Diffusivity of Human Cartilage Endplates in Healthy and Degenerated Intervertebral Disks.

The cartilage endplates (CEPs) on the superior and inferior surfaces of the intervertebral disk (IVD), are the primary nutrient transport pathways between the disk and the vertebral body. Passive diffusion is responsible for transporting small nutrient and metabolite molecules through the avascular CEPs. The baseline solute diffusivities in healthy CEPs have been previously studied, however alterations in CEP diffusion associated with IVD degeneration remain unclear. This study aimed to quantitatively compare the solute diffusion in healthy and degenerated human CEPs using a fluorescence recovery after photobleaching (FRAP) approach. Seven healthy CEPs and 22 degenerated CEPs were collected from five fresh-frozen human cadaveric spines and 17 patients undergoing spine fusion surgery, respectively. The sodium fluorescein diffusivities in CEP radial and vertical directions were measured using the FRAP method. The CEP calcification level was evaluated by measuring the average X-ray attenuation. No difference was found in solute diffusivities between radial and axial directions in healthy and degenerated CEPs. Compared to healthy CEPs, the average solute diffusivity was 44% lower in degenerated CEPs (Healthy: 29.07 µm2/s (CI: 23.96-33.62 µm2/s); degenerated: 16.32 µm2/s (CI: 13.84-18.84 µm2/s), p < 0.001). The average solute diffusivity had an inverse relationship with the degree of CEP calcification as determined by the normalized X-ray attenuation values (ß = -22.19, R2 = 0.633; p < 0.001). This study suggests that solute diffusion through the disk and vertebral body interface is significantly hindered by CEP calcification, providing clues to help further understand the mechanism of IVD degeneration.

Quantitative Analysis of Cervical Flexion-Extension Radiographs in Rheumatoid Arthritis Patients.

STUDY DESIGN: Diagnostic retrospective case series. OBJECTIVE: To evaluate cervical intersegmental motion in rheumatoid arthritis patients using specialized tracking software (QMA) and compare the findings with a previously published cohort of "normal" subjects. SUMMARY OF BACKGROUND DATA: Rheumatoid arthritis follows 3 patterns of cervical involvement, atlantoaxial subluxation, atlantoaxial impaction, and subaxial subluxation. Deformities present are sometimes considered "unstable" to the point where surgery can be recommended based on the interpretation of cervical radiographs. METHODS: Cervical flexion-extension radiographs of 99 subjects with rheumatoid arthritis were evaluated. Angular and translational segmental motions were determined at each level using specialized tracking software. Findings were compared with previously published normative data using the same device. RESULTS: Relative to controls, patients with rheumatoid arthritis demonstrated significantly less overall sagittal motion. Segmental analysis at C1-C2 demonstrated a 10% prevalence of dynamic motion outside the 95% confidence interval for "normal" patients. In contrast, segmental analysis at C2-C7 demonstrated no intersegmental motion outside the 95% confidence interval for "normal" subjects. CONCLUSIONS: In patients with rheumatoid arthritis, abnormal motion at C1-C2 was consistent with truly dynamic deformity and should be closely evaluated. Conversely, subaxial subluxations, although frequently present, were relatively fixed deformities and in most cases, may not represent an unstable condition.

Efficacy of MRI for assessment of spinal trauma: correlation with intraoperative findings.

