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Chronic and Acute Low Back Pain and Its Relationship to the Sacral X-Axis, Leg Length Changes, Sciatica, Abdominal Pain, Idiopathic Scoliosis, and Incontinence

DonTigny, Richard L. PT

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Topics in Geriatric Rehabilitation: January/March 2020 - Volume 36 - Issue 1 - p 3-10
doi: 10.1097/TGR.0000000000000258
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Research into the sacroiliac joint (SIJ) as the cause of low back pain (LBP) was plentiful in the early 1900s, but lost focus on the SIJ with the discovery of the herniated intervertebral disc (herniated nucleus pulposus). When it was finally apparent that the disc was not the center of the problem, disc research was set aside by several varieties of innovative rhetoric, which further obscured the focus on a specific cause of LBP.

A personal narrative is necessary. In 1964, I saw a typical patient with acute LBP and I did everything I could to relieve her with heat, electrical stimulation, massage, and posture training, but nothing helped her. Of course, I made her another appointment. She called the next day to cancel her appointment because she was free of pain. I asked her what she did to relieve her pain because I had not helped her and perhaps I could learn from her experience.

She reluctantly told me, “I fell off of my tractor.” I suspected that having an office full of tractors was not going to help much, but I realized that LBP was most likely to be a reversible, biomechanical problem and if I could ascertain the nature of this problem I could have patients free of pain immediately. I had the basic mechanism within a few weeks.

I knew that back pain can be caused by lifting, bending, lowering, shoveling, sweeping, posture, pregnancy, and weak, protruding abdominal muscles, all of which are caused by an anterior shift in the line of gravity with an anterior rotation of the innominates. I reasoned that if an anterior innominate rotation caused pain and dysfunction then a manual posterior innominate rotation should relieve the pain. Most importantly I learned that anterior innominate rotation altered pelvic structure in such a way as to cause the legs to appear to lengthen with dysfunction and to shorten with a correction in manual posterior innominate rotation. And it did and does. After a few years I had analyzed the basic mechanics and made measurements of the posterior superior iliac spine (PSIS). In the late 1960s, I wrote it up and sent it in to the physical therapy journal. They reviewed it and returned it 4 times before asking me to send it to another journal, which I did. Evidently they had no use for a method of treatment that brought immediate relief of pain (Figures 1–7).

Figure 1.
Figure 1.:
The transverse sacral x-axis pivots slightly in its shallow sockets when the pelvis is symmetrical during flexion and extension with weight-bearing. These sockets are located at the PIIS. A kinetic loading of the super-incumbent weight occurs anterior to these pivotal points on the posterior interosseous ligaments. A secondary kinetic balancing loading occurs on the sacrotuberous ligaments posterior to these points. Active force couples are created. Note the iliac tuberosity at the PSIS and how it overlies the sacrum and functions with posterior innominate rotation and asymmetry to cause the sacrum to flex laterally toward the side of loading. Note also the angle of the sacroiliac joints, which without ligamentous restraint, would tend to fall away from the innominates with increased loading. Increased loading also increases the kinetic loading as shown in Figure 2. PIIS indicates posterior inferior iliac spine.
Figure 2.
Figure 2.:
The sacrum is slung from the ilia and is motion sensitive. The kinetic loading creates parallel interactive force couples that act to facilitate pelvic movement at pelvic asymmetry to the right and left.
Figure 3.
Figure 3.:
Pelvic movement during normal ambulation causes lateral sacral flexion, which, in turn, creates a kinetic oblique force couple that reverses at mid-step when the innominates are symmetrical. Right lateral sacral flexion creates a transient oblique axis from right sacral S3 to the superior aspect of left sacral S1 to drive an oblique flexion-rotation of the sacrum in order to decrease loading on the femoral head. The pelvis moves through symmetry at mid-step, moves to asymmetry, and then creates a transient oblique axis from left sacral S3 to the superior aspect of right sacral S1 to drive an oblique flexion-rotation of the sacrum to the contra lateral side.
Figure 4.
Figure 4.:
Sequence for right loading with posterior rotation of right innominate and with anterior rotation of the left. The ileal surface of the right innominate joint pushes down on the right sacroiliac joint surface, loading the posterior interosseous ligaments and creating a lateral sacral flexion. Movement is on an oblique sacral x-axis.5 The asymmetric pelvis reverses asymmetry instantly at mid-step when the pelvis is instantly symmetrical. This innate example of biotensegrity is probably the peak result of evolutional biomechanics in the pelvis.
Figure 5.
Figure 5.:
Instructions for positioning of weight-bearing, long straddle position, and asymmetric pelvis for radiology. Note movement at PSIS. PSIS indicates posterior superior iliac spine.
Figure 6.
Figure 6.:
Anterior oblique pelvic movement with a long step to the right and then a long step to the left. Note the oblique sacral x-axis movement. Note difference in height of PSIS right and left. Note the TSLA is unchanged. Note also how movement of the PSIS pivots on the transverse loading axis at the same time oblique sacral movement occurs on the force-dependent oblique axis. PSIS indicates posterior superior iliac spine.
Figure 7.
Figure 7.:
Sacral oscillation during ambulation causes the spine to move and function as a descending waveform, which decreases the alternate loading motion to the head to stabilize the visual plane. Dysfunction of the SIJ will negate this waveform and increase loading to the femoral heads. SIJ indicates sacroiliac joint.


