by Kim D. Christensen, DC, DACRB, CCSP

Flatfoot is defined as a lack of the medial longitudinal arch of the foot.  Adults with flat feet demonstrate several biomechanical inefficiencies in the foot and ankle, as well as a variety of gait abnormalities.  The development of clinical problems is dependent on the levels of activity and the amount of repetitive stress the feet must endure.  The average person spends four hours each day on their feet, and takes between 8,000 and 10,000 steps every day.  In some jobs and many sports, these amounts are more than doubled.  During an average day, the feet support a combined force equivalent to several hundred tons.  In addition to carrying the weight of the body, each foot acts as a shock absorber and a lever to propel the leg and body forward, and it serves to balance and adjust the body to uneven surfaces.  The various problems associated with flatfoot can interfere significantly with normal daily activities, as well as limiting participation in recreational and competitive sports.  Flat feet are due to either a loss of the normal arch due to breakdown of the supportive collagen structures, or a lack of development of a normal arch in the first place. 

Congenital Flatfoot

Until about the age of 2 years, infants have flat feet, due to the presence of a large medial fat pad, and incomplete development of the foot structures. (1)  As children begin to walk and spend more time on their feet, this fat pad slowly decreases, resulting in a noticeable medial longitudinal arch. (2)  A study of the developing arch in children has confirmed that 28 to 35% of school children have an apparent flatfoot deformity, but 80% of those are classified as “mild.” (3)  Follow-up evaluations have determined that 90% of these children will have normal arches by the age of 10 years. (4)  The remainder never develop an arch, and are considered to have a “congenital flatfoot.”

Acquired Flatfoot

As adults, some of those who did develop a normal arch gradually lose it.  This occurs secondary to a breakdown of the normally strong and dense connective tissues of the foot.  It is the ligaments and connective tissues that support the medial longitudinal arch, (5) and not muscular strength. (6)  In fact, normal alignment depends on a complex arrangement of dense collagenous fibers, and no single structure provides all of the support. (7)  Problems with this arch will develop when these supportive tissues are put under excessive stress.  This can be either from high loads for sudden, brief periods, or from more moderate, but repetitive stresses over longer periods, resulting in an “acquired flatfoot.”

Rigid Flatfoot

The overwhelming majority of flat feet are considered “flexible,” and will respond well to external support.  In some cases, however, the arch never develops due to a bony abnormality (most commonly a tarsal coalition).  This results in a “rigid” flatfoot, which will can be greatly aggravated by attempts to provide external support with inserts and orthotics.  Differentiation is important, but can be easily done during the examination.  If an arch is present when the patient is sitting with the foot dangling, or when standing up on the toes (toe-raise test), then the flatfoot is “supple and is correctable with an arch support.” (8)  If the foot remains flat and rigid during this test, any attempt to lift up or support the arch can be painful, and corrective orthotics generally are avoided.  Evaluation by a foot specialist is usually necessary to determine the underlying cause of a rigid flatfoot.  Treatment may consist of accommodative orthotics and/or surgery.

Associated Terminology

Two descriptive terms are often used interchangeably with flatfoot, and can contribute to confusion.  Pes planus is the more technical term that represents a flattening of the longitudinal arch; the arch is lower than established normal parameters when standing, especially on radiographic evaluation. (9)  Hyperpronation (or excessive pronation) refers to excessive medial deviation of the talus during gait, primarily during the stance phase of gait. (10)  Both of these problems are found in patients with flexible flatfoot, and will interfere with lower extremity biomechanics.  An extensive list of the varied symptom complexes and health problems caused by flexible flatfeet has been compiled by Dr. Yale (Table 1). (11)

Energy Cost / Athletic Performance

An interesting study assessed the effects of arch supports on oxygen consumption in 20 subjects with flat feet who complained of fatigue and “weariness.” (12)  The participants were between 18 and 38 years old, and had no specific foot symptoms.  Their heart rates, blood pressures, and walking oxygen consumption were measured on a treadmill – first without, and then with arch-supporting orthotics.  The results demonstrated that use of the orthotics significantly improved their gait efficiency, and decreased their oxygen consumption during normal walking.  These responses can be extrapolated to athletic performance.  In fact, it has long been observed that a flat foot, and hyperpronation, in particular, can interfere with performance in a number of sports. (13)

Support From Orthotics

In order to improve the biomechanics of the foot and provide permanent support for the medial longitudinal arch, most patients will need custom-fitted orthotics.  Active patients generally benefit from flexible orthotics which are most beneficial for athletes and workers who must be on their feet for many hours each day.  A recently published study found that custom-made flexible orthotics cast in a weight-bearing position significantly improved the alignment of the foot and increased the medial longitudinal arch when standing. (14)  The materials and fit of an orthotic are critical, since support is needed for all three arches of the foot, along with cushioning and shock absorption in a comfortable insert.  Additional padding under the forefoot is a recent addition that appears to be very helpful.

Conclusion

Flatfoot in adults may be congenital (the medial arch never developed), or acquired (the connective tissues no longer can support the medial arch).  A rigid flatfoot is due to an osseous deformity, such as a tarsal coalition.  As long as a flat foot is flexible, orthotic support for the medial arch can improve foot and ankle biomechanics, decreasing hyperpronation and enhancing performance in daily activities and during sports.

