CONGENITAL ANTEROLATERAL BOWING OF THE TIBIA: CONGENITAL PSEUDARTHROSIS

CONGENITAL PSEUDOARTHROSIS TIBIA

Dr. J.FAISAL Moderator :DR.SIDDHARTH SHETTY Dept of Orthopaedics KSHEMA

Definition

It is a specific type of non union which is either present or incipient at birth.

Its misnomer ( infantile pseudoarthrosis).

Most difficult and challenging deformities

Epidemiology

1 : 250,000 live births

50 % - 90 % associated with neurofibromatosis ( cutaneous and osseous lesion)

Usually left

Bilateral - rare.

Aetiology

Aplasia/ dysplasia portion tibial shaft nutritional disturbances

Increased Intrauterine pressure

Amniotic bands

Part of neurofibromatosis

Pathology

Middle and lower 3rd junction.

Ends of bone sclerosed with gap

Biopsy

Dense, cellular, fibrous connective tissue with areas of cartilage formation

Fibroblasts rather than Schwann cells or perineural cells

Rarely neurofibromatosis tissue

Hamatomatous tissue.

Clinical presentation

Angular deformity since birth (anterolateral).

If acute fracture then painful and unstable

If not bony prominence with dimple over skin

Cafe-au-lait spots

Positive family history

Boyds Classification

Type -I

Anterior bowing and defect in the tibia at birth.

Type-II

Anterior bowing and hour glass constriction at birth

Fracture < 2 years of age

Tibia tapered, sclerotic , medullary canal obliterated

Associated with neurofibromatosis

Type III

Congenital Cyst middle & distal third of tibia

Anterior bowing may precede or follow fracture

Excellent results.

Type IV

Sclerotic segment middle/ distal 3rd

No narrowing

Medullary canal partially/ completely obliterated

Insufficiency/ stress Fracture do not heal

Type V

Pseudo arthrosis tibia with dysplastic fibula

Pseudo arthrosis tibia/ fibula/ both

Prgnosis good if only fibula

Type VI

Intra osseous neurofibroma / schwannoma

Rare

Aggressive treatment

Prognosis

Simple best

Cystic

Scerlotic

Sclerotic type with pseudarthrosis of the fibula worst

Preoperative Management and Planning

Prophylactic treatment orthosis - delay or prevent fracture - subsequent pseudarthrosis

Orthosis are worn for years.

Knee ankle foot orthosis

With growth and in the absence of a fracture, the tibial bowing usually improves

When to discontinue orthosis

Tibia has straightened sufficiently

Medullary canal has reconstituted

Adequate cortical thickness

Skeletal maturity is approached

Long-term reports of successful orthotic management in adolescents or adults not available

Goals of surgery

Obtaining union at the pseudarthrosis site

Maintaining union throughout growth and development

Obtaining an acceptable limb length at maturity

Timing of surgery

Previously >4 years

Now recommend early surgical intervention and revision if require

Masserman et al - union related to pathologic process than the age at surgery

Earlier union normal growth of the distal tibial epiphysis and less limb length discrepancy

Surgical options

Bone grafting alone

Bone grafting and internal fixation

Electrical stimulation

Microvascular bone grafting

Ilizarov external fixation

Amputation

Bone grafting

Prophylactic

Deformed tibia

Before pathological fracture

To strengthen the deformed area

Decrease the risk of pathological fractures

Mcfarland procedure

Corticocancellous graft from opposite tibia

Placed posteriorly

Spanning the deformity

In the normal biomechanical axis of weight bearing

53% best result out of all other

Paterson - Indicated primarily for cystic prepseudoarthrosis

Tachdjian - Suggested concomitant curettage and bone grafting of any cystic lesions

Bone Grafting & Internal Fixation

Excision of pseudarthrosis

Correction of angular deformity

Rigid internal fixation

Bone graft good outcome. Better primary union

Stabilization

Compression plates (difficult in achieving fixation)

Intramedullary rods

Tibial or dual tibial and fibular intramedullary rods

Transfix the ankle and subtalar joints - stabilize the distal tibial segment

Joints are progressively freed growth of the tibia

Proximal migration of the rod

Postoperatively

Unilateral hip spica cast - long-leg cast - knee ankle foot orthosis

Anderson et al. - 10 of 13 pseudarthroses healed by intramedullary rod technique

Extending IM rods + bone graft

These rods extended with growth

Decreasing the need for revision surgery

Protecting the union until skeletal maturity

Do not the include ankle or subtalar joint

Fern et al

Outer sleeve across the pseudarthrosis site

Provide more strength and reduce refracture.

