A Novel Trajectory of C7 Laminar Screws Determined Using Three-Dimensional Computed Tomography and Surgical Simulation Software: Comparison with a Pre-existing Trajectory.

STUDY DESIGN: Examination using three-dimensional screw trajectory software and computed tomographic scans. PURPOSE: To evaluate the feasibility of a novel trajectory for C7 laminar screws and to compare it with an old trajectory. OVERVIEW OF LITERATURE: The previously reported trajectory of C7 laminar screws has a horizontal direction without a fixed target point. Our new trajectory has a cephalad direction with a fixed target point. METHODS: Computed tomographic scans of a total of 50 male and 50 female patients were utilized. The placement of C7 laminar screws was activated employing the new and old trajectories. The success rate, the causes of failure, and the maximum allowable length of each trajectory were compared. RESULTS: Employing the new trajectory, the success rates of the unilaminar and bilaminar screws were 93% and 83%, respectively, which were significantly better than the old trajectory (80%, p<0.0001 and 70%, p=0.0003). The most prevalent cause of failure was laminar cortical breach followed by facet joint violation. The new trajectory also offered significantly longer maximum allowable screw length in unilaminar (32.5±4.3 mm vs. 26.5±2.6 mm, p<0.001), bilaminar cephalic (29.5±3.8 mm vs. 25.9±2.6 mm, p<0.0001) and bilaminar caudal (33.1±2.6 mm vs. 25.8±3.1 mm, p<0.001) screws than the old trajectory. With the new and old trajectories, 70% vs. 6% of unilaminar, 60% vs. 2% of bilaminar caudal, and 32% vs. 4% of bilaminar cephalic screws could be protracted perfectly into the corresponding lateral mass without any laminar cortical or facet joint violation (p<0.0001). CONCLUSIONS: The novel trajectory possesses a substantially higher success rate, longer maximum allowable screw length, and higher chance to be extended into the lateral mass (a condition known as a lamino-lateral mass screw) than the old trajectory.

Research Models of the Nanoparticle-Mediated Drug Delivery across the Blood-Brain Barrier.

Brain diseases and damages come in many forms such as neurodegenerative diseases, tumors, and stroke. Millions of people currently suffer from neurological diseases worldwide. While Challenges of current diagnosis and treatment for neurological diseases are the drug delivery to the central nervous system. The Blood-Brain Barrier (BBB) limits the drug from reaching the targeted site thus showing poor effects. Nanoparticles that have advantage of the assembly at the nanoscale of available biomaterials can provide a delivery platform with potential to raising brain levels of either imaging therapeutic drugs or imaging. Therefore, successful modeling of the BBB is another crucial factor for the development of nanodrugs. In this review, we analyze the in vitro and in vivo findings achieved in various models, and outlook future development of nanodrugs for the successful treatment of brain diseases and damages.

Biomechanical analysis of lumbar decompression surgery in relation to degenerative changes in the lumbar spine - Validated finite element analysis.

BACKGROUND: There are no studies about the biomechanical analysis of lumbar decompression surgery in relation to degenerative changes of the lumbar spine. Therefore, the purpose of this study was to compare, by using finite element (FE) analysis, the biomechanical changes of the lumbar spine in terms of annulus stress and nucleus pressure after two different kinds of lumbar decompression surgery in relation to disc degenerative changes. METHODS: The validated intact and degenerated FE models (L2-5) were used in this study. In these two models, two different decompression surgical scenarios at L3-4, including conventional laminectomy (ConLa) and the spinous process osteotomy (SpinO), were simulated. Therefore, a total of six models were simulated. Under preloading, 7.5 Nm moments of flexion, extension, lateral bending, and torsion were imposed. In each model, the maximal von Mises stress on the annulus fibrosus and nucleus pressure at the index segment (L3-4) and adjacent segments (L2-3 and L4-5) were analyzed. RESULTS: The ConLa model and disc degeneration model demonstrated a larger annulus stress at the decompression level (L3-4) under all four moments than were seen in the SpinO model and healthy disc model, respectively. Therefore, the ConLa model with moderate disc degeneration showed the highest annulus stress at the decompression level (L3-4). However, the percent change of annulus stress at L3-4 from the intact model to the matched decompression model was less in the moderate disc degeneration model than in the healthy disc model. CONCLUSIONS: Although the ConLa model with moderate disc degeneration showed the highest annulus stress, the degenerative models would be less influenced by the decompression technique.

Efficacy of a Topical Gelatin-Thrombin Matrix Sealant in Reducing Postoperative Drainage Following Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective fusion level(s)-, age-, and gender-matched analysis. PURPOSE: To determine whether the application of a topical gelatin-thrombin matrix sealant (Floseal) at the end of anterior cervical discectomy and fusion (ACDF) can reduce the amount of postoperative hemorrhage. OVERVIEW OF LITERATURE: The effect of the matrix sealant in decreasing postoperative hemorrhage following ACDF has not been reported. METHODS: Matrix sealant was (n=116, study group) or was not applied (n=58, control group) at the end of ACDF. Patients were selected by 1:2 matching criteria of fusion level(s), age, and gender. Seven parameters described below were compared between the two groups. RESULTS: The total drain amount for the first 24 hours (8±9 versus 27±22 mL), total drain amount until the 8-hour drainage decreased to ≤10 mL (8±10 versus 33±26 mL), and the total drain amount until 6 AM on the first postoperative day (7±8 versus 24±20 mL) were significantly lower in the study group than the control group (all p<0.001). The time for the 8-hour drainage to decrease to ≤10 mL was significantly lower in the study group (10±5 versus 26±14 hours, p<0.001). The 8-hour drainage decreased to ≤10 mL on the operation day in most patients (88%) in the study group versus mostly on the first (48%) or second (33%) postoperative day in the control group (p<0.001). The total drain amount until 6 AM on the first postoperative day was 0 mL in 43% of patients in the study group and in 7% in the control group (p<0.001). No patient in either group required hematoma evacuation. CONCLUSIONS: Application of the topical matrix sealant at the end of ACDF can significantly reduce the amount of postoperative hemorrhage.