Development of an arthroscopy-based water-jet ultrasound indentation system for the morphological, acoustic and mechanical assessment of articular cartilage degeneration

xxii, 135 leaves : ill. ; 30 cm.PolyU Library Call No.: [THS] LG51 .H577P BME 2012 HuangOsteoarthritis (OA) is a common disease related to the joints. Millions of patients especially the elderly in the world are suffering both physically and economically from this disease. Cartilage is one of the main tissues that are significantly affected by this disease. Traditionally, plain X-ray radiography and arthroscopy can be used for the diagnosis of cartilage degeneration. However, significant thinning and erosion observed in X-ray imaging and arthroscopy are symptoms of the cartilage degeneration at an advanced stage when currently no effective treatment is available. In contrast, it is much more potential to treat the cartilage degeneration diagnosed at the early stage. Therefore, detection of the early cartilage degeneration is of critical importance but related instruments are still lacking in the field. The water-jet ultrasound indentation test is a specific technique that has been developed to use an ultrasound-based measurement to obtain morphological, acoustic and mechanical properties from the articular cartilage. These properties are potential indicators of the degeneration of cartilage with osteoarthritic change. In order to make this technique available for clinical applications, this study targets at developing an arthroscopy-based water-jet ultrasound indentation system, mainly a new arthroscopic probe, and corresponding measurement procedure for the purpose of quantitative assessment of the cartilage degeneration in intra-articular measurement. To achieve this goal, a two-step realization scheme was adopted in the study and corresponding experiments were conducted on phantom and cartilage samples to test the utility of the newly developed probe and measurement technique.For the first step development, a miniaturized probe was realized in an aluminous rod of 12 mm in diameter with the use of a small single element ultrasound transducer. At the second step, a real arthroscopy channel-based probe was successfully designed and fabricated with the aid of intra-articular ultrasound (IAUS) catheter transducer. The main design was realized at the tip of an arthroscopic trochar of 5.5 mm in diameter so that an intra-articular operation is possible for its operation in intact knee joints. Validation experiments were conducted on 28 silicone phantoms, 40 bovine patellar cartilage samples before and after enzymatic digestions, 40 opened rabbit knees sacrificed at different time points after the anterior cruciate ligament (ACL) transection surgery and 10 intact porcine knees before and after enzymatic digestion. The measured parameters mainly included the thickness, surface roughness, integrated reflection coefficient (IRC), stiffness and energy dissipation ratio (EDR) of the cartilage. These parameters were compared between normal and degenerated groups or among different groups with different severity of degeneration. Results from the validation experiments showed that the developed probe could be successfully applied in an intra-articular operation with the guide of arthroscopy and the ultrasound-based measurement was effective to differentiate the degeneration of articular cartilage. In conclusion, in this study an arthroscopy-based water-jet ultrasound indentation probe has been successfully designed and fabricated through a two-step development scheme. This newly developed probe could be used to detect the degeneration of articular cartilage in different models of cartilage degeneration. Future research may include the optimization of the probe design, tests on human cadaver cartilage samples in vitro and clinical trials on human subjects in vivo.Department of Biomedical EngineeringPh.D., Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, 201