Local Anaesthetic Infiltration as Opposed to Regional Nerve Block for Pain Management Post Total Knee Arthroplasty

Total knee arthroplasty (TKA) is a common surgical procedure for the management of end-stage knee osteoarthritis (Hsu and Siwiec 2023). Despite advances in surgical techniques, postoperative pain management remains a significant challenge for patients and healthcare professionals. Local anaesthetic infiltration (LAI) and regional nerve block (RNB) are two commonly used techniques for postoperative pain management after TKA. LAI involves the injection of a local anaesthetic agent into the tissues surrounding the surgical site, while RNB involves the injection of a local anaesthetic agent into the nerves that supply the knee joint (Hasegawa et al. 2022).

Enhanced Recovery After Surgery (ERAS) programmes are a multidisciplinary approach to postoperative care that aim to improve patient outcomes and reduce complications after surgery. One of the key components of ERAS programmes for total knee arthroplasty (TKA) is opioid-sparing analgesia. LAI and RNB are therefore recommended (Jiang et al. 2019). 

Some studies have found that combining RNB and LAI can provide superior pain relief compared to either technique alone. However, other studies have found no significant difference between using LAI alone or combining RNB with LAI. In summary, there is ongoing debate in the literature regarding the preference between RNB and LAI for postoperative pain management after TKA (Gudmundsdottir and Franklin 2017). 

In Malta, Mater Dei Hospital is the primary healthcare provider and a key centre for orthopaedic surgeries, including total knee arthroplasty (TKA). Locally, postoperative pain management in TKA patients has been a topic of interest for healthcare professionals, with the aim of improving patient outcomes and promoting faster recovery. At Mater Dei Hospital, the current approach to postoperative pain management involves the use of local anaesthetic infiltration (LAI) and regional nerve block (RNB), which are two widely used techniques in pain management following TKA. However, there is ongoing debate regarding the superiority of one technique over the other, as well as their respective side effect and complication profiles. This assignment will review the available literature on LAI and RNB in TKA patients, with a specific focus on their effectiveness, safety, complications, and impact on patient recovery. The findings will be contextualized within the local practice at Mater Dei Hospital, to provide recommendations and inform evidence-based guidelines for postoperative pain management in TKA patients.

As shown in table 1, the primary objective is to evaluate which technique provides superior pain relief while also considering the side effect and complication profile associated with each technique. 

The aim of this assignment is to compare the use of LAI with regional nerve block RNB for postoperative pain management in adults undergoing TKA. The assignment will focus on identifying the most effective and safest approach to postoperative pain management for patients undergoing TKA, with the goal of improving patient outcomes and promoting faster recovery after surgery. By conducting a comprehensive review of the literature, this assignment will also inform clinical practice and contribute to the development of evidence-based guidelines for postoperative pain management after TKA in the author’s local general hospital.

Table 1: PICO model constructing the research question

The search strategy involved a systematic search of electronic databases, including PubMed, Embase, and Cochrane Library, from January 2018 to September 2023, using relevant keywords and medical subject headings (MeSH) terms. The keywords, inclusion and exclusion criteria research are represented in table 2 below. 

The search strategy aimed to identify relevant studies to evaluate the effectiveness and safety of LAI and RNB for postoperative pain management in adults undergoing TKA, with a focus on reducing opioid use and associated complications and optimizing recovery outcomes according to ERAS protocols.

Table 2: Search strategy

The Critical Appraisal Skills Programme (2019) instrument was employed for the critical evaluation of the literature review, while the Harbour and Miller (2001) (Appendix 1) hierarchy of evidence served as the basis for grading the available evidence. The studies will be assessed following the sequence outlined in Table 3.

Table 3: Order of evaluation - To provide a comprehensive understanding of the use of LAI and RNB for postoperative pain management in TKA patients.

By assessing these studies in this specific order, the literature review aims to provide a thorough and systematic understanding of the benefits, limitations, and implications of using LAI and RNB for postoperative pain management in TKA patients.

Fenten et al. 2018, conducted a randomized control trial (RCT) comparing the effect of LAI and RNB – specifically femoral nerve block, after TKA. The study aimed to compare the effectiveness of femoral nerve catheter (FNC) and local infiltration for analgesia in fast-track total knee arthroplasty, focusing on short-term and long-term outcomes. The study is relevant to the PICO and search strategy discussed for this assignment.

