Hallux Valgus

The term “Hallux valgus”, was originally coined in 1871 by Carl Hauter. The understanding of the aetiology and pathogenesis of hallux valgus in the early 19th century was inadequate at best. It was believed to be a deformity primarily caused by enlargement of soft tissues. Because of this poor understanding, initial management of hallux valgus (HV) deformity remained unsatisfactory. Reverdin presented his successful operation in 1841 which consisted of an incision medial to the Extensor Hallucis longus (EHL) tendon. The periosteum was then incised, an exostectomy performed and the bone was sutured with cat gut. The Reverdin operation is the forerunner of the approximately 130 interventions that can be listed nowadays. Some of these operations are very successful, whilst many others are but poor imitations of lesser successful operations.

Hardy and Clapham from UK in 1951 accurately linked the increase in intermetatarsal (IMA) angle between the 1st & the 2nd ray with the occurrence of HV deformity. This formed the basis of different surgical algorithms based on correcting the IM angles & reducing the overall width of the widened foot. Correction of the joint incongruity forms the other part of the surgical procedures requiring soft tissue balancing and distal metatarsal articular angle (DMAA) correction.

According to the National Centre for Health Statistics in the United States of America, hallux valgus affects 1% of adults in the United States. According to Gould, the incidence of HV increases with age, with rates of 3% in persons aged 15-30 years, 9% in persons aged 31-60 years, and 16% in those older than 60 years. The incidence is higher among females, with a ratio of 2:1 to 4:1. Hallux valgus accounts for a large number of orthopaedic referrals for forefoot discomfort. It has been documented widely that HV deformity is secondary to ill fitting shoes, and particularly afflicts females. Coughlin and Jones analysed the demographic characteristics and the aetiological factors giving rise to moderate and severe hallux valgus. They studied 104 patients with a total of 124 feet. 92% were females and 8% male. They documented bilateral hallux valgus in 84% of cases. Although the role of genetic predisposition has been noted, with evidence to suggest familial tendencies, there is no conclusive evidence regarding the association with race.

Aetiology and Pathogenesis
The aetiology is multifactorial, there appears to be some association with high heel shoes, a narrow toe box but this is not as strong as previously thought. Genetics plays an important role with up to 68% of cases having a familial tendency. The role of pes planus is more controversial. Although pes planus is not associated with hallux valgus, the presence of pes planus is associated with a faster deterioration in the deformity. Hypermobility of the first ray may be a factor, but what is certain, is that hypermobility of the first ray is commonly associated with a painful hallux valgus. Other aetiological factors include collagen deficiency, rheumatoid arthritis, trauma and neurovascular disorders.

Stephens clearly described the pathogenesis of hallux valgus in 1994. The medial tissues of the first metatarsophalangeal joint are weakened followed by erosion of the ridge of the head of the metatarsal head between the medial and lateral sesamoids. The proximal phalanx drifts into valgus and the metatarsal head drifts into varus giving rise to the apparent prominence of the medial exostosis or the painful bunion. The medial bursa increases in size in response to the pressure exerted by the friction of shoes over the prominence. As the medial tissues attenuate further, the metatarsal head displaces medially. The lateral sesamoid articulates with the lateral side of the metatarsal head in the first intermetatarsal space. The Extensor hallucis longus and the flexor hallucis longus are carried laterally with the phalanx and along with the adductor hallucis and the lateral head of the flexor hallucis brevis have a summative effect exacerbating the adduction. These tendons contract along with the lateral joint capsule. The abductor hallucis and the medial head of flexor hallucis brevis lose their abductor moment. This imbalance causes dorsiflexion and pronation of the first toe, and the loss of contact with the toe's pulp, thus becoming non-functional.

Clinical History
Most common complaints include difficulty finding comfortable shoes, medial eminence pain, unsightly deformity and transfer metatarsalgia. Although hallux valgus may start from adolescence, the condition is most commonly found among women above thirty years of age. Patients may present with a short history or may have endured many years of pain and discomfort before presenting with a severe deformity. The deformity is believed to be progressive, varying in presentation from a developing bunion to complete subluxation of the first metatarsophalangeal joint. Pain is usually associated with the friction caused by ill fitting shoes over the subcutaneous bunion.

Associated callosities over the toe deformities and under the metatarsal head may be the first presenting symptoms from a laterally deviated hallux.

Clinical Examination
The patient is examined in both weight bearing and non weight bearing positions paying attention to the gait pattern and the pattern of shoe wear which may be different in painful situations. Shoe friction may cause an area of soreness of skin, erythema, thickening or even a painful inflammation of the bursa or of the tissues surrounding the first MTPJ. Pressure effects over the medial dorsal cutaneous nerve may cause a painful neuritis. The sole of the foot is best assessed with the knee extended to check for callosities and neuromas. The normal movement of the MTP joint occurs in a saggital plane while the deformity in HV causes the motion to occur in an oblique fashion. Depending on the degree of the deformity the big toe may override the 2nd toe. The degree of correction at the MTPJ is noted as a stiffer joint may require a bigger lateral release or shortening of the metatarsal. Hind foot deformity and tightness of the Achilles tendon may adversely affect the forefoot symptoms. Heel pronation is believed to cause first ray hypermobility. This in turn causes increase in the IMA angle.

Hallux valgus can be associated with other forefoot deformities including hammering of the second toe, metatarsalgia, Morton's neuromas, forefoot pronation, limited ankle dorsiflexion and ingrown toenails.

Radiographic Assessment
Plain films should be obtained in an anteroposterior, lateral (weight bearing) and oblique views. Features to look for in plain films include;

  1. Medial prominence of the first metatarsal head. This feature may be secondary to an increased Intermetatarsal angle with or without hypertrophy of the medial condyle. Further features may include erosions of the metatarsal head. There may be associated narrowing and degenerative changes at the MTPJ.
  2. Hallux valgus angle (HVA). This angle is the angle formed by the lines bisecting the proximal phalanx of the great toe and the first metatarsal in the AP film. An angle greater than 19
    Categories: ARTICLES, Uncategorized

About Author