Long term evaluation of disease progression through the quantitative magnetic resonance imaging of symptomatic knee osteoarthritis patients: correlation with clinical symptoms and radiographic changes

Abstract

The objective of this study was to further explore the cartilage volume changes in knee osteoarthritis (OA) over time using quantitative magnetic resonance imaging (qMRI). These were correlated with demographic, clinical, and radiological data to better identify the disease risk features. We selected 107 patients from a large trial (n = 1,232) evaluating the effect of a bisphosphonate on OA knees. The MRI acquisitions of the knee were done at baseline, 12, and 24 months. Cartilage volume from the global, medial, and lateral compartments was quantified. The changes were contrasted with clinical data and other MRI anatomical features. Knee OA cartilage volume losses were statistically significant compared to baseline values: -3.7 +/- 3.0% for global cartilage and -5.5 +/- 4.3% for the medial compartment at 12 months, and -5.7 +/- 4.4% and -8.3 +/- 6.5%, respectively, at 24 months. Three different populations were identified according to cartilage volume loss: fast (n = 11; -13.2%), intermediate (n = 48; -7.2%), and slow (n = 48; -2.3%) progressors. The predictors of fast progressors were the presence of severe meniscal extrusion (p = 0.001), severe medial tear (p = 0.005), medial and/or lateral bone edema (p = 0.03), high body mass index (p < 0.05, fast versus slow), weight (p < 0.05, fast versus slow) and age (p < 0.05 fast versus slow). The loss of cartilage volume was also slightly associated with less knee pain. No association was found with other Western Ontario McMaster Osteoarthritis Index (WOMAC) scores, joint space width, or urine biomarker levels. Meniscal damage and bone edema are closely associated with more cartilage volume loss. These data confirm the significant advantage of qMRI for reliably measuring knee structural changes at as early as 12 months, and for identifying risk factors associated with OA progression.

Figure 1

Changes in osteoarthritis cartilage volume percentage of loss from baseline after 24 months for each patient for the global knee and medial compartments of the three subgroups identified in the cluster analysis: slow (n = 48), intermediate (n = 48), and fast (n = 11) progressors. The global (and medial) volume loss at all the different time points were -2.3 ± 0.4% (-3.2 ± 0.6%) for the slow progressors, -7.2 ± 0.6% (-9.9 ± 0.1%) for the intermediate progressors, and -13.2 ± 0.4% (-21.5 ± 0.1%) for the fast progressors; the intermediate and fast progressor subgroups were found to be statistically significant when compared to baseline (t test). *p < 0. 001; **p < 0.0001.

Figure 2

Scatter plot contrasting the changes in the medial compartment cartilage volume versus minimum joint space width measured by standardized radiograph at 24 months for 107 OA patients. Subgroups of slow (black), intermediate (dark gray), and fast (light gray) progressors are identified. No correlation between the cartilage volume and the minimum joint space width was found.