im pretty sure she didn't have a cyst but i will ask orthopedic and see if they could do another ultrasound of the hip and see if there is one
Draining is different from a cyst removal in case a cyst existed and which seems very probable.
and took antibiotics for 6 weeks after the hip was drained and washed
she had the hip drained when she was 7..
The question is not clear. From whatever information you have given here,probably she had an infected cyst in the hip which was not removed before performing the knee surgery.
for got to add she wasn't doing anything when she injured her knee her leg gave out on her