A hallux valgus deformity, commonly called a bunion, is when there is medial deviation of the first metatarsal and lateral deviation of the great toe (hallux). The condition can lead to painful motion of the joint and shoe wear difficulty. It is important for a treating physician to understand the pathogenesis and surgical treatment options to correct hallux valgus deformities to provide the utmost care for patients with this painful forefoot deformity.
There is continued debate over the association of poor-fitting footwear and bunions. Many experts feel high-heeled shoes with a small toe box or tight-fitting shoes do not cause the deformity. However, most agree footwear can exacerbate the problem by keeping the hallux in an abducted position. Hallux valgus has numerous recognized etiologies, including biomechanical, traumatic, and metabolic factors. Some cases are congenital, secondary to the sloping orientation of the first tarsometatarsal joint.
Bio-mechanical instability is the most common etiology and is associated with flat feet, gastrocnemius contracture, excessive flexibility of ligaments, forefoot varus, and abnormal bone structure. Arthritic conditions associated with hallux valgus include gout, rheumatoid arthritis, and psoriatic arthritis. Connective tissue disorders with ligamentous laxity can develop hallux valgus deformities, including Marfan’s syndrome, Ehlers-Danlos syndrome, and Down syndrome. Neuromuscular disorders, such as cerebral palsy and Charcot Marie Tooth (CMT), are often associated with rigid bunions. Finally, traumatic causes for hallux valgus include malunited fractures, dislocations, and severe soft-tissue sprains around the first MTP joint.
Patients present to the clinic with a variety of complaints. Pain typically is localized to over the prominent medial eminence. Patients may have an enlarged bursa over the medial eminence with inflamed skin or callus. The frequency or severity of pain may have recently progressed, and pain with activity will often bring these patients in to be evaluated. The patient may have recognized an increase in the size of the deformity. Difficulty with finding comfortable shoe wear is common.
Examination of a hallux valgus deformity involves inspection of foot both standing and non-weightbearing. The presence of a flatfoot or cavus deformity, metatarsus adductus, associated lesser toe pathology, and EHL contractures can be best interpreted having the patient weight bear. Hallux MTP range of motion is evaluated and the position of the great toe is inspected in both the transverse and frontal planes. First ray mobility is determined at the first tarsometatarsal joint. Plantar keratosis under the hallux IP joint indicates excessive pronation, whereas keratosis under the second metatarsal head is associated with a transfer lesion, often seen with a short first metarsal or long second metarsal. Associated lesser toe deformities, such as hammertoes, cross-over toe deformities, and transfer metatarsalgia pain, should be evaluated for as well.
Cosmetic correction is not a correct indication for surgery of a hallux valgus deformity. For surgical treatment to be indicated, the patient must have pain that is not alleviated by a simple change of shoes or other conservative treatments. The type of surgical treatment is usually dictated by the degree of the deformity on radiographs as well as physical exam findings.
Over 150 different operations have been described for the treatment of hallux valgus. The goals of surgery are soft tissue and bone realignment. For mild deformities, resection of the prominent medial eminence (exostectomy or bunionectomy), distal metatarsal osteotomies, and realignment of the soft tissues surrounding the metatarsophalangeal joint are commonly employed. For more severe deformities, surgeons utilize first metatarsal shaft or proximal osteotomies to achieve a more powerful correction. When patients exhibit hypermobility at the first tarsometatarsal joint, a fusion of this joint ( Lapidus procedure) provides a reliable correction. Arthrodesis of the first metatarsophalangeal joint is utilized for severe deformities, spastic or rigid deformities, and associated arthritis. With a high number of different operations performed and few with high levels of evidence, a recommendation for a particular treatment is not possible.