You need to work out whether the contracture is due to musle shortening or due to spasticity. If spasticity is the issue then Botulinum toxin would help, followed by serial casting for a couple of weeks, then scotchwrap splints, stretches and eccentric and concentric work. If the muscle has adaptively shortened then Botulinum toxin probably won't helpand serial casting may be the way to go, followed by scotchwrap etc. Keep an eye on gastroc length as well. .....oh .. Make sure there is no HTO before you immobilise the joint though!