The information here is written for meat rabbits but is applicable to pets.
It is best to place 'drywall' in his cage for him to stand on. Yes, yes ...drywall, the stuff you put on walls of a house. Drywall is "Gypsum" also known as 'Hydrated Calcium Sulfate'. Gypsum is a mineral and will not harm the rabbits, instead they get calcium when eaten.
What Gypsum (drywall) does is draw out any moisture and infection the rabbit might get from standing on the wire. It also acts a cushion to help ease the weight of the rabbit on the wire.
(Drywall is very heavy and comes in 4x8 foot sheets. you could break it up and bag it to carry home in your car)
You could use Cardboard from cardboard boxes if getting drywall is not possible. Cardboard will not harm the rabbits if they eat it either.
Even the paper from the feed bags is better then nothing.
Some causes of Sore Hock:
Floor wire the gage of wire is too small. The wire is saggy or loose, poor support, dirty, rusty.
Fungus usually shows up this time of the year.... Front feet more then back feet
Why? No one really knows.
Humidity also causes sore hocks.
Staph infection, as soon as the skin is broken or there is a sore spot there is a chance to get Staph, Staph is everywhere!!! With properly administered antibiotics along with extreme sanitation and husbandry, you can get Staph under control.
Sore hocks is common in very fine boned animals. The skinnier the foot the worse it will get, if it isn't as big as the width of your thumb, then you will have a problem (at least a reasonably substantial thumb) Selection has allot to do with it.