Rearfoot Varus and Valgus Flashcards
What is the definition of rearfoot varus?
A fixed osseous structural abnormality in which the calcaneus is inverted when the STJ is in neutral and the MTJ is locked.
What is the aetiology of rear foot varus?
Five possible:
- distal tibial epiphyseal varus
- talar varum
- calcaneal varus torsion
- tibial varum
- Clinically indistinguishable
Describe distal tibial epiphyseal varus.
Aetiology of rear foot varus.
Inequality of growth between medial and lateral sides of the distal tibial epiphysis. Origin thought to be due to growth disturbance rather than congenital.
Describe talar varum.
Aetiology of rear foot varus.
Medial aspect of talus narrower than lateral aspect, tilting the calcaneus into varus.
Describe calcaneal varus torsion.
Aetiology of rear foot varus.
Frontal plane torque of the calcaneus, resulting in a ‘C’ shaped calcaneus.
How does the body compensate for rear foot varus?
The body attempts to bring the calcaneus back to 0 degrees (neutral), as described in the normal stance criteria. It can fully compensate or partially compensate.
What is the difference between a fully compensated rear foot varus and a partially compensated rear foot varus?
In a fully compensated rearfoot varus there is enough STJ pronation to allow the calcaneus to return to the neutral position.
In a partially compensate rear foot varus there is not enough STJ pronation to allow the calcaneus to return to neutral position.
Describe the gait abnormalities caused by rear foot varus.
- abnormal excessive pronation of the STJ and the oblique axis on heel strike, continuing until the calcaneus is perpendicular to ground (causing mid foot collapse)
- internal leg rotation during loading
- slight resupination in mid stance but STJ still pronated during propulsion
What are the signs/symptoms of rear foot varus?
Acronym: 'I am whilted' I- A- Arch lowers on WBing M- Mild callus sub 2/3 W- Wear on lateral heel H- Haglund's I- Inadequate shock absorption L- Lateral instability T- Tailor's bunion E- D- Deceleration excessive
Why does mild callus occur sub 2nd/3rd MPJs in patients with rear foot varus?
If pronating to compensate for RFoot varus we are unlocking the foot and it becomes unstable. Therefore it is difficult to push off through hallux and we would push off through all toes, creating more pressure/weight through 2nd/3rd MPJs.
Why does lateral heel wear occur in patients with rear foot varus?
Due to hitting ground in varus position - increased pressure through area
Why does Haglund’s syndrome occur in patients with rear foot varus?
Rubbing on top of lateral calcaneus creates an exostosis
Why does inadequate shock absorption occur in patients with partial or uncompensated rear foot varus?
Pronation is necessary to absorb shock as we land, and in partial/uncompensated rear foot varus pronation is not available.
Why is there lateral instability in patients with rear foot varus?
Landing in inverted heel position can lead to lateral ankle sprains.
Why does a Tailor’s bunion or hammered 5th MPJ occur in patients with rear foot varus?
Landing on 5th at a time it is unstable causes the joint to disrupt. This disruption will lead to a hammer toe/tailor’s bunion.
Explain why patients with rear foot varus experience symptoms relating to increased torsion/excessive deceleration.
- As heel lands in inverted position, the peroneals attempt to pull heel into eversion to correct. This results in overworked peroneals (and lateral muscle pain)
- Too much rotation causes the peroneals work harder to eccentrically slow motion (of pronation)
What is the definition of rear foot valgus?
A structural abnormality where the calcaneus is everted when the STJ is in neutral and the MTJ is locked.
How do you compensate for rear foot valgus?
You can’t - once the rear foot is in a valgus position it can only move further into valgus. It can’t work against gravity.
Describe tibial varum
Possible aetiology of rear foot varus. It is a FP abnormality of the distal 1/3rd of the leg where it is inverted relative to the ground when the STJ is in neutral.
What are the possible causes of tibial varum?
- curvature of the whole tibia
- genu varum resulting in tibial varum
- curvature of the distal 1/3rd of tibia
- Blount’s disease (lateral slippage of prox tibial epiphysis)
- Osteoarthritis
- trauma e.g. poorly set #
What are the three groups that rear foot valgus is split into?
- 0-3 degrees (valgus had little effect)
- 4-10 degrees (STJ pronates to end ROM with pronation symptoms)
- > 10 degrees (talar head contacts ground, which is stable but only 0-3 degrees xs pronation)
