The American Orthopaedic Foot and Ankle Society Hallux Metatarsophalangeal-Interphalangeal Rating System, commonly referred to as the AOFAS score, is a clinical tool used to evaluate the condition of the foot and ankle, specifically the hallux metatarsophalangeal and interphalangeal joints. This calculator is primarily used in patients with foot and ankle disorders, including but not limited to hallux rigidus, hallux valgus, and other deformities or injuries of the big toe.

The AOFAS score provides a comprehensive assessment of the patient's foot and ankle condition, taking into account pain, function (including limitation of activity and walking distance), and alignment. The score ranges from 0 to 100, with higher scores indicating better foot and ankle health.

The AOFAS score is not recommended for use in patients with systemic conditions that may affect the foot and ankle, such as rheumatoid arthritis or diabetes, as these conditions may confound the score. It is also not suitable for use in children or in patients with cognitive impairment who may not be able to accurately report their symptoms.

American Orthopaedic Foot and Ankle Society Hallux Metatarsophalangeal-Interphalangeal Rating System (AOFAS score)

# Criteria
 ## Pain
A. None (+40)
B. Mild, occasional (+30)
C. Moderate, daily (+20)
D. Severe, almost always (+0)
## Function, activity limitations
E. No activity limitations (+10)
F. Limitations on recreational activities (+7)
G. Some limitations on daily and recreational activities (+4)
H. Severe limitations on daily and recreational activities (+0)
## Function, footwear requirements
I. Can wear conventional shoes (+10)
J. Comfort footwear and shoe insert required (+5)
K. Modified shoes or brace required (+0)
## Function, metatarsophalangeal joint motion (dorsiflexion plus plantarflexion)
L. Normal or mild restriction (>= 75 degrees) (+10)
M. Moderate restriction (30-74 degrees) (+5)
N. Severe restriction (< 30 degrees) (+0)
## Function, interphalangeal joint motion (plantarflexion)
O. No restriction (+5)
P. Severe restriction (< 10 degrees) (+0)
## Function, metatarsophalangeal-interphalangeal stability (all directions)
Q. Stable (+5)
R. Unstable or able to dislocate (+0)
## Function, callus or corn/clavus
S. No or asymptomatic callus or corn/clavus (+5)
T. Painful callus or corn/clavus (+0)
## Alignment
U. Good, well-aligned (+15)
V. Fair, mild-to-moderate malalignment (+8)
W. Poor, severe malalignment (+0)

# Conditions
- score >= 90
- score >= 75
- score >= 60
- score <= 59
- score == 0