Kids who are obese may be more likely to develop a severe hip disorder than children who are not overweight, a UK study suggests.
The disorder, known as slipped capital femoral epiphysis (SCFE), is one of the most common hip problems in children and adolescents. It can lead the ball at the head of the thigh bone to slip backward and often requires surgery to repair. While the condition has long been linked to obesity, which can put extra pressure on bones, research to date hasn’t offered decisive evidence that obesity directly causes SCFE.
For the current study, researchers examined data on weight for more than 597,000 children when they were 5 to 6 years old, with an additional record of weight for nearly 39,500 of these youth at 11 to 12 years old. During an average of seven years of follow-up, 209 children were diagnosed with SCFE.
Compared to kids who were a normal weight at the start of the study, children with severe obesity were almost six times more likely to develop SCFE and youth who were less obese were almost four times more likely to develop SCFE, researchers report in Pediatrics.
And by 11 to 12 years old, youth with severe obesity had 17 times the risk of SCFE that normal weight children had.
“Some doctors, in particular orthopedic surgeons, have long believed that SCFE is linked to childhood obesity, though this has been very difficult to prove,” said lead study author Daniel Perry of the University of Liverpool in the UK.
The current study wasn’t a controlled experiment designed to prove whether or how obesity might directly cause SCFE.
But “the strength of this association is striking,” Perry said by email.
Children and teens are considered obese when their body mass index (BMI) is higher than 95 percent of other youth their same age and sex. They’re considered severely obese when their BMI is higher than 99 percent of other kids.
At the start of the study when kids were about 5.5 years old on average, 12 percent of them were overweight and 9.2 percent were obese.
Among the 3,973 children who were obese at that point, 2,963 (75 percent) remained obese at 11 to 12 years old.
“There are multiple health problems associated with childhood obesity, and we now know that SCFE is one of them,” said Dr Tim Theologis of Oxford University Hospitals in the UK.
“Although this was beyond the scope of this study, it is logical to assume that if obese children were to lose weight, this would reduce their risk of SCFE,” Theologis, who wasn’t involved in the study, said by email.
Obesity may add to the risk of SCFE because the growth plate where the thigh bone meets the hip joint is made of cartilage that’s weaker than bone, noted Dr. Deborah Eastwood of University College London. Rapid growth during pre-teen and teen years coupled with excess weight can damage the hip, leading to pain and reduced range of motion.
“This is the first (of hopefully several studies) that will confirm that obesity is bad for children - in this case bad because it increases the risk of a rare but ‘nasty’ orthopedic condition which could be disabling,” Eastwood, who wasn’t involved in the study, said by email. “Children who are not overweight tend to be more active, fitter and healthier - and this can only be good for you.”