“This case presents a child with an insidious onset of pain and mild limitation of range of motion of one hip joint. The case suggests involvement of the femoroacetabular joint, and all of the listed options can affect this joint.
Idiopathic osteonecrosis of the hip (Legg-Calvé-Perthes disease) occurs most commonly in children at 2–12 years of age and has a male predominance. Symptom onset is insidious, as in this case, with symptom severity and functional limitations dependent on the level of disease progression.
Slipped capital femoral epiphysis occurs much more commonly in adolescents.
Transient synovitis and septic arthritis have a more acute onset, and typically cause fever.
Osteoarthritis typically occurs in older adults.” ABFM
Reference
Evaluation of the patient with hip pain. Am Fam Physician 2014;89(1):27-34