Slipped Capital Femoral Epiphysis is a hip disorder that affects adolescents, most often between 12 and 15 yr of age, and involves the displacement of the CFE from the metaphysis through the zone of hypertrophy layer of the physeal plate.
SCFE may be classified temporally, according to onset of symptoms (acute, chronic, acute-on-chronic); functionally, according to patient’s ability to bear weight (stable or unstable); or morphologically, as the extent of displacement of the femoral epiphysis relative to the neck (mild, moderate, or severe), as estimated by measurement on radiographic or CT images.
An acute SCFE has been characterized as one occurring in a patient with prodromal symptoms for ?3 wk and should be distinguished from a purely traumatic separation of the epiphysis in a previously normal hip . The patient with an acute slip will usually have some prodromal pain in the groin, thigh, or knee and will usually report a relatively minor injury (a twist or fall) that normally is not as sufficiently violent as to produce an acute fracture of this severity.
Chronic SCFE is the most frequent form of presentation. Typically, an adolescent presents with a few-month history of vague groin, upper thigh, or lower thigh pain and a limp.
The children with acute-on-chronic SCFE may have features of both ends of the spectrum. Prodromal symptoms have been present for >3 wk with a sudden exacerbation of pain.
The stability classification separates patients based on their ability to ambulate and is more useful in predicting prognosis and establishing a treatment plan. The SCFE is considered “stable” when the child is able to walk with or without crutches. A child with an “unstable” SCFE is unable to walk with or without crutches. Patients with unstable SCFEs have a much higher prevalence of osteonecrosis (up to 50%) compared to those with stable SCFEs (nearly 0%). This is most likely due to the vascular injury caused at the time of initial displacement.
Mechanical factors created by relative or true femoral neck retroversion, the orientation of the capital epiphysis and the physis on the femoral neck, and alteration of the mechanical strength of the physis, periosteum, and the perichondral ring during adolescence have all been thought to play a role in the etiology of a slipped epiphysis.
Obese children often have retroverted femoral necks that are directed more posteriorly than those of other children. Physiologic forces at the proximal femur generated by normal activities in obese patients can be of adequate magnitude to cause physeal fatigue.
Patients with SCFE usually present with complaints of pain in the affected hip or groin, a change in hip range of motion, and a gait abnormality. Infrequently the patient will complain only of medial knee pain that may be referred to the knee via the obturator and femoral nerves.
The symptoms and physical findings vary according to whether the symptoms are chronic, acute-on-chronic, or acute; whether the slip is stable or unstable; with the severity of the resultant deformity; and with the coexistence of the complications of osteonecrosis or chondrolysis.
In stable, chronic SCFE, the patient describes intermittent pain in the groin, the medial thigh, or the anterior suprapatellar region of the knee. The pain is typically described as dull and vague and is exacerbated by physical activity such as running or sports. The onset of pain may be of several weeks’ or several months’ duration. The patient remains ambulatory, but does show an antalgic gait with associated limp. Physical examination of the affected hip reveals a restriction of internal rotation, abduction, and flexion. Commonly, the examiner will note that as the affected hip is flexed, the thigh tends to rotate into progressively more external rotation and that flexion is limited.
Patients presenting with either unstable acute or acute-on-chronic slipped epiphysis will characteristically report the sudden onset of severe, fracture-like pain in the affected hip region, usually as the result of a relatively minor fall or twisting injury. The acute form manifests by the sudden onset of severe pain and hip dysfunction in a patient who was previously asymptomatic. Physical examination demonstrates the affected limb externally rotated and shortened with the patient refusing to bear weight.
Since approximately 25% of patients will have evidence of contralateral slip on initial presentation, the contralateral hip must always be carefully assessed both clinically and radiographically by the treating physician.