Low back pain is essentially always caused by an anterior shift in the line of gravity with loading. Lifting, bending, sweeping, vacuuming, a pendulous abdomen, forward head, etc, are all causative movements. Pathology in posterior innominate rotation cannot occur because posterior innominate rotation drives the sacrum caudad.

Leg lengthening and shortening

An anterior shift of the line of gravity over the acetabular axis changes several critical relationships. In 1906, McConnell and Teall1 described the manner in which the pelvis moves up posteriorly on the sacrum and downward anteriorly causing an apparent increase in leg length, which can be demonstrated by examining the heels or approximating the medial malleoli with the patient supine.1 Chamberlain2 identified this dysfunction with stereographic roentgenograms in 1930 (Figures 8–11).

Figure 8.
Figure 8.:
Changes in the pelvic structural relationships from posterior innominate rotation (PR) to anterior innominate rotation (AR). With anterior innominate rotation, first the line of gravity moves forward. This can be symmetrically or obliquely symmetrical. In the absence of support from the rectus abdominis, the innominates rotate anteriorly on the acetabular axis. With anterior innominate rotation, the acetabular axis rotates downward making the leg to appear longer if the patient is supine or making the crest appear higher when the patient is sitting or standing.
Figure 9.
Figure 9.:
As the innominates rotate anteriorly on the acetabular axis, the sacral angle is changed increasing shear on the lumbosacral joint and increasing lumbar lordosis. (A) Kinetic loading is increased on the posterior interosseous and sacrotuberous ligaments. (B) Anterior torsion is placed on the sacral x-axis at the PIIS. (C) The PSIS rises relative to the acetabula and causes the leg length to appear longer. This is a measurable motion. (D) A rotational shear force input is primarily on the sacral x-axis points on the gluteus maximus and the piriformis. PIIS indicates posterior inferior iliac spine; PSIS, posterior superior iliac spine.
Figure 10.
Figure 10.:
Take special note of the direction of dysfunction on the sacral x-axis, which spreads the sacroiliac joint slightly increasing shear at the PIIS. The PSIS will rotate vertically, anteriorly, and somewhat laterally from 1 to 1.5 cm, pivoting on the PIIS. The PIIS will always be the most painful point with this dysfunction. A diagnosis can be made by this painful point alone. PIIS indicates posterior inferior iliac spine; PSIS, posterior superior iliac spine.
Figure 11.
Figure 11.:
Some of the critical areas of chronic and acute low back pain are affected by anterior innominate rotation on an acetabular axis. (A) The shear points are the locations of the transverse sacral x-axis shallow sockets at the PIIS on which the innominates sublux superiorly. (B) The direction of dysfunction is always in anterior innominate rotation usually bilaterally or sometimes with one side slightly more than the other. (C.) The long posterior interosseous ligaments are stretched and painful. (D) The sacral and innominate origins of the gluteus maximus are stressed. Each appears to have a slightly different function during the gait cycle. (E) A slender slip of the ileal origin of the piriformis is attached to the superior margin of the greater sciatic notch and is subject to separation with anterior innominate rotation at the shear points, which are the lateral points of the transverse sacral x-axes. (F) Rauber-Kopsch found that a part of the sciatic nerve passed through the piriformis muscle and joined the other portion of the nerve to form a main trunk at the caudal margin of the muscle.9 PIIS indicates posterior inferior iliac spine.

