Hallux valgus is one of the most common disorders of the foot, and is the most prevalent disorder of the bunion. Hallux valgus is a medical term, in addition to the terms “bigfoot” and “big goblet crutch”. In English, bunion also refers to a bunion, specifically the protrusion on the inside of the foot when a bunion occurs. A bunion is defined as an outward deviation of the bunion, where the angle between the proximal phalanx of the bunion and the first metatarsal is greater than 15°. This angle is called the bunion angle (Halluxvalgusangle, HAV). Hallux valgus is a morphologic diagnosis and does not properly define the pathologic process of a bunion. (Note: thumb is known as “?” The degree of bunion can be understood in general by referring to the self-test chart: A is normal, B has a bunion angle of about 15°, and C, D, and E have bunion angles in 15° increments.
Etiology
The most important causes of bunions are currently considered to be genetics and shoe wear, in addition to flat feet and an excessively long or short 1st metatarsal bone are also relevant factors. There is a clear genetic predisposition to bunions, usually in female members of the family, with a sex ratio of male to female = 1:9-15.
In the analysis of Sim-Fook and Hodgson’s survey, 33% of the 118 people who wore shoes had bunions, while only 2% of the 107 people who did not wear shoes had bunions. kato reported a significant increase in the incidence of bunions in the Japanese population due to an increase in the number of people wearing Western-style shoes. The forefoot is significantly restricted when wearing high heels, which makes it easier for bunions to form.
Bunion is a condition that occurs after skeletal development has matured. There is a correlation between bunions and flat feet, but the causal relationship needs to be further investigated. The peak incidence of bunions is between the ages of 20-30 and 50-60. Younger patients are associated with genetics and wearing high heels; older women in their 50s and 60s are associated with genetics and postmenopausal endocrine changes.
Anatomy and pathophysiology
Anatomically, the bunion deformity includes anatomical changes such as
1st metatarsal inversion.
External rotation of the bunion, with posterior rotation.
Bunion retractor, contracture of the lateral joint capsule.
dislocation of the seed bone relative to the 1st metatarsal head.
loss of normal anastomosis of the 1st metatarsophalangeal joint.
formation of the medial bony tuberosity of the 1st metatarsal, complicated by bunion.
Complication of the 1st metatarsophalangeal joint with osteoarthritis.
Foot disorders caused by bunions also include.
Hammertoe of the 2nd-4th toes (Hammertoe).
Metatarsophalangeal joint subluxation (MTPjointsubluxation).
cross-toedeformity (cross-toedeformity).
Metatarsalgia (Transfermetatasalgia).
The 1st metatarsophalangeal joint consists of two long tubular bones together with the seed bone and the surrounding ligaments, tendons and soft tissues. There are no muscle attachments at the 1st metatarsal, whereas the proximal phalanges have a large number of muscle and tendon attachments, mainly: the bunion, bunion extensor, bunion flexor, and bunion extensor muscles. On the metatarsal surface of the 1st metatarsophalangeal joint, there is a tough metatarsal plate – consisting of the joint capsule, the bunion tendon, the bunion extensor, the metatarsal portion of the bunion extensor, and the medial and lateral collateral ligaments. On the metatarsal side, on the thumb flexor tendon, there are two seed bones that form a metatarsal seed joint with the first metatarsal. The two seed bones are separated by the bony crest of the metatarsal bone and are crossed by the long thumb flexor tendon between them.
The shape of the 1st metatarsal head varies from person to person, with the rounded metatarsal head having a less stable articular surface. The angle between the articular surface of the first distal metatarsal and the axis of the first metatarsal is known as the Distalmetatarsalarticular Angle (DMAA), which varies from person to person.
Bunion development is a gradual process.
(a) First the bunion is subjected to an outward force, causing the proximal phalanx of the bunion to form an angle with the 1st metatarsal.
After the formation of the angle, the tendons of the long bunion extensor and bunion retractor muscles comprise the muscle forces that aggravate the deformation of the bunion during the gait lift phase. This causes the medial joint capsule to extend and bunion and metatarsal head osteophytes to develop; at the same time the lateral joint capsule tightens, making it difficult to recover from valgus.
As the metatarsal head is inwardly retracted while the seed bone remains in the tendon relative to the foot, a relative dislocation of the seed bone occurs.
With the metatarsal inversion and bunion valgus, the bunion extensor muscle slides underneath the metatarsal head and rotates the bunion through its proximal bunion stop pulling action, forming a bunion rotation back.
After the onset of bunion, the forefoot becomes wider and it is difficult to wear shoes. The medial expansion of the bunion joint is mainly formed by the bony bulge on the medial side of the 1st metatarsal. The expanded tissue aggravates the friction after wearing shoes and forms a bunion. In some cases, the enlargement is due to a large angle of inclination of the joint surface, forming a medial bone protrusion, and the 1st metatarsal bone is tilted inward, forming a medial bunion protrusion.
