Tested and working. Add at the start of the script:

local dismember_value = 10000 -- Dismembered points value
local fracture_value = 7000 -- Fracture points value

And overwrite original function with:

local function get_fitness()
   tori_score = math.floor(get_player_info(1).injury)
   uke_score = math.floor(get_player_info(0).injury)
   for i = 0,19 do
        if (get_joint_dismember(0,i)) then
            uke_score = uke_score + dismember_value
        elseif (get_joint_fracture(0,i)) then
            uke_score = uke_score + fracture_value
        end
        if (get_joint_dismember(1,i)) then
            tori_score = tori_score + dismember_value
        elseif (get_joint_fracture(1,i)) then
            tori_score = tori_score + fracture_value
        end
   end
   return (tori_score) - (uke_score)
end