Formal Radiologist Interpretations of Intraoperative Spine Radiographs Have Low Clinical Value.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To evaluate the clinical relevance, usefulness, and financial implications of intraoperative radiograph interpretation by radiologists in spine surgery. SUMMARY OF BACKGROUND DATA: Due to rising health care costs, spine surgery is under scrutiny to maximize value-based care. Formal radiographic analysis remains a potential source of unnecessary health care costs, especially for intraoperative radiographs. MATERIALS AND METHODS: A retrospective cohort analysis was performed on all adult elective spine surgeries at a single institution between July 2020 and July 2021. Demographic and radiographic data were collected, including intraoperative localization and post-instrumentation radiographs. Financial data were obtained through the institution's price estimator. Radiographic characteristics included time from radiographic imaging to completion of radiologist interpretation report, completion of radiologist interpretation report before the conclusion of surgical procedure, clinical relevance, and clinical usefulness. Reports were considered clinically relevant if the spinal level of the procedure was described and clinically useful if completed before the conclusion of the procedure and deemed clinically relevant. RESULTS: Four hundred eighty-one intraoperative localization and post-instrumentation radiographs from 360 patients revealed a median delay of 128 minutes between imaging and completion of the interpretive report. Only 38.9% of reports were completed before the conclusion of surgery. There were 79.4% deemed clinically relevant and only 33.5% were clinically useful. Localization reports were completed more frequently before the conclusion of surgery (67.2% vs. 34.4%) but with lower clinical relevance (90.1% vs. 98.5%) and clinical usefulness (60.3% vs. 33.6%) than post-instrumentation reports. Each patient was charged $32 to $34 for the interpretation fee, cumulating a minimum total cost of $15,392. CONCLUSIONS: Formal radiographic interpretation of intraoperative spine radiographs was of low clinical utility for spine surgeons. Institutions should consider optimizing radiology workflows to improve timeliness and clinical relevance or evaluate the necessity of reflexive consultation to radiology for intraoperative imaging interpretation to ensure that value-based care is maximized during spine surgeries. LEVEL OF EVIDENCE: 3.

MicroRNA-29a: a novel target for non-operative management of symptomatic lumbar spinal stenosis.

PURPOSE: Lumbar spinal stenosis (LSS) is the most common reason for spinal surgery in patients over the age of 65, and there are few effective non-surgical treatments. Therefore, the development of novel treatment or preventative modalities to decrease overall cost and morbidity associated with LSS is an urgent matter. The cause of LSS is multifactorial; however, a significant contributor is ligamentum flavum hypertrophy (LFH) which causes mechanical compression of the cauda equina or nerve roots. We assessed the role of a novel target, microRNA-29a (miR-29a), in LFH and investigated the potential for using miR-29a as a therapeutic means to combat LSS. METHODS: Ligamentum flavum (LF) tissue was collected from patients undergoing decompressive surgery for LSS and assessed for levels of miR-29a and pro-fibrotic protein expression. LF cell cultures were then transfected with either miR-29a over-expressor (agonist) or inhibitor (antagonist). The effects of over-expression and under-expression of miR-29a on expression of pro-fibrotic proteins was assessed. RESULTS: We demonstrated that LF at stenotic levels had a loss of miR-29a expression. This was associated with greater LF tissue thickness and higher mRNA levels of collagen I and III. We also demonstrated that miR29-a plays a direct role in the regulation of collagen gene expression in ligamentum flavum. Specifically, agents that increase miR-29a may attenuate LFH, while those that decrease miR-29a promote fibrosis and LFH. CONCLUSION: This study demonstrates that miR-29a may potentially be used to treat LFH and provides groundwork to initiate the development of a therapeutic product for LSS.

Development and validation of a large animal ovine model for implant-associated spine infection using biofilm based inocula.

