Broad-spectrum antibiotic prophylaxis in tumor and infected orthopedic surgery-the prospective-randomized, microbiologist-blinded, stratified, superiority trials: BAPTIST Trials

BACKGROUND

The perioperative antibiotic prophylaxis with 1st or 2nd generation cephalosporins is evidence-based in orthopedic surgery. There are, however, situations with a high risk of prophylaxis-resistant surgical site infections (SSI).

METHODS

We perform a superiority randomized controlled trial with a 10% margin and a power of 90% in favor of the broad-spectrum prophylaxis. We will randomize orthopedic interventions with a high risk for SSI due to selection of resistant pathogens (open fractures, surgery under therapeutic antibiotics, orthopedic tumor surgery, spine surgery with American Society of Anesthesiologists (ASA) score ≥ 3 points) in a prospective-alternating scheme (1:1, standard prophylaxis with cefuroxime versus a broad-spectrum prophylaxis of a combined single-shot of vancomycin 1 g and gentamicin 5 mg/kg parenterally). The primary outcome is "remission" at 6 weeks for most orthopedic surgeries or at 1 year for surgeries with implant. Secondary outcomes are the risk for prophylaxis-resistant SSI pathogens, revision surgery for any reason, change of antibiotic therapy during the treatment of infection, adverse events, and the postoperative healthcare-associated infections other than SSI within 6 weeks (e.g., urine infections or pneumonia). With event-free surgeries to 95% in the broad-spectrum versus 85% in the standard prophylaxis arm, we need 2 × 207 orthopedic surgeries.

DISCUSSION

In selected patients with a high risk for infections due to selection of prophylaxis-resistant SSI, a broad-spectrum combination with vancomycin and gentamycin might prevent SSIs (and other postoperative infections) better than the prophylaxis with cefuroxime.

TRIAL REGISTRATION

ClinicalTrial.gov NCT05502380. Registered on 12 August 2022. Protocol version: 2 (3 June 2022).

Perioperative Urinary Catheter Use and Association to (Gram-Negative) Surgical Site Infection after Spine Surgery

This study evaluates potential associations between the perioperative urinary catheter (UC) carriage and (Gram-negative) surgical site infections (SSIs) after spine surgery. It is a retrospective, single-center, case-control study stratifying group comparisons, case-mix adjustments using multivariate logistic regression analyses. Around half of the patients (2734/5485 surgeries) carried a UC for 1 day (median duration) (interquartile range, 1-1 days). Patients with perioperative UC carriage were compared to those without regarding SSI, in general, and Gram-negative, exclusively. The SSI rate was 1.2% (67/5485), yielding 67 revision surgeries. Gram-negative pathogens caused 16 SSIs. Seven Gram-negative episodes revealed the same pathogen concomitantly in the urine and the spine. In the multivariate analysis, the UC carriage duration was associated with SSI (OR 1.1, 95% confidence interval 1.1-1.1), albeit less than classical risk factors like diabetes (OR 2.2, 95%CI 1.1-4.2), smoking (OR 2.4, 95%CI 1.4-4.3), or higher ASA-Scores (OR 2.3, 95%CI 1.4-3.6). In the second multivariate analysis targeting Gram-negative SSIs, the female sex (OR 3.8, 95%CI 1.4-10.6) and a UC carriage > 1 day (OR 5.5, 95%CI 1.5-20.3) were associated with Gram-negative SSIs. Gram-negative SSIs after spine surgery seem associated with perioperative UC carriage, especially in women. Other SSI risk factors are diabetes, smoking, and higher ASA scores.

Increased cranio-caudal spinal cord oscillations are the cardinal pathophysiological change in degenerative cervical myelopathy

Introduction

Degenerative cervical myelopathy (DCM) is the most common cause of non-traumatic incomplete spinal cord injury, but its pathophysiology is poorly understood. As spinal cord compression observed in standard MRI often fails to explain a patient's status, new diagnostic techniques to assess DCM are one of the research priorities. Minor cardiac-related cranio-caudal oscillations of the cervical spinal cord are observed by phase-contrast MRI (PC-MRI) in healthy controls (HCs), while they become pathologically increased in patients suffering from degenerative cervical myelopathy. Whether transversal oscillations (i.e., anterior-posterior and right-left) also change in DCM patients is not known.

Methods

We assessed spinal cord motion simultaneously in all three spatial directions (i.e., cranio-caudal, anterior-posterior, and right-left) using sagittal PC-MRI and compared physiological oscillations in 18 HCs to pathological changes in 72 DCM patients with spinal canal stenosis. The parameter of interest was the amplitude of the velocity signal (i.e., maximum positive to maximum negative peak) during the cardiac cycle.

Results

Most patients suffered from mild DCM (mJOA score 16 (14-18) points), and the majority (68.1%) presented with multisegmental stenosis. The spinal canal was considerably constricted in DCM patients in all segments compared to HCs. Under physiological conditions in HCs, the cervical spinal cord oscillates in the cranio-caudal and anterior-posterior directions, while right-left motion was marginal [e.g., segment C5 amplitudes: cranio-caudal: 0.40 (0.27-0.48) cm/s; anterior-posterior: 0.18 (0.16-0.29) cm/s; right-left: 0.10 (0.08-0.13) cm/s]. Compared to HCs, DCM patients presented with considerably increased cranio-caudal oscillations due to the cardinal pathophysiologic change in non-stenotic [e.g., segment C5 amplitudes: 0.79 (0.49-1.32) cm/s] and stenotic segments [.g., segment C5 amplitudes: 0.99 (0.69-1.42) cm/s]). In contrast, right-left [e.g., segment C5 amplitudes: non-stenotic segment: 0.20 (0.13-0.32) cm/s; stenotic segment: 0.11 (0.09-0.18) cm/s] and anterior-posterior oscillations [e.g., segment C5 amplitudes: non-stenotic segment: 0.26 (0.15-0.45) cm/s; stenotic segment: 0.11 (0.09-0.18) cm/s] remained on low magnitudes comparable to HCs.

Conclusion

Increased cranio-caudal oscillations of the cervical cord are the cardinal pathophysiologic change and can be quantified using PC-MRI in DCM patients. This study addresses spinal cord oscillations as a relevant biomarker reflecting dynamic mechanical cord stress in DCM patients, potentially contributing to a loss of function.

A Simple Preoperative Score Predicting Failure Following Decompression Surgery for Degenerative Lumbar Spinal Stenosis

BACKGROUND CONTEXT

Proper patient selection is crucial for the outcome of surgically treated degenerative lumbar spinal stenosis (DLSS). Nevertheless, there is still not a clear consensus regarding the optimal treatment option for patients with DLSS.

PURPOSE

To investigate the treatment failure rate and introduce a simple, preoperative score to aid surgical decision-making.

STUDY DESIGN/SETTING

Retrospective observational study.

PATIENT SAMPLE

Four hundred forty-five patients who underwent surgical decompression for DLSS.

OUTCOME MEASURES

Treatment failure (defined as conversion to a fusion of a previously decompressed level) of lumbar decompression.

MATERIALS AND METHODS

Several risk factors associated with worse outcomes and treatment failures, such as age, body mass index, smoking status, previous surgery, low back pain (LBP), facet joint effusion, disk degeneration, fatty infiltration of the paraspinal muscles, the presence of degenerative spondylolisthesis and the facet angulation, were investigated.

RESULTS

At a mean follow-up of 44±31 months, 6.5% (29/445) of the patients underwent revision surgery with spinal fusion at an average of 3±9 months following the lumbar decompression due to low back or leg pain. The baseline LBP (≥7) [odds ratio (OR)=5.4, P <0.001], the presence of facet joint effusion (>2 mm) in magnetic resonance imaging (OR=4.2, P <0.001), and disk degeneration (Pfirrmann >4) (OR=3.2, P =0.03) were associated with an increased risk for treatment failure following decompression for DLSS. The receiver operating characteristic curve analysis demonstrated that a score≥6 points yielded a sensitivity of 90% and specificity of 64% for predicting a treatment failure following lumbar decompression for DLSS in the present cohort.

CONCLUSIONS

The newly introduced score quantifying amounts of LBP, facet effusions, and disk degeneration, could predict treatment failure and the need for revision surgery for DLSS patients undergoing lumbar decompression without fusion. Patients with scores >6 have a high chance of needing fusion following decompression surgery.

LEVEL OF EVIDENCE

Retrospective observational study, Level III.

