Correlations of Medial Joint Space Width on Fixed Flexed Standing CT and Radiographs with Cartilage and Meniscal Morphology on MRI

OBJECTIVE: To assess whether medial tibiofemoral joint space width (JSW) on 3D standing CT (SCT) correlates more closely with MRI cartilage morphology (CM) and meniscal scores than does radiographic 2D JSW.

METHODS: Participants in the Multicenter Osteoarthritis Study (MOST), who had standing fixed-flexion PA knee radiographs, were recruited. Medial tibiofemoral 3D JSW on SCT and 2D JSW on fixed flexion radiographs were compared with medial tibiofemoral cartilage and meniscal morphology using the WORMS system. Associations between the area of the articular surface with 3D JSW <2.5mm on SCT, radiographic minimal 2D JSW and the WORMS-CM and meniscal scores were assessed using Spearman's rho.

RESULTS: For the 19 participants included (33 knees), mean±SD age was 66.9±5.4, BMI was 29.5±4.4 kg/m(2) , 42.1% were female and KL grades were 0 (21.2%), 1 (36.4%), 2 (18.2%), and 3 (24.2%). The articular surface area with 3D JSW<2.5mm on SCT correlated with WORMS-CM scores for the central medial tibia (rs =0.84, p<0.001) and central medial femur (rs =0.60, p<0.007) and posterior medial meniscal tear (rs =0.39, p<0.026), as did other cut-points for 3D JSW. Correlations with radiographic minimal 2D JSW were -0.66, -0.52, and -0.40 respectively, differing from SCT only for tibial cartilage (p=0.001).

CONCLUSIONS: Greater surface area with a low JSW, measured by SCT, correlates more strongly with the severity of tibial cartilage lesions, while correlating with medial femoral cartilage and meniscal damage to a similar extent as radiographic minimal JSW. SCT may enable valid stratification of participants in clinical trials, through quickly and inexpensively characterizing OA features. This article is protected by copyright. All rights reserved.