Friday, November 19, 2010
Top 100 Biomechanical Guidelines #23: Sacral Base Crucial Measurement for Short Leg Syndrome
The Sacral Base is at the base of the spine where the 5th Lumbar Vertebrae meets the sacrum. In the photo above, the sacrum rests below L5 and is slanted downward towards the right. This xray is called a Standing AP Pelvic Xray. To measure the sacral base difference, you draw a line along the sacral base until that line hits the ilium on the right and left sides at an equal spot. Then you drop a line down from these spots to the bottom of the xray plate. The sacral base measurement, also called sacral base unleveling, is the difference in heights between the two sides with one side higher. Of course, the base of the spine should be level with the ground. When treating leg length difference, xrays are taken when the initial treatment is not successful, or in chronic pain syndromes when you want to be as exact as possible. Comparing the hip height difference with the sacral base unleveling may help in deciding how much leg length difference should be initially corrected. In many cases, I will take these standing xrays after I am satisfied with my overall orthotic and lift therapies to see how far off I still am. The xrays should be taken in this case with shoes, orthotics, and lifts on and the patient standing in normal stance with the knees straight.