STUDY DESIGN: Observational diagnostic study on consecutive patients. OBJECTIVE: To assess the efficacy of magnetic resonance imaging (MRI) for detecting spinal soft tissue injury after acute trauma using intraoperative findings as a reference standard. SUMMARY OF BACKGROUND DATA: Recognizing injuries to spinal soft tissue structures is critical for proper decision making and management for blunt trauma victims. Although MRI is considered the gold standard for imaging of soft tissues, its ability to identify specific components of soft tissue damage in acute spine trauma patients is poorly documented and controversial. METHODS: Intraoperative findings were recorded for 21 acute spinal trauma patients (study group) and 14 nontraumatic spinal surgery patients (control group). Preoperative MRI's were evaluated randomly and blindly by 2 neuroradiologists. MRI and intraoperative findings were compared. By using the intraoperative findings as the reference standard, sensitivity, specificity, positive and negative predictive values of MRI in detecting spinal soft tissue injury were determined. RESULTS: MRI was 100% sensitive and specific in detecting injury to the anterior longitudinal ligament. MRI was moderately sensitive (80%) but highly specific (100%) for injury to the posterior longitudinal ligament. In contrast, MRI was highly sensitive but less specific in detecting injury to paraspinal muscles (100%, 77%), intervertebral disk (100%, 71%), and interspinous ligament (100%, 64%). MRI was moderately sensitive and specific in detecting ligamentum flavum injury (80% and 86.7%) but poorly sensitive for facet capsule injury (62.5%). CONCLUSIONS: MRI demonstrated high sensitivity for spinal soft tissue injuries. However, MRI showed a definite trend to overestimate interspinous ligament, intervertebral disk, and paraspinal muscle injuries. On the basis of these results, we would consider MRI to be a useful tool for spine clearance after trauma. Conversely, caution should be applied when using MRI for operative decision making due to its less predictable specificity.

Establishing case volume benchmarks for ACGME-accredited orthopedic surgery of the spine fellowship training.

BACKGROUND CONTEXT: There has been increasing scrutiny on the standardization of surgical training in the US. PURPOSE: This study provides case volume benchmarks for Accreditation Council for Graduate Medical Education (ACGME)-accredited orthopedic spine surgery fellowship training. STUDY DESIGN/SETTING: This was a retrospective cross-sectional study of fellows at ACGME-accredited orthopedic spine surgery fellowships (2017-2022). PATIENT SAMPLE: N/A. OUTCOME MEASURES: Reported case volume during fellowship training. METHODS: Case volume percentiles were calculated across ACGME-defined case categories and temporal changes assessed via linear regression. Variability between the highest and lowest deciles by case volume was calculated as fold-differences (90th percentile/10th percentile). Sensitivity analyses were performed to identify potential targets for case minimum requirements. RESULTS: A total of 163 spine surgery fellows were included in this study. Total mean reported spine surgery case volume increased from 313.2±122 in 2017 to 382.0±164 in 2022 (p=.19). Most cases were classified as adult (range, 97.2%-98.0%) over pediatric cases (range, 2.0%-2.8%). An average of 322.0 cases were reported and most were classified as laminectomy (32%), posterior arthrodesis (29%), and anterior arthrodesis (20%). Overall variability in total case volume was 2.4 and the greatest variability existed for posterior instrumentation (38.1), application of cage (34.6), anterior instrumentation (20.8), and fractures and dislocations (17.3). If case minimum requirements for total reported cases was assumed at 200 cases, then all spine fellows included in this study would achieve this requirement. However, if case minimum requirements were assumed at 250 total cases, then approximately thirty percent of fellows (n=49) would not achieve this requirement for graduation. CONCLUSIONS: Increasingly, national societies and accrediting bodies for surgical education recognize the need for standardized training. This study provides benchmarks to inform potential case minimum requirements and help reduce variability during spine fellowship training. Future studies are needed to establish case minimum requirements for spine surgery fellowship training across comprehensive and granular case categories that cover the full gamut of orthopedic spine surgery.

A cadaver study to compare vertebral augmentation with a high-viscosity cement to augmentation with conventional lower-viscosity cement.

