Congenital pseudoarthrosis tibia

CONGENITAL PSEUDO
ARTHROSIS TIBIA
SAIKRISHNA .K

Definition
• Pseudarthrosis is a
false joint associated
with abnormal
movements at the site

Introduction
• Congenital pseudarthrosis of tibia refers to nonunion
of tibial fracture that develops spontaneously or after
trival trauma in a dysplastic bone segment of tibia
diaphysis.
• CPT is rare & Usually develops in first 2 yrs of life.
• Etiology is unclear.
• Incidence is 1: 250,000
• There is a strong association of CPT with
neurofibromatosis type 1.

• 6% of the patients with Neurofibtomatosis
have the deformity and up to 55% of cases
with anterolateral bowing and
pseudoarthrosis are associated with
neurofibromatosis.
• Some authors have also found anterolateral
bowing to be ultimately associated with
neurofibromatosis in nearly every instance.

• The presence or absence of neurofibromatosis
doesn’t affect the outcome of the tibial
pseudoarthrosis.
• Fibrous dysplasia is seen upto 15% of patients
with Anterolateral bowing.

Neurofibromatosis
• NF-1 occurs due to mutation on the gene coding for
NEUROFIBROMIN on chromosome 17.
• Neurofibromin is expressed in a broad range of cells & tissue
type.
• It negatively regulates Ras activity ( cell proliferation & function)
• It’s deficiency leads to increased Ras activity.
• Affects Ras-dependent MAPK( mitogen activated protein kinase)
activity which is essential for osteoclast function & survival.

Diagnostic criteria of neurofibromatosis
• 6 or more café-au-lait macules (>5mm before
puberty & >15mm after puberty).
• Axillary or inguinal freckling.
• 2 or more neurofibromas or 1 plexiform
neurofibroma.
• 2 or more Lisch nodules.
• Optic glioma.
• A distinctive osseous lesion such as sphenoid
dysplasia or thinning of long bone cortex with or
without pseudarthrosis.
• A first degree relative with NF-1.

Pathology
• Unclear
• Recent studies have shown that there is
hyperplasia of fibroblast with the formation of
dense fibrous tissue.
• This invasive fibromatosis is located in the
periosteum & between broken bones ends
causing compression, osteolysis &
persistance of pseudarthrosis.

Congenital pseudoarthrosis tibia

Pathology
• Paley et al theorized that pathology of
pseudarthrosis is not bony but rather its periosteal
in origin.
This theory was also considered by CODAVILLA a
century ago.
• This theory is supported by following observation
:-
 Thickening with hamartomatous transformation of periosteum.
 Appearance of strangulation of bone with atrophic changes followed by
avascular changes.
 Failure of remodelling of pin tracts leading to stress fractures.

Classification
• There is no universally agreed system based on
both clinical features & radiographic findings.
 CAMURATI - 1930
 ADGLEY - 1952
 BOYD - 1958
 APOIL - 1970
 ANDERSEN - 1973
 CRAWFORD - 1986
 CRAWFORD - 1999
• BOYD & ANDERSEN are commonly used.

Boyd classification
• Boyd divided CPT into 6 types :-
Type 1 :-
 Pseudarthrosis occurs with
anterior bowing.
 A defect in tibia present at birth.
 Other congenital deformities may
be present which may affect the
management of pseudarthrosis.

Boyd classification
Type 2 :-
 Pseudarthrosis occur with anterior bowing & a hourglass constriction of
the tibia is present at birth.
 Spontaneous fractures or after minor trauma.
 Commonly occur before 2 yrs of age.
 Also known as HIGH RISK TIBIA.
 Tibia is tapered, rounded, sclerotic & obliteration of medullary canal.
 Most common type.
 Associated with NF-1
 Poorest prognosis.

Boyd classification
Type 3 :-
Pseudarthrosis develops in a
congenital cyst usually near the
junction of middle & distal third of
tibia.
Anterior bowing may precede or
follow the development of fracture.
Recurrance of fracture is less
common after treatment.

Boyd classification
Type 4 :-
Originates in a sclerotic
segment of bone.
Without narrowing of tibia.
Medullary canal is partially or
completely obliterated.
An insufficiency or stress
fracture develops in the cortex
of tibia & gradually extends
through the sclerotic bone.
Prognosis is good.

