Slipped Upper Femoral Epiphysis

Often atraumatic or associated with a minor injury. Slipped upper femoral epiphysis is one of the most common adolescent hip disorders and represents a unique type of instability of the proximal femoral growth plate.¹ Four separate clinical groups are seen:

• Pre-slip: wide epiphyseal line without slippage
• Acute form: slippage occurs suddenly, normally spontaneously
• Acute-on-chronic: slippage occurs acutely where there is already existing chronic slip
• Chronic: steadily progressive slippage (commonest form)

• Incidence is 30-60/100,000 children per year.
• Most commonly occurs in boys of 10-17 years of age. Peak age is 13 years for boys and 11.5 years for girls.
• It is the commonest hip disorder in adolescents.
• Left hip is more commonly affected than right; bilateral in 20-40% of cases.²
• Three times as common in boys.³

Risk factors

• Mechanical: local trauma, obesity
• Inflammatory conditions: neglected septic arthritis
• Hypothyroidism, hypopituitarism, growth hormone deficiency, pseudohypoparathyroidism
• Previous radiation of the pelvis, chemotherapy, renal osteodystrophy-induced bone dysplasia

• Discomfort in hip, groin, medial thigh or knee (knee pain is referred from hip joint) during walking; pain accentuated by running, jumping, or pivoting activities.
• Pre-slip: slight discomfort.
• Acute:
  • Severe pain such that child is unable to walk or stand.
  • Alterations in gait, including limp on affected side, external rotation of leg, and trunk shift.
  • Hip motion limited, especially internal rotation and abduction due to pain.
• Acute-on-chronic: pain, limp and altered gait occurring for several months suddenly becomes very painful.
• Chronic:
  • Mild symptoms with child able to walk with altered gait. Significant number of cases report knee pain as only symptom.
  • External rotation of leg during walking. Range of motion of hip shows reduced internal rotation with additional external rotation.
  • When flexed up, hip tends to move in externally rotated position.
  • Mild-to-moderate shortening of affected leg.
  • Atrophy of thigh muscle may be noted.

Other causes of hip pain, e.g.:

• Acute hip fracture
• Perthes disorder
• Acute transient synovitis
• Osteomyelitis
• Septic arthritis

Anteroposterior and 'frog-leg' lateral X-rays show widening of epiphyseal line or displacement of the femoral head.

• Earliest findings include globular swelling of the joint capsule, irregular widening of the epiphyseal line and decalcification of the epiphyseal border of the metaphysis.
• Epiphysis normally extends slightly cephalad to the upper border of the femoral neck.
• Small amounts of slippage can be detected by the epiphyseal edge, becoming flush with the superior border of the neck.
• Sometimes, however, the only evidence of epiphyseal injury is slight widening of the growth plate.

• Associated injuries are common with slipped capital femoral epiphysis; patients should be evaluated for possible pelvic fractures.

• Avoid moving or rotating leg. Patient should not be allowed to walk.
• Provide analgesia and immediate orthopaedic referral if the diagnosis is suspected.
• Patient should be scheduled for surgery immediately.
• Surgical closure of the epiphysis usually by inserting screws percutaneously.⁴
• Corrective osteotomy is usually reserved for treatment of severe deformities after the patient has stopped growing.²

• Chondrolysis (degeneration of the articular cartilage), avascular necrosis of the epiphysis, and long-term effects of altered femoral head anatomy.
• Chondrolysis is seen in 5-8% of slips, and is associated with specific risk factors: African-American race, female gender, screw penetration of articular cartilage, body cast immobilisation, femoral neck osteotomy, and severe slips.
• Avascular necrosis of the epiphysis⁵ occurs in 10-25% of cases, and is associated with attempts to reduce a displaced epiphysis before treatment and with osteotomy of the femoral neck.

• Prognosis depends on initial degree of epiphyseal slippage.
• End result is good to excellent in 94-96% of cases if fragments are displaced by less than one-third of the diameter of the femoral neck.
• With increasing displacement, complications increase and up to 45% of patients have a fair-to-poor surgical result.