Background: Radiographic joint space width (JSW) is considered the reference standard for demonstratingstructural therapeutic benefits in knee osteoarthritis. Our objective was to determine the proportion bywhich 3D (regional) meniscus and cartilage measures explain between-knee differences of JSW in thefixed flexion radiographs.Methods: Segmentation of the medial meniscus and tibial and femoral cartilage was performed in doubleecho steady state (DESS) images. Quantitative measures of meniscus size and position, femorotibial carti-lage thickness, and radiographic JSW (minimum, and fixed locations) were compared between both kneesof 60 participants of the Osteoarthritis Initiative, with strictly unilateral medial joint space narrowing(JSN). Statistical analyses (between-knee, within-person comparison) were performed using regressionanalysis.Results: A strong relationship with side-differences in minimum and a central fixed location JSW wasobserved for percent tibial plateau coverage by the meniscus (r = .59 and .47; p < .01) and central femoralcartilage thickness (r = .69 and .75; p < .01); other meniscus and cartilage measures displayed lowercoefficients. The correlation of central femoral cartilage thickness with JSW (but not that of menis-cus measures) was greater (r = .78 and .85; p < .01) when excluding knees with non-optimal alignmentbetween the tibia and X-ray beam.Conclusion: 3D measures of meniscus and cartilage provide significant, independent information inexplaining side-differences in radiographic JSW in fixed flexion radiographs. Tibial coverage by the menis-cus and central femoral cartilage explained two thirds of the variability in minimum and fixed locationJSW. JSW provides a better representation of (central) femorotibial cartilage thickness, when optimalpositioning of the fixed flexion radiographs is achieved.
- Cartilage morphometry
- Fixed flexion knee radiography
- Joint space width
- MRI quantitative imaging
- Meniscus morphometry
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging