To the Editor:  

I would like to thank Harold I. Magoun, Jr, DO¹ and Dale E. Alsager, DO, PhD,^2,3 for their careful attention to my September 2007 case report in which I described a patient with chronic psoas syndrome.⁴ 

I am in agreement with Dr Magoun¹ that it is important, to correct pelvic dysfunctions before obtaining standing postural radiographs. This correction is, indeed, a necessary first step for postural radiographs to translate accurately a patient's leg length discrepancy into the sacral base unleveling that is measured using this technique. It is for this reason that—as I described in the three paragraphs before “Radiographic Findings” in my case report⁴—I note that the patient's pelvic dysfunction was corrected with restoration of pelvic symmetry before the postural radiographs were obtained. 

I am fascinated by Dr Magoun's disregard for standard postural radiographs, which he refers to as “an unnecessary technicality” after pointing out the importance of administering osteopathic manipulative treatment before obtaining them.¹ Although I congratulate Dr Magoun on his ability to prescribe heel lifts based solely on clinical evaluation, I will continue to use the quantitative measurement of sacral base unleveling to prescribe heel lifts, as described by Willman,⁵ Kuchera and Kuchera,⁶ and others. 

Dr Alsager^2,3 noted in his letters that, for postural radiographs to be valid, sacral base unleveling must be measured in reference to a vertical plumb line. The use of such a plumb line is an extremely important part of this technique. In my clinical practice, I use lead wire (like that used for tying flies for fishing), with a lead weight at the end, suspended from the ceiling, allowing gravity to provide a true vertical reference. Dr Alsager³ also expressed concern about the lack of a plumb line in the radiographic images shown in my case report.⁴ I would like to note that these radiographs were taken using a leveled bucky, and the markings and measurements in the radiographic images are merely representations of the actual markings and measurements used during evaluation of the patient. 

Another concern expressed by Dr Alsager³ is important to discuss: where does the clinician draw the horizontal reference lines for femoral head height on a radiographic image when there is an artificial hip? And perhaps a more important, related question might also be asked: where does the clinician draw the vertical reference lines off the femoral heads when there is an artificial hip in the radiographic image? These are two conundrums to which I believe my case report⁴ provides ready solutions. 

The horizontal reference lines (lines 1 and 2 in Figure 2, 2007;107:417) are usually drawn across the highest point of the natural femoral head. An artificial femoral head is smaller, however, and therefore lower, when compared to the natural femoral head. Should the horizontal lines incorporate the artificial acetabular component, or should they be across the artificial femoral head, as suggested by Dr Alsager?³ I believe this question is redundant, because the horizontal lines do not come into play with the measurements used. In fact, regardless of the femoral head heights, the only actual concern in evaluating a leg length discrepancy is how the discrepancy affects the rest of the body—and this is determined by measuring the amount of sacral base unleveling created by the discrepancy. Thus, the only relevant measurement is the angle created by the unleveled sacral base against the vertical plumb lines drawn off of the femoral heads. 

It is crucial to determine the correct placement of the vertical plumb lines off of the femoral heads (lines 3 and 4 in Figure 2), generally drawn in this technique from the tallest points of natural femoral heads. These lines and the line that is drawn across the unleveled sacral base (line 7 in Figure 2) are used to calculate the proper-sized heel lift to prescribe. With an artificial hip, I believe that the ideal position to place the vertical plumb line from the artificial femoral head is at the same distance medial to the greater trochanter as is the contralateral plumb line from the natural femoral head. 

Again, I am grateful for the interest generated by my case report.⁴ I hope that other osteopathic physicians and their patients may benefit from the details of this discussion.