Local Infiltration Analgesia With Liposomal Bupivacaine Improves Pain Scores and Reduces Opioid Use After Total Knee Arthroplasty: Results of a Randomized Controlled Trial

Driving Forces for Outpatient Total Hip and Knee Arthroplasty with Enhanced Recovery After Surgery Protocols: A Narrative Review

PURPOSE OF REVIEW

To explore the recent developments and trends in the anesthetic and surgical practices for total hip and total knee arthroplasty and discuss the implications for further outpatient total joint arthroplasty procedures.

RECENT FINDINGS

Between 2012 and 2017 there was an 18.9% increase in the annual primary total joint arthroplasty volume. Payments to physicians falling by 7.5% (14.9% when adjusted for inflations), whereas hospital reimbursements and charges increased by 0.3% and 18.6%, respectively. Total knee arthroplasty and total hip arthroplasty surgeries were removed from the Medicare Inpatient Only in January 2018 and January 2020, respectively leading to same-day TKA surgeries increases from 1.2% in January 2016 to 62.4% by December 2020 Same-day volumes for THA surgery increased from 2% in January 2016 to 54.5% by December 2020. Enhanced Recovery After Surgery (ERAS) protocols have revolutionized modern anesthesia and surgery practices. Centers for Medicare Services officially removed total joint arthroplasty from the inpatient only services list, opening a new door for improved cost savings to patients and the healthcare system alike. In the post-COVID healthcare system numerous factors have pushed increasing numbers of total joint arthroplasties into the outpatient, ambulatory surgery center setting. Improved anesthesia and surgical practices in the preoperative, intraoperative, and postoperative settings have revolutionized pain control, blood loss, and ambulatory status, rendering costly hospital stays obsolete in many cases. As the population ages and more total joint procedures are performed, the door is opening for more orthopedic procedures to exit the inpatient only setting in favor of the ambulatory setting.

Comparison ultrasound-guided adductor canal block and surgeon-performed block for pain management after total knee arthroplasty: a prospective randomized controlled study

OBJECTIVE

Adductor canal block (ACB) is widely performed for postoperative analgesia for total knee arthroplasty (TKA). The aim of this study is to compare surgeon-assisted and anesthesiologist-assisted (ultrasound-guided) adductor blocks in terms of postoperative analgesic efficacy.

METHODS

This study was designed as a double-blind, prospective and randomized trial. A total of 240 participants were randomly allocated to three groups: one where the surgeon performed the adductor canal block (ACBs), another where it was conducted by an anesthetist with ultrasound guidance (ACBa), and a third group without the adductor block. The follow-up management after the Total Knee Arthroplasty (TKA) procedure occurred on the first, third, and tenth days, as well as the twelfth week. Outcome measures comprised pain assessment using the Visual Analog Scale (VAS) and monitoring opioid analgesic consumption.

RESULTS

No significant differences in demographic profiles were observed between the groups. Groups ACBa and ACBs exhibited significantly lower VAS scores compared to the control group at both 3 and 12 h after surgery, with group ACBa showing the lowest VAS scores among all groups. However, at 1 day, 3 days, 10 days and 12 weeks after surgery, there was no significant difference in VAS scores between the ACBa and ACBs groups. On the first three days, the ACBa group had the lowest opioid consumption and the lowest total opioid consumption. The differences in VAS scores between the groups began to decrease on the first day after surgery.

CONCLUSION

The adductor canal block (ACB) has been demonstrated to be an effective method of reducing pain in patients undergoing total knee replacement (TKR) in the postoperative period. Nevertheless, despite the pronounced impact that ACB performed by an anesthesiologist under ultrasound guidance has on VAS scores according to intraoperative ACB by surgeons, its effect on clinical outcomes has not been demonstrated.

TRIAL REGISTRATIONS

This study was retrospectively registered with the Clinical Trials Registry Platform on July 31, 2024 (NCT06533085).

Extended Release of Bupivacaine from Temperature-Responsive PNDJ Hydrogels Improves Postoperative Weight-Bearing in Rabbits Following Knee Surgery

