- Congenital pseudarthrosis is a specific type of nonunion that at birth is either present or incipient.
- Its cause is unknown
- Asoociated with Neurofibromatosis
- Congenital pseudarthrosis most commonly involves the distal half of the tibia and often that of the fibula in the same limb.
Fibula
- often precedes or accompanies congenital pseudoarthrosis in the ipsilateral tibia.
Grading
i. bowing of the fibula without pseudarthrosis,
ii. fibular pseudarthrosis without ankle deformity,
iii. fibular pseudarthrosis with ankle deformity, and
iv. fibular pseudarthrosis with latent pseudarthrosis of the tibia.
- Sometimes develops between the time of bone grafting of a pseudarthrosis of the tibia and skeletal maturity;
because the lateral malleolus becomes displaced proximally, a progressive valgus deformity of the ankle
develops.
Treatment
- Before skeletal maturity: the ankle can be stabilized by an ankle-foot orthosis.
- At maturity: any significant deformity can be treated by supramalleolar osteotomy made through essentially
normal bone, and union of the osteotomy can be expected.
-
Synostosis (Langenskiöld)
o for children, to prevent this valgus deformity or halt its progression.
o a synostosis between the distal tibial and fibular metaphyses.
o securing union by bone grafting may be as difficult in the fibula as in the tibia, an operation that prevents the ankle deformity without grafting in fibular pseudarthrosis is useful .
Tibiofibular Synostosis Langenskiöld Technique:
• Make a longitudinal incision anteriorly over the distal fibula.
• Divide the fibula 1 to 2 cm proximal to the level of the distal tibial physis, and excise the
cone-shaped part of the distal fibular shaft.
• In the lateral surface of the tibia, at the level of the cut surface of the fibula, and at the attachment of the interosseous membrane, make a hole as wide as the diameter of the fibula. Proximal to the hole, remove the periosteum and interosseous membrane from the tibia over an area of several square centimeters.
• From the ilium, obtain a bone graft the same width as that of the hole in the tibia and long enough to extend from the lateral surface of the fibula into the spongy bone of the tibial metaphysis.
• Insert the graft perpendicular to the long axis of the limb so that it rests on the cut surface of the fibula and extends into the slot in the tibial cortex.
• Pack spongy iliac bone in the angle between the proximal surface of the graft and the lateral surface of the tibia.
• Apply a cast from below the knee to the base of the toes.
Aftertreatment
At 2 months, full weight bearing in the cast is allowed, and at 4 months the cast is discontinued.
Tibia
- Congenital pseudarthrosis of the tibia is rare,
- incidence – 1:250,000 live births.
- 50% to 90% association with neurofibromatosis, including skin and osseous lesions.
Classification
Boyd classified congenital pseudarthrosis of the tibia into the following six types:
Type I pseudarthrosis: with
anterior bowing and a
defect in the tibia present at birth. Other congenital deformities may be +nt, that affect its management.
Type II pseudarthrosis: with
anterior bowing and an
hourglass constriction of the tibia present at birth. Spontaneous #, or # after minor trauma, in <2 yrs age. This is the so-called
high-risk tibia. The tibia is tapered, rounded, and sclerotic, and the medullary canal is obliterated. This type is the most common, is often @ with neurofibromatosis, and has the poorest prognosis. Recurrence of the # is common during the growth period, but decreases in frequency with age and generally ceases to occur after skeletal maturation.
Type III pseudarthrosis: develops in a
congenital cyst, usually near the junction of the middle and distal thirds of the tibia. Anterior bowing may precede or follow the development of a fracture. Recurrence of the fracture after treatment is less common than in type II, and excellent results after only one operation have been reported to last well into adulthood.
Type IV pseudarthrosis: originates in a
sclerotic segment of bone in the classic location without narrowing of the tibia. The medullary canal is partially or completely obliterated. An “
insufficiency” or “stress” fracture develops in the cortex of the tibia and gradually extends through the sclerotic bone. With completion of the fracture, healing fails to occur, and the fracture widens and becomes a pseudarthrosis. The prognosis for this type generally is good, especially when it is treated before the insufficiency fracture becomes complete.
Type V pseudarthrosis of the tibia occurs with a
dysplastic fibula. A pseudarthrosis of the fibula or tibia or both may develop. The prognosis is good if the lesion is confined to the fibula. If the lesion progresses to a tibial pseudarthrosis, the natural history usually resembles that of type II pseudarthrosis.
Type VI pseudarthrosis occurs as an
intraosseous neurofibroma or
schwannoma that results in a pseudarthrosis. This is extremely rare. The prognosis depends on the aggressiveness and treatment of the intraosseous lesion.
Treatment
- depends on the age of the patient and the type of pseudarthrosis.
- A true congenital pseudarthrosis of the tibia does not heal
- The decision must be made whether to attempt to secure union or if amputation is the treatment of choice. when treated by casting alone.
- Factors favoring
amputation-
o anticipated shortening of > 2 or 3 inches (5 to 7.5 cm),
o a history of multiple failed surgical procedures
o , and stiffness and decreased function of a limb that would be more useful after an amputation and fitting with a
prosthesis
- For the tibia with a cyst in the medullary canal (type III): prophylactic
curettage and
autogenous iliac bone grafting are recommended. The limb is immobilized in plaster until the graft has united, and then a
patellar tendon–bearing brace is worn until skeletal maturity is reached. .
