Studies have shown that compared with the knee cartilage of normal individuals, the expression of NR1D1 and BMAL1 in the knee cartilage of osteoarthritis (OA) patients is relatively low, and the expression of Bmal1 is also lower in the OA rat model, which is negatively correlated with the severity of OA [19, 20]. This evidence concerns the gene BMAL1 and osteoarthritis.