Giant cell tumor of bone in the pediatric population: a retrospective study highlighting cases of metaphyseal only location and increased local recurrence rates in skeletally immature patients.

OBJECTIVE: To describe the presentation of giant cell tumors (GCT) of the bone in the pediatric population to (1) improve the differential diagnosis of pediatric bone tumors and (2) identify the origin of GCT. Understanding the origin of bone tumors assists in establishing appropriate diagnoses and recommending treatment options. This is particularly important in children, where evaluating the need for invasive procedures is balanced with the desire to avoid overtreatment. GCT have historically been considered epiphyseal lesions with potential metaphyseal extension. Therefore, GCT may be inappropriately excluded from the differential diagnosis of metaphyseal lesions in the skeletally immature. MATERIALS AND METHODS: We identified 14 patients from 1981 to 2021 at a single institution who had histologic confirmation of GCT and were less than 18 years old at diagnosis. Patient characteristics, tumor location, surgical treatment, and local recurrence rates were collected. RESULTS AND CONCLUSIONS: Ten (71%) patients were female. Eleven (78.6%) were epiphysiometaphyseal (1 epiphyseal, 4 metaphyseal, 6 epiphysiometaphyseal). Five patients had an open adjacent physis, of which three (60%) had tumors confined solely to the metaphysis. Of the five patients with open physis, four (80%) developed local recurrence while only one patient (11%) with a closed physis had local recurrence (p value = 0.0023). Our results illustrate that for the skeletally immature, GCT can (and in our results more commonly did) occur in the metaphyseal location. These findings suggest that GCT should be included in the differential diagnosis of primary metaphyseal-only lesions in the skeletally immature.

SARS-CoV-2 Omicron (B.1.1.529) Infection of Wild White-Tailed Deer in New York City.

There is mounting evidence of SARS-CoV-2 spillover from humans into many domestic, companion, and wild animal species. Research indicates that humans have infected white-tailed deer, and that deer-to-deer transmission has occurred, indicating that deer could be a wildlife reservoir and a source of novel SARS-CoV-2 variants. We examined the hypothesis that the Omicron variant is actively and asymptomatically infecting the free-ranging deer of New York City. Between December 2021 and February 2022, 155 deer on Staten Island, New York, were anesthetized and examined for gross abnormalities and illnesses. Paired nasopharyngeal swabs and blood samples were collected and analyzed for the presence of SARS-CoV-2 RNA and antibodies. Of 135 serum samples, 19 (14.1%) indicated SARS-CoV-2 exposure, and 11 reacted most strongly to the wild-type B.1 lineage. Of the 71 swabs, 8 were positive for SARS-CoV-2 RNA (4 Omicron and 4 Delta). Two of the animals had active infections and robust neutralizing antibodies, revealing evidence of reinfection or early seroconversion in deer. Variants of concern continue to circulate among and may reinfect US deer populations, and establish enzootic transmission cycles in the wild: this warrants a coordinated One Health response, to proactively surveil, identify, and curtail variants of concern before they can spill back into humans.

Antibiotic Prophylaxis for Megaprosthetic Reconstructions: Drug and Dosing May Matter More than Duration.

In orthopedic oncology, the implant of a megaprosthetic device is standard of care after large-scale tumor resection involving segmental removal of bone. Infection remains the leading cause of implant failure, often resulting in major morbidity. Perioperative antibiotic practices for megaprosthetic reconstructions are not standardized and are based on guidelines for conventional joint arthroplasties. This study aims to evaluate the efficacy of current prophylactic strategies for megaprosthetic reconstructions. We conducted a retrospective review of megaprosthetic reconstructions performed at Duke University from 2001 to 2021. Logistic regression with GEE was used to assess whether a prolonged course of postoperative antibiotics is associated with infection risk. We assessed the microbial profile and corresponding susceptibilities of megaprosthetic infections through record review. Additionally, we designed a pharmacokinetic subgroup analysis using liquid chromatography-tandem mass spectrometry to quantify antibiotic concentrations in surgical tissue. Wilcoxon rank-sum tests were used to correlate tissue concentrations with infection risk. Out of 184 cases, 23 (12.5%) developed infection within 1 year. Extended postoperative antibiotics were not significantly associated with infection risk (P = 0.23). Among 18 culture-positive cases, 4 (22.2%) were caused by cefazolin-susceptible organisms. Median bone and muscle concentrations of cefazolin among cases that developed postoperative infection (0.065 ng/mL and 0.2 ng/mL, respectively) were significantly lower than those of cases that did not (0.42 ng/mL and 1.95 ng/mL, P < 0.01 and P = 0.03). This study is the first to comprehensively assess aspects of perioperative prophylaxis for megaprosthetic reconstructions. Extending postoperative antibiotics did not reduce infection risk. We detected a high frequency of cefazolin nonsusceptible organisms among postoperative infections. Additionally, intraoperative antibiotic tissue concentrations may be predictive of later infection. Future studies ought to examine optimal drug choices and dosing strategies.

