Adductor Canal Block for Medial Compartment Knee Arthroplasty

Evaluation of Ultrasound-Guided Adductor Canal Blockade for Postoperative Analgesia Following Robotic Medial Unicompartmental Knee Replacement

This study will evaluate the affects of a single injection ultrasound-guided adductor canal block for patients undergoing robotic-assisted (MAKOplasty) medial UKA (unicompartmental knee arthroplasty). Specifically, this study will compare the adequacy of postoperative analgesia provided by the adductor canal block with that provided by single injection lumbar plexus blockade. The working hypothesis is that the analgesia provided by the adductor canal block will be equivalent to the analgesia provided by the lumbar plexus block. The primary outcome will be a comparison of verbal numerical pain scores at rest and with movement over the first 24 hours following nerve blockade.

Inclusion Criteria:

• Patients aged 18-85
• Undergoing unilateral robotic-assisted (MAKOplasty) medial compartment knee arthroplasty at Wake Forest University Baptist Medical Center.
• Must give written informed consent for anesthesia including subarachnoid blockade and peripheral nerve blockade of both the lumbar plexus and adductor canal.
• Must consent to the performance of a sham block at the site to which they are not randomized.
• Must also be reliable to give accurate verbal pain scores postoperatively.

Exclusion Criteria:

• Contraindication to adductor canal blockade or lumbar plexus blockade (including significant coagulation abnormalities)
• History of opioid addiction or current chronic pain therapy for pain other than at the surgical site that is being treated with high-dose opioids (extended release opioids or > 40mg oxycodone equivalents per day)
• Allergy to study medications
• Failure to adequately place either the adductor canal or lumbar plexus blocks.
• Patients who decline or have a contraindication to subarachnoid blockade will also be excluded from the study.
• Pregnancy.