(From the September 2015 Issue of PediatricsOnline)
Surgeons at Nationwide Children's Hospital have found that hip dysplasia appears to be associated with bladder exstrophy, a rare congenital defect in which the lower abdomen is exposed and the bladder and bony pelvis are malformed.
Their study, published in the Journal of Pediatric Orthopaedics, raises the question of whether exstrophy and hip dysplasia occur together naturally, or if the procedure that's regarded as the best way to close the bladder and abdomen is causing hip instability.
"Historically, we've believed that osteotomies have no major effect on long-term gait or movement, and that they are relatively safe to do," says V. Rama Jayanthi, MD, chief of Urology at Nationwide Children’s and an author of the study.
Kevin Klingele, MD, chief of Orthopaedics at Nationwide Children’s and senior author of the study, performs osteotomies on exstrophy patients, then Dr. Jayanthi closes the bladder and abdomen. They've done this as a team for 15 years. It's the same procedure used around the world.
Over that time, Klingele began to notice that the patients seemed to have hip dysplasia more often than other babies. "We looked at 20 years of practice and it appears to confirm our anecdotal belief," he says.
Bladder exstrophy is seen only in about two of 100,000 live births. In order to determine the association with hip dysplasia, the researchers reviewed two decades of Nationwide Children's records.
They identified 38 males and 28 females who were born with exstrophies and also had hip images in their records. X-rays showed that 11 patients, or 16 percent of the total, had developmental hip dysplasia—more than would be expected if they were random occurrences.
The x-rays were taken of some patients at birth but not until adolescence or as late as age 22 in others. Whether all the dysplasias existed at birth or some only appeared later is not known.
The researchers recommend doctors look for hip dysplasia in all exstrophy cases. If found at birth, there is an opportunity to address both conditions during the same early surgery.
"The general rule of thumb is if you have an unstable hip at birth, the earlier the hip is stabilized and in the socket, the better the remodeling potential and the better the long term growth and development of that hip," Klingele says. "So if you know early, you can intervene early."
"If the hip problems arrive later, we'll need to determine whether the exstrophy surgery or something else is causing dysplasia," Klingele says.
The possibility that performing the osteotemy causes the hip problems is troubling.
"The data would suggest you're more likely to get a good closure with the osteotomy," Dr. Jayanthi says. "You're really doing everything you can to minimize tension on the closure."
All exstrophy patients will need more surgery as they age to try to gain bladder control. If this closure fails, "It's a bad complication," Jayanthi says. "It increases the number of surgeries for the patient and reduces the long-term outcomes."
In addition to reducing the risk of a failed closure, delayed closure including osteotomy is better for families compared to an alternative: operating when the baby is 1 or 2 days old. Because the pelvis is malleable in newborns, an osteotomy is not required, he says.
The newborn surgery was the standard practice earlier in his career and, “It's extremely emotionally traumatic on the parents to have their newborn baby undergo a major operation immediately after birth—that's one of the reasons to delay surgery," Jayanthi says. "By waiting a month or two as we do now, you need the osteotomy. But the advantage is it's less emotionally destructive. You can't overemphasize the importance of that."
Yet another possibility raised by the research is that the osteotomy, in fact, improves hip stability.
"The externally rotated hemipelvis on each side from the exstrophy, we will rotate inward," Klingele says. "I can see it being helpful to the hip, not just the exstrophy."
But, the surgeons say, because exstrophies are so rare, a multi-hospital study would be necessary to learn if that's so, and how hip problems and exstrophy are related.
If the surgery is found to cause the dysplasia, physicians may have to reassess what's become the standard of care.
In the meantime, Klingele and Jayanthi recommend that any children born with exstrophy undergo screening ultrasounds looking for hip dysplasia. If present, the dysplasia should be corrected. But those with normal hips at birth should be monitored to adulthood.
Mundy A, Kushare I, Jayanthi VR, Samora WP, Klingele KE. Incidence of hip dysplasia associated with bladder exstrophy. Journal of Pediatric Orthopaedics. 2015 Jun 3. [Epub ahead of print].