Osteomyellitis is bad disease of bone and takes time to heal some time years. If there is no pus coming out and wound is well healed, then you can get blood investigation like ESR
and CRP. These will test if there is still some pus inside bone. Also if there is pus inside patient will continue to have fever
, night sweat. It would be better to completely pen the bone rather then doing some drill hole ,this procedure is called saucerisation.