POLIOMYELITIS- POLIOMYELITIS- DEFORMITIES OF DEFORMITIES OF THE FOOT &ANKLE AND THEIR THE FOOT &ANKLE AND THEIR

MANAGEMENTMANAGEMENT

• Acute anterior poliomyelitis is an infectious disease caused by a neurotropic virus which initially invades the GIT & respiratory tracts & subsequently spreads to the CNS.

POLIO VIRUS

• The disease usually passes through the following stages:

Acute stage

Stage of recovery or convalescence

Stage of residual paralysis

Clinical presentations to the Clinical presentations to the orthopaedician in the current orthopaedician in the current

contextcontext

• Patients usually in the stage of post polio residual paralysis present with various deformities

• Some may come asking for a change from long-standing braces & calipers

• Post polio syndrome

• Some with flail & unstable joints seeking upgrading in their ambulatory status

Pre operative considerationsPre operative considerations

• Selection of the correct procedure at the correct time

• Problem identification– Muscle imbalance– Joint deformity– Joint instability– Limb length discrepancy

Goals of treatmentGoals of treatment

• Preventing or correcting deformities

• Reestablishing muscle power

• Stabilising flail joints

• Eliminating the need for such external supports such as braces & corsets

Causes of skeletal deformityCauses of skeletal deformity

• Muscle imbalance

• Unrelieved muscle spasm

• Habitual faulty posture (aided sometimes by gravity)

• Dynamics of activity

• Growth

Stabilisation of relaxed or flail jointStabilisation of relaxed or flail joint

• Joint instability can be static or dynamic

• Stabilisation can be achieved

by partially or completely restriting ROM of the joint or

by eliminating an abnormal motion

Static instability can be stabilised indefinitely by

• Orthoses

• Tenodesis

• Fixation of ligaments or artificial ligaments

• BONY PROCEDURES- BONE BLOCKS OR ARTHRODESIS

• Dynamic instability is one in which there is muscle imbalance around the joint.

• Operations to correct a joint deformed as a result of muscle imbalance will not prevent recurrence of deformity unless the muscle imbalance is also corrected.(Sharrard)

• The most effective method of reestablishment of muscle power is tendon transfer

Tendon TransferTendon Transfer

• Shifting of a tendinous insertion from its normal attachment to another location so that its muscle may be substituted for a paralysed muscle in the region

Principles of tendon transferPrinciples of tendon transfer

• The muscle to be transferred must be strong enough to accomplish what the paralysed muscle did or to supplement the power of a partially paralysed muscle. A transferred muscle loses at least one grade in power after transfer.

• The freed end of the tendon should be attached close to the insertion of the paralysed tendon & should be routed in a direct line b/w its origin & new insertion

• The transferred tendon should be retained in its own sheath or of another tendon;it should be passed throgh tissues that will allow it to glide.

• The nerve & blood supply to the transferrecd muscle must not be impaired.

• The joint on which the muscle is to act must be in a satisfactory position.

• The transferred tendon must be securely attached to bone under tension slightly greater than normal.

• Agonists are preferred to antagonists.

• The tendon to be transferred should have, when possible, a range of excursion similar to the one it is replacing.

Non phasic transfers & Phasic Non phasic transfers & Phasic conversionconversion

• Often a non phasic muscle must be trained to assume the proper phase of the walking cycle after transfer.

• The mixing of swing phase & stance phase transfers should not be done.

• Phasic conversion is not related to the time from onset of the disease to transfer

• Bracing or splinting after surgery seems to have no effect on phasic conversion

Considerations in timing Considerations in timing proceduresprocedures

• AGE of the patient is most important

• Arthrodesis should be done near skelatal maturity

• Tendon transfer should be done in children only when they are old enough to cooperate in muscle reeducation

FOOT AND ANKLEFOOT AND ANKLE

• Since the foot & ankle are the most dependent parts of the body and are subjected to greater strain than other parts, they are especially susceptible to deformity from paralysis.

Basic anatomyBasic anatomy

Movements at the ankleMovements at the ankle

The aim of treatment of the paralysed foot in poliomyelitis is to obtain a foot which is plantigrade during stance,which can push off well at the initiation of swing, and which can dorsiflex actively during the swing phase.

