Orthotic Modifications

Orthotics and their modifications

Modification Method

Modified Root – Standard orthotic device - forefoot balanced with a natural arch in line with corrected rearfoot. Posted at NCSP. Mid-foot control

A Medial Skive (Kirby) – Increased supinatory movement around STJ axis to control excessive pronation. Shaving plaster off the medial plantar surface of the heel section of the positive mold. This in effect adds extra medial intrinsic wedging to the device. Shells are ground at varying depths from 2 - 8 mm. A higher than normal heel cup is advised. Must take into account heel width thin heels pads don’t tolerate large amounts of skive. Rear-foot control

Indicated for pts who need additional pronatory control, difficulty resupinating the foot, paed flexible flat foot, post tib dysfunction, lower limb pathology caused by excessive stj pronation.

Contraindicated in pts with lateral heel pain- may increase pain due to shape of skive, lateral ankle instability and thin heel pad.

The Inverted Technique (Blake) is balanced as per modified root devices but to a far greater degree of inversion (starting at 15 degrees). A 1-5 ratio is generally used to prescribe these devices i.e. for every degree of correction required you should request 5 degrees of inversion. Recent studies suggest that the ratio is closer to 1-3. Majority of control at medial calcaneus, with minimal arch control. Rear-foot control

Provides increased force on medial side of plantar heel to resist pronation occurring.

Indicated for lig laxity, internal femoral torsion, pt that requires extra pronatory resistance, tib post rupture, ankle equines, runners with RF pronation.

Contraindicated in excessive inversion problems, lateral ankle sprains, ankle spurs, painful tailors bunion, poor shock absorption (rigid foot type), genu recurvatum.

Additions- plantarfascial groove, increase lateral heel cup, fat pad splays, extrinsic RF post. Good for sporty pts , increases shock absorption.

RCSP + NCSP= X

X x 5= posting

Eg RCSP = 3eve NCSP= 4inv

3eve + 4inv= 7 degrees

7 x 5 = 35 degree inverted posting

Cast Modifications

Extra control in mid-arch for over weight people or for significant hypermobility. Talo-navicular area for extra control of RF pronation in mod root devices.

A Cuboid Notch can help to lock the foot into the device and stabilizing the heel therefore limiting lateral foot movement.

Extra heel expansion- wider heel cup for pts with extra splay

minimal heel expansion- narrow heel cup for pts with narrow heel. Stops heel rolling around.

No lateral heel cup removes all of lateral side of heel cup without narrowing heel width.

A plantar fascia groove can be added to ease pressure on the plantar fascia. (Mark on cast to ensure groove is located in correct position).

Extra plaster first ray allows first ray to plantar flex and windlass mechanism to occur. Use with functional hallux limitus when movement resulted in pain.

Shell Type

4.5 mm Polypropylene is our standard plate thickness. 3mm or 6mm is available if required.

Superform carbon fibre composite is stronger & less brittle than other carbon composite materials.

EVA devices are manufactured in various densities

For a softer device choose a 3mm poly prop with an EVA fill

Shell Accommodations

A Mortons Extension extends the shell underneath the 1st MTPJ to limit movement of the 1st Metatarsal (eg hallux rigidus) or support a shortened first ray. Need to know how to measure how long

Apertured heels can be added in varying sizes. PPT fill is added to any apertures. Used for heel spurs, fat pad atrophy, nerve entrapment. Hole under heel. Can be filled in (Kelly calls it a heel seat)

A First Ray Cutout removes material just proximal to the 1st MTPJ to aid first ray plantarflexion. If shoe fit is a concern a Low bulk grind should be prescribed. Used for a rigid plantarflexed 1st ray or hallux limitus to initiate windlass mechanism

Low bulk grind- make device streamlined to fit in shoe.

Cobra