Slipped capital femoral epiphysis is a separation within the thighbone (femur) at its growth plate in the hip joint.

Slipped capital femoral epiphysis usually develops in early adolescence and most commonly affects boys. Obesity is a major risk factor. The cause is not known. However, the disorder may result from a weakening in the growth plate, which can result from injury, hip deformities (coxa profunda), complications due to obesity, inflammation, or changes in levels of hormones in the blood (such as a low thyroid hormone level), which normally occur around puberty. The separation causes the top part of the thighbone to eventually lose its blood supply, decay, and collapse.

The first symptom may be stiffness or mild pain in the hip. However, the pain may seem to come from the knee or thigh. The pain lessens with rest and worsens with walking or moving the hip. Later, a limp develops, followed by hip pain that extends down the inner thigh to the knee. The affected leg is usually twisted outward.

X-rays of the affected hip show slippage or separation of the head of the thighbone from the rest of the bone. Ultrasonography and magnetic resonance imaging (MRI) are also useful, especially if x-rays are normal. Early diagnosis is important because treatment becomes more difficult and gives less satisfactory results later.

Surgery is usually needed to align the separated ends of the thighbone and to fasten them together with metal screws. The hip is immobilized in a cast for several weeks to 2 months.