Effective treatment of postoperative pain lasting for multiple days without opioids is an important clinical need. We previously reported analgesia lasting up to 96 h in a porcine soft tissue model of postoperative pain using SBG004, an extended-release formulation of bupivacaine based on the temperature-responsive polymer poly(N-isopropylacrylamide-co-dimethylbutyrolactone acrylamide-co-Jeffamine M-1000 acrylamide) [PNDJ]. Orthopaedic surgical sites such as the knee can involve complex sensory innervation which presents a distinct challenge to local anesthetic delivery. The purpose of this work was to evaluate the pharmacokinetics and efficacy of SBG004 in an orthopaedic surgical model in comparison to currently available local anesthetics. Pharmacokinetics following periarticular (PA) or intraarticular (IA) injection of SBG004 were compared against liposomal bupivacaine (Lip-Bupi) PA in New Zealand White rabbits (all doses 14.5 mg/kg). Analgesic efficacy of SBG004 (IA, PA, or IA + PA), three active comparators, and saline was evaluated following knee surgery in New Zealand White rabbits. Analgesia was assessed via weight-bearing on the operated limb during spontaneous large steps in video recordings. Systemic bupivacaine exposure lasted at least 7 days for SBG004 PA, 4 days for SBG004 IA, and 2 days for Lip-Bupi PA. In the analgesia study, weight-bearing in all active groups except SBG004 IA was more frequent versus saline through 8 h postoperatively (p < 0.05). Only SBG004 IA + PA resulted in a higher proportion of weight-bearing rabbits at 24 h versus saline (6/7 versus 2/10, p = 0.015). Analysis of pooled data from 24-72 h showed significantly greater frequency of weight-bearing in rabbits receiving SBG004 IA + PA (71%) versus saline (37%), ropivacaine cocktail (41%), and Lip-Bupi PA (36%). The results indicate that the release profile from SBG004 PA or IA coincides reasonably with the time course of postoperative pain, and SBG004 may produce longer duration of analgesia than local anesthetics currently used in knee surgery, including during the period of 24-72 h recognized as a target for extended-release local anesthetics.

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.

Analgesic Effectiveness of Liposomal Bupivacaine versus Plain Local Anesthetics for Abdominal Fascial Plane Blocks: A Systematic Review and Meta-analysis of Randomized Trials

BACKGROUND

Liposomal bupivacaine is reported to prolong the duration of analgesia when used for abdominal fascial plane blocks compared to plain local anesthetics; however, evidence from randomized trials is mixed. This meta-analysis aims to compare the analgesic effectiveness of liposomal bupivacaine to plain local anesthetics in adults receiving abdominal fascial plane blocks.

METHODS

Randomized trials comparing liposomal bupivacaine and plain (nonliposomal) local anesthetics in abdominal fascial plane blocks were sought. The primary outcome was area under the curve rest pain between 24 to 72 h postoperatively. Secondary outcomes included rest pain at individual timepoints (1, 6, 12, 24, 48, and 72 h); analgesic consumption at 0 to 24, 25 to 48, and 49 to 72 h; time to analgesic request; hospital stay duration; and opioid-related side effects. Data were pooled using the Hartung-Knapp-Sidik-Jonkman random effects method.

RESULTS

Sixteen trials encompassing 1,287 patients (liposomal bupivacaine, 667; plain local anesthetics, 620) were included. The liposomal bupivacaine group received liposomal bupivacaine mixed with plain bupivacaine in 10 studies, liposomal bupivacaine alone in 5 studies, and both preparations in 1 three-armed study. No difference was observed between the two groups for area under the curve pain scores, with a standardized mean difference (95% CI) of -0.21 cm.h (-0.43 to 0.01; P = 0.058; I2 = 48%). Results were robust to subgroup analysis based on (1) potential conflict of interest and (2) mixing of plain local anesthetics with liposomal bupivacaine. The two groups were not different for any of the day 2 or day 3 secondary outcomes.

CONCLUSIONS

This systematic review and meta-analysis suggests similar analgesic effectiveness between liposomal bupivacaine and plain local anesthetics when used for fascial plane block of the abdominal wall. The authors' analysis does not support an evidence-based preference for liposomal bupivacaine compared to plain local anesthetics for abdominal fascial plane blocks.

EDITOR’S PERSPECTIVE

Comparing Apotel and Remifentanil for Multimodal Patient-Controlled Analgesia in Postoperative Pain Management Following Total Knee Arthroplasty Surgery: A Randomized Controlled Trial

Background

Total knee arthroplasty (TKA) is a standard surgical procedure for individuals with debilitating knee arthritis. Effective postoperative pain management is essential for successful recovery, although traditional opioid-based methods have limitations.

Objectives

This study aimed to compare the efficacy of Apotel and remifentanil patient-controlled analgesia in managing postoperative pain after TKA.

Methods

This double-blind, randomized, controlled clinical trial took place at Amir-al-Momenin and Qods Hospitals in Arak, Iran, spanning from June 2022 to September 2023. Sixty-two eligible patients scheduled for knee joint replacement were randomly assigned to receive either Apotel (Group A) or remifentanil (Group R) as part of multimodal analgesia administered via a pain pump for postoperative pain relief in TKA. The study assessed hemodynamic parameters, pain levels (measured using the Visual Analog Scale), analgesic duration, and narcotic consumption. Statistical analyses were performed using SPSS v.27 and Plotly.

