Change in knee structure and change in tibiofemoral joint space width: a five year longitudinal population-based study

{Background: Change in knee cartilage volume is frequently used as a proxy for change in knee joint space width over time, but longitudinal data on these associations is limited. We aimed to determine whether change in knee cartilage volume, new or worsening meniscal extrusion (ME), meniscal tears and cartilage defects over 2.4 years correlated with change in joint space width (JSW) over 5 years in older community dwelling adults. Methods: Participants (n = 153) had their right knee imaged using MR imaging and x-ray at baseline, and after 2.4 years (MRI) and 5 years (x-ray). Cartilage volume, cartilage defects, meniscal extrusions and meniscal tears were assessed on sagittal T1-weighted fat-suppressed MRI. JSW was assessed using standard fixed semi-flexed view radiographs, and scored on those with adequate alignment. Results: Participants were 51-79 (mean 62) years old; 48 % were female. Cartilage volume reduced over time (medial -134 +/- 202 mu L/year, lateral -106 +/- 165 mu L/year, p < 0.001), as did JSW (medial -0.05 +/- 0.16 mm/year, lateral -0.12 +/- 0.24 mm/year, p < 0.001). In multivariable analysis, the only consistent predictor of change in JSW was new or worsening ME (medial tibia R-2 3.1 %