 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. 