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.

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.

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.

Co-mapping 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 co-mapping local data from vascular wall biology with local hemodynamic data. In this study, we developed an imaging pipeline to address this pressing need. A protocol that employs scanning multiphoton microscopy was designed to obtain 3D data sets for smooth muscle actin, collagen and elastin in intact vascular specimens. A cluster analysis was developed to objectively categorize the smooth muscle cells (SMC) across the vascular specimen based on SMC density. In the final step in this pipeline, the location specific categorization of SMC, along with wall thickness was co-mapped with patient specific hemodynamic results, enabling direct quantitative comparison of local flow and wall biology in 3D intact specimens.

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.

The Presence of Biofilms in Instrumented Spinal Fusions.

Study Design: Prospective observational cohort study. Objective: To determine whether biofilms exist on spinal instrumentation recovered during revision surgery in which microbial cultures were negative. Background: Biofilm bacteria are extremely difficult to detect by conventional culture methods used in the standard hospital setting. Chronic infections in which bacteria form biofilms have been demonstrated to slow healing and prevent bony fusion. These slime encased microbial communities serve to isolate the bacteria from the body's immune responses, while simultaneously providing metabolic resistance to antimicrobial therapy. Methods: Traditional debridement wound cultures were taken from each specimen and sent for microbiological analyses. Bacterial DNA testing was performed using polymerase chain reaction (PCR) electrospray ionization-mass spectrometry (ESI-MS). Based on the PCR/ESI-MS results, specific crossed immune electrophoresis was used to detect the bacterial species within biofilms observed on the removed instrumentation. In addition, fluorescent in situ hybridization (FISH) probes corresponding to the bacterial species identified by PCR/ESI-MS were used with confocal microscopy to visualize and confirm the infecting bacteria. Results: Fifteen patients presented for surgical revision of thoracolumbar spinal implantation: four for clinical suspicion of infection, six for adjacent segment disease (ASD), one with ASD and pseudoarthrosis (PA), three with PA, and one for pain. Infections were confirmed with PCR/ESI-MS for all four patients who presented with clinical infection, and for five of the patients for whom infection was not clinically suspected. Of the presumed non-infected implants, 50% demonstrated the presence of infectious biofilms. Half of the revisions due to pseudoarthrosis were shown to harbour biofilms. The revisions that were performed for pain demonstrated robust biofilms but did not grow bacteria on traditional culture media. Conclusions: Culture is inadequate as a diagnostic modality to detect indolent/subclinical biofilm infections of spinal instrumentation. The PCR/ESI-MS results for bacterial detection were confirmed using species-specific microscopic techniques for both bacterial nucleic acids and antigens. Biofilms may contribute to pseudoarthrosis and back pain in postoperative wounds otherwise considered sterile.

Biomechanical Characterization of Unilateral and Bilateral Posterior Lumbar Interbody Fusion Constructs.

Objectives: To compare the biomechanical stability of two-level PLIF constructs with unilateral and bilateral pedicle screw fixations. Methods: Six cadaveric lumbar segments were evaluated to assess biomechanical stability in response to pure moment loads applied in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Each specimen was tested in six sequential configurations: (1) intact baseline; (2) facetectomy; (3) unilateral pedicle screws (UPS); (4) bilateral pedicle screws (BPS); (5) unilateral pedicle screws and cage (UPSC); and (6) bilateral pedicle screws and cage (BPSC). Results: Significant reductions in motion were observed when comparing all instrumented conditions to the intact and facetectomy stages of testing. No significant differences in motion between UPS, BPS, UPSC, or BPSC were observed in response to FE range of motion (ROM) or neutral zone (NZ). ROM was significantly higher in the UPS stage compared to BPS in response to LB and AT loading. ROM was significantly higher in UPSC compared to BPSC in response to LB loading only. Similarly, NZ was significantly higher in UPSC compared to BPSC in response to only LB loading. In response to AT loading, ROM was significantly higher during UPS than BPS or BPSC; however, no significant differences were noted between UPSC and BPSC with respect to AT ROM or NZ. Conclusion: BPS fixation is biomechanically superior to UPS fixation in multilevel PLIF constructs. This was most pronounced during both LB loading. Interbody support did contribute significantly to immediate stability.

