Experimental research on repairing of bone defect by using hydroxyapatite combined with distraction osteogenesis technique

Abstract

Objective To investigate whether the combination of hydroxyapatite/tri-calcium phosphase (HA/TCP) and distraction osteogenesis technique would greatly reduce the time for the treatment of bone defects and enhance bone consolidation.Methods Osteotomy was made in the left tibia of all the 36 rabbits (age 20-24 weeks,body weight 2.2-2.8 kg),and a 1.0 cm length of the tibial shaft was removed below the tibiofibular junction.All rabbits were randomly divided into 3 groups,12 per group.Group A:The 1.0 cm defect gap was immediately reduced with the tibia shortened for 1.0 cm.Group B:The 1.0 cm defect gap was immediately filled with 1.0 cm restorable porous HA/TCP cylindrical block.Group C:The 1.0 cm defect gap was immediately reduced with the tibia shortened for 0.5 cm,and the remaining 0.5 cm defect gap was filled with 0.5 cm restorable porous HA/TCP cylindrical block.Then all the tibia was fixed with unilateral lengthener.For Group A and Group C,the lengthening started on the seventh day postoperatively,and lasted for 10 days and 5 days respectively.Group B didn't perform lengthening.All the rabbits wore terminated on the 37th days postoperatively.Serial radiographs were taken on the day of surgery,12,17,27 and 37 d postoperatively.The excised bone specimens were subject to micro-CT,mechanical testing,and histological examinations.Results Compared with the other two groups,the results in Group C were better in the terms of bone mineral content 454.44 ±89.98 mg,tissue mineral content 454.40±89.97 mg,maximum torque,maturity of regenerate bone,and the speed of bone consolidation and remodeling.Complete bone healing was achieved in the Group C within 37 days,but not in the Group A and B within 37 days.Conclusion The combination of HA/TCP and distraction osteogenesis technique can reduce the treatment time and promote bone consolidation compared with single treatment. Key words: Osteogenesis, distraction; Hydroxyapatites; Bones