References

1. Magee DJ. Orthopedic Physical Assessment. Philadelphia: WB Saunders; 1987, 329.

2. Kemp HC. Current Pediatric Diagnosis and Treatment. Norwalk: Appleton and Lange; 1984, 614.

3. Notari MA. A study of the incidence of pedal pathology in children. J Am Podiatr Med Assn 1988; 78:518-521.

4. Wetton EA. The Harris and Beath footprint: interpretation and clinical value. Foot & Ankle 1992; 13:462-468.

5. Huang CK, et al. Biomechanical evaluation of longitudinal arch stability. Foot & Ankle 1993; 14:353-357.

6. Basmajian JV, Stecko G. The role of muscles in arch support of the foot. J Bone Joint Surg 1963; 45A:1184-1190.

7. Kitaoka HB, et al. Stability of the arch of the foot. Foot & Ankle 1997; 18:644-648.

8. Hoppenfeld S. Physical Examination of the Spine and Extremities. New York: Appleton-Century-Crofts; 1976, 232.

9. Forrester D, Kerr R, Kricun ME. Imaging of the Foot and Ankle. Gaithersburg: Aspen Pubs; 1988.

10. Gould N. Evaluation of hyperpronation and pes planus in adults. Clin Orthop Rel Res 1983; 181:37-45.

11. Yale JF. The conservative treatment of adult flexible flatfoot. Clin Pod Med and Surg 1989; 6:555-660.

12. Otman S, et al. Energy cost of walking with flat feet. Prosthets and Orthots Intl 1988; 12:73-76.

13. Subotnick SI. Sports Medicine of the Lower Extremity. New York: Churchill Livingstone; 1989, 159.

14. Kuhn DR, et al. Radiographic evaluation of weight-bearing orthotics and their effect on flexible pes planus. J Manip Physiol Ther 1999; 22:221-226.

[Table 1]

Improving Proprioceptive Balance with Orthotic Support

by Kim D. Christensen, DC, DACRB, CCSP

Recently published research has shown that custom orthotic support can help improve structural alignment (1), balance (2), gait (3), and athletic performance. (4)  This is quite an extensive list of benefits.  How can all of these claims be justified from the use of a single adjunctive therapy?

There is a reason so many changes (both in physical function and in symptoms) are reported with  the use of custom-fitted orthotics.  This large universe of improvements is due primarily to the sense of proprioception -- one of the most important neurological systems of the body.  A quick review of the mechanisms and components of proprioception will help us comprehend how patients can demonstrate such a large variety of improvements.  Being able to explain this to patients (using simpler terms, of course) will help them understand the reasons you are recommending they wear in-shoe orthotics.

Specialized Sensory Organs

Proprioception is defined as “sensing the motion and position of the body”. (5)  Specialized nerve endings are present throughout the soft tissues of the musculoskeletal system which interact with the central nervous system and coordinate our body movements, our postural alignment, and our balance.  Athletic activities, in particular, rely on this delicately controlled and finely-tuned system of receptors and feedback loops, as well as the validity of the information which is sent into the spinal cord.  This coordination normally allows for appropriate motor responses -- and in some special cases, artistic physical performances.

Proprioceptive sensory organs are found in two distinct groups which are located in either muscles and tendons, or within the connective tissues (ligaments and capsules) of joints (Table 1).  These specialized nerve fibers provide information regarding the status and function of the musculoskeletal system with a constant flow of information to the spinal cord, the cerebellum, and the brain. 

When there is a communications breakdown, or when improper information is supplied by one or more of these sensors, efficiency of movement decreases.  This is harmful and possibly injurious to the muscles and joints, and results in problems with postural coordination and/or joint alignment.  Beyond being just an annoyance, faulty coordination or misalignments can also be the source of chronic, unresolving pain.

Location of Nerve Endings

The most important sensory nerve endings for controlling the muscular system are the muscle spindle fibers and the Golgi tendon organs.  Muscle spindle fibers are found interspersed within the contractile fibers of all skeletal muscles, with the highest concentration in the central portion (belly) of each muscle.  Muscle spindles respond to changes in the length of muscles.  A complex circuitry of these nerve endings, with interconnections in the dorsal horn of the spinal cord, maintains muscle tone and, most importantly, the appropriate tension in the muscles on opposite sides of each joint.  Without this basic “wiring”, proper joint alignment can’t be maintained, and relaxed, upright posture is almost impossible.

Golgi tendon organs are located in the junctions of muscles and their tendons.  These protective nerve endings exert a powerful inhibitory effect on contraction of the muscle fibers.  They are stimulated by strong stretching of the muscle/tendon junction (as when the muscle fibers are contracting too strongly).  Golgi tendon organs transmit their information to the spinal cord and cerebellum through large, rapidly conducting nerve fibers, and they can rapidly inhibit a muscle contraction in order to protect the tendon.

Joint Mechanoreceptors

Surrounding and protecting all joints are tough, fibrous tissues which contain a variety of sensory nerve endings.  The input from these specialized sensors keeps the nervous system informed as to the location of the joint, and also the degree of stretch, compression, tension, acceleration, and rotation. (6)  These joint mechanoreceptors are classified by their anatomy and their neurological function. (7)  Type I mechanoreceptors are found in higher densities in the proximal joints.  They sense the position of a joint by signaling the joint angle through normal ranges of motion.  These help determine postural (tonic) muscle contractions.  Type II nerve endings adapt to changes in position, and are most active at onset and termination of movement.  These are more densely distributed though the distal joints, and affect phasic muscle actions.  Type III mechanoreceptors are high threshold, which means they require considerable joint stress at end ranges before firing.  These receptors serve a protective function similar to the Golgi tendon organs.  Type IV receptors are free nerve endings located in the ligaments, joint capsules, and articular fat pads which respond to pain stimulus.  They can generate intense, non-adapting motor responses in all muscles related to a joint, resulting in the protective muscle contractions that restrict joint movement.