The study was conducted at a single centre in the Netherlands from June 2013 to November 2015 and included 100 patients undergoing fast track total knee arthroplasty, randomized into two groups: femoral nerve catheter group (n = 50) and local infiltration group (n = 50). The primary outcome was the difference in visual analogue scale (VAS) pain score during walking on postoperative day 1. VAS is a valid tool to use for measuring subjective experiences such as pain intensity. It is widely used in clinical research and practice for assessing pain levels in patients. The VAS typically consists of a 10 cm line with anchors at each end, representing the extremes of pain experience (e.g., "no pain" and "worst pain imaginable"). Patients are asked to mark the point on the line that best represents their current pain level (Klimek et al. 2017). 

The secondary outcomes included pain at rest, opioid consumption, length of hospital stay, knee function, and patient satisfaction. The study employed a rigorous methodology, with strict inclusion and exclusion criteria and standardized protocols for anaesthesia and postoperative pain management, making it more rigorous. Fenten et al. 2018 registered this study in the Dutch Trial Registry (NTR3887) and obtained ethical approval.

In this study, patients were randomized into two groups: the femoral nerve catheter (FNC) group and the local infiltration analgesia (LIA) group. The FNC group received a continuous femoral nerve block with ropivacaine (0.2%, 5 mL/h), while the LIA group received periarticular infiltration with ropivacaine (0.2%, 150 mL) during surgery and an additional 60 mL at the end of surgery. Randomization was performed using a computer-generated list. There were no reported dropouts in the study. 

The study design, methods, and statistical analysis were appropriate for the research question, increasing the study’s level of reliability and validity.  As shown in table 3 and 4 below, the study found that there were no clinically significant differences in functional recovery between the femoral nerve block (FNB) and local infiltration analgesia (LIA) groups at 6 weeks, 3 months, and 1 year after operation. However, maximum pain scores at 3 months and 1 year after surgery were slightly but significantly higher in the LAI group, and the odds of taking analgesia for knee pain 1 year after surgery were almost six times higher in the LAI group. Patients in the FNB group had lower pain scores and less opioid consumption in the postoperative period. 

Table 4: NRS pain scores 3 and 12 months, displayed as mean (Sd) and differences between means adjusted for baseline pain score. CI, confidence interval; FNB, femoral nerval block; LIA, Local infiltration analgesia; NRS, numeric rating scale (Fenten et al. 2018).

Table 5: Functional performances displayed as means (SD) and adjusted differences for baseline performance. 6MWT, 6minute walk test; CI, confidence interval; FNB, femoral nerve block; LIA, Local infiltration analgesia; ROM, range of motion; SCT, stair climbing test (primary outcome test); TUG, timed up and go test (Fenten et al. 2018).

The study has a low risk of bias, as it employed rigorous methodology, including randomization, blinding, and intention-to-treat analysis. However, there are potential sources of bias, such as the small sample size and the use of only one centre, which limits the generalizability of the findings. Moreover, the study did not assess the cost-effectiveness of the two interventions, which is an important consideration for decision-making.

This study is a randomized controlled trial (RCT). According to the Harbour and Miller's hierarchy of evidence (Harbour and Miller 2001), this study would be placed at Level 2, as it is an RCT that provides a high level of evidence.

Overall, the study has high rigour, reliability, and validity, and a low risk of bias. However, the small sample size and the use of only one centre limit the generalizability of the findings. Future studies with larger sample sizes and multiple centres are needed to confirm the results and assess the cost-effectiveness of the interventions.

Talmo et al. 2018 conducted a prospective, randomized, double-blind study comparing periarticular injection (PAI) with liposomal bupivacaine to femoral nerve block in TKA with one year of follow-up after surgery. This study aimed to determine the impact of these different approaches and discuss their contribution on pain relief post TKA. 

A prospective, randomized, double-blind trial, is a strong study design that reduces bias and ensures a high level of internal validity in itself (David and Khandhar 2023). The randomization process ensures that the groups are comparable, and blinding helps to eliminate any potential influence from the researchers or participants. The study included 373 patients undergoing unilateral TKA, providing an adequately powered sample to detect statistically meaningful differences in outcome measures one year after surgery. 