A plantigrade footA plantigrade foot implies that there is no varus or valgus deformity with normal distribution of weight under the heel and metatarsal heads

• To achieve a powerful push off, there must be adequate power (grade 4/5 ) of plantarflexion

• A dorsiflexor power of at least grade 3 is required to achieve active dorsiflexion during swing

Deformities around the foot & ankleDeformities around the foot & ankle

Deformities of the foot may beSupple and passively correctable

orRigid and fixed

• Supple deformities can be very effectively corrected by performing a suitable muscle transfer.

• Rigid deformities require soft tissue release operations, tissue distraction with Ilizarov, osteotomies or resection of bone

Patterns of muscle paralysis & Patterns of muscle paralysis & resultant deformitiesresultant deformities

Tibialis anterior+ toe extensors

Equinus

Triceps surae Calcaneus

Tibialis posterior Planovalgus

Tib ant+ peronei Equnovarus

Tib ant+ tib post +toe extensors

Equinovalgus

Tib ant+ Tib post Valgus

Triceps surae+ tib post Calcaneovalgus

Triceps surae+ peronei Calcaneovarus

PEABODY CLASSIFICATIONPEABODY CLASSIFICATION

Limited extensor- invertor insufficiencyGross extensor-invertor insufficiency

Type A

Type BEvertor insufficiencyTriceps surae insufficiency

1)Paralysis of the tib ant; normal toe extensors-eqinus & cavus or planovalgus-usually requires only transfer of EHL to the base of first metatarsal

2)Type A- paralysis of tib ant+ toe extensors; normal tib post-equinus or equinovalgus-PL to dorsum of foot

Type B –paralysis of all 3 muscles-transfer of peronei

POLIO VIRUS

3)When slight, EHL is transferred to the base of fifth metatarsal

When gross, tib ant to cuboid & EHL to first metatarsal

4)Calcaneovalgus-peronei are transferred to the calcaneum

Calcaneovarus-tib post + FHL are transferred

Calcaneocavus-peronei+tib post to calcaneus

• Tendon transfers around the foot & ankle after the age of 10/11 are usually supplemented by stabilisation procedures to

1)Spare a tendon for transfer 2)To correct fixed deformities 3)To establish enough lateral stability for

weight bearing 4)To compensate for the loss of power in

the invertor and evertor muscles

• When tendon transfer and bone stabilisation are contemplated in the same patient, THE LATTER IS DONE FIRST.

STABILISATION OF THE JOINTS STABILISATION OF THE JOINTS OF FOOT AND ANKLEOF FOOT AND ANKLE

Triple arthrodesis; it is the surgical fusion of talo-calcaneal, talo-navicular& calcaneo-cuboid joints

• Whitman layed down the principles of arthrodesis on a sound basis

• Concept of posterior displacement of the foot : transfers its fulcrum (the ankle) anteriorly to a position near its centre & lenghtens its posterior lever arm;this is of particular advantage when the triceps surae is weak

• He advised talectomy for the same

HOKE in 1921 and DUNN in 1922 suggested removing HOKE in 1921 and DUNN in 1922 suggested removing bone from b/w the cuneiform & talus to produce posterior bone from b/w the cuneiform & talus to produce posterior

displacementdisplacement

• 1n 1923 RYERSON advised inclusion of calcaneocuboid joint to the other two joints for added stability

The two important modifications of triple fusion are the The two important modifications of triple fusion are the LAMBRINUDI technique & the ELMSLIE techniqueLAMBRINUDI technique & the ELMSLIE technique

• Lambrinudi- for equinus deformity. Here an anteriorly based wedge is resected from the talus & calcaneum while the foot is held fully plantarflexed.

