I would say its firstly a police matter, a hit and run so report it, take photos of the road and of course of any injury etc.
When steve got knocked over, we used our house insurance, and then last time, we used a specialist cycle insurer to make a claim, although maybe the driver was not insured or even had a stolen car, that's why they drove off possibly?
With us humans you can usually see the injury but with cycles the bikes tend to fall apart later due to stress cracks. Steve's bike fell apart quite a while after one of the times he was knocked off, although, his injuries although they have never been that bad. I too hate him cycling but that's how he gets to work etc...I just try not to think about it. Steves last injury was caused by him getting pushed into the tram line in Edinburgh but got nothing re compensation, even though his bike was badly damaged, all his clothing and hat needed replacing and he was very shook up and badly bruised....we did go to A&E but the council refused to take responsibility, even though the same night a girl got knocked over in a similar incident and made the papers!
Hope its a good and quick recovery and you at least get some compensation
His injury sounds complicated, he will need time to recover due to possible infection, let alone the damage its caused.