Postoperative implant-associated spine infection remains poorly understood. Currently there is no large animal model using biofilm as initial inocula to study this challenging clinical entity. The purpose of the present study was to develop a sheep model for implant-associated spine infection using clinically relevant biofilm inocula and to assess the in vivo utility of methylene blue (MB) for visualizing infected tissues and guiding debridement. This 28-day study used five adult female Rambouillet sheep, each with two non-contiguous surgical sites- in the lumbar and thoracic regions- comprising randomized positive and negative infection control sites. A standard mini-open approach to the spine was performed to place sterile pedicle screws and Staphylococcus aureus biofilm-covered (positive control), or sterile (negative control) spinal fusion rods. Surgical site bioburden was quantified at the terminal procedure. Negative and positive control sites were stained with MB and staining intensity quantified from photographs. Specimens were analyzed with x-ray, micro-CT and histologically. Inoculation rods contained ∼10.44 log10 colony forming units per rod (CFU/rod). Biofilm inocula persisted on positive-control rod explants with ∼6.16 log10 CFU/rod. There was ∼6.35 log10 CFU/g of tissue in the positive controls versus no identifiable bioburden in the negative controls. Positive controls displayed hallmarks of deep spine infection and osteomyelitis, with robust local tissue response, bone resorption, and demineralization. MB staining was more intense in infected, positive control sites. This work presents an animal-efficient sheep model displaying clinically relevant implant-associated deep spine infection.

Examining the safety profile of a standard dose tranexamic acid regimen in spine surgery.

OBJECTIVE: Perioperative blood loss during spinal surgery is associated with complications and in-hospital mortality. Weight-based administration of tranexamic acid (TXA) has the potential to reduce blood loss and related complications in spinal surgery; however, evidence for standardized dosing is lacking. The purpose of this study was to evaluate the impact of a standardized preoperative 2 g bolus TXA dosing regimen on perioperative transfusion, blood loss, thromboembolic events, and postoperative outcomes in spine surgery patients. METHODS: An institutional review board approved this retrospective review of prospectively enrolled adult spine patients (> 18 years of age). Patients were included who underwent elective and emergency spine surgery between September 2018 and July 2021. Patients who received a standardized 2 g dose of TXA were compared to patients who did not receive TXA. The primary outcome measure was perioperative transfusion. Secondary outcomes included estimated blood loss and thromboembolic or other perioperative complications. Descriptive statistics were calculated, and continuous variables were analyzed with the two-tailed independent t-test, while categorical variables were analyzed with the Fisher's exact test or chi-square test. Stepwise multivariate regression analysis was performed to examine independent risk factors for perioperative outcomes. RESULTS: TXA was administered to 353 of 453 (78%) patients, and there were no demographic differences between groups. Although the TXA group had more operative levels and a longer operative time, the transfusion rate was not different between the TXA and no-TXA groups (7.4% vs 8%, p = 0.83). Stepwise multivariate regression found that the number of operative levels was an independent predictor of perioperative transfusion and that both operative levels and operative time were correlated with estimated blood loss. TXA was not identified as an independent predictor of any postoperative complication. CONCLUSIONS: A standardized preoperative 2 g bolus TXA dosing regimen was associated with an excellent safety profile, and despite increased case complexity in terms of number of operative levels and operative time, patients treated with TXA did not require more blood transfusions than patients not treated with TXA.

Patterns in Follow-Up Imaging Usage for Pediatric Patients with Whiplash-Associated Disorder.