STUDY DESIGN: Comparison of extravasations in fractured cadaver vertebrae augmented with commercial low-viscosity versus high-viscosity cements. OBJECTIVE: Use of high-resolution, 3-dimensional (3D) imaging to test the hypothesis that high-viscosity cements can reduce the type and severity of extravasations after vertebral augmentation procedures. SUMMARY OF BACKGROUND DATA: Cement extravasations are one of the primary complications of vertebral augmentation procedures. There is some evidence that high-viscosity cements might reduce extravasations, but additional data are needed to confirm the early findings. METHODS: A range of vertebral fractures were created in fresh human cadavers. One group was then augmented with a low-viscosity polymethylmethacrylate (PMMA)-based cement and the other group injected with high-viscosity PMMA-based cement. High-resolution computerized tomography exams were obtained, and extravasations were assessed using 3D volume renderings. The type and severity of extravasations were recorded and analyzed. RESULTS: The proportion of vertebrae with any type of extravasation through the posterior wall to the spinal canal, into small vessels laterally or anteriorly, through the endplates, or anywhere around the body was not significantly different between the high-viscosity and low-viscosity groups. There was significantly less severe extravasation through the endplates (P=0.02), and a trend toward less severe extravasation through vessels (P=0.06) with the high versus low-viscosity cements. CONCLUSIONS: In agreement with previous research, high-viscosity PMMA-based cement may help to reduce the more severe forms of extravasations after vertebral augmentation procedures in newly fractured vertebrae.

Osteology of the coronoid process with clinical correlation to coronoid fractures in terrible triad injuries.

BACKGROUND: Terrible triad complex elbow fracture-dislocations are represented by elbow dislocations associated with fractures of the coronoid and radial head. Published literature has focused on classifying coronoid fractures by their radiographic morphology on plain x-ray images and computed tomography imaging. No study has specifically related native coronoid osteology to in situ fracture morphology. We identified 3 distinct bony regions of the coronoid, (medial, intermediate, and lateral ridges) with correlation to common fracture patterns associated with terrible triad injuries. METHODS: Coronoid osteology in 8 fresh frozen cadaveric elbows was examined, and three distinct ridges were identified and dimensions measured. RESULTS: The measurements were compared with retrospective intraoperative measurements taken of coronoid fracture fragments being stabilized during terrible triad injury repair. CONCLUSION: Classification of native coronoid process anatomy into functional ridges (medial, intermediate, lateral) may improve our understanding of coronoid fracture patterns in unstable terrible triad injuries. LEVEL OF EVIDENCE: Basic Science, Anatomic Study, Cadaver and In Vivo.

Opioid Use Patterns in a Statewide Adult Medicaid Population Undergoing Elective Lumbar Spine Surgery.

STUDY DESIGN: Retrospective administrative database review. OBJECTIVE: Analyze patterns of opioid use in patients undergoing lumbar surgery and determine associated risk factors in a Medicaid population. SUMMARY OF BACKGROUND DATA: Opioid use in patients undergoing surgery for degenerative lumbar spine conditions is prevalent and impacts outcomes. There is limited information defining the scope of this problem in Medicaid patients. MATERIALS AND METHODS: Longitudinal cohort study of adult South Carolina (SC) Medicaid patients undergoing lumbar surgery from 2014 to 2017. All patients had continuous SC Medicaid coverage for 15 consecutive months, including six months before and nine months following surgery. The primary outcome was a longitudinal assessment of postoperative opioid use to determine trajectories and group-based membership using latent modeling. Univariate and multivariable modeling was conducted to assess risk factors for group-based trajectory modeling and chronic opioid use (COU). RESULTS: A total of 1455 surgeries met inclusion criteria. Group-based trajectory model demonstrated patients fit into five groups; very low use (23.4%), rapid wean following surgery (18.8%), increasing use following surgery (12.9%), slow wean following surgery (12.6%) and sustained high use (32.2%). Variables predicting membership in high opioid use included preoperative opioid use, younger age, longer length of stay, concomitant medications, and readmissions. More than three quarter of patients were deemed COUs (76.4%). On bivariate analysis, patients with degenerative disk disease were more likely to be COUs (24.8% vs. 18.6%; P =0.0168), more likely to take opioids before surgery (88.5% vs. 61.9%; P <0.001) and received higher amounts of opioids during the 30 days following surgery (mean morphine milligram equivalents 59.6 vs. 25.1; P <0.001). CONCLUSIONS: Most SC Medicaid patients undergoing lumbar elective lumbar spine surgery were using opioids preoperatively and continued long-term use postoperatively at a higher rate than previously reported databases. Preoperative and perioperative intake, degenerative disk disease, multiple prescribers, depression, and concomitant medications were significant risk factors.

