I'm assuming that this is 480 sq cm. As such 480 - 20 = 460. And since the debridement went TO the bone and did not INCLUDE the bone. In this scenario you would bill codes
11043 x 1 unit (Debridement, muscle and/or fascia (includes epidermis, dermis, and subcutaneous tissue, if performed); first 20 sq cm or less) X 1 unit and
11046 x 23 units (Debridement, muscle and/or fascia (includes epidermis, dermis, and subcutaneous tissue, if performed); each additional 20 sq cm, or part thereof (List separately in addition to code for primary procedure)
No modifier is needed for the 11046 because you cannot bill it by itself. You must have it's parent code with it. Whether you list it 23 times or on a single line with 23 units is carrier specific.
Hope this helps.