Normal Axes/Angles of the Foot Flashcards
(20 cards)
Longitudinal Axis of the RF
Central posterior to anteromedial calcaneus
- Longitudinal bisection of the RF
- Stable reference point (static, doesn’t move)
Alternative: line parallel to lateral calcaneus
Longitudinal Axis of Talar neck and Head
Found by connecting midpoints of the talar neck and head.
- Should be an approximate longitudinal bisection of the 1st met in a rectus foot
- Good reference for foot linearity and stability
Longitudinal Axis of Metatarsus
Bisection of the second metatarsal
- Represents orientation of metatarsals and FF in the transverse plane
- *The 2nd met is the guide for the FF
Talocalcaneal Angle
Angle is formed by the longitudinal axis of the RF and the longitudinal axis of the talar neck and head
Normal: 15-18° (20-23° if you use the lateral border of the calcaneus)
How does a pronated foot affect the longitudinal axis of talar neck and head and the talocalcaneal angle?
Longitudinal axis of talar neck and head: points toward midline of body
Talocalcaneal angle: increased
How does a supinated foot affect the longitudinal axis of talar neck and head and the talocalcaneal angle?
Longitudinal axis of talar neck and head: points toward longitudinal axis of calcaneus
Talocalcaneal angle: decreased
Lesser Tarsus Angle
Angle between the longitudinal axis of the RF and the longitudinal axis of the lesser tarsus (MF axis)
- No real normal, but 10° (+/- 5°) is accepted
- Longitudinal axis of the lesser tarsus is a line perpendicular to the transection of the midfoot
Metatarsus Adductus Angle
Angle between longitudinal axis of lesser tarsus and longitudinal axis of metatarsus
- Normal is metatarsus adducted 10-20° to lesser tarsus
- Deformity: >20°
- Alternative: use bisection of intermediate cuneiform in place of longitudinal axis of lesser tarsus–> normal: 13-23°
Proximal Articular Set Angle (PASA)
Angle between a line perpendicular to the 1st met articular cartilage and the longitudinal axis of the first metatarsal
- Normal: 0-8° abducted to 1st longitudinal
Distal Articular Set Angle (DASA)
Angle between a perpendicular to the proximal articular cartilage of the 1st MPJ and the longitudinal axis of the proximal phalanx
- Normal: 7-9° abduction of phalanx shaft to cartilage
Hallux Abductus Angle
Angle between the longitudinal axis of the 1st met and the longitudinal axis of the proximal phalanx
- Normal: 0-15° abducted to 1st met
Metatarsus Primus Adductus Angle (IM Angle)
Angle between the longitudinal axes of the 1st and 2nd mets
- Normal: 8° adducted 1st to 2nd met
- Pathologic: >/=12° in a rectus foot, 10° in met adductus
Sesamoid position
Normal: position 1 (not touching the longitudinal axis of 1st met)
Position 4: tibial sesamoid centered on bisection
**At position 5, tibial sesamoid begins to cross over the longitudinal axis
Position 7: tibial sesamoid completely lateral to bisection
What angles are considered when evaluating a bunion?
PASA DASA HAV IM Sesamoid Position
Calcaneal Inclination Angle
Anterior plantar calcaneal tuberosity to plantar calcaneocuboid joint–> angle formed w/ ground
- Normal: 18-20°
How is the calcaneal inclination angle affected in pronation and supination?
Pronation: angle is decreased (<18-20°)
Supination: angle is increased (>18-20°)
Talar Declination Angle
Perpendicular to lined drawn between the superior articulation of talar head w/ navicular to anterior inferior articulation of talus and calcaneus–> angle formed w/ ground
- Normal is 21°
How is the talar declination angle affected with pronation and supination?
Pronation: increases the angle as talus drops toward the ground
Supination: decreases the angle as talus rises away from the ground
Cyma Line
Lazy S that runs between a well-aligned calcaneocuboid and talonavicular joint
How is the cyma line affected by pronation and supination?
Pronation: causes anterior break in cyma line as talus appears more anteriorly
Supinations: causes posterior break