Role of C-reactive protein in the bone marrow of Modic type 1 changes

Modic type 1 changes (MC1) are vertebral bone marrow lesions and associate with low back pain. Increased serum C-reactive protein (CRP) has inconsistently been associated with MC1. We aimed to provide evidence for the role of CRP in the tissue pathophysiology of MC1 bone marrow. From 13 MC1 patients undergoing spinal fusion at MC1 levels, vertebral bone marrow aspirates from MC1 and intrapatient control bone marrow were taken. Bone marrow CRP, interleukin (IL)-1, and IL-6 were measured with enzyme-linked immunosorbent assays; lactate dehydrogenase (LDH) was measured with a colorimetric assay. CRP, IL-1, and IL-6 were compared between MC1 and control bone marrow. Bone marrow CRP was correlated with blood CRP and with bone marrow IL-1, IL-6, and LDH. CRP expression by marrow cells was measured with a polymerase chain reaction. Increased CRP in MC1 bone marrow (mean difference: +0.22 mg CRP/g, 95% confidence interval [CI] [-0.04, 0.47], p = 0.088) correlated with blood CRP (r = 0.69, p = 0.018), with bone marrow IL-1β (ρ = 0.52, p = 0.029) and IL-6 (ρ = 0.51, p = 0.031). Marrow cells did not express CRP. Increased LDH in MC1 bone marrow (143.1%, 95% CI [110.7%, 175.4%], p = 0.014) indicated necrosis. A blood CRP threshold of 3.2 mg/L detected with 100% accuracy increased CRP in MC1 bone marrow. In conclusion, the association of CRP with inflammatory and necrotic changes in MC1 bone marrow provides evidence for a pathophysiological role of CRP in MC1 bone marrow.

Inhibition profile of trifludimoxazin towards PPO2 target site mutations

BACKGROUND

Target site resistance to herbicides that inhibit protoporphyrinogen IX oxidase (PPO; EC 1.3.3.4) has been described mainly in broadleaf weeds based on mutations in the gene designated protoporphyrinogen oxidase 2 (PPO2) and in one monocot weed species in protoporphyrinogen oxidase 1 (PPO1). To control PPO target site resistant weeds in future it is important to design new PPO-inhibiting herbicides that can control problematic weeds expressing mutant PPO enzymes. In this study, we assessed the efficacy of a new triazinone-type inhibitor, trifludimoxazin, to inhibit PPO2 enzymes carrying target site mutations in comparison with three widely used PPO-inhibiting herbicides.

RESULTS

Mutated Amaranthus spp. PPO2 enzymes were expressed in Escherichia coli, purified and measured biochemically for activity and inhibition kinetics, and used for complementation experiments in an E. coli hemG mutant that lacks the corresponding microbial PPO gene function. In addition, we used ectopic expression in Arabidopsis and structural PPO protein modeling to support the enzyme inhibition study. The generated data strongly suggest that trifludimoxazin is a strong inhibitor both at the enzyme level and in transgenics Arabidopsis ectopically expressing PPO2 target site mutations.

CONCLUSION

Trifludimoxazin is a potent PPO-inhibiting herbicide that inhibits various PPO2 enzymes carrying target site mutations and could be used as a chemical-based control strategy to mitigate the widespread occurrence of PPO target site resistance as well as weeds that have evolved resistance to other herbicide mode of actions. © 2022 BASF SE and The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

County-Level Economic Changes and Drug Mortality in the United States: Evidence from the Great Recession

We aimed at examining whether county-level economic changes were associated with changes in county-level drug mortality rates since the Great Recession and whether the association is equally distributed across major sociodemographic subgroups. Using the Centers for Disease Control and Prevention's Wide-Ranging Online Data for Epidemiologic Research (2004-2019), combined with census data, we conducted fixed effects analyses by including county-level economic changes as primary exposures and county-level drug-related mortality rates (per 100,000 people) from 2004-2007 (i.e., prior to the recession) to 2008-2011, 2012-2015, and 2016-2019 as an outcome variable based on 1833 counties. Our findings showed that drug mortality rates increased from 13.9 (2004-2007) to 16.0 (2008-2011), 18.0 (2012-2015), and 23.0 (2016-2019). Counties experiencing smaller median household income growth during and/or after the recession were associated with greater increase in drug mortality than counties experiencing larger median household income growth among the total population and all sociodemographic subgroups. Counties experiencing larger increases in unemployment rates and percentage of vacant housing units were associated with greater increase in drug mortality than counties experiencing smaller or no increase in unemployment rates and percentage of vacant housing units among certain sociodemographic subgroups. Findings suggest the importance of local economic contexts in understanding drug mortality risk since the recession. Drug overdose prevention polices need to be formulated by taking local economic changes following a major recession into consideration.

Lumbar spinal fusion does not increase early dislocation risk in primary total hip arthroplasty through the direct anterior approach

INTRODUCTION

Patients with total hip arthroplasty (THA) and a concomitant lumbar spinal fusion (LSF) might have an increased incidence of revision surgery and postoperative complications such as early THA dislocation. The direct anterior approach (DAA) has gained popularity in THA due to its soft tissue-preserving nature and the relatively low dislocation risk. The purpose of the present study was to examine whether LSF patients undergoing minimally invasive THA through the DAA might have an increased risk of prosthetic-related complications compared to matched-control patients without a LSF.

MATERIALS AND METHODS

Patients who underwent THA through the DAA in our institution from January 2014 to December 2018 were identified. A total of 30 primary THA also underwent LSF within 3 months from the initial operation. These patients were randomly matched (1:3) for sex, age, and body mass index with patients who underwent primary THA in our institution without a history of LSF (control group). Peri and postoperative complications, revisions, radiographic and clinical outcomes were assessed retrospectively.

RESULTS

LSF patients who underwent THA through the DAA did not have an increased risk of prosthetic-related complications compared to matched-control subjects without a LSF (6.6% versus 4.4%, P < 0.05). The functional and radiological outcomes were similar between groups.

CONCLUSION

LSF patients undergoing THA could benefit from the DAA similarly to patients without LSF and without increased rate of early THA dislocation. Although the complex interplay between the lumbar spine and hip in THA patients warrants further investigation, the outcomes of THA through the DAA in LSF patients appear promising.

LEVEL OF EVIDENCE

Retrospective case-control study, III.

Involvement of glutamine synthetase 2 (GS2) amplification and overexpression in Amaranthus palmeri resistance to glufosinate

Amplification and overexpression of the target site glutamine synthetase, specifically the plastid-located isoform, confers resistance to glufosinate in Amaranthus palmeri. This mechanism is novel among glufosinate-resistant weeds. Amaranthus palmeri has recently evolved resistance to glufosinate herbicide. Several A. palmeri populations from Missouri and Mississippi, U.S.A. had survivors when sprayed with glufosinate-ammonium (GFA, 657 g ha^-1). One population, MO#2 (fourfold resistant) and its progeny (sixfold resistant), were used to study the resistance mechanism, focusing on the herbicide target glutamine synthetase (GS). We identified four GS genes in A. palmeri; three were transcribed: one coding for the plastidic protein (GS2) and two coding for cytoplasmic isoforms (GS1.1 and GS1.2). These isoforms did not contain mutations associated with resistance. The 17 glufosinate survivors studied showed up to 21-fold increase in GS2 copies. GS2 was expressed up to 190-fold among glufosinate survivors. GS1.1 was overexpressed > twofold in only 3 of 17, and GS1.2 in 2 of 17 survivors. GS inhibition by GFA causes ammonia accumulation in susceptible plants. Ammonia level was analyzed in 12 F1 plants. GS2 expression was negatively correlated with ammonia level (r =  - 0.712); therefore, plants with higher GS2 expression are less sensitive to GFA. The operating efficiency of photosystem II (ϕPSII) of Nicotiana benthamiana overexpressing GS2 was four times less inhibited by GFA compared to control plants. Therefore, increased copy and overexpression of GS2 confer resistance to GFA in A. palmeri (or other plants). We present novel understanding of the role of GS2 in resistance evolution to glufosinate.

Inhibition of acyl-ACP thioesterase as site of action of the commercial herbicides cumyluron, oxaziclomefone, bromobutide, methyldymron and tebutam

BACKGROUND

Understanding the mode and site of action of a herbicide is key for its efficient development, the evaluation of its toxicological risk, efficient weed control and resistance management. Recently, the mode of action (MoA) of the herbicide cinmethylin was identified in lipid biosynthesis with acyl-ACP thioesterase (FAT) as the site of action (SoA). Cinmethylin was registered for selective use in cereal crops for the control of grass weeds in 2020.

RESULTS

Here, we present a high-resolution co-crystal structure of FAT in complex with cumyluron identified by a high throughput crystallization screen. We show binding to and inhibition of FAT by cumyluron. Furthermore, in an array of experiments consisting of FAT binding assays, FAT inhibition assays, physiological and metabolic profiling, we tested compounds that are structurally related to cumyluron and identified the commercial herbicides oxaziclomefone, methyldymron, tebutam and bromobutide, with so far unknown sites of action, as FAT inhibitors. Additionally, we show that the previously described FAT inhibitors cinmethylin and methiozolin bind to FAT in a nanomolar range, inhibit FAT enzymatic activity and lead to similar metabolic changes.

