Background: Pain and decreased mobility are significant problems that occur after a total knee replacement (TKR) that can hinder a patient's rehabilitation if not addressed. Orthopaedic surgeon at Georgetown University Hospital, Dr. Brian Evans, has recently started to use the ON-Q PainBuster (also known as the "Pain Ball") in addition to epidural analgesia as a new method to help reduce post-operative pain. This proposed research study has numerous implications for nursing practice.

Purpose: The purpose of this retrospective study is to determine if the new therapy of using the ON-Q Pain Ball in addition to epidural analgesia is more effective in reducing post-operative pain in TKR patients (secondary to osteoarthritis) than using epidural analgesia alone. A secondary objective is to discover if as a result of decreased pain, patients have enhanced functional mobility and decreased length of stay.

Methods: During this non-experimental research study, a retrospective chart review will be conducted on a random sample of unilateral TKR patients (secondary to osteoarthritis). Subjects will be both genders between the ages of 30-90 years old. Pain scores, mobility, and length of stay will be compared between the two groups, those who only had an epidural PCA compared to those who had an epidural PCA and an ON-Q Pain Ball after surgery. Pain will be evaluated by comparing levels based on the Numeric Rating Score (NRS). Mobility will be evaluated by comparing the degree of flexion achieved on the CPM machine and the daily measurement of the goniometer.