Local Infiltration Analgesia for Postoperative Pain After Hip Arthroplasty: A Systematic Review and Meta-Analysis

A Network Meta-Analysis of Randomized Controlled Trials Assessing Intraoperative Anesthetic Therapies for Analgesic Efficacy and Morphine Consumption Following Total Knee Arthroplasty

BACKGROUND

The purpose of this study was to compare intraoperative anesthetic therapies for total knee arthroplasty (TKA) regarding postoperative analgesic efficacy and morphine consumption by conducting a systematic literature search.

METHODS

Randomized controlled trials of TKA using various anesthetic therapies were identified from various databases from conception through December 31, 2021. A network meta-analysis of relevant literature was performed to investigate which treatment showed better outcomes. In total, 40 trials were included in this study.

RESULTS

Surface under the cumulative ranking curve showed local infiltration anesthesia (LIA) with saphenous nerve block (SNB) to produce the best pain relief on postoperative days (PODs) 1 and 2 and the best reduction of morphine consumption on PODs 1 and 3. However, femoral nerve block showed the largest effect on pain relief on POD 3, and liposomal bupivacaine showed the largest effect on reduction of morphine consumption on POD 2.

CONCLUSIONS

According to this network meta-analysis, surface under the cumulative ranking curve percentage showed that LIA with SNB provided the best analgesic effect after TKA. Furthermore, patients receiving LIA with SNB had the lowest consumption of morphine. Although femoral nerve block resulted in better pain relief on POD 3, LIA with SNB could be selected first when trying to reduce morphine consumption or increase early ambulation.

Efficacy of Supplemental Ultrasound-Guided Pericapsular Nerve Group (PENG) Block Combined with Lateral Femoral Cutaneous Nerve Block in Patients Receiving Local Infiltration Analgesia after Hip Fracture Surgery: A Prospective Randomized Controlled Trial

Background and Objectives: Local infiltration analgesia (LIA) represents a potential approach to reducing pain in patients undergoing total hip arthroplasty (THA). The pericapsular nerve group (PENG) block also provides adequate analgesia for fractures and THA. As most hip surgeries use a lateral incision, affecting the cutaneous supply by branches of the lateral femoral cutaneous nerve (LFCN), the LFCN block can contribute to postoperative analgesia. However, no studies have investigated the effectiveness of supplemental PENG block combined with LFCN block in patients undergoing LIA after hip fracture surgery. Our study aimed to assess the effectiveness of PENG combined with LFCN block following hip fracture surgery in patients who underwent LIA. Materials and Methods: Forty-six patients were randomly assigned to LIA or PENG + LFCN + LIA groups. The primary outcome was the pain score at rest and during movement at 2, 6, 12, 24, and 48 h postoperatively. The total opioid dose for postoperative analgesia was also measured at the same time points. Secondary outcomes included postoperative cognitive function assessment. Results: The median pain scores at rest and during movement were lower in the PENG + LFCN + LIA group throughout the study periods compared to the LIA group, except at 2 h (at rest) and 48 h (during movement) after surgery. The total fentanyl dose was lower in the PENG + LFCN + LIA group at all time points after surgery when compared to the LIA group. Postoperative delirium incidence and the median abbreviated mental test scores were not significantly different between the two groups. Conclusions: The combination of PENG and LFCN blocks may contribute to enhanced recovery for patients undergoing LIA after hip fracture surgery. However, further well-controlled research is necessary to determine the effectiveness of supplemental PENG combined with LFCN block in addressing cognitive deficits in these patients.

