Fusion versus decompression alone for lumbar degenerative spondylolisthesis and spinal stenosis: a target trial emulation with index trial benchmarking.

PURPOSE: The value of adding fusion to decompression surgery for lumbar degenerative spondylolisthesis and spinal canal stenosis remains debated. Therefore, the comparative effectiveness and selected healthcare resource utilization of patients undergoing decompression with or without fusion surgery at 3 years follow-up was assessed. METHODS: Using observational data from the Lumbar Stenosis Outcome Study and a target trial emulation with index trial benchmarking approach, our study assessed the comparative effectiveness of the two main surgical interventions for lumbar degenerative spondylolisthesis-fusion and decompression alone in patients with lumbar degenerative spondylolisthesis and spinal canal stenosis. The primary outcome-measure was change in health-related quality of life (EuroQol Health Related Quality of Life 5-Dimension 3-Level questionnaire [EQ-5D-3L]); secondary outcome measures were change in back/leg pain intensity (Numeric Rating Scale), change in satisfaction (Spinal Stenosis Measure satisfaction subscale), physical therapy and oral analgesic use (healthcare utilization). RESULTS: 153 patients underwent decompression alone and 62 had decompression plus fusion. After inverse probability weighting, 137 patients were included in the decompression alone group (mean age, 73.9 [7.5] years; 77 female [56%]) and 36 in the decompression plus fusion group (mean age, 70.1 [6.7] years; 18 female [50%]). Our findings were compatible with no standardized mean differences in EQ-5D-3L summary index change score at 3 years (EQ-5D-3L German: 0.07 [95% confidence interval (CI), - 0.25 to 0.39]; EQ-5D-3L French: 0.18 [95% CI, - 0.14 to 0.50]). No between-group differences in change in back/leg pain intensity or satisfaction were found. Decompression plus fusion was associated with greater physical therapy utilization at 3 years follow-up. CONCLUSION: Decompression alone should be considered the primary option for patients with lumbar degenerative spondylolisthesis and spinal stenosis.

Characterization of hypofibrinogenemia following rattlesnake envenomation treated with crotalidae immune F(ab')2 (equine) antivenom.

INTRODUCTION: Hemotoxicity is common following rattlesnake envenomation. Published experiences with equine-derived crotalidae immune F(ab')2 antivenom have characterized hemotoxicity as delayed, recurrent, or persistent. This study investigated recovery of hypofibrinogenemia following rattlesnake envenomation treated with equine-derived crotalidae immune F(ab')2 antivenom. METHODS: This is a retrospective analysis of human rattlesnake envenomations reported to the Arizona Poison and Drug Information Center over four years. We included rattlesnake-envenomated patients who developed hypofibrinogenemia (<1,500 mg/L) and were treated with equine-derived crotalidae immune F(ab')2 antivenom. The primary outcomes were recovery period (h) and recovery rate (mg/L/h) of hypofibrinogenemia following equine-derived crotalidae immune F(ab')2 antivenom administration. Collected data included demographics, laboratory values, and antivenom administered. Statistics used were percentages, medians, and Kruskall-Wallis test. RESULTS: There were 527 rattlesnake envenomations treated with antivenom, of which 80 met the inclusion criteria. Patients receiving treatment with F(ab')2 antivenom and had a median fibrinogen concentration recovery rate of 62.3 mg/L/h (IQR: 42.0-74.3 mg/L/h) and median recovery period of 19.2 h (IQR: 13.8-26.2 h). There were statistically significant differences between categories for time to antivenom for the median recovery period (P = 0.0154). DISCUSSION: Hypofibrinogenemia is a common laboratory finding following rattlesnake envenomation in Arizona. This study investigated rattlesnake envenomated patients treated with F(ab')2 antivenom and monitored fibrinogen concentrations as a surrogate marker of venom toxicity. Additionally, time to administration of F(ab')2 antivenom was a statistical significant marker of the recovery period from hypofibrinogenemia. Limitations of this study included the geographic coverage of the poison center and exclusion of patients with insufficient laboratory monitoring or those who received another antivenom. CONCLUSIONS: Following rattlesnake envenomation in Arizona, recovery from hypofibrinogenemia was able characterized in a rate (mg/L/h) and period (h) with the quantity and time to administration of antivenom. More studies are needed to assess this finding with other antivenoms and its clinical significance.

The Expression of Toll-like Receptors in Cartilage Endplate Cells: A Role of Toll-like Receptor 2 in Pro-Inflammatory and Pro-Catabolic Gene Expression.

