Comapping Cellular Content and Extracellular Matrix with Hemodynamics in Intact Arterial Tissues Using Scanning Immunofluorescent Multiphoton Microscopy.

Deviation of blood flow from an optimal range is known to be associated with the initiation and progression of vascular pathologies. Important open questions remain about how the abnormal flow drives specific wall changes in pathologies such as cerebral aneurysms where the flow is highly heterogeneous and complex. This knowledge gap precludes the clinical use of readily available flow data to predict outcomes and improve treatment of these diseases. As both flow and the pathological wall changes are spatially heterogeneous, a crucial requirement for progress in this area is a methodology for acquiring and comapping local vascular wall biology data with local hemodynamic data. Here, we developed an imaging pipeline to address this pressing need. A protocol that employs scanning multiphoton microscopy was developed to obtain three-dimensional (3D) datasets for smooth muscle actin, collagen, and elastin in intact vascular specimens. A cluster analysis was introduced to objectively categorize the smooth muscle cells (SMC) across the vascular specimen based on SMC actin density. Finally, direct quantitative comparison of local flow and wall biology in 3D intact specimens was achieved by comapping both heterogeneous SMC data and wall thickness to patient-specific hemodynamic results.

Quantitative analysis of the nonlinear displacement-load behavior of the lumbar spine.

There is currently no universal model or fitting method to characterize the visco-elastic behavior of the lumbar spine observed in displacement versus load hysteresis loops. In this study, proposed methods for fitting these loops, along with the metrics obtained, were thoroughly analyzed. A spline fitting technique was shown to provide a consistent approximation of spinal kinetic behavior that can be differentiated and integrated. Using this tool, previously established metrics were analyzed using data from two separate studies evaluating different motion preservation technologies. Many of the metrics, however, provided no significant differences beyond range of motion analysis. Particular attention was paid to how different definitions of the neutral zone capture the high-flexibility region often seen in lumbar hysteresis loops. As a result, the maximum slope was introduced and shown to be well defined. This new parameter offers promise as a descriptive measurement of spinal instability in vitro and may have future implications in clinical diagnosis and treatment of spinal instability. In particular, it could help in assigning treatments to specific stabilizing effects in the lumbar spine.

Are carfentanil and acrylfentanyl naloxone resistant?

The rapid rise in deaths since 2012 due to opioid poisoning is correlated with the proliferation of potent synthetic opioid agonists such as fentanyl, acrylfentanyl, and carfentanil. The efficacy of frontline antidotes such as naloxone in reversing such poisoning events has been questioned, and the possibility of naloxone-resistant synthetic opioids has been raised. In this manuscript, we applied in vitro techniques to establish the median effective inhibitory concentrations for fentanyl, acrylfentanyl, and carfentanil and subsequently evaluate naloxone's ability to reverse agonist-receptor interactions.

Effect of device constraint: a comparative network meta-analysis of ACDF and cervical disc arthroplasty.

BACKGROUND CONTEXT: Clinical trials have demonstrated that cervical disc arthroplasty (CDA) is an effective and safe alternative treatment to anterior cervical discectomy and fusion (ACDF) for cervical degenerative disc disease in the appropriately indicated patient population. Various devices for CDA exist, differing in the level of device constraint. PURPOSE: To investigate outcomes following Anterior Cervical Discectomy and Fusion (ACDF) versus CDA stratified based on the level of device constraint: Constrained, Semiconstrained, and Unconstrained. STUDY DESIGN: Systematic review and network meta-analysis. PATIENT SAMPLE: 2,932 CDA patients (979 Constrained, 1,214 Semiconstrained, 739 Unconstrained) and 2,601 ACDF patients from 41 studies that compared outcomes of patients undergoing CDA or ACDF at a single level at a minimum of 2 years follow-up. OUTCOME MEASURES: Outcomes of interest included the development of adjacent segment degeneration (ASD), index and adjacent segment reoperation rates, range of motion (ROM), high-grade heterotopic ossification (HO, McAfee Grades 3/4), and patient-reported outcomes (NDI/VAS). METHODS: CDA devices were grouped based on the degrees of freedom (DoF) allowed by the device, as either Constrained (3 DoF), Semiconstrained (4 or 5 DoF), or Unconstrained (6 DoF). A random effects network meta-analysis was conducted using standardized mean differences (SMD) and log relative risk (RR) were used to analyze continuous and categorical data, respectively. RESULTS: Semiconstrained (p=.03) and Unconstrained CDA (p=.01) demonstrated a significantly lower risk for ASD than ACDF. All levels of CDA constraint demonstrated a significantly lower risk for subsequent adjacent segment surgery than ACDF (p<.001). Semiconstrained CDA also demonstrated a significantly lower risk for index level reoperation than both ACDF and Constrained CDA (p<.001). Unconstrained devices retained significantly greater ROM than both Constrained and Semiconstrained CDA (p<.001). As expected, all levels of device constraint retained significantly greater ROM than ACDF (p<.001). Constrained and Unconstrained devices both demonstrated significantly lower levels of disability on NDI than ACDF (p=.02). All levels of device constraint demonstrated significantly less neck pain than ACDF (p<.05), while Unconstrained CDA had significantly less arm pain than ACDF (p=.02) at final follow-up greater than 2 years. CONCLUSION: Cervical Disc Arthroplasty, particularly the unconstrained and semiconstrained designs, appears to be more effective than ACDF in reducing the risk of adjacent segment degeneration and the need for further surgeries, while also allowing for greater range of motion and better patient-reported outcomes. Less constrained CDA conferred a lower risk for index level reoperation, while also retaining more range of motion than more constrained devices.

