Slipped Upper Femoral Epiphysis

Background

• One of the most common adolescent hip problems (around 10/100,000 children per year)
  • The epiphysis usually slips posteriorly relative to the diaphysis of the femur
• Most common in boys and occurs usually around the growth spurt in adolescence (mean age 13)
  • More common in overweight children; left hip slightly more prevalent
  • Whilst weight and mechanical factors (as well as others e.g. hypothyroidism; hypopituitarism; radiation treatment) may play a role, SUFE represents an underlying instability of the proximal growth plate- the exact cause of which is unknown

Classification

• The most important classification is whether the joint is
  • Stable (90%) i.e. the patient is still able to weight bear (function relatively unimpaired)
  • Unstable (10%) the patient is unable to weight bear- requires urgent management
• Other classifications include
  • time-based i.e. acute (symptoms for < 3 weeks); chronic and acute on chronic
  • Southwick angle classification (measurement of the difference between both hips in the femoral head-shaft angle on the frog radiograph)
    • Mild <30°; Moderate 30-50° and severe >50°
  • Grading by degree of slippage
    • I (Up to a third); II (up to a half); III (more than half)

Presentation

• Most commonly presents with hip and/or groin pain
  • Often an acute event but may present but can have had mild symptoms preceding this
  • Can present as radiated knee pain
  • Worse on movement/weight bearing
  • May cause antalgic gait
  • May limit hip movement- particularly internal rotation and abduction (indeed the leg may rest in external rotation/adduction)
• Differential
  • Perthes disease
  • Septic arthritis
  • Developmental dysplasia
  • Synovitis

Investigation

• X-rays
  • An x-ray of the pelvis will usually detect a SUFE
    • Trethowan’s sign
      • Klein’s line (the line drawn up the lateral edge of the neck of the femur) should intersect the femoral head. It fails to do so in SUFE due to slip.
    • You may also see widening of the growth plate (epiphysiolysis) and blurring of the proximal femoral metaphysis (overlapping of the metaphysis and displaced epiphysis)
• Occasionally, where diagnosis is in doubt, a CT or MRI may help confirm the diagnosis

Management

• Surgical management of the affected side
  • Percutaneous fixation with cannulated screw(s)
• There is some controversy as to whether to fix the other side also (bilateral in up to 20% of cases)- currently not recommended
• Without fixation, particularly in unstable cases, there is a risk of osteoarthritis; chondrolysis (breakdown of cartilage and subsequent bony degeration/damage) and avascular necrosis of the femoral head