Foot Involvement

These six specialized nerve sensors are found throughout the musculoskeletal system, in all skeletal muscles and in every ligament, joint capsule, and articular connective tissue.  With many small joints, lots of connective and articular tissues, and both intrinsic and extrinsic muscles, the feet are particularly well-supplied with proprioceptive nerve endings.  Mechanoreceptors in the joints along with the muscle spindles of the foot muscles are responsible for the positive support reflexes and a variety of automatic reflexive reactions. (8)  These include the flexor/extensor reflex, which converts the lower limb into a firm, yet compliant pillar.  Weightbearing compresses the joints and muscles, evoking reflexive activity in the extensors and inhibition of the flexor muscles. (9)

The first research to demonstrate how altered proprioceptive input predisposes to recurring injuries was performed on patients with chronically sprained ankles. (10) Freeman et al. called this phenomenon “articular de-afferentiation” to recognize the importance of inappropriate afferent signals from injured ankle and foot proprioceptors.  They pointed out that, “Since articular nerve fibers lie in ligaments and capsules, and since these fibers have a lower tensile strength than collagen fibers, it seems inevitable that a traction injury to a ligament or capsule will lead to the rupture of nerve fibers as well as collagen fibers”.  (11)

Conclusion

Except for the spine, the foot is the anatomical region which contains the most proprioceptive sensory receptors, and the foot has very distinctive nerve circuits which must be considered.  Because of the magnitude of sensory input, the feet are frequently involved in clinical conditions which will respond to specific treatment approaches that include the proprioceptors -- such as custom orthotics.  Structural support and shock absorption for the musculoskeletal system is provided by the corrective orthotics, thereby reducing physical stressors on the muscles and joints of the feet, legs, and pelvis.

Greater understanding of the proprioceptive system of sensory receptors in the muscles and joints has enabled us to more accurately assess and treat many complex musculoskeletal problems.  When custom-fitted orthotics are included, treatments can be more effective and responses will be more comprehensive and longer-lasting. 

Table 1.

References

1. Kuhn DR, Shibley NJ, Austin WM, Yochum TR. Radiographic evaluation of weight bearing orthotics and their effect on flexible pes planus. J Manip Physiol Ther 1999; 22(4):221-226.

2. Stude DE, Brink DK. Effects of nine holes of simulated golf and orthotic intervention on balance and proprioception in experienced golfers. J Manip Physiol Ther 1997; 20:590-601.

3. Stude D, Gullickson J. Effects of orthotic intervention and nine holes of simulated golf on gait in experienced golfers. J Manip Physiol Ther 2001; 24(4):279-287.

4. Stude D, Gullickson J. Effects of orthotic intervention and nine holes of simulated golf on club-head velocity in experienced golfers. J Manip Physiol Ther 2000; 23(3):168-174.

5. Gatterman MI, ed. Chiropractic Management of Spine-Related Disorders. Baltimore: Williams & Wilkins, 1990:413.

6. Slosberg M. Effects of altered afferent articular input on sensation, proprioception, muscle tone and sympathetic reflex responses. J Manip Physiol Ther 1988; 11:400-408.

7. Wyke BD. The neurology of joints. Ann R Coll Surg Engl 1967; 41:25.

8. Freeman MAR, Wyke BD. Articular contributions to limb muscle reflexes. J Physiol 1964; 171:20.

9. Panzer DM, Fechtel SG, Gatterman MI. Postural complex. In: Gatterman MI, ed. Chiropractic Management of Spine-Related Disorders. Baltimore: Williams & Wilkins, 1990:263.

10. Bosien WR, Staples OS, Russell SW. Residual disability following acute ankle sprains. J Bone Joint Surg Am 1955; 37:1237.

11. Freeman MAR, Dean MRE, Hanham IWF. The etiology and prevention of functional instability of the foot. J Bone Joint Surg Br 1965; 47:678-685.

Children and Rehabilitation

by Kim D. Christensen, D.C., C.C.S.P., D.A.C.R.B.

Children, like adults, often need to do some exercises as part of their chiropractic treatment.  But how safe is exercise for children, especially exercise with resistance?  How much weight is appropriate for a growing body?  And which exercises are most effective?  Because of these and similar questions doctors of chiropractic may hesitate to recommend exercises for their younger patients.  Let’s see if we can arrive at a reasoned response, based on experience and useful consensus information.

Passing Phases

Prepubescence is the phase of childhood prior to the onset of secondary sex characteristics.  Rapid, but variable growth occurs during this period, with open physes and changing muscle and ligament lengths.  Adolescence begins with the onset of secondary sex characteristics and continues until physical and skeletal maturity.  Selecting the best exercise approach for each child’s situation is important, since needs may vary during growth. 1  However, all children should be encouraged to engage in frequent and regular fitness activities.

Exercise Benefits

The benefits of physical activity in youth include fitness, weight control, and the development of habits having the potential to span a lifetime.  One study systematically determined the amount of moderate-to-vigorous physical activity students obtain during elementary and middle-school physical education classes (time spent performing moderate-to-vigorous physical activity compared to total class time).  The researchers concluded that the amount of physical activity observed (elementary schools, 8.6%; middle schools, 16.1%) was significantly less than the estimated national average of 27%, and far below the national recommendation of a minimum of 50%. 2 

A review of current youth fitness data indicates that children in the United States are fatter, slower, and weaker than children in other developed nations.  Also, children in the United States appear to be developing a sedentary lifestyle at earlier ages.  A low level of exercise is a contributing factor for childhood obesity and hypertension, and predisposes the individual to premature death from coronary heart disease. 3  Fortunately, through intervention in children and adolescents in the form of education and motivation, exercise levels may be increased to the recommended minimum of 30 minutes on most days. 4

Safety Issues

High-intensity resistance training appears to be effective in increasing strength in preadolescents.  Children make similar relative, but smaller absolute strength gains when compared with adolescents and young adults.  Resistance training appears to have little if any hypertrophic effect, rather being associated with increased levels of neuromuscular activation.  Researchers have found that the risk of injury from prudently prescribed and closely supervised resistance training appears to be low during preadolescence. 5  In 1993, Mazur et al. reviewed the types and causes of injuries to preadolescents and adolescents resulting from weight lifting/training.  The researchers concluded that “prepubescent and older athletes who are well-trained and supervised appear to have low injury rates in strength training programs.” 6

A risk that must be considered in the immature skeleton is the susceptibility of the growth cartilage of the epiphyseal plates (physes).  Weight training in a submaximal controlled, supervised situation is beneficial to bone deposition.  Strength training can be a valuable and safe mode of exercise provided 1) instructors are properly educated; 2) participants are properly instructed; and 3) the absolute necessity of avoiding maximal lifts is reinforced. 7 

The most important factors in avoiding injury in children who are doing resistance exercises are: proper performance of the exercise; avoiding overload by focusing on repetitions, not weight; enforcing rest periods during exercise; and resistance training only twice a week.  Exercise tubing is an excellent tool for strength training of children, since the risks of injury are minimized, and a spotter or expensive equipment is not needed.

