hmmmm usually it is the one they were lifting that is bothering them not the other - the other one is affected as well because more weight is shifted on to the other one not lifted and eventually that one not lifted gets worse if the other one is not corrected - did a board certified orthopedic do this surgery or a regular vet
My girl has LP 4 in both back legs and permanently out and she hurt her acl and thankfully is doing fine now. She had xrays on both back legs and her patellas cannot be manipulated back into place at all. She only lifted the leg that was hurt not the other. For peace of mind I would call an orthopedic and honestly if the other one has to be done I would go to a bc orthopedic -- i am not feeling comfortable with the info you were given but obviously there is nothing you can do at this point and you will have to wait it out but if it heals up and he is still lifting the other leg I would not be very happy if i were you
i just really hope the vet did not screw up and do the wrong leg then back tracking from his mistake as that is why they mark human bodies and ask several times before surgery like was done on my achilles tendon before surgery as mistakes have happened -this is not sitting well with me