Analgesic efficacy of local infiltration anaesthesia versus femoral nerve block in alleviating postoperative wound pain following total knee arthroplasty: A systematic review and meta-analysis

Total knee arthroplasty (TKA) often involves significant postoperative pain, necessitating effective analgesia. This meta-analysis compares the analgesic efficacy of local infiltration anaesthesia (LIA) and femoral nerve block (FNB) in managing postoperative wound pain following TKA. Adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, this meta-analysis was structured around the PICO framework, assessing studies that directly compared LIA and FNB in TKA patients. A comprehensive search across PubMed, Embase, Web of Science and the Cochrane Library was conducted without time restrictions. Studies were included based on specific criteria such as participant demographics, study design and outcomes like pain scores and opioid consumption. Quality assessment utilized the Cochrane Collaboration's risk of bias tool. The statistical approach was determined based on heterogeneity, with the choice of fixed- or random-effects models guided by the I2 statistic. Sensitivity analysis and evaluation of publication bias using funnel plots and Egger's linear regression test were also conducted. From an initial pool of 1275 articles, eight studies met the inclusion criteria. These studies conducted in various countries from 2007 to 2016. The meta-analysis showed no significant difference in resting and movement-related Visual Analogue Scale scores post-TKA between the LIA and FNB groups. However, LIA was associated with significantly lower opioid consumption. The quality assessment revealed a low risk of bias in most studies, and the sensitivity analysis confirmed the stability of these findings. There was no significant publication bias detected. Both LIA and FNB are effective in controlling postoperative pain in TKA patients, but LIA offers the advantage of lower opioid consumption. Its simplicity, cost-effectiveness and opioid-sparing nature make LIA the recommended choice for postoperative analgesia in knee replacement surgeries.

Local infiltration analgesia does not have benefits in fast-track hip arthroplasty programmes: a double-blind, randomised, placebo-controlled, clinical trial

BACKGROUND

Multimodal analgesia regimes including local infiltration analgesia (LIA) have been successfully applied in fast-track hip arthroplasty programmes. LIA's contribution to the analgesic effect in hip arthroplasty has been questioned. Our study sought to determine the analgesic efficacy of LIA in THA surgery in a fast-track programme.

METHODS

Patients diagnosed with hip osteoarthritis scheduled for arthroplasty were randomised to receive LIA (120 ml ropivacaine 0.2% plus epinephrine 0.5 µ/ml) or saline as a part of a multimodal analgesia regime. The surgical team, the nursing staff, and patients were all blinded regarding patient allocation throughout the study. The primary outcome was pain assessed as a continuous variable using the visual analogue scale (VAS) at 4, 8, 24 and 48 hours postoperatively. Secondary outcomes included the amount of analgesic rescue consumption, complications and length of hospital stay.

RESULTS

A total of 63 patients were interviewed and agreed to participate in the study. No statistically significant differences were found between groups for pain measurements at 4, 8, 12, 24 and 48 hours after surgery. There were also no differences in rescue medication consumption, complications, or length of stay.

CONCLUSIONS

Our results suggest LIA (ropivacaine plus epinephrine, single shot) has no effect in pain management and has not shown benefits for early ambulation in primary THA surgery. Further research is needed to establish the optimal multimodal analgesia regime for THA fast-track programmes.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov (NCT03513276).

Analgesic Effects of Ultrasound-Guided Iliohypogastric/Ilioinguinal Nerve Block Combined with Lateral Femoral Cutaneous Nerve Block in Total Hip Arthroplasty via Direct Anterior Approach: A Retrospective Cohort Study

Objective

This study aimed to explore the efficacy and safety of the combination of lateral femoral cutaneous nerve blocks (LFCNB) and iliohypogastric/ilioinguinal nerve blocks (IHINB) on postoperative pain and functional outcomes after total hip arthroplasty (THA) via the direct anterior approach (DAA).

Methods

In this retrospective cohort study, patients undergoing THA via the DAA between January 2019 and November 2019 were stratified into two groups based on their date of admission. Sixty‐seven patients received LFCNB and IHINB along with periarticular infiltration analgesia (PIA) (nerve block group), and 75 patients received PIA alone (control group). The outcomes included postoperative morphine consumption, postoperative pain assessed using the visual analogue scale (VAS), the QoR‐15 score, and functional recovery measured as quadriceps strength, time to first straight leg rise, daily ambulation distance, and duration of hospitalization. The Oxford hip score and the UCLA activity level rating were assessed at 1 and 3 months after surgery. In addition, postoperative complications were recorded. Patients were also compared based on the type of incision used during surgery (traditional longitudinal or “bikini” incision).

