Direct Comparison of Fixed Flexion Radiography and MRI in Knee Osteoarthritis: Responsiveness Data from the Osteoarthritis Initiative.
ABSTRACT OBJECTIVE: Minimum radiographic joint space width (mJSW) represents the FDA standard for demonstrating structural therapeutic benefits for knee osteoarthritis (KOA), but only shows moderate responsiveness (sensitivity to change). We directly compare the responsiveness of MRI-based cartilage thickness and JSW measures from fixed-flexion radiography (FFR) and explore the correlation of region-matched changes between both methods. METHODS: 967 knees of Osteoarthritis Initiative participants with radiographic KOA were studied: 445 over one year with coronal FLASH MRI and FFR, and 375/522 over one /two years with sagittal DESS MRI and FFR. Standardized response means (SRM) of cartilage thickness and mJSW were compared using the sign-test. RESULTS: With FLASH MRI, SRM was -0.28 for medial compartment (MFTC) cartilage loss vs. -0.15 for mJSW, and -0.32 vs. -0.22 for the most sensitive MRI subregion (central MFTC) vs. the most sensitive fixed location JSW(X=0.25) . With DESS MRI, one-year SRM was -0.34 for MFTC vs. -0.22 for mJSW and -0.44 vs. -0.28 for central MFTC vs. JSW(X=0.225). Over two years, the SRM was significantly greater for MFTC than for mJSW (-0.43 vs. -0.31, p=0.017) and for central MFTC than for JSW(X=0.225) (-0.51 vs. -0.44, p<0.001). Correlations between changes in spatially matched MRI subregions and fixed location JSW were not consistently higher (r=0.10-0.51) than those between non-matched locations (r=0.15-0.50). CONCLUSIONS: MRI displays greater responsiveness in KOA than JSW FFR-based JSW, with the greatest SRM observed in the central medial femorotibial compartment. Fixed-location radiographic measures appear not capable of determining the spatial distribution of femorotibial cartilage loss.
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ABSTRACT: Radiographic joint space width (JSW) is considered the reference standard for demonstrating structural therapeutic benefits in knee osteoarthritis. Our objective was to determine the proportion by which 3D (regional) meniscus and cartilage measures explain between-knee differences of JSW in the fixed flexion radiographs. Segmentation of the medial meniscus and tibial and femoral cartilage was performed in double echo steady state (DESS) images. Quantitative measures of meniscus size and position, femorotibial cartilage thickness, and radiographic JSW (minimum, and fixed locations) were compared between both knees of 60 participants of the Osteoarthritis Initiative, with strictly unilateral medial joint space narrowing (JSN). Statistical analyses (between-knee, within-person comparison) were performed using regression analysis. A strong relationship with side-differences in minimum and a central fixed location JSW was observed for percent tibial plateau coverage by the meniscus (r=.59 and .47; p<.01) and central femoral cartilage thickness (r=.69 and .75; p<.01); other meniscus and cartilage measures displayed lower coefficients. The correlation of central femoral cartilage thickness with JSW (but not that of meniscus measures) was greater (r=.78 and .85; p<.01) when excluding knees with non-optimal alignment between the tibia and X-ray beam. 3D measures of meniscus and cartilage provide significant, independent information in explaining side-differences in radiographic JSW in fixed flexion radiographs. Tibial coverage by the meniscus and central femoral cartilage explained two thirds of the variability in minimum and fixed location JSW. JSW provides a better representation of (central) femorotibial cartilage thickness, when optimal positioning of the fixed flexion radiographs is achieved.European journal of radiology 09/2013; 82(12). DOI:10.1016/j.ejrad.2013.08.041 · 2.16 Impact Factor
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ABSTRACT: Determine the effect of loading upon MRI-based mean medial femorotibial cartilage thickness (mMFT_th) and radiograph-based minimum joint space width (mJSW), and determine loading's effect on the relationship between these measures. MRI and radiographs were analyzed of 25 knees in weight-bearing and non-weight-bearing conditions. 8 subjects had a Kellgren-Lawrence (KL) grade of 0, indicating no evidence of radiographic OA. The rest were KL = 2 or KL = 3, indicating mild to moderate OA. The change from unloaded to loaded conditions was calculated. Joint space measures decreased from unloaded to loaded conditions for both radiographs (mJSW = 3.29 mm unloaded to 3.16 mm loaded, p<0.05) and MRI (mMFT_th = 2.70 mm unloaded to 2.55 mm loaded p<0.001). The mean absolute difference measured from radiographs was larger for the OA group than the control group, at -0.20 mm for OA vs. +0.01 mm for control. Loaded X-ray and loaded MRI joint space values from our study were no better correlated to one another than loaded X-ray and unloaded MRI. Knee loading does not add a very significant value to the study of joint space on healthy knees, but loading may play a role in the study of OA knees. Unloaded MRI assessments of cartilage thickness are as correlated to loaded JSW as to loaded MRI measurements. More study is necessary to determine whether loaded MRI adds significant value to the study of OA progression.Osteoarthritis and Cartilage 09/2013; 21(12). DOI:10.1016/j.joca.2013.09.006 · 4.66 Impact Factor
- Arthritis & Rheumatology 11/2013; 65(11). DOI:10.1002/art.38086 · 7.87 Impact Factor