BACKGROUND: A clinical concern exists that pediatric patients with whiplash-associated disorder (WAD) might have missed structural injuries or, alternatively, subsequently develop structural injuries over time, despite initially negative imaging findings. The primary objective of this study is to assess follow-up imaging usage for pediatric patients presenting with WAD. METHODS: A retrospective review of 444 pediatric patients presenting to a level 1 pediatric trauma hospital from January 1, 2010 to December 31, 2019 was performed. Imaging was reviewed at the initial encounter and the 3- and 6-month follow-up appointments. RESULTS: At the initial evaluation, children aged <6 years were more likely to receive radiographs (P = 0.007) and magnetic resonance imaging (P = 0.048) than were children aged 6-11 and 12-18 years. At the 3- and 6-month follow-up appointments, persistent neck pain was rare, representing <15% of patients at either time. Regardless of pain persistence, 80.2% of patients seen at the 3-month follow-up and 100% of patients at the 6-month follow-up underwent additional imaging studies. At the 3-month follow-up, children with persistent neck pain were more likely to undergo magnetic resonance imaging than were patients without persistent pain (P < 0.001). Also, patients with persistent neck pain were also more likely to not undergo any imaging evaluation (P = 0.002). Follow-up imaging studies did not reveal new structural injuries at either time point. CONCLUSIONS: Follow-up imaging for pediatric patients with low-grade WAD did not identify new structural pathology-in patients with or without persistent neck pain.

Management of High-Energy Tibial Pilon Fractures.

➤ Pilon fractures in the younger patient population are frequently high-energy, intra-articular injuries and are associated with devastating, long-term impacts on patient-reported outcomes and health-related quality of life, as well as high rates of persistent disability.➤ Judicious management of associated soft-tissue injury, including open fractures, is essential to minimizing complications. Optimizing medical comorbidities and negative social behaviors (e.g., smoking) should be addressed perioperatively.➤ Delayed internal fixation with interval temporizing external fixation represents the preferred technique for managing most high-energy pilon fractures presenting with characteristically substantial soft-tissue trauma. In some cases, surgeons elect to utilize circular fixation for these scenarios.➤ Although there have been treatment advances, the results have been generally poor, with high rates of posttraumatic arthritis, despite expert care.➤ Primary arthrodesis may be indicated in cases with severe articular cartilage injury that, in the opinion of the treating surgeon, is likely unsalvageable at the time of the index management.➤ The addition of intrawound vancomycin powder at the time of definitive fixation represents a low-cost prophylactic measure that appears to be effective in reducing gram-positive deep surgical site infections.

Spine Fractures of Patients with Ankylosing Spondylitis and Diffuse Idiopathic Skeletal Hyperostosis: Fracture Severity and Injury-Related Mortality at a Level I Trauma Center.

STUDY DESIGN: Retrospective review of prospectively collected cohort. PURPOSE: To identify differences in treatment and mortality of spine fractures in patients with ankylosing conditions of the spine. OVERVIEW OF LITERATURE: Ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) are the two most common etiologies of ankylosing spinal disorder (ASD). However, studies on the treatment and outcomes of spine fractures in AS and DISH patients remain few. METHODS: Patients presenting with a spine fracture were diagnosed with AS or DISH at a single tertiary care center between 2010 and 2019. We excluded those who lacked cross-sectional imaging or fractures occurring at spinal segments affected by ankylosis, as well as polytraumatized patients. Patient demographics, injury mechanism, fracture level, neurologic status, treatment, and 1-year mortality were recorded. Computed tomography imaging was reviewed by two independent readers and graded according to the indicated AO Spine Injury Classification System. Differences in fracture severity, treatment method, and mortality were examined using Student t -tests, chi-square tests, and two-proportion Z-tests with significance set to p <0.05. RESULTS: We identified 167 patients with spine fracture diagnosed with AS or DISH. Patients with AS had more severe fractures and more commonly had surgery than patients with DISH (p <0.001). Despite these differences, 1-year mortality did not significantly differ between AS and DISH patients (p =0.14). CONCLUSIONS: Although patients with AS suffered more severe fractures compared to DISH and more frequently underwent surgery for these injuries, outcomes and 1-year mortality did not differ significantly between the two groups. For patients with ASDs and fractures, outcomes appear similar regardless of treatment modality. Consequently, there may be an opportunity for critical reappraisal of operative indications in ASD and a larger role for nonoperative management in these challenging patients.

