by Mark Charrette, DC
Children's feet undergo marked developmental changes throughout the first six or seven years of life. Incidence of flat feet, knock knees, or other abnormality in a young patient does not always signal the need for therapeutic intervention, as is recommended for adult subjects. Yet these conditions, along with gait abnormalities, pigeon toes, and bow legs, are the more common signs that cause parents to seek biomechanical evaluation of their children.1
Young feet have not experienced the years of standing, walking, wearing shoes, or other stresses that exact a high price from the adult foot. Prolonged and repeated stress to pedal soft tissues can create deformation that interferes with structural mechanical interactions.2 This explains why an estimated four out of five people older than 20 experience some form of foot dysfunction.3
Architecture of the Foot
The mature foot displays a sound architectural structure that provides for balanced disbursement of body weight in response to gravity. Weight travels through the ankle, where about half the load is borne at the heel. The remainder is divided between anterior medial and lateral supports, which, with the heel, define a plantar vault.4
The developing foot of a child displays no distinct architecture for about the first 18 months of life. Soft tissue and adipose tissue are its main components. From 18 months until about age six, rapid development occurs in bony structures and the longitudinal arch.
Weight distribution patterns change as this pedal development progresses. The toddler sways in learning to walk because the foot has limited weight-bearing abilities. Higher loading values are recorded in the midfoot region, and metatarsal loading is roughly equal. As the musculoskeletal frame continues to grow, the pedal foundation seems to shape itself to provide better support. Loading of the midfoot decreases, and the third and fifth metatarsals begin to bear more weight.5
Normal Foot Function
The feet serve the body in three ways: bearing weight, assisting locomotion, and receiving the impact of gravitational force, also known as heel strike shock. In the adult foot, these functions occur in the stance phase of gait, which can be broken down into three major components6:
- Contact. As the heel touches the ground, a natural inroll of the subtalar joint begins. This is known as pronation. The tibia also rolls inward, and the knee flexes, causing response in the femur, pelvis, and spine. This kinetic sequence activates the body's natural shock absorbers to reduce forces that, left unchecked, could have pathological influences on the spine and other upper body structures.7
- Midstance. Body weight shifts from the heel to the forefoot, causing an outroll or supination in pedal structures. The tibia and femur also turn outward as the knee unflexes.
- Toeing off. This propulsion phase sees the foot acting as a rigid lever to shift, beginning the swing phase of stance, when the foot loses ground contact. Leg bones remain externally rotated until the next heel strike, when this three-part cycle is repeated.
The underdeveloped foot of a child accomplishes gait without displaying this kind of synchronized process. Before independent stance is possible, it is typical to observe bowed legs and feet that point inward. Uterine crowding and a normal fetal positioning with one leg crossed over the other are contributing factors.1
As the child begins to walk and the lower extremities bear weight, the bowing and toe positions normalize. Then skeletal growth begins to accelerate, and genu varum (or toeing in) may reappear for the next few years. By age six or seven, when growth rates begin to stabilize, a return to normal healthy alignment should be observed.
This is the stage when concern for the child's pedal integrity is appropriately pursued. A musculoskeletal examination can be conducted, because ossification of bony structures is usually complete, even if the epiphyses are not entirely closed.8
In children, the effects of pedal dysfunction may not be readily apparent, waiting until the subject is well into the adult years to manifest. Cases of low back, knee, and hip problems; postural fatigue; scoliotic deviations; and plantar fascitis in adults have all been linked to untreated childhood pedal imbalance.7,9
Hyperpronation again may be the culprit in these cases. It is one of the leading foot problems detected among children in the elementary school years, ages six through 12. Three separate studies conducted at 20-year intervals found the condition in 29%, 28%, and 35% of the test populations.10
The immediate effect of hyperpronation on young feet is an abnormal abduction during gait. Body weight shifts over the foot before stance-phase muscles are prepared to provide adequate support.11 The effect becomes even more pronounced in running, because body weight shifts more to the medial aspect of the feet.5
Examining Children's Feet
The same "five red flags" used to identify potential problems in adult feet can be applied to patients aged 6 or older.
- Toe position. As the child walks, look for signs of toeing out or inward. If possible, gait should be observed before the child is aware that an examination is under way, to obtain the most natural results. The parent might also be able to provide information on the child's normal walking patterns.
- Dropped arches. As the child stands barefoot, slide an index finger beneath the longitudinal arches. Abnormally low arches will not comfortably accommodate the finger past the first knuckle. Pain on palpation and tissue tightness that is relieved by shifting weight outward are other indicators of imbalance.
- Tendon bowing. Observation of the Achilles tendons will usually reveal bowing in the presence of hyperpronation. Measure the distance from the navicular to the floor when the child is in a normal resting stance. Next, manipulate the subtalar joint to a neutral position and repeat the measurement. The average limit for all ages is about three-eighths of one inch.1
- Patellar displacement. The normal inroll of pronation causes an inward movement of the patella. Excessive pronation might be accompanied by perpetuation of this patellar displacement. Comparative measurements of the distance between two marks on the knees, taken with the feet in normal stance and then manipulated to a subtalar neutral position as described above, can be revealing.
- Shoe condition. Foot imbalance will cause excessive wear on the lateral aspect of shoe heels. Check the condition of shoes for more clues to the health of a child's feet.
Use of a tread mat or similar surface that records foot patterns during gait is another useful diagnostic tool. Key indicators that can be observed include gait angles, step length, base of step, stance angle, and scuffing.1
Therapeutic Orthotic Support
The use of functional orthotics to enhance the supportive and biomechanical properties of the pedal foundation—and the kinetic interaction of upper-body structures—has been validated in numerous studies and clinical experience.6,12,13,14 Functional orthotics offer the developing foot a degree of control in motion that need not disrupt complex structural interrelationships.
The goal of orthotic therapy is to control, not restrict, motion. By enhancing support of the longitudinal arch, orthotics can reduce deformation of pedal tissues.13 This, in turn, encourages joint stability, which provides optimal support of the lower extremities and, ultimately, greater postural integrity of pelvic and spinal structures.
The role of the foot as shock absorber is also enhanced when pedal imbalance is alleviated with flexible orthotics. Young bones and immature joints are especially vulnerable to the effects of pathological heel strike shock. By normalizing subtalar pronation and accompanying internal leg motion, orthotics help the body's shock absorbers to function most effectively.6
The special concerns of young patients are addressed in a functional custom orthotic made of leather bottoms with shock-absorbent heel pads, topped by a moisture-resistant synthetic material to withstand active wear. Leather is preferred for its moderate rigidity while allowing lateral compression and expansion for optimal integration of orthotic, shoe, and foot.9
Orthotics for children must take into account the rapid growth rates of this patient group. The best results can be obtained when the shoe, foot, and orthotic function as an integrated unit. Therefore, refit children with new orthotics for every increase of one and a half sizes in shoes.12
About the Author
Dr. Mark N. Charrette is a 1980 summa cum laude graduate of Palmer College of Chiropractic. Over the past 15 years, he has lectured extensively on spinal and extremity adjusting throughout the United States, Europe, the Far East, and Australia. Dr. Charrette received a Bachelor’s degree from Illinois State University (summa cum laude) in 1976 where he was an NCAA All-American in 1974.
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