Transmission history of SARS-CoV-2 in humans and white-tailed deer.

The emergence of a novel pathogen in a susceptible population can cause rapid spread of infection. High prevalence of SARS-CoV-2 infection in white-tailed deer (Odocoileus virginianus) has been reported in multiple locations, likely resulting from several human-to-deer spillover events followed by deer-to-deer transmission. Knowledge of the risk and direction of SARS-CoV-2 transmission between humans and potential reservoir hosts is essential for effective disease control and prioritisation of interventions. Using genomic data, we reconstruct the transmission history of SARS-CoV-2 in humans and deer, estimate the case finding rate and attempt to infer relative rates of transmission between species. We found no evidence of direct or indirect transmission from deer to human. However, with an estimated case finding rate of only 4.2%, spillback to humans cannot be ruled out. The extensive transmission of SARS-CoV-2 within deer populations and the large number of unsampled cases highlights the need for active surveillance at the human-animal interface.

Percutaneous Release of Trigger Finger With and Without Steroid Injection A Systematic Review and Meta-Analysis.

PURPOSE: This study sought to determine if concomitant steroid administration with percutaneous release (PRS) of trigger finger leads to better functional outcomes, less postoperative pain, lower rates of trigger recurrence, and lower rates of subsequent open release versus percutaneous release (PR) alone. METHODS: Articles related to trigger finger disorder, percutaneous release of trigger finger, and steroid admin- istration were assessed by two independent reviewers ac- cording to PRISMA guidelines. Data related to satisfaction, pain, disability, recurrence, and need for open release was abstracted from relevant studies. A meta-analysis using random effects models was performed to calculate pooled effect size estimates controlling for heterogeneity between studies. Sensitivity analyses were performed to identify pos- sible sources of heterogeneity between studies. RESULTS: Forty-five studies with a total of 4,188 digits were included in the PR group and seven studies with a total of 700 digits were included in the PRS group. Our meta-analysis showed no significant difference between treatment options with regard to overall satisfaction, postoperative pain, recur- rence rates, or subsequent need for open release. A small difference between groups was observed in postoperative disability, with lower levels of disability following PRS versus PR. CONCLUSIONS: Based on current literature, both PR and PRS are safe and effective treatments for trigger finger. Steroid administration with percutaneous release may lead to lower rates of postoperative disability, but due to the small difference observed and the modest sample size of studies that examined this outcome, further studies are needed to elucidate if the difference seen in disability is clinically relevant.

Detection of SARS-CoV-2 Omicron variant (B.1.1.529) infection of white-tailed deer.

