Video
Definition
- Foot with high arch that fails to flatten with weight bearing
- Deformity may be hindfoot, forefoot or both
Aetiology
- The origin is often obscure but general cause related to Muscle Imbalance
- Duchenne believed due to intrinsic imbalance
- Others believe extrinsic imbalance
- Probably combination of both
- 66% found to be due to neurological disease (Brewerton 1963)
- 33% seen to have Charcot-Marie-Tooth disease
- Myelodysplasia & Poliomyelitis next in order
Epidemiology
Anatomy
Most of the following relates to idiopathic pes cavus
- 1. Dropping of Forefoot
- First ray drops initially
- The forefoot is supinated
- Initially flexible but later rigid
- 2. Contracture of the Plantar Fascia
- Increases height of the longitudinal arch
- The fascia further shortens with forefoot pronation & heel varus
- 3. Varus of Heel
- As forefoot fixed in pronation then heel varus must occur to allow placement of metatarsals on ground
- Initially only with weight bearing but eventually fixed
- As the heel varus ↑ the TA worsens the varus due to medial displacement
- 4. Clawing of Toes
- Overactivity of the EDL
- Initially reduced when foot dorsiflexed
- Then fixed with MT head callosities & PIPJ callosities dorsally
P>Pathology
- Two main theories related to muscle imbalance
- 1. Weakness of Intrinsics
- 2. Overactivity of Extrinsics
- Acute contracture
- Develops rapidly in paralytic disease (ie Polio)
- Postural contracture
- Immobility & oedema
- Muscle Imbalance
- Variable imbalance
- » In poliomyelitis see weakness of posterior calf musculature with normal anterior leg
- Thus deformity with unopposed tibialis anterior function
- » Charcot-Marie-Tooth is opposite to polio with weak anterior compartment & normal posterior
- Forefoot equinus develops due to weakness of tibialis anterior & normal peroneus longus as the peroneus longus depresses the first metatarsal & not opposed with tib ant
- The peroneus brevis weak with normal tibialis posterior & hence varus of hind foot
- The Long toe extensors attempt to elevate the foot & hyperextend the MTPJ & long flexors tighten & pull the distal joints into flexion
- The hindfoot secondarily inverts to allow placement of the metatarsals evenly on floor
Cla>Classification
Idi>Idiopathic
- Most common type
- Develops after 3 years of age
- Males = Females
- Often associated with spina bifida occulta
Sec>Secondary
- Neuromuscular disease
- Head
- Cerebral palsy
- Friedreichs ataxia
- Spinocerebellar swgeneration
- Cord
- Charcot-Marie-Tooth disease type 2
- Spina bifida
- Poliomyelitis
- Syrinx
- Diastematomyelia
- Tethered cord
- Cauda equina tumour
- Nerve
- CMT type 1
- Neurolemmoma
- Nerve injury
- Myopathies
- Trauma
- Compartment Syndrome sequelae
- Direct trauma to foot (malunion of midfoot fracture)
- Plantar fibromatosis
- Talipes equinovarus – often previously treated ß don’t forget CTEV!
- Arthrogryposis
- Head
History<>History
lass="wp-block-list">Examinat>Examination
lass="wp-block-list">- Joint motion
- Muscle power – individually
- Neurological exam to exclude dysraphism
- Back for usual stigmata of dysraphism
- Sensation
- Hands
- First Degree
- Foot normal
- Deformity mainly when foot relaxed
- Easy correction of forefoot & hindfoot
- Second Degree
- Equinus & pronation of first ray irreducible
- Early contractures of the Plantar fascia & Clawing of Big toe
- Third Degree
- Other MT claw & become increasingly irreducible
- Heel varus not correctable
- No bony deformity on XR
- Some degree of passive reduction possible
- Fourth Degree
- Pronounced deformity with no passive correction
- Structural changes at apex of the foot at Medial Cuneiform
- Some midtarsal movement remains
- Fifth Degree
- Most extreme degree
- All components firmly fixed
- Midtarsal structural defects present
- Toes dislocated at MTPJ
- Severely disabled
Investigat>Investigations
ss="wp-block-heading">Xrays>Xraysss="wp-block-list">- Lateral
- Talus & calcaneum parallel
- Sinus tarsi clearly visible
- Increased Mearys Angle (Angle between long axis of first MT & Talus) – normally 0 but ↑ in pes cavus
- AP
- Talus & Calcaneum superimposed – due to heel varus
Differential Dia>Differential Diagnosis
-block-heading">Treatment >Treatment-block-list">- Correct the forefoot equinus & pronation
- Never idiopathic unless exhaustive search fails to find another cause
- Immature foot treated with soft tissue surgery only
- Goal to produce plantar grade stable foot
First Degree (fl>First Degree (flexible)
-block-list">Second Degree (1>Second Degree (1st ray fixed with claw, plantar fascia contracted)
-block-list">- Steindler Release
- Longitudinal incision along medial aspect of calcaneum
- Fascia released from calcaneal attachment
- Release of
- Abductor hallucis
- FDB
- Abductor digiti minimi
- Subperiosteal dissection
- Long plantar ligament released
- Foot forcibly corrected
- Jones Procedure
- Dorsolateral approach to Great Toe
- EHL divided 2cm from insertion into DP
- Toe straightened & distal tendon inserted into the PP
- Then incision proximally over MT
- The proximal EHL tendon passed through the MT distally (via drill hole)
- Sutured to itself with tension
- Arthrodesis of the IPJ performed
- Osteotomy of First Metatarsal
- Dorsal closing wedge osteotomy at base
- Fixed with pin or screw
- Tendon Transfers
- Usually in Tibialis anterior loss (ie Charcot-Marie-Tooth)
- Tib Post transfer
- Peroneus longus to brevis