Evaluation of Self-Inflicted versus Non-Self-Inflicted Gunshot Wounds and Associated Injuries Involving the Hand and Upper Extremity.

Orthopedic costs associated with gunshot wounds (GSWs) totaled approximately USD 510 million from 2005 to 2014. Previous studies have identified differences in injuries associated with self-inflicted (SI) GSWs; however, there remains a gap in understanding injury patterns. This study aims to expand upon the current literature and shed light on injury patterns and outcomes associated with SI vs. non-self-inflicted (NSI) GSWs. This is a retrospective cohort study of upper extremity GSWs from January 2012 to December 2022. Data were analyzed using the two-sample t-test, Pearson's chi-squared test, and Fisher's exact test. SI GSWs tended to be high-velocity GSWs and occurred more often in distal locations compared to NSI GSWs (p = 0.0014 and p < 0.0001, respectively). SI GSWs were associated with higher Gustilo-Anderson (GA) and Tscherne classifications (p < 0.0001 and p = 0.0048, respectively) and with a greater frequency of neurovascular damage (p = 0.0048). There was no difference in fracture rate or need for operative intervention between the groups. GA and Tscherne classifications were associated with the need for and type of surgery (p < 0.0001), with a higher classification being associated with more intricate operative intervention; however, GSW velocity was not associated with operative need (p = 0.42). Our findings demonstrate that velocity, wound grading systems, and other factors are associated with the manner in which GSWs to the upper extremity are inflicted and may thus have potential for use in the prediction of injury patterns and planning of trauma management and surgical intervention.

The Osteogenic Peptide P-15 for Bone Regeneration: A Narrative Review of the Evidence for a Mechanism of Action.

Bone regeneration is a complex multicellular process involving the recruitment and attachment of osteoprogenitors and their subsequent differentiation into osteoblasts that deposit extracellular matrixes. There is a growing demand for synthetic bone graft materials that can be used to augment these processes to enhance the healing of bone defects resulting from trauma, disease or surgery. P-15 is a small synthetic peptide that is identical in sequence to the cell-binding domain of type I collagen and has been extensively demonstrated in vitro and in vivo to enhance the adhesion, differentiation and proliferation of stem cells involved in bone formation. These events can be categorized into three phases: attachment, activation and amplification. This narrative review summarizes the large body of preclinical research on P-15 in terms of these phases to describe the mechanism of action by which P-15 improves bone formation. Knowledge of this mechanism of action will help to inform the use of P-15 in clinical practice as well as the development of methods of delivering P-15 that optimize clinical outcomes.

An Immunologic and Biomechanical Comparison of Polyether Ether Ketone-Zeolite and Polyether Ether Ketone Interbody Fusion Devices.

