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F-AHG-4: Modelling the proximal femur and the calcar femorale

This project is motivated by treating adolescents with hip injuries, middle- and older-aged adults being considered for hip replacement, and elderly adults who suffer hip fractures. The calcar femorale is a dense strip of bone where the femoral neck joins the femoral shaft. It provides structural support when standing, may act as a wedge in fractures, and in X-rays may potentially be a valuable orientation guide, particularly when imaging was not performed in the ideal plane. It is this last point we are directly hoping to explore with the current project.

The idea is to build a statistical shape model of the proximal femur, including the calcar femorale, based on clinical CT data. The project would suit a student who has taken Module 3G4 and Project GG2, though neither is a strict prerequisite. It will involve programming in C++, and the opportunity to learn more about computational geometry and graphics. Your work would help guide the diagnosis and management of the adolescent injury known as Slipped Capital Femoral Epiphysis, the design of hip replacement implants, and the understanding of hip fracture patterns.

This project is offered in collaboration with Dr Ken Poole (Rheumatology, Addenbrooke's Hospital) and Dr Jason Hoellwarth (Orthopaedic Surgery, Pittsburgh, USA). Dr Hoellwarth would be available via email or Skype for consultation to assist in understanding the clinical translation and relevance of the project.

Given sufficient segmented femurs, principal component analysis can be used to build a statistical shape model, revealing the significant modes of variation in the population. The example here is the second shape mode in a study of 125 femurs.
The goal of this project is to add the calcar femorale to the shape model. The resulting model would allow us to address many interesting questions concerning hip geometry and strength. Of particular interest is whether an orthopedic surgeon can look at a Lauenstein frog-leg hip X-ray, identify the calcar, and use its trajectory as a built-in anatomical guide of the axis of the proximal femur, against which angles of the epiphysis can be compared. Such an approach was proposed in 1988, but has not been verified rigorously using 3D CT data.
© Cambridge University Engineering Department
Information provided by Andrew Gee
Last updated: April 2018