My dog Daisy is almost 10 years old and had LP surgery as a young dog for a grade 4 luxating patella. Since that surgery, things have been great.
Last night, we do not know what happened to Daisy. She started to fall over, and drag her hind leg -- the same leg that had surgery way back when. She could not walk and was flailing in pain. She was rushed to the ER vet (and I got stood up at the airport

) where the ER hopsital said that there were no broken bones and that it was likely a soft tissue injury.
We were given Tramadol

and ordered on crate rest

. We have a follow up tomorrow with our reguar vet to see what our next step is.
MY CONCERN: this is the same leg as the LP surgery so I am worried.

Could something be torn? How would I know without an MRI? Should I do an ortho consult or just try the crate rest? She's eating and seems normal but is unable to stand up without dragging the leg behind her like a rubber chicken.
All of her blood work was normal 2 weeks ago.
Any thoughts?