"A&E doctor missed ruptured ACL"

I flew back from Verbier after damaging my knee on the 9th January and went to A&E at Ipswich hospital to have it looked at. The hospital staff were lovely and great so after the usual hour or so wait I was seen to by a junior doctor. Whilst they seemed friendly and approachable they failed to diagnose a completely ruptured ACL which I had later confirmed by MRI after a private consultation. I also had some tearing of the meniscus. The doctor did not offer a conclusive diagnosis other than saying there may have been some ligament damage. I was told to 'walk it off' and come back later if things didn't improve. Whilst I appreciate that these things do happen sometimes I remain surprised that such a diagnosis could easily have been missed.