A 2-year evaluation of disease progression by quantitative magnetic resonance imaging in a large primary osteoarthritic patient population

The aim of this study was to expand our previous work assessing cartilage volume changes on knee osteoarthritic (OA) patients over time by quantitative magnetic resonance imaging (MRI).

A subset of 110 patients, chosen from a large clinical trial evaluating the impact of a bisphosphonate on OA knee, was studied. The overall patient population (n = 1232) represented a standard study with the mean age of 60.5 years, 61% female, and an average body mass index of 30.3 kg/m². Patients with KL Grade IV radiographs were excluded. MRIs of the knee were performed at baseline, 12 months and 24 months. The images were arranged randomly and quantified by readers blinded to the time sequence. Total cartilage volumes and cartilage from the medial and lateral compartments were analyzed. Data are presented for the population that had all three sets of MRIs (n = 107 patients). Data on cartilage volume changes with time are presented as pooled data.

The mean losses of knee OA cartilage volume in percentage from baseline, computed at all follow-up time points, were all statistically significantly different from zero and are similar to those previously obtained from a pilot study of 32 patients [1]. Three populations described as fast progressors (n = 11 patients; -13.2% of total cartilage), intermediate progressors (n = 48; -7.2%) and slow progressors (n = 48; -2.3%) were identified based on loss distribution at 24 months.

These data support our previous observations in a smaller cohort of patients, showing MRI to be a precise and sensitive measure, able to reliably detect significant changes in human knee OA cartilage volume over time; as early as 12 months. Moreover, the percentage loss of cartilage volume further validates, by its statistical power, the results of our pilot study.

Table 1