Acute rheumatic fever
Developmental dysplasia of hip
Femur fracture
Juvenile idiopathic arthritis
Legg-Calve-Perthes disease
Septic arthritis of the hip (peds)
Lyme disease arthritis
Slipped capital femoral epiphysis
Transient (toxic) synovitis
Osteosarcoma
Lyme disease arthritis
Developmental dysplasia
Fracture
Toddler's fracture
Tillaux fracture, adolescent
Neoplasm:
Leukemia
Ewings
Osteogenic sarcoma
Metastatic neuroblastoma
Osteomyelitis
Myositis
Other:
Appendicitis
Meningitis
Epidural abscess (spinal)
Toddler's fracture
Tillaux fracture, adolescent
Leukemia
Ewings
Osteogenic sarcoma
Metastatic neuroblastoma
Appendicitis
Meningitis
Epidural abscess (spinal)
Limp 
Acute rheumatic fever
Hirudins
Developmental dysplasia of hip
Tdap
Femur fracture
CURB-65
Juvenile idiopathic arthritis