Children’s Orthopaedic & Spine Care Center

Congenital Pseudoarthrosis Of Tibia

Congenital pseudoarthrosis of the tibia (CPT) is a condition in which the shin bone (Tibia) develops a deformity in the first year of life, and then develops a fracture (break) which does not heal. This condition is typically detected in early childhood and is the most frequently observed type of congenital pseudoarthrosis. However, the condition is rare – it is seen in 1 out of 250,000 live births.

Although the condition is termed “congenital,” a true non-union is not present from birth in the majority of cases. Rather, the affected tibia presents with an anterolateral bow, with bone on radiographs showing abnormal bone or a cystic pre-fracture, and failure of tubulation early in life. In one fifth to one half of the cases, this Segmental bone abnormality and bowing may then progress to fracture.

The exact cause of CPT is unknown. Most of the established literature contends that cells from pseudo-arthrotic lesions demonstrate decreased healing and bone forming capability.

Anteroposterior and lateral radiographs depicting an anterolaterally bowed, dysplastic tibia and fibula.

How to diagnose Congenital Pseudoarthroisis of Tibia?

Abnormal Bowing of the leg may be discovered atbirth or in the first weeks in life. You may see a bowing ofthe shin bone (tibia). In some cases, a discontinuity betweenthe two parts of the tibial segment may be seen.When the break in the Tibia is present at birth, the condition is called Severe neonatalform or primary pseudarthrosis. In some cases, a pathological fracture develops when the child begins walking. This is also called as secondary pseudarthrosis.

An older child may present to uswith simple bowing of the shin bone to more extensive bonedeformities with severe bowing in one ortwo bones of the leg. The leg often appears short. The radiograph may reveal pathologicalfracture and pseudarthrosis.

Normally, Congenital Pseudoarthrosis of the Tibia is present in one leg, located at the junction of themiddle and distal thirds of the tibial segment with no predominancefor sex or side. The fibula (thinner bone of the leg) is also affected in morethan half the cases.

Congenital Pseudoarthrosis may be an isolated condition or be associated with a condition called Neurofibromatosis. A careful history and a complete clinical examination of your child at our clinic will help to differentiate a diagnosis of isolated CPT from oneof the bone anomalies associated with Neurofibromatosis Type1.

Standard X-rays show the different lesions found in this condition ranging from simpleconvex anterolateral bowing to true tibial discontinuity,with an image of resorption of the two ends of the fractureresponsible for significant loss of bone substance.Sometimes Cystic forms are also found, in which bowing of the Tibia (shinbone) appears atbetween 6 weeks and 1 year. The deformity gradually worsens until the bone finally breaks, causing atransverse fracture. In dysplastic forms, the bowing isvisible at birth and sometimes

pseudarthrosis may alreadybe present

Magnetic resonance imaging(MRI) will provide more detailed analysis of the bones, and the surrounding soft tissues.

Other tests that may be ordered at our clinic as given below:

Classification

Crawford classification

Frequently used today

This classification has theadvantage of being descriptive and identifying the different

stages as CPT progresses:

  • Type I: anterior bowing with an increase in cortical densityand a narrow medulla.
  • Type II: anterior bowing with narrow, sclerotic medulla.
  • Type III: anterior bowing associated with a cyst or signsof a prefracture.
  • Type IV: anterior bowing and a clear fracture with pseudarthrosisoften associating the tibia and fibula.

Prognostic factors

  • The association with Neurofibromatosis type 1 is a negativepredictive factor for bone union in CPT
  • Age is certainly an important factor with a better prognosiswhen the disease is not markedly progressive and thefracture occurs later. Surgery performed at 6 years age or later seems to affect the outcome favourably.
  • Previous failed surgery or post surgical infection from previous surgery adds to the difficulty.

The local factors are:

  • The site of pseudarthrosis: a lower location, in the inferior metaphysis, makes it difficult to control the distal fragment. The necessity of including the ankle and hindfoot in fixation may result in joint stiffness.
  • The type of pseudarthrosis also matters. Severe deformities with bone atrophy, extensive sclerotic lesions with a small diameter bone and significant shortening have a poor prognosis. Associated fibular involvement seems to worsen the prognosis.
  • Lower limb length discrepancies from the angulation and overlap of bone ends, or removal of bone from previous surgery, add to the problem.

Treatment:

At our clinic, the child is assessed thoroughly. The severity of the condition, associated Neurofibromatosis, previous surgery, and age are all considered.

If a child presents to us with angular deformity only without a fracture, initial treatment is brace application and gait training. This is especially of the child is less than 6 years of age.

If a child presents with a stiff non-union, we usually recommend brace application till age 6 years, and then operate.

A child presenting to us with a mobile non-union will need surgery irrespective of age, though we do and try to defer surgery to as late as we can, or stage our surgery.

The rationale for the delay is that children above 6 years with less active disease respond better to surgical treatment.

Treatment of CPT is surgical.The aims of surgical treatment are not only limited tounion of CPT. It must also restore satisfactory alignment ofthe leg to prevent the risk of recurrent fracture and limitleg length discrepancies while preserving articular function.

Surgical technique:

The patient is administered InjZolindronate 5 days before surgery in day care.

The Hemoglobin and general health is optimised before the operation.

The surgical technique consists of

  • Internal nail fixation ( intra-medullary nailing).

Titanium nails specially designed for children are applied after resection of the diseased bone ends. The bone is aligned and held together by this device.

If the bone size is large enough, telescoping nails are applied. These grow with the growth of bone and need not be changed for a long time.

  • Bone grafting

Bone is harvested from iliac crests or other sites and applied to the area to stimulate healing.

  • Ring Fixator

This is applied to compress the non unionsite , and carry out bone lengthening of the bone is shorter than the opposite side.

  • BMP application

BMP or Bone morphogenic Protein, is a stimulator of bone healing and this is applied to increase the chances of healing.

Once healing is complete, the external fixator is removed , and  a cast is applied. The cast is maintained for 4 weeks, after which a brace is given . the brace is worn till maturity – usually 12 years of age.

Physiotherapy after surgery is essential.

Regular follow up until age 12 -14 years is important.

Time sequence in a difficult case. (new folder 2)

The child was first diagnosed with CPT at age 2 years. He underwent first surgery at 3.9 years. This failed in 5 months. He underwent repeat surgeries at ages 4.5 years, 5 years, and 5.7 years. All surgeries resulted in failure. He came to the clinic and was advised surgery after age 6 years. In 9 months, his non-union had fully healed.

Age 2 years & 2.5

CPT diagnosed and it got worse by age 2.5 years.

Age 3.9 years

1st surgery done – bone realignment, pinning, bone grafting.

Age 4.5 years

Failed surgery, bone has not healed.

Age 4.6 years

Implants removed.

Age 4.9 years

Pseudoarthrosis visible clearly.

Age 5 years

Intramedullary implant, bone grafting and synthetic bone used as well.

Age 5.7 years

Failed Surgery, Implants removed at this point.

Age 6 years

Child attends our clinic with Non-union , deformation.

Age 6.1 years

Surgery done at our clinic.

Age 7.1 years

Fully healed in 9 months, X-rays at 1 year after surgery.

Congenital Pseudoarthrosis of Tibia is very difficult condition to treat. Outcomes can be poor with some cases requiring amputation.

At our clinic, we have favourable outcomes due to a combination of methods that we use for treatment. Also, we time surgery whenever possible in order to maximize the chances of healing.