I'm a physician and inject steroids all the time for inflammation. Most likely the pain and discomfort Percy is feeling is likely from inflammation- the shot then should help Percy. Realize that while cortisone directly decreases inflammation, it does not heal any possible structural damage (that's what the surgery is for). From what I have heard recently, Percy has gotten follow up MRI's and there has been no recurrent structural damage to the hip. It appears that Percy is feeling pain and may have limited range of motion simply because of an exaggerated inflammatory response to overworking the healing joint during the Vikings game. The cortisone should help that. A cortisone shot like this could start working right away, ie in a day or two, so depending on how well he reacts to it, it's theoretically possible he could play tonight. On the other hand, it usually takes a week or two to really work (or it might not work at all sometimes), so he likely he will need some more time.