Innovations in motor-sparing regional anesthesia for total knee arthroplasty

Total knee arthroplasty (TKA) is a transformative surgical procedure that improves mobility and quality of life for patients with end-stage knee arthritis. However, the procedure is associated with significant postoperative pain, which can delay mobilization, prolong hospital stays, and increase healthcare costs. While traditional analgesic approaches often cause motor impairment, advancements in motor-sparing regional anesthesia techniques promise effective pain relief while maintaining muscle function. This review highlights motor-sparing options like local infiltration analgesia (LIA), adductor canal block (ACB), genicular nerve blocks, and iPACK (infiltration between popliteal artery and capsule of the knee) blocks, assessing their potential to enhance recovery after TKA.

Study objective and methods

The review aimed to explore contemporary motor-sparing regional anesthesia techniques for TKA, focusing on their ability to improve postoperative analgesia and functional recovery.

A systematic review of the literature was conducted, targeting randomized controlled trials, clinical audits, and meta-analyses. Techniques evaluated included LIA, ACB, genicular nerve blocks, and iPACK blocks.

Outcome measures included postoperative pain scores, opioid consumption, mobility, and side effects.

Key findings

1. Adductor canal block (ACB):

• • ACB provides effective analgesia for medial and anteromedial knee pain while preserving quadriceps strength.
  • Compared to femoral nerve blocks, ACB results in similar pain control with significantly less motor impairment.
  • Continuous ACB via catheter offers modest benefits over single-injection ACB, particularly in high-risk populations (e.g., older adults).

2. Genicular nerve blocks:

• • Targeting key sensory nerves around the knee, genicular nerve blocks reduce pain scores and opioid requirements.
  • These blocks are particularly effective in patients undergoing bilateral TKA, offering comparable analgesia to LIA with lower local anesthetic doses.

3. Local infiltration analgesia (LIA):

• • LIA involves periarticular injection of local anesthetic during surgery, providing immediate pain relief.
  • While effective, LIA’s benefits diminish when combined with other regional blocks like iPACK, as both target overlapping pain pathways.

4. iPACK block:

• • Designed to anesthetize the posterior knee capsule without affecting motor function.
  • iPACK is highly effective as a standalone technique but offers limited additional benefits when combined with LIA.

Conclusion

Motor-sparing regional anesthesia techniques like ACB, genicular nerve blocks, and iPACK blocks are pivotal in modern TKA recovery protocols. These approaches balance pain relief with preservation of motor function, enabling early mobilization and enhanced recovery. Among these, ACB remains the cornerstone due to its ease of use and consistent outcomes. However, individual patient needs and surgical contexts should guide block selection.

Future research

Future studies should investigate the long-term outcomes of these techniques, including their impact on chronic pain prevention and functional recovery. Additionally, research into combining multiple motor-sparing blocks to optimize pain relief while minimizing local anesthetic doses is essential. Finally, exploring personalized approaches for patients with preexisting conditions or opioid tolerance will further refine perioperative pain management strategies.

For more detailed information, refer to the full article in BJA.

White L, Kerr M, Thang C, Pawa A. Motor-sparing regional anaesthesia for total knee arthroplasty: a narrative and systematic literature review. Br J Anaesth. 2025;134(2):510-522.

Download the Nerve Blocks App HERE for in-depth insights on motor-sparing blocks for total knee arthroplasty. Prefer a physical copy? The bestselling NYSORA Nerve Blocks App is available in book format — an essential resource for mastering nerve blocks! And for a digital learning experience, check out the Nerve Blocks Manual Course on NYSORA’s LMS!