Postoperative Pain Control for Total Knee Arthroplasty: Continuous Femoral Nerve Block Versus Intravenous Patient Controlled Analgesia


avatar Rui Min Lee 1 , * , avatar John Boon Lim Tey 1 , avatar Nicholas Hai Liang Chua 1

Department of Anesthesiology, Intensive Care and Pain Medicine, Tan Tock Seng Hospital, Singapore

how to cite: Lee R M, Tey J B L, Chua N H L. Postoperative Pain Control for Total Knee Arthroplasty: Continuous Femoral Nerve Block Versus Intravenous Patient Controlled Analgesia. Anesth Pain Med. 2012;1(4): 239-242. doi: 10.5812/aapm.3404.



Pain after total knee arthroplasty is severe and impacts functional recovery.


We performed a retrospective study, comparing conventional patient control analgesia (PCA) modalities versus continuous femoral nerve blockade (CFNB) for 1582 post-TKA (total knee arthroplasty) patients.

Patients and Methods:

Using our electronic acute pain service (APS) database, we reviewed the data of 579 patients who had received CFNBs compared with 1003 patients with intravenous PCA over 4 years.


Our results show that the incidence of a severe pain episode was higher in the PCA compared with the CFNB group. Lower pain scores were observed in the CFNB group compared with the PCA group from postoperative day (POD) 1 to 3, primarily due to lower rest pain scores in the CFNB group.


Our study shows that there is improvement in pain scores, at rest and on movement, as well as a reduction in incidence of severe pain, in patients who receive CFNB versus those who receive intravenous PCA.

1. Background

Severe postoperative pain is a major complaint in patients who have undergone total knee arthroplasty (TKA). In addition, post-TKA pain directly impacts postoperative physiotherapy and mobilization, which can result in stiffness and poor joint function (13). Post-TKA pain peaks up to 48 hours after surgery (4).

Effective postoperative pain control is important, especially with the initiation of physiotherapy and early ambulation, which hastens recovery and reduces hospital length of stay (5). The risk of postoperative complications, such as venous thromboembolism and nosocomial infections (6), has also been shown to decrease with early mobilization.

Pain control modalities for post-TKA include intravenous patient-controlled analgesia (PCA), peripheral nerve blockade, and continuous epidural analgesic techniques. All methods have been shown to be efficacious in relieving postoperative pain. However, conventional techniques that use intravenous PCA with morphine and fentanyl are associated with side effects, such as respiratory depression, sedation, pruritus, nausea and vomiting, hypotension, constipation, and urinary retention (7); epidural analgesia is associated with hypotension and bilateral motor blockade if local anesthetics are used (8, 9).

2. Objectives

We performed a retrospective study, comparing conventional PCA modalities versus continuous femoral nerve blockade (CFNB) for 1582 post-TKA patients.

5. Discussion

Our study shows that there is improvement in pain scores, at rest and on movement, as well as a reduction in the incidence of severe pain in patients who receive CFNB versus those who receive intravenous PCA. There were no documented adverse events in the CFNB group, whereas an incident of hypotension and respiratory depression was noted in the PCA group. We did not record common side effects, such as pruritus, nausea, and vomiting. To our knowledge, this is the largest single-center retrospective study of CFNB alone versus PCA.

Severe pain after total knee arthroplasty has been shown to impact functional recovery (10). Various studies have demonstrated the effectiveness of femoral nerve blocks in reducing pain post-total knee arthroplasty compared with intravenous PCA (3, 7, 8, 1117). A systematic review of 112 studies between 1996 and 2005 by the PROSPECT working group supports the use of femoral nerve blocks for postoperative analgesia for primary TKA, based on the reduction in pain scores and supplemental analgesia (10). Of the 112 studies, 5 investigated the use of continuous infusion femoral nerve block versus placebo (8, 1821), all of which noted reduced pain scores at rest and with motion at 24 and 48 hours with CFNB.

Similarly, a recent meta-analysis by Paul et al. (6) found that single-shot and continuous FNB was superior (lower opioid consumption) to PCA alone. In particular, continuous FNB with intravenous PCA was clearly superior to PCA alone with regard to reduced morphine consumption at 24 and 48 hours, pain scores, and nausea. Currently, there is a paucity of evidence to support the use of single-shot femoral nerve block as opposed to continuous nerve block technique. In 2 studies (20, 22), however, the authors showed significant improvements in analgesic use at rest and on movement, as well as opioid-sparing benefits, with single shot nerve blocks.

Because our report was a retrospective case review, there are inherent limitations. The data were obtained from an electronic database; thus, details, such as the method of insertion of the femoral nerve catheter, mode of anesthesia, and surgical technique, were unavailable. For future studies, it might be useful to perform continuous FNB, which allows one to control the concentration of the local anesthetic dose, type of local anesthetic, and infusion regimen, which preserves the quadriceps function better, resulting in earlier mobilization (23).

In total knee arthroplasty, postoperative pain control is imperative in facilitating physical therapy and rehabilitation. Our study demonstrated a significant reduction in the incidence of severe pain with CFNB versus PCA, with lower pain scores to Day 3 post-TKA. In addition, we did not observe any adverse effects from CFNB, such as hypotension and respiratory depression. Thus, CFNB is a safe alternative for post-TKA pain control.



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Copyright © 2012, Iranian Society of Regional Anesthesia and Pain Medicine (ISRAPM). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License ( which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.
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2021-05-21 08:56:11
Thank you for this article.