• Elmslie Cholmeley-for calcaneus deformity. Here a posteriorly based wedge is resected while the foot is held in full dorsiflexion

LAMBRINUDI ARTHRODESISLAMBRINUDI ARTHRODESIS

Sub talar arthrodesisSub talar arthrodesis

Subtalar arthrodesisSubtalar arthrodesis

• Only arthrodesis permissible in the skeletally immature foot (b/w 3-8 years)

• Green & Grice developed an extra articular subtalar fusion by packing the sinus tarsi with cortical tibial grafts fashioned so as to prise open the sinus tarsi

ModificationsModifications

• A fibular strut graft is passed in the axis of the subtalar joint from the neck of the talus across the sinus tarsi into the calcaneum (Brown & Batchelor 1968)

• A screw is placed the sinus tarsi in the axis of the subtalar joint and the sinus tarsi is packed with cancellous graft (Dennyson and Fulford 1976)

Green & Grice extraarticular Green & Grice extraarticular subtalar arthrodesissubtalar arthrodesis

Dennyson Fulford arthrodesisDennyson Fulford arthrodesis

Pantalar arthrodesis Pantalar arthrodesis

• This operation is indicated as follows• For patients who have calcaneus or equinus

deformities combined with lateral instability of the foot.

• For patients whose deformity has recurred after a bone block or a Lambrinudi procedure

• Some times for patients with an unstable knee from paralysis of the quadriceps muscle

Orthotic stabilisationOrthotic stabilisation

• Ankle foot orthoses are the mainstay• AFOs are modified to control various instabilities

of the foot & ankle in poliomyelitis

ModificationsModifications

Instability Upright T-strap Joint

Equinus Double irons - 90 degree foot drop stop or toe raising spring

Varus Medial iron Lateral Free motion joint

Valgus Lateral iron Medial Free motion joint

Calcaneus Double iron - Reverse foot drop stop

Flail foot Double iron - Limited motion joint

Common deformities in Common deformities in poliomyelitispoliomyelitis

• CLAW TOES• CAVUS DEFORMITY & CLAW FOOT• DORSAL BUNION• TALIPES EQUINUS• TALIPES EQUINOVARUS• TALIPES CAVOVARUS• TALIPES EQUINOVALGUS• TALIPES CALCANEUS

CLAW TOESCLAW TOES

Occur in 2 situations• When long toe

extensors are used to substitute weakened ankle dorsiflexors

• When long toe flexors substitute weakened triceps surae

The responsible mechanism can be The responsible mechanism can be identified by careful analysis of the footidentified by careful analysis of the foot

• In the first case during the swing phase toe extensors actively contract producing the deformity.During stance phase it disappears

• In the second case,clawing of the toes occurs only when propulsion or push off is attempted

• When claw toes are associated with cavus, the latter should be corrected first, since clawing will then usually correct spontaneously

Treatment of clawing of the great Treatment of clawing of the great toetoe

• Modified Jones operation: EHL is attached to the neck of first metatarsal;interphalangeal joint is arthrodesed

Clawing of lateral toesClawing of lateral toes

• The long toe flexors are divided at their insertion & attached to theplantar aspect of theproximal phalanx. Clawing is corrected by interphalangeal capsulotomies

CAVUS DEFORMITY & CLAW CAVUS DEFORMITY & CLAW FOOTFOOT

• Deformity caused by a poorly understood weakness or imbalance of intrinsic or extrinsic muscle groups of the foot, or both.

• The primary deformity is a drop or equinus of the forefoot

• Secondary deformity is clawing of the toes

• In severe cavus all the plantar structures contract

Treatment of mild cavusTreatment of mild cavus

• Conservative measures:metatarsal bar on the shoe or an insole with a metatarsal pad

• Several operations have been recommended, each based on a theory of muscle imbalance

• Bentzon-the cause is an imbalance b/w tib ant & PL. So he recommends division of PL& imbrication of its proximal stump into PB

• Garceau & Brahms-imbalance of abductor hallucis, flexor hallucis brevis, flexor digitorum brevis & quadratus plantae. They described selective denervation of these muscles

Treatment of severe cavusTreatment of severe cavus

• Steindler plantar fasciotomy

• Dwyer osteotomy of calcaneus

• Cole anterior tarsal wedge osteotomy

• Japas V osteotomy

• Tendon transfers-Jones operation for the great toe & Hibbs operation for clawing of the lateral toes

Steindler stripping operationSteindler stripping operation

• Along a short medial approach, the long plantar ligament & origins of the short plantar muscles are subperiosteally stripped

