Treatment of Pseudarthrosis of
the Tibia
Dr. Alok Umre, I.G.M.C., Dept. Of
Orthopaedics, Nagpur.
Introduction –
Pseudarthrosis of
Tibia two types
a) Congenital b)
Acquired
a)
Congenital Pseudarthrosis of Tibia
Defination
Condition of unknown origin in which discontinuity of the bone at
the junction of the middle and distal thirds or beyond is present
at birth or develops thereafter during the growth period,
permitting persisting abnormal mobility and creating the illusion
of a false joint.
Incidance – 1
in 250,000 live births.
Classification -By
Boyd –
Type 1 - with
anterior bowing and a defect in the tibia present at birth.
Type 2 - with
anterior bowing and an hourglass constriction of the tibia
present at birth.-
Most common type.
-
Poorest prognosis
-
Spontaneous fractures occurs before 2 years of age following
minor trauma hence called high-risk tibia.
-
Medullary canal is obliterated and is often associated with
neurofibromatosis.
-
Recurrance is rare after skeleton maturation
Type 3 –
Develops in a congenital cyst, usually near the junction of the
middle and distal
thirds of the
tibia.
Type 4 –
Orginates in a sclerotic segment of bone without narrowing of the
tibia. An “insufficiency” or “stress”
fracture develops in the cortex of the tibia.
Type 5 –
Occurs with a dysplastic fibula.
Type 6 –
Occurs as an intraosseous neurofibroma or schwannoma.
-
Extremely rear
Aetiology and
Pathology
It is the
combination of bowing and dysplasia that is the most likely to
lead to intractable pseudarthrosis.
The commonest cause
of the dysplasia was neurofibromatosis. (Hardinge –1972)
Localizd dysplasia
in association with congenital anterior angulation of the tibia
with pseudarthrosis following osteotomy or injury is the second
most common cause.
Less frequent cause
is fibrous dysplasia which can present with a cystic lesion with
a fracture at birth.
Late onset type
developing in a tibia which is normal at birth but develops
progressive anterior bowing between the ages of 4 and 12 years
followed by a stress fracture and pseudarthrosis.
Pathology
Type 1 –
Complete defect in the bone typical at the birth.
Type 2 –
Cogential bone cyst occurs in the lower third of the tibia
Type 3 –
Congenital bowing of the tibia complicated by a fracture
resulting in pseudarthrosis. Anterolateral bowing is usually
predisposed to this condition.
Hence congenital
bowing and congenital cysts are called pseudarthrotic lesions.
Clinical Picture
– Baby presenting with antero lateral bowing of a dysplastic
tibia and fibula.
May present with fracture secondary to a cystic lesion.
May present with fracture with the fibula with
pseudarthrosis together with a
bowed abnormal but intact tibia.
May present with signs of neurofibromatosis such as café au lait
spots in the baby or in any family member.
Less often, a child presents with fracture of the tibia due to an
injury and is found to have bowing of the tibia.
Differential
Diagnosis
1)
Anterior or antero lateral bowing occuring in osteogenesis
imperfecta or rickets.
Differentiating
feature generalized involvement of the skeleton and the
characteristic features of the condition.
2)
Congenital posterior angulation of the tibia in which tibia
is curved and thinner than on the normal side and there are
changes in the thickness of the cortex.
Differentiating
feature - Direction of the curvature
In pseudarthosis the direction is never postero-medial but is
antero-lateral.
3)
Anterior bowing of the tibia which is feature of congenital
absence of the fibula or fibular hypoplasia.
Differentiating
feature – Acute curvature at birth with a dimple in the skin
overlying the apex, an equinovalgus deformity of the foot and, in
most instances, by absence of one or more lateral rays of the
foot.
Prognostic
Factors
1)
Bones Affected – Bad prognosis if tibia and fibula are
ununited in neurofibromatosis and better when only the tibia is
ununited in congenital angulation of the tibia with dysplasia.
2)
Level of the pseudarthrosis – More proximal the level,
better is prognosis.
3)
Mobility of the pseudarthrosis – More the mobility worse is
the prognosis.
4)
Bone quality – Sclerotic lesion with an obliterated
medullary canal but a narrow line of pseudarthrosis has a much
better prognosis than an atrophic bone with pointed ends,
displacement and angulation .
More the
length of dysplasia worse is the prognosis.
Severe
cystic lesions with fibrous dysplasia have a poor prognosis.
Treatment
Treatment
is divded in three type
1)
Prophylactic - Directed toward the prepseudarthrosis lesions.
2)
Active – Directed toward the fully developed congenital
pseudarthrosis.
Prohylactic –
Protection by an orthosis and the child guarded against activity
excesses.
-
If fracture is imminent and child activity is cannot be
controlled prophylactic reinforcement with bone transplants,
preferably autogenous or homogenous cortical bone struts, is
indicated.