CONCLUSION

Based on presented data, we corroborate cinmethylin and methiozolin as potent FAT inhibitors and identify FAT as the SoA of the herbicides cumyluron, oxaziclomefone, bromobutide, methyldymron and tebutam. © 2022 Society of Chemical Industry.

Incidence of Revision Surgery After Decompression With vs Without Fusion Among Patients With Degenerative Lumbar Spinal Stenosis

IMPORTANCE

Only limited data derived from large prospective cohort studies exist on the incidence of revision surgery among patients who undergo operations for degenerative lumbar spinal stenosis (DLSS).

OBJECTIVE

To assess the cumulative incidence of revision surgery after 2 types of index operations-decompression alone or decompression with fusion-among patients with DLSS.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study analyzed data from a multicenter, prospective cohort study, the Lumbar Stenosis Outcome Study, which included patients aged 50 years or older with DLSS at 8 spine surgery and rheumatology units in Switzerland between December 2010 and December 2015. The follow-up period was 3 years. Data for this study were analyzed between October and November 2021.

EXPOSURES

All patients underwent either decompression surgery alone or decompression with fusion surgery for DLSS.

MAIN OUTCOMES AND MEASURES

The primary outcome was the cumulative incidence of revision operations. Secondary outcomes included changes in the following patient-reported outcome measures: Spinal Stenosis Measure (SSM) symptom severity (higher scores indicate more pain) and physical function (higher scores indicate more disability) subscale scores and the EuroQol Health-Related Quality of Life 5-Dimension 3-Level questionnaire (EQ-5D-3L) summary index score (lower scores indicate worse quality of life).

RESULTS

A total of 328 patients (165 [50.3%] men; median age, 73.0 years [IQR, 66.0-78.0 years]) were included in the analysis. Of these, 256 (78.0%) underwent decompression alone and 72 (22.0%) underwent decompression with fusion. The cumulative incidence of revisions after 3 years of follow-up was 11.3% (95% CI, 7.4%-15.1%) for the decompression alone group and 13.9% (95% CI, 5.5%-21.5%) for the fusion group (log-rank P = .60). There was no significant difference in the need for revision between the 2 groups over time (unadjusted absolute risk difference, 2.6% [95% CI, -6.3% to 11.4%]; adjusted absolute risk difference, 3.9% [95% CI, -5.2% to 17.0%]; adjusted hazard ratio, 1.40 [95% CI, 0.63-3.13]). The number of revisions was significantly associated with higher SSM symptom severity scores (β, 0.171; 95% CI, 0.047-0.295; P = .007) and lower EQ-5D-3L summary index scores (β, -0.061; 95% CI, -0.105 to -0.017; P = .007) but not with higher SSM physical function scores (β, 0.068; 95% CI, -0.036 to 0.172; P = .20). The type of index operation was not significantly associated with the corresponding outcomes.

CONCLUSIONS AND RELEVANCE

This cohort study showed no significant association between the type of index operation for DLSS-decompression alone or fusion-and the need for revision surgery or the outcomes of pain, disability, and quality of life among patients after 3 years. Number of revision operations was associated with more pain and worse quality of life.

The effect of lumbar spinal fusion on native acetabular anteinclination in standing position

PURPOSE

The complex and dynamic spinopelvic interplay is not well understood. The aims of the present study were to investigate the following: (1) whether native acetabular anteinclination (AI) in standing position changes following lumbar spinal fusion (LSF); (2) potential correlations between AI change (ΔAI) and several spinopelvic parameters such as the change in lumbar lordosis (ΔLL), pelvic tilt (ΔPT), and anterior pelvic plane angle (ΔaPP).

METHODS

A total of 485 patients (Males: 262, Females: 223) with an average age of 64 ± 13 years who underwent a primary LSF were identified from our institutional database. The difference (Δ) between pre-and postoperative acetabular anteinclination (AI), lumbar lordosis (LL), anterior pelvic plane angle (aPP), sacral slope (SS), and pelvic tilt (PT) were measured on a standing lateral radiograph (EOS®) and compared to find the effect of LSF on the lumbopelvic geometry.

RESULTS

Following LSF, the average absolute ΔAI was 5.4 ± 4 (0 to 26)°, ΔLL: 5.5 ± 4 (0 to 27)°, ΔaPP: 5.4 ± 4 (0 to 38)°, ΔPT: 7 ± 5 (0 to 33)° and ΔSS: 5.3 ± 4 (0 to 33)°. No significant differences were observed between LSF levels. A ΔAI ≥ 10° was observed in 66 (13.6%) and ΔAI ≥ 20° in 5 (1%) patients. The Pearson correlation demonstrated a strong negative correlation of ΔAI with ΔLL (r = 0.72, p < .001).

CONCLUSION

Clinical decision-making should consider the relationship between native anteinclination and lumbar lordosis to reduce the risk of functional acetabular component malalignment in patients with concomitant hip and spine pathology.

LEVEL OF EVIDENCE

Retrospective case-control study, Level III.

Risk factors for L5 pedicle fractures after single-level posterior spinal fusion

BACKGROUND CONTEXT

Pedicle fractures are a rare but potentially devastating complication of posterior instrumented spinal fusion (PSF). Preoperative awareness of the possible risk factors may help prevent these fractures by modifying the surgical plan. However, the risk factors have not yet been identified.

PURPOSE

To determine the preoperative parameters associated with postoperative L5 pedicle fracture after L4/5 PSF.

STUDY DESIGN

Case control study.

PATIENT SAMPLE

Patients undergoing L4/5 PSF at a single academic institution between 2014 and 2020.

OUTCOME MEASURES

Occurrence of postoperative L5 pedicle fracture.

METHODS

Of 253 patients (female:male, 145:108) undergoing L4/5 PSF from 2014 to 2020, patients with postoperative L5 pedicle fractures were identified retrospectively as "cases" (n = 8, all female, age: 70 ± 10.7 years). As a control group all remaining patients with a follow-up of more than 12 months were allocated (n = 184, 104 females, age: 64.27 ± 13.00 years). In all but 16 cases, anterior support with transforaminal or posterior interbody fusion was performed. Demographic and clinical data (body mass index (BMI)), surgical factors, and comorbidities) were compared. Radiological assessment of spinopelvic parameters was performed using pre- and postoperative standing lateral radiographs.

RESULTS

The overall incidence of L5 pedicle fractures after L4/5 spinal fusion was 3.16%, with a median time from index surgery to diagnosis of 25 days (range, 6-199 days) (75% within the first 32 days postoperatively). Patients with L5 pedicle fractures had higher pelvic incidence (PI) (71° ± 9° vs. 56° ± 11°; p=.001), sacral slope (SS) (45° ± 7° vs. 35° ± 8°; p=.002), L5 slope (30° ± 11° vs. 15° ± 10°, p=.001), L5 incidence (42° ± 14° vs. 26° ± 11°; p= .003), L1-S1 lumbar lordosis (LL) postop (57° ± 10° vs. 45° ± 11°; p=.006), and L4 -S1 LL postop (33° ± 7° vs. 28° ± 7°; p=.049) compared with the control group. Pelvic tilt and PI- LL mismatch were not significantly different. Female gender was a significant risk factor for L5 pedicle fractures (p=.015). BMI (kg/m²) was statistically equal in patients with or without pedicle fractures (28.37 ± 5.96 vs. 28.53 ± 16.32; p=.857). There was no significant difference between the groups for approximative bone mineral density assessment (Hounsfield units; 113 ± 60 vs. 120 ± 43; p=.396) using the L3 trabecular region of interest (ROI) measurement. The correlation analysis demonstrated that most of the identified risk factors except for the postoperative L4-S1 lordosis show significant positive associations among each other. All eight patients in the fracture group underwent revision surgery, and the instrumented fusion was extended to the sacrum, with the addition of sacral-alar-iliac or iliac screws, in six cases.

CONCLUSIONS

L5 pedicle fractures occurred in 3% of the patients after single level L4/5 PSF. Risk factors are female gender, higher PI, SS, L5 slope, L5 incidence, and LL postop but not high BMI. These findings can be used for surgical planning and decision of fusion levels.

Can double PPO mutations exist in the same allele and are such mutants functional?

BACKGROUND

Resistance to protoporphyrinogen oxidase (PPO)-inhibiting herbicides is endowed primarily by target-site mutations at the PPX2 gene that compromise binding of the herbicide to the catalytic domain. In Amaranthus spp. PPX2, the most prevalent target mutations are deletion of the G210 codon, and the R128G and G339A substitutions. These mutations strongly affect the dynamic of the PPO2 binding pocket, resulting in reduced affinity with the ligand. Here we investigated the likelihood of co-occurrence of the most widespread target site mutations in the same PPX2 allele.

