Imaging Case of the Week 105

The following pelvic x-ray is from a 12 year old who has experienced left knee pain for the past few weeks. What can you notice in the x-ray?

pelvic x-ray

[peekaboo_link name=”Answer”]Answer[/peekaboo_link] [peekaboo_content name=”Answer”]

The pelvic x-ray shows a left slipped capital femoral epiphysis (SCFE) and Klein’s line is abnormal on the left.

A normal Klein’s line is when a line drawn along the superior border of the femoral neck intersects with the femoral head. In SCFE, this line does not intersect with the femoral head.



  • Capital femoral epiphysis stays in the acetabulum and the neck displaces anteriorly and externally rotates.
  • Most common hip disorder affecting adolescents.
  • Male to female ratio is 3:2
  • Bilateral in 17-50% of cases (important to look at the unaffected hip when the pelvic x-ray is obtained in the ED)
  • Increased BMI is the single greatest risk factor
  • Non-obese children under 10 with SCFE need work up for endocrine issues (hypothyroidism/CRF)
  • Groin and thigh pain are the common presenting symptoms. 1 in 4 can present as knee pain.
  • Imaging should include AP and Frog leg lateral of both hips. Lateral view identifies the slip when it is subtle. Plain x-ray features take time to manifest. If the condition is strongly suspected, MRI is the modality of choice when the x-ray appears normal.
  • All patients will need urgent referral to the specialist.

Thanks to Dr. Sani Haxdy for the image.