SCFE is characterized by a displacement of the capital femoral epiphysis from the femoral neck through the physeal plate. Sometimes also termed slipped upper femoral epiphysis (SUFE) or physiolysis of the hip, it is one of the most common hip disorders of adolescence, with an overall incidence of 10.8 per 100,000.¹ The average age at the time of diagnosis is 11 to 12 years for girls and 12 to 13.5 years for boys.^1–4 SCFE is more common in males than females, with a ratio of approximately 1.5 to 1, and is more frequent in African Americans and Hispanics.^1,3 Obesity is a significant risk factor in the development of SCFE, as approximately one-half of children who acquire an SCFE have weights at or above the 95th percentile.^5,6 The incidence is increasing with the increasing prevalence of obesity in adolescents.^5,7 About 10% to 20% of children have bilateral slippage at presentation, and another 10% to 20% of patients who present with unilateral disease are diagnosed with a contralateral slip during adolescence.^8,9 Contralateral hip slippage can even be diagnosed after the adolescent period. Among patients with known endocrinopathies, up to 100% can eventually develop bilateral slippage.¹⁰

The two most common features of the presentation of SCFE are pain and altered gait. The classic presentation is that of an obese adolescent without other risk factors and a complaint of nonradiating, dull, aching pain in the hip, groin, thigh, or knee without a history of trauma. However, 15% of patients present with isolated thigh or knee pain.¹¹ Symptoms are generally worse with physical activity and relieved by rest, and may be acute, chronic, or intermittent. SCFE is more likely to be missed at the initial visit if hip pain is absent or thigh pain is present. Table 110-1 summarizes important differential diagnoses to consider for children presenting with hip pain.

SCFE has traditionally been classified based on intensity and duration of symptoms into four patterns of presentation: pre-slip, acute, acute on chronic, and chronic.

Pre-slips refer to those with pain but without discernible displacement of the epiphysis. Radiographs will show a widening of the proximal femoral physis when compared to the asymptomatic hip.

Children with acute slips have symptoms of less than 3 weeks duration. The acute presentation is often associated with trauma. The symptoms are characterized by the onset of severe pain, external rotational deformity and limitation of motion of the hip, shortening, and frequently inability to bear weight. Active motion of the hip is severely limited by muscle spasm, and the patient complains of intense pain with any attempt at passive motion. A joint effusion is present but there is no metaphyseal remodeling. These patients are at risk of further epiphyseal displacement and therefore should immediately be made non–weight-bearing until they receive definitive treatment. This will also provide pain relief.

The acute on chronic presentation occurs when a patient with an extended history of symptoms and signs of chronic SCFE presents with an acute increase in pain and loss of motion of the affected hip. Both a joint effusion and metaphyseal remodeling are present. As with acute SCFE presentations, patients should be made immediately non–weight-bearing.

Chronic SCFE is the most frequent pattern of presentation and is characterized by vague, intermittent symptoms over a protracted period, generally considered to be longer than 3 weeks.

Patients with chronic SCFE generally have limited any strenuous and sporting activities due to discomfort. They often complain of dull pain, often exacerbated by walking or going up stairs, that does not resolve quickly with rest. Patients often complain of knee or thigh pain rather than hip pain. On physical examination, the patient will usually have altered gait. If a unilateral SCFE is present, the patient will have an antalgic gait (pain on weight bearing of the affected side so that the patient takes a quick, short step on the involved side and a long step on the other side). If bilateral SCFEs are present, the patient will have more of a waddling gait. On inspection, the affected leg is in an externally rotated position and may be shortened. Disuse atrophy of the upper thigh and gluteal muscle may be present but can be difficult to appreciate in obese patients. On palpation, there may be tenderness over the hip anteriorly. Despite a complaint of pain to the general area of the knee, there will be no localized tenderness to palpation, and the remainder of the knee examination is normal. Range of motion is decreased primarily on internal rotation, abduction, and flexion but may be painful in all directions. Range of motion is generally normal for adduction. The degree of restriction of range of motion is dependent upon the severity of the slip. When the hip is passively flexed from an extended position, the thigh of the affected limb abducts and externally rotates. This finding is very suggestive of SCFE.¹² Patients who present with chronic SCFE will have no joint effusion but metaphyseal remodeling.

SCFE has also been classified based on biomechanical stability as “stable” or “unstable.”¹³ A slip is stable if walking and weight-bearing are possible with or without crutches. These patients should still be non–weight-bearing until treated. The average duration of symptoms in which stable SCFE presents is 4 to 5 months.⁴ Unstable slips are those in which the child has such severe pain that walking is not possible even with crutches or the epiphysis is displaced from the metaphysis. Patients with unstable slips may have forewarning symptoms such as vague pain in their hips, thighs, or knees for weeks to even months prior to sustaining an unstable SCFE.¹⁴ There is a higher risk of poor outcomes for those with unstable slips.

Lastly, SCFE can be classified by the severity of slippage and graded as mild, moderate, or severe. This correlates with prognosis. A mild slip is one in which the displacement of the epiphysis is less than one-third of the diameter of the femoral neck. A moderate slip is displacement of more than one-third but less than one-half of the diameter of the neck. A severe slip is displacement of more than one-half of the diameter of the neck.

The term SCFE is actually a misnomer because the epiphysis remains in normal position in the acetabulum while the femur distal to the physis (growth plate) displaces, most commonly anterolaterally and superiorly.¹⁵ This displacement of the proximal femoral metaphysis gives the appearance of the epiphysis being displaced posteriorly and inferiorly. The cause of SCFE is the application of stress to the most proximal femur in an amount that exceeds the strength of the capital femoral physis.¹⁶ The underlying etiology of SCFE remains unknown but likely is secondary to multiple factors that result in a weakened physeal plate that is loaded with higher-than-normal shear stress leading to the slippage. Proposed contributing factors include trauma (especially in acute and acute-on-chronic slips), obesity, inflammatory changes that weaken the physeal plate, a history of receiving radiation therapy, genetic predisposition or disorders (e.g., Down and Rubenstein–Taybi syndromes), renal failure, and endocrine and metabolic disorders.