RESULTS

Plants carrying R128G+/+ ΔG210+/-, where + indicates presence of the mutation, were crossed with each other. The PPX2 of the offspring was subjected to pyrosequencing and E. coli-based Sanger sequencing to determine mutation frequencies and allele co-occurrence. The data show that R128G ΔG210 can occur in one allele only; the second allele carries only one mutation. Double mutation in both alleles is less likely because of significant loss of enzyme activity. The segregation of offspring populations derived from a cross between heterozygous plants carrying ΔG210 G399A also showed no co-occurrence in the same allele. The offspring exhibited the expected mutation distribution patterns with few exceptions.

CONCLUSIONS

Homozygous double-mutants are not physiologically viable. Double-mutant plants can only exist in a heterozygous state. Alternatively, if two mutations are detected in one plant, each mutation would occur in a separate allele. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

[18F]-sodium fluoride PET/MR for painful lumbar facet joint degeneration - a randomized controlled clinical trial

BACKGROUND CONTEXT

[18F]-sodium fluoride (NaF) PET/MR is a modern diagnostic modality for imaging increased bone turnover. Its merits in detecting painful facet joint osteoarthritis in patients with lumbar back pain are unknown.

PURPOSE

To perform a prospective randomized controlled study investigating [18F]-NaF PET/MR for detecting painful facet joints in comparison to the standard of care (SOC), including clinical examination and conventional MRI.

STUDY DESIGN/SETTING

Randomized controlled clinical study.

PATIENT SAMPLE

Thirty-nine patients.

OUTCOME MEASURES

Visual analog pain scale (VAS) before and at several time points after facet joint infiltration.

METHODS

Patients with low back pain and suspected facet joint osteoarthritis underwent lumbar [18F]-NaF PET/MR, besides conventional MRI and clinical examination. After randomization, they either received local anesthetics/ corticosteroid infiltration of facet joints as defined by clinical examination and conventional MRI (SOC), or according to the hot spots on PET/MR. VAS was documented at 15 minutes, 1 day, 1 week and 1 month after infiltration. Thirty-nine patients underwent PET/MR before the study was stopped due to new Good Manufacturing Practice requirement and new regulations by radiation protection authorities limiting staff radiation exposure during the production of this radiotracer.

RESULTS

Significant pain reduction compared to baseline was shown at every timepoint in both groups, except at 1 month after infiltration in the SOC group. Pain levels did not differ between SOC (n=17) and PET/MR patients (n=12) before infiltration and at 15 minutes, 1 day, 1 week and 1 month after infiltration. No significant correlation was detected between the sum of the PET/MR activity and the initial pain scores or relative reduction of pain after 15 minutes. The constructed study groups of patients with infiltration of all facet joints being PET/MR-positive (n=18) had significantly less pain after 1 months than patients with infiltration in PET/MR-negative facet joints (n=11) (VAS: 4 [0, 9] vs. 7 [2, 10], p=.046).

CONCLUSIONS

There is no correlation of pain to NaF activity nor a relevant superiority of [18F]-NaF PET/MR for identification of painful facet joints compared to the standard of care.

Comparison of axial and sagittal spinal cord motion measurements in degenerative cervical myelopathy

BACKGROUND AND PURPOSE

The timing of decision-making for a surgical intervention in patients with mild degenerative cervical myelopathy (DCM) is challenging. Spinal cord motion phase contrast MRI (PC-MRI) measurements can reveal the extent of dynamic mechanical strain on the spinal cord to potentially identify high-risk patients. This study aims to determine the comparability of axial and sagittal PC-MRI measurements of spinal cord motion with the prospect of improving the clinical workup.

METHODS

Sixty-four DCM patients underwent a PC-MRI scan assessing spinal cord motion. The agreement of axial and sagittal measurements was determined by means of intraclass correlation coefficients (ICCs) and Bland-Altman analyses.

RESULTS

The comparability of axial and sagittal PC-MRI measurements was good to excellent at all cervical levels (ICCs motion amplitude: .810-.940; p &lt; .001). Significant differences between axial and sagittal amplitude values could be found at segments C3 and C4, while its magnitude was low (C3: 0.07 ± 0.19 cm/second; C4: -0.12 ± 0.30 cm/second). Bland-Altman analysis showed a good agreement between axial and sagittal PC-MRI scans (coefficients of repeatability: minimum -0.23 cm/second at C2; maximum -0.58 cm/second at C4). Subgroup analysis regarding anatomic conditions (stenotic vs. nonstenotic segments) and different velocity encoding (2 vs. 3 cm/second) showed comparable results.

CONCLUSIONS

This study demonstrates good comparability between axial and sagittal spinal cord motion measurements in DCM patients. To this end, axial and sagittal PC-MRI are both accurate and sensitive in detecting pathologic cord motion. Therefore, such measures could identify high-risk patients and improve clinical decision-making (ie, timing of decompression).

Intraoperative monitoring of CSF pressure in patients with degenerative cervical myelopathy (COMP-CORD Study): a prospective cohort study

Degenerative cervical myelopathy (DCM) is hallmarked by spinal canal narrowing and related cord compression and myelopathy. CSF pressure dynamics are likely disturbed due to spinal canal stenosis. The study aims to investigate the diagnostic value of continuous intraoperative CSF pressure monitoring during surgical decompression. Prospective single center study (NCT02170155) with enrolment of DCM patients that underwent surgical decompression between December 2019 and May 2021. Data from N=17 patients were analyzed, symptom severity graded with the modified Japanese Orthopedic Score (mJOA). CSF pulsations were continuously monitored with a lumbar intrathecal catheter during surgical decompression. Mean patient age was 62±9 years (range 38-73; 8F), symptoms were mild-moderate in most patients (mean mJOA 14±2, range 10-18). Measurements were well tolerated without safety concerns. In 15/16 (94%) CSF pulsations increased at the time of surgical decompression. In one case, responsiveness could not be evaluated for technical reasons. Unexpected CSF pulsation decrease was related to adverse events (i.e., CSF leakage). Median CSF pulsation amplitudes increased from pre-decompression (0.52 mmHg [IQR 0.71]) to post-decompression (0.72 mmHg [IQR 0.96]) (P=0.001). Mean baseline CSF pressure increased with lower magnitude than pulsations, from 9.5±3.5 to 10.3±3.8 mmHg (P=0.003). Systematic relations of CSF pulsations were confined to surgical decompression, independent of arterial blood pressure (P=0.927) or heart rate (P=0.102). Intraoperative CSF pulsation monitoring was sensitive, timely, and specifically related to surgical decompression while in addition adverse events could be discerned. Further investigation of the clinical value of intraoperative guidance for decompression in complex DCM surgery is promising.

Deep surgical site infections following double-dose perioperative antibiotic prophylaxis in adult obese orthopedic patients

BACKGROUND

Obesity is a risk factor for surgical site infections (SSI). Based on retrospective comparisons and pharmacology, many orthopedic centers have adopted weight- or body mass index (BMI)-related antibiotic prophylaxis.

METHODS

Double-dose prophylaxis was introduced in March 2017 for patients weighting >80 kg. The period April 2014 to March 2017 ('before') was compared to the period March 2017 to June 2019 ('after') regarding the impact on deep SSIs.

RESULTS

A total of 9318 surgeries 'before' were compared to 7455 interventions 'after' the introduction of double-dose prophylaxis. Baseline demographic characteristics (age, sex, BMI, American Society of Anesthesiologists score, and duration of surgery) were similar. In the period 'after', 3088 cases (3088/16 773; 18%) received double-dose prophylaxis. Overall, 82 deep SSIs were observed (0.5%). The pathogens were resistant to the standard cefuroxime prophylaxis in 30 cases (30/82; 37%). Excluding these prophylaxis-resistant cases and all of the five hematogenous SSIs, the remaining 47 SSIs (57%) could have been prevented by the preceding prophylaxis. Double-dosing of parenteral cefuroxime from 1.5 g to 3.0 g in obese patients did not reduce deep SSIs (hazard ratio 0.7, 95% confidence interval 0.3-1.6). In the direct group comparison among obese patients >80 kg, the double-dose prophylaxis equally failed to alter the SSI risk (3088/16 726 non-infections vs 8/47 SSI despite double-dose prophylaxis; Chi-square test, P = 0.78).

CONCLUSIONS

In this single-center before-and-after study with almost 17 000 orthopedic surgeries in adult patients, systemic doubling of the perioperative antibiotic prophylaxis in obese patients clinically failed to reduce the overall deep SSI risk.

