Intraoperative Liposomal Bupivacaine vs. Bupivacaine for Total Hip Replacement Pain Management

All surgeries were performed by the same orthopaedic surgeon. Two groups, one receiving
Exparel® (bupivacaine liposome injectable suspension) plus bupivacaine with epinephrine (LB
group) and the other receiving bupivacaine with epinephrine (Control group), will be compared
using post-operative pain scores, hospital length of stay, time to ambulation, falls,
narcotic use, and narcotic-related adverse effects. Aside from hospital length of stay, all
outcomes were recorded for up to 72 hours following surgery. An a priori power analysis was
performed to calculate the total number of patients that needed to be enrolled to achieve a
minimum 90% power, with the threshold of statistical significance set to 0.05. Based on a
previous study reporting a mean oral opioid consumption of 57.04mg ± 25.6 at 24 hours post
THR, a mean difference of 17.14mg was considered to be clinically significant. Thus, at least
26 patients were necessary in each group for an adequately powered assessment. The diagnosis
for osteoarthritis was determined by patient history, physical examination, and imaging
findings. Each patient received a thorough explanation of the protocol, and willing patients
signed an informed consent form. All patients underwent a personal preoperative education
program regarding pre, intra-, and post-procedural information including physical therapy,
expectations, discharge goals, home therapy, and pain management. After written consent was
collected, the form was sent to the hospital pharmacy for randomization. Envelopes were
randomized, sealed, numbered, and given to the pharmacy staff, ultimately dispensing the
envelopes to the nurse in the operating room in numerical order. The pharmacy documented the
required information, selected medication, and drug accountability forms according to the
contents of the envelopes.

A nurse delivered study drugs to the operating room in a sealed, non-descriptive envelope.
During the standard anterior approach procedure, an anesthesiologist administered fentanyl or
hydromorphone as needed for analgesia. The local anesthetics were administered after
reduction of the implants. Patients in the LB group received 20cc liposomal bupivacaine, 40cc
0.25% bupivacaine with epinephrine, and 20cc of normal saline. Each patient in the control
group received 60cc of 0.25% bupivacaine with epinephrine. Using a 20-gauge spinal needle,
the local anesthetics were injected using a deep tissue administration technique. Structures
innervated by the femoral nerve, superior gluteal nerve, or lateral femoral cutaneous nerve
were considered suitable for injection. Throughout administration, frequent aspirations were
performed to check for blood and minimize the risk of intravascular injection. The patients,
surgical team, and floor staff was blinded to the local anesthetic drugs given.

During hospitalization, patients were observed, evaluated and treated according to
postoperative protocols. Patients received opioids for pain management as needed, which was
routinely documented by hospital staff. Opioids included fentanyl, hydromorphone, oxycodone,
codeine, tramadol, morphine, and hydrocodone. All opioid dosages were converted into morphine
equivalent dosages for analysis. Each patient began physical therapy within the first 24
hours postoperatively. Patients were discharged when they were able to begin self-care, their
pain was controlled utilizing an oral regimen, and they were able to tolerate oral medication
intake.

Inclusion Criteria:

- Patients scheduled to undergo primary unilateral total hip replacement

- Patients diagnosed with hip osteoarthritis

- Patients failed to improve with conservative measures

- Patients willing and able to sign informed consent

Exclusion Criteria:

- Revision total hip replacement

- Bilateral total hip replacement

- Birmingham hip resurfacing

- Patients with hepatic/kidney disease

- Patients with a known allergy to bupivacaine or other local anesthetics