Vascularization is critical for skull development, maintenance, and healing. Yet, there remains a significant knowledge gap in the relationship of blood vessels to cranial skeletal progenitors during ...these processes. Here, we introduce a quantitative 3D imaging platform to enable the visualization and analysis of high-resolution data sets (>100 GB) throughout the entire murine calvarium. Using this technique, we provide single-cell resolution 3D maps of vessel phenotypes and skeletal progenitors in the frontoparietal cranial bones. Through these high-resolution data sets, we demonstrate that CD31
Emcn
vessels are spatially correlated with both Osterix+ and Gli1+ skeletal progenitors during postnatal growth, healing, and stimulated remodeling, and are concentrated at transcortical canals and osteogenic fronts. Interestingly, we find that this relationship is weakened in mice with a conditional knockout of PDGF-BB in TRAP+ osteoclasts, suggesting a potential role for osteoclasts in maintaining the native cranial microvascular environment. Our findings provide a foundational framework for understanding how blood vessels and skeletal progenitors spatially interact in cranial bone, and will enable more targeted studies into the mechanisms of skull disease pathologies and treatments. Additionally, our technique can be readily adapted to study numerous cell types and investigate other elusive phenomena in cranial bone biology.
STUDY DESIGN.Retrospective cohort study.
OBJECTIVE.To compare short- and long-term outcomes in obese versus nonobese patients undergoing instrumented posterolateral fusion of the lumbar spine.
...SUMMARY OF BACKGROUND DATA.Obesity is an important public health issue due to the negative effects on quality of life. Some studies have shown an association between obesity and higher rates of complications and unfavorable outcomes after spine surgery.
METHODS.We retrospectively reviewed medical records for all adult patients undergoing 1- to 3-level posterolateral fusion for degenerative spine disease between 1992 and 2012 at a single institution. Patients were divided into obese (body mass index > 30 kg/m) and nonobese cohorts to compare complications, reoperation rates, and symptom resolution at the last follow-up. A regression model was used to estimate relative risk ratios.
RESULTS.During the study period, 732 patients underwent lumbar fusion, with 662 (90.44%) nonobese patients and 70 (9.56%) obese patients in the cohort. Obese patients had significantly higher blood loss intraoperatively (P = 0.002) and a longer average length of stay (P = 0.022). Moreover, obesity was independently associated with a significantly increased risk of developing a postoperative complication (risk ratio 2.14; 95% confidence interval, 1.10–4.16) and surgical site infection (risk ratio 3.11; 95% confidence interval, 1.48–6.52). At the last follow-up, a higher proportion of obese patients had radiculopathy (P = 0.018), motor deficits (P = 0.006), sensory deficits (P = 0.008), and bowel or bladder dysfunction (P = 0.006) than nonobese patients.
CONCLUSION.In this study, obese patients undergoing lumbar fusion had higher blood loss, longer lengths of stay, higher complication rates, and worse functional outcomes at the last follow-up than nonobese patients. These findings suggest that both surgeons and patients should acknowledge the significantly increased morbidity profile of obese patients after lumbar fusion.Level of Evidence4
Pedicle screws (PSs) are routinely used for stabilization to enhance fusion in a variety of spinal diseases. Although the accuracy of different PS placement methods has been previously reported, most ...of these studies have been limited to 1 or 2 techniques. The purpose was to determine the current accuracy of PS placement among 4 modalities of PS insertion (freehand FH, fluoroscopy-assisted FA, computed tomography navigation–guided CTNav, and robot-assisted RA) and analyze variables associated with screw misplacement.
A systematic review was performed of peer-reviewed articles reporting PS accuracy of 1 technique from January 1990 to June 2018. Accuracy of PS placement, PS insertion technique, and pedicle breach (PB) data were collected. A meta-analysis was performed to estimate the overall pooled (OP) rates of PS accuracy as a primary outcome, stratified by screw insertion techniques. Potential determinants were analyzed via meta-regression analyses.