Results

Subjects exhibited no statistically significant differences in age, gender distribution, duration of surgery, or anesthesia. The hemodynamic status assessment in the recovery room showed no significant differences in SPO2, PR, or MAP between the groups. However, remifentanil demonstrated superior effectiveness in reducing pain over 24 hours post TKA surgery compared to Apotel, as evidenced by lower average Visual Analog Scale (VAS) scores (P < 0.001), longer duration without the need for narcotic painkillers (P < 0.001), and lower cumulative opioid analgesic consumption in Group R (P < 0.001).

Conclusions

Remifentanil demonstrates superior pain control in a multimodal pain management approach compared to Apotel, providing sustained pain reduction over 24 hours post-surgery. Moreover, remifentanil offers longer-lasting pain relief and results in lower cumulative narcotic painkiller consumption compared to Apotel.

Reduced Opioid Use Among Patients Who Received Liposomal Bupivacaine Brachial Plexus Block for Total Shoulder Arthroplasty

Purpose This retrospective cohort explores the efficacy of regional shoulder blocks using Exparel™ in patients undergoing total shoulder arthroplasty (TSA)/reverse total shoulder arthroplasty (RSA) to reduce total opioid prescription, refills, and length of stay in the acute care setting. Methods Patients who underwent TSA/RSA by a single surgeon in a three-year period were evaluated. Patients in the case group received liposomal bupivacaine 1.3% brachial plexus block while the control group received ropivacaine 0.5% interscalene brachial plexus block. Outcomes of the study included the number of opioids taken, opioids prescribed, and length of hospital stay. Results Thirty-six patients underwent TSA/RSA between January 2017 and March 2020. Patients who received an Exparel brachial plexus block had decreased opioid use within the first 24 hours after surgery compared to the ropivacaine group, 9.00 ± 14.10 and 26.20 ± 24.8 morphine milligram equivalent (MME), respectively (p=0.0213). Patients who received an Exparel brachial plexus block had decreased opioid prescriptions over the entire postoperative follow-up, 411.00 ± 200.74 MME in the case group and 593.07 ± 297.57 MME in the control group (p=0.0314). Lastly, patients who received an Exparel brachial plexus block had a shorter length of hospital stay, 1.28 ± 0.91 days as compared to the control group's 2.15 ± 1.49 days (p=0.0451). Conclusion This study demonstrates a significant reduction in opioid prescribing and use in patients who receive Exparel brachial plexus nerve blocks compared to non-liposomal local anesthetics, as well as a significant reduction in the length of hospital stay. The data suggest that Exparel use may decrease the risks associated with opioid use while providing adequate analgesia in patients undergoing shoulder arthroplasty.

Bibliometric and visual analysis of research on analgesia and total knee arthroplasty from 1990 to 2022

Background

In recent decades, there have been notable advancements in the field of analgesia and total knee arthroplasty (TKA). This study aims to employ bibliometric analysis to elucidate the prevailing research focal points and trends within analgesia and TKA from 1990 to 2022.

Material and methods

Relevant publications were retrieved from the Web of Science Core Collection. CiteSpace, VOSviewer, and Scimago Graphica were used for visualization and bibliometric analysis of countries, institutions, authors, journals, references, and keywords.

Results

A total of 2776 publications on analgesia and TKA were identified, with the United States having the highest number of publications. The University of Copenhagen was the most productive institution, and Kehlet, Henrik was the most prolific author. The Journal of Arthroplasty had the most publications and citations. The most common keywords were "TKA," "pain management," "postoperative pain," "Total hip arthroplasty (THA)," and "postoperative management." Keyword burst detection demonstrated that adductor canal block (ACB) was a recent research hotspot.

Conclusion

Our study revealed a sharp increase in global publications on analgesia and TKA, and this trend is expected to continue. Further research is necessary to determine the optimal regimen for multimodal analgesia, the ideal location and volume of ACB, and their clinical significance.

Periarticular injection, iPACK block, and peripheral nerve block in pain management after total knee arthroplasty: a structured narrative review

INTRODUCTION

Total knee arthroplasty (TKA) is commonly performed in patients with end-stage osteoarthritis or rheumatoid arthritis of the knee to reduce joint pain, increase mobility, and improve quality of life. However, TKA is associated with moderate to severe postoperative pain, which remains a significant clinical challenge. Surgeon-administered PAI and anesthesiologist-administered iPACK have proven viable alternatives to conventional peripheral nerve blocks. This review aims to discuss which IPACK block or periarticular injection, combined or not with different peripheral nerve blocks, has better effects on postoperative rehabilitation, patient satisfaction, and overall outcome.

