Pes Cavus

Front 1

Define Pes Cavus

Back 1

Pes Cavus is a condition in which the foot presents with an unusually high medial longitudinal arch, that does not reduce on weightbearing.

Front 2

Name the three main etiologies of pes cavus

Back 2

Pes cavus can be:
1) Congenital
2) Acquired
3) Neuromuscular

Front 3

What are the six main characteristics of a pes cavus foot?

Back 3

Pes cavus characteristics:
1) rigid foot
2) digital contractures
3) varus heel
4) altered angle of inclication of foot bones
5) apropulsive gait
6) lateral weight distribution

Front 4

Name some functional deformities associated with pes cavus.

Back 4

1) rigid PF first ray
2) rigid forefoot valgus
3) uncompensated FF varus
4) limb length discrepancy
5) pseudo ankle equinus

Front 5

Why would neuromuscular dysfunction cause pes cavus foot?

Back 5

- causes changes in muscle tone and spasm
- causes muscular imbalance

Front 6

What determines the pathomechanics of pes cavus?

Back 6

There is no single set of common factors.
Underlying disease determines pathomechanics.

Front 7

What are the two classifications of pes cavus, and say how they differ?

Back 7

Pes cavus can be either:
a) anterior pes cavus (PF of forefoot structures)
b) posterior pes cavus (PF of rearfoot structures)

Front 8

What name is given to pes cavus where the FF is PF relative to the RF?

Back 8

Anterior pes cavus

Front 9

Define posterior pes cavus

Back 9

posterior pes cavus describes a foot in which the rearfoot if PF relative to the forefoot

Front 10

State the four types of anterior pes cavus, and explain how they differ?

Back 10

Anterior pes cavus:
1) Metatarsus cavus (PF at the Lisfranc joint)
2) Lesser tarsus cavus (PF at lesser tarsals)
3) Forefoot cavus (PF at Chopart's joint)
4) Combined anterior cavus (two or more of the above)

Front 11

What is posterior pes cavus?

Back 11

Posterior pes cavus is excessive dorsiflexion of the rearfoot in relation to the forefoot

Front 12

What is posterior pes cavus?

Back 12

In posterior pes cavus the calcaneus is dorsiflexed in relation to the talus

Front 13

What can pes cavus be an early sign of?

Back 13

may be an early sign of neuromuscular disease

Front 14

What kind of examination is indicated particularly for patients who have cavus feet, and why?

Back 14

You should do a thorough neurological examination, because there is a high correlation between pes cavus and neuromuscular disease.

Front 15

What congenital conditions are associated with pes cavus?

Back 15

Congenital conditions associated with pes cavus:
- Charcot Marie-Tooth
- cerebral palsy
- congenital clubfoot

Front 16

What acquired conditions are associated with pes cavus?

Back 16

- Trauma
- Polio
- Spinal cord tumours

Front 17

In what plane does pes cavus occur?

Back 17

Pes cavus is a sagittal plane deformity

Front 18

True or False?

Pes cavus can manifest itself in all three cardinal planes.

Back 18

True.

Although the sagittal plane component of deformity dominates, deformities in the other planes also occur.

Front 19

How could you differentiate between the different levels of anterior pes cavus in examination?

Back 19

Joint manipulation and observation of the location of dorsal prominences.

Front 20

What are the compensations for pure sagittal plane anterior pes cavus?

Back 20

1) ankle joint dorsiflexion
2) digital retraction
3) forefoot reduction of anterior pes cavus
4) buckling of MTPJs

Front 21

In pes cavus, why do we see digital retraction?

Back 21

Active pull of long extensors (extensor substitution for weak TibAnt)
Passive pull of long extensors on proximal digits causes hammering/clawing.
Weak intrinsics can't exert plantarflexion force.

Front 22

Why do the met heads plantarflex in pes cavus?

Back 22

DF force on phalanges from extensors. Met heads PF.

Front 23

What compensation is possible for a rigid pes cavus?

Back 23

Ankle must dorsiflex, because no DF available from forefoot.

Front 24

What is pseudo equinus?
Why might a patient with pes cavus develop pseudo equinus?

Back 24

Pseudo equinus is a functional limitation of ankle DF.
In rigid pes cavus the ankle must DF to enable heel to make ground contact. Insufficient DF remains for normal gait.

Front 25

What is pseudo equinus?

Back 25

A functional limitation of ankle dorsiflexion.

Front 26

Where will a patient with pes cavus generally get callus?

Back 26

Pes cavus callus sites:
1) Plantar met heads
2) Dorsum of retracted toes
3) Base of 5th met
4) Plantar heel

...but depends on whether rigid or flexible...

Front 27

What is extensor substitution and when does it occur?

Back 27

Occurs in swing phase and heel contact.
TibAnt weak so long extensors control dorsiflexion.
Weak intrinsics so extensors dominate and hyperextend MTPJs, causing digital retraction.

Front 28

Describe how the process of lesser toe deformity occurs

Back 28

-

Front 29

What gait disturbance would you see in pes cavus?

Back 29

- early heel lift
- lack of pronation through gait
- lack of shock attenuation
- rearfoot varus at heelstrike
- lateral ankle stability
- PF first ray

Front 30

What muscles are commonly involved in muscle imbalance in pes cavus?

Back 30

TibAnt weak - P.Longus strong (first ray held in valgus PF)
TibPost strong - P.Brevis weak (rearfoot held in varus, FF adducts)

Front 31

Secondary pathologies in pes cavus?

Back 31

- contracture of plantar fascia
- shortened Achilles tendon (medial pull on calcaneus)
- lateral ankle instability

Front 32

Conditions that cause pes cavus neuromuscular dysfunction?

Back 32

- cerebral palsy
- spina bifida
- Charcot Marie Tooth disease
- muscular dystrophy

Front 33

Congenital conditions causing pes cavus?

Back 33

- talipes equinovarus (clubfoot)
- Charcot Marie Tooth disease

Front 34

What test might you use to distinguish between rigid and flexible anterior pes cavus?

Back 34

Coleman block test (if rearfoot varus corrects this means PC is flexible)

Front 35

What is the differrence between rigid and flexible anterior pes cavus?

Back 35

Rigid APC - there is no frontal plane movement available to compensate.
Flexible APC - there is available movement, so deformity can reduce.

Front 36

What adaptive changes does the foot make in flexible APC?

Back 36

- constant adaptation between WB and NWB
- flexible forefoot valgus
- XS forefoot pronation

Front 37

What might the long term consequences be of flexible forefoot pes cavus?

Back 37

- Haglund's deformity from XS rearfoot motion
- degenerative changes to tarsals
- flexible may become rigid over time

Front 38

Where is the PF occurring in lesser tarsal anterior pes cavus?

Back 38

Intermediate and lateral cuneiforms.

Front 39

What is the name of the joint at which forefoot pes cavus occurs?

Back 39

Chopart's joint (aka MTJ)

Front 40

Where is the Lisfranc joint?

Back 40

tarso-metatarsal joints 1-5