Explore the Key Role of Pedal Stability in Optimal Kinetic Chain Function
Help your patients maintain proper cervical posture by adding this important information to your protocol.
In this issue... The body is an interconnected chain of segments, with its base in the feet. Pedal instability may contribute to observable postural distortions as far up the chain as the cervical spine. For the most effective adjustments and optimal treatment options, examining for and treating any detectable foot conditions should be an integral part of pain management.
Ideal cervical spine posture in the standing position requires the coordination of skeletal structure, soft tissue integrity, and neurological control to resist adverse gravitational loading forces. An often overlooked factor of the above requirements is the role that pedal stability can play in the maintenance of proper cervical posture. Faulty foot biomechanics can have a negative impact on all supporting joints above the foot/ankle complex. In particular, an unbalanced pedal foundation may contribute to a postural anterior translation in the head and neck over time. For maximum effectiveness, the healthcare professional seeking to treat a postural deviation in the cervical spine needs to evaluate the potential involvement of the pedal foundation, and to correct postural foot problems.
The development of the unique human bipedal upright posture and resultant movement created a more optimum and functional form of ambulation, but with it developed a different variety of potential stressful forces on the connective tissues of the body. The original biomechanical human profile, directed by survival, was primarily a dynamic one. “The ligamentous skeleton is built for mobility rather than stability.”1 Yet over time, human beings have assumed a less consistent, less dynamically optimum biomechanical physical stature on a daily basis. “Compared to primitive man living an outdoor life, civilized man has become a standing-around and a sitting-down animal rather than a running-around one.”2
The relatively sedentary lifestyles and/or altered/compromising postures that a vast majority of human beings assume on a daily basis have placed maladapted strains on the ligaments, tendons, muscle fibers, fasciae, cartilage, and bone in an attempt to maintain equilibrium of the mechanical body. Cailliet reports that many “painful disabling conditions of the soft tissues of the musculoskeletal system are directly or indirectly related to posture in standing, walking, moving, lying, sitting, bending, or lifting.”3 It has been found that up to one third of workers in the United States are required to perform manual activities on a daily basis that are damaging to the musculoskeletal system.1 Many times these potentially harmful tasks involve stationary imbalanced postures as well as dynamically uncoordinated movements.
For preventative healthcare, or specifically neuromusculoskeletal health maintenance, it is basic and imperative that health care specialists take into account an evaluation of an individual's habitual posture and its potential role in pain and disability and include it in their exam. If postural faults were only of aesthetic consequence, the concern about them might be limited to appearance. But this does not appear to be the case, in that postural abnormalities may cause discomfort, pain, or deformity.3,5,6
The Biostatic Chain
During walking and running, the spine is one link in a biomechanical Kinetic Chain, where movement at one joint influences movement at other joints in the chain.7 This concept of a chain also applies to the body in a motionless, standing posture; however, the terms biomechanical static chain or biostatic chain are more appropriate, since directed movement is not involved. In either case, the chain extends from the feet through the ankle, tibia, knee, femur, hip joint, pelvis, and spine.
The biostatic chain depends upon the balance of body alignment and muscle restraining activity at each joint against gravitational pull downward. Passive stability is achieved when the center of gravity of each segment is aligned directly over the center of the supporting joint (see Fig. 1). When the body is erect and weight is evenly distributed between the feet, there are minimal demands for muscle action, because there is no forward motion. While in theory, stability of the biostatic chain should be realized without any muscle action at all, the fact that none of the supporting joints (pelvis downward through feet) are locked means that the slightest sway (the beating of the heart, for example) can create an unstable alignment.1 Therefore, postural balance means a continuous involvement of the supporting skeletal structure and muscles.
Pedal Foundation Deficit
In ideal standing posture, the feet evert to form an angle of 30 degrees, and a plumb line dropped from the sacral promontory falls midway between the feet onto a line between the navicular bones (see Fig. 2).8
Pronation occurs when the superior aspect of the calcaneus tilts and rolls inward, bringing the talus with it. This releases the navicular from its arthrodial articulation with the talus and jeopardizes the medial longitudinal arch. When collapsed, it causes an anterior shift in weightbearing, and begins a serial distortion that may extend to the occiput (see Fig. 3).9
Because pronation involves the talus, it can draw the adjacent tibia into rotation. The movement extends further to the femur, bringing the greater trochanter forward and out. The piriformis muscle at the apex of the trochanter is then subjected to a windlass-type stretch. Due to its connection with second, third and fourth sacral segments, the sacrum at its articulation with the ilium on the involved side may be pulled into a subluxated anterior and inferior position.
When this occurs, the gluteus maximus muscle compensates by contracting to resist the downward and forward disposition of the pelvis. At its origin on the posterior third of the iliac crest, the gluteus maximus contraction may force the ilia portion of the innominate to rotate posteriorly. Thus begins a typical basic distortion.
Likewise, with the sacrum in an anterior and inferior position, the fifth lumbar vertebrate is mobile. Following Lovett's Law, it will rotate toward the low side and introduce a functional scoliosis.