Training Balance and Coordination

For many children, it is more important to learn the fine neurological control necessary for accurate spinal and full body performance than to simply build strength.  Better balance and coordination will often result in improved physical function, both in daily and in sports activities.  This may entail performing exercises while standing on one leg, with the eyes closed, while standing on a mini-tramp, or using a rocker board.  The advantage of these balance exercises is seen when children engage in sports activities and perform at advanced levels for their age group.

All exercises are most effective when done in an upright, weight-bearing position, since the entire body is in a closed chain position during the training.  The stabilizing muscles, the co-contractors, and the antagonist muscles all learn to coordinate with the major movers during movements that are performed during closed chain exercising.  This makes these types of exercises very valuable in the long run, particularly for children who are interested in becoming competitive athletes.

Corrective Postural Exercises

Children’s spinal problems are often associated with poor postural support.  A spinal asymmetry such as scoliosis and kyphosis is invariably accompanied by neuromuscular imbalance.  This may be compounded by poor postural habits and tendencies to “slump.”  One important factor in chiropractic treatment is the correction of any loss of the normal upright alignment of the pelvis and spine.  In addition to general strengthening and coordination exercises, patients (including children) should be shown corrective exercises that are specific for the postural imbalances they have developed.  For instance, when the pelvis is carried flexed forward, a patient of any age will need to retrain with resisted pelvic extension exercises.  Likewise, when there is a forward head, posterior translation exercises for the cervical region are very important.

Whenever a child shows evidence of abnormal gait or begins to develop lower extremity complaints, a careful evaluation for the need for shoe inserts is warranted.  Custom-fitted orthotics can improve performance and spinal alignment by ensuring proper lower extremity alignment and reduce overuse injuries by providing additional shock absorption.

Conclusion

A well-designed exercise program for children who need to strengthen, develop better coordination, and improve postural support will allow the doctor of chiropractic to provide cost-efficient pediatric spinal care.  Exercises performed with the spine upright and functional can specifically train and condition all the involved structures to work together smoothly.  In some children, orthotic support is necessary to help ensure correct alignment from the lower extremities.  The end result is a more effective rehab component and young patients who will make a rapid response to their chiropractic care.  With a few common sense cautions and careful supervision, children are capable of performing rehabilitative exercises very safely.

References

1. American College of Sports Medicine. Guidelines for Exercise Testing and Prescription, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2000.

2. Simons-Morton BG, Taylor WC, et al. Observed levels of elementary and middle school children’s physical activity during physical education classes.  Prevent Med 1994; 23:437-441.

3. Cunnane SC. Childhood origins of lifestyle-related risk factors for coronary heart disease in adulthood.  Nutr Health 1993; 9:107-115.

4. US Dept. of Health and Human Services. Physical Activity and Health: a Report of the Surgeon General. Atlanta:1996. 

5. Blimke CJ. Resistance training during preadolescence: issues and controversies. Sports Med 1993; 15:389-407.

6. Mazur LJ, Etman RJ, Risser WL. Weight-training injuries: common injuries and preventative methods. Sports Med 1993; 16:57-63.

7. Schafer J. Prepubescent and adolescent weight training: is it safe?  Is it beneficial? Natl Strength Conditioning Assoc J 1991; 13:39-45.

About the Author

Kim D. Christensen, DC, DACRB, CSCS, CCSP founded the SportsMedicine & Rehab Clinics of Washington.  He is a popular speaker, and participates as a team physician and consultant to high school and university athletic programs.  He is currently a postgraduate faculty member of numerous chiropractic colleges and is the president of the American Chiropractic Association (ACA) Rehab Council.  Dr. Christensen is the author of numerous publications and texts on musculoskeletal rehabilitation and nutrition.  He can be reached at Chiropractic Rehabilitation Consulting, 18604 NW 64th Avenue, Ridgefield, WA 98642 or by email at kimdchristensen@hotmail.com.

Coordination of Gait

by Kim D. Christensen, DC, DACRB, CCSP

Bipedal human walking has an element of inherent unsteadiness.  Because of this, we require a substantial amount of coordination and balance control.  Our neurological system has a complex, but generally effective system for maintaining the dynamic equilibrium needed for smooth walking and even for more difficult gait activities, such as running and dancing.  However, problems in several anatomical regions can hamper this delicate mechanism, resulting in less economical -- and sometimes even pathological -- gait asymmetries.

The instability found in normal human walking results primarily from biomechanical disadvantages.  These include a heavily weighted upper body and a small base of support.  Perhaps most important, however, is the relatively long time we spend in single-support.  For about 80% of the gait cycle, we have all of our weight balanced over one leg.  A series of carefully coordinated muscle contractions is required to overcome this inherent unsteadiness by controlling the trunk and upper body. (1)  In other words, we incorporate compensatory muscle forces and joint torques onto the normal gait pattern to minimize the destabilizing forces which occur at certain points in the gait cycle.  These coordinated contractions help us to maintain balance during complex movements.  Unfortunately, this critical balance can be interfered with in several anatomical regions.