White-tailed deer ( Odocoileus virginianus ) are highly susceptible to infection by SARS-CoV-2, with multiple reports of widespread spillover of virus from humans to free-living deer. While the recently emerged SARS-CoV-2 B.1.1.529 Omicron variant of concern (VoC) has been shown to be notably more transmissible amongst humans, its ability to cause infection and spillover to non-human animals remains a challenge of concern. We found that 19 of the 131 (14.5%; 95% CI: 0.10-0.22) white-tailed deer opportunistically sampled on Staten Island, New York, between December 12, 2021, and January 31, 2022, were positive for SARS-CoV-2 specific serum antibodies using a surrogate virus neutralization assay, indicating prior exposure. The results also revealed strong evidence of age-dependence in antibody prevalence. A significantly (χ 2 , p < 0.001) greater proportion of yearling deer possessed neutralizing antibodies as compared with fawns (OR=12.7; 95% CI 4-37.5). Importantly, SARS-CoV-2 nucleic acid was detected in nasal swabs from seven of 68 (10.29%; 95% CI: 0.0-0.20) of the sampled deer, and whole-genome sequencing identified the SARS-CoV-2 Omicron VoC (B.1.1.529) is circulating amongst the white-tailed deer on Staten Island. Phylogenetic analyses revealed the deer Omicron sequences clustered closely with other, recently reported Omicron sequences recovered from infected humans in New York City and elsewhere, consistent with human to deer spillover. Interestingly, one individual deer was positive for viral RNA and had a high level of neutralizing antibodies, suggesting either rapid serological conversion during an ongoing infection or a "breakthrough" infection in a previously exposed animal. Together, our findings show that the SARS-CoV-2 B.1.1.529 Omicron VoC can infect white-tailed deer and highlights an urgent need for comprehensive surveillance of susceptible animal species to identify ecological transmission networks and better assess the potential risks of spillback to humans. KEY FINDINGS: These studies provide strong evidence of infection of free-living white-tailed deer with the SARS-CoV-2 B.1.1.529 Omicron variant of concern on Staten Island, New York, and highlight an urgent need for investigations on human-to-animal-to-human spillovers/spillbacks as well as on better defining the expanding host-range of SARS-CoV-2 in non-human animals and the environment.

Multiple spillovers from humans and onward transmission of SARS-CoV-2 in white-tailed deer.

Many animal species are susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and could act as reservoirs; however, transmission in free-living animals has not been documented. White-tailed deer, the predominant cervid in North America, are susceptible to SARS-CoV-2 infection, and experimentally infected fawns can transmit the virus. To test the hypothesis that SARS-CoV-2 is circulating in deer, 283 retropharyngeal lymph node (RPLN) samples collected from 151 free-living and 132 captive deer in Iowa from April 2020 through January of 2021 were assayed for the presence of SARS-CoV-2 RNA. Ninety-four of the 283 (33.2%) deer samples were positive for SARS-CoV-2 RNA as assessed by RT-PCR. Notably, following the November 2020 peak of human cases in Iowa, and coinciding with the onset of winter and the peak deer hunting season, SARS-CoV-2 RNA was detected in 80 of 97 (82.5%) RPLN samples collected over a 7-wk period. Whole genome sequencing of all 94 positive RPLN samples identified 12 SARS-CoV-2 lineages, with B.1.2 (n = 51; 54.5%) and B.1.311 (n = 19; 20%) accounting for ∼75% of all samples. The geographic distribution and nesting of clusters of deer and human lineages strongly suggest multiple human-to-deer transmission events followed by subsequent deer-to-deer spread. These discoveries have important implications for the long-term persistence of the SARS-CoV-2 pandemic. Our findings highlight an urgent need for a robust and proactive "One Health" approach to obtain enhanced understanding of the ecology, molecular evolution, and dissemination of SARS-CoV-2.

Variability in the reported surgical techniques and methods for intercalary reconstruction following tumor resection.

INTRODUCTION: There is currently no consensus regarding the best techniques or surgical strategies with which to maximize intercalary allograft reconstruction outcomes. The purpose of the current study was to assess which techniques and methods are being utilized by North American orthopaedic oncologists. METHODS: Members of the Musculoskeletal Tumor Society (MSTS) were invited to complete an anonymous online questionnaire. The survey presented participants with two clinical scenarios and interrogated them on their preferred type of allograft, method of compression and fixation, and additional techniques used. RESULTS: One hundred and twenty-six physicians completed the questionnaire. The majority studied in the United States (82%) and worked at an academic medical center (71%). Over half (54%) reported seeing over 10 primary bone tumors every year. Respondents were split between preferring a structural allograft alone or using a combined allograft-vascularized fibular graft. A majority indicated a preference for plate(s) and screw fixation but were divided between the use of two compression plates with a spanning plate, a single compression plate with a spanning plate, and two compression plates with an intramedullary nail. Screw fixation preferences were split between the use of unicortical locking only, bicortical locking only, and a combination of unicortical and bicortical locking. Almost equal percentages of respondents reported they would have used two, three, or four screws in both scenarios. Respondents were split between placing screws equidistantly and placing them peripherally within the allograft, adjacent to the allograft-host junction. DISCUSSION: There is no clear surgical preference for intercalary reconstruction following tumor extirpation within this sample of orthopaedic oncologists. The current survey demonstrates variability across nearly every aspect of allograft reconstruction, which may, in part, explain the wide spectrum of outcomes reported within the literature. Prospective studies are warranted to better evaluate technique-specific outcomes in an effort to maximize reconstructive longevity and minimize allograft related complications.

