Establishment of a canine model of lunate ischemic necrosis by liquid nitrogen freezing and devascularization

Abstract

Objective To establish a canine model for the study of ischemic necrosis of the lunate.Methods Twelve adult canines were used.The lunate was exposed and stripped off its peripheral tissues and then frozen by liquid nitrogen.X-ray,CT and MRI images of the lunate were acquired at 3,6 and 12 weeks to track the dynamic changes.Lunate was harvested at these time points for gross and histology examination to evaluate the necrosis of lunate and subsequent repairing reaction.Results At 3 weeks there were no significant changes on X-ray and CT.Diffused sporadic enhanced signals were seen on T2 weighted MRI images.At 6 weeks X-ray and CT scans were still insignificant.However T2 weighted MRI showed more abnormality with areas of enhanced signals.At 12 weeks heterogenous bone density,irregularity and compression deformity of the carpal bone were seen on X-ray.CT scans showed large areas of low density loci,while MRI showed large areas of enhanced signals on T2 weighted images.There were significant changes in gross and microscopic manifestation of the lunate.Large area of whitish necrotic bone and decaying of cartilage surface were seen.Light microscopic sections revealed decreased bone density in the trabeculum and loci of bone collapse.Conclusion Liquid nitrogen freezing and devascularzation of the lunate is a successful and reliable method to establish a canine model of Kienbock's disease. Key words: Carpal bones; Osteonecrosis; Animal model; Liquid nitrogen freezing