Procaine and saline have similar effects on articular cartilage and synovium in rat knee

Ankay Yilbas A1, Akca B1, Buyukakkus B1, Bahador E2, Zeybek D2, Saricaoglu F1

1 Hacettepe University, Faculty of Medicine, Department of Anesthesiology and Reanimation, Ankara, Turkey
2 Hacettepe University, Faculty of Medicine, Department of Histology and Embryology, Ankara, Turkey

Background and Goal of The Study: Intraarticular local anesthetics are widely used for providing postoperative analgesia and decreasing the need for opioids (1). Procaine has proven positive effects in carpal tunnel syndrome and chondromalasia patella (2). In vitro studies also showed that procaine and its metabolite dietilaminoethanol (DEAE) decrease the formation of free oxygen radicals in leucocytes (3). However, the effects of procaine on articular cartilage and synovium has not been studied yet. The aim of this study was to evaluate the effects of intraarticular procaine injection on the articular cartilage and synovium.
Materials and Methods: Twenty adult Spraque-Dawley rats were enrolled in the study.After providing anesthesia and aseptic conditions; 0.25 ml 10% procaine was injected to the right knee joint and 0.25 ml normal saline (control group) was injected to the left knee joint. Knee joint samples were obtained from 4 rats in each group after appropriate euthanasia on days 1, 2, 7, 14 and 21. The histological sections of the articular regions and synovium were evaluated by two histologists and inflammatory changes were graded in a blinded manner. 
Results and Discussion: There were no significant differences of inflammation between procaine and saline groups in any time interval. Slight inflammatory infiltration due to injection was seen in both groups on the 1st day. Hemorrhage was more prominent on the 2nd day in procaine group but this difference was not statistically significant (p=0.057).
Conclusion(s): Injection of procaine seems safe to use intraarticularly in this in vivo study on rat knee cartilage. However, further studies investigating both the analgesic and histopathological effects of procaine on damaged articular cartilage and synovium models are needed.
References:
1. Piper SL, Kramer JD, Kim HT, Feeley BT. Effects of local anesthetics on articular cartilage. Am J Sports Med. 2011 Oct;39(10):2245-53.
2. Hauser RA, Sprague IS. Outcomes of prolotherapy in chondromalacia patella patients: improvements in pain level and function. Clin Med Insights Arthritis Musculoskelet Disord. 2014 Feb 17;7:13-20.
3. Dolganiuc A, Radu D, Olinescu A, Vrăbiescu A. Procain and diethylaminoethanol influence on the release of free oxygen radicals by polymorphonuclear leukocytes, in rabbits and humans. Roum Arch Microbiol Immunol. 1998 Jan-Mar;57(1):23-32.