EVALUATION OF 3D ULTRASOUND AS A TOOL TO EXAMINE SYNOVITIS VOLUME AND MORPHOLOGY IN RELATION TO PATIENT-REPORTED OUTCOMES

Radiography is the primary imaging tool used to assess and monitor osteoarthritis (OA) in the first carpometacarpal joint (CMC1). However, studies have reported discrepancies between radiographic evidence of OA and patient-reported symptoms such as pain and disability. These discrepancies have been attributed to the lack of soft-tissue contrast associated with radiography in addition to the heterogeneous nature of osteoarthritis as a disease1. Synovitis has been associated with pain and disability and has been proven to be a driver of osteoarthritis disease progression2. 3D ultrasound has been validated for measuring synovial tissue volume in CMC1 OA patient, more work is required to examine sonographic features associated with CMC1 OA in a cohort of patients, including effusion morphology and tissue quality. Nine-teen CMC1 OA patients were recruited by an experienced hand surgeon and a rheumatologist. A 3D ultrasound (3D US) device and a 14L-5 linear probe were used to acquire 3D US image of the CMC1 joint of these patients. 2D US images were acquired and graded using the Outcome Measures in Rheumatology (OMERACT) semi-quantitative grading scales. Pain and disability interference was quantified using the Australian Canadian Hand Osteoarthritis Index. A two-point pinch grip test was conducted to determine grip force. A descriptive analysis was used to describe observed changes in synovial tissue morphology and volume as various imaging grading scales differ, and how these changes are related to outcomes of pain and functional strength. Three distinct OA phenotypes were distinguished by synovial tissue margin properties, synovial tissue volume, and pathophysiological appearance (effusion vs. hypertrophy) as can be seen in Table 1. Patients who presented with moderate synovial tissue volumes comprised predominately of synovial effusion (effusion dominant) had the lowest average pain interference scores and highest functional scores. These patients presented with uniform concave morphology of their joint effusion. In comparison, the second group of patients presented with more diffuse effusion morphology and increased hypertrophic tissue. These patients also had increased pain interference scores and decreased pinch grip values (Table 1). The last group of patients presented with predominantly osteochondral pathology with increased osteophyte presentation, decreased joint space, and decreased synovial tissue volumes. These patients also had the highest pain interference scores and weakest pinch grip forces (Fig.1). The results of this study indicate that morphological differences between signs of synovitis demonstrate that the relationship between disease progression, patient-related outcomes, and image-based evidence of OA in the CMC1 joint is complex. The structures involved change as the disease progresses to more severe stages as well as between bouts of inflammation and varies between patients. 3D US can provide potentially valuable imaging characteristics for monitoring OA. For any figures or tables, please contact the authors directly.