sentence2_structure: Bones, cartilage, and ligaments<>make up<>the skeletal system
sentence1: Orthopedic Procedures -- Arthroscopic surgery, repair of ligaments, tendons, cartilage, biopsies, bone grafts and other procedures.
sentence2: Bones, cartilage, and ligaments make up the skeletal system.
question: Bones, cartilage, and what other thing make up the skeletal system?