A bunion is a foot deformity in which the bunion is deflected outward beyond the normal physiological angle, and is one of the most common lesions of the forefoot. In recent years, with the improvement of people’s living standards and lifestyle changes, the incidence of bunions has increased significantly. From the results of physical examination, it is generally believed that a bunion can be diagnosed with a bunion angle of more than 20°.
Etiology
The onset of bunion is associated with a variety of factors. The following are generally considered to be the causes.
①Shoe wear: Wearing shoes is not the only cause of bunions, but wearing narrow, high-heeled shoes is considered to be one of the important external causes of bunions.
②Genetic factors: Many bunion patients have a family history of the disease.
③Foot structural abnormalities: Certain structural abnormalities of the foot, such as flatfoot syndrome, overgrowth of the first metatarsal, overgrowth of the proximal phalanx of the first toe, and inversion of the first metatarsal, can cause bunions.
④Other: bunions can occur after foot trauma due to untreated or improperly treated metatarsal fractures or unbalanced muscle strength of the first metatarsophalangeal joint. In addition, some other systemic diseases such as rheumatoid arthritis, gout and other lesions destroy the normal balance structure of the soft tissues and bone joints of the foot, and bunion deformity can also occur under the action of internal factors and external forces.
Clinical manifestations and examination
1. Physical examination.
After bunion, the medial bony flank of the 1st metatarsal head forms and rubs against the shoe surface to form bursitis, called bunion. In the case of dorsal protrusion of the 1st metatarsal head with bursitis, it is also known as dorsal bunion. Because bunions are often accompanied by lesions in other parts of the foot, such as hammertoes, metatarsalgia, and bursitis of the little toe, some people also refer to bunions as bunion complex or bunion syndrome.
2.Imaging examination.
A weight-bearing X-ray plain film is performed, and the following data need to be measured.
(1) The angle between the first metatarsal of the bunion angle and the midline of the proximal phalanx, with a normal value of less than 15°.
(2) Intermetatarsal angle between the first and second metatarsal stem midline, the normal value is less than 9°.
(3) Distal metatarsal articular surface angle (DMAA) the angle of intersection between the articular surface of the first metatarsal head and the long axis of the first metatarsal: normal is the lateral inclination of the articular surface of the metatarsal head less than 10°.
(4) joint matching whether the joint surface of the first metatarsal head and the proximal phalanx are semi-dislocated, if the sides of the joint are tilted, the joint is mismatched.
(5) Angle between toe bones The angle between the midline of the proximal and distal phalanges of the first toe is normally less than 10°.
3.Grading of bunion according to severity
(1) Mild bunion bunion angle is less than 30° and intermetatarsal pinch angle is less than 13°. The joints are often matched, and the deformity may be caused by an interphalangeal bunion.
(2) Moderate bunions have a bunion angle of 30° to 40° and an intermetatarsal pinch angle of 13° to 20°. The metatarsophalangeal joint is often mismatched (subluxation), and the bunion rotates forward and often causes compression of the second toe.
(3) Severe bunions have a bunion angle greater than 40° and an intermetatarsal joint angle of 20° or greater. The bunion is rotated anteriorly and often overlaps above or below the second toe, and the metatarsophalangeal joint does not match. There is often metastatic pain under the second metatarsal head and there may be arthritic changes.
Treatment
1.Non-surgical treatment
Non-surgical treatment of bunion is divided into four parts.
①Reducing local pressure and wearing loose shoes.
② Reduce swelling and pain. For patients who have formed bunions, physical therapy, hot compresses, and local anti-inflammatory and pain-relieving drugs can be used to reduce symptoms.
③Use orthopedic braces. For patients with mild deformities, silicone cushions can be placed between the bunion and the 2 toes to reduce the bunion and relieve pain. However, there is a risk of compression of the 2 toes. A night splint can also be used to hold the bunion in the inversion position. However, it cannot be used during the day. For more severe deformities, a brace cannot permanently correct the deformity. It can only delay the development of the deformity and relieve pain.
④ Functional exercises. For example, a rubber band can be used to pull the bunion inward.
2.Surgical treatment
If conservative treatment cannot relieve the symptoms of bunion deformity, surgery can be recommended to correct the bunion. The overall goal of surgical treatment is to relieve pain, correct the deformity, and restore the normal function of the foot as much as possible.
The following requirements should be met during surgery.
① Correct the bunion.
(ii) Removal of the medial phalanx of the 1st metatarsal head and the bunion.
③ Correct the enlarged IMA and reset the 1st metatarsal seed bone system.
④Stabilize the medial sequence of the foot.
⑤ Functionally reconstruct the 1st metatarsophalangeal joint with existing osteoarticular structural damage.
⑥Adjustment of the metatarsal head weight-bearing and management of the combined lateral toe lesion.
There are several surgical approaches, but no single surgical approach is appropriate for all bunion patients. The appropriate surgical approach should be chosen based on the patient’s specific situation. In mild to moderate bunions, if the angle between the first and second metatarsals is less than 15°, the medial phalanx of the metatarsal head can be excised and the bunion tendon can be cut or excised. The severed end of the thumb retractor tendon is displaced to the lateral side of the metatarsal head and neck or the metatarsal head and neck is osteotomized and displaced.