Comparing Surgical Treatments for Spondylolysis: Review on Current Research.

STUDY DESIGN: Narrative review. OBJECTIVE: To compare the various surgical methods of repairing spondylolysis defects in regard to improving pain, restoration of function, radiographic improvement, and complication rate. SUMMARY OF BACKGROUND DATA: Spondylolysis is a defect in the pars interarticularis of the vertebral arch, typically in the lumbar vertebra. Treatment can be nonoperative and/or surgical. There are various types of surgical repair including spinal compression, fusion, and direct pars repair. METHODS: A comprehensive review of the English literature was performed utilizing Medline, Embase, and Web of Science. Inclusion criteria included papers or abstracts that evaluated the surgical techniques. Exclusion criteria included non-English-language papers or abstracts with inadequate information about outcomes. RESULTS: Postoperative pain levels and patient function were consistently improved, regardless of surgical technique chosen. Positive clinical outcomes after surgery were seen more often in patients under age 20 and those who underwent minimally invasive repairs. Positive radiographic improvements were reported broadly, although some reported higher rates of nonunion with spinal compression. Complication rates were low throughout and minimally invasive techniques reported decreased blood loss and shorter hospital stays. CONCLUSIONS: Present surgical options appear largely comparable in terms of their ability to provide meaningful treatment for spondylolysis where conservative treatments have failed or otherwise remain unattempted.

Systematic Review of Outcomes Following 10-Year Mark of Spine Patient Outcomes Research Trial (SPORT) for Degenerative Spondylolisthesis.

STUDY DESIGN: We performed a comprehensive search of PubMed, MEDLINE, and EMBASE for all English language studies of all levels of evidence pertaining to Spine Patient Outcomes Research Trial (SPORT), in accordance with Preferred Reported Items for Systematic Reviews and Meta-analyses guidelines. OBJECTIVE: We aim to summarize the 10-year clinical outcomes of SPORT and its numerous follow-up studies for degenerative spondylolisthesis. SUMMARY OF BACKGROUND DATA: The SPORT was a landmark randomized control trial including approximately 2500 patients at 13 clinics across the country. SPORT compared surgical and nonoperative management of the three most common spinal pathologies. METHODS: Keywords used in the literature search included SPORT, spine patient outcomes research trial, degenerative spondylolisthesis, and surgical outcomes. RESULTS: The intent-to-treat analysis failed to show a significant difference between patients treated surgically as compared to those treated nonoperatively. However, as-treated analysis revealed statically greater improvements at 6 weeks, 2 years, and 4 years in patients treated surgically. Secondary outcomes such as low back pain, leg pain, stenosis bothersome scales, overall satisfaction with current symptoms, and self-rated progress were also significantly improved in surgical patients. Regardless of the initial grade of listhesis, disk height, or mobility, patients who had surgical treatment improved more in terms of Oswestry Disability Index, bodily pain, physical function, and low back pain bothersomeness scales. Risk of reoperation increased with age, having two or three moderate or severe stenotic levels, pain predominantly localized to the back, no physical therapy, the absence of neurogenic claudication, and greater leg pain scores. Risk of reoperation was not significantly affected by type of surgery performed, smoking, diabetes, obesity, longer duration of symptoms, or workman's compensation. CONCLUSION: Although intent-to-treat analysis failed to show significant differences in patients treated surgically, results of the as-treated analysis determined statically greater improvements in those patients with spondylolisthesis who were treated surgically as compared to those treated nonoperatively. LEVEL OF EVIDENCE: 2.

Systematic Review of Outcomes Following 10-Year Mark of Spine Patient Outcomes Research Trial for Intervertebral Disc Herniation.

