Saturday February 24, 1996

Smoking linked to Legg-Perthes disease

Parents who smoke at home put children at risk of developing Legg-Perthes disease, according to a study presented here Friday in scientific paper 137 and poster exhibit C-51.

Orthopaedic surgeons found in a survey of 172 children with Legg-Perthes disease that 86 percent live with parents who smoke. In a control group of 172 children who did not have Legg-Perthes disease, only 41 percent have parents who smoke. Diagnosis in the control group included foot deformities, hip dysplasia, scoliosis, cerebral palsy, among various orthopaedic disorders.

Statistical analysis shows an extremely strong association between smoking in the home and Legg-Perthes disease, said co-author John D. Osland, MD, chief resident, department of orthopaedics, University of Kansas School of Medicine, Wichita.

"The probability that these figures are just random is one in a million," Dr. Osland said.

The study was conducted among 344 patients at Shriners Hospital for Crippled Children, St. Louis, Mo.

While the exact cause of Legg-Perthes is unknown, the disease temporarily cuts off blood supply to the child's femoral head. Some bone dies, repair begins, and new growth occurs, only to be interrupted by a repetition of the cycle.

"Abnormal growth affects the developing femoral head and how well it fits into the hip socket," said Dr. Osland. "Walking difficulty and leg length discrepancy often result."

Dr. Osland said that Legg-Perthes occurs in one out of 1,200 people, but the frequency climbs to one in 100 among youngsters subjected to passive smoke at home.

As a matter of normal physical development, children between age four and eight have a poor blood supply to the femoral head, said Dr. Osland.

"Passive smoke further restricts this already limited vascular supply-to the detriment of the child," he said.

The onset of Legg-Perthes disease can occur anytime between age three and 12. Dr. Osland theorizes that some children are more susceptible to the effects of nicotine, which would explain why all siblings in one household are not affected.

While the severity of the disease varies, Dr. Osland said that parents should not permit any smoking in their home.

"For those children who already have Legg-Perthes disease, it is very important to eliminate all further exposure to smoke-before the other hip is affected," he said.

Caucasian male children have the highest incidence of this disorder. The rate among Caucasian female children is about one third that of Caucasian males.

"African-American children rarely get Legg-Perthes," Dr. Osland said, "because they have a better vascular supply to the femoral head."

Knee, groin or thigh pain or a limp is usually the first symptom of the disorder. Dr. Osland said that children with Legg-Perthes disease often have a delay in growth and skeletal maturation, or a delayed growth of limbs. Legg-Perthes patients have a higher incidence of arthritic hip problems later in life.

Co-author of the study with Dr. Osland is Perry L. Schoenecker, MD, associate professor of orthopaedics, Washington University School of Medicine and chief of staff, Shriners Hospital for Crippled Children, both in St. Louis.

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Last modified 27/September/1996