Normal ranges of popliteal angle in children.

Measurement of the popliteal angle is used to assess hamstring contracture in children with cerebral palsy. The popliteal angle in 482 normal children, 1-10 years of age, was measured. Using a 360 degrees goniometer, the popliteal angle was measured with the hip held at 90 degrees flexion to indicate hamstring muscle tightness. Between the ages of 1 and 3 years, the mean angle was 6 degrees (range, 0-15). At age 4, the angle rose to 17 degrees in girls and 27 degrees in boys (range, 5-45). At greater than or equal to 5 years the mean angle was 26 degrees with little change (range, 0-50). A popliteal angle of greater than 50 degrees in the above age groups indicates abnormal hamstring tightness.