In Vitro Exposure to 0.5% Bupivacaine Is Cytotoxic to Bovine Articular Chondrocytes Constance R. Chu, M.D., Nicholas J. Izzo, Ph.D., Nicole E. Papas, B.S., and Freddie H. Fu, M.D. Purpose: Intra-articular use of 0.5% bupivacaine is common in arthroscopic surgery. This study was conducted to test the hypotheses that (1) 0.5% bupivacaine is toxic to articular chondrocytes, and (2) the intact articular surface protects chondrocytes from the effects of short-term exposure to 0.5% bupivacaine. Methods: Freshly isolated bovine articular chondrocytes were prepared into alginate bead cultures and were treated with 0.5% bupivacaine solution or 0.9% saline for 15, 30 or 60 minutes, washed, and returned to growth media. Chondrocytes were recovered from alginate 1 hour, 1 day, and 1 week after bupivacaine exposure; they were fluorescently labeled to identify apoptotic and dead cells and were analyzed by flow cytometry. Twelve osteochondral cores were harvested from bovine knees. The superficial 1 mm of cartilage was removed from 6 cores (top-off ). Intact and top-off cores were submerged in 0.9% saline or 0.5% bupivacaine solution for 30 minutes and then maintained in chondrocyte growth media for 24 hours. Live-cell/dead-cell fluorescent imaging was assessed using confocal microscopy. Results: Greater than 99% chondrocyte death/apoptosis was observed in all bupivacaine-exposed alginate bead cultures compared with 20% cell death in saline-treated controls (P  .05). Osteochondral cores with intact surfaces treated with 0.5% bupivacaine showed 42% dead chondrocytes. When the articular surface was removed, 0.5% bupivacaine resulted in increased cell death, with 75% dead chondrocytes (P  .05). Conclusions: Results show that 0.5% bupivacaine solution is cytotoxic to bovine articular chondrocytes and articular cartilage in vitro after only 15 to 30 minutes’ exposure. The intact bovine articular surface has some chondroprotective effects. Clinical Relevance: Because healthy chondrocytes are impor- tant for maintenance of the cartilage matrix, chondrocyte loss may contribute to cartilage degener- ation. This study shows a cytotoxic effect of 0.5% bupivacaine solution on bovine articular chondrocytes in vitro. Although these results cannot be directly extrapolated to the clinical setting, the data suggest that caution should be exercised in the intra-articular use of 0.5% bupivacaine. Key Words: Articular cartilage—Cytotoxicity—Bupivacaine—Knee. I ntra-articular use of bupivacaine is common in ar- throscopic surgery. Bupivacaine is important as a local and intra-articular anesthetic agent. Surgeons may also inject bupivacaine solution with epinephrine into the intra-articular space to reduce intraoperative bleeding. Postprocedural injections of bupivacaine are frequently given as well. Recently, continuous intra- articular infusions of bupivacaine have been used for analgesia after shoulder surgery. Despite the common use of intra-articular bupiva- caine, its effects on articular cartilage are not well understood. Evidence suggests that bupivacaine may be harmful to articular cartilage and chondrocytes. Intra-articular injection of 0.5% bupivacaine into rab- bit knee joints caused increased inflammation of sy- novium and cartilage within 24 hours. 1 Reports of chondrolysis following continuous infusion of bupiv- acaine into the shoulder raise additional concerns that bupivacaine may have negative effects on articular cartilage (Freddie H. Fu, M.D., personal communica- tion, July 2005). Given that chondrocyte loss has been implicated in the development of chondrosis and osteoarthritis, 2,3 From the Cartilage Restoration Laboratory (C.R.C., N.J.I., N.E.P.); and Department of Orthopaedic Surgery (C.R.C., N.J.I., N.E.P., F.H.F.), University of Pittsburgh, Pittsburgh, Pennsylvania, U.S.A. Address correspondence and reprint requests to Constance R. Chu, M.D., Director, Cartilage Restoration Laboratory, 5200 Centre Ave, Suite 415, Pittsburgh, PA 15232, U.S.A. E-mail: chucr@upmc.edu © 2006 by the Arthroscopy Association of North America 0749-8063/06/2207-x630$32.00/0 doi:10.1016/j.arthro.2006.05.006 693 Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 22, No 7 (July), 2006: pp 693-699