Tibial pseudarthrosis is the name given to a fracture of the tibia (the larger of the two bones in the lower leg) that does not heal correctly. This incorrect bone healing is referred to by orthopedists as "nonunion." In most cases, the condition is associated with neurofibromatosis, a genetic disorder characterized by tumors (neurofibromas) that grow in the nervous system and under the skin.
Children with neurofibromatosis often have a bowing (bending) of the tibia that has a distinctive orientation - an anterolateral bow (toward the front) - that may lead to fracture and pseudarthrosis.
Because anterolateral bowing may be the first sign of neurofibromatosis, children with this deformity are usually followed by a pediatric neurologist and geneticist, as well as the orthopedist. In fact, according to Roger Widmann, MD, Chief of Pediatric Orthopedic Surgery at Hospital for Special Surgery, “Up to one-half of the children who are first seen by an orthopedist for anterolateral bowing of the tibia won’t have a diagnosis of neurofibromatosis. But by maturity, 80-90% of them will manifest the disease.”
Patients with an anterolateral bow without a fracture are treated with braces throughout childhood. “As the child gets older, the risk of fracture tends to go down,” Dr. Widmann says. The brace may be discarded when the child reaches maturity, but patients with tibial dysplasia (abnormal development of the tibia) may be monitored throughout life.
Surgical intervention is recommended for children with fractures and pseudarthrosis. The most common procedure involves use of a bone graft and intramedullary rod (placed inside the bone) to promote healing. In other cases, the patient may require removal of the abnormal portion of the bone and replacement with healthy, vascularized bone (with good blood flow) taken from the fibula (the smaller lower leg bone) in the patient’s other leg. With either one of these surgical approaches, the patient may also require leg lengthening to restore growth lost in the tibia.
“While none of these techniques are perfect, we can expect 90% of patients to heal using these methods,” Dr. Widmann says. “In all cases, we continue to follow the patient closely. In the small percentage of cases where union is not achieved, a second bone graft may be effective.”
Interview and summary by Nancy Novick