Pre-Operative Bariatric Surgery Imparts An Increased Risk of Infection, Re-Admission and Operative Intervention Following Elective Instrumented Lumbar Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To evaluate the impact of bariatric surgery on patient outcomes following elective instrumented lumbar fusion. METHODS: A retrospective review of a prospectively collected database was performed. Patients who underwent a bariatric procedure prior to an elective instrumented lumbar fusion were evaluated. Lumbar procedures were performed at a large academic medical center from 1/1/2012 to 1/1/2018. The primary outcome was surgical site infection (SSI) requiring surgical debridement. Secondary outcomes were prolonged wound drainage requiring treatment, implant failure requiring revision, revision secondary to adjacent segment disease (ASD), and chronic pain states. A randomly selected, surgeon and comorbidity-matched group of 59 patients that underwent an elective lumbar fusion during that period was used as a control. Statistical analysis was performed using Student's two-way t-tests for continuous data, with significance defined as P < .05. RESULTS: Twenty-five patients were identified who underwent bariatric surgery prior to elective lumbar fusion. Mean follow-up was 2.4 ± 1.9 years in the bariatric group vs. 1.5 ± 1.3 years in the control group. Patients with a history of bariatric surgery had an increased incidence of SSI that required operative debridement, revision surgery due to ASD, and a higher incidence of chronic pain. Prolonged wound drainage and implant failure were equivalent between groups. CONCLUSION: In the present study, bariatric surgery prior to elective instrumented lumbar fusion was associated increased risk of surgical site infection, adjacent segment disease and chronic pain when compared to non-bariatric patients.

Postoperative radial nerve palsy in humeral shaft nonunion reconstruction: Can the lateral paratricipital approach prevent this common complication?

BACKGROUND: Postoperative radial nerve palsy (RNP) is a well-known complication of nonunion reconstruction of the humerus. The purpose of the current study is to determine if the surgical approach for nonunion reconstruction of the humerus influences the rate of postoperative radial nerve palsy. METHODS: A retrospective case-control study of all humeral shaft and extraarticular distal humerus nonunion reconstructions performed between January 1, 2004, and August 31, 2021, was conducted. Patients included were over 18 years of age, had a non-pathologic humerus fracture nonunion and had intact radial nerve function prior to nonunion reconstruction. Exclusion criteria consisted of nonunions involving the proximal humerus, intraarticular fractures, and reconstructive treatment procedures with either intramedullary nail or external fixation methods. Perioperative variables were recorded and analyzed in regard to the development of postoperative RNP. A subgroup analysis was performed to assess the interaction of significant variables on the development of postoperative RNP. RESULTS: The overall rate of postoperative RNP in this series was 6/53 (11%). However, no cases of postoperative radial nerve palsy were observed in patients who underwent nonunion reconstruction with a lateral paratricipital approach. A new RNP was seen in 4/9 (44%) of those patients who underwent a triceps splitting approach, which was significantly higher than those utilizing either an anterolateral approach (2/28, 7%) or a lateral paratricipital approach (0/16, 0%, p = 0.007). DISCUSSION AND CONCLUSION: Our data suggests that the lateral paratricipital exposure decreases the risk of radial nerve injury with nonunion reconstruction of the humerus. The lateral paratricipital exposure offers the benefit of radial nerve exploration, decompression, neurolysis and protection prior to fracture manipulation and instrumentation. This study shows conventional approaches may predispose patients to a high rate of postoperative RNP, similar to that in the literature.

Percutaneous lumbar annular puncture: A rat model to study intervertebral disc degeneration and pain-related behavior.