There is a special category of bunion patients in which the valgus deformity is caused by ectropion of the interphalangeal joint of the bunion. In these patients, the angle between the distal and proximal phalanges of the bunion is too large, while the degree of inversion of the 1st metatarsal is not severe, and although the cosmetic presentation is more severe, the surgical treatment is different.
Clinical manifestations
The most significant clinical manifestation of a bunion is pain, and complaints usually include
Pain at the bunion.
Pain in the 1st metatarsophalangeal joint.
Pain under the 2nd and 3rd metatarsal heads of the foot with callus.
pain under the seed bone.
Numbness of the skin.
Pain, deformity of the 2nd toe – hammer toe, riding across the toe, dislocation of the 2nd metatarsophalangeal joint.
Pain, deformity of toes 2-4.
As the quality of life improves, the aesthetic impact on the foot is one of the reasons why patients seek medical attention.
Physical examination
The clinical examination begins with a medical history, noting whether the patient has a history of previous surgery and whether there is a history of trauma. By taking the history, it is important to understand the patient’s expectations for bunion treatment. Patients who report unrealistic expectations also tend to have poor treatment outcomes. It is also important to have a history of diabetes mellitus, rheumatoid arthritis, and systemic diseases.
The patient’s entire foot should be examined during the physical examination. This includes the hindfoot, the arch, and each toe of the forefoot. Check for signs of neuropathic pain.
The patient’s bunion should first be examined for the degree of bunion and whether it can be manually repositioned. After repositioning, check the mobility of the metatarsophalangeal joint and determine the joint surface tilt and joint anastomosis. Note whether the patient’s bunion is rotated or not. The bunion is painful or not. The interphalangeal joints should be examined for pain and valgus.
Check for normal mobility of the 1st metatarsophalangeal joint. Maximum passive dorsiflexion can usually be 65°-75° and maximum passive plantarflexion is 15° or more. A maximum passive dorsiflexion of less than 65° is usually a sign of bunion stiffness. There is no pressure pain in the joint space. Pressure pain suggests the presence of osteoarthritis and cartilage can be damaged to varying degrees.
The patient should be noted for seed bone pain, and x-ray examination may also reveal seed bone hyperplasia.
Check the patient’s metatarsal cuneiform joint for laxity. The patient is instructed to pay attention to the changes of the medial arch when standing. When examining the metatarsocuneiform joint, the patient is in a sitting position, pinch the 2-4 metatarsals with one hand and the head of the 1st metatarsal with the other hand and move up and down, if the mobility exceeds 7°-10°, the laxity of the metatarsocuneiform joint cannot be excluded. An objective criterion for evaluating metatarsocuneiform joint laxity is lacking.
Check 2-4 toes for hammertoes, riding toes, painful calluses under the 2nd and 3rd metatarsal heads, and painful, dislocated 2nd metatarsophalangeal joints.
Check the dorsalis pedis artery pulsation and nerve sensation in the foot, and note whether the patient’s pain is neurological and not caused by a bunion.
Ancillary examinations
A weight-bearing X-ray of both feet should be taken during the bunion examination. The weight-bearing X-ray is the main test for preoperative and postoperative evaluation of bunions.
It has been reported that the 2nd metatarsal is noted to be the mid-axis of the foot with a fixed relative position during x-ray measurements; however, patients with severe bunions have metatarsal inversion, a condition discussed in a separate article. The axis of the backbone was determined according to the measurement method reported by CoughlinM.J.: the reference point of the axis was taken from the 1st and 2nd metatarsals at 1cm and 2cm from the most distal articular surface and the base of the proximal metatarsal to make a vertical backbone straight line and take the midpoint; the proximal phalanx of the bunion was taken from the distal and proximal ends at 0.5cm and 1cm and then took the midpoint to make the axis.
The parameters that need to be obtained after measuring the orthogonal x-ray are
Bunion angle (HAV) – the angle between the axis of the 1st metatarsal and the axis of the proximal phalanx of the bunion, normal is 15° or less.
Intermetatarsal angle (IMA) – the angle between the axes of the 1st and 2nd metatarsals, normally less than 9°.
Distal metatarsal articular surface inclination angle (DMAA, PASA) – the angle between the joint surface line of the 1st metatarsal head and the 1st metatarsal axis, normal lateral inclination is less than 7.5°.
Angle of interphalangeal exostosis (HAIA) – the angle between the proximal and distal phalanges of the bunion. It is usually less than 10°.