Sciatica was found to be caused by dysfunction in the SIJ at least 90 years ago when in 1928 Yeoman reported that sacroiliac arthritis was responsible for 36% of the cases of sciatica.3 In 1925, Danforth and Wilson4 attempted to determine the relationship between the SIJ and the sciatic nerve, but concluded that as there was no canal nor semblance of a canal anywhere near the joint the SIJ could not be at fault. However, no consistent test could be found and no bony axis of rotation has been described or measured.5 Sciatica was also associated with the disc, so when sciatica was found, the SIJ was eventually ignored and the disc was accepted as the source of sciatica (Figure 12).

Figure 12.
Figure 12.:
Measurements and x-rays taken of the SIJs before and after correction of SIJD demonstrate a movement of the PSIS caudad and medially on the sacrum of about a centimeter with correction. Measurement of movement in the PSIS before and after correction with a manual posterior innominate rotation was from 1 to 1.5 cm, with an extreme of 2.5 cm with a severe subluxation of the SIJ.10 Any movement of the innominate bone cephalad and laterally on the sacrum will put a vertical shear on the 2 conjoint origins as well as the conjoint origin of the iliacus (Figure 5). The sciatic nerve exits just beneath the piriformis and frequently penetrates the piriformis. Any pathological event that affects the piriformis can affect the sciatic nerve. A dysfunction of the SIJs in anterior rotation will cause a vertical shearing at the PIIS, at the juncture of the conjoint origins of the piriformis. PIIS indicates posterior inferior iliac spine; PSIS, posterior superior iliac spine; SIJ, sacroiliac joint; SIJD, sacroiliac joint dysfunction.

Palpable trigger points are found in these areas. This dysfunction of the SIJ is responsible for the deep buttock pain at the posterior inferior iliac spine (PIIS) always found with sacroiliac joint dysfunction (SIJD). A trochanteric bursitis and pain down the iliotibial band may also occur depending upon the degree of shear and separation of the gluteus maximus (Figures 13 and 14).

Figure 13.
Figure 13.:
When the line of gravity moves anterior to the acetabula, the force in anterior innominate rotation increasing shear forces on the piriformis and gluteus maximus and increasing tension on the long posterior sacroiliac ligament, the hamstrings and the sciatic trunk. The sacral axis will rise on the sacrum with a slight, but measurable subluxation. This will create a palpable, painful line across the buttocks from the PIIS to the trochanter and thence down the lateral thigh to the lateral knee. This is the mechanism of acute and chronic low back pain. PIIS indicates posterior inferior iliac spine.
Figure 14.
Figure 14.:
Note the apparent subluxation in anterior innominate rotation at the left end of the sacral x-axis. (Courtesy of Mitoshi Fukushima, MD, PhD, Fukushima Orthopaedic Clinic, 13-9, 1-choume, Kairouen, Saeki-ku, 731-5135 Hiroshima-shi, Japan.)

Abdominal pain with LBP

Sacral-subluxation may also cause abdominal pain at Baer's sacroiliac point, which is on a line from the umbilicus to the superior iliac spine, 2 inches from the umbilicus.6–8 I saw a patient who had LBP with abdominal pain for 4 years. She had both ovaries removed with no relief. Both the abdominal pain and the LBP were immediate relieved with a manual bilateral posterior innominate rotation (Figure 15).

Figure 15.
Figure 15.:
Baer's point can be present on either side. This painful point will be relieved with a bilateral manual posterior innominate rotation.

Idiopathic scoliosis

An asymmetrical anterior innominate rotation with a long leg and a high iliac crest can cause a scoliosis without pain in prepubertal children, when standing or sitting. This must be examined for when doing scoliosis checking. This can be corrected immediately with a manual posterior innominate rotation correction. The parent must be instructed in follow-up.


The anterior innominate rotation will also approximate the ischial tuberosities toward the sacrum, thus slightly loosening the muscles of the pelvic floor, and cause some degree of incontinence. A few months following one of my workshops, I received an e-mail from one of the therapists who attended. She told me that she had been teaching incontinence training for women in Hong Kong. She also told me that frequently following my corrections for LBP the patient no longer needed the incontinence training.

The pudendal nerve from the sacral plexus passes next to the piriformis and innervates both the anal sphincter and the external urethral sphincter, thus adding another degree of complexity to the Piriformis syndrome. Incontinence usually reverses with a correction in manual posterior innominate rotation in a day or so.


At the initial meeting because acute and chronic can have so many different issues, it is imperative to first establish the presence or absence of SIJD. With the patient standing or prone, first locate both PSIS and the let your fingers drift caudad and somewhat medially to the PIIS. With dysfunction the long posterior iliac ligament will be tender in this area. When you reach the PIIS, this axis point will be very tender, usually one side more than the other.

