Lateralization of weight in the presence of structural short leg: a preliminary report.

Previous research has reported upon the use of a radiographic method to determine the presence of structural short leg using full spine radiography. In the current study, ninety-two (92) freshman students at the National College of Chiropractic in Lombard, Illinois were first measured for the presence of structural short leg and then placed on a modified Janse-Illi four quadrant weight scale. Measurements of weight were taken at fifteen, thirty, forty-five and sixty seconds. Precise placement of the feet were used. The data collected in kilograms of weight was then converted to total force in Newtons, and the data was normalized as percentage of total body weight. This was then compared to the side of structural short leg. Certain trends have tended to appear. Those subjects with small leg length differential had a greater tendency to bear weight upon the homolateral side of short leg, while those with greater degree of short leg (six millimeters or more) tended to bear weight upon the contralateral leg. It is felt that this is so due to a compensatory mechanism involving the gluteus medius muscle in its use as a "tie-rod" for pelvic function. The greater the degree of short leg, the more the gluteus medius is needed to level the pelvis, and thus the greater shift of body weight to the contralateral side. With a small leg length differential the compensatory mechanism is believed not to be activated, and thus weight bearing will occur on the homolateral side.(ABSTRACT TRUNCATED AT 250 WORDS)