Retrospective analysis of post-operative adductor canal block with epidural anesthesia for total knee replacement
Malik M, Alsaden MR. Retrospective analysis of post-operative adductor canal block with epidural anesthesia for total knee replacement. Regional Anesthesia and Pain Medicine 2017; 42(6).
Regional Anesthesia and Pain Medicine
Introduction Regional anesthesia for total knee joint replacement (TKR) includes spinal, epidural, combined-spinal epidural or peripheral nerve blocks. Current practice at our academic institution include epidural placement for primary surgical anesthesia with an adductor canal block (ACB) for postoperative pain control. This was felt to provide good intraoperative anesthesia with early mobility and participation in physical therapy (PT). Materials and methods (NA for case report) Patient selection was determined by joint anesthesia and surgical evaluation after an IRB waiver was obtained for epidural placement and ACB. Patients who had contraindications to regional anesthesia or where surgical preference was for general anesthesia (GA), were excluded. After epidural placement, the initial test dose was immediately followed by 5ml of 2% Lidocaine. Once an adequate sensory level was determined, the patient received a further 5ml of 2% Lidocaine in the preoperative holding area, with subsequent 5ml aliquots given en route and upon arrival to the OR. After surgery had commenced, the epidural was re-dosed every 60-75 minutes with further 5ml aliquots of 2% Lidocaine as deemed necessary by the anesthesia provider. In the post anesthesia care unit (PACU), patients were reassessed for epidural discontinuation and removal with placement of an adductor canal block (15-20ml of 0.375% bupivacaine) as part of the multimodal analgesia protocol. Retrospective chart review for all TKR's over the 8-month period following initiation of the protocol was performed. Primary measured outcomes included length of stay (LOS) and opioid consumption [morphine equivalents (MED)] at 12, 18 and 24 hours post-operatively. Secondary outcomes included pain scores, mobility and active assisted range of motion (AAROM) for knee flexion as part of the criterion for discharge at the initial postoperative PT visit. Results/Case report There were 73 cases of TKR of which 27 received epidural anesthesia as primary anesthetic with a postoperative ACB. 17 received spinal with ACB, 22 GA with ACB and the remaining received GA without ACB. Comparing epidural to no epidural we found: LOS 0.7 days shorter [95% Confidence Interval (CI) of -1.1 to -0.29], total opioid consumption in the first 24hrs 15.4mg MEDs higher [95% CI 2.6-29mg], pain score 1.2 VAS lower [95% CI -3.0 - 0.75], mobility at initial postop PT visit 19 feet shorter [95% CI -25ft to -2.5 ft], AAROM of knee flexion 32 degrees higher [95% CI 17° - 48°]. Discussion The group who received epidural anesthesia with a postoperative ACB had a significantly shorter LOS (0.7 days less), greater AAROM for knee flexion on the initial postoperative PT visit (30° more), but with greater opioid consumption in the first 24hours (15mg MEDs). The increased opioid consumption was most likely due to the ACB wearing off after 12-18 hours postoperatively. Adductor canal block is a relatively new block that provides an almost pure sensory blockade to the knee region. There is accumulating evidence that ACB results in less reduction in quadriceps muscle strength compared with femoral nerve block, while still providing a comparable analgesic effect in the setting of multimodal analgesia. Postoperative ACB with epidural anesthesia is recommended as a potential anesthetic management technique for TKR.