Hair loss

Question
My 6 month old Bulldog recently hurt his knee and was diagnosed with luxating patela,no surgery has been performed just rest but he has now got a bald patch about as big as a finger nail on the exact place his injury was i.e his knee cap and another patch is just starting just below could this be to do with the injury as he never suffered hair loss before the accident if so will it disappear or could we treat it with anything to help it grow again.  
    thank You

Answer
Just to be on the safe side, I would have your vet do a skin scraping to make sure it isn't mange which could be brought on by the stress of an injury like this. If there's no sign of mites, then chances are it's nothing serious and the hair will grow back.