STUDY DESIGN: A laboratory study comparing polyether ether ketone (PEEK)-zeolite and PEEK spinal implants in an ovine model. OBJECTIVE: This study challenges a conventional spinal implant material, PEEK, to PEEK-zeolite using a nonplated cervical ovine model. SUMMARY OF BACKGROUND DATA: Although widely used for spinal implants due to its material properties, PEEK is hydrophobic, resulting in poor osseointegration, and elicits a mild nonspecific foreign body response. Zeolites are negatively charged aluminosilicate materials that are hypothesized to reduce this pro-inflammatory response when used as a compounding material with PEEK. MATERIALS AND METHODS: Fourteen skeletally mature sheep were, each, implanted with one PEEK-zeolite interbody device and one PEEK interbody device. Both devices were packed with autograft and allograft material and randomly assigned to one of 2 cervical disc levels. The study involved 2 survival time points (12 and 26 weeks) and biomechanical, radiographic, and immunologic endpoints. One sheep expired from complications not related to the device or procedure. A biomechanical evaluation was based on measures of segmental flexibility, using 6 degrees of freedom pneumatic spine tester. Radiographic evaluation was performed using microcomputed tomography scans in a blinded manner by 3 physicians. Levels of the pro-inflammatory cytokines, interleukin (IL)-1ß, IL-6, and tumor necrosis factor-alpha at the implant, were quantified using immunohistochemistry. RESULTS: PEEK-zeolite and PEEK exhibited an equivalent range of motion in flexion extension, lateral bending, and axial torsion. A motion was significantly reduced for implanted devices at both time points as compared with native segments. Radiographic assessments of fusion and bone formation were similar for both devices. PEEK-zeolite exhibited lower levels of IL-1ß ( P = 0.0003) and IL-6 ( P = 0.03). CONCLUSION: PEEK-zeolite interbody fusion devices provide initial fixation substantially equivalent to PEEK implants but exhibit a reduced pro-inflammatory response. PEEK-zeolite devices may reduce the chronic inflammation and fibrosis previously observed with PEEK devices.

Biomechanical Stability of Primary and Revision Sacroiliac Joint Fusion Devices: A Cadaveric Study.

STUDY DESIGN: An in vitro biomechanics study. OBJECTIVE: To evaluate the efficacy of triangular titanium implants in providing mechanical stabilization to a sacroiliac joint with primary and revision sized implants. METHODS: Ten lumbopelvic cadaveric specimens were tested in 4 stages: intact, pubic symphysis sectioned, primary, and simulated revision. Primary treatment was performed using 3 laterally placed triangular titanium implants. To simulate revision conditions before and after bone ingrowth and ongrowth on the implants, 7.5-mm and 10.75-mm implants were randomly assigned to one side of each specimen during the simulated revision stage. A 6 degrees of freedom spinal loading frame was used to load specimens in 4 directions: flexion extension, lateral bending, axial torsion, and axial compression. Biomechanical evaluation was based on measures of sacroiliac joint rotational and translational motion. RESULTS: Both primary and revision implants showed the ability to reduce translational motion to a level significantly lower than the intact condition when loaded in axial compression. Simulated revision conditions showed no statistically significant differences compared with the primary implant condition, with the exception of flexion-extension range of motion where motions associated with the revised condition were significantly lower. Comparison of rotational and translation motions associated with the 7.5- and 10.75-mm implants showed no significant differences between the treatment conditions. CONCLUSIONS: These results indicate that implantation of laterally placed triangular titanium implants significantly reduces the motion of a sacroiliac joint using either the primary and revision sized implants. No statistically significant differences were detected when comparing the efficacy of primary, 7.5-mm revision, or 10.75-mm revision implants.

A successful, cost-effective low back pain triage system: a pilot study.

BACKGROUND: Effective triage - directing patients with low back pain to appropriate treatment or correct referral - is fundamental to quality care. Without guidelines, a physician's initial decision may lead to unnecessary investigation, unneeded intervention or unwarranted consultation. Methods: To compare the functional outcomes of patients triaged by a classification based on clinical presentation with those of patients selected at the clinicians' discretion, an insurance-owned hospital network employed forty-seven specially-trained physical therapists, working within participating primary care practices, to classify low back pain patients into specific Patterns of Pain. Between October 2017 and April 2019, the primary care physicians used this classification, derived entirely from the patient's history and physical examination, to direct subsequent treatment for 260 consecutive low back pain patients. Patients with systemic symptoms, recent substantial trauma or non-mechanical diagnoses indicative of spinal infections or possible malignancy were excluded. Functional outcome measures were spinal imaging, opioid use, length of treatment and number of visits, back-related unplanned care, frequency of spinal surgery and back-related episode cost. These were compared with a control group of 256 propensity-matched patients and, for assessing the financial impact, with a historic cohort of 111 previously treated, non-classified patients. Results: Spinal imaging: study group 24.5%; controls 42.2% (P< .001). Narcotic use: study group 4.6%; controls 13.3% (P< .001). Treatment length: study group 62.2 days; controls 74.5 days (P=.10). Treatment visits: study group 1528 visits; controls 2,046 visits (P=.003). Unplanned care: study group 1.9%; controls 12.8% (P< .001). Spine surgery: study group 15.4%; controls 26.2% (P=.005). Episode cost: study group $1453; controls $2334 (P=.005). Conclusions: A well-defined clinically-based triage system produced meaningful reductions in imaging, opioid use, treatment duration, unplanned interventions, surgery and cost of care.

