Mouse was sedated the entire time he was in the hospital, and was given preventive antibiotics to prevent any infection. Only later would the boy realize how lucky he was to meet Marcus and have Blacker as a sponsor. Any other boy would have been sent back to the sewers lame, with only painkillers that wouldn't last him even the first day and with the risk that those newly stitched wounds would become infected with the filth down there.
Few would have survived, so operating on a pooper scooper was a partly useless expense. But Blacker had planned to take Mouse in until the time came for him to turn ten and be able to get out of absolute poverty.