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.

Prediction of bleb formation in intracranial aneurysms using machine learning models based on aneurysm hemodynamics, geometry, location, and patient population.

BACKGROUND: Bleb presence in intracranial aneurysms (IAs) is a known indication of instability and vulnerability. OBJECTIVE: To develop and evaluate predictive models of bleb development in IAs based on hemodynamics, geometry, anatomical location, and patient population. METHODS: Cross-sectional data (one time point) of 2395 IAs were used for training bleb formation models using machine learning (random forest, support vector machine, logistic regression, k-nearest neighbor, and bagging). Aneurysm hemodynamics and geometry were characterized using image-based computational fluid dynamics. A separate dataset with 266 aneurysms was used for model evaluation. Model performance was quantified by the area under the receiving operating characteristic curve (AUC), true positive rate (TPR), false positive rate (FPR), precision, and balanced accuracy. RESULTS: The final model retained 18 variables, including hemodynamic, geometrical, location, multiplicity, and morphology parameters, and patient population. Generally, strong and concentrated inflow jets, high speed, complex and unstable flow patterns, and concentrated, oscillatory, and heterogeneous wall shear stress patterns together with larger, more elongated, and more distorted shapes were associated with bleb formation. The best performance on the validation set was achieved by the random forest model (AUC=0.82, TPR=91%, FPR=36%, misclassification error=27%). CONCLUSIONS: Based on the premise that aneurysm characteristics prior to bleb formation resemble those derived from vascular reconstructions with their blebs virtually removed, machine learning models can identify aneurysms prone to bleb development with good accuracy. Pending further validation with longitudinal data, these models may prove valuable for assessing the propensity of IAs to progress to vulnerable states and potentially rupturing.

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.

Development and Characterization of Novel Conductive Sensing Fibers for In Vivo Nerve Stimulation.

Advancements in electrode technologies to both stimulate and record the central nervous system's electrical activities are enabling significant improvements in both the understanding and treatment of different neurological diseases. However, the current neural recording and stimulating electrodes are metallic, requiring invasive and damaging methods to interface with neural tissue. These electrodes may also degrade, resulting in additional invasive procedures. Furthermore, metal electrodes may cause nerve damage due to their inherent rigidity. This paper demonstrates that novel electrically conductive organic fibers (ECFs) can be used for direct nerve stimulation. The ECFs were prepared using a standard polyester material as the structural base, with a carbon nanotube ink applied to the surface as the electrical conductor. We report on three experiments: the first one to characterize the conductive properties of the ECFs; the second one to investigate the fiber cytotoxic properties in vitro; and the third one to demonstrate the utility of the ECF for direct nerve stimulation in an in vivo rodent model.

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.

Gender differences in degenerative lumbar scoliosis spine flexibilities.

OBJECTIVES: The incidence of adolescent idiopathic scoliosis is higher in girls, but spine deformities are more severe in boys. We aimed to identify gender differences of mechanical factors involved in adult degenerative scoliosis (DS). METHODS: 20 male (60.35±6.77 years) and 19 female (58.89±9.15 years) specimens of cadaveric lumbar spines were divided into 3 groups comprised of a Cobb angle >10° (DS), a Cobb angle <10° but >3° (pre-degenerative scoliosis (PS)) and intervertebral disc angles <3° in which the Cobb angle could not be measured (non-degenerative scoliosis (NS)), respectively. Spine data were collected for flexion/extension (FE), lateral bending (LB), axial torsion (AT), range of motion (ROM), neutral zone (NZ) and the neutral zone ratio (NZR). RESULTS: There was no significant difference regarding the severity of DS between male and female specimens. Only in males were ROMAT (P=0.001), NZAT (P<0.001), NZFE (P=0.045), NZLB (P=0.002) as well as NZRAT (P<0.001) and NZRLB (P=0.001) values significantly lower in right compared to left scoliosis. With the exception of ROMAT in DS specimens, ROMAT, ROMFE and ROMLB values were significantly higher in females than those in males for the DS, PS and NS specimens. NZAT, NZFE and NZLB values were significantly higher in PS and NS female specimens. NZRAT was significantly lower in female DS specimens (P=0.031) and significantly higher in female PS specimens (P=0.031) compared to that in male specimens. CONCLUSIONS: In lumbar scoliosis specimens, the rigidness of spines was higher in males than in females and more pronounced in right than in left scoliosis, but only in males.