MINI: We summarized the 10-year outcomes of Spine Patient Outcomes Research Trial for intervertebral disc herniation through a systematic review. The observational cohort 2-year analysis and the as-treated analysis of the randomized control trial at 4 and 8 years showed statistically greater improvements in those patients who were treated surgically. STUDY DESIGN: We performed a comprehensive search of Pubmed, MEDLINE, and EMBASE for English-language studies of all levels of evidence pertaining to SPORT, in accordance with Preferred Reported Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. OBJECTIVE: We aim to summarize the 10-year clinical outcomes of SPORT and its numerous follow-up studies for intervertebral disc herniation. SUMMARY OF BACKGROUND DATA: The Spine Patient Outcomes Research Trial (SPORT) was a landmark study. SPORT compared surgical and nonoperative management of the three most common spinal pathologies. METHODS: Keywords utilized included: SPORT, spine patient outcomes research trial, disc herniation, and surgical outcomes. RESULTS: The observational cohort analysis revealed statically greater improvement in primary outcomes at 3 months and 2 years in patients who had surgery, while analysis of the randomized control trial cohort failed to show a significant difference based on the intent-to-treat principle due to significant patient crossover. However, 4 year and 8 year as-treated analysis showed statistically greater improvements in those patients who were treated surgically. SPORT's subgroup analysis evaluated important factors when considering the treatment of IDH, including patient characteristics, level of herniation, duration of symptoms, recurrence of pain, presence of retrolistheiss, patient functional status, effects of previous treatment with epidural steroid injections and opioid medication, outcomes after incidental durotomy, MRI reader reliability, reoperation rates, and risk factors for reoperation. The clinical impact of SPORT was also investigated and included comparison of SPORT patients to NSQIP patients to determine generalizability, outcome differences in SPORT's surgical center sites, patient preferences, patient expectations, level of education, and effects of watching an evidence-based video. CONCLUSION: Ten years after its inception, SPORT has made strides in standardization and optimization of treatment for spinal pathologies. SPORT has provided clinicians with insight about outcomes of surgical and nonoperative treatment of IDH. Results showed significantly greater improvements in patients treated surgically. LEVEL OF EVIDENCE: 3.

We performed a comprehensive search of Pubmed, MEDLINE, and EMBASE for English-language studies of all levels of evidence pertaining to SPORT, in accordance with Preferred Reported Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We aim to summarize the 10-year clinical outcomes of SPORT and its numerous follow-up studies for intervertebral disc herniation. The Spine Patient Outcomes Research Trial (SPORT) was a landmark study. SPORT compared surgical and nonoperative management of the three most common spinal pathologies. Keywords utilized included: SPORT, spine patient outcomes research trial, disc herniation, and surgical outcomes. The observational cohort analysis revealed statically greater improvement in primary outcomes at 3 months and 2 years in patients who had surgery, while analysis of the randomized control trial cohort failed to show a significant difference based on the intent-to-treat principle due to significant patient crossover. However, 4 year and 8 year as-treated analysis showed statistically greater improvements in those patients who were treated surgically. SPORT's subgroup analysis evaluated important factors when considering the treatment of IDH, including patient characteristics, level of herniation, duration of symptoms, recurrence of pain, presence of retrolistheiss, patient functional status, effects of previous treatment with epidural steroid injections and opioid medication, outcomes after incidental durotomy, MRI reader reliability, reoperation rates, and risk factors for reoperation. The clinical impact of SPORT was also investigated and included comparison of SPORT patients to NSQIP patients to determine generalizability, outcome differences in SPORT's surgical center sites, patient preferences, patient expectations, level of education, and effects of watching an evidence-based video. Ten years after its inception, SPORT has made strides in standardization and optimization of treatment for spinal pathologies. SPORT has provided clinicians with insight about outcomes of surgical and nonoperative treatment of IDH. Results showed significantly greater improvements in patients treated surgically. Level of Evidence: 3.

Systematic Review of Outcomes Following 10-year Mark of Spine Patient Outcomes Research Trial (SPORT) for Spinal Stenosis.