Grafting Polymer Brushes by ATRP from Functionalized Poly(ether ether ketone) Microparticles.

Poly(ether ether ketone) (PEEK) is a semi-crystalline thermoplastic with excellent mechanical and chemical properties. PEEK exhibits a high degree of resistance to thermal, chemical, and bio-degradation. PEEK is used as biomaterial in the field of orthopaedic and dental implants; however, due to its intrinsic hydrophobicity and inert surface, PEEK does not effectively support bone growth. Therefore, new methods to modify PEEK's surface to improve osseointegration are key to next generation polymer implant materials. Unfortunately, PEEK is a challenging material to both modify and subsequently characterize thus stymieing efforts to improve PEEK osseointegration. In this manuscript, we demonstrate how surface-initiated atom transfer radical polymerization (SI-ATRP) can be used to modify novel PEEK microparticles (PMP). The hard core-soft shell microparticles were synthesized and characterized by DLS, ATR-IR, XPS and TEM, indicating the grafted materials increased solubility and stability in a range of solvents. The discovered surface grafted PMP can be used as compatibilizers for the polymer-tissue interface.

A Deep Learning Model for Automated Classification of Intraoperative Continuous EMG.

OBJECTIVE: Intraoperative neurophysiological monitoring (IONM) is the use of electrophysiological methods during certain high-risk surgeries to assess the functional integrity of nerves in real time and alert the surgeon to prevent damage. However, the efficiency of IONM in current practice is limited by latency of verbal communications, inter-rater variability, and the subjective manner in which electrophysiological signals are described. METHODS: In an attempt to address these shortcomings, we investigate automated classification of free-running electromyogram (EMG) waveforms during IONM. We propose a hybrid model with a convolutional neural network (CNN) component and a long short-term memory (LSTM) component to better capture complicated EMG patterns under conditions of both electrical noise and movement artifacts. Moreover, a preprocessing pipeline based on data normalization is used to handle classification of data from multiple subjects. To investigate model robustness, we also analyze models under different methods for processing of artifacts. RESULTS: Compared with several benchmark modeling methods, CNN-LSTM performs best in classification, achieving accuracy of 89.54% and sensitivity of 94.23% in cross-patient evaluation. CONCLUSION: The CNN-LSTM model shows promise for automated classification of continuous EMG in IONM. SIGNIFICANCE: This technique has potential to improve surgical safety by reducing cognitive load and inter-rater variability.

Development of a model based method for investigating facet articulation.

Reported investigations of facet articulation in the human spine have often been conducted through the insertion of pressure sensitive film into the joint space, which requires incision of the facet capsule and may alter the characteristics of interaction between the facet surfaces. Load transmission through the facet has also been measured using strain gauges bonded to the articular processes. While this method allows for preservation of the facet capsule, it requires extensive instrumentation of the spine, as well as strain-gauge calibration, and is highly sensitive to placement and location of the strain gauges. The inherently invasive nature of these techniques makes it difficult to translate them into medical practice. A method has been developed to investigate facet articulation through the application of test kinematics to a specimen-specific rigid-body model of each vertebra within a lumbar spine segment. Rigid-body models of each vertebral body were developed from CT scans of each specimen. The distances between nearest-neighboring points on each facet surface were calculated for specific time frames of each specimen's flexion/extension test. A metric describing the proportion of each facet surface within a distance (2 mm) from the neighboring surface, the contact area ratio (CAR), was calculated at each of these time frames. A statistically significant difference (p<0.037) was found in the CAR between the time frames corresponding to full flexion and full extension in every level of the lumbar spine (L1-L5) using the data obtained from the seven specimens evaluated in this study. The finding that the contact area of the facet is greater in extension than flexion corresponds to other findings in the literature, as well as the generally accepted role of the facets in extension. Thus, a biomechanical method with a sufficiently sensitive metric is presented as a means to evaluate differences in facet articulation between intact and treated or between healthy and pathologic spines.