INTRODUCTION: The vertebral cartilage endplate (CEP), crucial for intervertebral disc health, is prone to degeneration linked to chronic low back pain, disc degeneration, and Modic changes (MC). While it is known that disc cells express toll-like receptors (TLRs) that recognize pathogen- and damage-associated molecular patterns (PAMPs and DAMPs), it is unclear if CEP cells (CEPCs) share this trait. The CEP has a higher cell density than the disc, making CEPCs an important contributor. This study aimed to identify TLRs on CEPCs and their role in pro-inflammatory and catabolic gene expression. METHODS: Gene expression of TLR1-10 was measured in human CEPs and expanded CEPCs using quantitative polymerase chain reaction. Additionally, surface TLR expression was measured in CEPs grouped into non-MC and MC. CEPCs were stimulated with tumor necrosis factor alpha, interleukin 1 beta, small-molecule TLR agonists, or the 30 kDa N-terminal fibronectin fragment. TLR2 signaling was inhibited with TL2-C29, and TLR2 protein expression was measured with flow cytometry. RESULTS: Ex vivo analysis found all 10 TLRs expressed, while cultured CEPCs lost TLR8 and TLR9 expression. TLR2 expression was significantly increased in MC1 CEPCs, and its expression increased significantly after pro-inflammatory stimulation. Stimulation of the TLR2/6 heterodimer upregulated TLR2 protein expression. The TLR2/1 and TLR2/6 ligands upregulated pro-inflammatory genes and matrix metalloproteases (MMP1, MMP3, and MMP13), and TLR2 inhibition inhibited their upregulation. Endplate resorptive capacity of TLR2 activation was confirmed in a CEP explant model. CONCLUSIONS: The expression of TLR1-10 in CEPCs suggests that the CEP is susceptible to PAMP and DAMP stimulation. Enhanced TLR2 expression in MC1, and generally in CEPCs under inflammatory conditions, has pro-inflammatory and pro-catabolic effects, suggesting a potential role in disc degeneration and MC.

SafeRPlan: Safe deep reinforcement learning for intraoperative planning of pedicle screw placement.

Spinal fusion surgery requires highly accurate implantation of pedicle screw implants, which must be conducted in critical proximity to vital structures with a limited view of the anatomy. Robotic surgery systems have been proposed to improve placement accuracy. Despite remarkable advances, current robotic systems still lack advanced mechanisms for continuous updating of surgical plans during procedures, which hinders attaining higher levels of robotic autonomy. These systems adhere to conventional rigid registration concepts, relying on the alignment of preoperative planning to the intraoperative anatomy. In this paper, we propose a safe deep reinforcement learning (DRL) planning approach (SafeRPlan) for robotic spine surgery that leverages intraoperative observation for continuous path planning of pedicle screw placement. The main contributions of our method are (1) the capability to ensure safe actions by introducing an uncertainty-aware distance-based safety filter; (2) the ability to compensate for incomplete intraoperative anatomical information, by encoding a-priori knowledge of anatomical structures with neural networks pre-trained on pre-operative images; and (3) the capability to generalize over unseen observation noise thanks to the novel domain randomization techniques. Planning quality was assessed by quantitative comparison with the baseline approaches, gold standard (GS) and qualitative evaluation by expert surgeons. In experiments with human model datasets, our approach was capable of achieving over 5% higher safety rates compared to baseline approaches, even under realistic observation noise. To the best of our knowledge, SafeRPlan is the first safety-aware DRL planning approach specifically designed for robotic spine surgery.

Pedicle Screw Placement with Augmented Reality Versus Robotic-Assisted Surgery.

STUDY DESIGN: This was a single-center prospective clinical and radiographic analysis of pedicle screw instrumentation with Robotic-assisted navigation (RAN) and augmented reality (AR). OBJECTIVE: This study aimed to compare the accuracy of lumbosacral pedicle screw placement with RAN versus AR. SUMMARY OF BACKGROUND DATA: RAN and AR have demonstrated superior accuracy in lumbar pedicle screw placement compared to conventional free-hand techniques. RAN and AR techniques both tout specific advantages over their counterparts, but to date, no study has directly compared the two technologies regarding pedicle screw accuracy. PATIENTS AND METHODS: Patients who underwent RAN or head-mounted AR navigated lumbosacral (L1-S1) pedicle screw placement for degenerative conditions were included. Screw accuracy was assessed by two independent reviewers on intraoperative 3D fluoroscopic scans using the Gertzbein and Robbins scale. A generalized linear mixed model was applied to evaluate the relationship between the screw placement technique and accuracy. RESULTS: 212 patients undergoing lumbosacral instrumentation with a total of 1,211 pedicle screws placed using RAN (n=108; screws= 827) or AR (n=104; screws= 384). Overall, Grade A was achieved in 92.6% of screws. No significant difference was found between RAN and AR screw placement regarding the incidence of accurate (Grade-A and -B screws; RAN n=824; 99.6% and AR n=379, 98.7%) versus inaccurate screws (Grade-C and -D screws; RAN n=3, 0.4% and AR n=5, 1.3%). When comparing "optimal" Grade-A screws (RAN n= 787, 95.2%, AR n=345, 89.8%) versus all other screws (B, C, and D), significantly higher accuracy was achieved using RAN (P=0.001). CONCLUSION: RAN and AR both achieved high accuracy in lumbosacral pedicle screw placement, proving reliable for this procedure. However, RAN resulted in significantly more Grade-A screw placements than AR.

