Definition
Pure Cavus Deformity characterised by
- dorsiflexion of Calcaneus
- plantarflexion of Forefoot
Aetiology
Weakness of Tendoachilles
Usually neuromuscular
- Polio (Most common worldwide)
- Spina bifida
- CP (can be due to overcorrection of T Ach)
- Spinocerebellar Degen (Friedreich's Ataxia)
- CMT
- Spinal dysraphism
Compartment Syndrome Deep Posterior
Pathology
Imbalance of tendoachilles and dorsiflexors
- dorsiflexion of calcaneus
- moves insertions of T Achilles anterior
- further weakens the lever arm
Forefoot becomes flexed because of
- gravity
- action of muscles during gait
- result is elevated longitudinal arch
History
Difficulty walking
Obvious deformity
Shoe fitting & wear problems
Painful callosities
Examination
Elevated longitudinal arch
Prominent heel with abundant callus on plantar aspect
- called pistol grip deformity
Heel usually in neutral
Usually claw toes
Xray
Lateral xray
- calcaneal pitch > 30o
- Meary's angle > 30o
MRI
Exclude dysraphism
Management
Non-operative
Modification of shoe wear & orthoses required
- cannot control deformity alone
- doesn't work
Operative
Age 0 - 5
Best avoided
Tendon transfer
- T Ant to T Achilles
Age 5-12
Grice arthrodesis STJ
- extra-articular
- stabilise STJ
Transfer muscles
- must be > Grade 5 power
Options
- Tibialis anterior
- Tibialis posterior
- peroneals
Age >12
As Above
Triple arthrodesis