During initial contact or heel strike, the ankle rolls inward, causing excessive pronation or flattening of the foot. This action forces the big toe (instead of the ball of foot and all toes) to do all the work to push off the ground. When the ankle overpronates, this causes the tibia (shin bone) to rotate and the femur (thigh bone) to adduct (move toward the mid-line of the body), causing internal rotation or knee valgus (knock-kneed).
In adults, the most common reason for the onset of Over-Pronation is a condition known as Post Tibial Tendonitis. This condition develops from repetitive stress on the main supporting tendon (Posterior Tibial Tendon) of the foot arch. As the body ages, ligaments and muscles can weaken. When this occurs the job of providing the majority of the support required by the foot arch is placed upon this tendon. Unfortunately, this tendon cannot bear the weight of this burden for too long. Eventually it fatigues under the added strain and in doing so the foot arch becomes progressively lower over a period of time.
Because pronation is a twisting of the foot, all of the muscles and tendons which run from the leg and ankle into the foot will be twisted. In over-pronation, resulting laxity of the soft tissue structures of the foot and loosened joints cause the bones of the feet shift. When this occurs, the muscles which attach to these bones must also shift, or twist, in order to attach to these bones. The strongest and most important muscles that attach to our foot bones come from our lower leg. So, as these muscles course down the leg and across the ankle, they must twist to maintain their proper attachments in the foot. Injuries due to poor biomechanics and twisting of these muscles due to over-pronation include: shin splints, Achilles Tendonitis, generalized tendonitis, fatigue, muscle aches and pains, cramps, ankle sprains, and loss of muscular efficiency (reducing walking and running speed and endurance). Foot problems due to over-pronation include: bunions, heel spurs, plantar fasciitis, fallen and painful arches, hammer toes, and calluses.
Bunions, calluses and crooked toes may indicate alignment problems. So, it is important to ascertain the condition of a client’s toes. Check the big toe to determine if the first joint of the toe is swollen, has a callus or bunion, and/or looks as though it abducts (i.e., hallux valgus) rather than pointing straight ahead. Also, look to see if the lesser toes seem to “curl up” (i.e., the person has hammer or claw toes). This may be indicative of damage to, or inflexibility of the plantar fascia caused by excessive flattening of the foot.
Non Surgical Treatment
One of the best forms of treatment for over pronation is wearing supportive shoes. Shoes should have ample support and cushioning, particularly through the heel and arch of the foot. Without proper shoes, there may be additional strain on the tissue in the foot, greatly contributing to or causing an occurrence of over pronation. Rarely is surgery considered to relieve the pain and damage that may have resulted from this condition. Orthotic shoe inserts are often the easiest and most effective way to correct pronation.
Subtalar Arthroereisis. Primary benefit is that yje surgery is minimally invasive and fully reversible. the primary risk is a high chance of device displacement, generally not tolerated in adults.
An implant is pushed into the foot to block the excessive motion of the ankle bone. Generally only used in pediatric patients and in combination with other procedures, such as tendon lengthening. Reported removal rates vary from 38% – 100%, depending on manufacturer.