Bone Marrow Lesion Etiology Examined in Knee Osteoarthritis

In women with symptomatic knee osteoarthritis (OA), bone marrow lesions (BMLs) can be prevented by maintaining systemic bone metabolism, according to study results published in Arthritis Research and Therapy.

Researchers conducted a single-center, cross-sectional study of Japanese women without radiographic evidence of knee OA. Participants were identified from a pool who volunteered to participate in the Iwaki Health Promotion Project, a community-based preventive medicine program. From a total of 1073 volunteers (441 men, 632 women), researchers identified 266 women to participate in the current study (mean age 54.9±9.6 years).

Researchers assessed knee symptoms using the Knee injury and Osteoarthritis Outcome Score (KOOS) and categorized participants as having a symptomatic knee or an asymptomatic knee. Knee OA presence was confirmed through weight-bearing and anterior-posterior radiographs of both knees. Within 1 week of examination, participants underwent magnetic resonance imaging of the right knee; BML severity was assessed via the Whole-Organ Magnetic Resonance Imaging Scoring method. Bone mineral density (BMD) was measured via forearm dual-energy x-ray absorptiometry evaluation, and blood samples were collected to determine bone marker levels.

Among the participants, 25.6% had symptomatic knees, and 35.3% of participants had BMLs in the knee joint. In those with symptomatic knees, multiple linear regression analysis found a negative association between BMD and BMLs (P =.014); no associations were noted in participants with asymptomatic knees.

In participants with BMLs, several bone marker levels were higher: in particular, bone alkaline phosphatase (BAP), type I procollagen N-terminal propeptide, tartrate-resistant acid phosphatase-5b, and pentosidine. Among individuals with symptomatic knees, BAP (P =.006) and type I procollagen N-terminal propeptide (P =.043) were significantly associated with BMLs. Similarly, BAP (P =.038) and tartrate-resistant acid phosphatase-5b (P =.011) were significantly associated with BMLs in individuals with asymptomatic knees.

The researchers noted several limitations for the study, including the lack of analysis of the femoral neck and lumbar spine, as well as the sex of the study population (all women) and the exploratory nature of the study.

“[B]ecause women with a symptomatic knee might be at a higher risk of cartilage loss and incidence of radiographic [knee OA], they showed a stronger relationship between BMD and BMLs than did women with an asymptomatic knee,” the researchers concluded. “These results indicate that future studies will need to determine the importance of maintaining systemic bone metabolism in women without radiographic abnormalities who have knee symptoms.”

Reference

Ota S, Chiba D, Sasaki E, et al. Symptomatic bone marrow lesions induced by reduced bone mineral density in middle-aged women: a cross-sectional Japanese population study. Arthritis Res Ther. 2019;21(1):113.