The authors had well-defined inclusion and exclusion criteria, ensuring a homogeneous study population. This enhances the study's internal validity, but may limit the generalizability of the findings to other populations (Patino and Ferreira 2018). The authors used appropriate outcome measures, such as visual analogue scores (VAS) for pain, range of motion (ROM), ability to perform a straight leg raise (SLR), and walking distance, as well as Knee Society Score (KSS) and SF-12 score, to assess the effectiveness of the interventions. They also employed appropriate statistical tests and reported the relevant results and values, including p-values, which helps the reader assess the significance of the findings.

This trial involved two groups: the femoral nerve block (FNB) group and the intraoperative local anaesthetic injection of liposomal bupivacaine (ILALB) group. The FNB group received a preoperative single-injection femoral nerve block with 0.5% bupivacaine, while the ILALB group received an intraoperative injection of liposomal bupivacaine (266 mg/20 mL) diluted with 0.5% bupivacaine (20 mL) and normal saline (40 mL). Randomization was performed using a computer-generated random number table, and the allocation was concealed using sequentially numbered, opaque, sealed envelopes. The study did not report dropouts. 

The authors mentioned that, based on a power analysis, 100 participants per group were needed to identify meaningful differences in outcomes one year after surgery, and they recruited a total of 373 participants. However, the study lacks sufficient explanation about the confidence limits and power to validate this statement, which hampers the study's robustness and the inferences that can be made from the outcomes. Furthermore, the absence of information on some participants at the end of the study increases the potential for attrition bias, which could affect the study's overall reliability.

The findings of this study indicate that the FNB group experienced a notably superior analgesic outcome at 12 and 24-hours following surgery. However, beyond one day after the procedure, there was no discernible difference in pain scores between the two groups. Patients who received LAI were significantly more capable of performing SLR at 12 hours post-surgery, but this distinction was no longer evident after 12 hours. The relevance of these results to the author's situation is limited, as liposomal bupivacaine is considerably more costly than standard bupivacaine hydrochloride and various other local anaesthetic agents. Moreover, it is uncertain whether liposomal bupivacaine offers a substantially improved effect compared to standard bupivacaine.

This study was conducted with a high level of rigor, as evidenced by the study design, sample size, blinding, and selection criteria. This increases the confidence in the study's findings. The reliability of the study is supported by the use of standardized outcome measures and the consistency of the results across different time points. In terms of validity, the study has a high level of internal validity due to the rigorous design, randomization, and blinding. However, the external validity may be limited by the specific patient population and the exclusion criteria, which may not be representative of all patients undergoing TKA. Although the study minimized bias through randomization, blinding, and the use of appropriate statistical tests, the potential for bias remains, as the anaesthesiologist performing the nerve blocks was not blinded to the intervention. 

In the hierarchy of evidence, the study is a randomized controlled trial, which is considered a high level of evidence. According to Harbour and Miller Level of Evidence, this study can be graded at level 2 (Harbour and Miller 2001). This suggests that the study's findings are likely to be robust and reliable.

Overall, the study was well-conducted with a rigorous design, adequate sample size, and appropriate outcome measures. It demonstrated that while femoral nerve block provided superior pain relief in the first 24 hours after TKA compared to local anaesthetic injection with liposomal bupivacaine, there were no significant differences in pain relief or functional outcomes at 1 year postoperatively. The findings of this study should be considered in the context of its strengths and limitations, as well as the hierarchy of evidence.

The study by Kampitak et al. 2018 presents a well-designed, prospective, randomized, double-blind controlled trial that aimed to compare the effectiveness of single-injection adductor canal block (ACB) and single-injection local infiltration analgesia (LIA) in patients undergoing total knee arthroplasty (TKA). The primary outcome measured was total morphine consumption during 24 and 48 postoperative hours, with secondary outcomes including pain scores, mobility, quadriceps strength, patient satisfaction, side effects, and complications.

Participants were randomized into two groups: ACB and LIA. The primary outcome was total morphine consumption during the first 24 postoperative hours, and secondary outcomes included postoperative pain score, time to first and total dosage of rescue morphine in postoperative 48 hours, early and late postoperative period performance-based tests, and postoperative nausea and vomiting, among others. 

