TREATMENT OF TIBIA DELAYED UNION BY BOVINE XENOGRAFT IN DOGS

Dehghani SN and Haghshenas M

Delayed bone union is a common complication encountered in tibial fracture healing. The purpose of this study was to compare conventional bone plates with xenograft plates made from bovine cortical bone. The long bones of a young bovine were cut into long pieces and shaped similar to conventional metal plates. They were then processed through oxidizing, degreasing, hydration, drying and sterilization by ethylene oxide. Bovine bone plates were used for fixation of tibia fracture in five dogs faced with delayed union/non union (group 1) and conventional metal plates in another five dogs of similar condition (group 2). They were monitored and evaluated clinically daily and radiographically every 20 days for 150 days. Radiographic assessment was performed on the basis of the scores given to various radiographic signs and a total score calculated for each radiograph. On the 80th post operative day, 60% of animals in the first group were able to put weight on the treated leg and walk normally while in the second group, 50% of the cases were able to stand and walk normally. Comparison of total radiographic score showed significant differences (P<0.05) between the two groups. Approximately 50% to 60% of the xenograft bone plate was resorbed on the 150th day post surgery while showing a complete healing at the fracture site. Periosteal and endosteal reaction was also evident during the healing process till the 80th day. It was concluded that xenograft bone plates can act as a supportive means of fixation, and its gradual resorption increases osteogenesis and osteoinduction, which hastens healing time without need of removal.