( ( The ( joints exhibit ) ) ( ( flexion ( ( ( contractures , ) especially ) ( the ( ( knees and ) elbows ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNS joints) (NN exhibit)) (VP (VBP flexion) (NP (NP (NNS contractures)) (, ,) (RB especially) (NP (DT the) (NNS knees) (CC and) (NNS elbows)))) (. .)))
The joints exhibit flexion contractures, especially the knees and elbows.
(ROOT (S (NP (NNS Knees) (CC and) (NNS elbows)) (VP (VBP are) (NP (NP (NNS examples)) (PP (IN of) (NP (NP (DT the) (NNS joints)) (PP (IN of) (NP (DT the) (JJ skeletal) (NN system))))))) (. .)))