Pro-fibrotic phenotype of bone marrow stromal cells in Modic type 1 changes

Modic type 1 changes (MC1) are painful vertebral bone marrow lesions frequently found in patients suffering from chronic low-back pain. Marrow fibrosis is a hallmark of MC1. Bone marrow stromal cells (BMSCs) are key players in other fibrotic bone marrow pathologies, yet their role in MC1 is unknown. The present study aimed to characterise MC1 BMSCs and hypothesised a pro-fibrotic role of BMSCs in MC1. BMSCs were isolated from patients undergoing lumbar spinal fusion from MC1 and adjacent control vertebrae. Frequency of colony-forming unit fibroblast (CFU-F), expression of stem cell surface markers, differentiation capacity, transcriptome, matrix adhesion, cell contractility as well as expression of pro-collagen type I alpha 1, α-smooth muscle actin, integrins and focal adhesion kinase (FAK) were compared. More CFU-F and increased expression of C-X-C-motif-chemokine 12 were found in MC1 BMSCs, possibly indicating overrepresentation of a perisinusoidal BMSC population. RNA sequencing analysis showed enrichment in extracellular matrix proteins and fibrosis-related signalling genes. Increases in pro-collagen type I alpha 1 expression, cell adhesion, cell contractility and phosphorylation of FAK provided further evidence for their pro-fibrotic phenotype. Moreover, a leptin receptor high expressing (LEPRhigh) BMSC population was identified that differentiated under transforming growth factor beta 1 stimulation into myofibroblasts in MC1 but not in control BMSCs. In conclusion, pro-fibrotic changes in MC1 BMSCs and a LEPRhigh MC1 BMSC subpopulation susceptible to myofibroblast differentiation were found. Fibrosis is a hallmark of MC1 and a potential therapeutic target. A causal link between the pro-fibrotic phenotype and clinical characteristics needs to be demonstrated.

Biomechanical performance of bicortical versus pericortical bone trajectory (CBT) pedicle screws

PURPOSE

The cortical bone trajectory (CBT) is an alternative to the traditional pedicle screw trajectory (TT) in posterior spinal instrumentation, enhancing screw contact with cortical bone and therefore increasing fixation strength. Additional to the trajectory, insertion depth (pericortical vs. bicortical placement) could be a relevant factor affecting the fixation strength. However, the potential biomechanical benefit of a bicortical placement of CBT screws is unknown. Therefore, the aim of this study was to quantify the fixation strength of pericortical- versus bicortical-CBT (pCBT versus bCBT) screws in a randomized cadaveric study.

METHODS

Pedicle screws were either placed pericortical or bicortical with a CBT in 20 lumbar vertebrae (2 × 20 instrumented pedicles) from four human spine cadavers by using patient-specific templates. Instrumented specimens underwent physiological cyclic loading testing (1'800'000 cycles, 10 Hz), including shear and tension loads as well as bending moments. Translational and angular displacements of the screws were quantified and compared between the two techniques.

RESULTS

There was a slight decrease in translational (0.2 mm ± 0.09 vs. 0.24 mm ± 0.11) and angular displacements (0.06° ± 0.05 vs. 0.13° ± 0.11) of bCBT screws when compared with pCBT screws after 1'800'000 cycles. However, the results were non-significant (p > 0.05).

CONCLUSION

The authors do not recommend placing CBT screws bicortically, as no relevant biomechanical advantage is gained while the potential risk for iatrogenic injury to structures anterior to the spine is increased.

OP0083 INFECTIOUS AND AUTOINFLAMMATORY MODIC TYPE 1 CHANGES HAVE DIFFERENT PATHOMECHANISMS

Background:

Modic type 1 changes (MC1) are vertebral bone marrow (BM) edema that associate with non-specific low back pain (LBP). Two etiologies have been described. In the infectious etiology the anaerobic aerotolerant Cutibacterium acnes (C. acnes) invades damaged intervertebral discs (IVDs) resulting in disc infection and endplate damage, which leads to the evocation of an immune response. In the autoinflammatory etiology disc and endplate damage lead to the exposure of immune privileged disc cells and matrix to leukocytes, thereby evoking an immune response in the BM. Different etiologies require different treatment strategies. However, it is unknown if etiology-specific pathological mechanisms exist.

Objectives:

The aim of this study was to identify etiology-specific dysregulated pathways of MC1 and to perform in-depth analysis of immune cell populations of the autoinflammatory etiology.

Methods:

BM aspirates and biopsies were obtained from LBP patients with MC1 undergoing spinal fusion. Aspirates/biopsies were taken prior screw insertion through the pedicle screw trajectory. From each patient, a MC1 and an intra-patient control aspiration/biopsy from the adjacent vertebral level was taken. If C. acnes in IVDs adjacent to MC1 were detected by anaerobic bacterial culture, patients were assigned to the infectious, otherwise to the autoinflammatory etiology.

Total RNA was isolated from aspirates and sequenced (Novaseq) (infectious n=3 + 3, autoinflammatory n=5 + 5). Genes were considered as differentially expressed (DEG) if p-value < 0.01 and log2fc > ± 0.5. Gene ontology (GO) enrichment was performed in R (GOseq), gene set enrichment analysis (GSEA) with GSEA software.

Changes in cell populations of the autoinflammatory etiology were analyzed with single cell RNA sequencing (scRNAseq): Control and MC1 biopsies (n=1 + 1) were digested, CD45+CD66b- mononuclear cells isolated with fluorescence activated cell sorting (FACS), and 10000 cells were sequenced (10x Genomics). Seurat R toolkit was used for quality-control, clustering, and differential expression analysis.

Transcriptomic changes (n=5 + 5) of CD45+CD66b+ neutrophils isolated with flow cytometry from aspirates were analyzed as for total bulk RNAseq. Neutrophil activation (n=3 + 3) was measured as CD66b+ expression with flow cytometry. CD66bhigh and CD66blow fractions in MC1 and control neutrophils were compared with paired t-test.

Results:

Comparing MC1 to control in total bulk RNAseq, 204 DEG in the autoinflammatory and 444 DEG in the infectious etiology were identified with only 67 shared genes (Fig. 1a). GO enrichment revealed “T-cell activation” (p = 2.50E-03) in the autoinflammatory and “complement activation, classical pathway” (p=1.1E-25) in the infectious etiology as top enriched upregulated biological processes (BP) (Fig 1b). ScRNAseq of autoinflammatory MC1 showed an overrepresentation of T-cells (p= 1.00E-34, OR=1.54) and myelocytes (neutrophil progenitor cells) (p=4.00E-05, OR=2.27) indicating an increased demand of these cells (Fig. 1c). Bulk RNAseq analysis of neutrophils from the autoinflammatory etiology revealed an activated, pro-inflammatory phenotype (Fig 1d), which was confirmed with more CD66bhigh neutrophils in MC1 (+11.13 ± 2.71%, p=0.02) (Fig. 1e).

Figure 1.

(a) Venn diagram of DEG from total bulk RNAseq (b) Top enriched upregulated BP of autoinflammatory (left) and infectious (right) etiology (c) Cell clustering of autoinflammatory MC1 BM (d) Enrichment of “inflammatory response” gene set in autoinflammatory MC1 neutrophils (e) Representative histogram of CD66b+ expression in MC1 and control neutrophils.

Conclusion:

Autoinflammatory and infectious etiologies of MC1 have different pathological mechanisms. T-cell and neutrophil activation seem to be important in the autoinflammatory etiology. This has clinical implication as it could be explored for diagnostic approaches to distinguish the two MC1 etiologies and supports developing targeted treatments for both etiologies.

Disclosure of Interests:

None declared

Osteoarticular infections: a specific program for older patients?

BACKGROUND

With the increasing number of elderly patients, arthroplasties, fractures and diabetic foot infections, the worldwide number of osteoarticular infections (OAI) among the elderly is concomitantly expected to rise.

AIMS

We explore existing scientific knowledge about OAI in the frail elderly population.

METHODS

We performed a literature search linking OAIs to geriatric patients and comparing elderly patients (> 65 years) with average adults (range 18-65 years).

RESULTS

In this literature, financial aspects, comparison of diverse therapies on quality of life, reimbursement policies, or specific guidelines or nursing recommendations are missing. Age itself was not an independent factor related to particular pathogens, prevention of OAI, nursing care, and outcomes of OAI. However, geriatric patients were significantly more exposed to adverse events of therapy. They had more co-morbidities and more conservative surgery for OAI.

CONCLUSION

Available literature regarding OAI management among elderly patients is sparse. In recent evaluations, age itself does not seem an independent factor related to particular epidemiology, pathogens, prevention, nursing care, rehabilitation and therapeutic outcomes of OAI. Future clinical research will concern more conservative surgical indications, but certainly reduce inappropriate antibiotic use.

Reducing the kyphosis effect of anterior short thoracolumbar/lumbar scoliosis correction with an autograft fulcrum effect

Background

Anterior scoliosis correction is a powerful technique with the disadvantage of a kyphotic effect on lumbar and thoracolumbar curves. We aimed to investigate whether a cognizant interposition of a rib graft anteriorly and at the concave side of the scoliotic curve causes significant fulcrum effect to enforce scoliosis correction and to reduce interfusional kyphosis in anterior scoliosis corrections.

Methods

Twenty otherwise comparable patients with lumbar and thoracolumbar adolescent idiopathic scoliosis (AIS) curves undergoing anterior short scoliosis correction with (n = 10) or without (n = 10, matched for age, gender and degree of deformity) fulcrum effect were retrospectively compared by means of radiographic measurements (sagittal and coronal profile, Cobb angles and intersegmental deformity correction angles) to evaluate the effect of this modified surgical technique.

