Post-TKA Pain Reduced to Greater Extent with LA vs Regional Block

In this pooled meta-analysis, LIA provided better analgesia at rest in the immediate post-operative period when compared to RB, in addition to preserving quadriceps function.

Local infiltration of anesthesia (LIA) was shown to provide improved postoperative analgesia at rest when compared to regional nerve block (RB) and epidural analgesia (EA), according to findings from a meta-analysis published in Pain Physician. Additional benefits to utilizing local anesthesia (LA) include preservation of quadriceps function early in the postoperative period, which may have implications for improved functional recovery and early mobilization. 

Total knee arthroplasty (TKA) is an increasingly common operative procedure, especially for indications such as osteoarthritis. In this procedure, optimal early pain control is necessary to enable participation in appropriate physical therapy and to promote early ambulation to prevent deep vein thrombosis formation. 

Neuraxial analgesia methods, including insertion of epidural catheters for postoperative pain relief, are increasingly used in conjunction with TKA procedures. The use of neuraxial blockade, while effective, can also be associated with potentially unwanted side effects including hypotension, urinary retention, pruritis, and the risk of spinal infection. 

As a result, the use of peripheral nerve blocks (PNBs) including femoral nerve block, sciatic nerve block, obturator nerve block, and adductor canal block have been increasingly used to augment pain control in patients undergoing TKA. These nerve blocks, however, are associated with their own downsides, including unwanted prolonged local anesthetic effects on motor nerves that may prevent the orthopedic surgery teams from conducting a thorough neuromuscular postoperative examination following TKA.

The use of intraoperative LIA has advanced the utilization of multimodal pain control and has contributed to the progression of pain control in TKA procedures. To examine the clinical utility of LIA as compared to RB and neuraxial analgesia, Bin Hu, MD, of the Department of Orthopaedic Surgery, Wenzhou Medical University, Ningbo, People’s Republic of China, and colleagues collated studies for meta-analysis, including randomized controlled trials (RCTs) that compared LIA to RB where the primary outcome was defined as efficacy of postoperative pain control, amount of morphine consumption, time to functional recovery, complication profile, and length of hospitalization.

Researchers searched Embase, Medline, Cochrane Library, CINAHL, Web of Science, and Scopus for RCTs evaluating the efficacy and safety of LIA compared to RB for postoperative pain control following TKA. Nonrandomized trials, case reports, editorials, letters, commentaries, and comparative studies that did not state inclusion criteria were excluded for data analysis.

The meta-analysis found that when LIA was used for post-operative pain control post-TKA, a significantly lower numeric rating scale (NRS) score was obtained at rest, when compared to those patients who received RB (weighted mean difference [WMD]: -0.40 [-0.72, -0.07]; P = .02). Morphine consumption did not differ between groups  (WMD: -1.39 [-7.21, 4.44]; P = .64).

Patients who received LIA had increased ability to perform the straight leg test on post-operative day 1 as compared to those receiving TB (RR: 2.90 [2.15, 3.93]; P < .00001). These patients also demonstrated improved range of motion within 1 week of surgery as compared to those receiving RB (WMD: 4.33 [2.61, 6.05]; P < .00001). There were minor differences in inpatient hospitalization between patients receiving LIA and RB  (WMD: -0.25 [-0.49, -0.01]; P = .05).

Summary and Clinical Applicablity

In this pooled meta-analysis, LIA provided better analgesia at rest in the immediate post-operative period when compared to RB, in addition to preserving quadriceps function.

Limitations and Disclosures

A randomized clinical trial, adequately powered, would need to be performed to validate the results in this study.

No conflict-of-interest issues were declared by the study authors

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Hu B, Lin T, Yan SG, et al. Local Infiltration Analgesia Versus Regional Blockade for Postoperative Analgesia in Total Knee Arthroplasty: A Meta-analysis of Randomized Controlled Trials. Pain Physician. 2016;19(4):205-14.