How Can We Best Balance Pain Control and Rehabilitation After Knee Replacement?

Total knee arthroplasty (TKA) is a common, painful surgical procedure that requires high-quality anesthesia and postoperative pain control to facilitate early rehabilitation. In the past, common barriers to early rehabilitation after TKA included pain, nausea, and dizziness, which often were related to basic analgesic methods that used opioid analgesics alone. The more recent use of multimodal analgesic techniques and peripheral regional anesthesia has allowed significant reduction in opioid requirements and improved pain control while reducing major side effects.1 Commonly used peripheral regional anesthesia techniques for TKA include femoral and sciatic nerve blocks (both single-injection and continuous techniques). These techniques provide profound pain control after major knee surgery but require careful titration to avoid impairment of motor function.2,3 In addition, their use requires extra training and resources and can provide a significant barrier to use in many institutions. More recently, periarticular infiltration and local infiltration analgesia (LIA) have demonstrated promise as simple, surgically administered methods of providing pain relief that do not impair motor function.4 Since the initial description, LIA has been investigated against various analgesic modalities (Table 1).5–26 Many of these studies have confirmed the analgesic benefit of LIA, but comparisons against methods such as femoral and/or sciatic nerve block have been less conclusive.5,19,27,28 Persisting concern about exacerbating motor weakness and impairment of rehabilitation has led many practitioners to evaluate more distal techniques such as blocks of the saphenous nerve in the adductor canal (adductor canal block [ACB])29 or tibial nerve block in the popliteal fossa.30 Studies on the ACB to date have demonstrated similar analgesic benefits without motor impairment compared with both single-injection and continuous femoral nerve block techniques.31–36 In 2013, Andersen et al.25 demonstrated that the addition of ACB to LIA led to better analgesia and earlier ambulation over LIA alone. For that reason, many practitioners are moving to the use of the ACB in preference to femoral nerve block to avoid motor impairment.Table 1.: Evidence for Local Infiltration Analgesia Alone or in Addition to Other Peripheral Nerve Block Techniques for Total Knee ArthroplastyIn this issue of Anesthesia & Analgesia, Sawhney et al.26 further our knowledge of the ACB by comparing, in a randomized and blinded fashion, the combination of ACB and local infiltration to either technique alone for patients having TKA. Although they found no difference in pain control with the addition of ACB to LIA for pain at rest, there was a significant reduction in pain in walking when the 2 techniques were used together. There was also a significant reduction in IV hydromorphone consumption in the combination group. Reassuringly, the addition of ACB did not cause any impairment in distance walked compared with LIA alone. Finally, the use of ACB alone (without LIA) led to poor pain control compared with the other 2 groups, suggesting that the use of ACB alone (without LIA) should be avoided. Disappointingly but not surprisingly, the beneficial effects of adding a single-shot ACB to LIA disappeared by postoperative day 2. The results of this study add to previous findings that demonstrate the analgesic benefits of the ACB when added to LIA. The lack of negative impact of the ACB on ability to ambulate should facilitate early recovery. Moreover, reduction in opioid consumption with the addition of ACB to LIA will lead to reduction in opioid-related adverse effects, further improving the ability to ambulate. Sawhney et al.26 advance our knowledge of the field by further demonstrating the analgesic benefit of the ACB when added to LIA alone for TKA. Use of the ACB should therefore be strongly considered for patients having TKA because of the benefits to pain control and reduction in opioid consumption without impact on rehabilitation. Although Sawhney et al.26 are to be commended for this advance in knowledge, further studies are required to continue to evaluate the place of ACB for early recovery after knee surgery. Few studies have evaluated ACB for knee procedures other than TKA.37–39 Because Sawhney et al.26 were unable to show any benefits of adding ACB to LIA beyond postoperative day 1, a continuous ACB technique should be the focus of further future investigations to examine whether benefit can be extended.36 The impact of these advanced peripheral nerve blocks on discharge readiness40 and ability to manage TKA patients at home needs further evaluation. Furthermore, the safety of additional multiple local anesthetic techniques with regard to local anesthetic toxicity needs to be examined. In summary, TKA is a painful procedure that requires good pain relief for optimal recovery. Sawhney et al.26 demonstrate that ACB is a useful addition to LIA alone for improving pain control and reducing opioid consumption without causing significant impact to early rehabilitation. This study adds to a growing body of literature demonstrating the analgesic benefits of ACB without impairing the all-important analgesic "balance" that is vital for successful recovery after TKA. DISCLOSURES Name: Colin J. L. McCartney, MBChB, PhD, FRCA, FRCPC. Contribution: This author conducted literature review and wrote the manuscript. Attestation: Colin J. L. McCartney approved the final manuscript. Name: Patrick Wong, MD, FRCPC. Contribution: This author conducted literature review and wrote the manuscript. Attestation: Patrick Wong approved the final manuscript. This manuscript was handled by: Terese T. Horlocker, MD.