Supination of the foot occurs normally during gait, causing the foot to move down and inward at the subtalar joint, which is part of the ankle joint. According to SportsInjuryClinic.net, during supination most of the body weight is placed on the outside of the foot as it gets ready to move forward. Over-supination, which can occur in conjunction with some structural abnormalities of the foot such as a cavus or high-arched foot, can cause foot problems.
Ankle Sprain
Those with a supinated foot type are more likely to suffer an ankle sprain due to lateral instability. An ankle sprain occurs when the ankle is forced out of its normal position due to instability while walking, tripping or falling. The ligaments, which connect bones together, on the outside of the ankle are injured due to over-stretching or tearing, according to Foot Health Facts. Ankle sprains cause pain, swelling, stiffness in the joint and possibly bruising at the site of the sprain. The pain and swelling from some ankle sprains can be so severe as to make walking difficult.
Shin Splints
Excess supination of the foot can lead to injuries that result from reduced shock absorption, according to The Stretching Institute. A foot which over-supinates does not absorb as much shock as it should during heel strike due to decreased amount of pronation. This can lead to over-use injuries, such a shin splints. Shin splints cause pain along the inner edge of the tibia, in the front of the leg. The muscles, tendons ligaments, periosteum that covers the bone and the bone itself are all affected, becoming inflamed and painful, especially while walking.
Stress Fractures
Those with a supinated foot type can also suffer from recurrent stress fractures due to the reduced amount of shock absorption. According to the American Academy of Orthopaedic Surgeons, a stress fracture occurs when the muscles are over-used and do not absorb shock properly, transferring the forces to the bone. The repetitive stress can cause a small crack or fracture in bones of the foot or ankle. The pain of a stress fracture appears suddenly and goes away with rest. Over time, the pain can become debilitating, requiring complete rest of the affected leg or foot including the use of crutches in order to get around.
Plantar Fasciitis
The decreased shock absorption of the supinated foot can also lead to developing plantar fasciitis. According to MedlinePlus, plantar fasciitis occurs due to swelling and inflammation of the plantar fascia, the thick ligamentous band of tissue that runs from the heel to the ball of the foot. Plantar fasciitis most often presents as pain in the heel of the foot, along with swelling and tenderness. The pain is typically worse in the morning, becoming better with movement throughout the course of the day. The pain usually feels better with rest.