In vitro analysis of polymer candidates for the development of absorbable vascular filters.

PURPOSE: To test absorbable materials as a prelude to development of an absorbable vena cava filter for the prevention of pulmonary embolism (PE). MATERIALS AND METHODS: Three absorbing polymer candidates, poliglecaprone (Monocryl; sizes 4-0 and 1), polyglactin (Vicryl; sizes 4-0 and 1), and polydioxanone (PDSII; sizes 4-0, 2-0, 0, and 1), were fabricated into vascular filters and evaluated in an engineered closed circulation system that replicated human physiologic characteristics. Material performance was determined over a period of 10 weeks via weekly tensile testing, yielding stress-versus-strain parameters. Control samples of the same absorbable polymers were also tested in a static buffer. RESULTS: PDSII (size 2-0) retained 69% strength in circulation versus 86% in control at 6 weeks (P < .0001) and 11% strength in circulation versus 51% in control at 10 weeks (P < .001). It was fully absorbed in circulation by 22 weeks. In contrast, Monocryl and Vicryl absorbed much faster, with Monocryl possessing 6% strength at 2 weeks in circulation and Vicryl reaching 0% strength at 4 weeks. CONCLUSIONS: Polydioxanone appears to be a strong candidate for novel absorbable vascular filters for PE prevention, with sufficient strength retention to catch emboli for at least 6 weeks and sequentially absorb via hydrolysis into CO(2) and H(2)O within 22 weeks.

Radial styloid fractures.

Radial styloid fractures can occur in isolation or in association with other injuries, including complex intra-articular distal radius fractures, carpal fractures, carpal dislocations, and radiocarpal dislocations. The anatomy surrounding the radial styloid is complex, and complications related to surgical approach, treatments, and symptomatic hardware can occur. Operative treatments vary according to the injury pattern present, and pattern recognition is the key to optimizing treatment of these injuries. Outcomes are related to the precision of the reconstruction as well as the magnitude of the injury; better results are associated with lower-energy patterns.

Definition of Normal Vertebral Morphometry Using NHANES-II Radiographs.

A robust definition of normal vertebral morphometry is required to confidently identify abnormalities such as fractures. The Second National Health and Nutrition Examination Survey (NHANES-II) collected a nationwide probability sample to document the health status of the United States. Over 10,000 lateral cervical spine and 7,000 lateral lumbar spine X-rays were collected. Demographic, anthropometric, health, and medical history data were also collected. The coordinates of the vertebral body corners were obtained for each lumbar and cervical vertebra using previously validated, automated technology consisting of a pipeline of neural networks and coded logic. These landmarks were used to calculate six vertebral body morphometry metrics. Descriptive statistics were generated and used to identify and trim outliers from the data. Descriptive statistics were tabulated using the trimmed data for use in quantifying deviation from average for each metric. The dependency of these metrics on sex, age, race, nation of origin, height, weight, and body mass index (BMI) was also assessed. There was low variation in vertebral morphometry after accounting for vertebrae (eg, L1, L2), and the R 2 was high for ANOVAs. Excluding outliers, age, sex, race, nation of origin, height, weight, and BMI were statistically significant for most of the variables, though the F-statistic was very small compared to that for vertebral level. Excluding all variables except vertebra changed the ANOVA R 2 very little. Reference data were generated that could be used to produce standardized metrics in units of SD from mean. This allows for easy identification of abnormalities resulting from vertebral fractures, atypical vertebral body morphometries, and other congenital or degenerative conditions. Standardized metrics also remove the effect of vertebral level, facilitating easy interpretation and enabling data for all vertebrae to be pooled in research studies. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Management of degenerative spondylolisthesis: development of appropriate use criteria.

