Effect Of Insertion Angle Research Articles

Effect of Screw Insertion Torque on Mechanical Properties of a Hybrid Polyaxial Locking System.

The aim of this study was to determine the effect of insertion torque and angulation on the push-out strength of screws in Atraumatic Rigid Fixation (ARIX) system. In vitro mechanical tests of the ARIX system were conducted. Screw plate constructs (n = 120) were tested using five different insertion torques at four different angles relative to the perpendicular axis of the plate. Before the push-out test, screws were locked into the plates, and the push-out force of the screw was measured by applying a load parallel to the screw axis. Implant failure was observed at 0.8 Nm at an insertion angle of 15 degrees, and at 1 Nm at 0 degree, 5 degrees and 10 degrees. Two types of failures were observed: cold welding and plate deformation. An insertion torque of 0.8 Nm produced a significantly higher push-out force compared with 0.2 Nm. Non-angled specimens with 0.8 Nm insertion torque exhibited significantly higher screw push-out forces compared with other tested specimens and insertion angles. Insertion angle did not affect screw push-out force at insertion torques of 0, 0.2, 0.4 and 0.6 Nm. The ARIX locking system is much more sensitive to insertion torque than angle. An effect of insertion angle was observed only at an insertion torque of 0.8 Nm, under which all angles significantly decreased push-out force relative to zero degrees of angulation. In addition, low insertion torques can result in screws loosening over time, while greater insertion torques than 1 Nm can result in screw head stripping and plate hole deformation.

The Effect of Insertion Angle on Primary Stability of Orthodontic Mini-implants "An Experimental in vivo Study"

The Effect of Insertion Angle on Primary Stability of Orthodontic Mini-implants "An Experimental in vivo Study"

Effect of insertion angle on the stability of orthodontic mini-implants in a rabbit tibia model: A finite element analysis.

Mini-implants are an alternative to traditional methods of anchorage in orthodontic treatment. However, there are still questions concerning their application, in particular, with the insertion angle. To determine whether the angle of insertion of the mini-implant is a determining factor in their primary stability when they support orthodontic loads. A finite element model (FEM) of tibia bone, spring and mini-implant was developed. The three-dimensional model of the rabbit tibia was constructed based on tomographic slices. The angles that were analyzed were 90°, 80°, 70°, 60°, 50°, 45°, 40°, and 30°. A horizontal force of 2 N applied to the head of the mini-implants was simulated. The von Mises stresses and displacements were determined using FEM. Von Mises stresses were lower for an insertion angle of 40° followed by 90° and 70°; likewise, the displacements of the mini-implants with respect to the spring were lower for the 40° angle followed by 90° and 70°, we found a statistically significant association between the insertion angle and displacement. All mini-implants underwent a degree of angulation and displacement; however, mini-implants inserted to the bone surface at 40° tend to have better primary stability, and they can withstand loads immediately.

The effect of insertion angle and pulling angle on the pullout strength of all-suture type anchors

The effect of insertion angle and pulling angle on the pullout strength of all-suture type anchors

Effect of Insertion Angle on Locking Mechanism Strength in Polyaxial Plates

Distal elbow fractures tend to involve poor bone quality and are intra-articular, compromising stability. Locking plate and screw constructs have higher pull-out strength which is instrumental in repairing osteoporotic bone or comminuted fractures; however, the screw insertion angle is fixed relative to the plate. To address the limitation of monoaxial locking plates, polyaxial plates have allowed surgeons greater freedom in screw angulation to accommodate complex fractures. The objective of this study was to evaluate the effect of screw angle insertion on the screw-plate fixation strength of polyaxial locking plates. We hypothesized the angle of insertion of the locking screw is inversely proportional to the fixation strength of the locking mechanism.

The mechanisms of medial pedicle wall violation: insertion method is as important as correct cannulation of the pedicle.

A cadaver study aims to determine the mechanisms of medial pedicle wall violation after a correct cannulation of the pedicle. The study presents finding out the effect of insertion angle and insertion force on medial wall violation. We used 100 lumbar pedicles of cadavers. Special wooden blocks were produced to simulate a fixed angle fault after a correct pedicle cannulation. Pedicles were divided into 4 groups: 10-degree free drive (group 10), 15-degree free drive (group 15), 10-degree push drive (group 10P), and 15-degree push drive (group 15P). After insertion of pedicle screws, laminectomies were done and the pedicles were evaluated from the inside. Pedicle complications were more in group 10P than group 10 (P = 0.009). Medial wall fracture (P = 0.002) and canal penetration were more in group 15P than group 15 (P = 0.001). Groups 10P and 15P were similar regarding medial wall fractures but canal penetration was significantly higher in group 15P (P = 0.001). Medial wall breaches can happen after correct cannulation of pedicles. Change in insertion angle is one factor but the most important factor is the use of a pushing force while inserting a screw. The pedicle seems to be extremely tolerant to insertion angulation mistakes up to 10 degrees and tends to lead the screw into the correct path spontaneously.

In Vitro Tests for Aerosol Deposition. III: Effect of Inhaler Insertion Angle on Aerosol Deposition

Inhaler orientation with respect to a patient's mouth may be an important variable determining the efficiency of aerosol lung delivery. The effect of insertion angle on regional deposition was evaluated for a series of inhalers using concurrent in vitro and computational fluid dynamics (CFD) analysis. Geometrically realistic physical mouth-throat (MT) and upper tracheobronchial (TB) models were constructed to connect different inhalers at a series of insertion angles relative to the horizontal plane of the model. These models were used to assess albuterol sulfate deposition from the Novolizer(®) dry powder inhaler (DPI), Proventil(®) HFA pressurized metered dose inhaler (MDI), and Respimat(®) Soft Mist™ Inhaler (SMI) following the actuation of a single dose. Drug deposition from Novolizer DPI was studied for Salbulin(®) and an experimental "drug only" formulation. Albuterol sulfate was recovered and quantified from the device and the MT and TB regions. Significant differences in MT and total lung dose (TLD) of albuterol sulfate deposition were not observed for Salbulin Novolizer DPI and Respimat SMI inserted at different angles. In contrast, drug-only Novolizer DPI and Proventil HFA MDI showed a significant difference in MT and TLD deposition using different insertion angles. For drug-only Novolizer DPI and Proventil HFA MDI, the lowest and the highest MT depositions were observed at +10° and -20°, respectively; for Respimat SMI and Salbulin Novolizer DPI, these angles were -10° and +10°, and +20° and -20°, respectively. CFD simulations were in agreement with the experimental results and illustrated shifts in local particle deposition associated with changes in insertion angle. The effect of inhaler orientation at the inhaler-mouth interface on MT aerosol deposition appeared to be dependent on velocity, aerosol size, and formulation. These findings not only demonstrate the need for patient education on correct inhaler orientation, but provide important new methods for those designing new inhalers.