Epidural Catheter With or Without Adductor Canal Nerve Block for Postoperative Analgesia Following Total Knee Arthroplasty

The purpose of this study is to further investigate the efficacy of adductor canal nerve blocks for pain management after total knee replacement. Specifically we are studying adductor canal nerve blocks in conjunction with epidural anesthesia, which is a combination that has not been extensively researched before. Our question is whether combining these modalities will enhance patient satisfaction after surgery and accelerate patients' readiness to discharge.

Knee replacement surgery has become increasingly more common in the United States with hundreds of thousands of surgeries performed yearly across the country. Despite that, there is no consensus "standard of care" for optimum pain control regimen after surgery. Pain management after TKA ranges from local tissue injections and patient controlled anesthesia to regional nerve blocks to neuraxial anesthesia. Although regional anesthesia has become more common and widespread, there are wide variations depending on practice setting (academic versus private), equipment available (adductor nerve blocks require ultrasound guidance), level of training of the anesthesiologists and patient selection, among other factors. Another part of the reason for the wide variations in practice is the lack of literature demonstrating clear effectiveness or superiority of one technique over another.

To date adductor canal nerve blocks have been mainly studied in comparison with femoral nerve blocks in terms of their efficacy in controlling pain and their ability to preserve motor function. Adductor canal nerve blocks have been shown in the literature to be an effective method for postoperative pain control in total knee replacement surgery. One of the unique benefits of this particular technique is that the adductor canal nerve block is primarily a sensory block, thereby controlling pain without impairing motor strength. This is useful for total knee replacement surgery as pain is controlled while quadriceps muscle strength is preserved. With well functioning muscles patients are able to fully participate in physical therapy with less strength impairment and reduced risk of falling.

It is our aim to investigate one multimodal approach that combines the strengths of two proven pain management techniques and thereby improve overall postoperative pain control and patient satisfaction. Our hope is to establish a protocol that is safe and effective for patient care.

Eligibility Criteria:
Inclusion Criteria:

* end stage degenerative joint disease
* enrolled for unilateral total knee arthroplasty at the University of Chicago
* age \< 85
* ability to understand and willingness to sign a written informed consent

Exclusion Criteria:

* age \> 85
* American Society of Anesthesiologists physical status \> 3
* known hypersensitivity to lidocaine, bupivacaine, ropivacaine or other local anesthetic agents
* Coagulopathy, specifically INR \> 1.5, Platelets \< 100, therapy with clopidogrel within 5 days prior to surgery, enoxaparin or fondaparinux within the last 24 hours prior to surgery, patients with anti-phospholipid syndrome requiring aggressive anticoagulation perioperatively
* History of alcohol or substance abuse (including strong opioids - morphine, oxycodone, methadone, fentanyl, ketobemidone), taking \> 50 mg morphine equivalent daily of opioids
* Pre-existing femoral neuropathy or radiculopathy
* Patients with poor ability to communicate