-
If cyst is present than bypass grafting is done. Later on the
defect is curreted and filled with bone transplants and
immobilized in the cast until the defect is obliterated.
-
Osteotomy is contraindicated
Active - There
is no ideal or specific method special techniques giving best
result include
1)
Bypass grafting (Mcfarland, 1951)
2)
Double onlay grafts (Boyd, 1941)
3)
Intramedullary nailing and onlay grafts (Charnley, 1956 van nes,
1966)
4)
Fragmentation of the tibial shaft and intramedullary rod
fixation. (Sofield & Miller, 1959, Sofield 1971).
5)
Composite skin and bone pedicle grafting from the opposite tibia
(Farmer ,1956)
6)
Vascularized fibular grafts (Pho et al, 1985, Simonis et al.,
1991)
7)
Ilizarov bone transport technique.
8)
External skeletal fixation (Fixateur externe)
9)
Stimulation of osteogenesis by bone transplant and electrical
stimulation.
1)
Mcforland by pass grafting – It is useful in which the
bowing is not too distal.
Giving
sufficient tibia distally for placing of the distal end of the
graft. The affected tibia is exposed extrapenioseteally in its
whole length. A cortico-cancellous graft is taken from the middle
two-thirds of the length of the normal tibia including the
anterior crest and of a width of between one-half and two-thirds
of the bone. The graft is shaped to a point at its ends. It is
inserted through a slot made in the upper part of the affected
bone away from the site of the abnormal bone. Distally a V-shaped
slot is made in the distal fragment and the graft is sprung into
place by opening the bowing as far as possible and using a
suitable length of graft such that it fixed itself in place
without additional fixation.
The
graft must be in line with the true longitudional axis of the
limb or it may fail. After closure the limb is immobilized in a
groin-to-ankle plaster for 8 weeks without bearing weight and for
a further 8 weeks in a walking plaster.
2)
Boyd double onlay graft
Useful
in which there is sufficient bone distally to take the graft and
screws and in which there is not too great an angle of
bowing. The grafts are ideally obtained from the opposite tibia
along most of the middle two-thirds and for the whole width of
the bone, half the weight being used for each graft. The affected
bones exposed, pseudarthrosis excised along with the periosteum,
bowing corrected, grafts applied on each side and fixed with four
screws and than limb is immobilised for 16 weeks.
3)
Charnley intramedullary nail and onlay graft
This
method has a particular value in partients with a low
pseudarthrosis. Disadvantage is stiffness of sub-talar joint and
ankle joint for considerable period.
4)
Fragmentation and intramedullary pinning by Sofield and Millar
It
is useful for lesions in which there is small distal fragment.
Disadvantage is it may retain two much of the dysplastic bone and
its periosteum.
5)
Free vascularized fibular graft by Pho et al. Donor fibala is
first harvested from the normal leg under tourniquet through a
postero-lateral incision. The fibula with its peroneal vascular
bundle and musculo-periosteal vessels is dissected free from
surrounding tissues. The pseudarthrosis in the affected limb is
exposed through an antero-medial incision and excised. The
fibular graft is slotted into the medullary cavity of the
affected tibia, proximal end first and then distal end the graft
being fixed with transverse screws and k-wires. Major advantage
of this method is that it allows all the affected dysplastic bone
and its abnormal surrounding periosteum to be removed in a
pseudarthrosis associated with neurofibromatosis, angulation
can be corrected and some loss of length regained. This procedure
can be used in baby as young as 18 month though ideal age is 5 to
6 years. Leung (1983) recommends the use of an iliac crest graft
if the child is more than 4 years simonis et al. (1991) recommend
its use if defect is more than 3 cm. or shorting on more 5 cm.
7)
Ilizarov method
Principles
of percutaneous transosseous osteosynthesis by alternate
distraction and compression of pseudarthrosis and of controlled
distraction with spontaneous bone formation in leg lengthening
and the closure of bone defects with k-wires and circular frames
developed by Ilizarov has a major role in treatment of
pseudarthrosis. In patients with atrophic pseudarthrosis,
compression is applied for a period until early callus forms and
is then replaced by distraction leading to union in hypertrophic
pseudarthrosis, immediate distraction is used. Distraction is of
1 mm/day after waiting for 7 to 10 days to stimulate callus
formation.
8)
External skeletal fixation
Useful
for maintaining length, when the bone structure about the
structure about the defect is inadequate, and when poor soft
tissue about the pseudarthrosis will not permit local fixation
device.
X-Ray findings
– Lack of bone formation at the junction of the middle and
distal thirds.
-
Varying degrees of tapering sclerosis, and oblieration of the
medullary canal. The distal tibial segment is usually angulated
backward, resulting in equinus of the foot.
-
Cyst formation and ground glass appearance of the affected part.