Stimulation of the globus pallidus internus in a patient with DYT1-positive primary generalized dystonia: a 10-year follow-up.

The authors report the case of DYT1-positive primary generalized dystonia refractory to medical management that was successfully treated with continuous deep brain stimulation of the internal segment of the globus pallidus. Prior studies have shown that neuromusculoskeletal deficits can remain permanent if early surgical intervention is not undertaken. The authors report prolonged efficacy and safety over a 10-year period in a 28-year-old man.

Current Concepts of Contemporary Expandable Lumbar Interbody Fusion Cage Designs, Part 2: Feasibility Assessment of an Endplate Conforming Bidirectional Expandable Interbody Cage.

BACKGROUND: Expandable cages that allow for bidirectional expansion, in both height and width, may offer benefits over traditional expandable cages or static cages. Effective stiffness must also be considered, as implants with exceedingly high stiffness may increase subsidence risk and reduce graft loading. METHODS: A retrospective case series of 7 patients were assessed with computed tomography (CT) scan at the final 1-year follow-up to evaluate the interbody fusion and configuration of the expandable cage related to the endplates within the intervertebral space. CT scans were reformatted using cage's tantalum markers as fiducials for single-plane orientation for each intervertebral cage. Device height and width at maximum in situ expansion was measured at its anterior and posterior aspects to evaluate implant deformation. The new bone volume within each cage was measured from the same CT scan data sets and by the Bridwell classification of interbody fusion. RESULTS: The average difference between medial and lateral height measurements was 1.82 mm (±1.08) at the device's anterior aspect and 1.41 mm (±0.98) at the posterior aspect. The average difference between medial and lateral heights was 18.55% (±9.34) anteriorly and 15.49% (±9.24) posteriorly. There was a successful fusion in all 7 patients, as evidenced by measurable bone volume in the center of each interbody cage with an average of 586.42 mm3 (±237.06). CONCLUSION: The authors demonstrated the feasibility of successfully using bidirectionally expandable multimaterial cages to achieve interbody fusion. These composite open-architecture cages were found to conform to each patient's endplate configuration. The authors' observations support the concept of material selection impacting the effective construct stiffness. The design investigated by the authors provided sufficient anterior column support and successful fusion in all patients. LEVEL OF EVIDENCE: 4.

A comparative study of three biomaterials in an ovine bone defect model.

BACKGROUND: Polyetheretherketone (PEEK), and more recently titanium-coated PEEK, have been given serious consideration as biomaterial design choices for spinal interbody implants. Shortcomings in these materials necessitate further innovation into materials research, for example, on PEKK. Common complications such as surface delamination (as with titanium coating) and lack of bone apposition (as with PEEK) indicate the need for a new material that inherently displays preferable bone growth characteristics without sacrificing structural integrity. PURPOSE: To compare three biomaterials with respect to their osseointegrative capacity. STUDY DESIGN: Evaluate the in vivo material characteristics of three separate biomaterials in an ovine bone defect model: PEEK, titanium-coated PEEK (Ti-coated PEEK), and 3D-printed PEKK. Biomechanical, histologic, and radiographic testing was the basis for evaluation and material characterization. METHODS: Eight ovine specimens were implanted with one of each of the three types of biomaterials tested in both left and right epicondyles using a femoral bone defect model, and were sacrificed at 8 and 16 weeks. Implants were then analyzed using a push-out method, histologic staining, and various radiographic tests. Industry funding was provided for the completion of this research study, followed by an independent third party review of all relevant data for publication. RESULTS: PEKK implants demonstrated bone ingrowth, no radiographic interference, no fibrotic tissue membrane formation, significant increase in bony apposition over time, and significantly higher push-out strength compared to standard PEEK. The PEKK implant displayed bone growth characteristics comparable to Ti-coated PEEK with significant improvements in implant integrity and radiographic properties. CONCLUSION: This study found that PEKK displayed preferable characteristics when compared to PEEK and Ti-coated PEEK, and is therefore a potential alternative to their use.

