Any pain or disorder within in the musculoskeletal system of a child is handled by a pediatric rheumatologist. The muscles, tendons, joints, and bones make up the musculoskeletal system. Some conditions that a pediatric rheumatologist may work with include arthritis, joint swelling, an inflammatory disease of some organs, pain complaints, weakness within the musculoskeletal system, or even loss of function within the musculoskeletal system. This type of physician works closely with other specialties in order to create the correct diagnoses and best possible treatment plan for a patient.