Bone marrow lesions in people with knee osteoarthritis predict progression of disease and joint replacement: a longitudinal study.

Objectives: The presence of bone marrow lesions (BMLs) has been linked to pain and progression of knee OA. The aim of this study was to determine the relationship between BMLs and longitudinal change in tibial cartilage volume and risk of knee joint replacement in subjects with knee OA.
Methods: One hundred and nine men and women with symptomatic knee OA were recruited. The same knee was imaged using MRI at baseline and ∼2 years later. Tibial cartilage volume and BMLs were measured. Knee joint replacement over 4 years was determined.
Results: The mean age of the subjects at baseline was 63.2 (s.d. 10.3) years. BMLs were present in 66% of the subjects. Cross-sectionally, BMLs were negatively associated with both medial (regression coefficient -121.4; 95% CI -183.8, -859.1; P<0.001) and lateral (regression coefficient -142.1; 95% CI -241.8, -42.4; P=0.01) tibial cartilage volume data. Longitudinally, for every 1-score increase in baseline BML severity (range 0-4), the annual total tibial cartilage loss was increased by 1.14% (95% CI 0.29%, 1.87%; P=0.01). The risk of knee joint replacement over 4 years increased with increasing BML score (odds ratio 1.57; 95% CI 1.04, 2.35; P=0.03).
Conclusion: The prevalence and severity of BMLs are associated with less tibial cartilage volume and greater cartilage loss over 2 years. Moreover, severity of BMLs was positively associated with risk of knee joint replacement over 4 years. This provides further support for the importance of BMLs in identifying those with OA most likely to progress. Identifying factors that prevent or reduce the severity of BMLs may provide an important target in the prevention of disease progression and treatment of OA, and the subsequent need for arthroplasty.