Congenital pseudarthrosis (non-united fractures) of the tibia (shin bone) is a rare (1:190,000) and complex disorder. Because of the low number of cases worldwide, only major pediatric orthopedic centers have experience with this condition.
I have been performing corrective surgery for CPT for many years. Initially, fusing and healing the pseudarthrosis are necessary. Then, prevention of refracture is accomplished through increasing stability by inserting intramedullary rails or growing rods (Fassier-Duval telescopic rods; Pega Medical, Inc., Laval, Quebec, Canada) and applying bracing. I also correct many pretreated cases in which fusion has not been achieved that present with refracture and cases that require bone lengthening or correction of malalignment.
Pseudarthrosis refers to instability of a bone, which is usually found in the absence of healing after a fracture. With CPT, the tibia (shin bone) is weakened in an area (mostly in the middle or lower part) and can break without any trauma. The nature of the bone in this disorder renders it extremely difficult to heal this fracture. Even after healing, refracture is possible and must be prevented by applying different measures.
In cases of CPT, pseudarthrosis is not usually seen at birth but bending of the shin bone at the middle to lower third is often present. The pseudarthrosis usually becomes apparent only after walking begins and mostly around the age of 3 years. Treatment has traditionally consisted of preventing fracture and subsequent pseudarthrosis for as long as possible by consequent bracing of the leg. This is still a possibility for mild forms without malalignment.
When the bone bends more, and especially after fracture, additional changes occur to the ankle and soft tissues. The changes are exceedingly difficult to correct later on and, in some cases, can be only partially corrected. For this reason, I recommend early correction, even before appearance of the pseudarthrosis.
Intramedullary stabilization or plate fixation combined with bone grafting has a healing rate of approximately 50%. Microsurgical techniques that acquire bone from the healthy side show markedly better healing results. However, they are associated with complications in the area from which the bone has been obtained and risk of refracture and/or malalignment at the fusion site.
The most successful treatment to date starts with meticulous resection of the pseudarthrosis and the pseudarthrosis membrane. Afterward, the alignment is corrected and an intramedullary nail or growing rod (Fassier-Duval telescopic rod) is inserted into the bone.
Another important principle recognized by Dr. In Ho Choi and developed into a treatment regime by Dr. Dror Paley is to create a wide fusion/bone connection between the tibia and fibula (shin bone and calf bone) to prevent refracture.
Therefore, cancellous bone graft is harvested from the pelvis and mixed with a synthetic bone growth-stimulating factor (bone morphogenetic protein [BMP]). At the pseudarthrosis area, a sandwich is created of the BMP cancellous bone graft and periosteum from the pelvis. It induces healing and forms a fusion between the bones.
Fixation is achieved using an angle-stable plate or external fixation frame. An ankle-foot orthosis must be used until the end of growth to further protect the bones. Lengthening of the usually shortened tibia can be performed later on, in a separate surgery, or at the time of the initial surgery.