Blood flow signals through the bone cortex on ultrasonography can be used as a screening test for detecting bone marrow lesions on magnetic resonance imaging in patients with early knee osteoarthritis

Purpose: Blood flow signals (BFSs) through the bone cortex on ultrasonography (US) and bone marrow lesions (BMLs) detected on magnetic resonance imaging (MRI) can be used to assess bone lesions; however, no studies have reported their relationship. Therefore, this study aimed to assess whether BFSs through the bone cortex on US can serve as a screening test for detecting BMLs on MRI in patients with early knee osteoarthritis (OA).

Methods: This study enrolled patients with knee joint pain who were diagnosed with early knee OA between January 2018 and January 2024. We targeted 77 patients who underwent MRI and in whom the presence or absence of BFSs through the bone cortex was confirmed on US. The association between BFSs and BMLs was evaluated using the chi-square test, and the sensitivity and specificity of BFSs for detecting BMLs on MRI were calculated.

Results: The chi-square test showed that BFSs and BMLs were significantly associated in the femur and tibia (femur: χ² [1] = 52.9, p < 0.001; Tibia: χ² [1] = 44.8, p < 0.001). The sensitivity, specificity, positive predictive value, and negative predictive value of BFSs for detecting BMLs on MRI were 85.0%, 96.5%, 89.5%, and 94.8%, respectively, for the femur, and 84.0%, 92.3%, 84.0%, and 92.3%, respectively, for the tibia.

Conclusion: BFSs through the bone cortex on US can be used as a screening test for detecting BMLs on MRI in patients with early knee OA.