The following is a summary of the “Improved responsiveness to change in joint space width over 24-month follow-up: comparison of 3D JSW on weight-bearing CT vs 2D JSW on radiographs in the MOST study,” published in the March 2023 issue of Osteoarthritis and Cartilage by Segal, et al.

Knee osteoarthritis (OA) structural change has traditionally been measured by radiographic joint space width (JSW). As an alternative, monitoring 3D JSW on loaded CT scanners may help address the method’s lack of reactivity (WBCT). This research evaluated the reactivity of radiographic 2D JSW to that of 3D JSW data obtained using WBCT. The 144-month and 168-month visits in the Multicenter Osteoarthritis Study included the acquisition of standing, fixed-flexion knee radiographs (XR) and WBCT. Both X-ray and WBCT scans included a measurement of the tibiofemoral joint angular separation (JSW). 

SRM for change in JSW at specified mediolateral positions (JSWx) on both modalities and in the central medial and lateral femur (CMF/CLF) and tibia (CMT/CLT) and anterior and posterior tibia (AMT/ALT, PMT/MLT) evaluated on WBCT images was used to define responsiveness to change. Around 265 people (58.1% female) were measured using JSWx at both the baseline and 24-month points. On coronal WBCT, the medial tibiofemoral compartment responded better to 3D JSWx (SRM range: -0.18, -0.24) than it did to 2D JSWx (-0.10, -0.16). 

Compared to medial and lateral 2D JSWx, the responsiveness of 3D JSW subregional mean (-0.06, -0.36) and maximal (-1.14, -1.75) CMF and CMT and maximal CLF/CLT 3D JSW alterations was statistically significant (P≤ 0.002). Compared to radiographic assessments, subregional 3D JSW on WBCT is much more sensitive to 24-month changes in tibiofemoral joint structure. Subregional 3D JSW on WBCT may be superior than XR measures for monitoring structural changes in OA over a 24-month period.

Source: sciencedirect.com/science/article/abs/pii/S1063458422009566