( ( ( ( ( Stitches ( ( can not ) ( ( ( make up ) ( for ( the strength ) ) ) ( ( the cartilage ) ( used ( to have ) ) ) ) ) ) , ) so ) ( ( ( ( the ( constant movement ) ) and ) stress ) ( ( ( placed ( on ( the knee ) ) ) ( in ( everyday movement ) ) ) ( ( wear down ) ( the ( damaged cartilage ) ) ) ) ) ) . )
(ROOT (S (S (NP (NNS Stitches)) (VP (MD can) (RB not) (VP (VB make) (PRT (RP up)) (PP (IN for) (NP (DT the) (NN strength))) (NP (NP (DT the) (NN cartilage)) (VP (VBN used) (S (VP (TO to) (VP (VB have))))))))) (, ,) (IN so) (S (NP (NP (DT the) (JJ constant) (NN movement)) (CC and) (NP (NN stress))) (VP (VP (VBD placed) (PP (IN on) (NP (DT the) (NN knee))) (PP (IN in) (NP (JJ everyday) (NN movement)))) (VP (NN wear) (PRT (RP down)) (NP (DT the) (VBN damaged) (NN cartilage))))) (. .)))
Stitches cannot make up for the strength the cartilage used to have, so the constant movement and stress placed on the knee in everyday movement wear down the damaged cartilage.
(ROOT (S (NP (NNS Hagfishes)) (VP (VBP have) (NP (NP (DT a) (NN skull)) (VP (VBN made) (PP (IN of) (NP (NN cartilage)))))) (. .)))