Bunion

Bunion
Synonyms Hallux abducto valgus
Specialty Orthopedics

A bunion is a common deformity of the joint connecting the big toe to the foot. It is characterized by the first metatarsal bone deviating toward the midline of the body and the big toe deviating away from the midline of the body. This is often erroneously described as an enlargement of the metatarsal bone or tissue around the metatarsophalangeal joint. A similar condition of the little toe is referred to as a Tailor's bunion, or bunionette.

The cause is unclear. One proposed idea is that bunions are primarily due to the long-term wearing of particularly tight-fitting shoes with pointed toes.[1] Others believe the problem stems from genetic factors, exacerbated by shoe use.[2] Bunions occur when long-term pressure is applied to the side of the big toe 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 painful. In a survey of people from cultures which do not wear shoes, no cases of bunions were found, lending credence to the first hypothesis.[3]

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.

Signs and symptoms

Illustration depicting a bunion

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.

The presence of bunions can lead to difficulties finding properly fitted footwear and may force a person to buy a larger size shoe to accommodate the width the bunion creates. If the bunion deformity becomes severe enough, the foot can hurt in different places even without the constriction of shoes. It is then considered as being a mechanical function problem of the forefoot.

Pathophysiology

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,[4] other sources concede that footwear only exacerbates the problem caused by the original genetic structure.[2]

Bunions are commonly associated with a deviated position of the big toe toward the second toe, and the deviation in the angle between the first and second metatarsal bones of the foot. The small sesamoid bones found beneath the first metatarsal (which help the flexor tendon bend the big toe downwards) may also become deviated over time as the first metatarsal bone drifts away from its normal position. Osteoarthritis of the first metatarsophalangeal joint, diminished and/or altered range of motion, and discomfort with pressure applied to the bump or with motion of the joint, may all accompany bunion development. Atop of the first metatarsal head either medially or dorso-medially, there can also arise a bursa that when inflamed (bursitis), can be the most painful aspect of the process.

Diagnosis

X-ray showing measurements of HVA and IMA angles of hallux valgus.

Bunion can be diagnosed and analyzed by plain projectional radiography. The hallux valgus angle (HVA) is the angle between the longitudinal axes of the proximal phalanx and the first metatarsal bone of the big toe. It is considered abnormal if greater than 15-18°.[5] The following HVA angles can also be used to grade the severity of hallux valgus:[6]

The intermetatarsal angle (IMA) is the angle between the longitudinal axes of the first and second metatarsal bones, and is normally less than 9°.[5] The IMA angle can also grade the severity of hallux valgus as:[6]

Treatment

Conservative treatment for bunions include changes in footwear, the use of orthotics (accommodative padding and shielding), rest, ice, and pain medications such as acetaminophen or nonsteroidal anti-inflammatory drugs. These treatments address symptoms but do not correct the actual deformity.[7] If the discomfort persists and is severe or when aesthetic correction of the deformity is desired, surgical correction by an orthopedic surgeon or a podiatric surgeon may be necessary.

Orthotics

Orthotics are splints or regulators while conservative measures include various footwear like gelled toe spacers, bunion/toe separators, bunion regulators, bunion splints, and bunion cushions. There are a variety of available orthotics (or orthoses) including over-the-counter or off-the-shelf commercial products and as necessary, custom-molded orthotics that are generally prescribed medical devices.

Surgery

Surgery to remove the bony enlargement and restore normal alignment of the toe joint.
Bunionectomy

Procedures are designed and chosen to correct a variety of pathologies that may be associated with the bunion. For instance, procedures may address some combination of:

At present there are many different bunion surgeries for different effects. The age, health, lifestyle and activity level of the patient may also play a role in the choice of procedure.

Traditional bunion surgery can be performed under local, spinal or general anesthetic. A person who has undergone bunion surgery can expect a 6- to 8-week recovery period during which crutches are usually required to aid mobility. An orthopedic cast is much less common today as newer, more stable procedures and better forms of fixation (stabilizing the bone with screws and other hardware) are used. Hardware may even include absorbable pins that perform their function and are then broken down by the body over the course of months. After recovery long term stiffness or limited range of motion may occur in some patients. Visible or limited scarring may also occur for patients.

See also

References

  1. ↑ Howell, Daniel (2010). The Barefoot Book. Hunter House.
  2. 1 2 "Bunions (Hallux Abducto Valgus)". Footphysicians.com. 2009-12-18. Retrieved 2011-03-20.
  3. ↑ Shulman, Samuel B. (1949). "Survey in China and India of Feet That Have Never Worn Shoes". The Journal of the National Association of Chiropodists. 49: 26–30. Retrieved 27 September 2012.
  4. ↑ "Bunions – Information About Bunion Deformities". Orthopedics.about.com. 2011-01-24. Retrieved 2011-03-20.
  5. 1 2 Rebecca Cerrato, Nicholas Cheney. "Hallux Valgus". American Orthopaedic Foot & Ankle Society. Retrieved 2016-12-30. Last reviewed June 2015
  6. 1 2 Piqué-Vidal, Carlos; Vila, Joan (2009). "A geometric analysis of hallux valgus: correlation with clinical assessment of severity". Journal of Foot and Ankle Research. 2 (1). ISSN 1757-1146. doi:10.1186/1757-1146-2-15.
  7. ↑ Hecht, PJ; Lin, TJ (March 2014). "Hallux valgus". Medical Clinics of North America (Review). 98 (2): 227–32. PMID 24559871. doi:10.1016/j.mcna.2013.10.007.
Classification
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