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Research Reports: Barbara A Hungerford, Wendy Gilleard, Michael Moran, and Cathryn Emmerson Evaluation of the Ability of Physical Therapists to Palpate Intrapelvic Motion With the Stork Test on the Support Side PHYS THER 2007; 87: 879-887 [Abstract] [Full text] [PDF]

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Alternate Explanation

Jerry Hesch   (11 July 2007)

Alternate Explanation 11 July 2007
Jerry Hesch, PT na Send rapid response to journal: Re: Alternate Explanation jerryhesch{at}cox.net Jerry Hesch	This study is based on the premise that asymmetrical excursion of pelvic landmarks during the stork test is indicative of sacroiliac joint (SIJ) motion, based on a previous study utilizing skin markers[1]. Another researcher, Smidt, performed a study with skin markers and reported 9 degrees of SIJ motion with reciprocal straddle (RS) position[2], and, in a separate study, the range was 22 to 36 degrees of rotation [3]. However, the RS study was repeated with the use of tantalum balls implanted and measured with sterophotogrametric analysis, in which the excursion in several subjects did not exceed 2.1 degrees [4]. Another similar study reported that SIJ manipulation did not alter intra-articular position, but did in fact reduce pelvic landmark excursion [5]. This begs alternate explanations, other than intrartiular SIJ motion as causative of pelvic landmark asymmetry. We created a homemade model by xeroxing, onto plastic overlays, a medial view of the sacrum and a separate view of the ilium from an anatomical text. Lines were placed along the x and y axes so that they could be alligned and movement of ilium on sacrum could be measured. With an axis at the mid S2 joint, and a goniometer overlying the axis, I marked off 2 degrees of rotation within the joint, consistent with research reports [4]. The vertical excursion of the PSIS was equal to 1mm (1 degree). This should be doubled to 2mm (2 degrees), as the anatomical drawing was 50% the size of an adult pelvic model. Can clinicans actually perceive a 2mm excursion of the PSIS, or is the excursion of the PSIS much greater than the actual intraarticular SIJ motion? I submit that there is more going on than the singular model of SIJ motion. In the current study, the foot, ankle, knee, hip, and trunk (and pelvis) were not significantly constrained and thus the pelvis could be influenced by any or all of them; and compensatory motions could induce asymmetrical motions of the pelvis-as-a-unit, moving on the ovoid-shaped femoral heads. In fact, asymmetrical pelvic excursion is a normative function of gait[5]. Depending on the location of the axis of motion of the entire pelvis, the PSIS can move more so than the sacrum in the complete absence of intrarticular SIJ motion. A study using middle-aged persons with fused SIJs (ankylosing spondylitis) can be used to demonstrate this principle. Additionally, altered soft tissue tone in the lumbopelvic region during the stork test can give some artifact to actual bony landmark excursion. Alternately, the possibility exists that movement of pelvic landmarks in one plane may give false palpatory cues of motion in another plane. As the pelvis is foundational to both the spine and the lower extremities, its relevance to normal biomechanical function encourages continued study. The authors are to be commended for demonstrating a high degree of intertherapist agreement of pelvic landmark excursion with the Stork test. This work is foundational to future studies on the clinical utility of the stork test. We do not question their results, but rather their focus on intrapelvic motion versus motion of pelvis-as-a-unit, moving in 3-dimensional space. Jerry Hesch, MHS, PT Chris Gregor-Maxwell, MS, PT, AT The Hesch Method SIJ Seminars 1. Hungerford B, Gilleard W, Lee D. Altered patterns of pelvic bone motion determined in subjects with posterior pelvic pain using skin markers. Clin Biomech (Bristol, Avon). 2004;19:456-464. 2. Smidt GL, McQuade K, Wei SH, Barakatt E. Sacroiliac kinematics for reciprocal straddle positions. Spine 1995;20:1047-1054. 3. Smidt GL. Interinominate range of motion. In: Movement, Stability and Low Back Pain. London, England: Churchill Livingstone; 1997;187-191. 4. Sturesson B, Uden A, Vleeming A. A radiostereometric analysis of movement of the sacroiliac joints in the reciprocal straddle position. Spine 2000;25:214-217. 5. Tullberg T, Blomberg S, Branth B, Johnsson R. Manipulation does not alter the position of the sacroiliac joint. A roentgen stereophotogrammetric analysis. Spine 1998;23:1124-1129. 5. Levangie P. Hip joint. In: Levangie P, Norkin C. Joint Structure and Function. Philadelphia, Pa: FA Davis Co; 2005:366-371.