Tibial Dysplasia

Overview

Tibial dysplasia is abnormal development of the tibia, the larger of the two bones in the lower leg (the shin bone). The affected bone is often bowed, usually toward the front and side, and the bone in that area can be weak and fragile. In more severe cases the bone breaks and then fails to heal properly, a problem called a pseudarthrosis (false joint).

Tibial dysplasia is frequently associated with neurofibromatosis type 1 (NF1), and it is often noticed in infancy or early childhood when bowing of the lower leg is seen. Management is challenging and is handled by specialists in children's bone conditions, with the goals of keeping the bone aligned, preventing or treating fractures, and supporting normal use of the leg.

Symptoms

Tibial dysplasia is usually noticed early in life. Signs include:

• Bowing of the lower leg, often bending forward and to the side
• A difference in length or shape between the two legs
• A leg that appears abnormally angled or feels fragile
• A fracture of the shin, sometimes after only minor injury, that is slow to heal
• Limping or difficulty walking as the child grows

A new deformity, sudden inability to bear weight, or a leg that becomes painful and swollen after an injury should be evaluated promptly.

Causes

Tibial dysplasia results from abnormal development of the bone and surrounding tissue during growth.

• Neurofibromatosis type 1: A genetic condition strongly associated with tibial dysplasia and the related non-healing fractures.
• Other or unknown causes: The condition can occur without NF1, sometimes with no identifiable cause.

It is present from birth or develops in early childhood and is not caused by injury alone, although a weakened bone may fracture after minor trauma.

Risk Factors

• Neurofibromatosis type 1 (the main associated condition)
• A family history of NF1

Tibial dysplasia is uncommon, and most cases linked to NF1 are recognized in infancy or early childhood.

Diagnosis

Diagnosis is based on examination and imaging.

• Physical examination: Assessing the shape, angle, and stability of the lower leg.
• X-rays: The main test, showing the bowing, the quality of the bone, and any fracture or false joint.
• Evaluation for NF1: Checking for other features of neurofibromatosis, since the two are often linked.
• MRI or CT: Sometimes used for detailed planning before treatment.

Treatment

Treatment is individualized and managed by pediatric orthopedic specialists. The approach depends on the child's age, the degree of bowing, and whether a fracture or false joint is present.

• Protective bracing: A brace may be used to protect a bowed but unbroken bone and reduce the risk of fracture.
• Surgery: Often needed if the bone fractures and fails to heal, with the goal of getting the bone to unite and stay aligned; this can involve bone grafting, internal fixation, and other techniques.
• Treatment of leg length differences: Procedures to address differences in leg length as the child grows.
• Long-term follow-up: Because the bone can re-fracture, ongoing monitoring through childhood is important.

Treatment can be prolonged and may require more than one procedure.

Prevention

Tibial dysplasia cannot be prevented because it arises during bone development. The focus is on protecting the bone and detecting problems early:

• Protective bracing of a bowed bone to lower the chance of fracture, when advised
• Early specialist evaluation of any lower-leg bowing in a child
• Regular follow-up for children with neurofibromatosis type 1

When to See a Doctor

See a doctor if a child has bowing of the lower leg, a difference between the legs, or trouble walking. Seek prompt medical care for:

• A new bend or deformity in the lower leg
• Sudden inability to bear weight after an injury
• A painful, swollen lower leg following a fall or minor trauma

Related Topics

Frequently Asked Questions

References

1. Children's Tumor Foundation. Neurofibromatosis and Bone.
2. MedlinePlus, U.S. National Library of Medicine. Neurofibromatosis.
3. American Academy of Orthopaedic Surgeons (AAOS). Congenital Conditions of the Lower Limb.
4. National Institute of Neurological Disorders and Stroke (NINDS). Neurofibromatosis.