Pain Management After TKA: Comparison of Short- and Long-term Nerve Blocks

Overview

The purpose of this study is to determine if there is any significant difference between using a short-term ON-Q nerve block (which is applied prior to surgery and maintained in place until the medication in the initial balls have been fully used, usually 2-4 days) in comparison to a long-term ON-Q nerve block (which is applied prior to surgery and maintained in place up to seven days after surgery). This study will analyze patient reported levels of pain, range of motion, and narcotic use, as well as investigate whether blood loss, blood thinners, and hemoglobin/hematocrit blood levels influence patient pain levels. This study will compare patient-reported pain, range of motion and narcotic use in total knee arthroplasty patients who receive the short-term and long-term combination nerve block (saphenous and posterior of the adductor canal and wide-field posterior knee.

Post-operative pain remains one of the patient's greatest concerns after Total Knee Arthroplasty (TKA). Insufficient pain control can delay mobilization and inhibit rehabilitation efforts. Multimodal analgesia, including peripheral nerve block, is recommended for pain relief, and reaching an effective level of pain management, while minimizing opioid side effects, is vital to a patient's recovery and satisfaction of care delivered. The ON-Q pain relief system continually infuses local analgesia for effective pain relief. This is a prospective, randomized control trial designed to compare the effects of using the short-term and long-term combination ON-Q nerve blocks in connection with TKA surgery. The ON-Q nerve block and pump system provides slowly infused, continuous delivery of a local anesthetic to the surgical site and nerves. The use of concurrent saphenous and posterior knee nerve blocks with the ON-Q system has been adopted as standard procedure at our institute. The study does not involve an alteration to the typical procedures currently being employed. Ultrasound will ensure the accuracy of catheter placement by a regional anesthesiologist. All consecutive TKA patients who meet study criteria will be recruited for enrollment in the study prior to surgery. Pre-operatively, patients will be asked to complete health questionnaires, assessments to measure reported pain levels and location, and range of motion. Home medications will be reviewed, and hemoglobin/hematocrit blood levels will be recorded. Patients randomized to the long-term group will receive education on how to connect the ON-Q ball/pump to the catheter using a demonstration set to show understanding of the skill. Patients in the long-term group will also receive a 750mL ON-Q ball/pump filled with bupivacaine 0.125% for the select-a-flow saphenous catheter nerve block and a 400mL ON-Q ball/pump filled with bupivacaine 0.125% for the posterior fixed rate catheter nerve block to enable the nerve blocks to last up to the 7 days of treatment. Post-operatively, blood loss, inpatient hemoglobin/hematocrit levels, pain medications consumed and side effects, range of motion by Physical Therapy, and pain assessments will be recorded. After discharge, patients will receive daily phone calls up to day 7 post-op to collect reported pain scores, pain medications consumed and side effects, signs/symptoms of catheter site infection, and physical therapy or activity for that day. This information, as well as health questionnaires, will also be collected from both treatment groups at the 2-week and 6-week follow-up office visits. Data will be analyzed at the conclusion of the study.