Domain adaptation strategies for 3D reconstruction of the lumbar spine using real fluoroscopy data.

In this study, we address critical barriers hindering the widespread adoption of surgical navigation in orthopedic surgeries due to limitations such as time constraints, cost implications, radiation concerns, and integration within the surgical workflow. Recently, our work X23D showed an approach for generating 3D anatomical models of the spine from only a few intraoperative fluoroscopic images. This approach negates the need for conventional registration-based surgical navigation by creating a direct intraoperative 3D reconstruction of the anatomy. Despite these strides, the practical application of X23D has been limited by a significant domain gap between synthetic training data and real intraoperative images. In response, we devised a novel data collection protocol to assemble a paired dataset consisting of synthetic and real fluoroscopic images captured from identical perspectives. Leveraging this unique dataset, we refined our deep learning model through transfer learning, effectively bridging the domain gap between synthetic and real X-ray data. We introduce an innovative approach combining style transfer with the curated paired dataset. This method transforms real X-ray images into the synthetic domain, enabling the in-silico-trained X23D model to achieve high accuracy in real-world settings. Our results demonstrated that the refined model can rapidly generate accurate 3D reconstructions of the entire lumbar spine from as few as three intraoperative fluoroscopic shots. The enhanced model reached a sufficient accuracy, achieving an 84% F1 score, equating to the benchmark set solely by synthetic data in previous research. Moreover, with an impressive computational time of just 81.1 ms, our approach offers real-time capabilities, vital for successful integration into active surgical procedures. By investigating optimal imaging setups and view angle dependencies, we have further validated the practicality and reliability of our system in a clinical environment. Our research represents a promising advancement in intraoperative 3D reconstruction. This innovation has the potential to enhance intraoperative surgical planning, navigation, and surgical robotics.

Cerebrospinal fluid pressure dynamics across the intra- and postoperative setting: Retrospective study of a spine surgery cohort.

Timely and sufficient decompression are critical objectives in degenerative cervical myelopathy (DCM) and spinal cord injury (SCI). We previously investigated intraoperative cerebrospinal fluid pressure (CSFP) for determining surgical outcomes. However, confounding factors during the intra- and postoperative setting need consideration. These are related to type of respiration (i.e., artificial vs. natural) and anesthesia, which affect CSFP dynamics through the interaction between the cardiorespiratory system and the CSF compartment. This retrospective cohort study (NCT02170155) aims to systematically investigate these factors to facilitate CSFP interpretation. CSFP was continuously measured through a lumbar catheter, intra- and postoperatively, in 21 patients with DCM undergoing decompression surgery. Mean CSFP and cardiac-driven CSFP peak-to-valley amplitude (CSFPp) were analyzed throughout the perioperative period, including the immediate extubation period in eight patients. Intraoperative mean CSFP had a median value and {interquartile range} of 10.8 {5.5} mmHg and increased 1.6-fold to 16.9 {7.1} mmHg postoperatively (p < 0.001). CSFPp increased 3-fold from 0.6 {0.7} to 1.8 {2.5} mmHg (p = 0.001). Increased CSFP persisted overnight. During extubation, there was a notable increase in CSFP and CSFPp of 14.0 {5.8} and 5.1 {3.1} mmHg, respectively. From case-based analysis, this was attributed to an arterial pCO2 increase. There was no correlation between respirator settings and CSFP metrics. There were distinct and quantifiable changes in CSFP dynamics from the intra- to postoperative setting related to type of respiration, anesthesia, and level of consciousness. When monitoring CSFP dynamics in spine surgery across these settings, cardiorespiratory factors must be controlled for.

Multicenter external validation of prediction models for clinical outcomes after spinal fusion for lumbar degenerative disease.