With the patient lying supine and the operator at the foot of the table, hold both feet so that the malleoli are approximated in the midline and compare the relative leg length. Take note that one side may be longer or shorter than the other. Stand to one side of the patient and do a passive straight leg raise to about 35° to 40° and put traction to tolerance on the leg at that angle. Gently lower the leg and check the relative leg length again. That leg will probably appear to shorten from 1 to 1.5 cm or more. Move to the other side and do the same procedure and that leg will also appear to get shorter. Move back to the first leg and repeat the procedure. Keep repeating right to lift passive straight leg raise to each leg as long as a shortening of the leg appears.

Next have the patient hold on knee-to-chest with both arms wrapped around it and do a strong isometric hip extension. Check the comparative leg length again. Did it appear to shorten anymore? Have the patient repeat the isometric hip extension on the other side and check the leg length. Keep repeating until neither leg shortens anymore.

Instruct the patient in a self-correction exercise and have them repeat it every few hours until the next appointment. The next time you see the patient have them demonstrate the exercise that you had instructed them in as it may be necessary to repeat the instructions. Now repeat your corrections, checking leg length again, and instruct them in a strong isometric correction. Make another appointment only if the patient wants to return. Give them a printed booklet of instructions and have them return if they cannot properly correct. I used to average 2.8 treatments per patient.

The patient must be instructed in how to prevent recurrence of this problem by supporting his pelvis up with his abs whenever he leans forward to perform any task. Joint instability can be controlled with an SIJ belt worn just below the crests and above the trochanters. We have had some good results with injections of platelet-rich plasma into the PIIS.


Initial innominate movement is a weight shift to the side of loading and then a posterior rotation of the thigh to be lifted on an axis through the pubic symphysis, which causes a lateral sacral flexion and an oblique sacral axis. Note also how movement of the PSIS pivots on the transverse loading axis at the same time oblique sacral movement occurs on the force-dependent oblique axis.

As the pathological force of anterior innominate rotation can cause multiple symptoms immediately, you can expect that a corrective force in manual posterior innominate rotation to relieve all of those symptoms immediately. Pathology of the SIJ s is far more complex and affects many more patients than previously suspected, but can be easily detected merely by palpating for pain at the PIIS. A manual correction in posterior innominate rotation is vastly more simple and effective than other methods of treatment, but is seldom prescribed.

Lack of appropriate education and the substitution of creative rhetoric for more accurate and appropriate pathology have forced a lack of research on the SIJs and the pelvis. This has compelled some insurance companies to avoid payment on the diagnosis and treatment of dysfunction of the SIJs. There are some leaders in this field who are reluctant to publish sound research for fear that any effective research may prove detrimental to the distribution of the huge amount of funds presently generated for the treatment and research of LBP.


1. McConnell CP, Teall CC. The Practice of Osteopathy. 3rd ed. Kirksville, MO: Journal Printing Co; 1906.
2. Chamberlain WE. The symphysis pubis in the Roentgen Examination of the sacroiliac joint. Am J Roentgenol. 1930;24:621–625.
3. Yeoman W. The relation of arthritis of the sacroiliac joint to sciatica. Lancet. 1928;2:1119–1122.
4. Danforth MS, Wilson PD. The anatomy of the lumbo-sacral region in relation to sciatic pain. J Bone Joint Surg. 1925;7:109–160.
5. Platt H. Backache—sciatica syndrome and intervertebral disk. Rheumatism. 1948;4:218.
6. Baer WS. Sacro-iliac strain. BullJohns Hopkins Hosp. 1917;28:159.
7. Mennell JB. The Science and Art of Joint Manipulation: The Spinal Column. 2nd ed. London, England: J & A Churchill Ltd; 1952:90.
8. Norman GF. Sacroiliac disease and its relationship to lower abdominal pain. Am J Surg. 1968;116:h54–h46.
9. Rauber-Kopsch F: Lehrbuch and Atlas der Anatomie des Menschen. Edited by Kopsch F, Thierme G, Leipzig 1940–43.
    10. DonTigny RL. Measuring PSIS movement. Clin Manag. 1990;10:43–44.

      abdominal pain; idiopathic scoliosis; immediate relief of common low back pain; low back pain; pelvic biomechanics; sacroiliac pathology; sciatic neuritis

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