By J. W. Gudgel, DC, PT, Impulse Technique instructor

Our foundation-based approach in the Impulse Adjusting Technique starts with our five-step lumbopelvic analysis beginning with the pelvis and bringing in considerations of the hip joints, lower extremity, and suprapelvic musculature.

Actually, we begin the analysis with a good patient history, but the actual physical exam starts with the sacroiliac (SI) joint. The Mayo Clinic stated several years ago that 74 percent of the diagnosis comes from the history. So, while it is true that the patient’s diagnosis may be a herniated lumbar disc, the underlying cause could have been longstanding pelvic malalignment transmitting torque or stress into the lumbar spine eventually weakening the outer annular fibers.

A good history will lead the examiner toward the diagnosis, but a good exam is necessary to determine the underlying cause of the problem. Next, the examiner subjects the patient to a series of tests to either rule in (specificity) or rule out (sensitivity) various conditions.

The history of a sacroiliac lesion as opposed to a disc lesion differs in that the disc lesion, if severe enough, will cause positive neurological signs (diminished reflexes, paresthesia in the lower extremity, and muscle weakness) while the sacroiliac lesion does not. However, disc lesions that are not compromising the nerve root (mechanically or chemically) will not produce these neurological deficits and the symptoms will be similar to an SI lesion (pain in the back, hip, and posterior thigh with varying degrees of paresthesia and “functional weakness,”1 but rarely any true motor loss).

While the vast majority of the patients we see don’t have neurological deficits, their presence is an indication of a something serious and the doctor should immediately consider co-treating with a specialist in case the patient does not improve quickly and requires surgical

The five-step analysis that we have developed objectively evaluates the sacroiliac joints against the lumbar spine while seeking to determine involvement of the hip joints and supporting musculature from the quadratus lumborum muscles and muscles of the lower extremity including the lateral hamstrings and peroneal muscles (Table 1).

The assessment begins with an analysis of the pelvis, specifically the sacroiliac and hip joints, to determine subluxations and dysfunction resulting from pelvic malalignment or direct trauma. Why are the hips examined as part of the SI joint analysis? As Cibulka said, the hip “drives” the
SI joint and loss of normal hip rotation is strongly correlated to SI joint dysfunction. Thus, we begin step one with the Nachlas test. This test has high validity (as does pain in the SI joint with compression) whereas many commonly used orthopedic tests do not.

There are many references for the Nachlas test. Both Cipriano’s and Haldeman’s texts note that pain in the low back with the Nachlas test is indicative of a lumbar disc or facet lesion, whereas pain in the buttock is indicative of an SI joint lesion. Evans further states that the Nachlas test may reveal a concealed disc lesion.

We begin by performing the Nachlas test bilaterally noting if and where the patient perceives pain or tightness (Figure 1). Even in the absence of patient symptoms with the tests, the examiner notes the degree of knee flexion allowed at each knee when flexed, any tilting, rolling, or elevation of the ilium, and any gluteal or lumbar muscle reactions (felt with the free hand placed over the patient’s SI, hip, low back area while the knee is being flexed).

Proper performance of the Nachlas Test for lumbopelvic analysis is not as simple as it appears. Many doctors are “heavy-handed” and they try to flex the patient’s knee as far as possible. The test is more refined than the total amount of knee flexion that can be attained at each knee. This will become apparent below. While there are abundant references for the implications of the Nachlas test, there is very little written about the mechanism of the test (how does it work?).

The “mechanical” explanation is that as the patient’s knee is flexed, the extensors of the knee are stretched. This primarily includes the three quadriceps muscles and the rectus femoris. As kinesiology tells us, when a joint is flexed, the two-joint muscles that cross that joint (and another joint either proximal or distal to the joint being flexed) will “run out of slack” or reach the point of tissue resistance quicker that those one-joint muscles that only cross one joint.

The quads are one-joint muscles in that they only cross the knee joint, but the rectus femoris is a twojoint muscle crossing both the knee and the pelvis (it originates on the anterior inferior iliac spine and inserts on the tibial tubercle). Inasmuch, during performance of the Nachlas test, the total amount of knee flexion of each knee is not important.

The important point is whether or not the range of motion are equal, symmetrical or asymmetrical (Figure 2). The point of tissue resistance is the point where the knee begins to resist further flexion and would “spring” back toward extension if the examiner were to release the leg. During the test, the examiner must apply the same amount of force to each knee. The knee that reaches the point tissue resistance first is the “reactive” leg.

Obviously, the point of tissue resistance varies with each patient. Some patients will have an extremely large amount of flexion, sometimes to the point where the heel touches the buttock. Others will show resistance as soon as 80 degrees or less of knee flexion (excluding those patients with knee pathology or total knee replacements).

However, with most patients one knee will not flex as far as the other. Remember, the doctor is trying to determine which knee reaches tissue resistance first.
What causes one knee to reach tissue resistance sooner than the other (asymmetry of knee flexion)? And what does this asymmetry, when present, mean? Again from a mechanical standpoint, one could liken this to pulling a rope attached to a “freely movable” object. As one pulls on the rope, the object moves toward you. The less “freely movable” the object it is, the more force you have to apply to move the object.

If the object were an automobile wheel attached to an axel about which it could rotate (a fixed axis of rotation), and the rope was wrapped around to the outer edge of the wheel, then when the rope is pulled the wheel would rotate about the axel rather than come closer to you. If the wheel’s brake were engaged, then the wheel would not rotate freely and would require more pulling force. This is the situation with the rectus (the rope) and the ilium (the wheel).

The force is the tibia tubercle moving distally as the examiner flexes the knee, thus applying force to the muscle (rope). The muscle (rope) is attached to the anterior inferior iliac spine of the ilium (wheel) and the ilium has an axis of rotation about the pelvis at the SI joints. As the muscle (rope) is pulled, the ilium rotates clockwise (anteriorinferior). The PSIS moves anterior and superior.

If the ilium were fixated (wheel’s brake were engaged) then the muscle (rope) would become “taut” (point of tissue resistance) before any movement of the wheel would occur. Failure of the ilium to move freely into an anterior tilt is interpreted as a “PI ilium” fixation or subluxation. And the contralateral ilium will seek a “balanced” pelvis position so it moves into an “AS” fixation or subluxation.

Derefield, and others, have utilized a bilateral Nachlas test to analyze the pelvis and spine. In this manner, both knees are flexed and according to changes observed in the leg lengths conclusions are drawn. While the unilateral Nachlas test is valid (as discussed above), research has found that the bilateral Nachlas test has indeterminate reliability and the isolation tests are completely unreliable.

Thus the correct application of the Nachlas test tells the examiner of the patient’s current pelvic malalignment pattern and SI subluxations. In next month’s issue I will discuss the “neurological” component of the Nachlas test and how the hips relate to pelvic malalignment as I address step two of our five-step lumbopelvic analysis in Impulse Adjusting Technique.