Dynamic Equilibrium

Efficient human gait is very dependent on a concept known as “dynamic equilibrium.”  This describes the balance that is required during the movements and instabilities which occur with bipedal locomotion.  As we move about from one location to another, maintaining dynamic equilibrium during walking ensures a steady and safe progression.  Two neurological control strategies are used to achieve this state in human walking: proactive balance and reactive balance. (2)

Proactive balance control arises primarily from the trunk and hip muscles.  These muscles contract in a sequence that activates postural adjustments to compensate for the destabilizing forces associated with walking movements.  Reactive balance control, on the other hand, is a strategy to recover from external disturbances that are encountered.  This has been found to occur primarily in the more distal muscles of the lower extremities. (3)  These two systems normally work together to counteract the various forces that are placed on our bodies during walking.  Problems arise when either the proximal or the distal balance control systems do not function smoothly. 

Lower Extremity Control

The distal balance control of the lower extremity must react rapidly to changes in terrain and ground reaction forces.  The mechanoreceptors in the feet and legs provide the information necessary for smooth and balanced coordination of the muscles in the lower legs.  From heel strike, through foot flat, to toe off, this region adapts to regain balance from moment to moment.

Problems that will interfere with this coordinated response to gait often arise in the complex biomechanics of the foot and ankle.  With many small joints, lots of connective and articular tissues, and both intrinsic and extrinsic muscles, the feet are very well supplied with proprioceptive nerve endings.  Mechanoreceptors in the joints, along with the muscle spindles of the foot muscles, are responsible for the positive support reflexes and a variety of automatic reflexive reactions. (4)  These include the flexor/extensor reflex, which converts the lower limb into a firm, yet compliant pillar.  Weightbearing compresses the joints and muscles, evoking reflexive activity in the extensors and inhibition of the flexor muscles. (5)  Particularly when there is excessive pronation, these reflexive responses are sluggish, and the reactive control of gait is poor.

Hip and Trunk Control

The proactive balance strategy for coordination of gait is found primarily in the trunk and hip extensor muscles, the erector spinae, hamstrings, and gluteus maximus, which start to become active before heel strike and stay active during the first half or the stance phase of locomotion. (6)  These proximal and trunk muscles must work together to maintain upper body steadiness and trunk rotation.  Recent studies have found that both aging (7) and low back pain (8) will interfere with normal functioning of this system.  In fact, both chronic and acute low back pain result in significantly altered muscle responses during gait. (9)

At the same time that gravity and ground reaction forces are affecting the legs and feet, the muscles of the trunk and even the shoulder must begin responding.  With each step, the scapula reacts to opposite-leg loading by tipping anteriorly in the sagittal plane, rotating upward in the frontal plane, and gliding around the ribcage in the transverse plane (protraction).  This reaction at the shoulder produces the appearance of a hunched and forward-rounded shoulder, and has been described as “shoulder pronation.” (10)  Appreciating the biomechanical and neurological processes that link shoulder pronation to lower extremity pronation on the opposite side helps us understand the complexity of gait coordination.

The Importance of Posture

In fact, as the leg is loaded in gait, trunk side-bending occurs to the loading leg.  The lumbar spine rotates away from the loaded leg, and a balancing rotation occurs in the thoracic spine to the same side as the loading leg.  The entire relationship of the shoulder, ribcage, and thoracic spine is driven by the cross-crawl neurological reaction to gait.  And even the upper cervical region plays an important role in maintaining and correcting postural alignment, and in determining whole-body balance.  The deep neck muscles have been found to have many more proprioceptive nerve endings than other skeletal muscles. (11)  The mechanoreceptors in the upper cervical joints are very sensitive to changes in postural alignment, and are a critical component (along with the vestibular system) in equilibrium and balance. (12)  In fact, deJong et al. were able to cause major changes in gait simply by anesthetizing the muscle and joint receptors in the neck. (13)

Conclusion

Coordination of gait is dependent on proper function in the lower extremity, as well as multiple factors in the proximal muscles and trunk.  The inherent instability of human walking requires a complex interaction to provide both proactive and reactive balance control.  Whenever the foot/ankle complex is not functioning correctly during the stance phase of gait, this stress is transmitted to the pelvis and spine with each step.  We can improve gait coordination and help to ensure balanced function throughout the entire musculoskeletal system with custom orthotic support for each phase of the gait cycle.  Such orthotics should be carefully designed to support the foot through all three parts of the stance phase – from heel strike, through foot flat, to toe off.

References

1. Winter DA, Ruder GK, MacKinnon CD. Control of balance of upper body during gait. In: Winters JM, Woo S-LY., eds. Multiple Muscle Systems: Biomechanical and Movement Organization. Berlin: Springer; 1990:534-541.

2. Patla AE. A framework for understanding mobility problems in the elderly. In: Craik RL, Oatis CA., eds. Gait Analysis: Theory and Application. St. Louis, MO: Mosby-Year Book; 1995:436-449.

3. Tang P-F, Woolacott MH, Chong RKY. Control of reactive balance adjustments in perturbed human walking: roles of proximal and distal postural muscle activity. Exp Brain Res 1998; 119:141-152.

4. Freeman MAR, Wyke BD. Articular contributions to limb muscle reflexes. J Physiol 1964; 171:20.

5. Panzer DM, Fechtel SG, Gatterman MI. Postural complex. In: Gatterman MI, ed. Chiropractic Management of Spine-related Disorders. Baltimore, MD: Williams & Wilkins; 1990:263.

6. Shiavi R. Electromyographic patterns in adult locomotion: a comprehensive review. J Rehabil Res Dev 1985; 22:85-89.

7. McGibbon CA, Krebs DE. Age-related changes in lower trunk coordination and energy transfer during gait. J Neurophysiol 2001; 85:1923-1931.

8. Selles RW, Wagenaar RC, Smit TH, Wuisman PIJM. Disorders in trunk rotation during walking in patients with low back pain: a dynamical systems approach. Clin Biomech 2001; 16:171-181.