- A tibia with anterior bowing and a narrow, sclerotic canal (type II or the high-risk tibia): often fractures during the first 2 years
-
Established congenital pseudarthrosis of the tibia: was treated in the past by bone grafting or amputation. Osseous union probably is more difficult to obtain in this condition than in any other. Or, Early primary amputation with an appropriate prosthesis. of life. Initially, bracing may be beneficial for an anterolaterally bowed tibia with a narrow canal in which a fracture has not developed, stable and well-adjusted knee-ankle-foot orthosis with an anterior shield in the prepseudarthrotic stage delayed fracture and pseudarthrosis and allowed patients to reach an older age before undergoing surgical treatment. Its important because they found better healing rates in children > 3 years at the time of surgery than in younger children. When a fracture does occur, the treatment is surgery.
-
Poor Prognostic factors: neurofibromatosis, dysplastic lesions, and multiple surgical procedures
- even when union is obtained, leg-length discrepancy and malalignment may require surgical correction.
- age, the difficulty in obtaining union, and the anticipated residual shortening and other deformities of the tibia should union be obtained all must be considered.
- In an infant or young child, bone grafting is indicated as early as feasible.
- Although the likelihood of obtaining union increases with increasing age, especially after puberty, the longer grafting is delayed, the shorter and more poorly developed the leg will be.
- When union is obtained in a young child, weight bearing in a brace results in more normal development of the limb.
- The child's parents should be told that treatment often consists of several operations, and that even then amputation may be necessary later because of failure to obtain union.
- If grafting is indicated, but for some reason must be delayed, the limb should be braced to prevent increased angulation at the pseudarthrosis.
- In an older child, bone grafting is indicated unless shortness or other deformity of the limb is such that function would be better after amputation and fitting with prosthesis.
- The heavy cuff of tissue surrounding the bone at the pseudarthrosis, the presence of this tissue, whether congenital or a result of a fracture may decrease bone production and consequently healing. Any operation for congenital pseudarthrosis should include complete excision of this tissue.
-
Bone grafting remain the mainstay of treatment for congenital pseudarthrosis of the tibia.
- Intramedullary rodding technique in congenital pseudarthrosis of the tibia; refractures may occur. Best results with intramedullary rod fixation, bone grafting, and the use of an osteostimulator.
-
recent technique is the
free vascularized bone graft with either fibular or iliac crest grafts.
- most effective methods were the
Ilizarov method and
vascularized fibular grafting.
Goals of treatment of the biological problems:
(1) resection of the pseudarthrosis to provide stability, the basic requirement for bony consolidation;
(2) correction of length discrepancy and axial deformity;
(3) achievement of fusion; and
(4) correction of additional problems around the main deformity, such as alignment, leg-length discrepancy, and ankle valgus.
Plating and rodding
(1) failed to provide adequate stability for the pseudarthrosis to heal, and that
(2) when this kind of fixation was used, too little of the pseudarthrotic bone was resected.
(3) plating, rodding, and vascularized fibular transfer do not provide correction of shortening and valgus ankle deformity.
Ring fixator :
Advantages;
(1) provides excellent stability;
(2) allows complete resection of the pseudarthrotic area regardless of the size of the resected segment because the device allows lengthening or segmental bone transport;
(3) enables weight bearing during the whole time of treatment, which stimulates healing of bone and soft tissues;
(4) can be used to transport the fibula distally; and
(5) does not prohibit other treatment methods if this method fails.
Disadvantages :
(1) it is time-consuming,
(2) not easy to perform; and,
(3) varying degrees of complications, such as pin track infections, fracture, ankle valgus, and ankle stiffness.
- surgery should not be done in children <3 years old, and, if possible, surgery should be postponed until age 5 years.
- For established pseudarthroses, initial treatment should be intramedullary rodding and bone grafting.
Vascularized fibular grafts may be indicated for pseudarthroses with gaps of more than 3 cm and for pseudarthroses in which multiple surgical procedures have failed.
The
duration of immobilization and the type of cast are determined by the amount of healing noted on clinical and radiographic examinations. When healing is sufficient, the
hip spica cast is discontinued, and an
above-knee cast is applied. Removal of the cast and institution of progressive weight bearing usually are possible 3 to 9 months after surgery. A
knee-ankle-foot orthosis or
patellar tendon–bearing brace is worn until skeletal maturity is reached.
Complications
Stiffness of the Ankle and Hindfoot
A stiff ankle should be expected until the distal tip of the rod is proximal to the ankle joint after longitudinal growth of the distal end of the tibia. Even if stiffness persists, it rarely hampers functional results.
Refracture
Refracture is common in patients with pseudarthroses, despite apparently solid clinical and radiographic union. Refracture can be managed with casting or removal and replacement of the intramedullary rod with additional bone grafting. Because of the likelihood of refracture, removal of the rod after union is not recommended until skeletal maturity has been reached.
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. Intraoperative fluoroscopy is useful for monitoring this procedure. Long-term bracing is mandatory during the growth years to minimize progressive valgus ankle deformity, or surgical treatment with the Langenskiöld procedure may be indicated.
Johnston, in patients treated with intramedullary rods, found that valgus deformity was significantly more frequent when the fibula was left intact than when fibular osteotomy was done (with or without fibular fixation). In addition, the presence of fibular insufficiency (fracture or prepseudarthrotic lesion) was highly prognostic for subsequent valgus deformity, whether or not the fibula eventually healed.
Tibial Shortening
Tibial shortening should be anticipated in almost all these children. The maximal projected shortening was 4 cm. In selected patients, tibial shortening can be treated by a well-timed 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. The
vascularized graft or the Ilizarov technique may be useful initially in severe cases with significant shortening and a wide nonunion or in patients in whom medullary nailing and standard bone grafting procedures fail.
Ref: Canale & Beaty: Campbell's Operative Orthopaedics,
11th ed.
