Objective: To evaluate in knee osteoarthritis (OA) patients the size changes in bone edema and cysts over 24 months, and to contrast these changes with cartilage volume loss using quantitative MRI.
Methods: 107 knee OA patients, selected from a large trial evaluating the effect of a bisphosphonate, were analyzed by MRI at baseline and 24 months. Assessments of subchondral bone edema and cysts, and cartilage volume were done.
Results: At baseline, 86 patients showed the presence of at least one type of bone lesion: 71 edema, 61 cysts and 51 both. At 24 months, although not statistically significant, the edema total size change increased by 2.09 ± 15.03 mm, and the cyst by 1.09 ± 8.13 mm; mean size change for the edema was +0.38 ± 2.18 mm and -0.10 ± 4.36 mm for the cyst. When analyzed according to subregions, an increase was found for the cyst size in the trochlea (+0.67 ± 2.74 mm, p=0.02) and in the lateral tibial plateau (+0.15 ± 0.83 mm, p=0.09), and for the edema size in the medial tibial plateau (+1.73 ± 8.11 mm, p=0.05). At 24 months, significant correlations were seen between the loss of cartilage volume and edema size change in the medial condyle (-0.40, p=0.0001) and the medial tibial plateau (-0.23, p=0.03), and the changes in cyst size in the medial condyle (-0.29, p=0.01). A multivariate analysis showed that the edema size change was strongly and independently associated with medial cartilage volume loss (-0.31, p=0.0004).
Conclusion: These data demonstrate that bone lesions are prevalent in knee OA. The correlation of the edema and cyst size increase in the medial compartment over time with a greater loss of cartilage volume in this area underlines the importance of subchondral bone lesions in OA pathophysiology.
- bone lesions
- cartilage volume loss
- knee OA