Objective: To determine the effect of extracorporeal shock wave (ESWT) on liposomal bupivacaine in a tibial-plateau-leveling osteotomy model.
Study design: In vitro study.
Sample population: Ten samples per group.
Methods: In addition to a control group (sham treatment), five treatment groups were defined as A, energy (E) 3 (0.22 mJ/mm2 ), 360 pulses per minute (p/m); B, E6 (0.29 mJ/mm2 ), 360 p/m; C, E8 (0.39 mJ/mm2 ), 360 p/m; D, E6, 480 p/m; E, E8 480 p/m. Two-milliliter aliquots of liposomal bupivacaine were placed in a gelatin chamber and treated with 1000 pulses according to group. All samples remained in the chamber for 170 seconds to reflect the longest treatment group. Free bupivacaine concentrations were determined after treatment with high-performance liquid chromatography.
Results: The median free bupivacaine concentration was reported as control, 1.90 mg/mL; A, 2.10 mg/mL; B, 2.03 mg/mL; C, 2.94 mg/mL; D, 2.71 mg/mL; E, 4.35 mg/mL. Groups C (P = .027), D (P = .034), and E (P = .002) were different from the control group. Groups C (P = .0025) and D (P = .0025) were different from group E. Additional intertreatment group differences were found.
Conclusion: Extracorporeal shock wave therapy caused a dose-dependent release of bupivacaine; however, there was no significant release of bupivacaine from liposomes when ESWT was applied at currently recommended therapeutic settings in this model.
Clinical significance: This in vitro study provides evidence that concurrent electrohydraulic ESWT and liposomal bupivacaine is likely safe at currently recommended settings, however, higher energy and pulse frequency settings should be avoided.