Results

The overall amount of scoliosis correction was similar with 74 and 60% of initial curves of 57° and 53° in the case and control group respectively with a mean of 3 fused segments (4 screws).

Statistically relevant differences were found for intersegmental coronal cobb angles at the apex of 20° to 3° and 17° to 9° with and without fulcrum, respectively (p < 0.05). Creation of kyphosis in the fused segments was reduced with an interfusional kyphotic sagittal cobb angle of 15° pre-operatively vs. 3° post-operatively compared to the control group (13° pre-operatively vs. 18° post-operatively), (p < 0.05).

Conclusions

Interfusional hyperkyphosis associated with anterior scoliosis correction for thoracolumbar/lumbar curves can be reduced with cognizant positioning of the bone autograft at the antero-lateral (concave) site in the intervertebral region to create a fulcrum effect.

Trial registration

Registered at swissethics: BASEC No.: 2018–00180.

The Restless Spinal Cord in Degenerative Cervical Myelopathy

BACKGROUND AND PURPOSE

The spinal cord is subject to a periodic, cardiac-related movement, which is increased at the level of a cervical stenosis. Increased oscillations may exert mechanical stress on spinal cord tissue causing intramedullary damage. Motion analysis thus holds promise as a biomarker related to disease progression in degenerative cervical myelopathy. Our aim was characterization of the cervical spinal cord motion in patients with degenerative cervical myelopathy.

MATERIALS AND METHODS

Phase-contrast MR imaging data were analyzed in 55 patients (37 men; mean age, 56.2 [SD,12.0] years; 36 multisegmental stenoses) and 18 controls (9 men, P = .368; mean age, 62.2 [SD, 6.5] years; P = .024). Parameters of interest included the displacement and motion pattern. Motion data were pooled on the segmental level for comparison between groups.

RESULTS

In patients, mean craniocaudal oscillations were increased manifold at any level of a cervical stenosis (eg, C5 displacement: controls [n = 18], 0.54 [SD, 0.16] mm; patients [n = 29], monosegmental stenosis [n = 10], 1.86 [SD, 0.92] mm; P < .001) and even in segments remote from the level of the stenosis (eg, C2 displacement: controls [n = 18], 0.36 [SD, 0.09] mm; patients [n = 52]; stenosis: C3, n = 21; C4, n = 11; C5, n = 18; C6, n = 2; 0.85 [SD, 0.46] mm; P < .001). Motion at C2 differed with the distance to the next stenotic segment and the number of stenotic segments. The motion pattern in most patients showed continuous spinal cord motion throughout the cardiac cycle.

CONCLUSIONS

Patients with degenerative cervical myelopathy show altered spinal cord motion with increased and ongoing oscillations at and also beyond the focal level of stenosis. Phase-contrast MR imaging has promise as a biomarker to reveal mechanical stress to the cord and may be applicable to predict disease progression and the impact of surgical interventions.

Functional PPO2 mutations: co-occurrence in one plant or the same ppo2 allele of herbicide-resistant Amaranthus palmeri in the US mid-south

BACKGROUND

Protoporphyrinogen IX oxidase 2 (PPO2) inhibitors are important for the management of glyphosate- and acetolactate synthase-resistant Palmer amaranth [Amaranthus palmeri (S.) Wats.]. The evolving resistance to PPO inhibitors is of great concern. We surveyed the evolution of resistance to fomesafen in the US Mid-south and determined its correlation with the known functional PPO2 target-site mutations (TSM).

RESULTS

The 167 accessions analyzed were grouped into five categories, four resistant (147) and one susceptible (20). Arkansas accessions constituted 100% of the susceptible group while the Missouri accessions comprised 60% of the most resistant category. The majority of Mississippi accessions (88%) clustered in the high-survival-high-injury category, manifesting an early-stage resistance evolution. One hundred and fifteen accessions were genotyped for four known TSMs; 74% of accessions carried at least one TSM. The most common single TSM was ΔG210 (18% of accessions) and the predominant double mutation was ΔG210 + G399A (17%). Other mutations are likely less favorable, hence are rare. All TSMs were detected in three accessions. Further examination revealed that 9 and two individuals carried G399A + G210 and G399A + R128G TSM in the same allele, respectively. The existence of these combinations is supported by molecular modeling.

CONCLUSIONS

Resistance to PPO inhibitors is widespread across the Mid-southern USA. Highly resistant field populations have plants with multiple mutations. G399A is the most prone to co-occur with other ppo2 mutations in the same allele. Mutation at R128 in the configuration of the PPO2 catalytic domain restrains the co-occurrence of R128G with ΔG210, making ΔG210 + G399A the most plausible, tolerable functional mutation combination to co-occur in the same ppo2 allele.

Study protocol for an observational study of cerebrospinal fluid pressure in patients with degenerative cervical myelopathy undergoing surgical deCOMPression of the spinal CORD: the COMP-CORD study

INTRODUCTION

Degenerative cervical myelopathy (DCM) is a disabling spinal disorder characterised by sensorimotor deficits of upper and lower limbs, neurogenic bladder dysfunction and neuropathic pain. When suspected, cervical MRI helps to reveal spinal cord compression and rules out alternative diagnoses. However, the correlation between radiological findings and symptoms is weak. Cerebrospinal fluid pressure (CSFP) analysis may complement the appreciation of cord compression and be used for intraoperative and postoperative monitorings in patients undergoing surgical decompression.

METHODS AND ANALYSIS

Twenty patients diagnosed with DCM undergoing surgical decompression will receive standardised lumbar CSFP monitoring immediately before, during and 24 hours after operation. Rest (ie, opening pressure, CSF pulsation) and stimulated (ie, Valsalva, Queckenstedt's) CSFP-findings in DCM will be compared with 20 controls and results from CSFP monitoring will be related to clinical and neurophysiological findings. Arterial blood pressure will be recorded perioperatively and postoperatively to calculate spinal cord perfusion pressure and spinal vascular reactivity index. Furthermore, measures of CSFP will be compared with markers of spinal cord compression by means of MR imaging.

ETHICS AND DISSEMINATION

The study protocol conformed to the latest revision of the Declaration of Helsinki and was approved by the local Ethics Committee of the University Hospital of Zurich (KEK-ZH number PB-2016-00623). The main publications from this study will cover the CSFP fluid dynamics and pressure analysis preoperative, perioperative and postoperative correlated with imaging, clinical scores and neurophysiology. Other publications will deal with preoperative and postoperative spinal perfusion. Furthermore, we will disseminate an analysis on waveform morphology and the correlation with blood pressure and ECG. Parts of the data will be used for computational modelling of cervical stenosis.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT02170155).

The Shale Boom and Family Structure: Oil and Gas Employment Growth's Relationship to Marriage, Divorce, and Cohabitation

Shale oil and gas extraction technology has caused a large shift in the United States energy landscape over the last decade. This has had a wide range of impacts on the mostly rural communities in which oil and gas extraction occurs. While many studies have focused on the economic and environmental impact of shale development, researchers have only begun to study the social changes brought on by shale resource extraction. We examine the influence of shale oil and gas employment as a share of overall county employment on county marriage, divorce, and cohabitation rates. We find evidence that oil and gas employment growth is associated with decreased marriage rates and increased divorce rates from 2009-2014. We test several channels through which oil and gas development may influence marriage behaviors and find that changes in female labor force participation, county sex ratios, and median household incomes are associated with oil and gas development. We also test for differences across the rural/urban continuum and find that our results are driven largely by nonmetro counties.

THU0451 CELL-MATRIX ADHESION OF BONE MARROW STROMAL CELLS IN MODIC TYPE 1 CHANGES IS INCREASED AND RELATES TO INCREASED EXPRESSION OF INTEGRIN Β1

Background:

Modic type 1 changes (MC1) are vertebral bone marrow lesions associated with non-specific low back pain (LBP). The pathophysiology of MC1 includes inflammation, fibrosis, and high bone turnover. Bone marrow stromal cells (BMSCs) are key regulators of these processes: BMSCs contribute to inflammation by regulating myelopoiesis/osteoclastogenesis; BMSCs can differentiate into osteoblasts contributing to high bone turnover, and BMSCs can differentiate into pro-fibrotic myofibroblasts.

Objectives:

To identify dysregulated biological processes in MC1 BMSCs contributing to the pathobiology of MC1.

