According to Fred Katz of MassLive, Boston Celtics rookie Robert Williams has an artery condition in both of his legs. Per their sources, the condition is “not too serious”.
Williams is dealing with popliteal artery entrapment syndrome, or PAES, which is commonly found in athletes. Katz explains the vascular disease here:
“Because of where the muscles and tendons around Williams’ knee are positioned, they end up compressing the “popliteal artery,” the main one behind the knee, restricting blood flow to the lower leg. It can lead to cramping and calf pain during exercise, per Johns Hopkins Medicine.