Dwyer osteotomyDwyer osteotomy

• Wedge of bone with its base lateral is resected inferior & posterior to the PL & parallel to it. Medial borer of the calcaneus is not divided, but broken manually to close the gap

• Dwyer’s is done when there is a cavovarus• Dwyer contends that rendering the varus

foot plantigrade by the above operation, weight bearing exerts a corrective influence in progressive decrease of the deformity

• More effective before structural deformity develops & before skeletal maturity

Cole anterior tarsal wedge Cole anterior tarsal wedge osteotomyosteotomy

Japas V osteotomyJapas V osteotomy

• Advantages- no bone is excised; no shortening

• Lenghtening of the plantar surface of the foot along with better deformity correction

• Recommended for children 6 years or older

DORSAL BUNIONDORSAL BUNION

• In this deformity the shaft of the first metatarsal is dorsiflexed & the great toe is plantar flexed

Two types of muscle imbalance may cause Two types of muscle imbalance may cause a dorsal buniona dorsal bunion

• M.c. is b/w Tib ant & PL.

Normally tib ant raises the base of the first metatarsal;the PL opposes this action

When the PL is weak, first metatarsal is dorsiflexed by the unopposed tib ant &the great toe plantar flexes to establish a point of weight bearing

Many bunions develop after ill advisedtransfer of the PL

• The second & less common mechanism is a paralysis of all muscle groups except triceps surae & long toe flexors

• This causes the great toe to be constantly flexed to sustain push off

• The first metatarsal head is then displaced upward to accomodate

LAPIDUS operation to correct dorsal LAPIDUS operation to correct dorsal bunionbunion

Shaded areas show the

fused joints

FHL has been converted to depressor & dorsiflexor action of tib ant is abolished by transferring it posteriorly

TALIPES EQUINUSTALIPES EQUINUS

• Causes

1)Muscle imbalance-plantar flexors are stronger than the dorsiflexors

2)A flail foot under the influence of gravity develop tendo calcaneus & posterior capsular contracture

TreatmentTreatment

• When not responding to conservative measures, tendo Achilles lenghtening is indicated.

• After correction has been obtained, one of the following stabilising operations should be done to prevent recurrence

• Posterior bone block

• Lambrinudi procedure

• Pantalar arthrodesis

• Arthrodesis of the ankle joint

Techniques of TA lenghtening[Techniques of TA lenghtening[

• Whites’ percutaneous TA lenghtening-based on the observation that the tendon rotates about 90 degrees b/w its origin & insertion; the rotation is from medial to lateral

• Hauser developed a similar method based on the observation that the rotation begins about 12-15 cm proximal to the insertion

• Z- plastic tenotomy of TA & posterior capsulotomy

Either in the lateral or AP plane.Lateral plane is preferred because the width of the tendon is maintained

In equinovarus deformity, lenghtening in AP plane that leaves the lateral half attached to the calcaneum is preferred to prevent hindfoot varus

A word of caution-Do not correct A word of caution-Do not correct equinus in an ambulant patient with equinus in an ambulant patient with

quadriceps paralysisquadriceps paralysis

Campbell posterior bone blockCampbell posterior bone block

• Here a bone block is constructed on the posterior aspect of talus & superior aspect of calcaneum in such a manner that it will impinge on the posterior lip of the distal tibia & prevent plantar flexion of the ankle

• The operation has been modified by Gill, Inclan and others

• It is usually combined with a triple arthrodesis

• Fibrous or bony ankylosis of the ankle must be guarded against.

TALIPES EQUINOVARUSTALIPES EQUINOVARUS

• Is characterised by equinus deformity at the ankle, inversion at the heel, adducton at the midtarsal joints & supination of the forefoot

• When the deformity is of long standing duration, a cavus deformity of the foot develops; clawing of the toes may develop secondarily

PathogenesisPathogenesis

• The peroneal muscles are paralysed or severely weakened

• The tibialis posterior is usually normal

• The tibialis anterior may be weakened or it may be normal

• The triceps surae is comparatively strong & gets contracted

• The equinus position thus produced increases the mechanical advantage of the tib post; this in turn encourages hind foot inversion & forefoot adduction and supination

