What is slipped capital femoral epiphysis?
Slipped capital femoral epiphysis (SCFE) is a fracture through the growth plate in which the femoral head shifts relative to the femoral neck. Children describe pain in the hip, thigh or knee. Severe pain can appear suddenly (acute), or it can be milder and last longer (chronic). Likewise, the slip can be mild, in which case children can still walk, or more severe, in which case they are no longer able to walk. The slip usually occurs during the adolescent growth spurt, with increased frequency in children who are overweight and those more heavily involved in jumping sports. Because the upper end of the femur in children is structured so that the growth plate lies fairly vertically relative to the ground, it is exposed to large shearing forces. Another significant factor contributing to slippage is hormonal imbalance, when there is an unfavourable ratio between hormones that promote growth and those that influence maturation of the growth plate. Slipped capital femoral epiphysis is somewhat more common in boys, and in 25% of children it occurs in both hips at the same time. In children during the pubertal growth spurt, sudden and severe hip pain, restricted movement, or inability to walk should raise suspicion of SCFE, which requires urgent assessment by a paediatric orthopaedic specialist. This is because SCFE can have catastrophic consequences for a child’s hip – it is a true emergency in paediatric orthopaedics. In fact, the most important step is to suspect the slip, obtain X-rays and examine them carefully.
How is slipped capital femoral epiphysis diagnosed?
Following a discussion in the clinic and a clinical examination of the child, SCFE can be suspected. Children describe intense pain in the hip, thigh or knee that appeared suddenly, usually after some activity. The pain can be so severe that the child limps or is even unable to walk. In the chronic form of the slip, the pain is not sudden or markedly severe; instead, children complain of milder pain and discomfort in the hip or thigh down to the knee, and walk with the foot turned outward. Children with a slip do not have a raised body temperature and are otherwise in good general condition. During the clinical examination, the child should lie down on the examination table and hip range of motion should be checked. Hip flexion is altered – the knee "drifts outward" – while internal rotation of the hip is extremely painful. It is a longstanding rule in paediatric orthopaedics that the hips should be examined in every case of knee pain. The basic diagnostic work-up is an X-ray of the hips in two views, on which the displacement of the femoral head relative to the neck is assessed. Sometimes, in milder and chronic slips, X-ray is not sufficient and an MRI is needed. Other conditions that can cause similar hip complaints at onset include transient synovitis of the hip, septic arthritis of the hip, a stress fracture of the femoral neck, or juvenile idiopathic arthritis of the hip.
How is slipped capital femoral epiphysis treated?
Slipped capital femoral epiphysis is always treated surgically, with stabilisation/fixation of the displaced femoral head using wires or a screw. After surgery, the child should walk with reduced weight-bearing on forearm crutches for 6 weeks. Surgery should be performed as soon as possible to avoid further displacement of the femoral head. With greater displacement of the femoral head, the risk increases that the blood vessels supplying the head will be torn, cutting off its blood supply and gradually leading to avascular necrosis (infarction). This is a severe consequence of SCFE that causes significant pain and is treated with hip replacement surgery. Milder degrees of SCFE have a good prognosis after surgery, as the bone in the neck can remodel so that the hip regains a fully healthy shape. Unfortunately, even after successful surgery, the hip sometimes remains altered and, over time, has a higher chance of developing secondary osteoarthritis – wear of the joint cartilage.
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