What is Congenital Tibial Pseudarthrosis?
In 1891, Paget was the first to describe a condition known as congenital pseudarthrosis of the tibia (CPT). This condition is recognized as a fracture in the tibia, the larger bone in the lower leg, not healing properly. This can occur out of nowhere or after minor injury, particularly if the affected segment of the bone was already misshapen. CPT is often linked with a higher chance of getting re-fractured.
CPT is typically viewed as one of the most common types of congenital pseudarthrosis, a condition where bones fail to heal after a fracture. Some common issues associated with CPT include unnatural forward or lateral bending of the bone, failure in the bone formation process during early life, and before fracture, the presence of small, fluid-filled sacs in the bone.
The exact cause of CPT is still a topic of debate, but it likely involves a reduced bone-healing capability in the affected tissue. Neurofibromatosis, a genetic disorder affecting nerve cell growth, is found in about 38 to 90% of CPT cases. Because of this, a multi-step strategy that includes genetic counseling is needed to screen for neurofibal disorders in all patients diagnosed with CPT.
The fibula, the smaller bone in the lower leg, shows abnormalities in about 60 to 90% of people with CPT. Several classification systems have been proposed to cover the diverse range of this condition. The severity of the condition determines the treatment options, which includes both surgical and non-surgical possibilities.
What Causes Congenital Tibial Pseudarthrosis?
The exact cause of this condition remains unclear, but there have been several theories suggested over the years:
1. In 1915, Gaenslen believed that it came down to genetic defects.
2. Inglis, in 1928, thought that damage caused by fetal compression and amniotic bands during pregnancy could be the cause.
3. That same year, Henderson suggested that it might be due to a lack of certain nutrients.
4. Duraiswami theorized in 1950 that hormonal disturbances could be the reason.
5. In 1952, Badgeley put forward the idea that issues with nerves and blood vessels early in the development of an embryo could lead to this condition.
Risk Factors and Frequency for Congenital Tibial Pseudarthrosis
Congenital pseudarthrosis of the tibia is a rare condition that occurs in about 1 in 150,000 births. This condition is often linked with neurofibromatosis-1, a disorder that is generally seen in 1 in 4,000 births. Between 40 to 80% of people with congenital pseudarthrosis of the tibia also have neurofibromatosis-1. However, less than 4% of people with neurofibromatosis-1 will have congenital pseudarthrosis of the tibia and a bowing of the tibia.
Signs and Symptoms of Congenital Tibial Pseudarthrosis
Congenital pseudarthrosis of the tibia is a condition that normally affects one leg and is noticed at birth or within the first few weeks. It results in a leg deformity where the tibia bone (the larger bone in the lower leg) curving towards the outside or appears to be disconnected. A secondary type of this condition can result in the child’s bones breaking easily, commonly when they start to walk. This condition can range from a simple curve in the tibia, more complex deformities of the leg bones, to fractures and false joints (pseudoarthrosis). The affected leg may also appear shorter due to the bowing of the tibia and slower growth rate.
If the condition is related to Neurofibromatosis Type 1 (NF-1), which is a hereditary disease affecting nerves and skin, a comprehensive skin and nervous system examination will also be carried out.
Testing for Congenital Tibial Pseudarthrosis
A normal X-ray should be the first test given to those suspected of having bone abnormalities. The X-ray can show bending in the bone, uneven lesions, and bone loss at the fracture ends.
In some cases, this bending can be seen early on, even before a person turns one year old. The inner part of the bone might also appear to be narrow, and the bend can increase over time and eventually lead to a crosswise fracture. In other complex cases, the bend might be present from birth, showing a thin tibia (or shinbone) resembling an hourglass, and the inner part of the bone could be partially or fully blocked.
The fibula (the smaller bone in your lower leg) is often affected in such situations. When an artificial joint forms in these cases, the ends of the bones might become thin and shrunken, or wide and enlarged. These various findings seen in X-rays form the basis for classifying the condition known as congenital pseudarthrosis of the tibia (a birth defect of the shinbone).
