The Pain in the Low Back Often Begins in the Foot, or Is It in Your Head? What Do You Treat?

By Keith Innes

Ignoring the effects of the lower extremity on the functional capacity of the low back can mean missing the primary cause of the patients pain, and unnecessary treatment to another area. Following the kinetic chain to locate the pain generator is indeed a logical process, however it demands a significant amount of knowledge of the functional anatomy, arthrology and biomechanics (both normal and compensatory) of the lower limb and lumbopelvic regions, and a comprehensive grasp on the ascending and descending pathways of our nervous systems.

Chiropractic has always taken x-rays in a weightbearing position so that one can get an overall postural view of the patient, however the examination is for the most part a nonweightbearing situation, either supine or prone. This instantaneous "snapshot" of bony alignment may not reflect the functional positioning of the patient during propagation of the greatest forces causing deformities/malfunction during gait, or any other life-like situation. This is followed by an adjustment in yet another postural situation, most likely in an position which by no means correlates to or represents a real life situation.

The human biomechanical motion machine is not a static device, rather it is dynamic in every way and susceptible to gravity and ground reactive forces throughout our daily lives. To consider treatment of the low back in the absence of lower extremity examination and differential examination is illogical and unfair to our patients. Chiropractors have always suggested that we treat the cause. I totally agree, but what is really the cause? Always the spine? I do not think so!

Let me have you consider the following. In the journal of the lower extremity movement (Biomechanics, 2(9), Oct. 1995) there appeared an article, "Tracing the Pain." Do your patients complain of low back pain? Take a look at their legs and feet. Now you might be thinking that this is an insignificant article that just happened by chance. Let me assure you that it is not by chance, but by very exact design that others are looking to the cause of low back pain and finding the primary subluxation in the lower extremity. Remember what Dr. C. S. Gonstead stated: "Find it, accept it where you find it, fix it, and leave it alone." But you need to be competent to find it before the others are applicable. Diagnosing is just a matter of applying one's knowledge of anatomy, including neuroanatomy.

Gait is a very difficult concept to understand, but is very important to chiropractic. Gait is either gross gait or gait as it pertains to the individual joints. Gait from the Joint Point of View

At heel rocker/strike the calcaneus is inverted and the pre-tibial muscles are concentrically contracted. To keep the foot dorsiflexed the tibialis anterior muscle contracts just prior to heel strike. Recall that the this muscle attaches to the medial side of the first metatarsal, where it becomes intimately blended in with the fibers of the peroneus longus muscle. Together they form the longitudinal muscle-tendon-fascia sling which functions dynamically along with the inferior dropping fibula. The foot is lowered to the ground and is under the control of the eccentric contraction of the pre-tibial muscles. At this point the fibula drops inferior and loads the long head of the biceps femoris, the ipsilateral sacrotuberous ligament, the ipsilateral multifidus, the contralateral gluteus maximus, thoracolumbar fascia, and latissimus dorsi. Form and subsequent force closure of the iliosacral joint, on the side of stance leg, now initiates sacroiliac motion on an oblique axis. The tibia translates anterior in response to the body's line of forward progression.

Working in concert with concentric contraction of the pre-tibial muscles, the tibia translates over the talocrural joint. This position is known as midfoot rocker. The lower limb internally rotates throughout the contact phase causing the talus to internally rotate, plantar flex and adduct, thus initiating movement of the posterior portion of the subtalar joint. The subtalar joint is made up of the posterior, middle and anterior portions. The posterior has its own joint capsule and functions separately from the middle and anterior joints who share a common joint capsule with the navicular forming a functional joint -- the talocalcaneonavicular joint. The facet on the posterior calcaneus slides medially as the calcaneus moves to a position of a (right foot) counter clockwise motion in a sagittal plane. Simply put, the direction of slide of the articulation is opposite to the direction of movement of the calcaneus.

The middle and anterior portions of the subtalar joint move in the same direction as the calcaneus and, along with the navicular, plantar flex. The navicular also adducts at this point, as the midfoot and forefoot in the open kinetic chain position tends to follow the rear foot. This completion of subtalar pronation results in a simultaneous parallelism of the axes of the transverse tarsal joint to allow for pliant adaptation for accommodation to uneven terrain. This is known as mid foot pronation. The first ray complex (the first metatarsal and its associated cuneiform) follows the midfoot and pronates as well. This rotation reorients the first metatarsophalangeal joint axis obliquely, promoting toe pronation and the development of hallux valgus. Great toe pronation in hallux valgus is compensatory to eversion at the first metatarsocuneiform joint. Recalling that as the metatarsophalangeal joint pronates it also, due to the shape of its articulation, moves towards the midline of the now weightbearing forefoot. This results in a functional hallux valgus formation during the gait cycle. The tibia is between the necessary 10-20 degrees of anterior movement, and late mid-stance phase of gait is complete.

As the body moves anterior in a line of progression a number of events occur almost simultaneously: 

• The contralateral hip moves forward, initiating internal or medial rotation of the femur; this in turn causes the stance phase leg to externally rotate.
  
  
• The externally rotating leg causes the tibia, talus, and subtalar joints to supinate.
  
  
• Ground reaction forces anterior to the metatarsal heads dorsiflexes the first toe, creating tension in the plantar aponeurosis. This pulls the great toe back, producing a reaction force at the first metatarsophalangeal joint, and a plantar flexion moment around the joints of the first ray complex.
  
  
• Tension in the aponeurosis produces a supinatory movement around the subtalar joints, posterior and TCN.
  
  
• The loaded metatarsal slides back over the sesamoids, assisted by contraction of the peroneus longus muscle which inserts into its base.
  
  
• Eccentric contraction of the flexor digitorum longus helps to stabilize the first ray and medial arch.
  
  
• The contraction of the peroneus longus, in addition to the above, also causes a convergence of the transverse tarsal joints, calcaneocuboid and talonavicular, which converts this articulation into a rigid lever for impending toe off.
  
  
• Toe off is now complete and the procedure repeats itself.

In a previous article of mine, "The Back Force Transmission System," it was pointed out how critical the function of the lower limb was to the harmonious and dynamic functioning of the pelvis and spinal articulations.

The foot and gait are indeed complicated structures. To remain at the forefront of health care DCs need to understand this and much more. It should also be appreciated that higher centers (i.e., neocortex and thalamus to name but two) may predispose one to spinal and lower limb dysfunction. Information about these topics will follow in future columns.

The pain in the low back can start in the foot or it may be in your head. So what do you treat? Clearly from the above it can be seen that the case history and the examination, combined with a thorough knowledge of all aspects of anatomy and neurology, will lead you to the answer.

Keith Innes, DC
Ontario, Canada