Evaluating the Role of PAI in TKA Patients Receiving Adductor Canal and IPACK Blocks

If patients are already receiving 2 nerve blocks – an adductor canal block (ACB) and an Infiltration between the Popliteal Artery and Capsule of the Knee (IPACK) block – during total knee arthroplasty (TKA), do they also need periarticular injection (PAI) of local anesthetics to relieve postoperative pain?

In other words, are there beneficial, additive pain-relieving properties of PAI that make it a necessary part of a multimodal pain management protocol for TKA patients?

Maybe – but also, maybe not.

In a study presented at the 47th Annual Regional Anesthesiology and Acute Pain Medicine Meeting of the American Society of Regional Anesthesia and Pain Medicine, PAI used in addition to ACB and IPACK did not appear to reduce pain during ambulation after TKA, nor did it reduce opioid use.

“Previous studies have shown that patients with a PAI do better when the nerve blocks are added to their pain management therapy,” said Jacques Ya Deau, MD, PhD, an anesthesiologist with Hospital for Special Surgery and the study’s senior author.

However, “we thought that it may not be necessary to do the PAI, given the theoretically nearly complete analgesia provided by the 2 nerve blocks. It’s best to avoid unnecessary procedures.”

Study Methods

For this triple-blinded, placebo-controlled, randomized clinical trial, the researchers enrolled 94 patients undergoing primary TKA and then randomized them to receiving PAI or a placebo. Patients in the PAI group received a deep injection consisting of:

  • 30 mL of bupivacaine 0.25%, with 1:200,000 epinephrine
  • 8 mg of morphine
  • 40 mg of methylprednisolone
  • 500 mg of cefazolin
  • Normal saline to bring total volume to 64 mL

They also received a superficial injection of 20 mL of bupivacaine, 0.25%.

Both groups received the standardized multimodal analgesia protocol of intraoperative sedation consisting of:

  • Midazolam and propofol
  • A mepivacaine spinal (60 mg)
  • ACB comprised of 15 mL bupivacaine 0.25% and 1 mg of preservative-free dexamethasone
  • IPACK block comprised of 25 mL bupivacaine 0.25% and 2 mg of preservative-free dexamethasone
  • Intraoperative ketamine (50 mg)
  • Ketorolac (15 mg)

Postsurgical pain relief included:

  • IV ketorolac, followed by oral meloxicam
  • IV then oral acetaminophen
  • 60 mg of oral duloxetine daily
  • 5 mg to10 mg of oral oxycodone by mouth every 4 hours as needed, with the opioid adjusted according to patient needs
  • IV hydromorphone in the PACU for breakthrough pain

Study Findings

The researchers reported on the numerical rating score (NRS) for pain and on patients’ opioid consumption. Their findings included to following:

  • No significant difference was observed in NRS pain score with ambulation between the PAI and placebo groups.
  • The ACB/IPACK/No PAI group was noninferior to the ACB/IPACK/PAI group in terms of NRS pain with movement on POD1.
  • No significant difference was observed for cumulative opioid consumption from the PACU to POD2 between the groups.

The researchers said that these results indicate that PAI may not provide a benefit in patients undergoing TKA with a multimodal pain relief plan that already includes ACB and IPACK blocks. “In the context of multimodal analgesia, the 2 nerve blocks provided excellent pain relief. There was no additional benefit from adding a PAI,” Dr. Ya Deau said.

They noted that their findings may not be generalizable to different types of orthopaedic surgeries or to patients with different underlying conditions or baseline characteristics.

Future Research

Dr. Ya Deau said that for future research, it will be important to investigate how clinicians can improve pain relief after the nerve blocks wear off a few days postoperatively.

“Currently, most TKA patients have excellent pain relief during the first few days. This is the acute pain phase, when otherwise pain would be most severe,” Dr. Ya Deau said. “Unfortunately, some of these patients have more pain than is desirable once discharged. We need to continue trying to improve pain management on days 3 to 14 after surgery.”


Lauzadis J, Padgett D, Westrich G, Gbaje E, Cushner F, Kahn RL, Lin Y, Goytizolo EA, Mayman DJ, Kim DH, Elysee KMJ, YaDeau JT. Does periarticular injection reduce pain after knee arthroplasty among patients receiving peripheral nerve blocks? (Poster 3070). Presented at the 47th Annual Regional Anesthesiology and Acute Pain Medicine Meeting of the American Society of Regional Anesthesia and Pain Medicine, March 31-April 2, 2022, Las Vegas, Nevada.

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