<qa>  What is the name of the study that is designed to characterize the PK profile of totalThis is a Phase 4, multicenter, open-label study designed to characterize the pharmacokinetic PK profile of total bupivacaine in approximately 15 adult subjects undergoing primary unilateral total knee arthroplasty TKA with bupivacaine hydrochloride HCl spinal nerve block SNB and EXPAREL local infiltration into the surgical site. 