他穿着短裤，膝盖的伤口已经结痂。He had short trousers and scabby knees.你割破了, 血会凝固、结痂.When you cut yourself , blood clots and forms a scab.这个伤口会疼痛难忍，直到大约10天后结痂才会好些。The area can be very painful until scabs form after about ten days....

“结痂”的英语可以翻译为：scab，[医] escharosis，incrustation ...