Biomedical engineering advances最新文献

A cerebral aneurysm is a medical disorder that occurs when the wall of the cerebral artery ruptures as a result of abnormally high blood pressure. The imaging techniques that are now in use, such as CT and MRI scans, can only show the geometrical information about an aneurysm and cannot determine the risk of rupture that relates to the progression of an aneurysm. In this work, computational modeling was performed to simulate aneurysm progression and to analyze the stress development for a variety of different pressure loading conditions. Image segmentation was utilized to segment one anterior cerebral artery and one anterior communicating artery, both of which were rebuilt to generate aneurysm models at susceptible locations of the aneurysm progression simulation. To represent the various phases of aneurysm development, five different aneurysm sizes with two varying wall thicknesses were identified. The diastolic pressure, the systolic pressure, and the hypertensive pressure were applied to simulate the actual pressure conditions for the anterior cerebral arteries. The rupture risk was determined by analyzing the stress distributions across all of the models. It was estimated that the stresses around the walls of aneurysm varies with an incremental change in both the diameter of the aneurysm and the magnitude of the blood pressure. Aneurysms that were observed to have significant rupture risks were those that had a large diameter and a thin wall and were simulated at high blood pressures. The findings of this research are anticipated to assist medical practitioners in estimating rupture risks with known imaging, based on the diameters of aneurysms, and in early decision making for the treatment of aneurysms.

Background context

Lumbar spine disc pathologies often necessitate removal of the intervertebral disc and implantation of a lumbar interbody fusion (LIF) device. Herein, the objective was to measure use condition forces while simulating intra-operative loading conditions of transforaminal lumbar interbody fusion (TLIF) procedures.

Methods

In this work, we developed a transferable method to measure impact forces in a cadaveric intra-operative setting and designed a drop weight benchtop device equipped with force and displacement sensors to replicate cadaveric impact conditions, including number of strikes required for interbody device insertion, peak force, initial slope of the impact waveform, impact duration, and area under the force-time curve (impulse). Following cadaveric testing, a benchtop biomechanical study varying interbody device height, drop height, and drop weight was performed to evaluate the utility of the benchtop device to replicate impact loading conditions which occurred in the cadaveric model.

Results

Several benchtop test groups replicated the cadaver group in number of strikes required for device insertion. The average cadaveric peak force, 13.03 kN, was replicated by three benchtop groups: 12 mm device height, 60 cm drop height, 0.75 lb drop weight; 12 mm device height, 60 cm drop height, 1.0 lb drop weight; and 14 mm device height, 60 cm drop height, 0.50 lb drop weight. The initial slope of the impact waveform was replicated best by 12 mm devices. Both the impact duration and impulse were lower in all benchtop groups than in cadaver testing.

Conclusions

This work validated the outfitting of an impact force sensor onto an interbody device insertion instrument as a reproducible, quantifiable method for collecting impact loading data in a cadaveric model. This benchtop device and methodology will aid in testing interbody devices relative to anticipated use conditions, enhance interbody device designs, and accelerate surgical technique refinement.