SCFE - slipped capital femoral epiphysis
SCFE is the most common hip disorder in the adolescent age group. It occurs when weakness in the proximal femoral growth plate allows displacement of the capital femoral epiphysis. In actuality the epiphysis doesn’t displace, rather it's the metaphysis that displaces anterior and superior leading to the slipped state.
The weakness of the metaphysis can be caused by a range of factors including stress due to obesity or endocrine disorders such as panhypopituitarism and hypothyroidism, additionally, periods of rapid growth in adolescence can cause undue stress leading to the slip.
Key risk factors for the disease include:
- Puberty
- Obesity
- Endocrine disorders
- Male
- Family history
- Prior radiotherapy
Presence of the above risk factors along with gait with affected leg externally rotated are suggestive of SCFE. Pain may be present in the hip, groin or the knee with or without the ability to weight bear.
Classification of SCFE is as follows:
- Based on symptom duration
- Acute - prodromal symptoms lasting < 3 weeks prior to an acute fracture like event
- Chronic - symptoms lasting >3 weeks
- Acute-on-chronic - symptoms lasting >3 weeks with sudden onset of increased pain and irritation
- Based on weight bearing ability
- Stable - can bear weight with or without support (90% of cases)
- Unstable - unable to bear weight
The latter classification is the most widely used, those with unstable form are more at risk of avascular necrosis.
Physical examination and labs of patients with suspected SCFE should include hormone tests, weight measurements, observation of hip range of movement (obligatory external rotation is present with the hip joint flexed). Passive and active flexion of the hip should be conducted, the affected hip tends to go into external rotation during flexion with a rested range of movement. The patients walk will have a typical external rotation to it.
The XR is a key diagnostic tool, Klein lines are drawn along the superior cortex of the femoral neck, where it should intersect with the epiphysis. An abnormal klein line does not
intersect as the femoral neck has moved proximally and anteriorly relative to the epiphysis. A frog-leg XR should also be done.