BACKGROUND: Clinical prediction models (CPM), such as the SCOAP-CERTAIN tool, can be utilized to enhance decision-making for lumbar spinal fusion surgery by providing quantitative estimates of outcomes, aiding surgeons in assessing potential benefits and risks for each individual patient. External validation is crucial in CPM to assess generalizability beyond the initial dataset. This ensures performance in diverse populations, reliability and real-world applicability of the results. Therefore, we externally validated the tool for predictability of improvement in oswestry disability index (ODI), back and leg pain (BP, LP). METHODS: Prospective and retrospective data from multicenter registry was obtained. As outcome measure minimum clinically important change was chosen for ODI with ≥ 15-point and ≥ 2-point reduction for numeric rating scales (NRS) for BP and LP 12 months after lumbar fusion for degenerative disease. We externally validate this tool by calculating discrimination and calibration metrics such as intercept, slope, Brier Score, expected/observed ratio, Hosmer-Lemeshow (HL), AUC, sensitivity and specificity. RESULTS: We included 1115 patients, average age 60.8 ± 12.5 years. For 12-month ODI, area-under-the-curve (AUC) was 0.70, the calibration intercept and slope were 1.01 and 0.84, respectively. For NRS BP, AUC was 0.72, with calibration intercept of 0.97 and slope of 0.87. For NRS LP, AUC was 0.70, with calibration intercept of 0.04 and slope of 0.72. Sensitivity ranged from 0.63 to 0.96, while specificity ranged from 0.15 to 0.68. Lack of fit was found for all three models based on HL testing. CONCLUSIONS: Utilizing data from a multinational registry, we externally validate the SCOAP-CERTAIN prediction tool. The model demonstrated fair discrimination and calibration of predicted probabilities, necessitating caution in applying it in clinical practice. We suggest that future CPMs focus on predicting longer-term prognosis for this patient population, emphasizing the significance of robust calibration and thorough reporting.

Titanium-Coated Polyetheretherketone Cages Vs Full Titanium Cages for Stand-Alone 1- or 2-Level Anterior Cervical Discectomy and Fusion: A Comparative Study.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) for the surgical treatment of cervical degenerative disease often includes an intervertebral cage, which restores disc height and lordosis while promoting fusion . Cage materials include titanium (TTN) or polyetheretherketone (PEEK). Controversy in material selection stems from higher fusion rates with TNN, despite a higher subsidence rate, while PEEK cages demonstrate superior preservation of interspace height. Combining the advantages of both materials, TTN-coated PEEK (TCPEEK) cages were developed, featuring a PEEK core with similar stiffness to the bone, enveloped with a TTN coat, improving osteointegration. However, the potential superiority of TCPEEK over TTN cages has not been investigated. This study aimed to compare clinical and radiographic outcomes following single- or double-level ACDF using either TTN or TCPEEK cages. METHODS: This retrospective single-center study included patients undergoing single- or double-level ACDF between 2017 and 2019. Clinical outcomes included the Neck Disability Index and revision surgery incidence. Radiographic parameters included cervical and segmental lordosis, C2 to C7 sagittal vertical axis, fusion, subsidence, and adjacent segment degeneration at a minimum 12-month follow-up. RESULTS: A total of 45 patients (16 TTN; 29 TCPEEK) and 58 cervical levels (21 TTN; 37 TCPEEK) were included. Both cages significantly improved Neck Disability Index scores (TTN -10.0; TCPEEK -14.1) without significant differences. Two single-level TCPEEK patients required revision surgery due to non-union. In the radiological assessments, no significant difference was found for subsidence rates (TTN 52.4%; TCPEEK 56.8%), adjacent segment degeneration, cervical and segmental lordosis, and changes in C2 to C7 sagittal vertical axis. Though not statistically significant, fusion rates trended slightly higher with TTN (90.5%) vs TCPEEK cages (86.5%). CONCLUSION: TTN and TCPEEK cages achieve satisfactory clinical and radiological outcomes in single- or double-level ACDF. This finding suggests that the choice between them can be based on other factors, such as surgeon preference or availability, rather than specific material properties. CLINICAL RELEVANCE: This study found that the selection of ACDF cage material did not affect clinical outcomes.

Potential thresholds of critically increased cardiac-related spinal cord motion in degenerative cervical myelopathy.