The measurement should also take note of the anastomosis of the 1st metatarsophalangeal joint and the presence of osteoarthritic manifestations on the joint surface. The seed bone is dislocated and there is no variation in the seed bone. If the patient has lateral submetatarsal pain, note the length of the 1st metatarsal and whether it is relatively too short. Also note the presence of arthritic changes in the 2nd and 3rd metatarsophalangeal joints.
An axial examination of the seed bone can also be performed to evaluate the seed bone dislocation, and the position of the seed bone should be considered during surgery to allow for the possibility of postoperative complications of seed bone pain if the dislocation cannot be surgically corrected.
Treatment of bunion
Conservative treatment
Shoe replacement is the most important way to influence the outcome of conservative treatment. Patients wearing comfortable shoes that fit well are the main influencing factor in the success or failure of conservative treatment of bunions. If the pain is predominantly red and painful in the medial bunion, wear shoes with a wide foreshortening to reduce compression and friction. If the patient has submetatarsal head or subseed bone pain, a forefoot decompression foot pad should be added to reduce pressure to alleviate the pain. If the pain is from 2-4 toes, hammertoe pads, small toe paracarpal pads, and interdigital pads can be used to reduce friction and pressure depending on the cause of the pain.
Surgical treatment
Surgical treatment is available for all patients for whom conservative treatment is ineffective. Factors to be considered in treatment are
1. what is the cause of the patient’s pain and what is the surgical solution to the patient’s pain problem.
2. bunion surgery to treat the bunion if it is one of the causes of the pain
3. when the bunion causes a deformity of the lateral 2-4 toes, the bunion needs to be corrected first and the deformity of the lesser toe corrected at the same time.
4. preoperative weight-bearing X-ray measurements should be performed to observe the deformity characteristics of the x-ray joint, metatarsal, seed bone and little toe before deciding on the surgical approach
5. preoperative evaluation of the patient’s foot nerve and blood flow situation to see if it is operable, if there is nerve-induced pain, postoperative does not relieve the patient’s pain
6. there are certain complications arising from the surgery, and the athlete may not be able to return to the field of play after the surgery due to limited movement of the 1st metatarsophalangeal joint. In addition there may be a recurrence of deformity after surgery, especially in adolescent patients. Possible legacy of postoperative pain.
7. other common complications include: bunion, relative shortening of the 1st metatarsal, metastatic metatarsalgia, infection in the surgical area, and dermatomal neuritis
8. irritation of the skin by the internal fixation may also occur
9. After postoperative x-ray angle correction, there may be a residual enlargement of the medial bunion, which is scar tissue and may decrease in size over time.
Contraindications to surgery.
Surgery is contraindicated for infected metatarsophalangeal joints, poor blood flow, poor patient compliance, or unrealistic expectations of surgery, because surgery has its own limitations. Surgery is also contraindicated when there is osteoarthritis in the first metatarsophalangeal joint. Patients with laxity of the 1st metatarsocuneiform joint should be considered for Lapidus surgery or fusion of the metatarsocuneiform joint.
It is important to talk to the patient before surgery to understand what the main cause of foot pain or discomfort is, and to confirm this with physical examination and x-ray. If the decision is based solely on physical examination and x-ray, it may leave a legacy of problems and persistent postoperative pain.
In patients with a history of previous bunion surgery, the patient’s foot, joint mobility, plantar callus and force distribution should be carefully examined preoperatively. x-ray examination should be noted for the presence of bunion inversion, shortening of the 1st metatarsal, absence of seed bone, and destruction of the articular surface of the 1st metatarsal head. Such cases are not necessarily suitable for bunion orthopedic surgery.
There are many bunion surgery options, such as Chevron, Reverdin, Ludloff, Scarf, Lapidus osteotomy, and Akin osteotomy of the phalanx. The commonly used surgical procedures are selected based on the size of the angle between the 1st and 2nd metatarsal bones and the degree of articular surface anastomosis, refer to the bunion surgery options section of the article.
Post-operative care
Usually bunion surgery in China is performed inpatient, usually with a relatively short hospital stay of about 4-7 days. For patients with more toe deformities and more surgeries performed at the same time, postoperative antibiotics should be used prophylactically and the blood flow to the toes should be kept in mind.
After forefoot surgery, you can wear forefoot weight-reducing shoes to walk on the ground, and walking is limited to activities such as washing and toileting. Cold compresses are feasible after surgery to reduce pain, and oral pain medications can be taken to reduce postoperative discomfort.
X-ray examination is performed on the postoperative day or the first postoperative day to pay attention to the postoperative correction of the angle and the anastomosis of the joint surface. The wound will be changed within 24 hours after surgery, the stitches will be removed in 14 days, and the X-ray will be rechecked after 1 month, and the sports shoes can be changed at 6 weeks.