Posterior Leaf Spring AFO

An orthosis is an orthopedic device used to:

• support and align

• prevent or correct deformity

• substitute or enhance function

• decrease pain or discomfort

AFOs place the foot in optimal position for:

• weight acceptance at IC

• clearance in swing phase

• stability in stance phase

• optimize cadence/stride length

• limit excessive gait energy expenditure

PLS design

• low profile with trimlines posterior to malleoli

• substitutes for anterior compartment musculature

• decelerates foot slap

• facilitate swing phase clearance

• allows plantarflexion/dorsiflexion to a limited degree

• due to the posterior trimlines it offers limited ML stability

PLS indications

• drop foot deformity

• poor swing clearance

• mild coronal instability

• mild crouch gait

PLS contraindications

• moderate to severe crouch gait

• severe flexor or extensor tone

• calcaneal deformity

• ankle ML instability

PLS trimlines

• proximal: 1.5” distal to apex of fibular head (20 mm distal to fibular neck)

• anterior: terminates posterior to malleoli

• about 60% gastroc/soleus coverage

• toe plate 0.5” longer than longest toe for full plate

PLS additions

• ML post modification can effectively control varus/valgus deformity

• reinforcement - corrugation

tuning

• thickness of plastic

• width of plastic in posterior

• radius of plastic in posterior (flatter radius = truer spring)

PLS casting

sagittal plane alignment: 5° of DF

coronal/transverse plane alignment: neutral

forefoot neutral

PLS modifications

• junction of strut and foot plate

• symmetry

rehab for PLS

• consider safety and allowable motion

• carefully assess gait with orthosis - impact on rockers

• differentiate with carbon custom fit