We’ve got an angle….. The Progression Angle
1st of a non sequential series
The progression angle is the angle to foot makes with the ground at initial contact of gait to loading response, and it is often carried through the gait cycle to toe off (see left image above). It is something we often look at to see how a patient may be compensating. It often represents how forces are traveling through the foot (see right image above).
The normal line of force through the foot during a gait cycle should begin at the lateral aspect of the heel, travel up the lateral column of the foot, across the metatarsal heads from the 5th to the 1st, and then through the hallux (see L part of right picture above.
We remember that the foot strikes the ground in a supinated posture, then pronates from initial contact through the middle of midstance (to provide shock absorption and initiate medial spin of the lower extremity: see picture bottom left); the foot should then supinate, to make the foot into a rigid lever, with this being initiated by the opposite limb going into swing and externally rotating the stance phase lower extremity (se picture bottom right)
The progression angle is determined by many factors, both anatomical and functional, and is often a blend of the 2.
Anatomical factors include:
- subtalar joint positioning
- tibial torsion
- femoral torsion
- acetabular dysplasia
and functional causes can include:
- compensation for a hallux limitus or rigidus
- weak glutes (of course we wouldn’t leave our favorite muscle out)
- loss of ankle rocker
- over or under pronation
- and the list goes on….
Next time we begin breaking this down into bite sized chunks to aid digestion.
Ivo and Shawn. Bald. Good Looking. Middle Aged. Definitive Foot and Gait Geeks : )