What is Hallux Abducto Valgus?
Hallux abducto valgus (also called hallux valgus or bunion) is a combined foot deformity characterized by lateral deviation of the great toe (hallux) away from the midline of the body and medial deviation of the first metatarsal bone, creating a prominent bump on the inner side of the foot at the first metatarsophalangeal joint. 1, 2
Anatomical Components of the Deformity
The deformity involves multiple structural changes:
- Lateral deviation of the great toe (hallux) toward the second toe and away from the body's midline 3, 2
- Medial deviation of the first metatarsal bone (metatarsus primus varus), which creates the characteristic bunion prominence 3, 1
- Frontal plane rotation of the first metatarsal is increasingly recognized as an important component that has historically been underappreciated in treatment planning 1
- Malpositioning of the first metatarsophalangeal joint results from these combined angular deformities 2
Clinical Presentation
The deformity manifests with specific physical findings:
- Visible prominence (bunion) on the medial aspect of the first metatarsal head that can create pressure points and shoe conflict 3
- Pain and restricted mobility at the first metatarsophalangeal joint are common symptoms 3
- Diagnosis is typically made by physical examination alone, though imaging is important for assessing severity and ruling out other conditions 3
Epidemiology
Hallux valgus is extremely common:
- Prevalence is 23% in adults aged 18-65 years and increases to 36% in those over 65 years 3
- Women are more frequently affected than men across all age groups 3
- Onset typically occurs between ages 30-60 years 3
Associated Conditions and Risk Factors
The deformity is associated with specific foot characteristics:
- Foot deformities including bunions (hallux valgus), hammertoe, claw toe, flatfoot (pes planus), and severe high-arch foot (pes cavus) increase risk for foot ulcer development, particularly in patients with peripheral artery disease 4
- Hallux rigidus (degenerative arthritis of the first metatarsophalangeal joint) is the second most common cause of pain in this joint and can coexist with hallux valgus 3