Current Concepts of Contemporary Expandable Lumbar Interbody Fusion Cage Designs, Part 1: An Editorial on Their Biomechanical Characteristics.

BACKGROUND: Bidirectional expandable designs for lumbar interbody fusion cages are the latest iteration of expandable spacers employed to address some of the common problems inherent to static interbody fusion cages. OBJECTIVE: To describe the rationales for contemporary bidirectional, multimaterial expandable lumbar interbody fusion cage designs to achieve in situ expansion for maximum anterior column support while decreasing insertion size during minimal-access surgeries. METHODS: The authors summarize the current concepts behind expandable spinal fusion open architecture cage designs focusing on advanced minimally invasive spinal surgery techniques, such as endoscopy. A cage capable of bidirectional expansion in both height and width to address constrained surgical access problems was of particular interest to the authors while they analyzed the relationship between implant material stiffness and geometric design regarding the risk of subsidence and reduced graft loading. CONCLUSIONS: Biomechanical advantages of new bidirectional, multimaterial expandable interbody fusion cages allow insertion through minimal surgical access and combine the advantages of proven device configurations and advanced material selection. The final construct stiffness is sufficient to provide immediate anterior column support while accommodating reduced sizes required for minimally invasive surgery applications. LEVEL OF EVIDENCE: 7.

Prevention of Implant-Associated Infection in Neuromodulation: Review of the Literature and Prototype of a Novel Protective Implant Coating.

Background: Implanting hardware into surgical sites increases the rate of infection associated with these sites. Without novel efforts to reduce this rate of infection, we can expect to see an increase in the number of hardware-associated infections as more patients are implanted with these devices. These infections often necessitate the removal of these devices resulting in a significant financial and clinical burden to patients. We developed a prototype antibiotic coating using products that are both low cost and that can be sourced easily. Our study aims to test the effectiveness of this coating against bacteria commonly observed in hospital-associated infections. Methods: The antibiotic coating was prepared by combining one gram of vancomycin and 500 mg of ciprofloxacin in 50 mL of glycerol. The coating was examined for inhibition of growth of Pseudomonas aeruginosa PA14 and Staphylococcus aureus AH2486 and compared with the bacterial growth of the above bacteria in glycerol alone. The growth curves were plotted measuring the bacterial growth at 5 h intervals. Results: The results of the growth curves clearly demonstrate a lack of bacterial growth when these bacteria are combined with glycerol combined with our selected antibiotic agents. Conclusion: There appears to be a limited interest from device companies in developing new strategies for infection prevention associated with neurosurgical hardware, and we propose that this prototype will be an effective and low-cost solution to a large problem.

Bidirectional Expandable Technology for Transforaminal or Posterior Lumbar Interbody Fusion: A Retrospective Analysis of Safety and Performance.

BACKGROUND: Expandable devices for transforaminal or posterior lumbar interbody fusion (TLIF and PLIF, respectively) may enable greater restoration of disc height, foraminal height, and stability within the interbody space than static spacers. Medial-lateral expansion may also increase stability and resistance to subsidence. This study evaluates the clinical and radiographic outcomes from early experience with a bidirectional expandable device. METHODS: This was a retrospective analysis of a continuous series of patients across 3 sites who had previously undergone TLIF or PLIF surgery with a bidirectional expandable interbody fusion device (FlareHawk, Integrity Implants, Inc) at 1 or 2 contiguous levels between L2 and S1. Outcomes included the Oswestry Disability Index (ODI), a visual analog scale (VAS) for back pain or leg pain, radiographic fusion by 1 year of follow-up, subsidence, device migration, and adverse events (AE). RESULTS: There were 58 eligible patients with radiographs for 1-year fusion assessments and 45 patients with ODI, VAS back pain, or VAS leg pain data at baseline and a mean follow-up of 4.5 months. The ODI, VAS back pain, and VAS leg pain scores improved significantly from baseline to final follow-up, with mean improvements of 14.6 ± 19.1, 3.4 ± 2.6, and 3.9 ± 3.4 points (P < .001 for each), respectively. In addition, 58% of patients achieved clinically significant improvements in ODI, 76% in VAS back pain, and 71% in VAS leg pain. By 1 year, 96.6% of patients and 97.4% of levels were considered fused. There were zero cases of device subsidence and 1 case of device migration (1.7%). There were zero device-related AEs, 1 intraoperative dural tear, and 3 subsequent surgical interventions. CONCLUSIONS: The fusion rate, improvements in patient-reported outcomes, and the AEs observed are consistent with those of other devices. The bidirectional expansion mechanism may provide other important clinical value, but further studies will be required to elucidate the unique advantages. LEVEL OF EVIDENCE: 4.