Seventy-eight studies with 7858 patients, 51,161 PSs, and 3614 cortical PBs were included. CTNav showed the highest PS placement accuracy compared with other techniques: OP accuracy rates were 95.5%, 93.1%, 91.5%, and 90.5%, via CTNav, FH, FA, and RA techniques, respectively. RA and CTNav were associated with the highest PS accuracy in the thoracic spine, compared with FH.
The OP data show that CTNav has the highest PS accuracy rates. Thoracic PSs were associated with lower accuracy rates; however, RA showed fewer breaches in the thoracic spine compared with FH and FA. Given the heterogeneity among studies, further standardized and comparative investigations are required to confirm our findings.
In this study, the authors sought to determine which US medical schools have produced the most neurosurgery residents and to evaluate potential associations between recruitment and medical school ...characteristics.
Demographic and bibliometric characteristics were collected for 1572 residents in US-based and Accreditation Council for Graduate Medical Education (ACGME)-accredited neurosurgery programs over the 2014 to 2020 match period using publicly available websites. US medical school characteristics were collected, including class size, presence of a home neurosurgery program, number of clinical neurosurgery faculty, research funding, presence of a neurosurgery interest group, and a top 10 ranking via U.S. News & World Report or Doximity. Correlations and associations were then evaluated using Pearson's correlation coefficient (PCC), independent-samples t-test, and univariable or stepwise multivariable linear regression, as appropriate.
Vanderbilt University produced the most neurosurgery residents as a percentage of medical graduates at 3.799%. Case Western Reserve University produced the greatest absolute number of neurosurgery residents (n = 40). The following factors were shown to be associated with a higher mean percentage of graduates entering neurosurgery: number of clinical neurosurgery faculty (PCC 0.509, p < 0.001), presence of a neurosurgery interest group (1.022% ± 0.737% vs 0.351% ± 0.327%, p < 0.001) or home neurosurgery program (1.169% ± 0.766% vs 0.428% ± 0.327%, p < 0.001), allopathic compared with osteopathic school (0.976% ± 0.719% vs 0.232% ± 0.272%, p < 0.001), U.S. News top 10 ranking for neurology and neurosurgery (1.923% ± 0.924% vs 0.757% ± 0.607%, p < 0.001), Doximity top 10 residency program ranking (1.715% ± 0.803% vs 0.814% ± 0.688%, p < 0.001), and amount of NIH funding (PCC 0.528, p < 0.001).
The results of this study have delineated which medical schools produced the most neurosurgery residents currently in training, and the most important independent factors predicting the percentage of graduates entering neurosurgery and the preresidency h-index.
Abstract
BACKGROUND:
Pedicle screws are used to stabilize all 3 columns of the spine, but can be technically demanding to place. Although intraoperative fluoroscopy and stereotactic-guided techniques ...slightly increase placement accuracy, they are also associated with increased radiation exposure to patient and surgeon as well as increased operative time.
OBJECTIVE:
To describe and critically evaluate our 7-year institutional experience with placement of pedicle screws in the thoracic and lumbar spine using a free-hand technique.
METHODS:
We retrospectively reviewed records of all patients undergoing free-hand pedicle screw placement without fluoroscopy in the thoracic or lumbar spine between June 2002 and June 2009. Incidence and extent of cortical breach by misplaced pedicle screw was determined by review of postoperative computed tomography scans. We defined breach as more than 25% of the screw diameter residing outside of the pedicle or vertebral body cortex.
