what are bunions ? bunions on feet /hallus valgus
Hallus valgus . Bunions on feet / what are bunions?
Hallus valgus is also known as a bunion. Hallus valgus is presented with lateral deviation of the big toe (which is known as the first digit) and medial deviation of the first metatarsal head. This will result in the formation of the first metatarsal median prominence eminence. Progressively first metatarsophalangeal joint subluxation may also happen. A bunion is mostly affecting the musculoskeletal system and skin.
In term of epidemiology, hallus valgus is predominantly affecting adult more than children and female is the main target rather than male. The prevalence increases with age.
The etiology or risk factors for developing hallus valgus are familial genetical predisposition , pes planus, contracture of the achilles tendon, pointed shoes or tight fitting shoe ( improper footwear ) , joint hyper elasticity, secondary toe amputation and metatarses primus varus.
The associated condition may include ingrowing toenails, hammertoe, deformity of the second phalanx, first metatarsophalangeal joint medial bursitis, a pronated foot, plantar callus, ankle equinus and central Metatarsalgia.
In terms of pathology, there is a medial displacement of > 40 degree and dorsal angulations of the first metatarsal bone with the toe being displaced laterally. The prominent metatarsal head will exert a pressure on the overlying soft tissue which leads to the formation of the bunion (bursa due to friction) and synovial hypertrophy. This will follow later with secondary osteoarthritis mostly affect the elderly.
In terms of signs and symptoms, patient tends to be asymptomatic and diagnosis is made only from the clinical examination. Radiography approach is beneficial for the purpose of staging.
Sometimes patient may complain of pain as well as deformity of the big toe (first digit) when they try to fit into their shoe. On inspection, the patient has an impaired gait with a wide forefoot and displacement of the big toe above may be above or below the second toe and lateral deviation of the other digits. The bunion may appear inflamed or ulcerated on the medial sides of the foot. The first metatarsal is eminence. Callus which is painful develop on the second toe. Skin keratoses present under the metatarsal head and the increase in the angle of the valgus at the first metatarsophalangeal joint. There will be a reduction in the range of movement of the first metatarsophalangeal joint due to the secondary osteoarthritis.
The physical examination performs mostly involved observation and inspection. The patient is observed while standing and sitting as the weight of the patient may accentuates and worsen the deformity. Assess and look for ant rotation of the first digit (big toe) and measures the degree of hallus valgus. This is followed by an assessment of the range of movement either actively or passively at the metatarsophalangeal joint as well as the congruence of metatarsophalangeal joint by passively corrected the deformity. The gait of the patient as well as the neurovascular status of the foot is also need to be assessed.
The most common form of investigation is a radiological imaging study. These include weight bearing, oblique, and lateral as well as anteroposterior radiographs. The radiographs are taken and the measurement of Hallux abductus angle, intermetatarsal angle, medial prominence of the first metatarsal head and congruency of the metatarsophalageal (MTP joint) are taken.
The Hallux abductus angle should normally be < 20 degree. It is identified as the intersection of the lines that bisect and pass through the proximal phalanx and first metatarsal.
The intermetatarsal angle should be normally < 10 degree. It is identified as the intersection line that passes through the first and second shaft of the metatarsal bone.
The median prominence of the first metatarsal head image is inspected and any squaring as well as erosion should be noted.
The congruence of the MTP joint is assessed. No lateral subluxation detected of the proximal phalanx on the metatarsal head indicates congruent joint.
The hallus valgus is staged based on the radiological finding:
In stage 1 - The intermetatarsal angle is less than 12 degree, the hallus abductus angle is less than 25 degree and the joint is deviated or congruent with or without hallux deformity.
In stage 2 - The intermetatarsal angle is less than or 16 degree, the hallus abductus angle is more than or 25 degree and the joint is deviated, congruent or subluxed with or without hallux deformity.
In stages 3 - The intermetatarsal angle is more than 16 degree, The halus abductus angle is more than 35 degree and the joint is deviated or subluxed with or without hallus deformity as well as joint arthrosis.
The differential diagnosis of hallus deformity includes infection ( osteomyelitis and septic arthritis ) , disorders of the tendon ( rupture of the tendon, tenosynovitis and tendinosis) , trauma ( stress, fracture, Sesamoiditis, turf toe ), joint disorder ( gout, rheumatoid arthritis and osteoarthritis ) as well as foreign body , granuloma, ganglia and bursitis.
Hallus valgus is a condition which requires treatment. It will not heal without treatment. Surgical treatment is more beneficial than conservative treatment in improving the outcome.
The most common conservative approach in treating hallus valgus may include proper footwear that able to reduce the pressure on the MTP joint ( metatarsophalangeal joint ) such as wide shoes or low heeled shoes (Shoe’s modification). Introduction of foot insert (orthoses) which may alter the abnormal rotation of the foot. Night splinting is introduced with hope to balance the supporting ligaments. Intrinsic foot muscle strength will improve with stretching exercise. Inflammation can be reduced with ice and to decrease the MTP joint (metatarsophalangeal joint) friction bunion pad is used.
Mangold ointment is a form of alternative or complementary medicine that will reduce the swelling and pain of the soft tissue over a period of 8 weeks. Non steroid anti inflammatory drugs are taken to reduce pain and relieve the swelling.
Surgery is only performed if the conservative treatment fails to improve the patient symptoms (severe pain) and dysfunction of the joints. The patient should be referred to Podiatric feet and ankle surgeon. The outcome of the surgery may include the big toe may not be straight and the patient unable to fit into a smaller shoe. The most common surgical procedure are Mitchell‘s operation and Keller‘s operation. Mitchell’s operation is performed in younger people and adolescent. Mitchell’s operation involved performing osteotomy of the neck of the metatarsal bone and medial displacement of the metatarsal head.Keller’s operation is performed for elderly people. In this procedure the dorsal and medial exostoses as well as proximal third of the proximal phalanges are excised to form a fibrious ankylosis.
Another surgical treatment may include fusions of the first metatarsophalangeal joint ( MTP joint ) by arthrodesis and removal of the joint and replace it with a prosthesis ( arthroplasty ) . Bunionectomy / exostectomy that involve removal of the medial body prominence of the MTP joint are performed. Osteotomy and realignments can also be performed as well as Lapidus procedure which involves a fusion that is performed at / near the first metatarsophalangeal joint (MTP joint). Manipulation of the soft tissue is also performed to alter the function and structure of the tendons and ligaments.
The outcome from hallus valgus is influenced by the modality of the treatment. 90% of adolescent may have a success rate in reconstructive operations.
The complication of hallus valgus may include deformity, pain, thickening of the synovial and bursitis over the MTP joint as well as hyperostosis, plantar keratosis and secondary osteoarthritis. Other complication may also occur from the treatment of hallus valgus such as in Keller‘s operation, that include excessive shortening of the hallus, recurrence of the deformity, metatarsalgia and stiffness of the joint. Arthrodesis of the MTP joint (metatarsophalangeal joint) may result in failure of fusion, malposition and intertarsophalangeal osteoarthritis. Other complications are hallus varus, decrease sensation over the phalanx or the metatarsal head, recurrence of the bunion and early swelling.
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