The condition is also categorised as:

• • Stable (90% of cases): the patient is able to walk.[1]

  • Unstable (10% of cases): the patient is unable to walk (even with crutches).

Diagnosis is often delayed - and this is associated with a worse prognosis.[2] Although surgery remains the standard treatment, the management of SCFE remains controversial - a Cochrane review is currently assessing the outcome of surgical and non-operative treatments.[3]

Epidemiology

• • The incidence is 10/100,000 children per year.[4]

  • Most commonly it 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 most common hip disorder in adolescents.

  • The left hip is more commonly affected than the right; it is bilateral in 20-40% of cases.

  • It is three times as common in boys.[5]

Risk factors

• • Mechanical: local trauma, obesity.

  • Inflammatory conditions: neglected septic arthritis.

  • Hypothyroidism, hypopituitarism, growth hormone deficiency, pseudohypoparathyroidism, vitamin D deficiency.

  • Previous radiation of the pelvis, chemotherapy, renal osteodystrophy-induced bone dysplasia.

Presentation

• • Discomfort in the hip, groin, medial thigh or knee (knee pain is referred from the hip joint) during walking; pain is accentuated by running, jumping, or pivoting activities.

  • Pre-slip: slight discomfort.

  • Acute:

    • • Severe pain such that the child is unable to walk or stand.

      • Alterations in gait, including a limp on the affected side, external rotation of the leg, and trunk shift.

      • Hip motion is limited, especially internal rotation and abduction, due to pain.

  • Acute-on-chronic: pain, limp and altered gait occurring for several months, suddenly becoming very painful.

  • Chronic:

    • • Mild symptoms with the child able to walk with altered gait. In a significant number of cases knee pain is reported as the only symptom.

      • External rotation of the leg during walking. Range of motion of the hip shows reduced internal rotation with additional external rotation.

      • When flexed up, the hip tends to move in an externally rotated position.

      • Mild-to-moderate shortening of the affected leg.

      • Atrophy of the thigh muscle may be noted.

Differential diagnosis

Other causes of hip pain - for example:

• Acute hip fracture

• Perthes' disease

  • Acute transient synovitis

• Osteomyelitis

• Septic arthritis

Investigations

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 diseases

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

Management

• • Avoid moving or rotating the leg. The patient should not be allowed to walk.

  • Provide analgesia and immediate orthopaedic referral if the diagnosis is suspected.

  • The patient should be scheduled for surgery immediately.

  • Surgical closure of the epiphysis, usually by inserting screws percutaneously.[6]

  • Corrective osteotomy is usually reserved for treatment of severe deformities after the patient has stopped growing.

Complications

• • 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 epiphysis 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.[7]

Prognosis

• • The prognosis depends on the initial degree of epiphyseal slippage and prompt recognition by the general practitioner.

  • The 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.