RESULTS:
A total of 964 patients received 6816 free-hand placed pedicle screws in the thoracic or lumbar spine. Indications for hardware placement were degenerative/deformity disease (51.2%), spondylolisthesis (23.7%), tumor (22.7%), trauma (11.3%), infection (7.6%), and congenital (0.9%). A total of 115 screws (1.7%) were identified as breaching the pedicle in 87 patients (9.0%). Breach occurred more frequently in the thoracic than the lumbar spine (2.5% and 0.9%, respectively; P < .0001) and was more often lateral (61.3%) than medial (32.8%) or superior (2.5%). T4 (4.1%) and T6 (4.0%) experienced the highest breach rate, whereas L5 and S1 had the lowest breach rate. Eight patients (0.8%) underwent revision surgery to correct malpositioned screws.
CONCLUSION:
Free-hand pedicle screw placement based on external anatomy alone can be performed with acceptable safety and accuracy and allows avoidance of radiation exposure encountered in fluoroscopic techniques. Image-guided assistance may be most valuable when placing screws between T4 and T6, where breach rates are highest.
This study aimed to identify the factors predicting an increased risk for reoperation in patients who had undergone a lumbar laminectomy.
The authors retrospectively reviewed the electronic medical ...records of all patients who had undergone firsttime, bilateral laminectomy at 1, 2, or 3 levels for lumbar spondylosis at the authors' institution. Patients who underwent fusion, laminotomy, discectomy, or complete facetectomy were excluded. The patients' preoperative symptoms and comorbidities were also obtained from their medical records.
Over an average follow-up period of 46.8 months, of 500 patients who had undergone laminectomy at 1, 2, or 3 levels, 81 patients (16.2%) developed subsequent spinal disorders that required a reoperation. A multiple logistic regression analysis identified smoking as an independent predictor of reoperation (OR 2.15, p = 0.01). Smoking was also an independent predictor of reoperation after a single-level laminectomy (OR 11.3, p = 0.02) and after a multilevel (that is, involving 2 or 3 levels) laminectomy (OR 1.98, p = 0.05). For 72 patients undergoing reoperation only for spinal degeneration, smoking remained an independent, statistically significant predictor of reoperation (OR 2.06, p = 0.04). Nine patients underwent reoperation for nondegenerative conditions (hematoma, wound infection, or wound dehiscence), and in these patients, chronic obstructive pulmonary disease was the only statistically significant predictor of reoperation (OR 8.92, p = 0.03).
Smoking was the strongest predictor of reoperation in patients who had undergone single-level laminectomy, multilevel laminectomy, or reoperation for progression of spinal degeneration. These findings suggest that smokers have worse outcomes of lumbar decompression than nonsmokers.
The authors aimed to characterize which US medical schools have the most female neurosurgery residents and to identify potential associations between medical school characteristics and successful ...recruitment of women pursuing a neurosurgery career.
The authors evaluated a total of 1572 residents in US neurosurgery programs accredited by the Accreditation Council for Graduate Medical Education as of February 2021, representing match cohorts from 2014 to 2020. The authors extracted US medical school characteristics and ranked schools based on the percentages of women graduates entering neurosurgery. They additionally studied yearly trends of the percentage of women constituting incoming neurosurgery resident cohorts as well as associations between female recruitment percentage and medical school characteristics using univariable and stepwise multivariable linear regression (including significant univariable factors).
The cohort consisted of 1255 male and 317 (20%) female residents. Yearly trends indicated a significant drop in incoming female residents in 2016, followed by significant increases in 2017 and 2019. On multivariable analysis, the following factors were associated with a higher average percentage of female graduates entering neurosurgery: total affiliated neurosurgery clinical faculty (β = 0.006, 95% CI 0.001-0.011, p = 0.01), allopathic versus osteopathic schools (β = 0.231, 95% CI 0.053-0.409, p = 0.01), and top 10 U.S. News & World Report ranking (β = 0.380, 95% CI 0.129-0.589, p < 0.01). When the number of female clinical faculty was added to the model, the variable was not statistically significant. Multivariable bibliometric analyses indicated a higher mean preresidency H-index for men, with an even greater gender difference identified in the 2021 H-index.
