ACFAS Scoring Scale User Guide

The first metatarsal declination angle is drawn from the lateral radiograph. It is the angle formed by the bisection of the first metatarsal and a line parallel to the ground supporting surface.

(A) The fourth-fifth intermetatarsal angle may be derived by the angular relationship of the bisection of the fourth and fifth metatarsals. (B) An alternative method using a tangent to the medial surface of the fifth metatarsal has been proposed to reduce error from lateral bowing that may occur in the distal fifth metatarsal.

Metatarsal length relationships can be assessed by drawing angular tangents from a perpendicular drawn to the second metatarsal bisection intersecting at the distal articular surfaces. Four metatarsal tangent angles are defined: M1-2, M2-3, M2-4, and M2-5.

The frontal plane angular deformity between the lower leg and foot may be assessed on the long leg calcaneal view with measurement of the angular deviation of the bisection of the tibia and the bisection of the calcaneus.

The calcaneus lies lateral to the weightbearing axis of the lower leg. This may be assessed radiographically by the calcaneal translational displacement, which is the distance between the longitudinal axis of the lower leg (bisection of the tibia) and the bisection of the calcaneus drawn on the long leg calcaneal axial view. The longitudinal axis of the tibia falls within the midpoint of the talar body but medial to the bisection of the calcaneus by 5 to 10 mm.

The talocrural angle is drawn on the AP ankle radiograph defined by (A) a perpendicular to a tangent line to the tibiotalar joint and (B) the axis line of the malleoli.

The lateral distal tibial angle is drawn on the AP ankle radiograph, defined by the angle of (A) the tangent line to the tibiotalar joint and (B) the longitudinal axis line of the distal tibia.

The anterior distal tibial angle (ADTA) is drawn on the lateral ankle radiograph defined by (A) a tangent line to anterior and posterior margins of the tibiotalar joint and (B) the longitudinal axis line of the distal tibia. Note that the long axis of the tibia passes through the lateral talar process.