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When a limp signals something more serious: make sure to examine the hips.

LAS VEGAS -- Of all the conditions that may cause a child to limp or refuse to walk, septic arthritis is an emergency with a time-dependent outcome, Dr. Michael J. Goldberg said at a meeting sponsored by the American Academy of Pediatrics and California Chapter 2 of the AAP.

"This is one of the critical things in orthopedics," said Dr. Goldberg, who chairs the department of orthopedic surgery at Tufts-New England Medical Center in Boston. "'If not treated early--generally by 4 days--the joint is destroyed."

The classic signs include fever and malaise, refusal to walk, and a painful, restricted range of motion in the hip. Affected children generally have high white blood cell counts and erythrocyte sedimentation rates. "But one or more of these findings may be absent, so keep your suspicion high," he said. "The best way to diagnose a septic joint is by joint aspiration. Laboratory studies, ultrasounds, and bone scans are not substitutes for joint fluid analysis."

Other conditions that cause a child to limp include the following:

* Developmental dysplasia of the hip (DDH). "We'd like to think that we diagnose DDH in the newborn period, but we know that regardless of the diagnostic technique--whether it's by physical exam or screening by ultrasound--1 in 5,000 children will be diagnosed with DDH after the age of 15 months," Dr. Goldberg noted. "So when you see a 1-year-old child who is limping and does not have a normal gait, keep this diagnosis in mind."

* Toxic synovitis. This is probably the most common cause of limp in children aged 3-5 years. "It's a very bad name because it's neither toxic nor does it [involve] synovitis,'" Dr. Goldberg noted. "'Observation hip' is probably a better name. What I Fred is that the acute onset is in the morning. The child may seem fine the night before, but will awaken with a limp" or even refuse to walk.

The child does not look ill, he said, and if you examine the hip, you observe a nearly full range of motion. Labs and x-rays are normal.

"It's a diagnosis of exclusion," he said of toxic synovitis, adding that there is no specific test for the condition. "So it is either a classic pathology, such as this, or a diagnosis where you exclude other things by x-ray, CBC, ESR, or something else. Restricting activity for a few days with rest at home is usually all that's needed. The exact cause is not known."

If the child is not better in a few days or if the condition recurs, think of another diagnosis. "It's not toxic synovitis if it's prolonged, or if you have abnormal lab results, or if you see something abnormal on the x-ray," he said.

* Legg-Calve-Perthes disease. The classic finding of this condition on x-ray is avascular necrosis of the femoral head. The disease mainly affects children aged 3-8 years, tends to strike boys more often than girls, and frequently causes a painless limp.

"The child does not refuse to walk," Dr. Goldberg said. "He runs and plays but seems to be having this favoring and limp. ... These are kids who are constantly in motion. They're not hyperactive, but they are [seemingly] always moving." These children also tend to be small for their age and to have smaller hands and feet, he noted.

You might find that the range of motion in these patients is restricted only with decreased abduction and internal rotation. "Otherwise, you may have a fairly good range of motion," he said. "This is different from a septic joint, where you'll have restriction in all ranges of motion. Legg-[Calve]-Perthes is unilateral in 90% of cases."

Current treatment options vary, and include doing nothing, initiating exercise and range-of-motion activities, using home traction, bracing all day or all night, and performing surgery to realign the socket on either the acetabulum side or the femur side.

"No matter what you do, about 15% of cases have bad results and 85% have good results, which makes the best treatment difficult to decide," Dr. Goldberg noted.

Whenever you see what appears to be bilateral Legg-Calve-Perthes, think about the following conditions: skeletal dysplasia, hypothyroidism, Gaucher's disease, steroid use, juvenile rheumatoid arthritis, systemic lupus erythematosus, hemoglobinopathy, old DDH, and tuberculosis.

* Slipped femoral capital epiphysis. This condition generally affects children aged 10-14 years, who may present with a painless limp. "When it is painful, it is knee pain that they report," Dr. Goldberg said. "'Sometimes the thigh and inner thigh are painful as well.

"Obesity is an important contributing factor," he noted.

The telltale sign is that as the hip is flexed, it goes into external rotation. If you find this, "refer promptly," he said.

Dr. Goldberg emphasized the importance of examining the hip during the patient's initial visit and always prior to ordering x-rays, MRI, or arthroscopy of the knee. "MRI and arthroscopy do not diagnose a slipped epiphysis," he said.

He recommended this approach with all cases of children who present with knee pain. "Children like to attribute their knee pain to something," he said. "It doesn't matter what they say happened. If they have knee pain, get the diagnosis carefully, but remember to examine the hips."

Other causes of limp to include in your differential diagnosis are neuromuscular cerebral palsy, leg length inequality, juvenile rheumatoid arthritis, tarsal coalitions, and child abuse.

Growing Pains Not the Culprit

Contrary to what some parents and grandparents will tell you, growing pains do not cause a child to limp, Dr. Michael J. Goldberg said.

"Growing pains occur at night, usually within the first few hours of going to sleep," he said. They may also cause the child to wake up in the middle of the night in pain, which is often located in the interior aspect of the tibia or thigh, or occasionally in the posterior calf.

Pain occurs between joints, not in the joint itself. "There is no limp or restricted activity," he noted.

The physical exam is normal and the precise etiology is not clear. Growing pains are "probably an overuse phenomenon of some sort," Dr. Goldberg said.
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Title Annotation:Children's Health
Author:Brunk, Doug
Publication:Family Practice News
Geographic Code:1USA
Date:May 15, 2004
Words:1014
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