Methods:

Bone marrow aspirates were obtained from LBP patients with MC1 undergoing lumbar spinal fusion. Aspirates were taken prior to screw insertion. From each patient, a MC1 and a healthy control (HC) aspirate from the adjacent vertebral body was collected. BMSCs were isolated by plastic adherence and expanded. RNA from BMSCs passage 3 was sequenced (n=3 + 3) (Illumina Novaseq) and gene ontology of significantly dysregulated genes (p-value < 0.05) was analyzed. Specificity and rate of BMSC matrix adhesion were quantified: BMSCs (n=8 + 8) were seeded on fibronectin-coated, collagen-I-coated, and non-coated plastic dishes. BMSC adhesion was evaluated from 15min to 30min (Δ 30min - 15min). Percentage of adherent cells of MC1 and HC BMSC was compared with paired t-test. In order to identify integrins responsible for dysregulated cell-matrix adhesion, gene expression of 15 relevant integrins was measured by quantitative real-time PCR (qPCR). Normalized expressions were compared between MC1 and HC BMSC with paired t-test. Integrin β1 protein level was semi quantitatively analyzed by Western Blot (n = 5 + 5) and normalized to β-Actin expression.

Results:

By RNA sequencing, 154 genes were differentially expressed between MC1 and HC BMSCs (p-value ≤ 0.01; log2-ratio ≥ 0.5). Gene ontology enrichment analysis revealed an overrepresentation of the biological process “cell-matrix adhesion” among all significantly regulated genes (p-value < 9.3e-13). A change in cell adhesion was corroborated with adhesion assay. Binding (Δ 30min - 15min) to collagen I (MC1 + 16%, HC +10%, p-value = 0.10), fibronectin (MC1 + 17%, HC +6%, p-value = 0.03), and non-coated surface (MC1 + 46%, HC +35%, p-value = 0.05) was increased in MC1 (Figure 1). Integrin gene expression analysis revealed significant upregulation of integrin beta-1 gene (ITGB1) in MC1 vs. HC (fold change = 1.24, p-value = 0.047), whereas there was no significant difference between the other integrins tested. On protein level, integrin β1 was upregulated in MC1 in four out of five patients (Figure 2).

Figure 1.

Adhesion assay.

Figure 2.

Western Blot analysis.

Conclusion:

Adhesion of BMSCs to matrix and integrin β1 expression are increased in MC1. Integrin β1 is essential for cell-matrix adhesion and an important contributor to the initiation and progression of tissue fibrosis, a hallmark of MC1. Therefore, BMSCs and integrin β1 might be relevant novel targets for the treatment of MC1.

Disclosure of Interests: :

Irina Heggli: None declared, Susanne Epprecht: None declared, Tamara Mengis: None declared, Astrid Juengel: None declared, Michael Betz: None declared, Jose Spirig: None declared, Florian Wanivenhaus: None declared, Florian Brunner: None declared, Mazda Farshad: None declared, Oliver Distler Grant/research support from: Grants/Research support from Actelion, Bayer, Boehringer Ingelheim, Competitive Drug Development International Ltd. and Mitsubishi Tanabe; he also holds the issued Patent on mir-29 for the treatment of systemic sclerosis (US8247389, EP2331143)., Consultant of: Consultancy fees from Actelion, Acceleron Pharma, AnaMar, Bayer, Baecon Discovery, Blade Therapeutics, Boehringer, CSL Behring, Catenion, ChemomAb, Curzion Pharmaceuticals, Ergonex, Galapagos NV, GSK, Glenmark Pharmaceuticals, Inventiva, Italfarmaco, iQvia, medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Roche, Sanofi and UCB, Speakers bureau: Speaker fees from Actelion, Bayer, Boehringer Ingelheim, Medscape, Pfizer and Roche, Stefan Dudli: None declared

A novel mutation A212T in chloroplast Protoporphyrinogen oxidase (PPO1) confers resistance to PPO inhibitor Oxadiazon in Eleusine indica

BACKGROUND

Protoporphyrinogen oxidase (PPO) with two isoforms, chloroplast-targeted (PPO1) and mitochondrial-targeted (PPO2), catalyzes a step in the biosynthesis of chlorophyll and heme. PPO1 and PPO2 are herbicide target sites of PPO-inhibiting herbicides. Target-site mutations conferring resistance to PPO inhibitors have all thus far been in PPO2. Oxadiazon is a unique PPO inhibitor utilized for preemergence Eleusine indica control. In this research, we evaluated the response of two previously confirmed oxadiazon-resistant and susceptible E. indica biotypes to other PPO inhibitors and identified the resistance mechanism in two oxadiazon-resistant E. indica biotypes.

RESULTS

Two E. indica biotypes were resistant to oxadiazon, but not to other structurally unrelated PPO inhibitors, such as lactofen, flumioxazin and sulfentrazone. A novel mutation A212T was identified in the chloroplast-targeted PPO1, conferring resistance to oxadiazon in a heterologous expression system. Computational structural modeling provided a mechanistic explanation for reduced herbicide binding to the variant protein: the presence of a methyl group of threonine 212 changes the PPO1 active site and produces repulsive electrostatic interactions that repel oxadiazon from the binding pocket.

CONCLUSION

The novel A212T mutation in PPO1 conferring resistance specifically to PPO inhibitor oxadiazon was characterized. This is the first evidence of the direct role of PPO1 in the PPO mode of action, and the first evidence of evolved resistance in PPO1. © 2019 Society of Chemical Industry.

Clinical and structural outcome 20 years after repair of massive rotator cuff tears

BACKGROUND

Short- and mid-term outcomes after massive cuff tear repair are well reported, but there is no documentation of the clinical and structural outcomes at 20 years of follow-up. The hypothesis of the present study was that at 20 years, deterioration of the shoulder would have occurred and led to a substantial number of reoperations.

METHODS

The authors retrospectively recalled all 127 patients operated for massive rotator cuff tears in 1994 at 6 different centers. At the 20-year follow-up, 26 patients died and 35 were lost to follow-up. Thirteen (10.2%) had been reoperated. This left 53 patients for personal clinical assessment. Forty-nine consented to standardized radiographic evaluation for assessment of osteoarthritis, 36 patients underwent magnetic resonance imaging, allowing assessment of tendon healing, atrophy, and fatty infiltration (FI) of the cuff muscles.

RESULTS

The final Constant-Murley score (CS) was 68 ± 17.7 (range, 8-91) vs. 44 ± 15.3 (range, 13-74) preoperatively (P < .05). The final Subjective Shoulder Value (SSV) was 73% ± 23% (range, 0-100). Retears (Sugaya IV and V) were found in 17 cases (47%). Nine patients (17%) had cuff tear arthropathy (Hamada stage 4). The CS and SSV for the shoulders with FI stages III or IV were significantly inferior (53 ± 19 points and 65% ± 14% respectively) than for those with FI stages 0-II (respectively, 71.6 ± 6 points and 73% ± 4%) (P < .05).

CONCLUSIONS

Twenty years after surgical repair of massive rotator cuff tears, the functional scores remain satisfactory, and the rate of revision is low.

Short postsurgical antibiotic therapy for spinal infections: protocol of prospective, randomized, unblinded, noninferiority trials (SASI trials)

BACKGROUND

There are several open scientific questions regarding the optimal antibiotic treatment of spinal infections (SIs) with or without an implant. The duration of postsurgical antibiotic therapy is debated.

METHODS

We will perform two unblinded randomized controlled trials (RCTs). We hypothesize that shorter durations of systemic antibiotic therapy after surgery for SI are noninferior (10% margin, 80% power, α = 5%) to existing (long) treatment durations. The RCTs allocate the participants to two arms of 2 × 59 episodes each: 3 vs. 6 weeks of targeted postsurgical systemic antibiotic therapy for implant-free SIs or 6 vs. 12 weeks for implant-related SIs. This equals a total of 236 adult SI episodes (randomization scheme 1:1) with a minimal follow-up of 12 months. All participants receive concomitant multidisciplinary surgical, re-educational, internist, and infectious disease care. We will perform three interim analyses that are evaluated, in a blinded analysis, by an independent study data monitoring committee. Besides the primary outcome of remission, we will also assess adverse events of antibiotic therapy, changes of the patient's nutritional status, the influence of immune suppression, total costs, functional scores, and the timely evolution of the (surgical) wounds. We define infection as the presence of local signs of inflammation (pus, wound discharge, calor, and rubor) together with microbiological evidence of the same pathogen(s) in at least two intraoperative samples, and we define remission as the absence of clinical, laboratory, and/or radiological evidence of (former or new) infection.

DISCUSSION

Provided that there is adequate surgical debridement, both RCTs will potentially enable prescription of less antibiotics during the therapy of SI, with potentially less adverse events and reduced overall costs.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04048304. Registered on 5 August 2019.

PROTOCOL VERSION

2, 5 July 2019.

No benefit of early versus late ambulation after incidental durotomy in lumbar spine surgery: a randomized controlled trial

PURPOSE

Incidental durotomy (ID) is a complication occurring in 4-17% of decompressive spinal surgeries. Persisting CSF leakage can occur even after ID repair and requires revision surgery. Prolonged flat bed rest (BR) to reduce the incidence of persisting CSF leakage is frequently applied but highly debated. A randomized controlled trial comparing prolonged BR versus early ambulation after ID repair is lacking. The aim of this study was to investigate the incidence of revision surgery as a result of persistent cerebro-spinal fluid (CSF) leakage and medical complications after immediate or late post-operative ambulation following ID during decompressive spinal surgery.