Introduction: New diagnostic techniques are a substantial research focus in degenerative cervical myelopathy (DCM). This cross-sectional study determined the significance of cardiac-related spinal cord motion and the extent of spinal stenosis as indicators of mechanical strain on the cord. Methods: Eighty-four DCM patients underwent MRI/clinical assessments and were classified as MRI+ [T2-weighted (T2w) hyperintense lesion in MRI] or MRI- (no T2w-hyperintense lesion). Cord motion (displacement assessed by phase-contrast MRI) and spinal stenosis [adapted spinal canal occupation ratio (aSCOR)] were related to neurological (sensory/motor) and neurophysiological readouts [contact heat evoked potentials (CHEPs)] by receiver operating characteristic (ROC) analysis. Results: MRI+ patients (N = 31; 36.9%) were more impaired compared to MRI- patients (N = 53; 63.1%) based on the modified Japanese Orthopedic Association (mJOA) subscores for upper {MRI+ [median (Interquartile range)]: 4 (4-5); MRI-: 5 (5-5); p < 0.01} and lower extremity [MRI+: 6 (6-7); MRI-: 7 (6-7); p = 0.03] motor dysfunction and the monofilament score [MRI+: 21 (18-23); MRI-: 24 (22-24); p < 0.01]. Both patient groups showed similar extent of cord motion and stenosis. Only in the MRI- group displacement identified patients with pathologic assessments [trunk/lower extremity pin prick score (T/LEPP): AUC = 0.67, p = 0.03; CHEPs: AUC = 0.73, p = 0.01]. Cord motion thresholds: T/LEPP: 1.67 mm (sensitivity 84.6%, specificity 52.5%); CHEPs: 1.96 mm (sensitivity 83.3%, specificity 65.6%). The aSCOR failed to show any relation to the clinical assessments. Discussion: These findings affirm cord motion measurements as a promising additional biomarker to improve the clinical workup and to enable timely surgical treatment particularly in MRI- DCM patients. Clinical trial registration: www.clinicaltrials.gov, NCT02170155.

Proteomic analysis of serum in a population-based cohort did not reveal a biomarker for Modic changes.

Introduction: Modic changes (MC) are bone marrow lesions of vertebral bones, which can be detected with magnetic resonance imaging (MRI) adjacent to degenerated intervertebral discs. Defined by their appearance on T1 and T2 weighted images, there are three interconvertible types: MC1, MC2, and MC3. The inter-observer variability of the MRI diagnosis is high, therefore a diagnostic serum biomarker complementing the MRI to facilitate diagnosis and follow-up would be of great value. Methods: We used a highly sensitive and reproducible proteomics approach: DIA/SWATH-MS to find serum biomarkers in a subset of the Northern Finland Birth Cohort 1966. Separately, we measured a panel of factors involved in inflammation and angiogenesis to confirm some potential biomarkers published before with an ELISA-based method called V-Plex. Results: We found neither an association between the serum concentrations of the proteins detected with DIA/SWATH-MS with the presence of MC, nor a correlation with the size of the MC lesions. We did not find any association between the factors measured with the V-Plex and the presence of MC or their size. Conclusion: Altogether, our study suggests that a robust and generally usable biomarker to facilitate the diagnosis of MC cannot readily be found in serum.

A case report of mis-snaken identity: When misdiagnosis really bites.

When patients present with an unknown puncture wound, emergency physicians need to consider regional hazards, in addition to standard mechanical injury etiologies. In the Southwestern United States, one such hazard is the rattlesnake. In this report, we present a case in which a rattlesnake envenomation was not considered as a possible cause for a puncture wound of unknown origin, which resulted in an envenomation left untreated for 7 days. A full dry bite observation period of 12 h with serial physical exams and laboratory analysis with guidance from the region poison control center might have led to earlier recognition of an envenomation and antivenom administration. A male patient in his late 70's felt a painon his right ankle while in his backyard in southern Arizona. He did not see the cause and assumed he had sustained an insect bite. He went to the ED that day with minor pain and swelling and was discharged home. One week later, he re-presented severely anemic with edema and ecchymosis to the entire right lower extremity that developed over several days after his first ED visit. He was admitted for antivenom and blood transfusion and discharged on hospital day three. For as long as humans continue to interact with the natural world, venomous creature encounters are going to continue to happen. Rattlesnake envenomation should be included in a physician's differential diagnosis even if one is not witnessed, especially in regions with high rattlesnake activity. In addition to assessing for other potential causes of undifferentiated puncture wounds, serial physical examinations and laboratory testing (with guidance of the regional poison center) are necessary to rule out rattlesnake envenomation.

General skin and nasal decolonization with octenisan® set before and after elective orthopedic surgery in selected patients at elevated risk for revision surgery and surgical site infections-a single-center, unblinded, superiority, randomized controlled trial (BALGDEC trial).

