A surgeon can place a bone perforator in contact with a bone, and can hammer on the bone perforator. The hammering can drive teeth on the bone perforator into the bone, thereby creating a perforation in the bone. The surgeon can pry or break the bone along the perforation, can access tissue beneath the bone as needed, and can replace the bone along the perforation. In some examples, the bone perforator is formed as a bendable sheet having teeth in a fixed, single-file pattern, with a hammerable surface opposite the teeth. In other examples, the bone perforator has repositionable teeth.