Differential Diagnosis
- Hip dislocation
- Hip fracture—subcapital
- Hip fracture—intertrochanteric
- Osteolytic lesion of the hip
- Pelvic fracture
Physical Examination
On physical examination, the patient has a temperature of 98.4°F (37°C), a pulse rate of 100 beats/min, a respiration rate of 20 breaths/min, a blood pressure of 108/72 mm Hg, and an oxygen saturation of 99% on room air. He is alert and oriented, not in acute distress, and is breathing comfortably. The boy’s pelvis is stable upon palpation. He has pain upon palpation of the left knee and upon passive movement of the left hip through the range of motion. He has no leg-length discrepancy. He has no history of fractures, and he takes no prescribed medications
Diagnosis
An x-ray is obtained (Figure 2) that shows a left-sided slipped subcapital femoral epiphysis (SCFE).
Learnings
SCFE is the most common hip condition in children between the ages of 9 and 16 years, with a prevalence of 10.8 cases per 100,000 children. It most commonly occurs in males, blacks, and Hispanics. SCFE usually occurs during the adolescent growth spurt and is often associated with obesity, but it can have an endocrinologic etiology. SCFE is defined as a slippage (usually posterior and inferior) of the femoral head (femoral epiphysis) relative to the femoral neck (metaphysis) that occurs through the epiphyseal plate (the growth plate). SCFE occurs bilaterally in 18% to 50% of cases.
SCFE can be either stable or unstable. In the stable type, which occurs in 90% of cases, the patient can ambulate, even with a limp. In the unstable type, the patient cannot ambulate or bear any weight at all on the affected leg. Unstable SCFE has a worse prognosis and a higher risk of complications than stable SCFE does, resulting in osteonecrosis in 20% to 50% of cases and in avascular necrosis in 60%.
What to Look For
Inquire about the mechanism of injury; the symptoms typically begin gradually and rarely occur because of trauma. Patients typically have pain localized to the hip but may report pain only at the groin, medial thigh, or knee. In patients younger than 10 years, check for the presence of these risk factors:
- Endocrine or metabolic abnormalities, including
- Hypothyroidism
- Panhypopituitarism
- Renal rickets
- Hypogonadism
- Growth hormone abnormalities
- Obesity
- Specific demographic characteristics: male, black, Pacific
- Islander
- History of previous SCFE; there is a significant risk for a second occurrence
On physical examination, do the following:
- Document the patient’s general appearance, position, and ability to ambulate.
- Inspect and palpate for skin changes such as erythema, ecchymosis, abrasions, lacerations, fluctuance, necrosis, and crepitus.
- Determine the location of pain.
- Determine exacerbators of pain, such as movement through the range of motion.
- Look for shortening of the affected leg.
- Check for swelling over the hip.
- Watch to see whether the patient involuntarily rotates the hip externally when you flex the hip.
- Watch for limited internal rotation of the hip.
Obtain the following x-rays: anteroposterior views of the hip and pelvis (to look for bilateral SCFE and to compare hips) and frog-leg views. Most patients with SCFE will be transferred to an emergency department because of the following indications:
The possibility of a hip fracture or SCFE that is not evident on x-rays
- An inability to exclude septic arthritis
- The presence of intractable pain
- The presence of unstable SCFE