Background: Previous animal models of intervertebral disc degeneration (IDD) rely on open surgical approaches, which confound the degenerative response and pain behaviors due to injury to surrounding tissues during the surgical approach. To overcome these challenges, we developed a minimally invasive percutaneous puncture procedure to induce IDD in a rat model. Methods: Ten Fischer 344 male rats underwent percutaneous annular puncture of lumbar intervertebral discs (IVDs) at L2-3, L3-4, and L4-5. Ten unpunctured rats were used as controls. Magnetic resonance imagings (MRIs), serum biomarkers, and behavioral tests were performed at baseline and 6, 12, and 18 weeks post puncture. Rats were sacrificed at 18 weeks and disc histology, immunohistochemistry, and glycosaminoglycan (GAG) assays were performed. Results: Punctured IVDs exhibited significant reductions in MRI signal intensity and disc volume. Disc histology, immunohistochemistry, and GAG assay results were consistent with features of IDD. IVD-punctured rats demonstrated significant changes in pain-related behaviors, including total distance moved, twitching frequency, and rearing duration. Conclusions: This is the first reported study of the successful establishment of a reproducible rodent model of a percutaneous lumbar annular puncture resulting in discogenic pain. This model will be useful to test therapeutics and elucidate the basic mechanisms of IDD and discogenic pain.

The presence of a draining sinus is associated with failure of re-implantation during two-stage exchange arthroplasty.

Background: Reinfection rates after two-stage exchange arthroplasty for prosthetic joint infection (PJI) have been reported as high as 33 % in the literature. Understanding risk factors for treatment failure will help to preoperatively counsel patients on the likelihood of successful treatment and possibly influence the surgeon's treatment algorithm. This study aimed to delineate whether the presence of a draining sinus tract is associated with risk of failure of two-stage exchange arthroplasty. Methods: We performed a single institution, multi-center retrospective chart review of outcomes of patients treated for PJI with two-stage exchange arthroplasty between June 2006 and May 2016. For patients treated prior to 2011, PJI was defined based on the preoperative work-up and intraoperative findings as determined by the attending surgeon. After 2011, PJI was defined using MSIS consensus criteria. All patients had a minimum of follow-up of 2 years or treatment failure prior to 2 years. Treatment failure was defined as reinfection or failure to complete two-stage exchange secondary to persistent infection or other host factors. Operative reports and clinical notes were reviewed to assess for presence of a draining sinus tract. Results: 240 patients were treated for PJI with intended two-stage exchange arthroplasty. The overall rate of treatment failure was 29.6 % ( 71 / 240 ), while the overall rate of reinfection was 13.3 % ( 32 / 240 ). A total of 39 patients did not complete second stage revision; final treatment for these patients was amputation, fusion, or chronic antibiotic suppression. A total of 52 of 240 patients (21.7 %) had a draining sinus tract at presentation. Patients with a sinus tract were significantly less likely to be replanted compared to those without a sinus tract at presentation (13.3 % vs. 26.9 %, p = 0.02 ). However, when accounting for all mechanisms of treatment failure, including reinfection following replantation, there was no statistically significant difference detected between the sinus and no-sinus groups (27.7 % vs. 36.5 %, p = 0.22 ). Discussion: A draining sinus tract represents a chronic, deep infectious process with ultimate compromise of overlying soft tissues. Thus we hypothesized it would be associated with failure in a two-stage exchange arthroplasty. These data demonstrate that patients with a draining sinus are significantly less likely to undergo re-implantation. This provides evidence to the paucity of data surrounding draining sinuses and two-stage PJI treatment.

Male sex, Gustillo-Anderson type III open fracture and definitive external fixation are risk factors for a return to the or following the surgical management of geriatric low energy open ankle fractures.

