Findings: Image #1 is a plain film of the hip demonstrating a very subtle region of sclerosis involving the inferior aspect of the femoral neck.

Image #2 is a T1 weighted MR image of the hip, demonstrating a somewhat linear region of decreased signal extending through the femoral neck.

Diagnosis: Insufficiency fracture of the femoral neck.

Discussion: Insufficiency fractures are a result of normal physiologic stresses on abnormal bones. This most often occurs in elderly individuals with osteoporosis, but others, such as those with rheumatoid arthritis or renal osteodystrophy may be affected. In addition, patients on chronic steroid therapy or following irradiation, may also develop insufficiency fractures. When associated with senile osteoporosis, the insufficiency fractures most commonly involve the subcapital region of the femoral neck, but other regions may also fracture.

The plain film findings are often subtle and include vague sclerosis as well as periostitis or buttressing. MRI is highly sensitive for the detection of femoral neck insufficiency fractures, and may be quite helpful when the plain film is nondiagnostic. The fracture is generally visualized as an irregular region of decreased signal intensity on T1 weighted images traversing the femoral neck.

Reference:
Rogers L. Radiology of Skeletal Trauma. Churchill Livingstone, Inc.
New York. 1992;67-69 and 1121-1123.

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