This study characterizes which medical schools are most successful at recruiting female students who constituted the total neurosurgery resident workforce of the 2020-2021 academic year. The overall number of clinical neurosurgery faculty rather than faculty gender was independently associated with female recruitment. Gender differences in research productivity persisted with control for confounders and increased between preresidency and 2021 time points. Such understanding of factors that influence the recruitment of women can help improve female representation in neurosurgery residency training moving forward.
Abstract Background context A persistent challenge in spine surgery is improving screw fixation in patients with poor bone quality. Augmenting pedicle screw fixation with cement appears to be a ...promising approach. Purpose The purpose of this study was to survey the literature and assess the previous biomechanical studies on pedicle screw augmentation with cement to provide in-depth discussions of the biomechanical benefits of multiple parameters in screw augmentation. Study design/Setting This is a systematic literature review. Methods A search of Medline was performed, combining search terms of pedicle screw, augmentation, vertebroplasty, kyphoplasty, polymethylmethacrylate, calcium phosphate, or calcium sulfate. The retrieved articles and their references were reviewed, and articles dealing with biomechanical testing were included in this article. Results Polymethylmethacrylate is an effective material for enhancing pedicle screw fixation in both osteoporosis and revision spine surgery models. Several other calcium ceramics also appear promising, although further work is needed in material development. Although fenestrated screw delivery appears to have some benefits, it results in similar screw fixation to prefilling the cement with a solid screw. Some differences in screw biomechanics were noted with varying cement volume and curing time, and some benefits from a kyphoplasty approach over a vertebroplasty approach have been noted. Additionally, in cadaveric models, cemented-augmented screws were able to be removed, albeit at higher extraction torques, without catastrophic damage to the vertebral body. However, there is a risk of cement extravasation leading to potentially neurological or cardiovascular complications with cement use. A major limitation of these reviewed studies is that biomechanical tests were generally performed at screw implantation or after a limited cyclic loading cycle; thus, the results may not be entirely clinically applicable. This is particularly true in the case of the bioactive calcium ceramics, as these biomechanical studies would not have measured the effects of osseointegration. Conclusions Polymethylmethacrylate and various calcium ceramics appear promising for the augmentation of pedicle screw fixation biomechanically in both osteoporosis and revision spine surgery models. Further translational studies should be performed, and the results summarized in this review will need to be correlated with the clinical outcomes.
Purpose
To report outcomes after total en bloc spondylectomy (TES) for primary aggressive/malignant tumors of the lumbar spine.
Methods
We performed a retrospective review of 23 neurosurgical ...patients operated between 2004 and 2014. Outcomes included perioperative complication rates and reoperation rates for instrumentation failure. The relationship between patient/operative parameters and complication development/instrumentation failure was investigated.
Results
There were 15 men (65.2 %) and eight women (24.8 %), with a median of 47 years. The most common tumor was chordoma in 11 patients (47.8 %), followed by sarcoma in four (17.4 %), and giant cell tumor in three (13.0 %). All patients but one underwent a two-staged operation; median total estimated blood loss was 3200 mL and median total operative time was 18.5 h. Fifteen patients developed at least one perioperative complication (65.2 %), with the most common being wound infection and ileus (26.1 % each). There was one case of intraoperative iliac vein injury (4.4 %). Instrumentation failure occurred in 9 patients (39.1 %) at a median time of 23 months after index spondylectomy. Following logistic regression, there were no factors associated with complication development. On the other hand, postoperative radiation was significantly associated with instrumentation failure (OR 7.49; 95 % CI, 1.02–54.9). Local recurrence and 5-year survival was 8.7 and 84.4 %, respectively. Median follow-up time was 50 months.
Conclusions
Although favorable oncological outcomes after en bloc resection of spinal tumors may be achieved in terms of recurrence and survival, TES in the lumbar spine remains a challenging procedure. Future investigation into complication avoidance and reconstruction techniques is encouraged.
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