Results

Patients in the nerve block group showed significantly lower postoperative morphine consumption, lower resting VAS scores within 12 h postoperatively, lower VAS scores during motion within 24 h postoperatively, and better QoR‐15 scores on postoperative day 1. These patients also showed significantly better functional recovery during hospitalization. At 1‐month and 3‐month outpatient follow up, the two groups showed no significant differences in Oxford hip score or UCLA activity level rating. There were no significant differences in the incidence of postoperative complications. Similar results were observed when patients were stratified by type of incision, except that the duration of hospitalization was similar.

Conclusion

Compared to PIA alone, a combination of LFCNB and IHINB along with PIA can improve early pain relief, reduce morphine consumption, and accelerate functional recovery, without increasing complications after THA via the DAA.

Efficacy of Periarticular Multimodal Drug Injection Without NSAIDs in Elderly Patients With Displaced Femoral Neck Fractures Undergoing Bipolar Hemiarthroplasty: A Prospective Triple-Blinded RCT

Introduction Recently, periarticular multimodal drug injection (PMDI) has demonstrated the ability to significantly reduce early postoperative pain with hip fractures in the elderly. Nonetheless, data on PMDI without non-steroidal anti-inflammatory drugs (NSAIDs) in these patients are still doubtful. The current study has evaluated the effect of PMDI with NSAIDs in elderly femoral neck fractures (FNFs) underlying bipolar hip arthroplasty (BHA). Materials and methods A prospective triple-blinded randomized controlled trial (RCT) was conducted in 28 elderly FNFs undergoing BHA. They were randomized into two groups: PMDI group (n=14), which received intraoperative PMDI (50-mL solution of 100-mg bupivacaine, 10-mg morphine, 300-mcg epinephrine, and 750-mg cefuroxime), and a placebo group (n=14), which received only saline solution. The primary outcome was a 10-point visual analog scale (VAS). Secondary outcomes were morphine consumption and cumulative ambulatory score (CAS), postoperative complications, and functional outcomes as a timed up-and-go (TUG) test and Harris hip score (HHS) at two, six, and 12 weeks postoperatively. Results The PMDI group demonstrated a significant reduction in the median VAS at the 48th hour postoperatively as compared to the placebo group (P = 0.019), and a non-significant reduction in the median VAS at the 36th and 60th hours (P = 0.058 and 0.110, respectively) and in a median dosage of morphine consumption on the second postoperative day (P = 0.140). There was no significant difference in postoperative ambulation and functional outcome between both groups (P > 0.05, all). Conclusion The PMDI regimen without NSAIDs is effective for postoperative analgesia on the second postoperative day in elderly FNFs undergoing BHA without any significant difference in functional outcome or postoperative complications.

Intrathecal versus local infiltration analgesia for pain control in total joint arthroplasty

BACKGROUND

The purpose of this meta-analysis was to assess the efficacy of intrathecal morphine (ITM) analgesia and local infiltration analgesia (LIA) for pain control in total joint arthroplasty (TJA).

METHODS

Embase, PubMed, the Cochrane Library, and Web of Science were systematically searched for randomized controlled trials (RCTs). All RCTs were comparing intrathecal analgesia and local infiltration analgesia in TJA. Primary outcomes were the visual analog scale (VAS) score with rest or mobilization up to 72 h. Secondary outcomes were the total morphine consumption, length of hospital stay, and morphine-related complications.

RESULTS

Compared with the intrathecal analgesia group, the LIA group was associated with a reduction in VAS score with rest up to 72 h. Moreover, LIA was associated with a decrease in VAS score with mobilization at 6 h, 12 h, 48 h, and 72 h. Moreover, LIA significantly reduced total morphine consumption (weighted mean difference (WMD)  = - 15.37, 95% CI - 22.64 to - 8.83, P  = 0.000), length of hospital stay (WMD  =  - 1.39, 95% CI - 1.67 to - 1.11, P  = 0.000), and morphine-related complications (nausea and pruritus).

CONCLUSIONS

Local infiltration provided superior analgesia and morphine-sparing effects within the first 72 h compared with ITM following TJA.

