Foot Pain Causes, Other Symptoms, Diagnosis and Treatment on MedicineNet.com

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Foot Pain

Author: Jayson Goo, ATC, MA, CKTI
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

How is the foot designed?

The foot is an intricate structure of 24 bones that form two arches. The longitudinal arch runs the length of the foot, and the transverse arch runs the width. The ankle joint is the interaction of the foot and the lower leg, and the toes are on the far side of the foot. The bones of the foot are primarily held together by the shape that they fit with each other and by a fibrous tissue known as ligaments. The muscles of the foot, along with a tough, sinewy tissue known as the plantar fascia, provide secondary support to the foot. The foot has internal muscles that originate and insert in the foot and external muscles that begin in the lower leg and attach in various places on the bones of the foot. There are also fat pads in the foot to help with weight-bearing and absorbing impact during weight-bearing.

Picture of the Anatomy of the Foot

Picture of the metatarsal (foot) and calcaneus (heel) bones, the plantar fascia ligament, and the Achilles tendon of the lower leg and foot

The foot is the foundation of most athletic movements. Pain indicates that there is something wrong with either the interaction of internal structures of the foot or with the how the foot is interacting with external influences. How and when the pain occurs and the locations of the pain are the primary clues to what may be causing the pain. When there is pain, the body reacts by changing the way it moves or functions in an effort to reduce the pain. Biomechanical changes or disease may prevent the normal movement and cause further injury.

What causes foot pain?

Foot pain may be caused by many different things. Trauma, disease, or a combination of both are the most common causes of foot pain. Trauma is a result of forces outside of the body either directly impacting the body or forcing the body into a position where a single or combination of forces result in damage to the structures of the body. Poor biomechanical alignment may lead to foot pain.

Injuries such as ligament sprains, muscle strains, bruises, and fractures typically occur suddenly (acutely). Sprains, strains, bruises, and fractures may be the result of a single or combination of stresses to the foot. A sprain of the foot or ankle occurs when ligaments that hold the bones together are overstretched and the fibers tear. The looseness or tightness of ligaments in the joints of the foot may be a factor in foot pain.

The muscle's bursa and fascia of the foot can be strained by overstretching, overuse, overloading, bruising, or being cut such as in stepping on a sharp object. Achilles tendonitis is a common muscle injury of the tendon that attaches at the back of the heel.

Injury to the bones and joints of the foot can be caused by a single blow or twist to the foot, or also by repetitive trauma that can result in a stress fracture. A blunt-force injury such as someone stepping on your foot may result not only in a bruise (contusion) injury but also damage to the primary and secondary structures (muscles and ligaments) of the foot. Direct blows to the foot can cause bruising, breaking of the skin, or even fracturing of bones. Metarsalgia is the irritation of the joints of the foot. An example of metarsalgia is "turf toe," a common athletic injury in which the tendon under the joint at the base of the big toe is strained. Trauma to the toenail can cause pooling of blood under the nail and the temporary or permanent loss of a toenail. Repetitive trauma to the bones, muscles, and ligaments can result in extra bone growth known as spurs or exostosis.

Injuries to both the skin covering and the internal structures may also be caused by multiple small repetitive traumas. Micro-trauma injuries can be caused by running on uneven surfaces, surfaces that are too hard or too soft, or shoes that have poor force-absorption qualities or fit incorrectly. Repeated overstressing of the same structure of the foot may cause stress fractures, tendonitis, plantar fasciitis, and acute and chronic osteoarthritis.

The arches are the primary structures of the body that absorb and return force to and from the body to the outside world when we are on our feet. Injury to the plantar fascia is a common cause of arch pain. The plantar fascia is a tough fibrous sheath that extends the length of the bottom of the foot and lends support to the arch. When the plantar fascia is damaged, the resulting inflammatory response may become a source of arch pain. High and low arches (flat feet) may cause the foot to function biomechanically in such a way as to cause pain.

Footwear can be a contributor to foot pain. Poor fitting shoes in the short term can cause blisters, calluses, bruising and be a source of athlete's foot. The long-term effects may be bunions, corns, irritation of nerves and joints, misalignment of the toes, and the source of microtrauma injuries to the foot.

Disease, viruses, fungi, and bacteria may also be the sources of foot pain. Diabetes, Hansen's disease, and gout are common diseases that affect the foot. Numbness and change in sensation known as peripheral neuropathy may be a result of these diseases. Plantar warts caused by a virus can become sources of irritation. Athlete's foot caused by a fungus has also been known to develop complications from both bacterial and viral source. A common self-inflicted cause of foot pain is the ingrown toenail. Ingrown toenails occur when the edges of the nail grow through or into the skin, resulting in irritation and sometimes leading to infection.