MATERIAL AND METHODS

The literature review was performed on standards of care, current therapeutic options, a pain management protocol, and innovative treatment options for patients undergoing total knee arthroplasty. The literature was reviewed through four electronic databases: PubMed, Cochrane Library, Google Scholar, and Embase.

RESULTS

The initial search yielded 694 articles. Fifty relevant articles were selected based on relevance, recentness, search quality, and citations. Six studies compared PAI to peripheral nerve block (PNB), and eight studies checked the effectiveness of adding PNB to PAI. Three studies compared iPACK to PNB, and ten reviewed the point of adding PNB to iPACK.

CONCLUSIONS

The literature review indicates that the best analgesic effect is obtained by combining PAI or iPACK with a peripheral nerve block, particularly with ACB, due to its analgesic, motor-sparing effect, and satisfactory analgesia.

The Influence of Tourniquet and Adductor Canal Block Use on Pain and Opioid Consumption after Total Knee Arthroplasty

Reducing pain and opioid consumption after total knee arthroplasty (TKA) is an important perioperative consideration. Though commonly used, the combined influence of tourniquets and adductor canal blocks (ACBs) on pain and opioid consumption is unknown. This study evaluated inpatient opioid consumption and pain between patients with TKA based on tourniquet and/or ACB use. Pain and opioid consumption were highest when a tourniquet, but no ACB was used, and lowest when an ACB, but no tourniquet was used - though absolute differences in pain scores were not clinically significant. Tourniquet and ACB use should be considered as part of TKA opioid-sparing protocols.

Safety and Efficacy of Liposomal Bupivacaine Supraclavicular Nerve Blocks in Open Treatment of Distal Radius Fractures: A Perioperative Pain Management Protocol

INTRODUCTION

Distal radius fractures (DRFs) are common fractures requiring surgical fixation. The literature varies regarding opioid prescribing habits, opioid consumption, and postoperative pain scores. We hypothesized that the preoperative administration of a liposomal bupivacaine (LB) supraclavicular nerve block would be safe and effective in controlling postoperative pain.

METHODS

A standardized pain management protocol was implemented at a single institution from July 2021 to March 2022 for patients undergoing open reduction internal fixation of DRF. Protocol elements included a preoperative LB supraclavicular nerve block and a multimodal postoperative pain regimen. Primary clinical outcomes included postoperative pain scores and number of opioid tablets consumed.

RESULTS

Twenty patients underwent a newly implemented protocol. The average age was 56 years. Mean number of oxycodone 5-mg tablets consumed was 4.1 (median, 2.5), and mean visual analog scale pain score at first postoperative appointment was 2.8. There were no incidences of missed acute carpal tunnel postoperatively. When compared with an institutional historical control (n = 189), number of opioid pills prescribed was reduced by 60% (21.4 vs 8.6 tablets, P < 0.0001), and no patients had unscheduled health care contact because of uncontrolled pain (22% vs 0%, P < 0.016).

CONCLUSIONS

Liposomal bupivacaine supraclavicular nerve blocks are safe and effective in the treatment of postoperative pain after open reduction internal fixation of DRF. Patients consumed <5 oxycodone tablets on average, which is less than many recommend prescribed quantities (>20-30 tablets). Patients had low pain scores (2.8/10) at the first postoperative follow-up. To our knowledge, this is the first study demonstrating the utility of LB in this clinical setting.

Treatment of Acute Pain in Patients on Naltrexone: A Narrative Review

PURPOSE OF REVIEW

The tissue damage and trauma associated with surgery almost always result in acute postoperative pain. The intensity of postoperative pain can range from mild to severe. Naltrexone is suitable for patients who do not wish to be on an agonist treatment such as methadone or buprenorphine. However, naltrexone has been shown to complicate postoperative pain management.

RECENT FINDINGS

Multiple studies have found that the use of naltrexone can increase the opioid requirement for postoperative pain control. Other modalities exist that can help outside of opioids such as ketamine, lidocaine/bupivacaine, duloxetine, and non-pharmacological management can help manage pain. Multimodal pain regiments should also be employed in patients. In addition to traditional methods for postoperative pain management, other methods of acute pain control exist that can help mitigate opioid dependence and help control pain in patients who use naltrexone for their substance use disorders.

