Abstract
Background
Continuous post-operative infusion of local anaesthetic solutions has been implicated as the causative factor in many cases of chondrolysis. Recent in-vitro studies have shown that even a single exposure to local anaesthetic can cause apoptosis and mitochondrial dysfunction leading to chondrocyte death. Glucosamine has been shown to have a protective and reparative effect on articular cartilage.
Aims
To compare the effect of a single exposure of different local anaesthetic solutions on human articular cartilage and to investigate the protective and reparative effects of Glucosamine on articular cartilage exposed to 0.5% Bupivacaine.
Methods
Chondral explants (n=354) were obtained from femoral heads of hip fracture patients undergoing hemiarthroplasty. Each specimen was exposed to one of 8 test solutions for one hour. The specimens were then incubated in culture medium containing radio-labelled 35-sulphur for 16 hours. The uptake of 35-S by each specimen was measured to give an estimate of proteoglycan metabolism.
Test solutions
1. 1% Lidocaine 2. 2% Lidocaine 3. 0.25% Bupivacaine, 4. 0.5% Bupivacaine, 5. 0.5% Levo-Bupivacaine 6. Control solution of M199 culture medium. 7. To investigate its protective effect, 100 micrograms of Glucosamine was added along with 0.5% Bupivacaine 8. To investigate its reparative effect, Glucosamine was added after exposure to Bupivacaine for an hour.
Results
Compared to the control solution, the inhibition of proteoglycan metabolism was 64% with 1% Lidocaine(p< 0.001), 79% with 2% Lidocaine(p< 0.001), 61% with 0.25% Bupivacaine(p< 0.001), 85% with 0.5% Bupivacaine(p< 0.001) and 77% with 0.5% Levo-Bupivacaine(p< 0.001). Adding Glucosamine reduced Bupivacaine toxicity to 43%(p< 0.001). Glucosamine marginally repaired the damage caused by Bupivacaine, with inhibition of proteoglycan metabolism at 70%(p=0.004).
Conclusion
All local anaesthetic solutions were toxic to articular cartilage. The addition of Glucosamine to 0.5% Bupivacaine protected against its toxicity to articular cartilage.
