Systemic corticosteroids inhibit bone healing in a rabbit ulnar osteotomy model

Prolonged systemic administration of corticosteroids causes osteoporosis an d increased risk of fracture. Despite this well documented side effect of s ystemic corticosteroids, the effect of these compounds on fracture healing is not well defined. The goal of this study Has to test the hypothesis that systemic corticosteroid therapy adversely affects fracture healing in a ra bbit ulnar osteotomy model. Non-critical sized (1 mm) defects were created bilaterally in 18 adult female New Zealand White rabbits. Starting 2 months before operative intervention and continuing for 6 weeks during heating of the osteotomies, a subcutaneous dose of either sterile saline or prednison e (0.15 mg/kg) was administered daily. Serial radiographs of the forelimb w ere taken immediately postoperatively and weekly beginning the second week postoperatively. After killing at 6 weeks, only 3 of 20 limbs from animals treated with prednisone achieved radiographic union while 13 of 16 control limbs achieved union. The radiographic density of bone in the defect as wel l as callus size Here greater in the control limbs than in the limbs from p rednisone-treated animals. DEXA confirmed that the bone mineral content was lower in the ulnae of prednisone-treated rabbits both within the defect an d in adjacent ulnar bone. Mechanical data indicated that osteotomies from r abbits chronically treated with prednisone were weaker than in controls, In this rabbit ulnar osteotomy model, chronic prednisone treatment clearly in hibited bone healing.