Degree of bone deformity caused by a bunion

Bunions may be classified by the degree of bone deformity. This is usually determined by measuring the bunion angle and the intermetatarsal angle and by determining the location of two tiny bones (sesamoids) that normally lie under the big toe joint. Any necessary measurements and X-rays are taken while standing, so that the toe and foot are bearing weight.

The following table classifies bunions according to severity.¹

Classification of bunions

Severity	Degree of bunion angle	Degree of intermetatarsal angle	Dislocation of sesamoids
Normal	Less than 15º	Less than 9º	-
Mild	15º to 19º	9º or 11º	Less than 50%
Moderate	20º to 40º	12º to 15º	50% to 75%
Severe	40º or more	16º or more	75% or more

Citations

1. Coughlin MJ (1997). Hallux valgus. Instructional Course Lectures, 46: 357–391.