I picked Jane up at 6.30 this evening. It seems they were not going to let her go until they were absolutely sure she had recovered.
It turns out she has torn her cruciate ligament and there is nothing they can do to repair it so she will have to live with that, the consequences of which she is unsure about. They sucked out a lot of junk including some bone so no wonder it was giving her a lot of discomfort. It seems her medial colateral ligament has repaired itself.
She sees the consultant in 6 weeks time and will undergo some physiotherapy in the coming weeks. It's unlikely she will ever play squash again.