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.

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.

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.

Expandable Interbody Fusion Cages: An Editorial on the Surgeon's Perspective on Recent Technological Advances and Their Biomechanical Implications.

BACKGROUND: Expandable cages have gone through several iterations since they first appeared on the market in the early 2000s. Their development was prompted by some common problems associated with static interbody cages, including migration, expulsion, dural or neural traction injury, and pseudarthrosis. OBJECTIVE: To summarize current technological advances from earlier expandable lumbar interbody fusion devices to implants with vertical and medial-to-lateral expansion mechanisms. METHODS: The authors review the currently available expandable cage designs, the incremental technological advances, and how these devices impact minimally invasive surgery interbody procedures and clinical outcomes. The strategic concepts intended to improve the minimally invasive application of expandable interbody fusion implants are reviewed from a surgeon's perspective in a clinical context to discuss how their use may improve patient outcomes. CONCLUSIONS: The geometrical configuration, effective stiffness of composite multi-material cage designs may impact the bone-implant contact area with the endplates. Hybridization strategies of expandable cage technology with modern minimally invasive and endoscopic spinal surgery techniques are presented by outlining their advantages and disadvantages. LEVEL OF EVIDENCE: 1 CLINICAL RELEVANCE: Systematic review.

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.

Comparative analysis of the lateral and posterolateral trajectories for fixation of the sacroiliac joint-a cadaveric study.

BACKGROUND: A number of minimally invasive sacroiliac (SI) joint fusion solutions for placing implants exist, with reduced post-operative pain and improved outcomes compared to open procedures. The objective of this study was to compare two MIS SI joint fusion approaches that place implants directly across the joint by comparing the ilium and sacrum bone characteristics and SI joint separation along the implant trajectories. METHODS: Nine cadaveric specimens (n = 9) were CT scanned and the left and right ilium and sacrum were segmented. The bone density, bone volume fraction, and SI joint gap distance were calculated along lateral and posterolateral trajectories and compared using analysis of variance between the two orientations. RESULTS: Iliac bone density, indicated by the mean Hounsfield Unit, was significantly greater for each lateral trajectory compared to posterolateral. The volume of cortical bone in the ilium was greater for the middle lateral trajectory compared to all others and for the top and bottom lateral trajectories compared to both posterolateral trajectories. Cortical density was greater in the ilium for all lateral trajectories compared to posterolateral. The bone fraction was significantly greater in all lateral trajectories compared to posterolateral in the ilium. No differences in cortical volume, cortical density, or cancellous density were found between trajectories in the sacrum. The ilium was significantly greater in density compared with the sacrum when compared irrespective of trajectory (p < 0.001). The posterolateral trajectories had a significantly larger SI joint gap than the lateral trajectories (p < 0.001). CONCLUSION: Use of the lateral approach for minimally invasive SI fusion allows the implant to interact with bone across a significantly smaller joint space. This interaction with increased cortical bone volume and density may afford better fixation with a lower risk of pull-out or implant loosening when compared to the posterolateral approach.

Toward Next-Generation Biohybrid Catalyst Design: Influence of Degree of Polymerization on Enzyme Activity.

Due to their capacity to conduct complex organic transformations, enzymes find extensive use in medical and industrial settings. Unfortunately, enzymes are limited by their poor stability when exposed to harsh non-native conditions. While a host of methods have been developed to stabilize enzymes in non-native conditions, recent research into the synthesis of polymer-enzyme biohybrids using reversible deactivation radical polymerization approaches has demonstrated the potential of increased enzymatic activity in both native and non-native environments. In this manuscript, we utilize the enzyme lipase, as a model system, to explore the impact that modulation of grafted polymer molecular weight has on enzyme activity in both aqueous and organic media. We studied the properties of these hybrids using both solution-phase enzyme activity methods and coarse-grain modeling to assess the impact of polymer grafting density and grafted polymer molecular weight on enzyme activity to gain a deeper insight into this understudied property of the biohybrid system.