Impact of Local Infiltration Analgesia on the Quality of Recovery After Anterior Total Hip Arthroplasty: A Randomized, Triple-Blind, Placebo-Controlled Trial

BACKGROUND

Local infiltration analgesia (LIA) is commonly used in anterior total hip arthroplasty (THA) surgery; however, evidence for its efficacy is lacking. We hypothesized that LIA with 0.2% ropivacaine when compared with injection of placebo (0.9% saline) would improve patient quality of recovery on postoperative day (POD) 1, as measured by the Quality of Recovery-15 (QoR-15) score.

METHODS

Patients scheduled to have a primary unilateral anterior THA with a single surgeon in a tertiary level metropolitan hospital were randomized to receive LIA with either 2.5 mL/kg of 0.2% ropivacaine or 0.9% saline as placebo. Patients and clinical and study personnel were blinded to group allocation. Perioperative care was standardized and this included spinal anesthesia and oral multimodal analgesia. The primary outcome was a multidimensional (pain, physical comfort, physical independence, emotions, and psychological support) patient-reported quality of recovery scale, QoR-15, measured on POD 1.

RESULTS

One hundred sixty patients were randomized; 6 patients were withdrawn after randomization and 2 patients had incomplete outcome data. The intention-to-treat analysis included 152 patients. The median (interquartile range [IQR]) QoR-15 score on POD 1 of the ropivacaine group was 119.5 (102-124), compared with the placebo group which had a median (IQR) of 115 (98-126). The median difference of 2 (95% confidence interval [CI], -4 to 7; P = .56) was not statistically or clinically significant. An as-per-protocol sensitivity analysis of 146 patients who received spinal anesthesia without general anesthesia, and the allocated intervention, also showed no evidence of a significant difference between groups. Secondary outcomes (worst pain numerical rating scale at rest and with movement on POD 1, opioid consumption on PODs 1 and 2, mobilization on POD 1, Brief Pain Inventory severity and interference on POD 90, and length of stay) were similar in both groups.

CONCLUSIONS

LIA with 0.2% ropivacaine when compared with 0.9% saline as placebo did not improve quality of recovery 1 day after anterior THA.

[Infiltration anesthesia]

OBJECTIVE

Complete anesthesia of any skin and soft tissue area by intradermal, subcutaneous, or intramuscular injections.

INDICATIONS

Small injuries or incisions in limbs or trunk, minor surgery on the face/jaw (e.g., on the teeth), or postoperative analgesia (local infiltration anesthesia, LIA).

CONTRAINDICATIONS

Local infections at the injection site.

SURGICAL TECHNIQUE

By means of intradermal, subcutaneous or intramuscular administration, a grandeur arises, here the local anesthetic blocks nerve transmission. If anesthetized distal to end arteries, vasoconstrictors (e.g., epinephrine) should be avoided. Proximal to end arteries, localized ischemia may facilitate operative care.

POSTOPERATIVE MANAGEMENT

The effect of local anesthesia is self-limiting.

RESULTS

By means of infiltration anesthesia or "field block", larger areas of skin are easily accessible for surgical treatment. The amount to be applied has to be adapted to the extent of the operation and the maximal dose. Postoperatively, after knee or hip arthroplasty, analgesia consumption can be reduced, and early mobilization promoted using LIA.

Regional and Multimodal Analgesia to Reduce Opioid Use After Total Joint Arthroplasty: A Narrative Review

BACKGROUND

Elective total joint arthroplasty may be a gateway to long-term opioid use.

QUESTIONS/PURPOSE

We sought to review the literature on multimodal and regional analgesia as a strategy to minimize perioperative opioid use and control pain in patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA).

METHODS

We conducted a narrative review to assess the state of the evidence informing opioid-sparing analgesics for THA and TKA. A PubMed search was conducted for English-language articles published before April 2018. We preferentially included well-designed randomized controlled trials, systematic reviews, and meta-analyses. Where the highest levels of evidence were not yet apparent, we evaluated retrospective and/or observational studies.

