Background: Simultaneous fracture of bilateral femoral necks is a rare case. The femoral neck is a key position of stress on the upper and lower limbs. The femoral head necrosis may be caused by the injury, which is often paid close attention to by trauma surgeon. Fractures due to trauma are categorized as fatigue fractures, and fractures due to pathological factors such as vitamin D deficiency, hyperparathyroidism and chronic renal failure are categorized as dysfunctional fractures Case Presentation: This case described a 30-year-old young male patient with bilateral femoral neck fractures after a short jog. MRI be diagnosed as Garden I type; CT showed mild hip osteoporosis; Laboratory index showed vitamin D deficiency and other performance are normal. He had a history of chronic ankle instability due to the right ankle sprain. Under the guidance and advice of doctors, the fracture achieved recovery after conservative treatment.
Conclusion:The young adult caused by low-energy occult bilateral femoral neck fracture in the early diagnosis is not obvious. Femoral neck fracture in the early X-ray slice is difficult to determine and easy to be misdiagnosed as synovitis of the hip or traumatic arthritis, so that the clinical intervention time was delayed. To avoid fracture displacement and femoral head necrosis, the patient of femoral neck mild fracture requires complete non-weight bearing for 8-12 weeks and part weight bearing for 4-6 weeks; In order to prevent osteomalacia, more severe osteoporosis and abnormal bone metabolism causing convulsions or epilepsy, punctual vitamin D supplementation and reasonable exposure to sunlight is considerable. Timely and effective surgical intervention is necessary for the complete and displaced fractures. CT, MRI, laboratory examination and comprehensive inquiry are helpful to diagnose and eliminate misdiagnosis. Diseases that affect metabolic processes, such as smoking, long-term stay up and severe fatty liver, can be also result in to bilateral femoral neck fractures.