BACKGROUND: The preoperative body surface and nasal decolonization may reduce the risk of surgical site infections (SSI) but yields conflicting results in the current orthopedic literature. METHODS: We perform a single-center, randomized-controlled, superiority trial in favor of the preoperative decolonization using a commercial product (octenidine® set). We will randomize a total number of 1000 adult elective orthopedic patients with a high risk for SSI and/or wound complications (age ≥ 80 years, chronic immune-suppression, American Society of Anesthesiologists score 3-4 points) between a decolonization (octenisan® wash lotion 1 × per day and octenisan® md nasal gel 2-3 × per day; during 5 days) and no decolonization. Decolonized patients will additionally fill a questionnaire regarding the practical difficulties, the completeness, and the adverse events of decolonization. The primary outcomes are SSI and revision surgeries for postoperative wound problems until 6 weeks postoperatively (or 1 year for surgeries with implants or bone). Secondary outcomes are unplanned revision surgeries for non-infectious problems and all adverse events. With 95% event-free surgeries in the decolonization arm versus 90% in the control arm, we formally need 2 × 474 elective orthopedic surgeries included during 2 years. DISCUSSION: In selected adult orthopedic patients with a high risk for SSI, the presurgical decolonization may reduce postoperative wound problems, including SSI. TRIAL REGISTRATION: ClinicalTrial.gov NCT05647252. Registered on 9 December 2022. PROTOCOL VERSION: 2 (5 December 2022).

Cervical kyphosis after posterior cervical laminectomy with and without fusion.

BACKGROUND: Cervical posterior instrumentation and fusion is often performed to avoid post-laminectomy kyphosis. However, larger comparative analyses of cervical laminectomy with or without fusion are sparse. METHODS: A retrospective, two-center, comparative cohort study included patients after stand-alone dorsal laminectomy with (n = 91) or without (n = 46) additional fusion for degenerative cervical myelopathy with a median follow-up of 59 (interquartile range (IQR) 52) months. The primary outcome was the C2-7 Cobb angle and secondary outcomes were Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA) scale, revision rates, T1 slope and C2-7 sagittal vertical axis (C2-7 SVA) at final follow-up. Logistic regression analysis adjusted for potential confounders (i.e. age, operated levels, and follow-up). RESULTS: Preoperative C2-7 Cobb angle and T1 slope were higher in the laminectomy group, while the C2-7 SVA was similar. The decrease in C2-7 Cobb angle from pre- to postoperatively was more pronounced in the laminectomy group (- 6° (IQR 20) versus -1° (IQR 7), p = 0.002). When adjusting for confounders, the decrease in C2-7 Cobb angle remained higher in the laminectomy group (coefficient - 12 (95% confidence interval (CI) -18 to -5), p = 0.001). However, there were no adjusted differences for postoperative NDI (- 11 (- 23 to 2), p = 0.10), mJOA, revision rates, T1 slope and C2-7 SVA. CONCLUSION: Posterior cervical laminectomy without fusion is associated with mild loss of cervical lordosis of around 6° in the mid-term after approximately five years, however without any clinical relevance regarding NDI or mJOA in well-selected patients (particularly in shorter segment laminectomies of < 3 levels).

Snake eyes: Characterization of topical ocular exposures from rattlesnakes in Arizona.

Patients occasionally present with reports of ocular exposure to fluids from rattlesnakes, claiming or suspecting the substance to be venom. This study set out to evaluate and characterize reported cases of suspected venom-induced ophthalmia in humans. A retrospective review of rattlesnake exposures reported to the Arizona Poison and Drug Information Center over a 24-year period was conducted for ocular exposures. Recorded information included patient demographics, clinical course, laboratory results, and treatments. Documentation regarding interactions between patients and snakes was reviewed by Arizona Poison and Drug Information Center herpetologists to evaluate what substance was expelled from the snake resulting in ocular exposure. Our review of rattlesnake encounters found a total of 26 ocular exposure cases. Patient demographics were largely intentional interactions and involved the male sex. Symptoms ranged from asymptomatic to minor effects with 46.2% managed from home and treated with fluid irrigation. A review of cases by herpetologists concluded the exposure patients commonly experienced was to snake musk. Kinematics of venom expulsion by rattlesnakes conclude the venom gland must be compressed, fangs erected to ≥60o, and fang sheath compressed against the roof of the mouth for venom expulsion. Evidence suggests the chance of venom "spitting" by rattlesnakes is close to zero. Rattlesnakes are documented to forcefully expel airborne malodorous "musk" defensively. An important distinction to remember is musk has a foul odor and is usually colorless, while venom is comparatively odorless and yellow. Rattlesnake venom-induced ophthalmia is a rare event as venom expulsion requires the kinematics of feeding or defensive bites. If the rattlesnake is not in the process of biting or otherwise contacting some other object with its mouth, it is more biologically plausible patients are being exposed to snake musk as a deterrent. Whether it's venom or musk, topical exposure to the eyes should prompt immediate irrigation.