According to Free, the trapezius muscle “may tighten on the same side as the hypertonic hamstring, creating an inferior occiput and an atlas laterality. Subluxations may occur at the atlanto-occipital or the atlanto-axial area, with cervical pain on the side of the tight hamstring. If this cervical compensation occurs, the patient will have pain on the entire side (cervical, thoracic, lumbar) and many times the leg and arm.”10 Porterfield writes that “the cervical spine may be only one component of neck pain complaints. Structures related to the upper extremity and head often are involved with the painful syndrome, and an examination of these structures reveals alteration in function.”1
Clinical evaluation of the standing posture using relatively low-tech tools has been confirmed as valid and reliable by several studies.12,13,14 The original device used to evaluate posture was the plumb line, which served as a reference line for the effects of gravity on body alignment.
A valuable procedure in postural evaluation is the assessment in the frontal and sagittal planes of the balance and alignment of the three major regional masses of the body (cervical, torso, pelvis), and their relationship to their base of support— the feet and legs. This method permits a rapid yet standardized determination of postural deviation from the optimal alignment and can be used in prescribing specific corrective exercises.
When assessing cervical postural distortions in the sagittal plane, the most common is identified as anterior translation. Translation is the motion of a rigid body in which a straight line in the body always remains parallel to itself. “For example, if a boat is pushed smoothly in a straight line from position 1 to position 2 without pitching or rolling, it moves in pure translation” (see Fig. 4).16
In anterior translation, the ear is forward of the AC joint and the bite line is level, creating the so called “dowager's hump”.17 In addition to the forward head, the evaluating clinician may also note a distortion of normal cervical lordosis, round shoulders, internally rotated humerus, and kyphotic posture. These deviations have been identified as “mainly a result of the integrity of the abdominal wall and hip joints” (see Fig. 5).
As has been previously discussed, the spine is one link in a chain, with the feet as the base. Lack of stability in the pedal foundation can lead to serial distortions and muscular stretching all the way up the spine. With foot pronation and the associated collapse of the anterior transverse arch, the base point of the body's center of gravity shifts forward. This shifting causes a pelvic translation, which in turn produces a thoracic extension. At this point the head attempts to maintain its position over the vertical center of gravity, and therefore slides into anterior translation. The body's overall stabilization efficiency is greatly reduced, and it must work harder to maintain a standing posture. Cailliet concluded that for every one inch of anterior translation, there is a ten-fold increase in muscular effort on the part of the supporting muscles of the cervical spine. This inefficiency results in a constant firing of these muscles.18
Given the above sequence of events, it is not surprising that there are literally hundreds of clinical observations which suggest that a mutually detectable relationship appears to exist between a cervical anterior translation and a deviated pedal foundation (pronated feet). Although quantifiable literature on this subject is lacking at present, clinical observations of this phenomenon are common. Therefore, in order to provide your patient with optimal balance and stability, it is critical that you evaluate and treat all the areas involved - feet, pelvis, torso, and cervical spine.
Treatment of cervical anterior translation requires manipulation, the prescription of the appropriate conditioning exercise regimen, and if indicated, corrective orthotic support. Often, both muscle and joint dysfunction require correction19, and appropriate strength should be developed to help minimize the potential of future injury.20
For isotonic exercise of the cervical spine, the NECKSYS® Cervical Rehab System is a unique combination of a versatile, simple-to-use neck exerciser, cervical collar, and a series of biomechanical exercises. In minutes, you can instruct the patient to use the System and perform the prescribed exercise of posterior translation from home (see Fig. 6). Combining the chiropractic adjustment with the NECKSYS exercise will speed recovery due to the benefits of the NECKSYS Home Care System.
As mentioned in Porterfield, cervical anterior translation can be linked to weakness in the thoracic spine.11 The BACKSYS® System provides an easy-to use, effective way to condition and strengthen back muscles affected by injury, illness, or postural deficits. In the case of thoracic extension, the appropriate exercise would be thoracic flexion.21
In the case of anterior pelvic translation, the corrective exercise with the BACKSYS is posterior pelvic translation, (see Fig. 7)
The NECKSYS® and BACKSYS® Systems are based on postural distortions and the proper corrective exercise as published by the Chiropractic Rehab Association and developed by Donald Harrison, M.S., D.C., which allow patients to perform very posture-specific asymmetric exercise maneuvers against resistance.13 The result is a stretching of shortened connective tissues while strengthening and re-training imbalanced spinal support muscles.
The Crucial Role of Custom Orthotics
Custom flexible orthotics that support all three arches of the feet are of special value in cervical anterior translation cases where foot pronation and arch ligament laxity have been observed. A flexible, custom-made orthotic addresses the excessive pronation and provides support for collapsed structures in the feet, and should be added to every patient’s treatment plan.
The Foot Levelers Rehab Website - packed with FREE tools and resources to help you provide the most effective rehab treatments
Explore orthotic and rehab tool recommendations for common conditions, rehab exercise videos, helpful articles, and much more, visit footlevelers.com/rehabilitation.
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Doctor-reviewed by Christine Foss, DC, MD, MS. Ed, ATC, DACBSP, DACRB, ICSC