Minimum effective volume of ropivacaine for ultrasound-guided adductor canal + IPACK block in total knee arthroplasty: A double-blind, randomized dose-finding trial

Efficacy of adding infiltration between the popliteal artery and the capsule of the posterior knee (IPACK) to adductor canal block and local infiltration analgesia in total knee arthroplasty: A retrospective cohort study

OBJECTIVE

Local infiltration analgesia (LIA), adductor canal block (ACB), and infiltration between the popliteal artery and the capsule of the posterior knee (IPACK) are popular multimodal analgesia techniques used during total knee arthroplasty (TKA). This study aimed to explore the efficacy of adding the IPACK technique to ACB and LIA in patients undergoing TKA.

METHODS

In this retrospective cohort study, patients who underwent primary unilateral TKA were divided into two groups based on their date of admission. Sixty-three patients underwent IPACK, ACB and LIA (IPACK group) during surgery, while 60 patients underwent ACB and LIA (control group). The primary outcome was the postoperative administration of morphine hydrochloride as a rescue analgesic. Secondary outcomes included time to first rescue analgesia, postoperative pain assessed using the visual analog scale (VAS), functional recovery assessed by knee range of motion and ambulation distance, time until hospital discharge, and complication rates.

RESULTS

The two groups were similar in average postoperative 0-to-24-h morphine consumption (11.8 mg for the control group vs 12.7 mg for the IPACK group, p = .428) and average total morphine consumption (18.2 mg vs 18.0 mg, p = .983) during hospitalization. There were also no significant differences in the secondary outcomes.

CONCLUSIONS

The addition of IPACK to ACB and LIA did not provide any clinical analgesic benefits. Orthopedic surgeons and anesthesiologists are justified in using ACB and LIA without IPACK for TKA.

Posteromedial Periarticular Injection in Total Knee Arthroplasty: A Cadaveric Study

Achieving optimal pain control in total knee arthroplasty has improved with the use of regional anesthesia and periarticular injections (PAIs). When performing a PAI, the relative location of the anesthetic spread is not well defined in comparison with an adductor canal block (ACB). In this study, our aim was to evaluate the location of posteromedial PAI spread compared with a surgeon administered ACB. One PAI and one surgeon-administered ACB were performed in the contralateral limbs of four human cadavers. The injectate was composed of methylene blue dye to visually inspect the dye spread from the tip of the needle. Dissections were performed on each cadaver to quantify the dye spread from the tip of the needle and compare the location of the dye spread. Dye spread location was characterized as either entering the adductor canal or including the posterior capsule. The mean distance of dye spread from the needle tip to the proximal most aspect of the dyed tissue was 10.125 cm in the ACB group compared with 6.5 cm in the posteromedial PAI group. In the ACB group, 4 of 4 injections were present in the adductor canal block group compared with 3 of 4 in the posteromedial PAI group. The posteromedial PAI group also had 3 of 4 injections involve the area around the posterior capsule compared with 0 of 4 in the ACB group. Posteromedial PAI appears to provide local delivery to both the adductor canal and the posterior capsule. Intraoperative, surgeon-administered ACB reliably delivers injectate to the adductor canal only but may allow for more proximal dye spread. Posteromedial PAI may provide a benefit in delivering injectate to the posterior capsule in addition to the ACB. Additional clinical studies are necessary to determine the clinical effects of this finding.