Slipped capital femoral epiphysis

Slipped capital femoral epiphysis (SCFE) refers to the posterior and inferior displacement of the femoral head in relation to the femoral neck at the proximal femoral growth plate. It occurs most commonly in adolescent males. While the etiology is not entirely understood, multiple risk factors such as obesity and endocrine disorders have been identified. SCFE may have an acute or insidious onset, with hip pain, limping, and restricted movement of the affected hip. If the patient is unable to walk then the SCFE is considered unstable, which increases the risk of complications such as avascular necrosis. Conventional x-ray confirms the displacement. Surgical fixation of the femoral head is the only treatment.

• Prevalence: Most common hip disorder in adolescents ^[1]
• Peak incidence: : 10–16 years (often occurs during a growth spurt) ^[1]
• Sex: : ♂ > ♀

Epidemiological data refers to the US, unless otherwise specified.

The exact etiology is still unknown. However, there are some risk factors that increase the likelihood of SCFE: ^[2]

• Obesity
• Family history
• Endocrine or hormonal factors (e.g., hypothyroidism; , pituitary tumors, down syndrome, renal osteodystrophy, craniopharyngioma)
• Trauma (e.g., sports-related injury or fall)

• Poor cartilaginous maturation and endochondral ossification in the epiphyseal growth plate leads to unusually wide and unstable proximal femoral epiphyseal growth plate ^[1][3]
• Increased shear force (e.g., due to obesity, trauma) across the growth plate leads to posterior and inferior displacement of femoral epiphysis from the femoral neck ^[1]

To visualize the displacement of the femoral head in slipped capital femoral epiphysis, imagine a scoop of ice cream that slips from its cone.

• Onset
  • Acute
  • Chronic (3 weeks to several months)
  • Acute on chronic (chronic with acute exacerbations)
• Location: bilateral in 20–40% of cases ^[4]
• Symptoms ^[2]
  • Dull pain in the medial thigh, knee , groin, or hip (often left > right)
  • Limping
  • Restricted range of motion
    • Reduced internal rotation and abduction
    • Patients may hold their hip in passive external rotation
    • Drehmann sign positive: external rotation and abduction during passive flexion of the affected hip in supine position ^[5]
• Stability of the physis
  • Stable: able to bear weight on affected hip, with or without crutches
  • Unstable : inability to ambulate and bear weight on affected hip, even with crutches and associated with a high risk of avascular necrosis

• Imaging ^[1][6]
  • Modality
    • AP pelvis x-ray
    • Frog leg lateral view (supine position, flexion of 45° and abduction of 45° in the hip): It allows for better evaluation of both hips, femoral head and neck.
  • Findings
    • Widening of the joint space
    • The femoral head is displaced posteriorly and inferiorly in relation to the femoral neck.
    • Klein line not passing the femoral head: It is a straight line drawn along the superior border of the femoral neck that normally passes through the femoral head.
    • Frog leg projection line not passing the femoral head: It is a line drawn through the center of the epiphysis that normally should pass through the center of the femoral neck.
    • Southwick method (for measurement of the slip angle/severity): refers to the tilt of the femoral neck in relation to the femoral head
    • Rules out underlying medical conditions (e.g., rickets)
    • Determines degree of displacement
• Laboratory tests: to exclude endocrinopathies in patients with an atypical age of onset or short stature

• Avoid weight bearing before stabilization ^[1][6]
• Urgent surgical internal fixation with pinning of the femoral head
• Prophylactic fixation of the contralateral hip

• See “Differential diagnosis of pediatric hip pain.”
• Legg-Calvé-Perthes disease
• Transient synovitis
• Septic arthritis

Snapping hip syndrome ^[7]

• Definition: : snapping of the iliotibial band or gluteus maximus over the greater trochanter (external), or snapping of the iliopsoas tendon over the iliopectineal eminence (internal), typically seen in young athletes and dancers
• Epidemiology
  • Sex: ♀ > ♂
  • Peak incidence: 15–40 years
• Clinical features
  • Sensation of lateral or anterior snapping of the hip (possibly audible), with or without pain
  • Feeling of subluxing hip
  • Reduced or resolved with rest
  • May progress to trochanteric bursitis
• Treatment
  • Physical therapy, rest, ice
  • Injection of local anesthetic
  • If complaints persist: surgical treatment

The differential diagnoses listed here are not exhaustive.

• Avascular necrosis of the femoral head
• Early hip osteoarthritis ^[3]
• Chondrolysis of the hip: rapid degeneration of articular cartilage

We list the most important complications. The selection is not exhaustive.