• Abstract 1067: Bone Marrow Lesions Associated with More Rapid Cartilage Loss

Abstract 1067 Increase in Bone Marrow Lesions is Associated with More Rapid Cartilage Loss: A Longitudinal MRI Study
Hunter, Zhang, Felson et al

In previous studies by this group, bone marrow lesions as seen on baseline knee MRI correlated with baseline knee pain as well as progression of radiographic knee OA in the ipsilateral compartment. In the current study, Hunter et al examine the relationship between bone marrow edema lesions and rate of cartilage loss on follow-up MRI scanning.

Methods: Participants were recruited from outpatient clinics in and around the Boston, MA area. Participants underwent MRI scanning of both knees at baseline, and again after 15 and 30 months. MRI scans were assessed for bone marrow lesions and cartilage volume. Bone marrow lesions were scored in 12 separate knee regions (6 medial and 6 lateral) and graded 0-3 for size. Cartilage volume was scored from 0 (normal) to 6 (no cartilage) in the same 12 knee regions.

Long limb films were obtained at 15 months to assess for mechanical alignment.

Results: Of the 146 participants, the mean age was 66 years. 26% were male. Mean body mass index (BMI) was 31.4. 75% had bone marrow lesions at baseline. On subsequent repeat MRI, 3% had a reduction in bone marrow lesions. 57% had no change. 25% had bone marrow lesions with net increase of 1-2 units, 15% increases of 3 or more units. In terms of cartilage volume, 62% of participants had net cartilage loss.

For the knees with increases in bone marrow lesions, every one unit change in net size of medial tibio-femoral bone marrow lesions corresponded to a worsening of 1.32 units in cartilage score (0.27 after adjusting for malalignment). Every one unit change in net size of lateral tibio-femoral bone marrow edema lesions corresponded to a worsening of 0.72 units in cartilage score (0.54 after adjusting for malalignment).

In terms of alignment, varus malalignment correlated with bone marrow lesions in the medial tibio-femoral compartment. Likewise, valgus malalignment correlated with bone marrow lesions in the lateral tibio-femoral compartment.

Conclusions: Bone marrow lesions are unlikely to resolve but often increase in size. Enlarging bone marrow lesions are strongly associated with ipsilateral compartmental cartilage loss. The effect of knee malalignment partially explains these findings.

Editorial Comments: In a previous study, these investigators demonstrated that bone marrow lesions on knee MRI at baseline predict joint space narrowing in the ipsilateral compartment. The current study confirms these findings in demonstrating loss of cartilage volume by MRI in these same knees with persistent or enlarging bone marrow lesions. These data suggest that defects in subchondral bone in OA may be an initiating factor for subsequent cartilage loss. The finding that malalignment correlates with progressive cartilage loss and persistent bone marrow lesions does not prove causality and may be a result of the cartilage and bone loss.

All information contained within the Johns Hopkins Arthritis Center website is intended for educational purposes only. Physicians and other health care professionals are encouraged to consult other sources and confirm the information contained within this site. Consumers should never disregard medical advice or delay in seeking it because of something they may have read on this website.