Distraction Osteogenesis of the Lower Extremity in Patients With Achondroplasia/Hypochondroplasia Treated With Transplantation of Culture-Expanded Bone Marrow Cells and Platelet-Rich Plasma

Background: Longer treatment period in distraction osteogenesis (DO) of the lower extremity leads to more frequent complications. We have developed a new technique of transplantation of culture-expanded bone marrow cells (BMCs) and platelet-rich plasma (PRP) during DO to accelerate new bone formation. To assess the efficacy of this cell therapy, retrospective comparative study was conducted between the bones treated with BMC and PRP and the bones treated without BMC and PRP during DO in patients with achondroplasia (ACH) and hypochondroplasia (HCH).

Methods: Fifty-six bones in 20 patients (ACH, 16; HCH, 4) that were lengthened in our hospital were divided into 2 groups. Twenty-four bones (femora, 12; tibiae, 12) in 11 patients (boys, 7; girls, 4) were treated with BMC and PRP transplantation (BMC-PRP group), whereas 32 bones (femora, 14; tibiae, 18) in 9 patients (boys, 3; girls, 6) did not undergo additional cell therapy (control group). The parameters, including the age at operation, the increase in length, and the healing index, were compared between the 2 groups. The clinical outcome was also compared between the femoral and tibial lengthenings.

Results: Bone marrow cells (average number, +/- SD, 3.2 +/- 1.37 x 10 cells) and PRP (average platelet concentration +/- SD, 2.36 +/- 0.57 x 10 cells/muL) were transplanted. Although there were no significant differences in the age at operation and the length gained between the 2 groups, the average healing index of the BMC-PRP group (27.1 +/- 6.89 d/cm) was significantly lower than that of the control group (36.2 +/- 10.4 d/cm) (P = 0.0005). The femoral lengthening showed significantly faster healing than did the tibial lengthening in the BMC-PRP group (P = 0.0092).

Conclusion: Transplantation of BMC and PRP shortened the treatment period by accelerating new bone regeneration during DO of the lower extremity in patients with ACH and HCH, especially in the femoral lengthening.