Pediatric Biomechanics

Pediatric Biomechanics

Kids are not simply little adults, especially when it comes to their physiology. To understand pediatric biomechanics as it relates to lower limb pain, there are specialized and unique principles at play. In this article we’ll explore a few common pathologies, and get those kids playing pain free!

A pronated foot is normal in the early years of development. Ambulators up to fourteen months of age may demonstrate a calcaneal stance position of up to 7 degrees of eversion. Normally this reduces to perpendicular by the age of seven.

It is difficult to determine if a child is predisposed to maintaining their pronated gait in later years. A history of excessive medial or lateral heel wear, wearing out the shoe before outgrowing it, and complaints of fatigue are generally indicative of abnormal function. Foot and leg soreness lasting longer than six months usually indicates more than just normal growing pains. When a child is having difficulty ambulating by the fourteenth month, there is usually some lower extremity pathology present.

Diagnosis and Treatment

Talipes Calcaneo Valgus

This deformity is represented by a dorsiflexed, everted and abducted foot relative to the leg. It is generally attributed to abnormal inverted compression. When this deformity is rigid and the foot cannot be passively maintained in an adducted and plantarflexed attitude, serial plaster immobilization followed by night splint therapy is the treatment of choice. It is essential that the diagnosis and treatment for this deformity be performed before the child initiates ambulation.

Rocker Bottom Flatfoot

This type of deformity can develop in a child with a lack of dorsiflexion at the ankle joint. Normally 75 degrees of dorsiflexion is present in the newborn, 15 degrees at age 10, and 10 degrees at age fifteen. If the equinus is fully compensated there will be excessive dorsiflexion at the oblique axis of the midtarsal joint. This causes the classic rocker bottom flatfoot. Orthotics and exercised are indicated. If this treatment fails, if the child exhibits 0 to 5 degrees of dorsiflexion, and if subluxation of the midtarsal joint is also present, then some type of Achilles tendon lengthening is indicated.

Internal Femoral or Tibial Torsion

This should be treated with functional orthotics. Although this condition may reduce by age fourteen, the secondary pronatory forces which influence the child’s foot during development must be controlled. Even though an effective functional orthotic will generally adduct the foot even further, the child’s foot will not continue to compensate for the adducted gait via oblique midstarsal joint subluxation.

Forefoot Varus

Functional orthotics are indicated if the child’s forefoot is inverted to the rearfoot,. However, this has to be differentiated from a forefoot supinatus which is a soft tissue deformity. A forefoot varus is a structural deformity. A forefoot supinatis in children is usually due to a compensated gastrocnemius equinus which causes the midtarsal joint to become supinated. An Achilles tendon lengthening may be required.

Forefoot Valgus

This can cause juvenile hallux valgus due to late midtarsal joint pronation in the flexible type forefoot valgus with a hypermobile first ray. Both the rigid and the flexible forefoot valgus deformities respond well to functional orthotics.

We recommend children’s orthotics be ordered with a deep heel cup for maximum control. If a child’s gait cannot be controlled through the use of appropriate shoe gear and neutral position functional orthotics, surgical interventions should be considered. There are a variety of orthotic devices available to help with the unique needs of the pediatric patient. Paragon also offers colourful cover materials so kids will be more inclined to wear their devices.