Twenty-four 5-year-old female Merino sheep (mean body weight: 67 kg; range 57–79) were ovariectomized (OP1) and underwent 5.5 months of weekly corticosteroid injections (dexamethasone and dexamethasone-sodium-phosphate), adding to a calcium/phosphorus/vitamin D-deficient diet. Osteoporosis induction was documented by pQCT and micro-CT BMD (bone mineral density) as well as 3D histomorphometric analysis postoperatively of the sheep distal radius and spine. Non osteoporotic sheep served as controls. Induction of a VCF of the second lumbar vertebra was performed via a mini-lumbotomy surgical approach with a standardized manual compression mode (OP2).
PQCT analysis revealed osteoporosis of the distal radius with significantly reduced BMD values (0.19 g/cm3, range 0.13–0.22 vs. 0.27 g/cm3, range 0.23–0.32). Micro-CT documented significant lowering of BMD values for the second lumbar vertebrae (0.11 g/cm3, range 0.10–0.12) in comparison to the control group (0.14 g/cm3, range 0.12–0.17). An incomplete burst fracture type A3.1 was achieved in all cases and resulted in a significant decrease in body angle and vertebral height (KA 4.9°, range: 2–12; SI 4.5%, range: 2–12). With OP1, one minor complication (lesion of small bowel) occurred, while no complications occurred with OP2.
A suitable spinal fracture model for creation of VCFs in osteoporotic sheep was developed. The technique may promote the development of improved surgical solutions for VCF treatment in the experimental and clinical setting.