Hallux valgus
| Bunion | |
|---|---|
| Synonyms | Hallux abducto valgus |
 |
|
| Classification and external resources | |
| Specialty | Orthopedics |
| ICD-10 | M20.1 |
| ICD-9-CM | 727.1 |
| DiseasesDB | 5604 |
| MedlinePlus | 001231 |
| eMedicine | orthoped/467 |
| Patient UK | Bunion |
| MeSH | D006215 |
A bunion is a deformity of the joint connecting the big toe to the foot. It is characterized by medial deviation of the first metatarsal bone and lateral deviation of the hallux (big toe), often erroneously described as an enlargement of bone or tissue around the joint at the bottom of the big toe (known as the metatarsophalangeal joint).
There is disagreement among medical professionals about the cause of bunions. Some see them as primarily caused by the long-term use of shoes, particularly tight-fitting shoes with pointed toes. Others believe that the problem stems from genetic factors that are exacerbated by shoe use. Bunions occur when pressure is applied to the side of the big toe (hallux) forcing it inwards towards, and sometimes under or over, the other toes (angulation). As pressure is applied, the tissues surrounding the joint may become swollen and tender. In a survey of people from cultures that do not wear shoes, no cases of bunions were found, lending credence to the hypothesis that bunions are caused by ill-fitting shoes.
The bump itself is partly due to the swollen bursal sac or an osseous (bony) anomaly on the metatarsophalangeal joint. The larger part of the bump is a normal part of the head of the first metatarsal bone that has tilted sideways to stick out at its distal (far) end.
The symptoms of bunions include irritated skin around the bunion, pain when walking, joint redness and pain, and possible shift of the big toe toward the other toes. Blisters may form more easily around the site of the bunion as well.
Having bunions can also make it difficult to find shoes that fit properly and bunions may force a person to have to buy a larger size shoe to accommodate the width the bunion creates. When bunion deformity becomes severe enough, the foot can hurt in different places even without the constriction of shoes because it then becomes a mechanical function problem of the forefoot.
Bunions are sometimes genetic and consist of certain tendons, ligaments, and supportive structures of the first metatarsal that are positioned differently. This bio-mechanical anomaly may be caused by a variety of conditions intrinsic to the structure of the foot – such as flat feet, excessive flexibility of ligaments, abnormal bone structure, and certain neurological conditions. These factors are often considered genetic. Although some experts are convinced that poor-fitting footwear is the main cause of bunion formation, other sources concede that footwear only exacerbates the problem caused by the original genetic structure.
...
Wikipedia