That if idepends what she enjoys. Repeat radiography may shed light into the stability of the condition. It is essential that and slippage of the growth plate is prevented, but if this is not the issue then swimming and other Non-weight bearing exercise should be ok (?? not sure about breaststroke). If her hip joint survives intact then she can always have a lengthening proceedure when she is about 19-20yrs with external fixation. I have seen one client lengthen his leg 10cm over a year with this approach. He then rehab'd extensively for 12 months and is now back skiing and snowboarding with the best of them.