Knee Pain Can Point to Serious Hip Condition

By Dr. Eric W. Edmonds

There is occasion in medicine when all is not what it seems. This is when the practice of medicine becomes more of an art than an exact science. One example is when a child complains of significant knee pain that turns out to be hip pathology. Slipped capital femoral epiphysis (SCFE) is one infamous example of this problem.

A SCFE is actually a fracture through the growth plate of the upper end of the thigh bone (femur) that results in the head (capital epiphysis) of the thigh bone falling off the rest of the femur. If unchecked, or not diagnosed, a failure to treat this condition may lead to death of the femoral head, degenerative hip disease, gait abnormalities or chronic pain, quite serious consequences if missed in a 10- to 17-year-old child who has decades to live and play.

Many of these young athletes will have a few weeks or months of knee pain that in one game or practice becomes significantly worse. This is because the slip is gradual at first and then suddenly becomes unstable. Catching this problem early when your child is still willing to bear weight can mean the difference in a good outcome and a poor outcome.

Children do not always complain of knee pain though. Sometimes the pain is in the hips, but the classic teaching for medical students is that the pain from the hip will radiate down to the knee.

Other symptoms are waddling gait, loss of motion in the hip joint, a foot that wants to be rotated out more than usual or an unwillingness to bear weight on the affected limb.

In about 20 percent of children with a confirmed SCFE, X-rays will demonstrate that the “unaffected” hip is also a SCFE. An SCFE is most common is overweight boys. There does seem to be a predilection for African-American and Hispanic children, but it can occur in any race, ethnicity or gender. There are even cases when the affected athlete is thin.

Occasionally, an SCFE will even occur in someone under the age of 10. These slips can sometimes be associated with a hormone imbalance, especially those associated with thyroid problems.

The diagnosis is a combination of clinical assessment and X-rays which need to be of the hip, rather than the knee. Unfortunately, because many kids experience their pain in the knee, somewhere between 20 percent and 50 percent of SCFE are missed on their first presentation to a medical facility. Once discovered, an SCFE needs to be treated quickly.

There is no conservative nonsurgical treatment for this problem which will be treated with pinning of the SCFE to stop its progression. Depending on the age of the child, the unaffected side may also need to be pinned prophylactically.

Dr. Eric W. Edmonds is a pediatric and adolescent orthopedic sports medicine specialist at Rady Children’s Hospital-San Diego and an assistant professor of orthopedics at UC San Diego. He can be reached at sports@rchsd.org.