RESULTS

Multimodal analgesia emphasizing nonsteroidal anti-inflammatory agents and acetaminophen is associated with decreases in perioperative opioid use for THA and TKA. Regional analgesia, including peripheral nerve blocks and local infiltration analgesia, is also associated with decreased perioperative opioid use for THA and TKA. Emerging topics in post-arthroplasty analgesia include (1) the value of nonsteroidal anti-inflammatory drugs, (2) the use of peripheral nerve catheters and extended-release local anesthetics to prolong the duration of opioid-free analgesia, and (3) novel peripheral nerve blocks, exemplified by the IPACK (interspace between the popliteal artery and posterior capsule of the knee) block for TKA.

CONCLUSIONS

The use of multimodal analgesia with regional techniques may decrease perioperative opioid use for patients undergoing THA and TKA. These techniques should be part of a comprehensive perioperative plan to promote adequate analgesia while minimizing overall opioid exposure.

The role of elastomeric pumps in postoperative analgesia in orthopaedics and factors affecting their flow rate

Elastomeric pumps are mechanical devices composed of an elastomeric balloon reservoir into which the drug to be infused is stored, a protective casing (used by some manufacturers), a flow controller and a wound catheter. In orthopaedics they are used to provide continuous local infiltration analgesia. In this way patients rely less on other routes of analgesia and thus avoid their systemic side effects. Studies have shown good response to analgesia with these pumps for the first 24 hours but their benefit is not as clear at 48 and 72 hours. There are numerous factors that affect the flow rate of elastomeric pumps. Some are inherent to all elastomeric pumps such as: the pressure exerted by the elastomeric balloon, catheter size, the vertical height of the pump in relation to the wound, viscosity and partial filling. There are also other factors which vary according to the manufacturer such as: the optimal temperature to obtain the desired flow rate as this directly affects viscosity, the dialysate that the analgesic drug is mixed with (ie normal saline or 5% dextrose), and the storage conditions of the fluid to be infused. It is thus essential to follow the clinical guidelines provided by the manufacturer in order to obtain the desired flow rate.

Continuous Posterior Lumbar Plexus Nerve Block Versus Periarticular Injection with Ropivacaine or Liposomal Bupivacaine for Total Hip Arthroplasty: A Three-Arm Randomized Clinical Trial

BACKGROUND

Debate surrounds the issue of whether peripheral nerve blockade or periarticular infiltration (PAI) should be employed within a contemporary, comprehensive multimodal analgesia pathway for total hip arthroplasty. We hypothesized that patients treated with a continuous posterior lumbar plexus block (PNB) would report less pain and consume less opioid medication than those treated with PAI.

METHODS

This investigator-initiated, independently funded, 3-arm randomized clinical trial (RCT) performed at a single high-volume institution compared postoperative analgesia interventions for elective, unilateral primary total hip arthroplasty: (1) PNB; (2) PAI with ropivacaine, ketorolac, and epinephrine (PAI-R); and (3) PAI with liposomal bupivacaine, ketorolac, and epinephrine (PAI-L) using computerized randomization. The primary outcome was maximum pain during the morning (06:00 to 12:00) of the first postoperative day (POD) on an ascending numeric rating scale (NRS) from 0 to 10. Pairwise treatment comparisons were performed using the rank-sum test, with a p value of <0.017 indicating significance (Bonferroni adjusted). A sample size of 150 provided 80% power to detect a difference of 2.0 NRS units.

RESULTS

We included 159 patients (51, 54, and 54 patients in the PNB, PAI-R, and PAI-L groups, respectively). No significant differences were found with respect to the primary end point on the morning of the first POD (median, 3.0, 4.0, and 3.0, respectively; p > 0.033 for all). Opioid consumption was low and did not differ across groups at any intervals. Median maximum pain on POD 1 was 5.0, 5.5, and 4.0, respectively, and was lower for the PAI-L group than for the PAI-R group (p = 0.006). On POD 2, maximum pain (median, 3.5, 5.0, and 3.5, respectively) was lower for the PNB group (p = 0.014) and PAI-L group (p = 0.016) compared with the PAI-R group. The PAI-L group was not significantly different from the PNB group with respect to any outcomes: postoperative opioid use including rescue intravenous opioid medication, length of stay, and hospital adverse events, and 3-month follow-up data including any complication.