INTRODUCTION: Open ankle fractures in geriatric (age > 60 years) patients are a source of significant morbidity and mortality. Surgical management includes plate and screw fixation (ORIF), retrograde hindfoot nail (HFN), definitive external fixation (ex-fix) and below knee amputation. However, each modality poses unique challenges for this population. We sought to identify predictors of unplanned OR and short-term mortality after geriatric open ankle fractures managed by our service. MATERIALS AND METHODS: In an IRB-approved protocol, we evaluated patients over 60 years of age managed for a low energy open ankle/distal tibia pilon fracture by trauma fellowship-trained surgeons from a single academic department that covers two level I trauma centers. Our primary outcome was an unplanned return to the OR. Secondary outcomes were a 90-day "event", defined as an all-cause hospital readmission or mortality, and 1-year mortality. Differences with a p-value < 0.1 measured on univariate analysis were evaluated using a multivariable logistic regression to identify independent outcome predictors. RESULTS: A total of 113 (60 ORIF, 36 HFN, 11 ex-fix, 6 amputations) were performed. Cohort mean age was 75.2 ± 9.8 years, and 31 patients (27.4%) were male. Mean age-adjusted charlson comorbidity index was 5.5 ± 2.0. Significant independent predictors of an unplanned return to the OR were male sex (OR 4.4, 95% CI 1.3 to 15.4), Gustilo Type III open fracture (OR 4.9, 95% CI 1.5 to 17.5) and ex-fix (OR 15.6, 95% CI 2.7 to 126.3). Independent predictors of a 90-day "event" were walker/minimal ambulation (OR 3.5, 95% CI 1.3 to 10.4), surgical site infection (OR 4.8, 95% CI 1.8 to 13.8) and reduced BMI (OR 0.9, 95% CI 0.9 - 0.99), while independent predictors of 1-year mortality were age (OR 1.1, 95% CI 1.003 to 1.2), ACCI (OR 1.4, 95% CI 1.02 to 2.0) and walker/minimal ambulator (OR 7.5, 95% CI 1.7 to 53) CONCLUSIONS: Host factors, particularly pre-operative mobility, were most predictive of 90-day event and 1-year mortality. Only definitive external fixation was found to influence patient morbidity as a significant predictor of unplanned OR. However, no surgical modality had any influence on short-term readmission or survival.

Residual Motion and Graft Type Do Not Influence Patient-reported Outcomes Following One- or Two-level Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Prospective cohort. OBJECTIVE: The aim of this study was to determine the effect of graft type on residual motion and the relationship among residual motion, smoking, and patient-reported outcome (PRO) scores following anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA: Although most patients develop solid fusion based on static imaging following ACDF, dynamic imaging has revealed that many patients continue to have residual motion at the arthrodesis. METHODS: Forty-eight participants performed dynamic neck flexion/extension and axial rotation within a biplane radiography system 1 year following ACDF (21 one-level, 27 two-level). PRO scores included the Short Form-36, Neck Disability Index, and Cervical Spine Outcomes Questionnaire. An automated model-based tracking process matched subject-specific bone models to the biplane radiographs with sub-millimeter accuracy. Residual motion was measured across the entire arthrodesis site for both one- and two-level fusions in patients who received either allograft or autograft. Patients were divided into "pseudarthrosis" (>3° of flexion/extension residual motion) and "solid fusion" groups. Residual motion and PROs were compared between groups using Student t tests. RESULTS: Patients who received allograft showed more total flexion/extension residual motion (4.1° vs. 2.8°, P = 0.12), although this failed to reach significance. No differences were noted in PROs based on graft type (all P > 0.08) or the presence of pseudarthrosis (all P > 0.13). No differences were noted in residual motion between smokers and nonsmokers (all P > 0.15); however, smokers who received allograft reported worse outcomes than nonsmokers who received allograft and smokers who received autograft. CONCLUSION: Allograft may result in slightly more residual motion at the arthrodesis site 1 year after ACDF. However, there is minimal evidence that PROs are adversely affected by slightly increased residual motion, suggesting that the current definition of pseudarthrosis correlates poorly with clinically significant findings. Additionally, autograft appears to result in superior outcomes in patients who smoke.Level of Evidence: 2.

ISSLS prize in basic science 2021: a novel inducible system to regulate transgene expression of TIMP1.