Randomization process was done using a computer-generated random number table, and sealed envelopes were used to conceal the allocation. The ACB group received an ultrasound-guided single-shot adductor canal block with 20 ml of 0.5% ropivacaine, while the LIA group received intraoperative infiltration of 100 ml of 0.2% ropivacaine solution mixed with 1 µg/kg epinephrine and 30 mg ketorolac. Infiltration was performed intraoperatively, not continuously. The study had no reported dropouts.

The mean Visual Analog Scale (VAS) scores at 6, 12, and 18 postoperative hours in the ACB group were significantly lower than the LIA group. Pain scores during various movements were also significantly lower in the ACB group compared to the LIA group on postoperative days 1 and 2. No significant differences were found between the ACB and LIA groups regarding patient satisfaction, incidence of nausea, vomiting, pruritus, or any documented complications directly attributable to the nerve blocks (Kampitak et al. 2018).

One of the strengths of the study is its rigorous design, which contributes to the validity of the results. Additionally, the researchers employed a multimodal analgesic regimen in both groups, minimizing confounding factors and ensuring a fair comparison. Furthermore, the comprehensive assessment of outcomes provides a holistic view of the impact of ACB and LIA on patient recovery. Moreover, double-blinding ensured minimized bias and improved the validity of the results. A clear hypothesis and well-defined primary and secondary outcomes were included. The sample size was calculated considering α and β values, and the study enrolled enough participants to account for potential dropouts. Appropriate statistical tests were used for data analysis, including repeated-measures ANOVA, Chi-square test, Fisher's exact test, and independent t-test. Analysis of variance (ANOVA) is appropriate for analyzing data in randomized controlled trials (RCTs) when the objective is to compare the means of multiple groups or conditions (Vickers 2005). 

However, there are some limitations to the study. A larger sample size could have further reduced bias and strengthened the study's conclusions. The use of only one experienced anaesthesiologist might limit the generalizability of the results, as it does not account for potential variability in the effectiveness of the ACB due to different practitioners. Moreover, the difference in injection site for the ACB group might have affected the spread of local anaesthetic drugs and influenced the duration and effectiveness of pain relief and physical outcomes.

These strengths and weaknesses impact the overall rigor, reliability, and generalizability of the study. The strengths indicate that single-injection ACB might provide superior pain relief and facilitate earlier mobility after TKA than single-injection LIA. However, the weaknesses raise concerns about the generalizability of the findings and the potential impact of variations in the injection site on pain relief and physical outcomes.

Using the Harbour and Miller Criteria, this study can be categorized as a Level 1b study, given its design as a well-conducted, randomized controlled trial (Harbour and Miller 2001). 

Overall, the study by Kampitak et al. 2018 appears to be rigorous and reliable, with a well-designed methodology, appropriate statistical tests, and a clear hypothesis. The double-blinded design ensures the validity of the results and minimizes the risk of bias. However, the single-centre nature of the study may limit its generalizability, and the primary outcome's time frame may not provide a comprehensive understanding of the long-term effects. It provides evidence that single-injection ACB may be more effective in reducing postoperative morphine consumption and pain scores and facilitating earlier mobility than single-injection LIA in patients undergoing TKA. Nevertheless, the limitations of the study, including potential generalizability issues and variations in the injection site, should be considered when interpreting the results. Future research with larger sample sizes and more diverse settings could help to further establish the superiority of one technique over the other.

In a single-centre, randomized controlled trial, Kastelik et al. 2019 compared local infiltration analgesia (LIA) and nerve block procedures for patients undergoing primary total knee arthroplasty (TKA) to assess the impact of the LIA technique on postoperative outcomes. The authors aimed to investigate whether the LIA approach in general anaesthesia could provide better results in terms of early mobilization, pain management, and patient satisfaction.

The study was conducted with 40 patients allocated to either the LIA or nerve block (NB) group. The primary outcome was time to first walking on the ward. Secondary outcomes included pain scores, patient satisfaction, and procedural time. The randomization process was done using a computer-generated random number table, and allocation concealment was achieved using opaque envelopes. The LIA group received periarticular infiltration of a mixture containing 200 mg ropivacaine, 30 mg ketorolac, and 0.5 mg epinephrine diluted in 0.9% saline to a total volume of 100 ml. Infiltration was performed intraoperatively, not continuously. The NB group received a combination of sciatic nerve and adductor canal blocks. Secondary outcomes included joint mobility, postoperative functional parameters, analgesic use, and pain scores. There were no dropouts in the study, and all nerve blocks were performed successfully.