Expand up to a maximum of 6.4 cm.

PRE-OP POST OP

Fractured dysplastic tibia

IM rod fixation and grafting

Tenuous union achieved

Fibula unhealed - ankle valgus

Distal tibialfibular fusion -prevents valgus

Electrical Stimulation

Used in conjunction with internal fixation and bone grafting

DC bone growth stimulators Implanted

External stimulation devices with pulsating electromagnetic fields

Electrical Stimulation

Spindled bone ends, a large gap, and gross mobility - poor prognosis

Cystic or sclerotic transverse fracture and a gap of less than 5 mm - better responses

Mode Of Action

Induce bone formation

Alone effective in 50%

Remainder, additional procedures are necessary before primary union can be achieved

Microvascular Bone Graft

Vascularized rib

Vascularized Iliac crest

Vascularized Fibula grafts best

5 basic steps of free vascularized bone grafts

Harvest of the vascularized bone with an intact vascular pedicle

Excision of the tibial pseudarthrosis and abnormal tissue

Fixation of the vascularized bone in situ

Microvascular anastomosis

Skin closure

Vascularized fibula graft - performed at 17 months of age

Internal fixation was not used

Ends of fibula graft were inserted into medullary canal proximally and into metaphysis distally

Two months

Extensive subperiosteal new bone formation and hypertrophy of the graft

Twenty-two months later

The tibia is healed

Leg is protected in a knee ankle foot orthosis

Thirty-three months

Tibia has healed well

Medullary canal is reforming in the area of the vascularized fibula.

Ilizarov-Advantages

Provides excellent stability

Complete resection of the pseudarthrotic area

Advantages

Enables weight bearing ,which stimulates healing of bone and soft tissues

Can transport fibula distally

Donot interfere other treatment if it fails

Disadvantages

Time-consuming

Not easy to perform

Pin track infections, fracture, ankle valgus, and ankle stiffness

Used in four ways

Compression of the pseudarthrosis

Compression with metaphyseal tibial lengthening

Compression followed by distraction for hypertrophic nonunion

Distraction alone for hypertrophic nonunion

Amputation

Amputation with appropriate prosthetic fitting allows rapid rehabilitation and return to normal function

McCarthy-criteria/indication

Failure to achieve bony union after 3 surgical attempts

Significant lower-extremity length inequality (usually 5 cm or greater)

Development of a deformed foot

Undue functional loss from prolonged hospitalizations

High medical costs

Boyd or Symes amputation - procedure of choice

Preserves the heel pad and distal tibial epiphysis, which allows end bearing on the stump

Bone and skin are lengthened as a unit to avoid problems with overgrowth

B/K amputation at pseudarthrosis poor end-bearing stump

Abnormal tissue and previous surgical scar -poor skin coverage increased breakdown

Overgrowth and frequent revision

Amputation above the pseudarthrosis site provides better skin coverage

Problems - Bony overgrowth

Rehabilitation and Postoperative Principles

To restore maximum strength and function after healing

Each surgical procedure has its specific postoperative regimen

But all share long-term orthotic management

Protection is required at least until skeletal maturity and perhaps even longer

Decision

Radiographic appearance of the tibia

The degree of residual deformity

Presence or absence of a reconstituted medullary canal

Extremity needs to be protected with a plastic ankle foot orthosis (prevent recurrent refracture)

Orthosis are worn for years. With growth and in the absence of a fracture, the tibial bowing usually improves

Complications

Stiffness of the Ankle and Hindfoot

Refracture - casting or removal and replacement of the intramedullary rod with additional bone grafting

Valgus Ankle Deformity

The distal tibial fragment must be fixed so that valgus deformity of the ankle is corrected at the time of placement of the intramedullary rod

Long-term bracing is mandatory during the growth years

Surgical treatment - Langenskild procedure (tibio fibular synostosis)

Tibial Shortening

Anticipated in almost all children - Anderson et al. 4 cm.

Contralateral epiphysiodesis or limb lengthening of the proximal tibia.

Intramedullary nailing with bone grafting, with or without electrical stimulation, is recommended for an established pseudarthrosis.

Conclusion

Minimize the number of operative procedures

Maintain as normal function as possible

Prevention of fractures - critically important

Best results with respect to union are achieved with a vascularized fibula graft or intramedullary rod

Initial surgical procedure should be the latter

Pseudarthrosis cannot be satisfactorily healed

Symes amputation and prosthetic replacement permit restoration of relatively normal function

Thank you