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?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.