The use of liposomal bupivacaine in fracture surgery: a review

Historically, opioids have played a major role in the treatment of postoperative pain in orthopedic surgery. A multitude of adverse events have been associated with opioid use and alternative approaches to pain relief are being investigated, with particular focus on multimodal pain management regimens. Liposomal bupivacaine (EXPAREL) is a component of some multimodal regimens. This formulation of bupivacaine encapsulates the local anesthetic into a multivesicular liposome to theoretically deliver a consistent amount of drug for up to 72 hours. Although the use of liposomal bupivacaine has been studied in many areas of orthopedics, there is little evidence evaluating its use in patients with fractures. This systematic review of the available data identified a total of eight studies evaluating the use of liposomal bupivacaine in patients with fractures. Overall, these studies demonstrated mixed results. Three studies found no difference in postoperative pain scores on postoperative days 1-4, while two studies found significantly lower pain scores on the day of surgery. Three of the studies evaluated the quantity of narcotic consumption postoperatively and failed to find a significant difference between control groups and groups treated with liposomal bupivacaine. Further, significant variability in comparison groups and study designs made interpretation of the available data difficult. Given this lack of clear evidence, there is a need for prospective, randomized clinical trials focused on fully evaluating the use of liposomal bupivacaine in fracture patients. At present, clinicians should maintain a healthy skepticism and rely on their own interpretation of the available data before widely implementing the use of liposomal bupivacaine.

The Effects of Liposomal Bupivacaine on Long-term Outcomes and Decreasing Immediate Postoperative Opioid Use Following One-level and Two-level Posterior Lumbar Fusions

STUDY DESIGN

This is a retrospective observational study.

OBJECTIVE

This study aims to determine the efficacy of liposomal bupivacaine in postoperative analgesia and long-term outcomes in patients undergoing one-level and two-level posterior lumbar fusion.

SUMMARY OF BACKGROUND DATA

Multiple studies have investigated the use of liposomal bupivacaine in spine surgery with varying results. The potential benefits of its use include decreasing postoperative opioid use, improved pain control, and a shorter hospital stay. Several studies have supported its use in spine surgery with others showing minimal to no benefit. No studies have investigated its possible impact on long-term outcomes.

MATERIALS AND METHODS

A total of 42 patients (22 one-level, 20 two-level) received liposomal bupivacaine injection just before surgical closure and were compared with a historical control group of 42 patients (27 one-level, 15 two-level) that did not receive liposomal bupivacaine. Daily opioid consumption was collected and converted to oral morphine equivalents. Length of stay and daily average pain scores using the visual analog scale were also recorded. In addition, SF-36 bodily pain and physical function outcome measures were collected preoperatively and at 6 months, 1 year and 2 years postoperatively.

RESULTS

The liposomal bupivacaine group was found to have a significantly lower total opioid consumption compared with the control group ( P =0.001). The liposomal bupivacaine group was also found to use significantly fewer opioids on the day of surgery compared with the control group ( P <0.0001). There was no significant difference shown in the average visual analog scale pain scores, length of stay, or long-term outcomes between the 2 groups.

CONCLUSIONS

The use of liposomal bupivacaine in one-level and two-level posterior lumbar fusions shows promise as an adjuvant for postoperative analgesia by decreasing postoperative opioid consumption. With the varying results demonstrated with the utilization of liposomal bupivacaine in spine surgery, further investigation is warranted, namely a larger prospective randomized control study.

LEVEL OF EVIDENCE

Level III.

Liposomal Bupivacaine Versus Continuous Nerve Block: Liposomal Bupivacaine May be Non-inferior and More Cost Effective

BACKGROUND

Regional anesthesia with adductor canal block has become the standard of care for pain management after total knee arthroplasty (TKA). We hypothesized that liposomal bupivacaine (LB) may be noninferior to continuous nerve block with a pain pump in terms of average pain scores, 30- and 90-day readmissions, and emergency department (ED) visits while reducing cost.

METHODS

A retrospective chart review was performed on primary TKA patients from 2015 to 2020 by 23 orthopaedic surgeons at a single institution. The inclusion criteria was treatment with LB or a pain pump, and exclusion criteria was receipt of both anesthetics and revision surgery. A total of 2,378 patients met the inclusion criteria with 1,640 patients treated with LB and 738 treated with the pain pump. Demographic differences were not statistically significant. Primary outcomes were average pain scores, 30- and 90-day readmissions, and ED visits. Secondary outcomes were average milligram morphine equivalents per admission, hospital lengths of stay , and costs.

RESULTS

There was no significant difference in pain scores on postoperative days 0, 1, 2, or 3 (P = .77, .86, 0.08, and 0.40, respectively), 30- or 90- day readmissions (P = .527 and P = .374), ED visits (P = .129 and P = .108), milligram morphine equivalents utilizations (P = .194), or average hospital LOS (P = .348). We estimated a potential cost savings of $95 per patient and $155,800 over the course of the study.

