Pes cavus Flashcards
These are pictures of the
left foot of a 20-year-old
man.
What do you see?
- These photographs show the anterior, medial and posterior views of a left foot
with a cavus deformity. - The hindfoot is in varus and there is elevated medial longitudinal arch.
- There doesn’t appear to be any significant clawing or abnormality of the toes.
(forefoot adduction) - Pes cavus can be divided in to :
Ø Pes cavus with hindfoot varus deformity
Ø Pes cavus with hindfoot calcaneus deformity (seen in polio or CMT due to weakness of GN)
What is the underlying pathology?
- Due to imbalance in the musculature of the foot. It can be caused by:
- plantar flexion deformity of the forefoot or
- dorsiflexion deformity of the hindfoot known as calcaneocavus.
-
The causes of a cavus foot may be broken down into:
Ø Congenital: idiopathic (most idiopathic cases are simple cavus without varus deformity)-
arthrogryposis-sequela of clubfoot
Ø Acquired: traumatic or neuromuscular.
The neuromuscular:
Ø Central disease: cerebral palsy or Friedrich’s ataxia, spinal cord lesions such as spina bifida or spinal
dysraphism,
Ø Peripheral lesions such as an HMSN or muscular causes such as muscular dystrophy.
what is the Pathoanatomy?
- It is resulted due to imbalance in the musculature of the foot.
- The primary deformity is forefoot plantar flexion specially of the 1st ray that may
result from weakness of tibialis anterior relative to peroneus longus, but more
commonly due to intrinsic weakness and contracture. It results in an increase in
arch height and pronation of forefoot(due to overpowered PL) -
Two factors contribute to the development of hindfoot varus deformity:
Ø The hindfoot assumes a compensatory varus posture to balance the forefoot valgus
Ø overpower of the tibialis posterior to the weakened peroneus brevis .
Ø Elevation of the arch occurs as a result of tightening of the windlass mechanism
due to imbalance between the weakened intrinsic and extrinsic muscles. - Clawing of the toes due to loss of the intrinsic function (MTP flexion and IP
extension) and the patient try to compensate by using the toe extensors resulting in
MTPJ hyperextension and IPJ flexion. - EHL acts as an accessory dorsiflexor in the absence of tibialis anterior.
- Overtime the plantar fascia contracts and the hindfoot varus deformity becomes
more rigid
What is HMSN?
* Hereditary Motor Sensory Neuropathy is a chronic progressive peripheral
neuropathy
Ø HMSN I:also called myelinopathy CMT, the most common HMSN. Autosomal
dominant, peripheral myelin degeneration due to defect in PMP 22 in Chr17.
occurs in the 1st to 2nd decade
Ø HMSN II: also called neuropathy CMT, the myelin sheath is intact but there is
Wallerian axonal degeneration. Occurs in the 2nd generation. Autosomal dominant
Ø HMSN III: autosomal recessive, presents in infancy, characterized by peripheral
nerve demyelination with severely decreased motor nerve conduction
How would you assess this patient?
History
v History:
* Common complaints in cavus feet are pain, particularly forefoot pain, lateral foot
pain under the metatarsal heads(1st and 5th), or arch pain, instability of the ankle
with a history of frequent ankle sprains. They may also have problems with fitting
of footwear or alteration of gait.
* Laterality:
Ø Unilateral involvement suggests a focal diagnosis (spinal cord anomaly or nerve injury)
Ø Bilateral involvement and family history are common in CMT
* Congenital or acquired: when did you notice the deformity? Were you born with
it?
* Progression: is it getting worse?
* Any associated weakness or numbness? Is there any weakness in your hands? Any
problems with your back? Any problems with your bladder or bowel?
* How the symptoms affect the function (work – sport – walking)
* Any previous history of ulceration or infection?
* I would also ask about any past medical and surgical history, family history (runs
in families), and any previous surgical or non-surgical treatment the patient had
received.
* What are the patient (and parent) expectations? What do you expect from your
visit?
