Palpating the Pelvis for Torsion
Chiropractors, physical therapists, and osteopaths all seem fairly obsessed with the short-leg syndrome. partly because asymmetry of the lower extremipainful consequences for the patient, and partly because it is thought to have diagnostic significance. As someone who has spent many years studying the purported relation of leglength inequality (LLI) to pelvic torsion, it is not without a sense of chagrin that I have finally come to the conclusion that to make a mechanical diagnosis of the pelvis, it is usually better to examine the pelvis than, well, the feet (i.e., leg checking). This column develops the reasoning behind my conclusion.
In chiropractic, leg checking is used in a number of circumstances:
* To assess the status of the atlanto-occipital joint
* To look for evidence of anatomical LLI
* To serve as an outcome measure following provocative procedures (e.g., Derifield leg check,’ isolation testing,2 etc.)
* As an outcome measure to track the patient’s short- and long-term response to chiropractic adjustive care
* To identify pelvic torsion.3
Anthony Lisi and I coauthored a review article on pelvic torsion3 in which, among other topic areas covered, we described the various direct and indiect methods that have been claimed to rect pelvic torsion. These included radiographic, inclinometric, visual, palpatory, and reflex methods. Among the palpatory methods, some are direct, involving identification of pelvic anatomical landmarks, and others are indirect, such as pressure testing2 and leg checking.4
Although limitations of space prevent me from reviewing the advantages and disadvantages of these various methods for detecting pelvic torsion, let alone its clinical significance, at least let us assume it may be worth having a quick, low-tech, noninvasive method for identifying pelvic torsion from visit to visit. Since among the listed procedures, leg checking more than any other assessment procedure fits that bill, we need to see if current models connecting leg-check findings with LLI make sense. It is commonly believed that there is posterior innominate rotation on the side of a functional short leg, and relative anterior rotation on the opposite side.
One would assume that every leg checker, at some point in his or her career, conceives the thought, however transiently, that one leg appears shorter than the other simply because it is. Although the overall literature is somewhat equivocal, Friberg,5 using scanogram x-ray, found that about half of asymptomatic research participants and about 75% of patients with low-back pain exhibited LLI of 1/4″ or more. Since things are sometimes just as simple as they seem, given how common anatomic LLI appears to be, why start out by assuming that observed LLI results from subluxation in the pelvis, upper cervical area, or any other region of the body?
Even if observed LLI were to result from innominate subluxation (i.e., constitute functional LLI), there are problems with the mechanism that is usually described.The most common explanation of the Pl=short leg rule has a posterior swing of the innominate bone pulling the acetabulum, and therefore the lower extremity, cephalad.6i7This explanation can also be found in the physical therapy literature8 and apparently in osteopathy (presentation by David Grimshaw, DO, American Back Society, Las Vegas, Nevada, 1999).
This explanation requires the interinnominate axis of rotation to be posterior to the hip, perhaps through the sacroiliac joint. If the hip were indeed carried cephalad by this mechanism, however, so would the pubic ramus, and by a much larger amount (Fig. 1). In fact, a 6 mm short leg created in this way would luxate the symphysis pubis by causing a diastasis of around half an inch.9 For that reason, this explanation is not very appealing.
A more patient-friendly approach to explaining the association of posterior innominate rotation and the functional short leg invokes greater suprapelvic muscle tone on the side of posterior innominate rotation4,10,11 as part of a postural reflex. Relative hypertonus of the quadratus lumborum and/or sacrospinalis muscles, although unable to elevate the hemipelvis in a standing patient, would elevate the lower extremity in a prone or supine patient, creating a “muscular short leg,” as Schneider puts it.”
But why bother inferring pelvic torsion from a leg check, whatever the purported connection, when a direct method could be used? It is intuitively obvious that rotation of one innominate bone anteriorly, while the other rotates relatively posterior, must change the position of the anterior and posterior iliac spines (ASISs and PSISs). Levangie” has used sitting PSIS unleveling as evidence of pelvic torsion.
Why sitting? In the standing position, unleveling of the PSISs reflects the additive effect of both anatomic LLI and pelvic torsion. In fact, anatomic LLI can result in pelvic torsion,13-16 making it espedally difficult to tease out the separate contributions (anatomic short leg results in compensatory anterior innominate rotation). In the seated position, difference in structural leg length cannot affect PSIS positions, leaving pelvic torsion as the infinitely better explanation of any observed PSIS asymmetry.