STUDY DESIGN: We performed a comprehensive search of Pubmed, MEDLINE, and EMBASE for all English-language studies of all levels of evidence pertaining to SPORT, in accordance with Preferred Reported Items for Systematic Reviews and Meta-analayses (PRISMA) guidelines. OBJECTIVE: We aim to summarize the 10-year clinical outcomes of SPORT and its numerous follow-up studies for spinal stenosis. SUMMARY OF BACKGROUND DATA: The Spine Patient Outcomes Research Trial (SPORT) was a landmark randomized control trial including approximately 2,500 patients at 13 clinics across the country. SPORT compared surgical and nonoperative management of the three most common spinal pathologies. METHODS: Keywords utilized in the literature search included: SPORT, spine patient outcomes research trial, spinal stenosis, and surgical outcomes. RESULTS: Surgical intervention showed significantly greater improvement in pain and physical function scales from 6 weeks through 4 years. However, between 4 and 8 years, the difference between the two groups diminished, and the benefits in both groups stabilized. Secondary factors investigated showed that smoking was a confounding variable for treatment benefits and a positive sedimentation sign correlated with a greater surgical treatment effect. Obese patients were found to have higher rates of infection and reoperation and less improvement from baseline function. Risk factors for reoperation included duration of pretreatment symptoms for longer than 12 months, increased age, multiple levels of stenosis, predominant back pain, no physical therapy, greater leg pain, the use of antidepressants and no neurogenic claudication upon enrollment. CONCLUSION: Ten years after its inception, SPORT has made strides in standardization and optimization of treatment for spinal pathologies. SPORT has provided clinicians with insight about outcomes of surgical and nonoperative treatment of spinal stenosis. Results showed significantly greater improvement through 4 year follow up in those patients that received surgical treatment, however the difference between the surgical and nonsurgical groups diminished at 8 year follow up. LEVEL OF EVIDENCE: 3.

LigaSure Use Decreases Intraoperative Blood Loss Volume and Blood Transfusion Volume in Sarcoma Surgery.

INTRODUCTION: The LigaSure system has been successfully used in thoracic and abdominal surgery. However, to date, its use in the resection of sarcomas has not been systematically studied. We aimed to determine whether the use of the LigaSure system reduces blood loss and blood transfusion volumes in sarcoma surgery. METHODS: One hundred forty-two consecutive patients who underwent sarcoma surgeries between July 2010 and October 2016 were included. Conventional electrocautery alone (n = 91) and with LigaSure (n = 51) were compared. Case-matched samples (n = 46) from each group were additionally compared. RESULTS: The use of the LigaSure system resulted in a significant decrease in mean intraoperative blood loss (P = 0.02) and blood transfusion volume (P = 0.04). Likewise, a significant decrease in both mean and median intraoperative blood loss (P = 0.003; P < 0.0001) was seen with LigaSure in the case-matched analysis. In the soft-tissue sarcoma subgroup, a significant decrease was observed in mean hemoglobin reduction (P = 0.03) and mean intraoperative blood loss with LigaSure (P = 0.04). No adverse perioperative complications attributed to the LigaSure system were identified. CONCLUSIONS: The LigaSure vessel sealing and dividing system is a safe and effective hemostatic tool for deep dissection in bone and soft-tissue sarcoma surgery. LEVEL OF EVIDENCE: Level III, therapeutic study.

A review of lumbosacral transitional vertebrae and associated vertebral numeration.

PURPOSE: To review the current literature on methods of accurate numeration of vertebral segments in patients with Lumbosacral transitional vertebrae (LSTVs). LSTVs are a common congenital anomaly of the L5-S1 junction. While their clinical significance has been debated, unquestionable is the need for their identification prior to spinal surgery. We hypothesize that there are no reliable landmarks by which we can accurately number transitional vertebrae, and thus a full spinal radiograph is required. METHODS: A Pubmed and EMBASE search using various combinations of specific key words including "LSTV", "lumbosacral transitional vertebrae", "count", "vertebral numbering", and "number" was performed. RESULTS: The gold standard for spinal segment numeration in patients with LSTV remains whole spine imaging and counting caudally, starting from C2. If whole spine imaging is not available, the use of the iliac crest tangent sign on coronal magnetic resonance imaging (MRI) has fairly reliable sensitivity and specificity (81 and 64-88%, respectively) for accurate numeration of LSTV. The role of paraspinal anatomic markers such as the right renal artery, superior mesenteric artery, aortic bifurcation, and conus medullaris, for identification of vertebral levels is unreliable and should not be used. CONCLUSIONS: A sagittal whole spine view should be added as a scout view when patients obtain lumbar MRI to standardize the vertebral numbering technique. To date, there has been no other method for accurate numeration of a transitional vertebral segment, other than counting caudally from C2. These slides can be retrieved under Electronic Supplementary Material.