Effect of fibrin glue on the prevention of persistent cerebral spinal fluid leakage after incidental durotomy during lumbar spinal surgery.

Approximately one million spinal surgeries are performed in the United States each year. The risk of an incidental durotomy (ID) and resultant persistent cerebrospinal fluid (CSF) leakage is a significant concern for surgeons, as this complication has been associated with increased length of hospitalization, worse neurological outcome, and the development of CSF fistulae. Augmentation of standard dural suture repair with the application of fibrin glue has been suggested to reduce the frequency of these complications. This study examined unintended durotomies during lumbar spine surgery in a large surgical patient cohort and the impact of fibrin glue usage as part of the ID repair on the incidence of persistent CSF leakage. A retrospective analysis of 4,835 surgical procedures of the lumbar spine from a single institution over a 10-year period was performed to determine the rate of ID. The 90-day clinical course of these patients was evaluated. Clinical examination, B-2 transferrin assay, and radiographic imaging were utilized to determine the number of persistent CSF leaks after repair with or without fibrin glue. Five hundred forty-seven patients (11.3%) experienced a durotomy during surgery. Of this cohort, fibrin glue was used in the dural repair in 278 patients (50.8%). Logistic models evaluating age, sex, redo surgery, and the use of fibrin glue revealed that prior lumbar spinal surgery was the only univariate predictor of persistent CSF leak, conferring a 2.8-fold increase in risk. A persistent CSF leak, defined as continued drainage of CSF from the operative incision within 90 days of the surgery that required an intervention greater than simple bed rest or over-sewing of the wound, was noted in a total of 64 patients (11.7%). This persistent CSF leak rate was significantly higher (P < 0.001) in patients with prior lumbar surgery (21%) versus those undergoing their first spine surgery (9%). There was no statistical difference in persistent CSF leak between those cases in which fibrin glue was used at the time of surgery and those in which fibrin glue was not used. There were no complications associated with the use of fibrin glue. A history of prior surgery significantly increases the incidence of durotomy during elective lumbar spine surgery. In patients who experienced a durotomy during lumbar spine surgery, the use of fibrin glue for dural repair did not significantly decrease the incidence of a persistent CSF leak.

Load sharing and stabilization effects of anterior cervical devices.

STUDY DESIGN: Biomechanical human cadaveric cervical flexibility testing with direct load-sharing measurement. OBJECTIVE: To determine if the flexibility and load-sharing characteristics of a functional spinal unit were affected by anterior treatments for cervical pathologies. SUMMARY OF BACKGROUND DATA: With advancements in polymers, anterior cervical plates have used thermoplastics including recent designs from biodegradable polylactide acids. However, the difference in material properties between metal and polymer can be significant. METHODS: Thirteen cervical spine specimens were subjected to 5 treatments at C4-C5. Each treatment for each specimen was subjected to multidirectional flexibility testing. The third cycle was used for treatment comparisons. RESULTS: With the integrated load cell spacer, the mean range of motion for the functional spinal unit measured on average 104% + or - 40% normalized to the intact control. The mean biodegradable and titanium plate were 55% + or - 31% and 40% + or - 36%, respectively. Both plates exhibited statistically lower mean range of motions (P = 0.001 and P < 0.001) compared with spacers. The load transmitted through the interbody space was 54% + or - 20%, 43% + or - 20%, and 33% + or - 15% on average for the spacer, biodegradable, and titanium plate constructs, respectively. No statistically significant difference was detected between the biodegradable plate and spacer (P = 0.214). CONCLUSIONS: From this research, a biodegradable plate offers immediate postoperative stability significantly different than spacer alone treatments but with graft load sharing that is statistically no different. Thus, the intrinsic lower native material modulus of elasticity of biodegradable polymers has biomechanical implications. However, clinical evidence, particularly for long-term outcomes, will be required in understanding the efficacy of biodegradable polymers.