Magnetic resonance imaging (MRI) is increasingly being used because it gives a detailed understanding of soft tissue problems, particularly those in the periosteum (the layer that covers the bone) near the artificial joint. An MRI can also help visualize any issues with blood supply to the bones, which assists in deciding how much bone needs to be removed during surgery. Furthermore, an MRI is vital for better understanding how the condition affects the body.
Treatment Options for Congenital Tibial Pseudarthrosis
Congenital pseudarthrosis of the tibia, a condition that causes a false joint to form in the tibia bone, typically worsens as time progresses. That’s why managing it usually requires surgery to correct the worsening and deformation of this condition. When a child with this condition starts walking, use of a brace can help delay or control the associated deformation.
The main goal of surgical treatment is to achieve “union”, or healing of the bone. Surgery also helps restore good alignment to the limb, correct differences in limb length, and preserve normal joint function. Various kinds of surgery that can be performed are: intramedullary nailing with a bone graft, the Ilizarov technique, and vascularized fibular transfer.
Intramedullary nailing with a bone graft was first described in 1956 by Charnley. This surgery is based on a simple concept: remove the false joint and fix the bone with a special rod called an intramedullary implant. This implant gets added support from a large bone graft. This results in fixing the alignment of the limb, correction of deformity and regulates bone growth. There are different types of such implants, with the telescopic nail being a recent development.
The Ilizarov technique applies direct pressure on the false joint area with or without removing it, and it may or may not involve a bone graft. It’s most effective when the false joint is removed in the early stages. This technique also has the advantage of correcting any limb deformity after surgery and ensuring proper limb length.
Vascularized bone transfers, first described in 1978 by Judet and Gilbert, involve replacing the problematic tibia with healthy bone from another part of the body. The transferred bone tends to grow larger in response to mechanical stimulation over time. Typically, the bone is taken from the other fibula (the smaller bone in the lower leg), but it can also be taken from the same leg.
What else can Congenital Tibial Pseudarthrosis be?
When a child is diagnosed with a condition called congenital pseudarthrosis of the tibia, doctors typically consider several other similar conditions to ensure an accurate diagnosis. These conditions could include:
- Osteofibrous dysplasia of the long bones – a condition affecting the growth of bones.
- Congenital angulation of the tubular bones – a condition where the bones are angled at birth.
- Monostotic fibrous dysplasia – a condition where fibrous tissue develops in one bone instead of healthy bone tissue.
It’s crucial to identify the correct condition so that an appropriate and effective treatment plan can be put in place.
What to expect with Congenital Tibial Pseudarthrosis
The likelihood of a poor outcome in this condition often increases due to factors such as a major difference in limb length, weakening of the bone ends, narrowing of the bone’s inner core along with hardened bone tissue, and when the fibula (a leg bone) as well as curve in the tibia (shinbone) are involved.
Possible Complications When Diagnosed with Congenital Tibial Pseudarthrosis
Common problems related to this condition include repeated bone fractures, differences in limb length, a valgus (knock-kneed) deformity of the ankle, instability and stiffness of the ankle.
- Repeated bone fractures
- Differences in limb length
- Valgus (knock-kneed) deformity of the ankle
- Tibiotarsal instability
- Ankle stiffness
Preventing Congenital Tibial Pseudarthrosis
If a patient has a condition called congenital pseudarthrosis of the tibia, it’s crucial to get it checked and treated quickly. If left untreated, this condition can lead to serious long-term disabilities. The disease can cause severe deformities in the bone due to bent tibia (the large bone in your lower leg) and slower growth of the tibia. This can lead to abnormal fractures and a shortened leg. There are several surgical treatments available aimed at fixing the deformed bone, promoting bone healing, and restoring the length of the limb. It’s often necessary to involve a team of health professionals in the treatment process, especially because this disease is often associated with another condition called neurofibromatosis type 1.
