Evaluating High-Resolution Computed Tomography Derived 3-D Joint Space Metrics of the Metacarpophalangeal Joints Between Rheumatoid Arthritis and Age- and Sex-Matched Control Participants

Abstract Rheumatoid arthritis associated joint space narrowing is commonly evaluated through 2D X-ray radiographs. Unfortunately, changes and overlapping anatomy in smaller joints, such as those found within the hands, hinder conventional radiography. High resolution peripheral quantitative computed tomography (HR-pQCT), an un-paralleled in vivo X-ray-based imaging technique, provides 3D quantitative joint space metrics that may overcome limitations of 2D imaging. However, whether these metrics are sufficient for the differentiation between RA-associated joint changes and those influenced by age, sex, and obesity remains unknown. Therefore, we recruited a cohort of RA patients as well as age- and sex-matched healthy control participants and scanned their 2 nd and 3 rd metacarpophalangeal joints using HR-pQCT. HR-pQCT-derived 3D joint space metrics (volume, width, standard deviation of width, maximum width, minimum width, and asymmetry) were not significantly different between RA and control groups (p > 0.05). This may be explained by the few RA participants with evidence of radiographic damage included in this study. Joint space volume, mean joint space width (JSW), maximum JSW, minimum JSW were larger in males than females (p < 0.05), while maximum JSW decreased with age. However, there were no significant association between joint space metrics and BMI. Thus, as individuals with RA are expected to have more joint space narrowing, further research is necessary to determine whether additional factors (e.g. co-morbidities) or novel 3D JSW metrics can aid in the detection of early signs of joint space.