Measurement of selected hip, knee, and ankle joint motions in newborns.

As clinicians become more involved in preventative screening, assessment, and treatment of newborns and infants, an increasing need exists for quantitative, normal joint range-of-motion data for this population. We used a goniometer to assess in 40 healthy, full-term newborns the following passive ranges of motion: hip extension, knee extension, ankle plantar flexion, ankle dorsiflexion, and the popliteal angle. Every infant except one lacked full extension at both the hip and the knee. Plantar flexion was generally limited, but dorsiflexion was unlimited. Popliteal angle measurements showed the greatest amount of variation among the infants. Pearson correlation coefficients indicated that those infants with greater dorsiflexion tended to have less plantar flexion, and those with a greater limitation of knee extension measured with the hip extended tended also to have a smaller popliteal angle. Intrauterine position and newborn flexor tone are discussed as possible contributing factors to the results obtained in this study.