One of the most common foot disorders is the pronated foot. It can be used as an example to illustrate how alterations in its function can be followed by a series of biomechanical changes that produce a wide variety of signs and symptoms through the interrelated structures and systems of the body.
The pronated foot presents with multiple site fixations that could include the posterior subtalar joint, the calcaneotalonavicular complex, the cuboid, mortice joint and the first ray. Weight will be borne on the medial structures and there will be an internal rotation of the entire lower extremity accompanied by an increase of the normal anterior pelvic inclination. With internal rotation of the femur, the greater trochanter moves anterior and the lesser trochanter moves posterior. These two bony processes are traction processes, the former for attachment of gluteal muscles, and the latter for the tendon of the iliopsoas. In the case of the internally rotated lower extremity, the tendon of the iliopsoas is tensed as it passes to the tractionation. It is worth noting that this increased tension may cause pain over the anterior aspect of the hip joint from which the tendon is separated by a bursa.
If the anterior pelvic inclination is increased, the posterior portion will be elevated, accompanied by an abnormal stretching and tension of the hamstring muscles. In this group the biceps femorus holds the greatest clinical interest. Although the long head originates from the ischium many of its fibers are directly continuous with the sacrotuberous ligament. Traction of this muscle makes tense the entire ligament and the coccyx is therefore made to move on the sacrum. Clinical importance of this relationship is significant. Just anterior to the coccyx is the ganglion impar of the sympathetic trunk and the anorectal region with its visceral branches to the hypogastric and pelvic plexuses. Tensions of this ligament should be kept in mind when coccygodinia and the wide variety of perinopelvic disorders that may well be associated with pelvic imbalance are encountered.
Elevation of the posterior part of the pelvis, coupled with the forward position of the greater trochanter, is accompanied by increased tonicity of the piriformus muscle, upon which the sacral plexus of nerves lies within the pelvis. The above situations of pelvic dysfunction may give rise to a sciatic pain that is secondary to the postural change. At this point, I would like to remind the reader that the cause of this scenario is the subtalar joint pronation; it is this that must be adjusted to fix the postural abnormalities and structural compensations.
Increased lumbosacral junction angle is a common finding in those patients with pronation of the foot and associated internal rotation of the lower extremity. The center of gravity falls anterior to its normal position and a shearing force takes place at the L-S junction. Strain of the iliolumbar ligament usually results and a lumbosacral junction subluxation is produced.
Unleveling of the sacral base must be followed by other changes since it is the body's nature to compensate for structural imbalance. The groundwork has now been laid for extensive spinal pathology from sacrum to occiput.
The pelvis has been mentioned as the junction between the mobile spinal segments and the moveable lower extremities. It is therefore important to remember that not only are the somatic structures involved but also the genitourinary and gastrointestinal systems as well.
The soft tissues, the muscles, fascia, and ligaments functioning under abnormal stress and strain, in an effort to keep the body in as near normal a position as is possible, are usually contracted, sometimes stretched, and sometimes shortened. Generally speaking, the muscles, the origins of which have been brought closer to the insertions due to the postural change, are the ones that will undergo shortening. The opposite relations produce stretching: both may be painful upon palpation. These areas are found in relation to the postural groups concerned. The principal ones are: (1) the plantar fascia and muscles; (2) the gastrocnemius and soleus forming the calf of the leg, where the most tender point is at the site of injunction of the tendinous portions of the two muscles at the middle of the calf; (3) the iliotibial band of the fascia lata on the lateral aspect of the thigh where the tensor fascia lata and the gluteus maximus enter about its middle, the origin of the satorius at and below the anterior superior iliac spine, a muscle that undergoes shortening in this condition and which helps to maintain the anterior inclination of the pelvis; (4) the fleshy origin of the gluteal muscles associated with the dorsum illi; and (5) the area over the extrapelvic portion of the piriformis muscle. The last named point requires definite location which can be reached midway on a line drawn from the tuberosity of the ischium to the greater trochanter of the femur. At this point where the sciatic nerve passes downward into the thigh and immediately above it, the painful piriformis spasm can be elicited.
So what do you treat? Obviously the foot, but more specifically the subtalar joint. The subtalar joint must be examined for joint play motions in both a closed kinetic chain and an open kinetic chain as talar motion is ONLY a function of the weight bearing foot. MPI's new E1 Lower Extremity seminar details many new examination and adjustment procedures that will enable you to become a more proficient doctor when it comes to locating the CAUSE of your patient's low back pain.
Keith Innes,
DC Scarborough, Ontario
Canada
Editor's note: Dr. Innes will be conducting his next MPI seminars October 2-3 ("Upper Extremities") in Toronto, Canada; Oct. 9-10 ("Lower Extremities") in Chicago, Illinois; and Oct. 16-17 ("Full Spine") in St. Louis, Missouri. You may register by dialing 1 (800) 359-2289.
