CD9 and osteoporosis: When the number of genes was 10, the peak MCC was 0.386, and these 10 genes were considered to be characteristic genes related to metabolism in osteoporosis, including GPR31, GATM, DDB2, ARMCX1, RPS6, BTBD3, ADAMTSL4, COQ6, B3GNT2, and CD9. Subsequently, we visualized violin plots based on the expression of 10 candidate genes in different subtypes of osteoporosis.