Treatment of talipes equinovarusTreatment of talipes equinovarus

Depends on Age of the patientForces causing deformitySeverity of the deformityIts rate of increase

Treatment in a skeletally immature Treatment in a skeletally immature footfoot

• A brace may help to prevent deformity

• If deformity increases, wedging cast technique is employed

• Rarely Steindlers operation,TA lenghtening & posterior capsulotomy may be necessary

• Once the deformity has been corrected, surgery is indicated to prevent recurrence

• The tibialis posterior is usually the main deforming force, & unless its influence is removed, the deformity will recur

• Barr & Blount procedure- Transfer of the tib post anteriorly through the interrosseous membrane to the anterolateral tarsal area is the most effective procedure

Ober modification- rerouting the Ober modification- rerouting the tendon subcutaneouslytendon subcutaneously

Split tibialis anterior transferSplit tibialis anterior transfer

• Hoffer described this technique when the tib post is weak & tib ant is strong enough

Treatment in a skeletally mature Treatment in a skeletally mature footfoot

• Foot is stabilised by a triple arthrodesis & cavus is corrected at the same sitting by Steindlers release

• 4-6 weeks later TA is lenghtened combined with a modified Jones operation & a Barr transfer

• External tibial torsion is corrected by derotational osteotomies of tibia & fibula

TALIPES CAVOVARUSTALIPES CAVOVARUS

TALIPES EQUINOVALGUSTALIPES EQUINOVALGUS

• Usually develops when The tib ant & tib post are weak The peronei are weak The triceps surae is strong & contracted• Triceps surae pulls the foot into equinus• Peronei pull into valgus• The weight bearing thrust shifts to the

medial border of the foot

Treatment in a skeletally immature Treatment in a skeletally immature footfoot

• A double bar brace with a 90 degree ankle stop & inside T- strap, a shoe witharch support & a medial heel wedge, and repeated stretching exercises are needed.

• If correction is not obtained, TA lenghtening may haveto be done

• After correction surgery is needed to prevent recurrence.

• Subtalar arthrodesis of Green & Grice and anterior transfer of of the PL & PB tendons is the procedure of choice

Peroneal tendon transfer for Peroneal tendon transfer for equinovalgusequinovalgus

• Described by Fried & Hendel

• The new site of insertion depends on the severity of deformity & existing muscle power

• When EHL is working, transfer to third cuneiform

• When no functioning dorsiflexor,transfer to the midline of the foot anteriorly

• Peronus longus, FDL FHL or the EHL may be transferred to replace a paralysed tibialis posterior

TALIPES CALCANEUSTALIPES CALCANEUS

• Is a vicious, rapidly progressing deformity caused by paralysis of the triceps surae

PathogenesisPathogenesis

• Weakness of TA- calcaneum cannot be stabilised & push off in walking is lost

• TA becomes thin & elongated• When walking is attempted, calcaneum

rotates dorsally due to the pull of long & short toe flexors &intrinsic muscles;cavus thus develops

• Gravity assists in development of forefoot equinus

• Treatment of talipes calcaneus is difficult because

No appliance can replace a paralysed triceps surae

Gross disparity b/w the strength of all other muscles of the leg & triceps surae. (Cross sectional area of TA far exceeds the sum of that of other muscles of the calf)

Treatment in skeletally immature Treatment in skeletally immature footfoot

• Tendon transfers are indicated early

• Tendons of tib post & peronei should be transferred to the calcaneum to restore plantar flexion

• If these muscles are weak, posterior transfer of the tibialis anterior is indicated.(Drennan)

• If adequate muscles are not available, Westin recommends tenodesis of the tendo Achilles to the fibula.

Westin’s calcaneal tenodesis to Westin’s calcaneal tenodesis to fibulafibula

Treatment in skeletally mature footTreatment in skeletally mature foot

• Plantar fasciotomy+ Hoke arthrodesis

• Alternatively Siffert, Forster & Nachamie described the “beak” triple arthrodesis for severe cavus

• 4 weeks later posterior transfer of the previously named tendons is done

Siffert, Forster & Nachamie beak Siffert, Forster & Nachamie beak triple arthrodesistriple arthrodesis