Testosterone And ACL Tears

Why is it that women are up to 10 times more likely than men to  tear an ACL? Researchers at Johns Hopkins think it may have something to do with testosterone. A Johns Hopkins news release reports that researchers at the school found that normal male rats with natural supplies of testosterone had stronger ACLs than those that had been castrated and no longer produced the hormone. Wait, there’s more. Researchers have also found that estrogen — a predominantly female hormone — reduces ACL strength in rats, and that knee ligaments in both sexes contain receptors for testosterone. The researchers found that it took more force — 34.5 newtons, compared to 29.2 newtons — to tear the ACLs from mice with normal levels of testosterone than from rats that had been castrated, indicating that the ligaments were stronger.