It's too bad to hear about your dog's torn ligament. If your vet said that surgery is not really necessary, perhaps your vet is right. a torn ligament does not always call for surgical correction. the best way to determine if your dog really needs surgery is to go through an 8-week period where activity is carefully restricted and assess whether your dog can re-stabilize the affected joint. The eight week-period is not really the time which is needed for the ligament to heal, rather it is the observation period whether or not your dog can restore stability to the joint. If after the 8-week period you have not observed any improvements, even though how little they may be, surgery may have to be done.
Our prayers for Maggie's speedy recovery:)