33rd Annual Scientific Meeting proceedings

Introduction: The loss of large bone segments remains one of the most challenging problems in orthopedic surgery and considerable research continues with different results reported.

Objective: Propose an experimental model of critical bone segmental defect. 

Materials and Methods: Twelve New Zealand rabbits were divided into 2 groups (n=6 per group). A 7 mm ostectomy was performed in the mid-diaphysis of the radius of each rabbit with a high-speed drill. In Group-A, the defect was kept without any filling. In Group-B, the defect was filled with stored allogenous cortical bone graft and the ostectomy was stabilized with a 1.5 mm titanium locking plate and screws. Clinical and radiographic assessments were performed immediately post-operatively, 30, 60, 90, and 120 days after surgery. 

Results: Surgical procedures were fast and replicable (surgery time: Group-A: 10 minutes; Group-B: 20 minutes). After 120 days, rabbits in both groups had recovered well and walked without limping. Axial limb alignments did not change throughout the entire period. There were no complications. Radiographically at 120 days, all rabbits of Group-B showed complete bone union, while all rabbits in Group-A showed visible bone neoformation with incomplete bone union at the ostectomy site. 

Discussion/Conclusion: The bone defects were easy to make, with short surgical time and without complications. The ostectomy length used in this study can be considered as critical bone segmental defect as non-unions occurred in all rabbits of Group-A. Thus, it can be used as experimental model for this species.