Endplate weakening during cage bed preparation significantly reduces endplate load capacity.

PURPOSE: To analyze the effect of endplate weakness prior to PLIF or TLIF cage implantation and compare it to the opposite intact endplate of the same vertebral body. In addition, the influence of bone quality on endplate resistance was investigated. METHODS: Twenty-two human lumbar vertebrae were tested in a ramp-to-failure test. One endplate of each vertebral body was tested intact and the other after weakening with a rasp (over an area of 200 mm2). Either a TLIF or PLIF cage was then placed and the compression load was applied across the cage until failure of the endplate. Failure was defined as the first local maximum of the force measurement. Bone quality was assessed by determining the Hounsfield units (HU) on CT images. RESULTS: With an intact endplate and a TLIF cage, the median force to failure was 1276.3N (693.1-1980.6N). Endplate weakening reduced axial endplate resistance to failure by 15% (0-23%). With an intact endplate and a PLIF cage, the median force to failure was 1057.2N (701.2-1735.5N). Endplate weakening reduced axial endplate resistance to failure by 36.6% (7-47.9%). Bone quality correlated linearly with the force at which endplate failure occurred. Intact and weakened endplates showed a strong positive correlation: intact-TLIF: r = 0.964, slope of the regression line (slope) = 11.8, p < 0.001; intact-PLIF: r = 0.909, slope = 11.2, p = 5.5E-05; weakened-TLIF: r = 0.973, slope = 12.5, p < 0.001; weakened-PLIF: r = 0.836, slope = 6, p = 0.003. CONCLUSION: Weakening of the endplate during cage bed preparation significantly reduces the resistance of the endplate to subsidence to failure: endplate load capacity is reduced by 15% with TLIF and 37% with PLIF. Bone quality correlates with the force at which endplate failure occurs.

Feasibility of blinding spinal manual therapy interventions among participants and outcome assessors: protocol for a blinding feasibility trial.

INTRODUCTION: Blinding is a methodologically important aspect in randomised controlled trials yet frequently overlooked in trials of spinal manual therapy interventions for back pain. To help inform the blinding methods of a future, double-placebo-controlled trial comparing spinal manual therapy and nerve root injection for lumbosacral radicular pain, we set four objectives: (1) to assess the feasibility of blinding participants, randomly allocated to an active or placebo-control spinal manual therapy intervention protocol, (2) to assess the feasibility of blinding outcome assessors within the trial, (3) to explore the influence of spinal manual therapy experience and low back pain on blinding, and (4) to explore factors contributing to perceptions about intervention assignment among participants and outcome assessors. METHODS AND ANALYSIS: Two-parallel-group, single-centre, placebo-controlled, methodological blinding feasibility randomised trial. We will recruit between 60 and 100 adults with or without back pain and with or without experience of spinal manual therapy from Zurich, Switzerland. Participants will be randomised to either an active spinal manual therapy or a placebo-control spinal manual therapy protocol-both interventions delivered over two study visits, up to two weeks apart. The primary outcome is participant blinding using the Bang blinding index within each intervention arm immediately after each of the two study visits. Secondary outcomes are participant blinding using the James blinding index, outcome assessor blinding (Bang and James blinding indices), self-reported factors influencing perceived intervention assignment among participants and outcome assessors, and participant-reported credibility and expectancy of study interventions. Other outcomes-included to blind the study objective from participants-are lumbar spine range of motion, self-rated general health, satisfaction with care, pain intensity, and function. Intervention provider outcomes include intervention component fidelity and quality of intervention delivery. ETHICS AND DISSEMINATION: The independent ethics commission of Canton Zurich granted ethical approval for this study (KEK 2023-00381). Written informed consent will be obtained from all participants. Findings will be disseminated in scientific conferences and a peer-reviewed publication and inform the blinding methods of a future double-placebo controlled trial comparing spinal manual therapy and nerve root injection for lumbosacral radicular pain-the SALuBRITY trial. TRIAL REGISTRATION: NCT05778396.

Instrumentation of hypoplastic pedicles with patient-specific guides.