9. Arendt-Nielsen L, Graven-Nielsen T, Svarrer H, Svensson P. The influence of low back pain on muscle activity and coordination during gait: a clinical and experimental study. Pain 1996; 64:231-240.

10. Walendzak D. Lower extremity theory enhances shoulder rehabilitation. Biomechanics 1998; 5(10):45-51.

11. Abrahams VC. The physiology of neck muscles; their role in head movement and maintenance of posture. Can J Physiol Pharmacol 1977; 55:332.

12. Wyke BD. Neurology of the cervical spinal joints. Physiotherapy 1979; 65:72-76.

13. deJong PT, deJong VB, Jonkees L. Ataxia and nystagmus induced by the injection of local anesthetics in the neck. Ann Neurol 1977; 1:240-246.

Hyperpronation: Treating Secondary Conditions

by Kim D. Christensen, DC, DACRB, CCSP

Patients seldom present with the complaint of “hyperpronation” or “excessive pronation.”  It is usually left to the doctor to realize that the reported problem is due to pronation.  Unfortunately, too many times the patient undergoes unnecessary or excessive examinations and treatment procedures, when the underlying problem is actually a hyperpronated foot (or feet).

What follows is a listing of commonly seen patient complaints that are frequently caused by (secondary to) excessive pronation, and which indicate the need for custom-fitted foot orthotics.  Patients with an obvious need should be fitted with orthotics early in their chiropractic care.  This will produce a good response to spinal and extremity adjustments, and will prevent frustration in both doctor and patient.

In the History

Back problems are worse with standing, walking, running.  When a patient reports a history of upright locomotor activities and spinal symptoms, a close evaluation of the feet will often identify excessive and/or asymmetrical pronation.  A brief gait evaluation should look for abnormalities such as foot flare or poor toe-off.  This clearly calls for orthotics to minimize the stress being transmitted from the lower extremities to the spine.

Recurrent ankle sprains.  A history of previous sprain injuries to one or both ankles indicates biomechanical instability and probable permanent ligament damage.  The important ligaments that support the arches of the foot are often injured during an ankle sprain, and arch collapse and/or unilateral hyperpronation can result.  Orthotics will provide the proprioceptive stimulus and mechanical advantage needed to prevent re-injury.

Family history of foot problems or surgery.  Since we inherit many health tendencies, a patient who has family members with foot problems and/or surgery has a much higher probability of the same.  Excessive calcaneal mobility, hallux valgus, plantar fascitis, and poor arch development are all associated with hyperpronation and appear to have a familial tendency.  Fitting for orthotics may prevent these problems from developing, and could avoid surgery.

Strenuous athletic activities.  Those who regularly engage in weight-bearing sports need both shock absorption and foot/ankle stability.  Patients who present with athletic injuries associated with their sport activities often demonstrate excessive pronation as a complicating and inhibiting factor. (1)  Orthotic support can increase performance and prevent injuries in a long list of individual and team sports -- such as running, tennis, skiing, skating, soccer, baseball, football, and basketball.

History of lower extremity stress fractures, tendinitis, shin splints, hamstring strains.  Whenever an athlete, whether recreational or competitive, reports symptoms of overuse injury (microtrauma) in the lower extremities, excessive pronation must be considered.  These conditions have been closely correlated with biomechanical asymmetries (such as hyperpronation) and require better support and shock absorption. (2)

Chronic knee pain, patellofemoral arthralgia, ACL injury.  The knee joint is a sensitive indicator of abnormal biomechanical stress, and many knee problems have been found to indicate the need for orthotics.  Controlling pronation decreases the rotational forces, which improves patellar tracking and protects the anterior cruciate ligament. (3)

During the Exam

Postural imbalances (pelvic tilt, scoliosis, forward head).  When a standing structural evaluation discloses a pelvic tilt (whether forward, backward, or low on one side), a lower extremity asymmetry due to unilateral or bilateral hyperpronation is likely.  Both functional and idiopathic types of spinal curvatures can be associated with pronation, and will benefit from the foot stabilization and neurological stimulus provided by orthotics.  Many postural complexes (forward head is one of the most common) are secondary to excessive pronation, with poor standing balance and proprioception from the feet.

Gait asymmetry, calcaneal eversion, foot flare.  Watching a patient walk, and looking for indicators of biomechanical asymmetry, will often demonstrate the need for orthotics.  Whenever there is excessive pronation, the foot and ankle complex does not function correctly during the stance phase of gait, and this stress is transmitted to the pelvis and spine with every step.

Foot calluses, bunions, hallux valgus.  A careful examination of foot problems will often show evidence of hyperpronation and arch collapse.  Heavy callusing, bunion development, and abnormal alignment all indicate the need for improved biomechanics and orthotics. (4)

Lack of an arch (especially unilateral).  This is easily seen during the weight-bearing portion of the exam, when a foot collapses under the weight of the body.  An even better method is the Navicular Drop Test, which measures the change in height of the medial longitudinal arch at the navicular prominence from sitting to standing. (5)  A foot without an arch will pronate excessively, and needs orthotic support. (6)

Knee instability, high Q-angle, poor patellar tracking.  When the knee does not align properly or track correctly, degenerative wear-and-tear and chronic symptoms will follow.  Orthotic alignment is required to reduce the abnormal pronation forces on this complex joint, which must be able to sustain frequent high forces during walking and running. (7)

On the X-rays

Scoliosis (functional or idiopathic), widespread disc degeneration.  The spine responds to poor support from one of the lower extremities by developing a lateral curvature.  Some studies indicate that gait disturbances (during the stance phase, in particular) may be one of the causative factors for idiopathic scoliosis. (8)  Significant intervertebral disc degeneration is made worse when the foot pronates, and transmits heel strike shock upwards into the spine.  In this case, orthotics with viscoelastic properties will often reduce chronic symptoms dramatically.

