Relationship of functional leg-length discrepancy to abnormal pronation

The objective of this study was to determine whether a correlation exists between abnormal pronation and functional leg-length discrepancies. Visual assessment and a pelvic thrust maneuver were used to identify the functionally short leg in 56 indigenous Mexicans (20 males and 36 females; mean age, 33 years; mean weight, 59 kg; and mean height, 1.60 m). The Foot Posture Index was used with a modified stance position to identify the more pronated foot. The posterosuperior iliac spines were used to identify the "relative" position of the innominate bones. The raw data obtained from this study were evaluated using the McNemar test for paired proportions. A significant positive correlation was found between abnormal pronation and hip position and between hip position and functional leg-length discrepancy. These results are consistent with a theoretical ascending dysfunctional pelvic model: Abnormal pronation pulls the innominate bones anteriorly (forward); anterior rotation of the innominate bones shifts the acetabula posteriorly and cephalad (backward and upward); and this shift in the acetabula hyperextends the knees and shortens the legs, with the shortest leg corresponding to the most pronated foot.