PURPOSE: Hypoplastic pedicles of the thoracolumbar spine (<5 mm diameter) are often found in syndromic deformities of the spine and pose a challenge in pedicle screw instrumentation. 3D-printed patient-specific guides might help overcome anatomical difficulties when instrumenting pedicles with screws, thereby reducing the necessity for less effective fixation methods such as hooks or sublaminar wires. In this study, the surgical feasibility and clinical outcome of patients with hypoplastic pedicles following pedicle screw instrumentation with 3D-printed patient-specific guides were assessed. METHODS: Hypoplastic pedicles were identified on preoperative computed tomography (CT) scans in six patients undergoing posterior spinal fusion surgery between 2017 and 2020. Based on these preoperative CT scans, patient-specific guides were produced to help with screw instrumentation of these thin pedicles. Postoperatively, pedicle-screw-related complications or revisions were analyzed. RESULTS: 93/105 (88.6%) pedicle screws placed with patient-specific guides were instrumented. 62/93 (66.7%) of these instrumented pedicles were defined as hypoplastic with a mean width of 3.07 mm (SD ±0.98 mm, 95% CI [2.82-3.32]). Overall, 6 complications in the 62 hypoplastic pedicles (9.7%) were observed and included intraoperatively managed 4 cerebrospinal fluid leaks, 1 pneumothorax and 1 delayed revision due to 2 lumbar screws (2/62, 3.3%) impinging the L3 nerve root causing a painful radiculopathy. The mean follow-up time was 26.7 (SD ±11.7) months. Complications were only noted when the pedicle-width-to-screw-diameter ratio measured less than 0.62. CONCLUSION: Patient-specific 3D-printed guides can aid in challenging instrumentation of hypoplastic pedicles in the thoracolumbar spine, especially if the pedicle-width-to-screw-diameter ratio is greater than 0.62.

Intervertebral disc microbiome in Modic changes: Lack of result replication underscores the need for a consensus in low-biomass microbiome analysis.

Introduction: The emerging field of the disc microbiome challenges traditional views of disc sterility, which opens new avenues for novel clinical insights. However, the lack of methodological consensus in disc microbiome studies introduces discrepancies. The aims of this study were to (1) compare the disc microbiome of non-Modic (nonMC), Modic type 1 change (MC1), and MC2 discs to findings from prior disc microbiome studies, and (2) investigate if discrepancies to prior studies can be explained with bioinformatic variations. Methods: Sequencing of 16S rRNA in 70 discs (24 nonMC, 25 MC1, and 21 MC2) for microbiome profiling. The experimental setup included buffer contamination controls and was performed under aseptic conditions. Methodology and results were contrasted with previous disc microbiome studies. Critical bioinformatic steps that were different in our best-practice approach and previous disc microbiome studies (taxonomic lineage assignment, prevalence cut-off) were varied and their effect on results were compared. Results: There was limited overlap of results with a previous study on MC disc microbiome. No bacterial genera were shared using the same bioinformatic parameters. Taxonomic lineage assignment using "amplicon sequencing variants" was more sensitive and detected 48 genera compared to 22 with "operational taxonomic units" (previous study). Increasing filter cut-off from 4% to 50% (previous study) reduced genera from 48 to 4 genera. Despite these differences, both studies observed dysbiosis with an increased abundance of gram-negative bacteria in MC discs as well as a lower beta-diversity. Cutibacterium was persistently detected in all groups independent of the bioinformatic approach, emphasizing its prevalence. Conclusion: There is dysbiosis in MC discs. Bioinformatic parameters impact results yet cannot explain the different findings from this and a previous study. Therefore, discrepancies are likely caused by different sample preparations or true biologic differences. Harmonized protocols are required to advance understanding of the disc microbiome and its clinical implications.

Reducing residual forces in spinal fusion using a custom-built rod bending machine.

BACKGROUND AND OBJECTIVE: As part of spinal fusion surgery, shaping the rod implant to align with the anatomy is a tedious, error-prone, and time-consuming manual process. Inadequately contoured rod implants introduce stress on the screw-bone interface of the pedicle screws, potentially leading to screw loosening or even pull-out. METHODS: We propose the first fully automated solution to the rod bending problem by leveraging the advantages of augmented reality and robotics. Augmented reality not only enables the surgeons to intraoperatively digitize the screw positions but also provides a human-computer interface to the wirelessly integrated custom-built rod bending machine. Furthermore, we introduce custom-built test rigs to quantify per screw absolute tensile/compressive residual forces on the screw-bone interface. Besides residual forces, we have evaluated the required bending times and reducer engagements, and compared our method to the freehand gold standard. RESULTS: We achieved a significant reduction of the average absolute residual forces from for the freehand gold standard to (p=0.0015) using the bending machine. Moreover, our bending machine reduced the average time to instrumentation per screw from to . Reducer engagements per rod were significantly decreased from an average of 1.00±1.14 to 0.11±0.32 (p=0.0037). CONCLUSION: The combination of augmented reality and robotics has the potential to improve surgical outcomes while minimizing the dependency on individual surgeon skill and dexterity.