CONCLUSIONS

In this RCT, we found a modest improvement with respect to analgesia in patients receiving PNB compared with those receiving PAI-R, but not compared with those who had PAI-L. Secondary analyses suggested that PNB or PAI-L provides superior postoperative analgesia compared with PAI-R. For primary total hip arthroplasty, a multimodal analgesic regimen including PNB or PAI-L provides opioid-limiting analgesia.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Lateral femoral cutaneous nerve block after total hip arthroplasty: a randomised trial

BACKGROUND

Peripheral regional nerve blocks are commonly used for pain management after lower extremity surgery, but motor blockade can be a significant concern. The lateral femoral cutaneous nerve (LFCN) is a purely sensory nerve from the lumbar plexus. We hypothesised that an LFCN block would reduce movement-related pain after total hip arthroplasty (THA) in patients with moderate-to-severe pain.

METHODS

Sixty patients with visual analogue scale (VAS) score > 40 mm during 30-degree active flexion of the hip on either the first or second postoperative day after THA were included in this prospective, randomised, blinded, placebo-controlled trial. Group A received an LFCN block with 8 ml of 0.75% ropivacaine followed after 45 min by an additional LFCN block with 8 ml of saline. Group B received an LFCN block with 8 ml of saline followed after 45 min by an additional LFCN block with 8 ml of 0.75% ropivacaine.

RESULTS

We found a difference of 17 mm (95% CI, 4-31 mm; P < 0.02) in VAS pain score during 30-degree flexion of the hip 45 min after the first block (primary outcome) in favour of group A. No other significant difference between groups regarding pain during mobilisation and at rest was found. The overall non-responder rate (< 15 mm pain reduction) was 42%.

CONCLUSIONS

LFCN block reduced movement-related pain in patients with moderate-to-severe pain after THA. The substantial non-responder rate limits recommendations of this block as part of a standard analgesic treatment regimen.

Effect of lateral femoral cutaneous nerve-block on pain after total hip arthroplasty: a randomised, blinded, placebo-controlled trial

BACKGROUND

Total hip arthroplasty (THA) is a common procedure associated with moderate postoperative pain. No nerve block without loss of motor function has been documented for THA. We hypothesised that an ultrasound-guided lateral femoral cutaneous nerve (LFCN) block added to a multimodal postoperative pain regimen would reduce postoperative pain after THA.

METHODS

One hundred patients who had a THA by the posterior approach were evaluated in this randomised, placebo-controlled, blinded, parallel-group trial comparing an ultrasound-guided LFCN-block with either 8 ml of ropivacaine, 7.5 mg/ml, (Group Ropivacaine) or 8 ml of saline (Group Placebo) given postoperatively. Surgery was performed under spinal anaesthesia. The primary outcome was pain (measured on a Visual Analogue Scale (VAS)) 4 h post-blockade during 30° flexion of the hip. Secondary outcomes were pain at rest, pain during movement, oxycodone consumption (0-24 h), time to mobilisation, ability to mobilise, and length of stay. Patients, assessors and all staff involved with patient care were blinded to the intervention.

RESULTS

There was no difference in primary outcome between Group Ropivacaine and Group Placebo (VAS 27 mm vs. 31 mm, p = 0.41; difference -5 mm (95% CI: -15 mm - +5 mm). No differences in any of the secondary outcomes were observed. No adverse events, or harms, were observed during the trial.

CONCLUSION

Pain scores, opioid use, time to mobilisation, and length of stay were low in both Group Ropivacaine and Group Placebo. We found no added analgesic effect of a LFCN-block when combined with paracetamol and ibuprofen after THA by the posterior approach.

TRIAL REGISTRATION

EudraCT: 2013-004501-12 (December 16th 2013).

Is Local Infiltration Analgesia Superior to Peripheral Nerve Blockade for Pain Management After THA: A Network Meta-analysis

BACKGROUND

Local infiltration analgesia and peripheral nerve blocks are common methods for pain management in patients after THA but direct head-to-head, randomized controlled trials (RCTs) have not been performed. A network meta-analysis allows indirect comparison of individual treatments relative to a common comparator; in this case placebo (or no intervention), epidural analgesia, and intrathecal morphine, yielding an estimate of comparative efficacy.