CONCLUSION

LB was found to be noninferior to a pain pump, and the transition to this medication was associated with cost savings.

Randomized Trial of Bupivacaine Versus Liposomal Bupivacaine in Minimally Invasive Lobectomy

BACKGROUND

The objective of this single-blind randomized study is to compare local infiltration of bupivacaine or liposomal bupivacaine (LipoB) in narcotic naïve patients undergoing minimally invasive lobectomy for early stage lung cancer.

METHODS

Adult patients without previous lung surgery undergoing minimally invasive lobectomy (robotic or thoracoscopic) for early stage lung cancer were randomly assigned to bupivacaine (with epinephrine 0.25%, 1:200 000) or LipoB 1.3%. Pain level was documented using the visual analog scale and morphine equivalents for narcotic pain medications. Inhospital treatment cost and pharmacy cost were compared.

RESULTS

The study enrolled 50 patients (bupivacaine, 24; LipoB, 26). The mean age of patients was 66 years, 94% were non-Hispanic white, and 48% were male. There was no difference in baseline characteristics and comorbidities. Duration of surgery (105 vs 137 minutes, P = .152), chest tube duration (49 vs 55 hours, P = .126), and length of stay (2.45 vs 3.28 days, P = .326) were similar between treatments. Inhospital morphine equivalents were 42.7 mg vs 48 mg (P = .714), and the median pain score was 5.2 vs 4.75 (P = .602) for bupivacaine vs LipoB, respectively. There was no difference in narcotic use at 2 to 4 weeks (57.1% [12 of 21] vs 54.5% [12 of 22], P = 1.00), and at 6 months (5.9% [1 of 17] vs 9.5% [2 of 21], P = 1.00) after surgery. The overall cost ($20 252 vs $22 775, P = .225) was similar; however, pharmacy cost for LipoB was higher ($1052 vs $596, P = .0001).

CONCLUSIONS

In narcotic naïve patients undergoing minimally invasive lobectomy, short-term narcotic use, postoperative pain scores, length of stay, and long-term narcotic use were similar between bupivacaine and LipoB.

Factors contributing to 1-year dissatisfaction after total knee arthroplasty: a nomogram prediction model

Background

Identifying risk factors and early intervention are critical for improving the satisfaction rate of total knee arthroplasty (TKA). Our study aimed to identify patient-specific variables and establish a nomogram model to predict dissatisfaction at 1 year after TKA.

Methods

This prospective cohort study involved 208 consecutive primary TKA patients with end-stage arthritis who completed self-reported measures preoperatively and at 1 year postoperatively. All participants were randomized into a training cohort (n = 154) and validation cohort (n = 54). Multiple regression models with preoperative and postoperative factors were used to establish the nomogram model for dissatisfaction at 1 year postoperatively. The least absolute shrinkage and selection operator method was used to screen the suitable and effective risk factors (demographic variables, preoperative variables, surgical variable, and postoperative variables) collected. These variables were compared between the satisfied and dissatisfied groups in the training cohort. The receiver operating characteristic (ROC) curve, calibration plot, and decision curve analysis were used to validate the discrimination, calibration, and clinical usefulness of the model. Results were evaluated by internal validation of the validation cohort.

Results

The overall satisfaction rate 1 year after TKA was 77.8%. The nomogram prediction model included the following risk factors: gender; primary diagnosis; postoperative residual pain; poor postoperative range of motion; wound healing; and the rate of change in the degree of coronal lower limb alignment (hip–knee–ankle angle, HKA).The ROC curves of the training and validation cohorts were 0.9206 (95% confidence interval [CI], 0.8785–0.9627) and 0.9662 (0.9231, 1.0000) (95% CI, 0.9231, 1.0000), respectively. The Hosmer–Lemeshow test showed good calibration of the nomogram (training cohort, p = 0.218; validation cohort, p = 0.103).

Conclusion

This study developed a prediction nomogram model based on partially modifiable risk factors for predicting dissatisfaction 1 year after TKA. This model demonstrated good discriminative capacity for identifying those at greatest risk for dissatisfaction and may help surgeons and patients identify and evaluate the risk factors for dissatisfaction and optimize TKA outcomes.

Predictive Factors for Postoperative Opioid Use in Elective Skull Base Craniotomies

Objective In 2017, the United States officially declared opioid overuse a public health emergency. Due to a paucity of published benchmark data in skull base neurosurgery, we quantified postoperative opioid use in patients undergoing skull base craniotomies and identified factors that influence postoperative opioid use.

Setting Tertiary academic medical center.

Participants Patients who underwent elective craniotomies by two skull base neurosurgeons between January 2015 and May 2020.