Before jumping to the conclusion that seated PSIS asymmetry must reflect pelvic torsion, we still need to consider the possibility that congenital differences in innominate dimensions may account for observed PSIS asymmetry. Little was known about such hypothetical innominate asymmetry until fairly recently. Evidence from CT scanning17 and also from direct measuring18 tells the same story: congenital asymmetry of the innominate bones is minimal.Therefore, it is likely that seated PSIS asymmetry reflects pelvic subluxation, rather than innominate dysplasia.
The examiner should palpate the PSISs of the seated patient in 3 positions: coming down toward the patient from above with the thumbs pressing firmly into the soft tissue, coming in from below with firm pressure, and finally, right at the most posterior aspect of the PSISs. (See Fig. 2.) The examiner would have the most confidence in the exam findings when all 3 positions provide the same result. The inferior side, of course, reflects a relative posterior hemipelvic rotation and the superior side a relative anterior rotation. Which sacroiliac joint is to be adjusted, if not both, depends on additional clinical information – symptoms, orthopedic testing, postural evaluation, and reflex testing procedures.
The examiner will find it very interesting to observe what happens upon having the patient rise to the standing position with the thumbs still in place, and then sit again, thumbs still in place. Sitting asymmetry may disappear standing and reappear while sitting, or vice versa.This sitting-standing procedure is very useful to demonstrate the existence of anatomical LLI.
1. Cooperstein R.The Derifield pelvic leg check: a kinesiological interpretation. ChiroprTech 1991;3(2):60-65.
2. Fuhr AW, Green JR. Activator Methods analytic technique. In: ChiroprTech. St. Louis: Mosby; 1997. p. 92-1 10.
3. Cooperstein R, Lisi A. Pelvic torsion: anatomical considerations, construct validity, and chiropractic examination procedures.Topics Clin Chiropr 2000;7(3):38-49.
4. Cooperstein R. Integrated Chiropractic Technique: Chiropraxis. Oakland, CA: Selfpublished; 2000.
5. Friberg O. Leg-length inequality and low-back pain. Clin Biomech 1987;2:211-219.
6. Gatterman MI. Chiropractic management of spine-related disorders. Baltimore MD: Williams & Wilkins; 1990.
7. Bergmann T, Peterson DH, Lawrence DJ. Chiropractie Technique. NY: Churchill Livingstone Inc.; 1994.
8. Manheimer J, Lampe G. Clinical Transcutaneous Electrical Nerve Stimulation. Philadelphia: RA. Davis; 1984.
9. Cooperstein R. Functional leglength inequality: geometric analysis and an alternative muscular model. In: 8th Annual Conference on Research and Education; 1993; Monterey, CA: Consortium for Chiropractic Research; California Chiropractic Association; 1993. p. 202-203.
10. Travell JG, Simons DG. Myofascial Pain and Dysfunction: The Trigger Point Manual.The Lower Extremities. Baltimore: Williams &Wilkins; 1992.
11. Schneider M. The “muscular” short leg. Am J Clin Chiropr 1993;3(3):8.
12. Levangie PK. The association between static pelvic asymmetry and low-back pain [In Process Citation]. Spine 1999;24(12)1234-42.
13. Beaudoin L, Zabjek KF, Leroux MA, Coillard C, Rivard CH. Acute systematic and variable postural adaptations induced by an orthopaedic shoe lift in control subjects. Eur Spine J 1999;8(1): 40-5.
14. Drerup B, Hierholzer E. Movement of the human pelvis and displacement of related anatomical landmarks on the body surface.] Biomech 1987;20(10):971-7.
15. Young RS, Andrew PD, Cummings GS. Effect of simulating leg-length inequality on pelvic torsion and trunk mobility. Gait Posture 2000;11(3):217-23.
16. Cummings G, Scholz JP, Barnes K. The effect of imposed leg-length difference on pelvic bone symmetry. Spine 1993;18(3):368-73.
17. Badii M, Shin S, Torreggiani WC, Jankovic B, Gustafson P, Munk PL, et al. Pelvic Bone Asymmetry in 323 Study Participants Receiving Abdominal CT Scans. Spine 2003;28(12):1335-9.
18. Thompson DM, Vrugtman R. Biometrie comparison of the heights and widths of paired innomnates. J Chirop Educ 2003;17(1):39-40.
By Robert Cooperstein, DC
Copyright American Chiropractic Association Sep 2004
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