Osteoarthritis and degenerative cartilage diseases affect millions of people. Therefore, there is huge interest in developing new therapies to repair, replace and/or regenerate cartilage. This necessitates advances in techniques which make earlier non-invasive diagnosis and objective quantitative evaluations of new therapies possible. Most previous research has focused on the knee and neglected the ankle joint. Hence, the aims of this thesis are to describe and quantify the geometric properties of ankle cartilage, to evaluate joint contact characteristics and develop techniques which allow quantitative measurements to be made in vivo.
Chapters 3 and 6 describe the application of a high resolution stereophotography system for making highly accurate 3-D geometric models from which quantitative measurements of cartilage parameters and joint area contact can be made. Chapters 4 and 5 report the testing of image analysis algorithms designed to segment cartilage sensitive MR images. Work focused on initially on a semi-automated 2-D segmentation approach and subsequently on a pilot study of 3-D automated segmentation algorithm.
The stereophotographic studies were highly accurately and demonstrated that ankle cartilage thickness is greater than previously reported with the thickest cartilage occurring where cartilage injuries are most commonly seen. Furthermore, joint contact area is larger than previously believed and corresponds to the regions of the thickest cartilage over the talar shoulders. The image analysis studies show that it is possible to accurately and reproducibly segment the thin cartilage layers of the ankle joint using a semi-automated approach. The feasibility of a fully automated 3D method for future clinical use is also shown.
In conclusion this thesis presents novel methods for examining ankle articular cartilage in vitro and in vivo, showing that the thickest cartilage occurs in highly curved regions over the shoulders of the talus which correspond to regions of greatest contact. Importantly, the image analysis techniques may be used for future clinical monitoring of patients sustaining cartilage injuries or undergoing cartilage repair therapies