Boyd classification
Type 5 :-
 Pseudarthrosis of tibia occurs with a dysplastic fibula.
 Pseudarthrosis of both bone may develop.
 Prognosis is good if the lesion is confined to fibula.
 If the lesion progress to tibia then the natural h/o
usually resembles type 2.
Type 6 :-
 Occurs as an intraosseous neurofibroma or
schwannoma
 Extremely rare.

Crawford classification
• Divided broadly divided into 2 types:-
1-Non-Dysplastic
 Anterolateral bowing with increased density & sclerosis
of medullary canal.
2-Dysplastic
 2aAnterolateral bowing with failure of tubularization.
 2bCystic changes.
 2cFrank pseudarthrosis.

Clinical features
• Associated with anterolateral
bowing of tibia.
• Bowing usually occurs at the
junction of middle & distal third.
• Deformity may be associated
with skin dimple, limb
shortening, dysplasia of fibula &
ankle valgus.
• Usually unilateral.

• If cutaneous signs of neurofibromatosis are
present the diagnosis is readily apparent.

IMAGING
Magnetic resonance imaging
• extent of the disease
• preoperative planning in that the borders for resection can be
defined precisely.
• The area of the pseudarthrosis is hyper intense on fat-suppressed
and T2-weighted images and slightly hypo intense on T1-weighted
images with contrast enhancement after administration of
gadolinium.
Computed tomography scan
Confirm radiographic findings.
Total bone scintigraphy
Level of the pseudarthrosis .

Problem
• Except for the resolving form, the natural
history of tibial dysplasia is extremely
unfavourable,and once fracture occurs there is
little tendency for the lesion to heal
spontaneously,particularly for fractures
occuring before the walking age.
• Regardless of the treatment method
used,there is general pessimism regarding the
quality and longevity of the union attained.

AIMS
1. Achieve union
2. Prevent refracture
3. Correct limb length inequality
4. Correct associated growth abnormalities
5. Prevent ankle deformity and arthritis.

1. Strategies to achieve union
1. Microvascular free fibular transfer.
2. the Ilizarov technique
3. Bone grafting with intramedullary nailing.
• Excision of the pseudarthrosis should be an
integral part of the procedure.

2. Strategies for minimizing the risk of
refracture
• Splint the limb in an orthosis until skeletal
maturity.
• Retain an intramedullary nail until skeletal
maturity.

3. Strategies for dealing with
shortening of the limb
● Minimize the extent of shortening by
obtaining union of the pseudarthrosis as early
as possible.
● Established shortening can be addressed by
limb equalization procedures

4. Strategies for minimizing valgus
deformity of the ankle
● Ensure union of the fibular pseudarthrosis.
● Retaining an intramedullary rod that crosses
the ankle joint can also prevent ankle
deformity although the motion is lost.

Prophylaxis
• Once the diagnosis of a non resolving
anterolateral bowing of the tibia has been
made the first step is to prevent fracture if
possible.
• In an infant before walking age,no specific
treatment is needed other than education of
the caretakers.

• Once the child begins weight bearing prophylactic
bracing should be attempted although there is no
documentation that such a program can prevent
a fracture.
• A clam shell like orthosis that provides
circumferntial support is usually recommended.
• Protection of the unfractured tibia should be
continued indefinitely till skeletal maturity or
until patient approaches skeletal maturity.

SURGICAL OPTIONS
1. Vascularized fibular graft
2. External fixation
3. Intramedullary rod
4. BMP
5. Electrical stimulation

Intra medullary fixation
• The procedure of choice for the first attempt
to gain union entails resection of
pseudoarthrosis,shortening and fixation with
an intramedullary rod and autogenous bone
grafting.
• The procedure can be performed at any age
and rates of union of around 85% have been
reported although solid long lasting union
without deformity is another matter.

Williams technique
• Williams conceived the novel technique of
threaded male and female components of the
rod that when joined,can be placed antegrade
through the pseudoarthrosis site and out the
bottom of the foot.
• After retrograde insertion back in to the proximal
intra medullary of the tibia the male end is
unscrewed and removed from thebottom of the
foot with the female threaded rod left
intraosseously in the tibia or across the ankle in
talus/calcaneus.

• The undesirable effect of ankle immobilisation
by IM fixation is thought ot be necessary evil
to adequately immobilise the small distal
fragment.
• As the tibia grows the foot and ankle may
eventually grow off the distal end of the IM
rod and thus allow ankle to regain motion

• The possibility of ankle valgus is also almost
inevitable especially if there is a fibular
pseudoarthrosis despite the acheivement of a
solid union.
• Limb length discrepancy is yet another untoward
event with shortening at maturity averaging as
much as 5 cm.
• Weak and stiff ankle and subtalar joint secondary
to cross ankle fixation producing a poorly
functioning foot.

