Objective:

Characterize 3D strain and deformation in relation to the microstructural organization of fibers in human medial when dynamically compressed. Determine among the freely available algorithms for DVC which one is best performing to determine meniscus microstructural response to in situ loading. Compare mechanical properties of menisci form different donors.

Background:

Osteoarthritis (OA) is a "wear-and-tear" type of degenerative arthritis that mostly occurs in people over 50 years. Knee OA is associated with the degeneration of the meniscus. The meniscus, a crescent-shaped disc of fibrocartilage that is located between the surfaces of the femur and tibia in the medial and lateral compartments of the joint. It is composed of water and specifically hierarchically arranged collagen, which serves to distribute the load in the knee. Structural and mechanical changes are known to occur in the meniscus due to OA, however, the details of how the degeneration evolves are still unknown. Digital volume correlation (DVC) is a method to track translations of small sub-volumes between two subsequent 3D images. A matching is performed between subsequent loading-step volumes based on the similarity of the grayvalue patterns. DVC outputs are the internal displacements for multiple sub-volumes, based on which tensor strain fields can be computed and the evolution during loaded tracked. However, DVC was never performed on menisci imaged by dynamic phase contrast, so parameters will need specific optimization, and refined details of the expected outcome are unknown.

Approach:

The candidate will perform DVC of dynamic X-ray phase contrast imaging datasets of human meniscus. Focus is on identifying the best DVC algorithm and parameters to determine micro deformations and strain distribution in the tissue during loading.

Student background:

knowledge of 3D image analysis and programming.

For more info, please contact the Biomechanics group, Hanna Isaksson, hanna.isaksson@bme.lth.se



A) setup for in situ loading at TOMCAT. B) Loading curve. C) Meniscus during compression. Orientation distribution along the meniscus longitudinal plane is shown as colormap. D) Schematic of the DVC procedure.