PURPOSE: Inflammatory and oxidative stress upregulates matrix metalloproteinase (MMP) activity, leading to intervertebral disc degeneration (IDD). Gene therapy using human tissue inhibitor of metalloproteinase 1 (hTIMP1) has effectively treated IDD in animal models. However, persistent unregulated transgene expression may have negative side effects. We developed a recombinant adeno-associated viral (AAV) gene vector, AAV-NFκB-hTIMP1, that only expresses the hTIMP1 transgene under conditions of stress. METHODS: Rabbit disc cells were transfected or transduced with AAV-CMV-hTIMP1, which constitutively expresses hTIMP1, or AAV-NFκB-hTIMP1. Disc cells were selectively treated with IL-1ß. NFκB activation was verified by nuclear translocation. hTIMP1 mRNA and protein expression were measured by RT-PCR and ELISA, respectively. MMP activity was measured by following cleavage of a fluorogenic substrate. RESULTS: IL-1ß stimulation activated NFκB demonstrating that IL-1ß was a surrogate for inflammatory stress. Stimulating AAV-NFκB-hTIMP1 cells with IL-1ß increased hTIMP1 expression compared to unstimulated cells. AAV-CMV-hTIMP1 cells demonstrated high levels of hTIMP1 expression regardless of IL-1ß stimulation. hTIMP1 expression was comparable between IL-1ß stimulated AAV-NFκB-hTIMP1 cells and AAV-CMV-hTIMP1 cells. MMP activity was decreased in AAV-NFκB-hTIMP1 cells compared to baseline levels or cells exposed to IL-1ß. CONCLUSION: AAV-NFκB-hTIMP1 is a novel inducible transgene delivery system. NFκB regulatory elements ensure that hTIMP1 expression occurs only with inflammation, which is central to IDD development. Unlike previous inducible systems, the AAV-NFκB-hTIMP1 construct is dependent on endogenous factors, which minimizes potential side effects caused by constitutive transgene overexpression. It also prevents the unnecessary production of transgene products in cells that do not require therapy.

Assessing the biofidelity of in vitro biomechanical testing of the human cervical spine.

In vitro biomechanical studies of the osteoligamentous spine are widely used to characterize normal biomechanics, identify injury mechanisms, and assess the effects of degeneration and surgical instrumentation on spine mechanics. The objective of this study was to determine how well four standards in vitro loading paradigms replicate in vivo kinematics with regards to the instantaneous center of rotation and arthrokinematics in relation to disc deformation. In vivo data were previously collected from 20 asymptomatic participants (45.5 ± 5.8 years) who performed full range of motion neck flexion-extension (FE) within a biplane x-ray system. Intervertebral kinematics were determined with sub-millimeter precision using a validated model-based tracking process. Ten cadaveric spines (51.8 ± 7.3 years) were tested in FE within a robotic testing system. Each specimen was tested under four loading conditions: pure moment, axial loading, follower loading, and combined loading. The in vivo and in vitro bone motion data were directly compared. The average in vitro instant center of rotation was significantly more anterior in all four loading paradigms for all levels. In general, the anterior and posterior disc heights were larger in the in vitro models than in vivo. However, after adjusting for gender, the observed differences in disc height were not statistically significant. This data suggests that in vitro biomechanical testing alone may fail to replicate in vivo conditions, with significant implications for novel motion preservation devices such as cervical disc arthroplasty implants.

Severe pulmonary injury leading to death during thoracic rod removal: a case report.

PURPOSE: Removal of hardware procedures following posterior spinal fusion is most commonly performed for hardware irritation without overt infection. It is imperative that surgeons realize that serious complications may arise from this procedure. The purpose of this report is to report a case of a pneumothorax that developed in a thoracolumbar removal of hardware case that resulted in a patient death. METHODS: Retrospective review of a patient's medical record and imaging. RESULTS: A 74-year-old patient with a history of T4-10 anterior discectomy and fusion with rib autograft and T4-L2 posterior fusion underwent a removal of hardware procedure for delayed surgical site infection. During the procedure, the tip of the bolt cutter jaw broke and entered the pulmonary cavity leading to a pneumothorax. The patient developed pneumonia 1 month postoperatively and passed away. CONCLUSIONS: This case report highlights one of the rare but potential complications of spinal removal of hardware surgery. It is essential that surgeons are aware of the possibility of pulmonary complications during thoracolumbar removal of hardware cases so that they may fully counsel their patients on the potential risks.