How would you assess this patient?
examination by look
v Examination:
* My assessment would have two components. I need to determine any underlying cause of
the cavus and also evaluate the deformity itself.
* Look:
Ø whether this is a unilateral or bilateral deformity
Ø wasting of leg and hands muscles
Ø Inverted champagne bottle appearance
Ø Hindfoot in varus, neutral or valgus alignment. Is it in equinus or calcaneus ?
Ø height of the longitudinal arch and whether I can pass more than two fingers underneath.
Ø While the patient is standing I will look at the spine for any stigmata of an underlying
abnormality such as a hairy patch or scoliosis.
Ø Gait: The patient may have foot drop gait
Ø While the patient is standing I would perform Coleman block test to look for flexibility of
the hindfoot deformity by eliminating the deforming drive of the forefoot.
Ø In a cavus foot the first ray is plantarflexed so to place the foot stable on the ground the
hindfoot has to move into varus.
Ø In the Coleman block test the foot is positioned so that the lateral border of the foot and
the heel are placed on a block and the medial forefoot is allowed to hang off the edge of
the block. If the heel then assumes a physiological alignment of neutral to 5 valgus when
viewed from behind the hindfoot deformity is both flexible and driven by the forefoot.
Ø With the patient sitting I would inspect the soles of the feet for callosities or
ulceration
Ø I would like to inspect the patients shoes to evaluate for any lateral side shoe wear
especially in presence of hindfoot varus
How would you assess this patient?
examination by feel move and special test
Feel:
Ø Any areas of tenderness (forefoot-lateral foot)
Move:
Ø Look at the active and passive range of movement and see whether the deformities are
flexible or fixed.
Ø Tightness of tendoachilles (silverskoild test)
Neurological assessment
Ø I would assess sensation, deep tendon reflexes and power of the major muscle groups,
particularly the tibialis anterior and posterior and the peroneal tendons
Special test
Ø I would assess lateral ankle ligament competence with an anterior drawer
How would you assess this patient?
Investigations
Ø weight bearing radiographs, LAT ankle, and an AP and LAT of the foot.
Ø Talo-calcaneal angle (Turco) in lateral view, <35°
Ø Meary’s angle, the angle between the long axis of the talus and the first
metatarsal shaft. It will be increased with apex up.
Ø Hibb’s angle is the angle between the long axis of the first metatarsal shaft and
the long axis of the calcaneum. normally is 150 degrees but may decreases as the
cavus worsens
Ø The calcaneal pitch angle, the angle between the floor and the undersurface of
the calcaneum, should be less than 30 but may be increased in a cavus foot
Ø MRI of the spine is indicated if the patient had any signs or history suggesting an
underlying spinal cause (hairy patch or scoliosis- unilateral involvement)
What are the principles of management?
The goal of treatment:
pain relief – preserve function –protect the foot & ankle
from further deformity
What are the principles of management?
Non-operative treatment
Ø Non-operative treatment indicated in flexible mild cases
ü Physiotherapy: eversion & dorsiflexion strengthening -Heel cord stretching exercisesproprioception
exercise for instability
ü Orthotic: semi-rigid insole with depression for the 1st ray- heel lift & lateral wedge
What are the principles of management?
Operative treatment
Operative treatment
Ø Flexible: (hindfoot corrects in Coleman block test)
ü Plantar fascia release
ü PTT transfer to the dorsum of the foot through the interosseous membrane ( to decrease the varus
moment.
ü +/- transfer of peroneus longus tendon to peroneus brevis.
ü +/- TAL
ü +/- dorsiflexion osteotomy of the 1st MT
ü +/- Girdlstone-Taylor procedure (transfer of FDL to EDL) in flexible claw lesser toes
ü +/- Jones transfer (EHL transfer to the 1st MT neck + IP joint arthrodesis) in flexible Hallux
clawing
Ø Rigid: (hindfoot doesn’t correct in Coleman block test)
ü Add lateralizing calcaneal osteotomy
Ø Sever rigid deformities:
ü Triple arthrodesis