Unlevel sacral base, sacroiliac joint degeneration.  The pelvis shows evidence of inadequate support by the appearance of a tilted sacral base when standing.  This is often due to a functional short leg secondary to hyperpronation, which requires orthotic support. (9)  Sacroiliac degeneration may be due to chronic SI joint dysfunction, which may  be secondary to hyperpronation.

Low femur head, coxafemoral DJD.  These conditions are due to either an anatomical or a functional short leg, which are often associated with asymmetrical and/or excessive pronation.  Degenerative changes in the hip joint have been correlated with the stress of a longer leg.  Both will benefit from the improved balance and support provided by orthotics.

Heel spurs, DJD in knees, metatarsals.  X-rays of the feet and knees may reveal evidence of long-standing regional stress, such as degenerative changes in weight-bearing joints, and connective tissue calcification.  Calcium deposited in the calcaneal attachment of the plantar fascia specifically indicates the need for support of the arches of the foot.

Response to Care

Recurrent subluxations, symptom flare-ups.  Making the same adjustment to a patient’s spine again and again suggests poor structural support for the region.  Excessive pronation is often the underlying lack of proper support.  Orthotics have been used for decades by chiropractors who don’t want to continue adjusting the same area, and want to see the adjustment “hold” better.

Conclusion

Chiropractic care is based on the concept of the treating the cause, and not just decreasing the symptoms.  Our goal is to achieve long-term health, and not just short-term relief of pain.  As can be seen by the above list, excessive foot pronation can be the source of many of our patients presenting symptoms.  In fact, the feet are seldom painful in most of the conditions that are clear indicators of the need for orthotics.  All doctors of chiropractic must be alert for signs of lower extremity involvement in spinal conditions and musculoskeletal problems.

References

1. Freychat P et al. Relationship between rearfoot and forefoot orientation and ground reaction forces during running. Med Sci Sports Exerc 1996; 28:225-232.

2. Busseuil C et al. Rearfoot-forefoot orientation and traumatic risk for runners. Foot & Ankle Intl 1998; 19:32-37.

3. Beckett ME et al. Incidence of hyperpronation in the ACL injured knee: a clinical perspective. J Athl Train 1992; 27:58-62.

4. Eustace S et al. Hallux valgus, first metatarsal pronation and collapse of the medial longitudinal arch -- a radiological correlation. Skeletal Radiol 1994; 23:191-194.

5. McPoil TG, Cornwall MW. The relationship between static lower extremity measurements and rearfoot motion during walking. J Orthop Sports Phys Ther 1996; 24:309-314.

6. Dahle LK et al. Visual assessment of foot type and relationship of foot type to lower extremity injury. J Orthop Sports Phys Ther 1991; 14:70-74.

7. Eng JJ, Pierrynowski MR. Evaluation of soft foot orthotics in the treatment of patellofemoral pain syndrome. Phys Ther 1993; 73:62-70.

8. Giakas G et al. Comparison of gait patterns between healthy and scoliotic patients using time and frequency domain analysis of ground reaction forces. Spine 1996; 19:2235-2242.

9. Rothbart BA, Estabrook L. Excessive pronation: a major biomechanical determinant in the development of chondromalacia and pelvic lists. J Manip Physiol Therap 1988; 11:373-379.

Subluxations: What Role Do the Feet Play?

by Kim D. Christensen, DC, DACRB, CCSP

The importance of the feet to the normal functioning of the spine is often overlooked.  Because the feet are seldom symptomatic, busy chiropractors frequently forget to examine and adjust them.  Then finally, when a patient doesn’t respond as well as expected to chiropractic care, a source of interference is located in the pedal foundation.  A recent study concluded that “there are small, but important, inter-segmental movements of the spine during gait.” (1)  An abnormal gait, no matter what the source, will eventually interfere with these important movements, and subluxations may then develop.  But why is that?

The Foot / Spine Connection

When we stand, walk, dance, jump, and run, the feet are the foundation for the spine.  This foundation must bear the weight of the entire body (and considerably more during running and other sports).  If there is insufficient or inadequate support from the pedal foundation, the spine will be exposed to abnormal stresses and strains that eventually cause subluxations and back pain.  Recognizing and then responding appropriately to these factors allows doctors of chiropractic to effectively care for spinal subluxations.

Abnormal stresses on the pelvis and spine can be the result of excessive shock transmission, too much rotation, abnormal foot proprioception, or a functional short leg.  The cause of all four of these problems is often located in the feet.  When some part of the foot is not moving properly (either insufficient or excessive joint motion) the resulting forces produce effects all along the kinetic chain.  In fact, investigators have found that “Alteration of normal foot mechanics can adversely influence the normal functions of the ankle, knee, hip, and even the back.” (2)

Shock transmission.  Whether a foot tends toward hyperpronation or excessive supination, excessive shock is transmitted into the spinal joints.  “A high-arched (cavus) foot with limited range of motion attenuates shock poorly and a hypermobile flat foot also does poorly on shock attenuation because of its function near the end of the range of motion.” (3)  In either case, the forces are felt in the joints of the pelvis and spine.  In fact, absorbing the shock from the lower extremities may be one of the most significant long-term improvements that will be reported by patients with degenerative discs and spinal joints. 

Light and his colleagues studied the “brief but sizeable deceleration transient, which travels up the human skeleton on heel strike during normal walking”. (4)  In their classic investigation they found a significant stress that could be reduced by the use of viscoelastic heel pads.  Regarding the spine, they warned that “while the transients will load the majority of joints primarily in compression, shear stress will predominate in others, such as the spinal facet and sacroiliac joints.” (4)  This may explain the rapid response of lumbosacral and sacroiliac subluxations to the use of orthotics that contain shock-absorbing viscoelastic materials.