Main Outcome Measures Demographic and perioperative data were retrospectively extracted from the electronic medical record. Surgical approaches were categorized as having either “significant” or “minimal” muscle dissection. Univariate and multivariate linear regression analyses were performed to identify predictors of postoperative opioid use at 24, 48, and 72 hours.

Results We included 300 craniotomies, 206 were supratentorial and 94 were infratentorial. This included 195 women and 105 men, with a mean age of 54.9 years. In multivariable analysis, a history of anxiety or depression, preoperative opioid use, and a history of migraines independently predicted a significantly greater opioid use at 24, 48, and 72 hours. Increased age and minimal muscle dissection independently predicted lower opioid consumption. Sex, infratentorial versus supratentorial approach, length of surgery, and postoperative steroid use did not impact total opioid use.

Conclusion Younger age, history of anxiety or depression, preoperative opioid consumption, preexisting history of migraines, and significant intraoperative muscle dissection were associated with higher postoperative opioid consumption. These risk factors provide insight on potential targets for minimizing postoperative opioids in craniotomies.

HTX-011 in Combination with Multimodal Analgesic Regimen Minimized Severe Pain and Opioid Use after Total Knee Arthroplasty in an Open-Label Study

Total knee arthroplasty (TKA) can be associated with significant postoperative pain despite multimodal analgesic (MMA) protocols, and most patients require the use of opioids postoperatively. HTX-011 is a dual-acting local anesthetic containing bupivacaine and low-dose meloxicam in an extended-release polymer. In a prior randomized controlled trial (RCT), HTX-011 reduced pain and opioid use through 72 hours after TKA compared with bupivacaine hydrochloride. This open-label study (NCT03974932) evaluated the efficacy and safety of HTX-011 combined with an MMA regimen in patients undergoing TKA under spinal anesthesia. All patients received intraoperative HTX-011 (400 mg bupivacaine/12 mg meloxicam) in combination with an MMA regimen consisting of preoperative acetaminophen, celecoxib, and pregabalin and postoperative acetaminophen and celecoxib until discharge. Opioid rescue was allowed upon patient request for additional pain control. Pain scores, opioid consumption, discharge readiness, and adverse events were recorded. Fifty-one patients were treated. Compared with the prior RCT, HTX-011 with this MMA regimen further lowered pain scores and reduced opioid use. Mean patient-reported pain scores remained in the mild range, and 82% of patients or more did not experience severe pain at any individual time point through 72 hours after surgery. Mean total opioid consumption was low over 72 hours: 24.8 morphine milligram equivalents (1-2 tablets of oxycodone 10 mg/day). Approximately 60% of patients were ready for discharge by 12 hours, and 39% were discharged without an opioid prescription and did not call back for pain management. The treatment regimen was well tolerated, and no added risk was observed with the addition of MMA. HTX-011 with an MMA regimen reduced postoperative pain and opioid use following TKA.

Will the Use of Intraoperative Liposomal Bupivacaine During Thumb Carpometacarpal Arthroplasty Decrease Postoperative Use of Opioids? A Prospective Randomized Study

PURPOSE

This study evaluated the use of intraoperative local injection of liposomal bupivacaine to decrease opioid use in the early postoperative period for patients undergoing outpatient thumb carpometacarpal joint arthroplasty.

METHODS

A prospective, randomized, controlled, single-blinded study was designed to compare 2 groups of patients for opioid use, pain scores, and nonopioid pill consumption within 5 days after surgery. The investigational group received an intraoperative injection of 10 ml (133 mg) liposomal bupivacaine. The control group received no local anesthetic. All patients were anesthetized with a standardized supraclavicular nerve block and were prescribed equal amounts of oral narcotic analgesic. Outcomes were assessed by collecting the data from postoperative patient-reported diaries.

RESULTS

The experimental group reported a significantly lower total opioid consumption for the 5 days after surgery. Daily opioid use, as measured by both opioid pill equivalent count and morphine milligram equivalent in addition to postoperative pain scores and nonopioid pill consumption, was not different between groups.

CONCLUSIONS

Intraoperative injection of liposomal bupivacaine was shown to decrease total opioid intake during the 5 days after thumb carpometacarpal arthroplasty.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic II.

Micro- and nanocarriers for pain alleviation

Acute or chronic pain is a major source of impairment in quality of life and affects a substantial part of the population. To date, pain is alleviated by a limited range of treatments with significant toxicity, increased risk of misuse and inconsistent efficacy, owing, in part, to lack of specificity and/or unfavorable pharmacokinetic properties. Thanks to the unique properties of nanoscaled drug carriers, nanomedicine may enhance drug biodistribution and targeting, thus contributing to improved bioavailability and lower off-target toxicity. After a brief overview of the current situation and the main critical issues regarding pain alleviation, this review will examine the most advanced approaches using nanomedicine of each drug class, from the preclinical stage to approved nanomedicines.

