Our little grandson is being evaluated for a hip problem that no one can seem to figure out. Part of the problem (as we were told) is that no one really knows what ‘normal’ hip motion is — so he’s on the edge between what seems like ‘normal’ and ‘abnormal’. Does that seem right to you?

Although we have some general guidelines for range-of-motion measurements in adults, normative values for children of varying ages are not available. Normative values means you can find a chart with the expected measurements for each of these areas based on age and sex (male and female).

Other measures of things like grip strength, height, weight, head circumference, and even IQ (intelligence quotient) have normative values. When it comes to evaluating and treating hip problems in children, it would be helpful to know what is normal motion and what is not.

However, a recent study was done at Children’s Hospital of Philadelphia (CHOP) to determine what constitutes normal (versus abnormal) hip motion in normal, healthy children.. Hip measurements were taken of children who came to the hospital for treatment of a broken arm. There were no leg injuries or other compromising health conditions. There were 252 children involved in the study (that’s 504 hips to measure).

Measurements were taken in two positions lying down: supine (face up) and prone (face down). Measurements taken in the supine position included flexion, abduction (leg away from the midline), adduction (leg toward the midline), and rotations (internal and external). Extension and rotations were measured from the prone position.

In general, it appears that hip range-of-motion decreases as children get older. This effect is more obvious in boys than in girls. Differences between boys and girls at different ages are presented but the study was not designed to compare differences based on race (e.g., Whites, Blacks, Hispanics, Asians). That will be something future researchers may address. A graph showing the range and averages over time for each measured motion was included based on age and sex.

The information gathered in this study will help physicians evaluating children for problems such as slipped capital femoral epiphyses (SCFE), synovitis or other inflammatory hip problems, and femoroacetabular impingement (FAI). Such diagnoses depend on altered range-of-motion as a primary measure. To really help in the evaluation of all pediatric hip diseases, the additional information about differences based on race will be needed.

Until the values from this study can be repeated and confirmed, physicians and physical therapists measuring hip motion in children will continue to compare one side to the other looking for differences. With clinical experience taking these kinds of measures, health care professionals can usually tell when something is not ‘normal’. The gray areas where something isn’t quite right remain a challenge that will require additional testing and possibly imaging studies (e.g., X-rays, CT scans, MRIs).