A THREE-DIMENSIONAL MORPOLOGICAL MEASUREMENT AND IN VITRO BIOMECHANICAL STUDY OF METATARSALS

Stress fracture of the metatarsal (MT) is often reported clinically. This study was aimed to measure and compare the three-dimensional (3D) morphological structure of five MTs, and investigate the in vitro biomechanics of five MTs under simulated stance phase. A total of seven foot-ankle samples of human cadavers were collected for this experiment. All samples were CT-scanned and 3D re-constructed for digital measurements. To simulate the stance phase, each sample was vertically loaded with 700-N through a material testing machine. The 3D-reconstruction-based measurement showed significant differences of the shaft length, vertical height, and inclination angle between the second MT and four others. Experimental strain measurements at dorsal MTs along the principal axis are all compressive. The values are respectively [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] micro-strain from the first to fifth MTs. This study proposed a new load condition of plantar-flexed simply supported beam to describe the MT loading mechanism. The second and third MTs have higher risk of stress fracture due to combined effects of inhomogeneous load distribution, unfavorable geometry and structure, and limited joint motion. This finding would be helpful for design of protective equipment.

A Multi-Axis Robotic Platform and Testing Protocol for Evaluating In Vitro Biomechanics of the Foot

The purpose of this study was to develop a cadaveric model for evaluating the relative motion across joint segments in the foot under simulated physiologic loading conditions. The specific aims were to 1) Develop a multi-axis testing platform that simulates three-dimensional (3D) loading conditions through the foot and ankle complex (Achilles load, tibial compression, and internal/external rotation) in a sequential or simultaneous manner, and 2) Evaluate and compare the three-dimensional (3D) kinematics between specific bones of interest in the foot for each individual cadaveric specimen.

Development of a Finite Element Lumbar Segment Model for Simulation of Coupled Loading Conditions Validated With In Vitro Experimental Studies

The traditional approach for evaluating the biomechanics of the spine, both experimentally and computationally, is through a series of planar loading scenarios that are reduced to sagittal (flexion/extension), frontal (lateral bending), and transverse (axial) planes of movement [1]. However, coupled movements occur through daily living activities that place further demands on a spinal device beyond simple planar movements. The objective of this study was to investigate the in vitro biomechanics of the L4-L5 lumbar motion segment unit (MSU) under the coupled loading conditions, and to use the experimental data to validate a high-fidelity non-parametric finite element (FE) model of the L4-L5 lumbar MSU.

Biomechanical Comparison of Lumber Disc Prostheses: ProDisc-L, Charité, and Maverick Disc Implant Systems

Interest in lumbar disc arthroplasty as an alternative to fusion surgery continues to grow. The goal of disc arthroplasty is to replace the diseased disc while preserving and/or restoring motion at the operated spinal level. Different paradigms exist in the design of total disc arthroplasty devices. The purpose of this study was to compare the in vitro biomechanics of a more constrained ball-and-socket design (Prodisc-L, Synthes Spine and Maverick, Medtronic) and a less constrained mobile-bearing design (Charité, DePuy). The biomechanical performances of the disc prostheses were compared to the fused and harvested spine conditions.