this material with that of Infuse to facilitate union following spine surgery in a clinically translatable rat model of spinal fusion. METHODS The authors created a polydopamine (PDA)–infused, porous, homogeneously dispersed solid mixture of extracellular matrix and calcium phosphates (BioMim-PDA) and then compared the efficacy of this material directly with Infuse in the setting of different concentrations of rhBMP-2 using a rat model of spinal fusion. Sixty male Sprague Dawley rats were randomly assigned to each of six equal groups: 1) collagen + 0.2 µg rhBMP-2/side, 2) BioMim-PDA + 0.2 µg rhBMP-2/side, 3) collagen + 2.0 µg rhBMP-2/side, 4) BioMim-PDA + 2.0 μg rhBMP-2/side, 5) collagen + 20 µg rhBMP-2/side, and 6) BioMim-PDA + 20 µg rhBMP-2/side. All animals underwent posterolateral intertransverse process fusion at L4–5 using the assigned bone graft. Animals were euthanized 8 weeks postoperatively, and their lumbar spines were analyzed via microcomputed tomography (µCT) and histology. Spinal fusion was defined as continuous bridging bone bilaterally across the fusion site evaluated via µCT. RESULTS The fusion rate was 100% in all groups except group 1 (70%) and group 4 (90%). Use of BioMim-PDA with 0.2 µg rhBMP-2 led to significantly greater results for bone volume (BV), percentage BV, and trabecular number, as well as significantly smaller trabecular separation, compared with the use of the collagen sponge with 2.0 µg rhBMP-2. The same results were observed when the use of BioMim-PDA with 2.0 µg rhBMP-2 was compared with the use of the collagen sponge with 20 µg rhBMP-2. CONCLUSIONS Implantation of rhBMP-2–adsorbed BioMim-PDA scaffolds resulted in BV and bone quality superior to that afforded by treatment with rhBMP-2 concentrations 10-fold higher implanted on a conventional collagen sponge. Using BioMim-PDA (vs a collagen sponge) for rhBMP-2 delivery could significantly lower the amount of rhBMP-2 required for successful bone grafting clinically, improving device safety and decreasing costs.

BACKGROUND Minimally invasive surgical techniques are changing the landscape in adult spinal deformity (ASD) surgery, enabling surgical correction to be achievable in increasingly medically complex patients. Spinal robotics are one technology that have helped facilitate this. Here the authors present an illustrative case of the utility of robotics planning workflow for minimally invasive correction of ASD. OBSERVATIONS A 60-year-old female presented with persistent and debilitating low back and leg pain limiting her function and quality of life. Standing scoliosis radiographs demonstrated adult degenerative scoliosis (ADS), with a lumbar scoliosis of 53°, a pelvic incidence–lumbar lordosis mismatch of 44°, and pelvic tilt of 39°. Robotics planning software was utilized for preoperative planning of the multiple rod and 4-point pelvic fixation in the posterior construct. LESSONS To the authors’ knowledge, this is the first report detailing the use of spinal robotics for complex 11-level minimally invasive correction of ADS. Although additional experiences adapting spinal robotics to complex spinal deformities are necessary, the present case represents a proof-of-concept demonstrating the feasibility of applying this technology to minimally invasive correction of ASD.