rhBMP-2 and Intramedullary Fixation in Congenital Pseudarthrosis of the Tibia.

BACKGROUND: In congenital pseudarthrosis of the tibia, use of intramedullary (IM) fixation and autogenous bone graft has long been the standard of care. This study was undertaken to determine whether the addition of rhBMP-2 to this treatment method further enhances healing potential.

METHODS: Twenty-one patients with congenital pseudarthrosis of the tibia were evaluated. Fifteen of these patients had neurofibromatosis type 1 (NF1). All had IM fixation and autogenous bone graft, followed by a BMP-soaked collagen sponge wrapped around both the fracture site and bone graft. A minimum 2 years' follow-up was required.

RESULTS: Follow-up averaged 7.2 years (range, 2.1 to 12.8 y). Sixteen of 21 tibias achieved bone union following the index surgery, at an average 6.6 months postoperatively. The 5 persistent nonunions occurred in NF1 patients. Further surgery was undertaken in these 5 NF1 patients, including the use of BMP. One of the 5 healed, 1 had persistent nonunion, and 3 eventually had amputation. Of the 16 patients who healed initially following the index surgery, 5 refractured (3 had NF1). Of these 5 patients, the IM fixation at the index surgery did not cross the ankle joint, and refracture occurred at the rod tip in 4. Three of these 5 patients healed following further surgery, 1 had persistent nonunion, and 1 had amputation. All of those with eventual amputation had NF1. No deleterious effects related to the use of BMP-2 were recognized in any patient.

CONCLUSIONS: The addition of rhBMP-2 appears to be helpful in shortening the time required to achieve fracture union in those who healed, but its use does not insure that healing will occur.

LEVEL OF EVIDENCE: Level IV-therapeutic, case series.