There was no significant difference in early mobilization after TKA between the LIA and nerve block groups. The time to first walking on the ward was 24.0 ± 7.2 hours in LIA patients compared to 27.1 ± 12.4 hours in nerve block patients. LIA patients reported higher pain scores on mild exertion, especially on later postoperative days. However, resting pain scores were similar between groups, and the postoperative oral morphine requirements during the first five days after surgery showed no significant difference. Patients in the LIA group had a significant reduction in anaesthesia induction time compared to the nerve block group (10.0 vs 35.0 minutes). The actual operating time was comparable between the two groups. Despite elevated pain scores on the fifth postoperative day, LIA patients reported excellent satisfaction with the procedure.


The study used a randomized controlled trial design, which is considered the gold standard for evaluating the efficacy of interventions (Hariton and Locascio 2018).  By providing clear primary and secondary endpoints, the authors demonstrated a rigorous approach to evaluating the effectiveness of the interventions. The authors measured multiple outcomes to provide a comprehensive assessment of the LIA technique's impact on postoperative outcomes. There was a 0% dropout rate, and all nerve blocks were performed successfully, indicating good adherence to the study protocol.

The study was however not blinded, potentially introducing bias, and affecting the reliability of the results. The single-centre design with limited surgeons and anaesthesiologists involved may limit the generalizability of the findings. The study had a small sample size, which could limit the statistical power to detect significant differences between the two groups. Additionally, the study did not include a long-term follow-up to evaluate the sustainability of the observed effects.

The study's rigor was limited by its lack of blinding, single-centre design, and small sample size. These limitations may have affected the reliability and validity of the findings. Bias may have been introduced due to the lack of blinding, potentially leading to over- or underestimation of the true effects of the interventions.

Using the Harbour and Miller Criteria, this study would be considered level 2 evidence due to the lack of blinding, single-centre design, and small sample size (Harbour and Miller 2001).

Overall, Kastelik et al.'s study provides preliminary evidence supporting the use of the LIA approach in general anaesthesia for early recovery after TKA surgery. However, the study's limitations, including the lack of blinding, single-centre design, and small sample size, may affect the reliability and validity of the findings. Further research with larger sample sizes, multicentre designs, and long-term follow-up is necessary to validate these findings and establish the hierarchy of evidence for the LIA technique in TKA.

Comparing the above studies, it is evident that there is a need to address the approach taken at Mater Dei Hospital, the author's hospital, in Malta, in order to optimize pain management strategies in patients undergoing TKA. To achieve this, the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) system was used (Grading of Recommendations and Levels of Evidence. 2010). 

Table 5: Recommendations to consider in order to achieve optimal pain management in patients undergoing TKA

In conclusion, this assignment aimed to evaluate the efficacy of local anaesthetic infiltration (LAI) versus regional nerve blocks (RNBs) in reducing pain and assessing the side effect/complication profile in adults undergoing total knee arthroplasty (TKA). A comprehensive search of the literature identified four relevant studies, which were appraised using the Critical Appraisal Skills Programme (CASP) framework. 

The key findings from these studies demonstrated that both LAI and RNB provided effective postoperative pain management, with comparable outcomes in terms of pain reduction and functional recovery post total knee arthroplasty. However, differences in side effect profiles and complications were observed across the studies, indicating the importance of considering individual patient factors when selecting a pain management strategy.

The overall validity of the findings is supported by the robust methodology of the included studies, such as randomized controlled trial designs and appropriate statistical analyses. These results have important implications for current practice, both at the author's local hospital in Malta and in general terms. The development and implementation of a standardized pain management protocol, incorporating the best available evidence, are recommended to optimize patient outcomes and ensure that care is aligned with the latest research and best practices.

In summary, this assignment has provided a critical appraisal of the literature comparing LAI and RNB for pain management in TKA, demonstrating that both techniques can be effective in managing postoperative pain. The findings highlight the need for individualized, evidence-based approaches to pain management in TKA, and offer valuable insights for improving patient care in the author's local hospital and beyond.