Whether we like it or not, the times are "a changin'" and the health care consumer is demanding more while insurance reimbursement is decreasing. Expanding our clinical competence by adding more tools to our toolbox may be the best remedy to not only meet these challenges and strengthen our profession, but also to provide long-term satisfaction to our careers. The model for health care is evolving and "lifestyle enhancement" will be the focus, especially for an aging population.
One of those many tools comes from the Postural Restoration Institute (PRI). The institute's work on myokinematics is the study of movement regarding position of muscles and their influence on structure. "Myokinematic restoration" appears to be an especially powerful tool for the treatment of pathomechanics, especially in the lumbopelvic-femoral region.1
In part 1 of this series, I discussed the many asymmetries we are born with as human beings; asymmetries that affect the neuromusculoskeletal, cardiovascular and lymph systems. It is a marvel that we are born with a compensatory system that (most of the time) self-corrects or maintains a close enough balance that we don't notice until pain, obvious dysfunction or disease develops if and when those asymmetries become excessive.
As with any skeletal structure, ligaments play a pivotal role in the position of the lumbopelvic-femoral region. However, it is the relationship of muscles to repositioning, retraining and restoring function that brings us to this discussion regarding the biomechanics of the pelvis and spine.
Influences on Gait
One of the most important considerations with pelvic position and alignment is the position of the acetabulum over the femur.2We usually think of a femur swinging underneath our pelvis when we walk; or we think of range of motion of the femur in terms of seated internal or external rotation, as measured with a goniometer.
A key concept to understand is that the position of the pelvis actually dictates movement of the acetabulum over the femur during gait cycles. This movement positioning is called acetabular-femoral or "AF." Conversely, if we are talking about the femur moving in an acetabulum that is fixed or stable, then it is femoral-acetabular or "FA."2
For the sake of description, stop reading for a moment and put your hands out in front of you, on your lap. Make the shape of a pelvis with your hands and move them in opposite directions, as if you were walking. With hands in a somewhat neutral position and thumbs up, each wrist should be moving in opposite directions just a bit to simulate movement of each inominate with the acetabulum over the head of the femurs (ulnar deviation on one side of the wrists and radial deviation on the other). This is AF movement.
As mentioned in part 1, most of us have a dominate left anterior-interior chain pattern or left AIC, as described by Ron Hruska, PT, the founder of PRI. This chain of muscles typically has too much activation or "tone," and has a major role in creating a flexed hip on the left, extended hip on the right and "rotated to the right pelvic" girdle or a right orientation.
So, just move your left elbow out to the side a bit, and move your left hand slightly forward and angled to the right with both hands moving in a clockwise direction slightly, as if you are looking straight down at them. This is rotation in the transverse plane that is characteristic of a left AIC pattern.4
The sacrum and lumbar spine develop torsion and a right orientation as well, but then as compensation, the thorax and shoulders can develop rotation to the left, creating rotational and compressive forces in the spine. Often a right SI distraction or gap will form on the superior portion of that joint, causing the common "top-of-the-butt-on-the-right-side" pain as one example of symptoms caused by this position.3
Now remember that "AF" position is relative to the pelvis, and that there will be an internally rotated femur on the right and an externally rotated femur on the left relative to each inominate. With the left AIC pattern, we are stuck in "AF-ER" on the left side and "AF-IR" on the right side. As a result, we are also stuck in a right mid-stance phase. This asymmetrical compensatory pattern occurs because of the inability of muscles to maintain the pelvis in a neutral and balanced position.
Remember that if we are looking down at our hands, we want them to be symmetrical, with the ability to move AF-ER and AF-IR on both sides equally. However, our first priority is to achieve more AF-IR on the left side and more AF-ER on the right to overcome this dysfunctional pattern.3
What makes symmetrical IR during gait so important? Our propulsive power really comes from the ability to externally rotate and extend the hip effectively, but this doesn't occur without adequate symmetrical internal rotation. As James Anderson, PT, states, "You must first load (IR, or internally rotate) before you can explode (ER, external rotate) the hip."
