Intra-articular Analgesia

Options for peri-operative intra-articular (IA) analgesics are opioids or local anaesthetics. Over recent years concerns have been raised over the use of IA local anaesthetics.

Local anaesthetics

A series of cases of chondrolysis in young athletic people undergoing shoulder arthroscopy where 72-hour bupivacaine infusions were used brought into question the use of IA local anaesthetics (Petty and others 2004). In this report some role was also attributed to the use of radiofrequency thermal instruments.  After these procedures pain pumps were used to infuse bupivacaine into the joint. Chondrolysis, the rapid destruction of glenohumeral articular cartilage, has been associated with intra-articular pain pump use and confirmed to have chondrotoxicity in two animal study models (Busfield & Romero 2009). This finding led to further in vitro studies evaluating the influence of local anaesthetics on articular cartilage. 

Bupivacaine 0.5% demonstrated greater chondrotoxicity than 0.25% with significant chondrocyte damage occurring after 72 hours of bupivacaine 0.5% (Dragoo and others 2008). The effect of bupivacaine 0.125% on human or bovine chondrocytes was no different to that of 0.9% saline. 

The peri-operative analgesic effect of IA bupivacaine has been documented in dogs following elbow arthroscopy and cruciate surgery (Gurney and others 2012, Hoelzler and others 2005, Sammarco and others 1996). 

A British Journal of Anaesthesia editorial concluded that prolonged infusions of bupivacaine might have adverse clinical effects however single injection of low concentration bupivacaine appears to be safe (Webb & Ghosh, 2009). The in vitro effect of mepivacaine on equine chondrocytes demonstrated less chondrotoxicity than lidocaine or bupivacaine (Park and others 2011) and in dogs IA mepivacaine blunts the haemodynamic response to arthroscopic surgery (Dutton and others 2012).

Further to these concerns other authors have suggested alternative loco-regional techniques where possible. 

In summary the current literature is clear that high concentrations of bupivacaine over prolonged periods of time has a detrimental effect on chondrocytes. The in vivo effects of short term use, such as single injection pre or post arthroscopy is less clear. Experience of using the protocol given here is that the reaction to nociception intra-operatively is blunted and in the post operative period dogs are comfortable. There is no evidence of a clinically documentable adverse effect in the long term.

For elbow arthroscopy in dogs I use lidocaine 1ml/10kg IA before surgery starts, the infuse 1ml/10kg bupivacaine prior to portal closure. Buprenorphine is administered 4 hrs after premedication with dexmedetomidine/methadone and later that evening if required based on pain scoring. This protocol would be fine for elbow or stifle arthrotomy as well. For cruciate surgery the IA component of pain is only one part and techniques such as a femoral and sciatic nerve block provide a more complete blockade of nociception.

Opioids

Opioid binding sites have been demonstrated in canine synovial tissue using radio ligand studies in dogs with inflamed joints (Keates and others 1999). Studies by the same authors failed to demonstrate an effect of intra-articular (IA) morphine versus saline and concluded that further work was necessary examining dose. Two previous clinical studies in dogs undergoing surgery for cranial cruciate ligament repair reported beneficial effects of morphine 0.1mg/kg IA (Day and others 1995, Sammarco and others 1996,). When force plate analysis was used as an outcome measure in dogs following unilateral elbow arthroscopy limited beneficial effect to IA morphine was apparent (Gurney and others, 2012). 

Evidence from meta-analyses in humans show that single dose IA morphine in the human knee produces analgesia for up to 24 hours (Gupta and others 2001, Kalso and others 2002) has subsequently been reversed following consideration of confounding factors (Rosseland and others 2005) such as degree of inflammation, type of surgery, baseline pain and intensity of early post-operative pain. 

Studies in horses concluded that IA administration of morphine resulted in significantly less joint swelling and lower synovial fluid total protein and serum and synovial fluid SAA concentrations, compared to IV administration of morphine. In this study synovitis was induced experimentally and lameness and pain scores were not outcome measures. 

Bottom line, either IA morphine is ineffective as an analgesic in dogs, or we need more accurate outcome measures. 

References

Busfield, B. T., & Romero, D. M. (2009). Pain Pump Use After Shoulder Arthroscopy As a Cause of Glenohumeral Chondrolysis. Arthroscopy: the Journal of Arthroscopic & Related Surgery, 25(6), 647–652. http://doi.org/10.1016/j.arthro.2009.01.019

Dragoo, J. L., Braun, H. J., Kim, H. J., Phan, H. D., & Golish, S. R. (2012). The In Vitro Chondrotoxicity of Single-Dose Local Anesthetics. The American Journal of Sports Medicine, 40(4), 794–799. http://doi.org/10.1177/0363546511434571

Dutton, T. A. G., Gurney, M. A., & Bright, S. R. (2014). Intra-articular mepivacaine reduces interventional analgesia requirements during arthroscopic surgery in dogs. The Journal of Small Animal Practice, 55(8), 405–408. http://doi.org/10.1111/jsap.12232

Gupta, A., Bodin, L., Holmström, B., & Berggren, L. (2001). A systematic review of the peripheral analgesic effects of intraarticular morphine. Anesthesia & Analgesia, 93(3), 761–770.

Gurney, M. A., Rysnik, M., Comerford, E. J., Cripps, P. J., & Iff, I. (2012). Intra-articular morphine, bupivacaine or no treatment for postoperative analgesia following unilateral elbow joint arthroscopy. Journal of Small Animal Practice, 53(7), 387–392. http://doi.org/10.1111/j.1748-5827.2012.01222.x

Hoelzler, M. G., Harvey, R. C., Lidbetter, D. A., & Millis, D. L. (2005). Comparison of Perioperative Analgesic Protocols for Dogs Undergoing Tibial Plateau Leveling Osteotomy. Veterinary Surgery, 34(4), 337–344. http://doi.org/10.1111/j.1532-950X.2005.00052.x

Keates, H. L., Cramond, T., & Smith, M. T. (1999). Intraarticular and periarticular opioid binding in inflamed tissue in experimental canine arthritis. Anesthesia & Analgesia, 89(2), 409–415.

Park, J., Sutradhar, B. C., Hong, G., Choi, S. H., & Kim, G. (2011). Comparison of the cytotoxic effects of bupivacaine, lidocaine, and mepivacaine in equine articular chondrocytes. Veterinary Anaesthesia and Analgesia, 38(2), 127–133. http://doi.org/10.1111/j.1467-2995.2010.00590.x

Webb, S. T., & Ghosh, S. (2009). Intra-articular bupivacaine: potentially chondrotoxic? British Journal of Anaesthesia, 102(4), 439–441. http://doi.org/10.1093/bja/aep036