Hallux valgus is a complex deformity of the first ray that leads to progressive pain often at the medial eminence of the first metatarsophalangeal (MTP) joint and may also be accompanied by deformities and symptoms of the lesser toes. It is a cause of substantial foot pain; is related to reduced health-related quality of life, impaired balance, altered gait patterns, and an increased risk of falls; and is costly to treat. Hallux valgus is a common condition with an estimated prevalence of 23% in adults aged 18 to 65 years and 35.7% in those older than 65 years with a higher prevalence in females.¹ A number of intrinsic and extrinsic factors that may create a predisposition for the development of hallux valgus have been identified. Intrinsic factors include genetics, osseous anatomy, ligamentous laxity, age, and female gender, whereas extrinsic factors include influence of shoes, that is, constricting footwear and prolonged weight bearing over time.

The condition is often asymptomatic, but pain may arise from wearing of improper footwear, bursitis over the medial aspect of the first MTP joint, or secondary osteoarthritis. While the precise biomechanical etiology of hallux valgus is not well understood, it is known that the medial prominence or bunion is the result of both the medial deviation of the first metatarsal and the lateral deviation and pronation of the hallux. Although debated, hypermobility of the first ray has often been implicated in the development of hallux valgus. The first ray is inherently unstable as its stability depends on several static and dynamic structures at the first MTP and first tarsometatarsal (TMT) joints. The attenuation of the medial supporting structures of the first ray results in medial deviation of the first metatarsal and lateral deviation and pronation of the hallux, causing a progressive varus deformity at the first TMT joint. As the metatarsal head drifts medially, the medial sesamoid lies under the eroded metatarsal ridge and the lateral sesamoid articulates with the lateral side of the metatarsal head in the first intermetatarsal space. The tendons of extensor hallucis longus (EHL) and flexor hallucis longus are carried laterally with the phalanx, thus becoming adductors and exacerbating the deformity.² This sequence results in the prominence on the medial aspect of the first metatarsal head, which can become a major source of pain in hallux valgus.

Additionally, there is a reduction in plantar pressure under the first ray that leads to insufficiency of the first ray and overloading of the lesser rays. This may manifest as pain in a few different ways. First, through a phenomenon called transfer metatarsalgia. If the first ray bears insufficient weight for any number of reasons, then that weight can be transferred typically to the second or third metatarsal heads, resulting in pain associated with the affected metatarsals.³ Transfer metatarsalgia is seen as a result of increased pressure and load transfer to the lateral metatarsal region. A load and pressure transfer from the big toe to the central metatarsal region occurs, indicating the functional impairment of the big toe and the simultaneous worsening of the loading conditions at the other metatarsals.⁴ Insufficiency of
the first ray and overcrowding may also cause deformities of the lesser toes such as corns, calluses, hammer toes, etc., which can become a significant source of pain as well.

Hallux varus is a clinical condition characterized by medial deviation of the hallux at the first MTP joint, phalanx supination, and interphalangeal (IP) flexion.⁵ The cause of this condition is most often iatrogenic, usually resulting from overcorrection during surgery performed for hallux valgus.⁵ Congenital hallux varus is less common with multiple etiologies and may coexist with other foot malformations.⁶ Other causes for the condition include trauma, contracture, systemic inflammatory conditions, Charcot-Marie-Tooth disease, and osteonecrosis of the first metatarsal head.⁵

A comprehensive physical examination is necessary when evaluating patients with hallux
varus deformity. It is critical to determine whether the deformity is flexible, meaning it can be passively reduced, or rigid, meaning it is fixed from long-standing contractures and is currently irreducible. Flexible deformities are often amenable to soft-tissue procedures where fusion may be required in more long-standing rigid or painful deformities.

The chief complaint from patients is often that of dissatisfaction with the cosmetic deformity or problems with shoe fit.⁷ Pain is less likely to be a presenting complaint. However, pain can occur from underlying arthritis, and for this reason, attempts should be made to examine for painful motion or crepitus of the MTP joint, while the greater toe is held in a reduced position. In cases of long-standing deformity, a dorsal contracture at the MTP joint may develop, making it very difficult for the patient to maintain contact between the greater toe and the ground and resulting in functional impairment and weak toe push off.