Forefoot Varus and Supinatus

Question 1

What is the definition of forefoot varus?

Answer 1

A structural abnormality where the forefoot is inverted relative to the rearfoot when the STJ is in neutral and the MTJ is locked.

Question 2

What is the definition of forefoot supinatus?

Answer 2

A fixed supinated position of the longitudinal axis of the MTJ. It is secondary to STJ pronation when the calcaneus is everted. It is a secondary positional deformity resulting from soft tissue adaptation.

Question 3

What is the aetiology of forefoot varus?

Answer 3

• Failure of the normal development of valgus torsion in the head and neck of the talus.
• PF cuboid resulting in PF 4th and 5th met (created FFV as 4th/5th are sitting lower than other mets)
• PF 5th met (same as above - FFV created by lower 5th)

Question 4

How do you differentiate between forefoot varus and forefoot supinatus?

Answer 4

Put foot into STJ neutral and lock the MTJ. If there is FFV present and you can feel a spongey resistance when you try to push it into eversion (of the LA of the MTJ), then there is forefoot supinatus present. Often forefoot supinatus is concomitant with forefoot varus.

Question 5

What are the pathomechanics of forefoot varus?

Answer 5

• forefoot is inverted at forefoot loading
• increased GRF lateral to the STJ axis
• STJ pronates until forefoot contacts or until STJ end ROM

Question 6

Do you compensate for the rearfoot or the forefoot first?

Answer 6

Rearfoot

Question 7

What abnormalities in gait does forefoot varus cause?

Answer 7

• super pronated foot throughout the whole gait cycle

- often flat, flexible feet that respond well to orthotics

Question 8

Why are patients with forefoot varus good candidates for tib post dysfunction?

Answer 8

Because they continuously pronate throughout the gait cycle and this overloads the tib post muscle (attempting to slow excessive pronation).

Question 9

What happens if the STJ pronates more than 3 degrees in order to compensate for forefoot varus?

Answer 9

The STJ will pronate to end ROM if more than 3 degrees of pronation is required to compensate for forefoot varus position.

Question 10

Does the STJ compensate first or the MTJ?

Answer 10

The STJ will compensate first and then the MTJ will contribute a further 5 degrees.

Question 11

What are the rules when calculating RCSP?

Answer 11

• STJ compensation first, followed by forefoot
• STJ will go to 0 degrees if possible (if inverted), if everted compensation cannot occur
• Forefoot compensation occurs via STJ first, then the MTJ
• If forefoot compensation >3 degrees, STJ goes to end ROM

Question 12

What symptoms are associated with a fully compensated forefoot varus?

Answer 12

• symptoms are caused by an unstable foot (due to abnormal pronation to correct varus)
• Callus (sub 2/3, medial 1)
• HAV
• Inflammation (neuroma)
• Postural fatigue
• Fasciitis (plantar)
• Lesser toe deformities
• Inflammation of tib post
• Patello-femoral syndrome
• Shin splints

Question 13

What symptoms are associated with an uncompensated forefoot varus?

Answer 13

• Callus sub 1 and 5 with IPJ symptoms/lateral shoe wear
• Lateral loading prolonged and excessive with late progression to IPJ of hallux
• Inverted position of forefoot
• Partial compensation will cause effects relating to how much comp occurs

Question 14

Explain how a fully compensated forefoot varus can cause shin splints.

Answer 14

The anterior compartment is overloaded as it tries to eccentrically slow pronation.

Question 15

Explain how a fully compensated forefoot varus can cause callus sub 2/3 and medial 1st.

Answer 15

• centre of gait moved medially, as the hallux cannot accept the weight due to unstable foot
• foot is unstable as pronation unlocks bones

Question 16

Explain how a fully compensated forefoot varus can cause HAV.

Answer 16

• unstable foot from pronation > can’t propel off hallux so roll of instead > and hallucis has mechanical advantage > HAV cascade

Question 17

Explain how a fully compensated forefoot varus can cause inflammation/neuroma.

Answer 17

• splayed/unstable foot causes the mets to squash the nerve

Question 18

Explain how a fully compensated forefoot varus can cause postural fatigue.

Answer 18

• we don’t have a stable base so our muscles overwork to keep us upright

Question 19

Explain how a fully compensated forefoot varus can cause plantar fasciitis.

Answer 19

• foot doesn’t lock as it is in pronated position > instead of propelling off rigid lever, propel off PF instead

Question 20

Explain how a fully compensated forefoot varus can cause lesser toe deformities.

Answer 20

• FDL doesn’t pull straight so transverse plane is interrupted

Question 21

Explain how a fully compensated forefoot varus can cause tibialis posterior inflammation/tendonitis.

Answer 21

• due to excessive pronation, tib post is constantly at end ROM > this causes tendon to be overworked, as it is harder for it to contract at end ROM

Question 22

Explain how a fully compensated forefoot varus can cause patella-femoral syndrome.

Answer 22

• knees medially rotate from pronation, disrupting the transverse plane and changing pressure areas etc

Question 23

Explain how an uncompensated forefoot varus can cause callus sub 1 and 5.

Answer 23

• not loading smoothly from 5th to 1st > ‘clunking’ heavily onto 5th then 1st
• poor shock absorption

Question 24

Explain how an uncompensated forefoot varus can cause prolonged and excessive lateral loading.

Answer 24

• due to inverted position of forefoot and little shock absorption

Question 25

Explain how an uncompensated forefoot varus can cause an inverted position of the forefoot.

Answer 25

• MTJ and STJ cannot compensate fully for the varus position of the forefoot