Unit 4: Foot Orthotics Flashcards
What are foot orthotics defined as
Inserts that are placed into a patient’s shoes, adaptions to a patient’s shoes and bespoke footwear
Applications of foot orthoses
Congenital abnormalities: club foot, pes cavus, planovalgus Diseases: polio Inflammatory conditions: RA Metabolic conditions: gout Degenerative conditions: OA Diabetes PVD
Describe club foot
Equinovarus. Unknown cause but associated with severe neurological conditions e.g. spina bifida
What are the 2 forms of club foot
Mild and severe
Mild: postural, can be corrected by manipulation, associated with breech birth
Severe: fixed, requires surgery to salvage foot function
What are pes cavus and planovalgus
Arched foot and flat foot: can arise spontaneously or in association with neuro disorders (cerebral palsy)
What is poliomyelitis caused by
Viral infection of the anterior horn cells of the spinal cord. Usually water borne
Consequences of poliomyelitis
Foot deformities and foot length discrepancy
Sensation remains normal
Which joints does RA typically affect
Small joints of the hands and feet
Why does foot trauma tend to take longer to heal than hand trauma
Vascular supply is not as good
Causes of gout
Abnormal purine metabolism leading to high uric acid levels e.g. due to treatment with antimetabolite drugs in cancer patients
Why does diabetes mellitus lead to foot trauma
Ineffective insulin control leads to peripheral neuropathy. Causes insensitivity and disrupted microvascular function
What 2 things is PVD commonly associated with
Diet and smoking
What are the 3 types of functional disorder
Deformity
Instability
Insensitivity
What are the objectives of orthotic treatment of irreducible deformity
Accommodate the deformity to obtain acceptable distribution of the weight-bearing forces
Compensate for loss of ankle/foot joint motion
What problems can irreducible deformity cause
Abnormal initial contact with the ground
Abnormal plantar pressure distribution
Abnormal, generally restricted, movements of the ankle and joints during dynamic activities
How is abnormal contact with the ground corrected
‘Fill-in’ the space between the foot and ground created by the deformity
How are abnormal plantar pressure distributions treated
Moulding the orthosis accurately to the foot shape, taking into account pressure sensitive and pressure tolerant tissue areas
How should abnormal ankle joint movement be compensated for
Designing an orthosis which deforms in a controlled manner to simulate normal joint movement
What are the objectives of treating instability with an orthosis
Prevent abnormal joint movements resulting from the instability
Compensate for any loss of ankle or foot joint function
How is normal initial foot contact re-established
Position and hold the ankle in normal plantigrade alignment
How is abnormal plantar pressure treated
Use an orthosis that resists collapsing of the foot
What factors contribute to tissue breakdown
Direct tissue pressure
Shear stress
Rate and duration of tissue loading
How to reduce direct pressure
Use a moulded interface
How to minimise shear stress
Reduce MTP extension between heel-off and toe-off by stiffening the support surface. Should also incorporate a heel cushion and rocker modification
Problems caused by fixed equinus foot deformity
Initial ground contact with the forefoot
Excessive pressure on the forefoot because of reduced area of support
Loss of normal ankle joint function
Elements of a foot orthosis designed to treat foot equinus
Built-up heel: simulates plantigrade ankle position
Moulded insole: redistributes pressure
Cushion heel: simulates plantarflexion at heel contact
Rocker sole: compensates for loss of dorsiflexion, assists roll-over prior to toe off
Problems associated with fixed varus deformity
Initial contact on the lateral aspect of the heel
Excessive pressure on the lateral aspect of the plantar surface
Loss of subtalar joint function
Elements of a foot orthosis designed to treat fixed varus
Medial sole
Built up heel
Moulded insole: shaped to redistribute pressure across the plantar surface
Problems caused by an unstable pronating foot
Foot collapses into valgus = excessive pressure on medial aspect of foot
Absent subtalar supination/pronation = less functional gait pattern
Elements of a foot orthosis designed to treat pronating foot (DIRECT methods)
Moulded arch support to hold the medial arch
AFO for severe cases: applies 3-point force system across the subtalar joint
Indirect methods of treating pronating foot
Wedge/float the heel of the shoe to promote supination at heel contact
Moulded heel cup
Problems caused by toe clawing
Excessive pressure under the metatarsal heads as the heel leaves the ground to initiate push off
Loss of final toe extension movement
Elements of a foot orthosis designed to treat toe clawing
Metatarsal support: applies corrective force for realignment
Stiffener in the sole of the orthosis: resists excessive dorsiflexion, reduces loss of push-off
What are the early indicators of high pressure areas
Corns and callousing
What methods are used to identify patients at risk of tissue breakdown due to high pressure areas
Barefoot assessment using pressure platforms
In-shoe pressure monitoring systems
How are high pressure areas treated
Adapted plaster of Paris cast
Extra-depth insole with associated boot/shoe
Describe the structure of the extra-depth insole
High density closed cell foam base
Intermediate medium density layer
Thin top cover of soft leather or neoprene
