( This ( ( ( is usually ) ( achieved ( by ( fixing ( it ( to ( allow movement ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBZ is) (ADVP (RB usually)) (VP (VBN achieved) (PP (IN by) (S (VP (VBG fixing) (S (NP (PRP it)) (VP (TO to) (VP (VB allow) (NP (NN movement)))))))))) (. .)))
This is usually achieved by fixing it to allow movement.
(ROOT (S (NP (JJ Fixed) (NNS joints)) (VP (VBP do) (RB not) (VP (VB allow) (NP (NP (DT any) (NN movement)) (PP (IN of) (NP (DT the) (NNS bones)))))) (. .)))