First carpometacarpal osteoarthritis (CMC1 OA) is one of the most common forms of OA and is a significant source of pain and disability for patients. Discrepancies between traditional imaging modalities and patient reported outcomes have led researchers to develop objective point of care-based imaging tools for assessing OA progression and treatment response. This thesis aims to describe the development and validation of a semi-submerged mechanical threedimensional ultrasound device against the current clinical gold standard of magnetic resonance imaging (MRI). Additionally, this thesis will explore the relationship between the morphological presentation of synovitis, pain, physical function, and various semi-quantitative grading systems used in a CMC1 OA patient population.

Chapter 2 described the validation of the 3D US device which was conducted on a series of geometric and volumetric imaging phantoms, as well as a population of ten CMC1 OA patients. Images of the ten patients were acquired using a 3.0 Tesla MRI and our 3D US device. Tworaters manually segmented areas of synovial effusion and membrane hypertrophy during two separate sessions to evaluate intra- and inter-rater reliability. The results showed that 3D US had a strong concurrent validity with MRI and that it demonstrated excellent rater reliability. This indicates that 3D US shows great potential to provide clinicians with a quantitative method for monitoring synovitis in the small joints of the hand.

Chapter 3 presented in this thesis explored the implications of synovitis morphology presented in 3D US images and investigated synovial tissue volume as a possible predictor of CMC1 OA stage as determined by x-ray radiographic grading systems. Eaton-Littler (x-ray) and OMERACT (US) semi-quantitative grading systems were used to indicate OA and synovitis severity. These values were compared to the Australian Canadian Osteoarthritis Hand Index for patient reported pain and disability, pinch grip force, synovial tissue volume, age and sex to determine which would be the most significant indicator patient reported pain.US images of CMC1 synovitis were analyzed and three distinct morphologies were identified based on location, volume and features of synovial effusion and hypertrophy. This study demonstrated that pinch grip was the most significant indicator of pain in CMC1 OA patients.