Use of Fondaparinux Following Elective Lumbar Spine Surgery Is Associated With a Reduction in Symptomatic Venous Thromboembolism.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To assess the impact of fondaparinux on venous thromboembolism (VTE) following elective lumbar spine surgery in high-risk patients. METHODS: Matched patient cohorts who did or did not receive inpatient fondaparinux starting postoperative day 2 following elective lumbar spine surgery were compared. All patients received 1 month of acetyl salicylic acid 325 mg following discharge. The primary outcome was a symptomatic DVT (deep vein thrombosis) or PE (pulmonary embolus) within 30 days of surgery. Secondary outcomes included prolonged wound drainage, epidural hematoma, and transfusion. RESULTS: A significantly higher number of DVTs were diagnosed in the group that did not receive inpatient VTE prophylaxis (3/102, 2.9%) compared with the fondaparinux group (0/275, 0%, P = .02). Increased wound drainage was seen in 18.5% of patients administered fondaparinux, compared with 25.5% of untreated patients (P = .15). Deep infections were equivalent (2.2% with fondaparinux vs 4.9% control, P = .18). No epidural hematomas were noted, and the number of transfusions after postoperative day 2 and 90-day return to operating room rates were equivalent. CONCLUSIONS: Patients receiving fondaparinux had lower rates of symptomatic DVT and PE and a favorable complication profile when compared with matched controls. The retrospective nature of this work limits the safety and efficacy claims that can be made about the use of fondaparinux to prevent VTE in elective lumbar spine surgery patients. Importantly, this work highlights the potential safety of this regimen, permitting future high-quality trials.

Undisclosed Conflict of Interest Is Prevalent in Spine Literature.

STUDY DESIGN: Cohort study. OBJECTIVE: The aim of this study was to determine the rate of accurate conflict of interest (COI) disclosure within three prominent subspecialty Spine journals during a 4-year period. SUMMARY OF BACKGROUND DATA: Industry-physician relationships are crucial for technological advancement in spine surgery but serve as a source of bias in biomedical research. The Open Payments Database (OPD) was established after 2010 to increase financial transparency. METHODS: All research articles published from 2014 to 2017 in Spine, The Spine Journal (TSJ), and the Journal of Neurosurgery: Spine (JNS) were reviewed in this study. In these articles, all author's COI statements were recorded. The OPD was queried for all author entries within the disclose period of the journal. Discrepancies between the author's self-reported COIs and the documented COIs from OPD were recorded. RESULTS: A total of 6816 articles meeting inclusion criteria between 2014 and 2017 in Spine, TSJ, and JNS with 39,869 contributing authors. Overall, 15.8% of all authors were found to have an OPD financial relationship. Of 2633 authors in Spine with financial disclosures, 77.1% had accurate financial disclosures; 42.5% and 41.0% of authors with financial relationships in the OPD had accurate financial disclosures in TSJ and JNS, respectively. The total value of undisclosed conflicts of interest between 2014 and 2017 was $421 million with $1.48 billion in accurate disclosures. Of undisclosed payments, 68.7% were <$1000 and only 7.2% were >$10,000. Undisclosed payments included $180 million in research funding and $188 million in royalties. CONCLUSION: This study demonstrates that undisclosed COI is highly prevalent for authors in major Spine journals. This study indicates that there remains a need to standardize definitions and financial thresholds for significant COI as well as to shift the reporting burden for COI to journals who actively review potential COIs instead of relying on self-reporting. LEVEL OF EVIDENCE: 3.