Bad knees, we always thought, were the consequence of bad exercise, or at least excessive exercise. Now comes Gretchen Reynolds, writing in the New York Times about a study published in The British Journal of Sports Medicine, in which researchers looked at one family’s propensity for shredding anterior cruciate ligaments. Reynolds tell us that the report, part of a larger, ongoing study, focused on set of fraternal twin girls whose knee movements were videotaped while wearing reflective markers so that the angles of their knees during landing and cutting maneuvers could be analyzed. The Times reports that at the time of the taping, both athletes’ knees were healthy, but within a year, each had a catastrophic A.C.L. tear, as had an older sister, who wasn’t part of the study. The researchers learned that each of the fraternal twin girls’ knees had loose, flexible knee joints, and each angled at least one knee outward during landings and had narrower-than-average notches in the knee bone, where the A.C.L. attaches to the bone. Bottom line, says Reynolds, the researchers came away convinced that high risk for an A.C.L. tear is definitely heritable.
Read more in the New York Times.