Rotatory stress.  When the foot and ankle stay too long in pronation, the entire lower extremity undergoes excessive medial (internal) rotation.  This causes a range of effects in the pelvis, sacroiliac joints, and spine. One doctor of chiropractic has described the numerous consequences as follows: “Based on excessive internal femoral rotation due to hyperpronation, there may develop compensatory shortening of the iliopsoas, which would draw the spinal column downward, forward, and rotate it contralaterally.  Unilateral iliopsoas involvement would cause a unilateral anterior pelvic tilt, while bilateral hyperpronation may result in an increased lordosis.” (5)  All of these changes can trigger the development of subluxations.

Altered proprioception.  Proprioceptors are the sensory organs that provide information regarding the status and function of the musculoskeletal system.  With many small joints, lots of connective and articular tissues, and both intrinsic and extrinsic muscles, the feet are very well supplied with proprioceptive nerve endings.  When there is a biomechanical dysfunction, it is likely that inaccurate neurological information is sent to the spinal cord, cerebellum, and brain from the feet.  This can have a detrimental effect on coordination and balance throughout the spine and pelvis. (6)  If inappropriate information is supplied by the position receptors, poor coordination of movement and gait can result in recurrent subluxations.

Dropped pelvis.  When there is a discrepancy in the length of the legs (whether anatomical or functional), the pelvis is lower on one side.  This asymmetry will cause vertebral rotation and recurrent subluxation (and possibly a functional scoliosis).  The most common cause of a functional short leg is a lowered medial arch and excessive pronation.  The study by Rothbart and Estabrook found a correlation factor of 0.97 between asymmetrical pronation and a pelvic tilt to the same side. (7)  In these sorts of cases, there is difficulty in eliminating the pelvic and spinal subluxations without treating the feet.

What To Do

Every patient with subluxations should be checked for abnormal foot biomechanics.  This evaluation can be quick and easy, and is not painful to the patient.  The feet may need to be adjusted, so that numerous joints can move smoothly during each phase of gait.  And most patients with biomechanical foot problems will benefit from the long-term support provided by custom-fitted orthotics.

Evaluate.  There are five lower extremity “flags” to look for in every patient:

? Watch the patient walk -- look for foot flare (toe-out) or toe-in.

? Look at the shoes -- check for excessive lateral heel wear

? Check the kneecap alignment -- medial facing (“squinting”) patellae.

? Look at the Achilles tendons -- medial bowing is associated with an everted

   calcaneus.

? Palpate the medial arches -- check for lack of an arch and/or painful plantar

   fascia.

Since excessive collapse of the medial arch is a very important component of most foot problems, the navicular drop test is a useful tool.  This procedure is objective, quick, and helps in the documentation to patients and insurance companies.  The position of the navicular prominence is noted when non-weightbearing, and then compared to its position when bearing the weight of the body.  A large difference between the two positions indicates excessive collapse of the medial arch of the foot.  Any significant asymmetry provides evidence of loss of symmetrical gait.

Adjust.  When the foot is not functioning smoothly, and especially when there is excessive pronation (the most common biomechanical foot problem), specific adjustments are needed.  Table 1 lists the usual foot subluxations seen with excessive pronation.  I use standard adjusting methods to adjust whichever areas are found to be misaligned.

Orthotics.  When the feet have biomechanical problems, adjustments can be helpful, but orthotics are often necessary for long term support.  A properly designed and custom-fitted orthotic will provide the following corrections throughout the day and during all locomotor activities:

? Shock absorption from viscoelastic materials ease the impact at heel strike and

   reduce the forces on degenerated joints.

? Decreasing the extent and speed of pronation reduces the medial rotation force that is transmitted up the leg into the pelvis and spine.

? Improved alignment and mobility of the arches, with less muscle and

   connective tissue stretch, provides more accurate proprioception for better

   balance and alignment.

? Reducing calcaneal eversion with a “pronation wedge” and supporting the

   medial arch limits the dropping of the pelvis during gait.

Conclusion

When a patient presents with subluxations, especially ones that do not correct rapidly and completely, a search for contributing factors must include examination of the feet.  The best way is to screen all new and returning patients for the five lower extremity  “flags.”  Performing the navicular drop test will provide the necessary documentation for the need for orthotics.  Custom-fitted orthotics are needed in most cases for long-term spinal stabilization.  Flexible orthotics made from viscoelastic materials are a very useful approach for most patients with recurrent spinal subluxations.  Even expertly applied spinal corrections will often be only partially successful until the lower extremity problems are uncovered, corrected, and supported for the long haul.

References

1. Sychewska M, Oberg T, Karlsson D. Segmental movements of the spine during treadmill walking with normal speed. Clin Biomech 1999; 14:384-388.

2. Katoh Y et al. Biomechanical analysis of foot function during gait and clinical applications. Clin Orthop Rel Res 1983; 177:23-33.

3. Subotnick SI. Forces acting on the lower extremity. In: Sports Medicine of the Lower Extremity. New York: Churchill Livingstone, 1989:189.

4. Light LH, McLellan GE, Klenerman L. Skeletal transients on heel strike in normal walking with different footwear. J Biomech 1980; 13:477-480.

5. Hammer WI. Hyperpronation: causes and effects. Chirop Sports Med 1992; 6:97-101.

6. Fitz-Ritson D. The anatomy and physiology of the muscle spindle and its role in posture and movement: a review. J Can Chiro Assoc 1982; 26:144-150.

7. Rothbart BA, Estabrook L. Excessive pronation: a major biomechanical determinant in the development of chondromalacia and pelvic lists. J Manip Physiol Therap 1988; 11:373-379.

8. Charrette MN. How I adjust the excessively pronated foot. Success Express 2000; 20(3):31-34.

[Table 1]

*Most common direction of subluxation in adults

Table I. Excessive Pronation Subluxation Pattern (8)