Novel application of HA‐TCP biomaterials in distraction osteogenesis shortened the lengthening time and promoted bone consolidation

This study tested the hypothesis that use of biomaterials in distraction osteogenesis (DO) would reduce the treatment time and enhance bone formation quality. A 1.0‐cm tibial shaft was removed in the left tibia of 36 rabbits. Rabbits were randomly divided into three groups: group A, the defect gap was reduced with the tibia shortened for 1.0‐cm; group B, the defect gap was filled with 1.0‐cm restorable porous hydroxyapatite and Tri‐calcium phosphates cylindrical block (HA/TCP block, diameter is 0.5‐cm); group C, The 1.0‐cm defect gap was reduced 0.5 cm and the remaining 0.5‐cm defect gap was filled with the 0.5‐cm HA/TCP block. The tibia was then fixed with unilateral lengthener; for groups A and C; lengthening started 7 days after surgery at a rate of 1.0 mm/day, in two steps. Group A received lengthening for 10 days and group C for 5 days, there was no lengthening for group B. All animals were terminated at day 37 following surgery. The excised bone specimens were subject to microcomputed tomography (micro‐CT), mechanical testing, and histological examinations. Bone mineral density and content and tissue mineral density and content, as well as the mechanical properties of the regenerates were significantly higher in group C compared to groups A and B. Micro‐CT and histological examinations also confirmed that the regenerates in Group C had most advanced bone formation, consolidation, and remodeling compared to other groups. In conclusion, the combined use of biomaterials and DO technique can reduce the treatment time and enhance bone consolidation in bone defect management. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 477–482, 2009