Statistical shape analysis of gravid uteri throughout pregnancy by a ray description technique.

In order to study the anatomical variability of the uterus induced by pregnancy, a parametrization of gravid uterine geometry based on principal component analysis (PCA) is proposed. Corresponding meshes used for PCA are created by a ray description technique applied to a reference mesh. A smoothed voxel-based methodology is applied to determine the reference mesh from a database of 11 real shapes produced by the FEMONUM project. The ray-based correspondence technique is compared to two existing methods (He, Giessen) as well as a proposed mixed method. Principal component analysis results are based on a database of 11 existing shapes. Results of the parametrization show that 90% of the total variance of the database can be represented with four new shape parameters and that a wide spectrum of shapes can be generated. Graphical Abstract Proposed correspondence technique compared to existing methods.

Trends in Trapeziometacarpal Implant Design: A Systematic Survey Based on Patents and Administrative Databases.

Hand function is inseparably linked to the condition of the thumb. The trapeziometacarpal (TMC) joint that provides the different movements of opposition is one of the joints most affected by osteoarthritis, which causes an irreversible deformation of the bone. The ideal thumb carpometacarpal implant must restore range of movement, prevent complications, be biocompatible, and have good mechanical properties (ie, low wear, high corrosion resistance, and osteointegration properties where it is anchored in a bone). The integrity of the implant and the surrounding biological structures must be long-lasting and withstand constant stresses induced by the prosthesis. Three main types of implant systems for the thumb are currently clinically available; others are under investigation in human subjects. This systematic review is based on administrative databases, patents, the literature, and information from orthopedic companies. It provides a summary of strategies and design changes and an overview of the biomechanical characteristics of currently available carpometacarpal implants for treating osteoarthritis of the thumb.

A voxel-based method for designing a numerical biomechanical model patient-specific with an anatomical functional approach adapted to additive manufacturing.

Here, we describe an original and efficient geometry design approach, based on voxels resulting in a validated model for printability in additive manufacturing. The proposed approach is also designed to be accessible to non-specialists as it does not require specialist skills in computer-assisted-design (CAD). It focuses on biomedical applications, particularly the geometry design of a configurable digital biomechanical model with selected anatomical features based on medical imaging compatible with customization, as might be needed for prosthetic elements. The methodology is based on two main steps. First, an accessible parametrization to medical employees of a configurable biomechanical model is matched specifically to the patient. The configurable model is designed to palliate any kind of potential lack of information from the Digital Imaging and Communication in Medicine (DICOM) file of the medical imaging or partial topological defects but with the least and sufficient number of parameters. For this purpose, the configurable model is segmented in topological areas with a complexity facing solely the desired specification, without regards of potential numerical errors prior AM such as boundary edges, intersecting faces and non-manifold edges. The second step is the voxel-based modelling, easily accessible for medical employees unfamiliar with CAD. Voxels stores the geometric information in a discrete format to facilitate customization by topological operations such as addition and subtraction. The voxelization representation coupled with a smoothing filter, results in a more realistic, robust and closed triangulated model, freed from errors of printability. This method is presented in the context of a trapezium replacement prosthesis prior to selective laser melting (SLM) and diverse post-treatments.