Hip Osteoarthritis
Labrum Tear
Transient synovitis
Muscle strain
Fracture (could be occult / pathologic / stress)
Tendinitis
Trochanteric bursitis
Slipped capital femoral epiphysis (SCFE)
Lumbar disk disease
Meralgia paresthetica
Osteonecrosis, aseptic necrosis, avascular necrosis
Legg-Calve-Perthes (avascular necrosis of the proximal femoral head)
Aortoiliac vascular occlusive disease
Sacroiliac joint disease
Acute synovitis
Septic arthritis
Metastatic tumor
Herpes zoster
Osteomyelitis
Idiopathic chondrolysis
Psoas abscess
Leukemia
Sickle cell crisis
Primary bone tumor
Further reading
Am Fam Physician. 2014 Jan 1;89(1):27-34. http://www.aafp.org/afp/2014/0101/p27.html