QUESTIONS/PURPOSES

We asked, when compared with a placebo, (1) does use of local infiltration analgesia reduce patient pain scores and opioid consumption, (2) does use of peripheral nerve blocks reduce patient pain scores and opioid consumption, and (3) is local infiltration analgesia favored over peripheral nerve blocks for postoperative pain management after THA?

METHODS

We searched six databases, from inception through June 30, 2014, to identify RCTs comparing local infiltration analgesia or peripheral nerve block use in patients after THA. A total of 35 RCTs at low risk of bias based on the recommended Cochrane Collaboration risk assessment tool were included in the network meta-analysis (2296 patients). Primary outcomes for this review were patient pain scores at rest and cumulative opioid consumption, both assessed at 24 hours after THA. Because of substantial heterogeneity (variation of outcomes between studies) across included trials, a random effect model for meta-analysis was used to estimate the weighted mean difference (WMD) and 95% CI. The gray literature was searched with the same inclusion criteria as published trials. Only one unpublished trial (published abstract) fulfilled our criteria and was included in this review. All other studies included in this systematic review were full published articles. Bayesian network meta-analysis included all RCTs that compared local infiltration analgesia or peripheral nerve blocks with placebo (or no intervention), epidural analgesia, and intrathecal morphine.

RESULTS

Compared with placebo, local infiltration analgesia reduced patient pain scores (WMD, -0.61; 95% CI, -0.97 to -0.24; p = 0.001) and opioid consumption (WMD, -7.16 mg; 95% CI, -11.98 to -2.35; p = 0.004). Peripheral nerve blocks did not result in lower pain scores or reduced opioid consumption compared with placebo (WMD, -0.43; 95% CI, -0.99 to 0.12; p = 0.12 and WMD, -3.14 mg, 95% CI, -11.30 to 5.02; p = 0.45). However, network meta-analysis comparing local infiltration analgesia with peripheral nerve blocks through common comparators showed no differences between postoperative pain scores (WMD, -0.36; 95% CI, -1.06 to 0.31) and opioid consumption (WMD, -4.59 mg; 95% CI, -9.35 to 0.17), although rank-order analysis found local infiltration analgesia to be ranked first in more simulations than peripheral nerve blocks, suggesting that it may be more effective.

CONCLUSIONS

Using the novel statistical network meta-analysis approach, we found no differences between local infiltration analgesia and peripheral nerve blocks in terms of analgesia or opioid consumption 24 hours after THA; there was a suggestion of a slight advantage to peripheral nerve blocks based on rank-order analysis, but the effect size in question is likely not large. Given the slight difference between interventions, clinicians may choose to focus on other factors such as cost and intervention-related complications when debating which analgesic treatment to use after THA.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Analgesic Effects of Danggui-Shaoyao-San on Various "Phenotypes" of Nociception and Inflammation in a Formalin Pain Model

Danggui-Shaoyao-San (DSS) is a traditional Chinese medicine, which has long been used for pain treatment and has been demonstrated to possess anti-oxidative, cognitive enhancement, and anti-depressant effects. In the present study, the effects of aqueous extracts of DSS on spontaneous pain behaviors and long-term hyperalgesia were examined to investigate the anti-nociceptive effects and underlying mechanisms. Single pretreatment of DSS dose-dependently reduced spontaneous flinches/licking time in the second, rather than the first, phase after subcutaneous injection of 5 % formalin into one hindpaw, in doses of 2.4 and 9.6 g/kg. DSS also dose-dependently inhibited FOS and cyclooxygenase-2 (COX-2) expression in both superficial and deep layers within the spinal dorsal horn. Further, DSS reduced hypoalgesia in the injected paw from 1 to 3 days and produced anti-hyperalgesic actions in both the injected paw after 3 days and non-injected paw. These data suggest involvement of enhancement of descending pain inhibition by suppression of 5-HTT levels in the spinal dorsal horn and reduction of peripheral long-term inflammation, including paw edema and ulcers. These findings suggest that DSS may be a useful therapeutic agent for short- and long-term inflammation induced pain, through both anti-inflammatory and suppression of central sensitization mechanisms.