First metatarsophalangeal angle

Last revised by Leonardo Lustosa on 16 Jan 2023

The first metatarsophalangeal angle, also known as hallux valgus angle (HVA) or hallux abductus angle, is a measurement used to assess the presence and severity of the alignment of the first metatarsophalangeal joint on a weight-bearing dorsoplantar radiograph of the foot.

The angle between the axis of the metatarsal bone and the proximal phalanx of the great toe is measured 1,2. The axis of both bones is defined either by bisection of head and base of both bones also referred to as center base/center head method or by bisecting the metatarsal shaft at two different points apart from each other of the diaphysis also referred to as shaft bisection 2.

An angle of >15° indicates hallux valgus. A common grading scheme of hallux valgus in consideration of the first metatarsophalangeal angle is 3:

  • normal: <15°
  • mild: 15-20°
  • moderate: 20-40°
  • severe: >40°

However, for proper radiographic evaluation of the hallux valgus not only the first metatarsophalangeal angle but also the first intermetatarsal angle (IMA) should be included in the assessment.

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