• The need for fibular surgery remains
controversial. Researchers concluded that it is
crucial to resect a fibular pseudarthrosis or, if
the fibula is intact, to perform a fibular
osteotomy in order to achieve optimal limb
alignment and union.

1. Vascularized fibular graft
• The procedure entails harvesting a long segment of the opposite fibula along with its
vascular pedicle.
• This is transferred into the gap created after radical excision of the pseudarthrotic segment.
• The vessels of the transferred fibula are anastomosed to the local vessels. The transferred
fibula is fixed securely to the tibia.

• Intra medullary fixation of the donated fibula
is contraindicated theoretically because of the
possibility of disturbance of blood supply of
the microvascular graft.
• Because the transfer brings tissue with its own
blood supply, free fibular vascularised transfer
has been recommended as procedure of
choice for gaps > 3cm after resection of
pseudoarthrosis.

• Success rate for free fibula transfer is 92%-
95% if union alone is considered.
• Refracture has been reported in a third of the
patients probably a direct result of not being
able to apply a permanent intra medullary
fixation and thus ignoring a major principle in
treatment.

• Morbidity of the donor leg—
• The distal end of fibula must be synostosed to
the tibia(Langenskiold procedure) or the fibula
of the donor site must be reconstructed with
bone graft to prevent ankle valgus.
• In addition weakness may ensue in the donor
leg due to resection of origins of flexor
muscles.

Bone morphogenic protein
• BMP2 is useful to speed up the union rates in CPT
• BMP 7 seems to be ineffective in the absence of an actively
differentiating osteoblastic cell line.

Electrical stimulation
• Electrical stimulation doesnot correct existing
deformities and thus its appplication is
probably limited to the earlier phases of
pseudoarthrosis treatment when union is the
primary goal.

Amputation
• The final function in a patient who has
undergone multiple operations but must still
protect the leg in an orthosis may well be
worse than if an earlier amputaion and
prosthetic fitting had been performed.

Complications
1. Refracture
2. Malalignment of the tibia
3. Limb length discrepancy
4. Ankle valgus
5. Ankle stiffness

1. Refracture.
• 14% to 60%.
• Anatomic alignment of the tibia and fibula minimize the risk
of re-fracture.
• Intramedullary rod and external bracing must be continued as
effective protection against re-fractures.

2. Malalignment of the tibia
• Diaphyseal malalignment of the tibia (procurvatum or valgus
deformity) are progressive and do not remodel

3. Limb length discrepancy
• Residual limb length discrepancy following successful
union is a major problem.
• Growth abnormalities of the tibia, fibula, and the
ipsilateral femur abnormalities are also noted with CPT
• which include inclination of the proximal tibial physis,
posterior bowing of the proximal third of the tibial
diaphysis, proximal migration of the lateral malleolus.

4. Ankle valgus
• Compromises functional outcome.
• Progressive ankle valgus is a problematic postoperative
donor-site morbidity of a vascularized fibular graft in children.
•
• Tibiofibular metaphyseal synostosis (the Langenskiöld
procedure)

5. Ankle stiffness
• Progressively regresses once intramedullary
rod is removed from ankle.
• Pain secondary to degenerative changes of the
ankle can be treated with limitation of activity
and shoe modification.
• Severe pain may require ankle arthrodesis

Follow up.
• till skeletal maturity to identify and rectify
residual problems.

Take Home message.
• Rare.
• The natural history of the disease is extremely unfavorable and
• Little or no tendency for the lesion to heal spontaneously.
• challenging to treat effectively
• Aims to obtain a long term bone union, to prevent limb length discrepancies,
to avoid mechanical axis deviation, soft tissue lesions, nearby joint stiffness,
and pathological fracture.
• The key to get primary union is to excise hamartomatous tissue and
pathological periosteum.
• Age at surgery, status of fibula, associated shortening, and deformities of leg
and ankle play significant role in primary union and residual challenges after
primary healing.
• Surgical options such as intramedullary nailing, vascularized fibula graft, and
external fixator, have shown equivocal success rate in achieving primary union
• Amputation must be reserved for failed reconstruction, severe limb length
discrepancy and gross deformities of leg and ankle..

Congenital pseudoarthrosis tibia

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