METHODS

Ninety-four of 1429 consecutive cases undergoing lumbar spine surgery (6.58%) were complicated by an ID. Sixty patients (mean age of 64 ± 13.28 years) were randomized to either early post-operative ambulation (EA, n = 30) or flat BR for 48 h (BR, n = 30). The incidence of CSF leakage resulting in revision surgery, medical complications and duration of hospitalization were compared between groups.

RESULTS

Two patients in the BR group and two patients in the EA group underwent revision surgery as a result of persisting CSF leakage. Four patients in the BR group experienced medical complications associated with prolonged immobilization. The duration of hospitalization was 7.25 ± 3.0 days in the BR group versus 6.56 ± 2.64 days in the EA group, p = 0.413.

CONCLUSION

The results of this study indicate no benefit of prolonged BR after an adequately repaired ID in lumbar spine surgery.

LEVEL OF EVIDENCE

Level 1b (individual randomized controlled trial). These slides can be retrieved under Electronic Supplementary Material.

Clinical and radiological outcomes of osteoarthritis twenty years after rotator cuff repair

PURPOSE

Outcomes of open or arthroscopic rotator cuff repairs are well reported in the literature. The purpose of the study was to evaluate the prevalence and clinical impact of osteoarthritis 20 years following rotator cuff repair. The hypothesis was that, at long follow-up, most shoulders would have developed gleno-humeral osteoarthritis.

METHODS

The authors retrospectively recalled all 322 patients, operated for rotator cuff tears in 1994 at 6 different centres, for clinical and radiographic assessment. At 20 years of follow-up, 24 were re-operated (5 arthroplasty) and 53.4% were lost to follow-up. This left 126 patients, had been clinically assessed, had Magnetic Resonance Images (MRI) that allowed anatomic assessment of tendon healing (Sugaya), fatty infiltration (Goutallier), and X rays in order to analyse arthritis without head migration (Samilson) and with head migration (Hamada and Fukuda). Only patients with complete data were selected.

RESULTS

Mean aged was 52.3 years (25.3-68.6) at index operation. The Constant score was 45.3±19.6 preoperatively to 67.4±18.7 points at 20 years. The SSV was 73.5±21 postoperatively. The rate of osteoarthritis was 29%. Osteoarthritis was associated with a significant inferior Constant score compared to the non-arthritic group (61 versus 71 points, p=0.02), mainly due to a significant lower strength (5.4 versus 8.7 points, p=0.007). Massive rotator cuff tears were significantly associated with a higher rate of osteoarthritis. Only 4,8% patients after cuff repear needed a reverse shoulder arthroplasty. Significantly less osteoarthritis was observed when the rotator cuff repair remained intact. Suprasupinatus retear had a significant influence on fatty infiltration of the infrasupinatus muscle and on the progression towards osteoarthritis.

CONCLUSION

Twenty years after open rotator cuff repair, the rate of osteoarthritis was 29%. Massive rotator cuff tears were significantly associated with a higher rate of osteoarthritis. Less osteoarthritis was observed when suprasupinatus healed.

LEVEL OF EVIDENCE

IV.

Accuracy of Patient-Specific Template-Guided Versus Freehand Cervical Pedicle Screw Placement from C2 to C7: A Randomized Cadaveric Study

BACKGROUND

Dorsal spinal instrumentation with cervical pedicle screws (CPS) and rod constructs is performed for numerous pathologies of the cervical spine, although technically demanding. Screw misplacement is biomechanically disadvantageous and carries the risk of neurovascular sequelae. The aim of this study was to assess the accuracy of patient-specific, template-guided CPS placement from C2 to C7 compared with the freehand technique.

METHODS

Patient-specific targeting guides were used for placement of 3.5 mm CPS from C2 to C7 in 4 cadaveric specimens. Template-guided instrumentation was randomized for each cervical level and side and the contralateral side instrumented likewise but with the freehand technique. No fluoroscopy was used at all, and the spinal canal was not opened for the freehand technique. Accuracy was assessed by computed tomography, grading perforations using a 2-mm increment method, and time efficiency was compared between the 2 techniques.

RESULTS

In total, 48 screws were inserted with an equal distribution of 24 screws (50%) in each of the 2 groups. Outer pedicle width averaged 5.1 ± 1.0 mm (range 2.7-7.8); 66.7% (n = 16) of template-guided versus 20.8% (n = 5) of freehand CPS were fully contained within the pedicle (P = 0.001), whereas 91.7% (n = 22) versus 50% (n = 12) were within the <2 mm "safe" zone (P = 0.001). The mean time for instrumentation per level and side was 03:09 ± 01:37 minutes for the template-guided versus 02:32 ± 01:04 minutes for the freehand technique (P = 0.132).

CONCLUSIONS

In a cadaver model, template-guided CPS placement has a significantly greater accuracy than the freehand technique. This accuracy is comparable with navigated techniques reported in the literature.

Clinical and structural outcome twenty years after repair of isolated supraspinatus tendon tears

BACKGROUND

This study evaluated the clinical and structural outcome 20 years after repair of isolated supraspinatus tendon tears. We hypothesized that the results would deteriorate over time.

MATERIALS AND METHODS

For this retrospective multicenter study, 137 patients were recalled for a clinical and imaging assessment. Six patients (4.3%) had died from unrelated causes, 52 (38.0%) were lost to follow-up, and 13 (9.5%) had undergone reoperations. This left 66 patients for clinical evaluation. Radiographs and magnetic resonance imaging were additionally performed for 45 patients, allowing assessment of osteoarthritis, tendon healing, fatty infiltration (FI), and muscle atrophy.

RESULTS

The Constant Score (CS) improved from 51.5 ± 14.1 points preoperatively to 71 points (P < .05) with a mean Subjective Shoulder Value (SSV) of 77.2% ± 22%. Tendon discontinuity (Sugaya IV-V) was present in 19 of 45 patients (42 %), and there was advanced FI (Goutallier III-IV) of the supraspinatus in 12 (27%) and of the infraspinatus muscle in 16 (35%). Supraspinatus atrophy was present in 12 patients (28%), advanced arthritis in 6, and cuff tear arthropathy in 12 (30%). The CS and SSV were significantly inferior for shoulders with FI of stages III to IV (P < .05). The CS was lower in cuff tear arthropathy and correlated with infraspinatus FI.

CONCLUSIONS

At 20 years after surgical repair of isolated supraspinatus tears, the clinical outcome remains significantly above the preoperative state. FI of the infraspinatus is the most influential factor on long-term clinical outcome.

Stimulated two-photon emission in bulk CdSe

While two-photon emission processes are firmly established in atomic physics, their observation and use in semiconductor physics remains elusive. Here, we experimentally investigate stimulated two-photon emission in photoexcited bulk CdSe and identify requirements for the observation of stimulated two-photon emission. In particular, this process requires population inversion as well as two-photon transition energies close to the bandgap energy. In any regime investigated in the present study, net optical gain is not achieved, as the free-carrier absorption intrinsically linked to the photoexcitation completely masks the two-photon gain. The results are well in line with a recent study on nondegenerate versions of two-photon emission in GaAs and place clear limits for the practical use of two-photon emission in optically excited semiconductors.

Texture analysis of paraspinal musculature in MRI of the lumbar spine: analysis of the lumbar stenosis outcome study (LSOS) data

OBJECTIVE

To evaluate association of fatty infiltration in paraspinal musculature with clinical outcomes in patients suffering from lumbar spinal stenosis (LSS) using qualitative and quantitative grading in magnetic resonance imaging (MRI).

MATERIALS AND METHODS

In this retrospective study, texture analysis (TA) was performed on postprocessed axial T2 weighted (w) MR images at level L3/4 using dedicated software (MaZda) in 62 patients with LSS. Associations in fatty infiltration between qualitative Goutallier and quantitative TA findings with two clinical outcome measures, Spinal stenosis measure (SSM) score and walking distance, at baseline and regarding change over time were assessed using machine learning algorithms and multiple logistic regression models.

RESULTS

Quantitative assessment of fatty infiltration using the histogram TA feature "mean" showed higher interreader reliability (ICC 0.83-0.97) compared to the Goutallier staging (κ = 0.69-0.93). No correlation between Goutallier staging and clinical outcome measures was observed. Among 151 TA features, only TA feature "mean" of the spinotransverse group showed a significant but weak correlation with worsened SSM (p = 0.046). TA feature "S(3,3) entropy" showed a significant but weak association with worsened WD over 12 months (p = 0.046).

CONCLUSION

MR TA is a reproducible tool to quantitatively assess paraspinal fatty infiltration, but there is no clear association with the clinical outcome in asymptomatic LSS patients.