A cavus foot deformity refers to an abnormally elevated medial arch which is marked by a varus hindfoot, high calcaneal pitch, high-pitched midfoot and a plantar flexed-adducted forefoot.
Aminian et al. describe the biomechanics of a pes cavus foot as involving narrowing of the talo-calcaneal angle which causes the navicular to move to a superior position in relation to the cuboid, as opposed to medially; this makes it difficult for the Choparts joint to function efficiently.
With the foot locked in hindfoot inversion and forefoot varus throughout the stance phase, there is less distribution of stress across the feet which can result in conditions such as metatarsalgia, iliotibial band syndrome and plantar fasciitis.
Pes cavus is categorised as neuromuscular, congenital, idiopathic or traumatic; the idiopathic category is often classified separately from the congenital category.
According to Rosenbaum et al, the neuromuscular causes of pes cavus could involve any of the following – hereditary motor and sensory neuropathies, cerebral palsy, after effects of stroke and spinal cord lesions.
An underlying neurologic abnormality is reportedly found in at least two-thirds of adults with the condition; muscle imbalance typically exists in the form of strong peroneus longus and tibialis posterior muscles functioning alongside weak tibialis anterior and peroneous brevis muscles.
Although an idiopathic cavus foot (such as the subtle cavus deformity) does not have any underlying causes, it may be associated with ankle instability, varus ankle arthrosis, plantar fasciitis, metatarsalgia or claw toe deformity.
Traumatic causes of a pes cavus foot can include crash injuries, peroneal nerve damage, compartment syndrome and talar neck fracture malunion; the latter results in a fixed varus position of the subtalar, talonavicular and calcaneocuboid joints.
The efficacy of orthotic management in the treatment of a painful cavus foot deformity was demonstrated successfully by Najafi et al. by retrospectively re-analysing plantar pressure data at baseline and three months post custom-made foot orthotic intervention.
The findings of the study found that custom-made foot orthoses usage increased self-selected walking speeds, enhanced proprioception, reduced inter-cycle walking speed variability and caused a reduction in the centre-of-mass oscillation both medially and laterally.
MASS4D® customised foot orthotics offer maximum reduction in local peak pressures by providing proper support to the foot to facilitate healthy distribution of weight, to increase the contact area across the plantar surface of the foot, to reduce excessive supination and to promote healthy pronation.
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