Interscalene Single Shot With Plain Bupivacaine Versus Liposomal Bupivacaine for Arthroscopic Shoulder Surgery

Background:

The current standard of care for patients at the investigators' institution is to perform an
interscalene peripheral nerve block for patients receiving arthroscopic shoulder surgery
surgery as it is an effective opioid-free alternative for post-operative pain control. The
investigators in the past perform both single shot injections and place catheter based on
patient and surgical preferences. Catheters have shown to have extended benefit throughout
the perioperative period, including lower pain scores, reduced analgesics and improved sleep.
However, the negatives of catheters include the placement of a foreign body, increased time
to perform the procedure, interference in surgical field and increased cost of catheter
equipment and local anesthetic pump and premature catheter dislodgement. Therefore, pros and
cons of deciding between placing a single shot injecting versus catheter has to be considered
individually for each case.

Liposomal bupivacaine due to its liposomal outer layers, releases bupivacaine over a longer
period of time than plain bupivacaine. A pharmacokinetic study showed the terminal half-life
of bupivacaine to be 131 ± 58 minutes versus 1294 ± 860 minutes for liposomal bupivacaine.

In a recent study comparing liposomal bupivacaine to placebo for interscalene peripheral
nerve blocks, patients receiving liposomal bupivacaine had significantly lower pain scores
over 48 hours and received less opioid over 72 hours[6]. Therefore, if a single shot
injection with liposomal bupivacaine can provide longer pain relief than plain bupivacaine,
it makes the decision to perform single shot interscalene peripheral nerve blocks easier.

Study Objectives The investigators would like to study whether an interscalene peripheral
block injection with liposomal bupivacaine provides superior pain control compared to an
interscalene single shot with plain bupivacaine. The investigators will be looking at average
daily pain scores, highest daily visual analog scale (VAS) pain scores at rest and with
movement, total daily opioid consumption from immediately post-operative to 7 days
post-operative, and functionality with physical therapy. The investigators will also plan to
follow these patients 6 month and 12 months post-operative to determine whether there is any
difference in incidence of persistent post-operative pain.

Inclusion Criteria:

- medically optimized patients that will undergo an elective surgery for arthroscopic
shoulder surgery

Exclusion Criteria:

- under 18 years pregnant or breast-feeding, non-English speaking, have renal or hepatic
dysfunction, history of chronic opioid use, receiving worker's compensation, smoker,
receiving capsular release, respiratory compromise or BMI < 18 or > 35 or allergy to
local anesthetics or opioids