Correct me if I'm wrong OP, but presumably you run in the city (IE on pavements), with reasonably thick shoes, and you don't run on your toes?
I damaged my knee doing the above, and couldn't run for a while. Learn to run on your toes, with thin shoes, and try to do so on grass. The 40 KG backpack is a very bad idea, the extra weight will just be more strain on your joints, even if you aren't running as far.
You may also want to consider taking glucosamine hydrochloride, you can buy it in Holland and Barrett, I found it help a lot in helping my knee get better
EDIT: This guy speaks a lot of sense
I damaged my knee doing the above, and couldn't run for a while. Learn to run on your toes, with thin shoes, and try to do so on grass. The 40 KG backpack is a very bad idea, the extra weight will just be more strain on your joints, even if you aren't running as far.
You may also want to consider taking glucosamine hydrochloride, you can buy it in Holland and Barrett, I found it help a lot in helping my knee get better
EDIT: This guy speaks a lot of sense
RamirezDoEverything said:Swim. Swim like a fucking fish. Very easy on your joints, and really gets your cardio going.
I was out last track season due to ankle injuries, pool keeps you close to where you want to be for cross counrty.