What is the role of orthotics?
The purpose of custom foot orthotics is to place the foot in a position of improved mechanical efficiency. This allows the joints and muscles to be more favourably positioned to withstand the repetitive forces applied to them. Foot orthotics are recognized as an important adjunct to treatment of the lower extremity dysfunction. The foot in motion can be generally classified as "normal", over pronated or over supinated.
Normally the foot pronates from heel strike to early midstance to adapt to the ground surface and absorb shock. Next, the foot normally supinates to be used as a stable rigid lever for push-off. It is very detrimental for the foot and higher in the kinetic chain if the foot stays pronated (unstable) through late midstance and push-off. Over pronation of the foot results in talus adduction, leading to excessive or ill-timed internal rotation of the tibia, functional genuvalgus and consequences throughout the kinetic chain. It is very important in this case to control excessive and potentially harmful subtalar and midtarsal joint movement. The purpose of the orthotic is to maintain a neutral position of the joints within the foot.
If the foot is over supinating, the joints are essentially "locked" or rigid, and a neutral position is unachievable. When the foot is constantly in a supinated position it is unable to absorb ground reaction forces and the forces transfer to the ankles, knees, hips and spine. Orthotics strategy in this case is to absorb some of the ground forces. Rather than building an orthotic to change the position of the joints within the feet, a flexible orthotic would be prescribed to absorb ground reaction.
Many conditions have a biomechanical cause and until the underlying cause is corrected the symptoms will not resolve entirely. Some common conditions which often benefit from biomechanical foot correction with orthotics include:
- Achilles Tendonitis
- Shin Splints
- Patellofemoral Syndrome
- Hallux Valgus associated with over pronation
- Mortons neuroma
- ITB Syndrome
And in some cases even low back pain.