Jinuk Park

Comparison of the cytotoxic effects of bupivacaine, lidocaine, and mepivacaine in equine articular chondrocytes

OBJECTIVE To compare the chondrotoxicity of bupivacaine, lidocaine, and mepivacaine in equine articular chondrocytes in vitro. STUDY DESIGN Prospective, experimental study. STUDY MATERIAL Equine articular chondrocytes. METHODS Primary cultured equine chondrocytes were exposed to 0.5% bupivacaine, 2% lidocaine, or 2% mepivacaine for 30 or 60 minutes. After treatment, cell viability was evaluated by trypan blue exclusion and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay in a dose dependent manner. Apoptosis and necrosis of chondrocytes were analyzed with the double staining of Hoechst 33258 and propidium iodide using fluorescence microscopy, and the results were confirmed using flow cytometry. RESULTS After 30-minute exposure, trypan blue exclusion assay revealed that cell viability of 0.5% bupivacaine group was 28.73±8.44%, and those of 2% lidocaine and 2% mepivacaine were 66.85±6.03% and 86.27±2.00%, respectively. The viability of chondrocytes after saline treatment was 95.95±2.75%. The results of MTT assay and fluorescence microscopy had similar tendency with trypan blue assay. Each result showed that bupivacaine was the most toxic of the three local anaesthetics. Mepivacaine was less toxic than lidocaine. The results of the viability test suggest that bupivacaine and lidocaine exhibit a marked chondrotoxicity, and that this is mainly due to necrosis rather than apoptosis. CONCLUSIONS AND CLINICAL RELEVANCE Bupivacaine may induce detrimental chondrotoxicity when administered intra-articularly, especially in patients with joint disease, and we suggest that it should be used cautiously in equine practice. Mepivacaine may be an alternative to both bupivacaine and lidocaine.

Traumatic and Non-traumatic Osteonecrosis in the Femoral Head of a Rabbit Model.

Osteonecrosis of the femoral head is an idiopathic, debilitating and progressive disease. A number of traumatic or non-traumatic animal models have been reported for research on osteonecrosis. This study was performed to compare the efficacy of femoral head osteonecrosis in rabbits by traumatic and non-traumatic methods. Twenty-seven New Zealand White rabbits were divided into three experimental groups, nine heads each. Two groups were surgically induced into osteonecrosis; a steel cerclage wire was ligated tightly around the neck of the right femoral head (Group W), and the femoral neck was tied with a cerclage wire in the same way as in the W group, and burned by attachment of an electrode tip to the wire and then the wire was removed (Group B). The other group was induced into osteonecrosis with a single intra-muscular injection of 20 mg/kg methyl-prednisolone acetate single injection (Group M). In the control group, the left femoral head of animals in group W and B was used. After two weeks, rabbits were sacrificed and the femoral head and neck were collected. Osteonecrosis of the femoral head was evaluated by radiography, histology and immunohistology methods. Osteonecrosis lesions in the femoral head were identified in traumatic models of groups W and B. Cartilage degeneration in the superficial layer and TUNEL positive cells in the femoral head were detected more in Group B than in Group W. These findings revealed that short-term induced osteonecrosis of the femoral head was effectively achieved by cautery around the femoral neck.