Investigation of chondrotoxcicity caused by single intraarticular injection of bupivacaine and levobupivacaine in rats

Intraarticular local anaesthetic injection is a common procedure appied by anaesthetists and ortopedic surgeons. But, recent studies have shown that many of local anaethetics that used commonly as bupivakaine, lidocaine and ropivacaine have toxic effects on both human and animal chondrocyte in vivo and in vitro. Short term exposure with these local anaesthetics cause decrease in condrocyte metabolism, apopitosis in condrocyte, increase in necrosis and dense morfological cartilage degradation. In the animal model with the use of pain pomp, dense cartilage necrosis after continue local anaesthetic exposure has been shown. This study aims to investigate the short and long term effects of single dose intraarticular bupivakaine and levobupivakaine applied to knee joint. Sixty female Rattus Norvegicus rats which are 2-3 months aged and weighing 250 to 300 gr were used throughout the study. Rats were obtained from Akdeniz University Experimental Animal Unit. Two main groups were formed as bupivacaine and levobupivacaine group each contained 30 animals and then every group divided into three (n=10) as 1 week, 1 mounth and 6 mounths (It means 6 groups were formed each contains 10 animals). Under aseptic conditions and anaesthesia, 0,25 ml bupivakaine or levobupivacaine according to the group were injected to the right knee joints and 0,25 ml saline solution (0,9% NaCl) to the left. Animals were then returned to their cages. Animal were sacrified 1 week, 1 mounth or 6 mounths after the drug administration according to the study group and knee joints were resected. Cartilage tissue samples were washed with phosphate buffered saline solution (PBS) with three times and were prepared for the rutine procedure by light microscopy, ımmunohistochemical and TUNEL observations by parafine embedded blocks. Hematoxylin and eosin for condrocyte examination, toluidin blue for extracelluler matrix and TUNEL technique for the identifing the apopitototic cells were used. Dense of collagen 2 and agrecan in the extracellular matrix were detected by immunohistochemical method. According to the TUNEL results of bupivakaine rat group; there were more apopitotic cells in all three study groups (1 week, 1 mounth and 6 mounths) compared to the control group. Similarly, there were more apopitotic cells in the result of TUNEL of levobupivacaine study groups compared to the control. Besides, content of extracellular matrix in both bupivacaine and levobupivacain study groups were decreased compared to the control groups. In conclusion, we consider that intraarticular injection of bupivacaine and levobupivacaine is chondrotoxic and we think that risk of chondrotoxicity should be take into cosideration in the use of either as single dose or as long term infusion pomp