BACKGROUND CONTEXT: Outcomes of treatment in care of patients with spinal disorders are directly related to patient selection and treatment indications. However, for many disorders, there is absence of consensus for precise indications. With the increasing emphasis on quality and value in spine care, it is essential that treatment recommendations and decisions are optimized. PURPOSE: The purpose of the North American Spine Society Appropriate Use Criteria was to determine the appropriate (ie reasonable) multidisciplinary treatment recommendations for patients with degenerative spondylolisthesis across a spectrum of more common clinical scenarios. STUDY DESIGN: A Modified Delphi process was used. METHODS: The methodology was based on the Appropriate Use Criteria development process established by the Research AND Development Corporation. The topic of degenerative spondylolisthesis was selected by the committee, key modifiers determined, and consensus reached on standard definitions. A literature search and evidence analysis were completed by one work group simultaneously as scenarios were written, reviewed, and finalized by another work group. A separate multidisciplinary rating group was assembled. Based on the literature, provider experience, and group discussion, each scenario was scored on a nine-point scale on two separate occasions, once without discussion and then a second time following discussion based on the initial responses. The median rating for each scenario was then used to determine if indications were rarely appropriate (1 - 3), uncertain (4-6), or appropriate (7-9). Consensus was not mandatory. RESULTS: There were 131 discrete scenarios. These addressed questions on bone grafting, imaging, mechanical instability, radiculopathy with or without neurological deficits, obesity, and yellow flags consisting of psychosocial and medical comorbidities. For most of these, appropriateness was established for physical therapy, injections, and various forms of surgical intervention. The diagnosis of spondylolisthesis should be determined by an upright x-ray. Scenarios pertaining to bone grafting suggested that patients should quit smoking prior to surgery, and that use of BMP should be reserved for patients who had risk factors for non-union. Across all clinical scenarios, physical therapy (PT) had an adjusted mean of 7.66, epidural steroid injections 5.76, and surgery 4.52. Physical therapy was appropriate in most scenarios, and most appropriate in patients with back pain and no neurological deficits. Epidural steroid injections were most appropriate in patients with radiculopathy. Surgery was generally more appropriate for patients with neurological deficits, higher disability scores, and dynamic spondylolisthesis. Mechanical back pain and presence of yellow flags tended to be less appropriate, and obesity in general had relatively little influence on decision making. Decompression alone was more strongly considered in the presence of static versus dynamic spondylolisthesis. On average, posterior fusion with or without interbody fusion was similarly appropriate, and generally more appropriate than stand-alone interbody fusion which was in turn more appropriate than interspinous spacers. CONCLUSIONS: Multidisciplinary appropriate treatment criteria were generated based on the Research AND Development methodology. While there were consistent and significant differences between surgeons and non-surgeons, these differences were generally very small. This document provides comprehensive evidence-based recommendations for evaluation and treatment of degenerative spondylolisthesis. The document in its entirety will be found on the North American Spine Society website (https://www.spine.org/Research-Clinical-Care/Quality-Improvement/Appropriate-Use-Criteria).

Cervical fusion for treatment of degenerative conditions: development of appropriate use criteria.

