Introduction. Osteonecrosis of the femoral head (ONFH) is an intractable
disease that causes progressive femoral head collapse, severe pain, and gait
disturbance. We report a case of avascular necrosis of the femoral head
following an occult femoral neck stress fracture, which shows that early
diagnosis and treatment are very important. Case report. A 55-year-old woman
presented to our department with a chief complaint of low back pain that
radiated into the left anterolateral thigh for 2 months Her left
anterolateral thigh became progressively more painful over a period of about
2 weeks. No abnormal findings indicative of ONFH or an occult fracture of
the femoral neck were detected by X-ray or computed tomography (CT), but an
occult insufficiency fracture of the left femoral neck was identified on
magnetic resonance imaging (MRI). The diagnosis of femoral neck stress
fracture was delayed, resulting in femoral head necrosis. The fracture was
treated with total hip arthroplasty and the resected femoral head was
subjected to histopathology. Based on the histopathological findings, the
final diagnosis of this case was ONFH with an occult fracture of the left
femoral neck. Clinical symptoms were relieved postoperatively. Conclusion.
In patients presenting with a suspected stress fracture of the femoral neck,
early MRI examination is recommended to avoid femoral head necrosis due to a
delayed diagnosis.