Muscles and Pelvic Position
In this brief overview, we need to look at a few of the major muscle players and their role in dictating the position of our pelvis. On the left side there is an overactive iliacus / psoas that contributes to pulling us into flexion and external rotation. The TFL is short and strong, and is compromising the left "anterior" glute medius' ability to internally rotate the femur. (Remember, we are trying to get IR back on the left side.) The rest of the muscles in that chain, including the vastus lateralis and biceps femoris, are overactive as well.4
When the left anterior glute medius becomes long and weak due to pelvic AIC positioning, it has a hard time trying to get the left femur into internal rotation. The posterior part of the glute medius is firing mightily, creating abduction and external rotation. This is fine for the right side, but not so much for this left side! Again, we need to get into internal rotation on the left and external rotation on the right.5
The "king of the pelvic floor and pelvis" is the gluteus maximus, and two of its main roles include hip extension and external rotation. On the left, the extension fibers are long, weak and out of position for optimal extension of the hip. Those fibers need to be shortened and activated; while on the right side, the external rotation fibers of the glute are long and weak, and need to be shortened and activated for optimal pelvic position from that side.5
There are two functions of the adductors we have to consider. The adductor magnus and longus actually externally rotate as well as adduct, but it is the ischiocondylar portion of the adductor magnus that we want to focus on, because that distal attachment is the portion that is concerned with internal rotation on the left side. Remember, "IR" on the left is hard to come by with a strong left AIC pattern. It's key to remember to feed internal rotation on the left and external rotation on the right to correct this pattern.4-5
Helping control the pelvis requires controlling the obturator foramina, because that is where the obturator internus and externus live as they attach to the femur. These muscles have great control and influence on the position of the pelvis because they control the orientation of the obturator foramina. The obturator internus and externus have "hole control" or dictate the position of the obturator foramina, which controls and maintains position of the pelvis, especially during walking or running.5
Included in this asymmetry, the hamstrings on the left will be long and weak, with longer attachment points, because the position of the left hemi-pelvis is in flexed position. How often do you run into a tight left hamstring and try to stretch through it? Could it be that it is already stretched, but because of pelvic positioning, the attachment points are lengthened relative to the right? So, the right-side musculature will have opposite muscular length and activation to the left, contributing to a compensatory dysfunction that feeds into the entire asymmetrical positioning of the pelvis.
The key point to keep in mind here is that whatever side is long, weak, short or strong will be the opposite on the other side. The trick is understanding that the position and length of muscles on each side will determine what is required to correct the pelvis and help maintain your chiropractic adjustments far longer. In addition, your patient becomes an active participant instead of a passive recipient of care. This type of patient / doctor cooperation makes your treatment and craft much more powerful and effective, and only contributes to your healing philosophy.
Chiropractic icons like Dr. Clarence Gonstead and Dr. Major DeJarnette were very observant when it came to pelvic positioning. Dr. Gonstead came up with listings; a system for defining pelvic alignment and a logical formula for correcting misalignment or subluxation. Dr. DeJarnette, a chiropractor and an osteopath, saw the relationship between the cranium and sacrum, and that each affect the entire body through the kinetic chain. Both doctors developed very effective techniques that we still use today and can be built upon with new discoveries in today's emerging fields of pelvic and spinal functional biomechanics. (I utilize both of these techniques, as well as the latest approaches to spinal biomechanics including PRI strategies.)
References
- Postural Restoration Institute (PRI). Myokinematic Restoration. Home study course; James Anderson, PT, instructor.
- PRI, Op Cit, p.p. 4-8.
- PRI, Op Cit, p.p. 8-12.
- "The Left Anterior Interior Chain Pattern." PRI Myokinematic Restoration. Home study course: p. vii.
- PRI, Op Cit, p.p. 18-20.
Part 3 of "Unlocking Secrets of the Pelvis" will explore several tests to determine the position of the inominate bones in relation to the femurs; and how breathing affects not only the entire kinetic chain, but the autonomic nervous system as well.
