SCFE, or slipped capital femoral epiphysis, is a hip condition where the ball at the top of the thighbone slides off the neck of the bone at the growth plate. It’s the most common adolescent hip disorder, affecting roughly 2 to 11 out of every 100,000 children in the United States. Because it involves the growth plate, it only happens in kids and teens who are still growing.
How the Hip Joint Is Affected
Your hip is a ball-and-socket joint. The “ball” is the rounded top of the femur (thighbone), and the “socket” is a cup-shaped part of the pelvis. In a growing child, the ball isn’t yet fused to the rest of the femur. A layer of softer, developing cartilage called the growth plate sits between them, connecting the ball to the neck of the bone.
In SCFE, that growth plate weakens and the ball slips backward and downward off the neck of the femur, like a scoop of ice cream sliding off a cone. The bone itself doesn’t break in the traditional sense. Instead, the connection at this softer cartilage layer gives way. As the ball shifts further backward, the leg naturally rotates outward to avoid pinching inside the joint. This changes how a child walks, which in turn places even more stress on the weakened growth plate and can worsen the slip over time.
Who Gets SCFE
SCFE typically strikes between the ages of about 8 and 16. Boys tend to be affected more than girls and present at a slightly older age, around 13 on average compared to about 12 for girls. Body weight is one of the strongest risk factors. Children with SCFE consistently have higher-than-average BMI, and obesity dramatically increases the chance of both hips being affected. In one study, nearly all patients who developed SCFE in both hips had a BMI at or above the 85th percentile for their age. Children with a BMI at or above the 95th percentile were about five times more likely to have bilateral slips.
Certain hormonal conditions and kidney disease also raise the risk, likely because they interfere with how the growth plate develops and strengthens. But most children diagnosed with SCFE have no underlying endocrine problem at all.
Symptoms and Why Diagnosis Is Tricky
Most kids with SCFE describe pain in the hip, groin, or upper thigh. The pain usually comes on gradually and gets worse with activity. Walking often looks different: the affected leg may turn outward, and the child might limp or lurch their upper body to compensate.
Here’s the tricky part: about 15% of children with SCFE show up complaining of knee pain or lower thigh pain instead of hip pain. Because the hip and knee share nerve pathways, a problem in the hip can feel like it’s coming from the knee. These kids are significantly more likely to be misdiagnosed, sent for unnecessary knee X-rays, and by the time the real problem is found, the slip tends to be more severe. Any adolescent with unexplained knee or thigh pain, especially one who is overweight, should have their hip evaluated.
Stable vs. Unstable Slips
The single most important factor in predicting how serious SCFE will be is whether the slip is stable or unstable. This classification, introduced by Dr. Loder in 1993, is straightforward: if the child can still put weight on the leg (even with crutches), the slip is stable. If they cannot bear weight at all, it’s unstable.
The distinction matters enormously because of a complication called avascular necrosis, where the blood supply to the ball of the femur is disrupted and the bone begins to die. Stable slips carry less than a 10% risk of this happening. Unstable slips carry a 24% to 47% risk. In Loder’s original study, none of the patients with stable slips developed avascular necrosis, while 47% of those with unstable slips did. That gap has held up in research over the following decades.
How It’s Diagnosed
Diagnosis starts with X-rays of the hip taken from two angles: a straight front-to-back view and a “frog-leg” view where the knees are bent outward. Doctors look for several specific signs. One key finding involves drawing a line along the upper edge of the femoral neck. In a normal hip, this line crosses into the ball of the femur. In SCFE, because the ball has slipped, the line misses it entirely. Another sign involves tracing the curved outline where the ball meets the neck on the frog-leg view. Any break or sharp turn in that smooth curve suggests a slip.
These signs can be subtle in early or mild cases, which is one reason SCFE is sometimes missed on initial imaging. When the clinical picture is suspicious but X-rays are inconclusive, a CT scan can reveal fracture lines through the growth plate that plain X-rays might not show.
Surgery Is the Standard Treatment
SCFE is treated surgically, and the goal is to prevent the slip from getting worse. The most common procedure for a stable slip is called in situ pinning: a single screw is placed through the bone and across the growth plate to hold the ball in its current position. This stops the slip where it is without trying to push the ball back into its original place. For stable slips, this approach carries virtually no risk of avascular necrosis.
Unstable slips are more complicated. Regardless of the surgical approach chosen, the risk of avascular necrosis remains significant. A large meta-analysis found that pinning an unstable slip in place results in avascular necrosis about 18.5% of the time. When the surgeon first attempts to gently reposition the bone before pinning, rates are slightly higher, around 23% to 28%. More involved open surgical procedures carry similar risks in the range of 10% to 20%. Another possible complication is cartilage loss in the joint, most often caused by the surgical pin accidentally penetrating into the joint space.
Recovery After Surgery
After pinning, most surgeons take a cautious approach with weight bearing. Children with mild stable slips may be allowed to walk relatively soon, while others are kept on crutches with limited weight on the affected leg for several weeks. There’s ongoing debate among orthopedic surgeons about exactly how quickly full weight bearing should resume. Some allow it early for mild cases without complications, while most prefer a more gradual return. The specifics depend on how severe the slip was and how stable the fixation feels.
Risk to the Other Hip
One of the most important things families need to know is that SCFE can affect both hips. Reported rates of bilateral involvement range from 18% to 50%, and long-term follow-up studies into adulthood have found rates as high as 63% to 66%. Among children who develop SCFE in both hips, about half to 60% already have both hips involved when they’re first diagnosed. For the rest, the second hip typically slips within 18 months of the first.
The risk of a second slip drops sharply as a child’s skeleton matures. Once a specific growth center in the pelvis (the triradiate cartilage) has closed, the chance of the other hip slipping falls to just 4%. Younger children with more growing left to do, and those with obesity, face the highest risk. Whether to preventively pin the unaffected hip remains one of the bigger debates in pediatric orthopedics, but it’s most commonly considered in children who are obese, young, or have hormonal conditions that increase their vulnerability.
Long-Term Outlook
For children with stable SCFE caught early and treated with a single screw, the long-term outlook is generally good. The growth plate eventually closes on its own as the child finishes growing, and many go on to have well-functioning hips into adulthood. The key factors that worsen the prognosis are instability, severe displacement, and delayed diagnosis. More severe slips change the shape of the hip joint permanently, which can lead to stiffness, reduced range of motion, and an increased risk of early arthritis later in life. This is why prompt recognition matters so much, especially in overweight adolescents with any hip, thigh, or knee pain and an unexplained limp.