BACKGROUND CONTEXT: High quality evidence is difficult to generate, leaving substantial knowledge gaps in the treatment of spinal conditions. Appropriate use criteria (AUC) are a means of determining appropriate recommendations when high quality evidence is lacking. PURPOSE: Define appropriate use criteria (AUC) of cervical fusion for treatment of degenerative conditions of the cervical spine. STUDY DESIGN/SETTING: Appropriate use criteria for cervical fusion were developed using the RAND/UCLA appropriateness methodology. Following development of clinical guidelines and scenario writing, a one-day workshop was held with a multidisciplinary group of 14 raters, all considered thought leaders in their respective fields, to determine final ratings for cervical fusion appropriateness for various clinical situations. OUTCOME MEASURES: Final rating for cervical fusion recommendation as either "Appropriate," "Uncertain" or "Rarely Appropriate" based on the median final rating among the raters. METHODS: Inclusion criteria for scenarios included patients aged 18 to 80 with degenerative conditions of the cervical spine. Key modifiers were defined and combined to develop a matrix of clinical scenarios. The median score among the raters was used to determine the final rating for each scenario. The final rating was compared between modifier levels. Spearman's rank correlation between each modifier and the final rating was determined. A multivariable ordinal regression model was fit to determine the adjusted odds of an "Appropriate" final rating while adjusting for radiographic diagnosis, number of levels and symptom type. Three decision trees were developed using decision tree classification models and variable importance for each tree was computed. RESULTS: Of the 263 scenarios, 47 (17.9 %) were rated as rarely appropriate, 66 (25%) as uncertain and 150 (57%) were rated as appropriate. Symptom type was the modifier most strongly correlated with the final rating (adjusted ρ2 = 0.58, p<.01). A multivariable ordinal regression adjusting for symptom type, diagnosis, and number of levels and showed high discriminative ability (C statistic = 0.90) and the adjusted odds ratio (aOR) of receiving a final rating of "Appropriate" was highest for myelopathy (aOR, 7.1) and radiculopathy (aOR, 4.8). Three decision tree models showed that symptom type and radiographic diagnosis had the highest variable importance. CONCLUSIONS: Appropriate use criteria for cervical fusion in the setting of cervical degenerative disorders were developed. Symptom type was most strongly correlated with final rating. Myelopathy or radiculopathy were most strongly associated with an "Appropriate" rating, while axial pain without stenosis was most associated with "Rarely Appropriate."

Diagnosis of unstable cervical spine injuries: laboratory support for the use of axial traction to diagnose cervical spine instability.

BACKGROUND: The ability to detect damage to the intervertebral structures is critical in the management of patients after blunt trauma. A practical and inexpensive method to identify severe structural damage not clearly seen on computed tomography would be of benefit. The objective of this study was to assess whether ligamentous injury in the subaxial cervical spine can be reliably detected by analysis of lateral radiographs taken with and without axial traction. METHODS: Twelve fresh, whole, postrigor-mortis cadavers were used for this study. Lateral cervical spine radiographs were obtained during the application of 0 N, 89 N, and 178 N of axial traction applied to the head. Progressive incremental sectioning of posterior structures was then performed at C4-C5 with traction imaging repeated after each intervention. Intervertebral distraction was analyzed using computer-assisted software. RESULTS: Almost imperceptible intervertebral separation was found when traction was applied to intact spines. In the subaxial cervical spine, the average posterior disc height consistently increased under traction in severely injured spines. The average disc height increase was 14% of the C4 upper endplate width, compared with an average of 2% in the noninjured spines. A change of more than 5% in posterior disc height under traction was above the 95% confidence interval for intact spines, with sensitivity of 83% and specificity of 80%. Applied force of 89 N (20 lb) was sufficient to demonstrate injury. The combination of assessing alignment and distraction under traction increased both the sensitivity and specificity to nearly 100%. CONCLUSION: This study supports further clinical investigations to determine whether low-level axial traction may be a useful adjunct for detecting unstable subaxial cervical spine injuries in an acute setting.

Extrication collars can result in abnormal separation between vertebrae in the presence of a dissociative injury.

BACKGROUND: Cervical collars are applied to millions of trauma victims with the intent of protecting against secondary spine injuries. Adverse clinical outcomes during the management of trauma patients led to the hypothesis that extrication collars may be harmful in some cases. The literature provides indirect support for this observation. The purpose of this study was to directly evaluate cervical biomechanics after application of a cervical collar in the presence of severe neck injury. METHODS: Cranial-caudal displacements in the upper cervical spine were measured in cadavers from images taken before and after application of collars following creation of an unstable upper cervical spine injury. RESULTS: In the presence of severe injury, collar application resulted in 7.3 mm +/- 4.0 mm of separation between C1 and C2 in a cadaver model. In general, collars had the effect of pushing the head away from the shoulders. CONCLUSIONS: This study was consistent with previous evidence that extrication collars can result in abnormal distraction within the upper cervical spine in the presence of a severe injury. These observations support the need to prioritize additional research to better understand the risks and benefits of cervical stabilization methods and to determine whether improved stabilization methods can help to avoid potentially harmful displacements between vertebrae.