Obesity has been linked with the most common hip disorder in children ages nine to 17: slipped capital femoral epiphysis (SCFE). In this study scientists report on the specific Body Mass Index (BMI) for age that puts a child at increased risk for SCFE.
In older children and teens, the head of the femur (thigh bone) is still a cap of cartilage called the epiphysis. There is also a growth plate called the physeal plate. These two features allow for continued bone growth. As the child reaches bone maturity the growth plate closes and the cartilage hardens to form one long bone.
With SCFE there is a separation of the ball of the hip joint from the femur. The force of the child’s body weight puts a shear force across the physeal (growth) plate.
BMI in children is measured according to age in percentiles. Weight above the 95th percentile is overweight or obese. Being in the 95th percentile means the child weighs more than 95 percent of all children the same age. Weight between the 85th and 95th percentiles increases the child’s risk of obesity.
In this study the BMIs of two groups of children with hip pain were compared. One group had SCFE. The other group did not have SCFE. They found that most of the children with SCFE were in the obese range. Most of the children without SCFE were normal weights.
According to the results of this study, BMI can be used to assess risk for SCFE. It’s a simple, safe, and inexpensive test of a child’s level of obesity. Using it on a regular basis can show changes early over time. Since obesity is a modifiable and preventable factor, perhaps the number of cases of SCFE can be reduced in time.