With 26 bones, 33 joints, and 112 ligaments, the human foot is an intricate skeletal structure. The foot, in concert with the entire musculoskeletal system, is the launching pad for dynamic athletic movements that routinely generate forces that when absorbed by the foot, exceed four times or more the weight of the athlete.
Different sports may demand repetitive foot movements, such as the strike of the foot on the ground or the track while running. Other athletic endeavors involve sudden, explosive footwork, such as in soccer or rugby. Each type of foot mechanics creates distinct prospects for foot injury. Foot injuries that occur to the bones or ligaments most often result from misalignment of the structure.
Foot injuries may be placed within three general classifications: skin, toenail, or blister injuries. These injuries are not structural in nature, but are caused by an external agent. The most common examples of such injuries include athlete's foot (tinea pedis), a fungal infection; ingrown toenail, in which the nail cuticle grows into the surrounding skin, causing infection; and blisters, which result from poorly fitting socks or shoes.
Injuries caused by either overuse or as a result of a structural misalignment are similar in that only through significant activity do preexisting or under-lying structural problems usually reveal themselves. The significant overuse sports injuries that occur in the foot include a sprained metatarsalphalangeal (MTP) joint, plantar fasciitis, misaligned bones or tendons in the foot, bunions, neuroma, calcaneal bumps, and stress fractures.
A sprained MTP (big toe) joint often presents as "turf toe" so-called due to injuries created through running on artificial surfaces. This type of sprain is caused by a sudden bending of the big toe joint in an upward direction. This movement results in damage to the ligament of the big toe, which connects it to the metatarsal bone.
Plantar fasciitis occurs when the tendon that extends beneath the sole of the foot from the heel to the toes becomes irritated, causing pain when the athlete places significant pressure on the foot through running or jumping. This condition is caused by the over-pronation (inward turning) of the foot as the foot strikes the ground while running. The condition is often corrected with the use of an orthotic, a device inserted into the athlete's shoe to correct misalignment.
The misalignment of the tendons of one or more toes cause a condition known as "hammer toe." Over-pronation causes the tendons to pull the toe structure out of its natural position, resulting in a bent toe and painful cramping of the foot inside a shoe. In its early stages, before the joint in question becomes immobile, a hammer toe can be corrected with an orthotic.
A bunion is a bony outgrowth that extends from the base of the big toe. This condition is also caused by either over-pronation or as a result of wearing overly tight shoes. Bunions place significant pressure on the foot and can impair athletic performance. A very large bunion is often surgically removed; lesser bunions can usually be addressed with an orthotic.
A neuroma is the constriction of a nerve in the forefoot between the third and fourth toe, usually caused by over-pronation; the motion of the foot as it pronates creates a measure of slackness in the metatarsal bones that then come into contact with the nerve. Depending on the extent of the damage to the nerve, the treatment for this condition will range
Metatarsalgia occurs when one of the five metatarsal bones is not aligned with the others; the misaligned bone will often cause pain in the forefoot during running, at the point where the metatarsal meets the toe. The condition may be corrected by a device as simple as a rubber pad inserted in the shoe at the point below the misaligned bone, so as to raise it to the same profile as the other metatarsals.
Calcaneal bumps, also referred to as heel spurs, are bony growths that develop on the back of the calcaneus, or heel bone. Often associated with the development of a plantar fasciitis condition, the pressure created by the calcaneal bump irritates the ten-don when the foot of the runner strikes the ground. The condition is primarily managed through the use of cushioned shoes and anti-inflammatories. In severe cases, the bone spur is surgically shaved away.
A stress fracture is a break in a bone of the foot that is most commonly caused by repetitive stress placed upon the structure, where the alignment of the bone to the rest of the skeleton of the foot is not symmetrical. Significant overtraining in running or high intensity training on a hard surface to which the athlete is not accustomed are common stress fracture mechanisms. A stress fracture will usually be revealed in an x-ray as a small crack, or fissure, on the bone surface. Foot stress fractures often occur in the second, third, or fourth metatarsals.
Given the relative size of the bones of the foot, a fracture resulting from a trauma is a regular, if not common, occurrence in sport. Such injuries include an object falling on the foot, such as might occur in a weight training accident, or an object forcefully colliding with the foot, such as a fast bowled cricket ball or a baseball. The calcaneus (heel bone) often is chipped when the Achilles tendon ruptures, pulling the base of the tendon away from the bone.