Efficacy of Liposomal Bupivacaine and Bupivacaine Hydrochloride vs Bupivacaine Hydrochloride Alone as a Periarticular Anesthetic for Patients Undergoing Knee Replacement: A Randomized Clinical Trial

Question

Among patients undergoing knee replacement surgery, does liposomal bupivacaine and bupivacaine hydrochloride administered at the surgical site improve postoperative recovery at 72 hours and postoperative pain from 6 to 72 hours compared with bupivacaine hydrochloride alone?

Findings

In this randomized clinical trial of 533 patients undergoing knee replacement surgery, no difference in the coprimary outcomes of Quality of Recovery 40 score at 72 hours or pain visual analog scale score area under the curve from 6 to 72 hours was detected between patients receiving liposomal bupivacaine and bupivacaine hydrochloride and those receiving bupivacaine hydrochloride alone. In addition, liposomal bupivacaine was not found to be cost-effective.

Meaning

This study found that liposomal bupivacaine did not improve postoperative recovery or pain compared with bupivacaine hydrochloride alone among patients undergoing knee replacement surgery.

Importance

More than half of patients who undergo knee replacement surgery report substantial acute postoperative pain.

Objective

To evaluate the efficacy and cost-effectiveness of periarticular liposomal bupivacaine for recovery and pain management after knee replacement.

Design, Setting, and Participants

This multicenter, patient-blinded, pragmatic, randomized clinical superiority trial involved 533 participants at 11 institutions within the National Health Service in England. Adults undergoing primary unilateral knee replacement for symptomatic end-stage osteoarthritis were enrolled between March 29, 2018, and February 29, 2020, and followed up for 1 year after surgery. Follow-up was completed March 1, 2021. A per-protocol analysis for each coprimary outcome was performed in addition to the main intention-to-treat analysis.

Interventions

Two hundred sixty-six milligrams of liposomal bupivacaine admixed with 100 mg of bupivacaine hydrochloride compared with 100 mg of bupivacaine hydrochloride alone (control) administered by periarticular injection at the time of surgery.

Main Outcome and Measures

The coprimary outcomes were Quality of Recovery 40 (QoR-40) score at 72 hours and pain visual analog scale (VAS) score area under the curve (AUC) from 6 to 72 hours. Secondary outcomes included QoR-40 and mean pain VAS at days 0 (evening of surgery), 1, 2, and 3; cumulative opioid consumption for 72 hours; functional outcomes and quality of life at 6 weeks, 6 months, and 1 year; and cost-effectiveness for 1 year. Adverse events and serious adverse events up to 12 months after randomization were also assessed.

Results

Among the 533 participants included in the analysis, the mean (SD) age was 69.0 (9.7) years; 287 patients were women (53.8%) and 246 were men (46.2%). Baseline characteristics were balanced between study groups. There was no difference between the liposomal bupivacaine and control groups in QoR-40 score at 72 hours (adjusted mean difference, 0.54 [97.5% CI, −2.05 to 3.13]; P = .64) or the pain VAS score AUC at 6 to 72 hours (−21.5 [97.5% CI, −46.8 to 3.8]; P = .06). Analyses of pain VAS and QoR-40 scores demonstrated only 1 statistically significant difference, with the liposomal bupivacaine arm having lower pain scores the evening of surgery (adjusted difference −0.54 [97.5% CI, −1.07 to −0.02]; P = .02). No difference in cumulative opioid consumption and functional outcomes was detected. Liposomal bupivacaine was not cost-effective compared with the control treatment. No difference in adverse or serious adverse events was found between the liposomal bupivacaine and control groups.

Conclusions and Relevance

This study found no difference in postoperative recovery or pain associated with the use of periarticular liposomal bupivacaine compared with bupivacaine hydrochloride alone in patients who underwent knee replacement surgery.

Trial Registration

isrctn.com Identifier: ISRCTN54191675

Liposomal Bupivacaine and Ropivacaine Adductor Canal Blocks for Anterior Cruciate Ligament Reconstruction Provide Similar Postoperative Analgesia

The purpose of this study was to compare postoperative pain following anterior cruciate ligament (ACL) reconstruction (ACLR) in patients receiving an adductor canal block (ACB) with ropivacaine (R-ACB) or liposomal bupivacaine (LB-ACB). The secondary purpose was to compare opioid consumption. A prospective cohort study of patients undergoing ACLR at an academic medical center was conducted from November 1, 2018 to November 21, 2019. The first cohort received R-ACB and 30 tablets of 5/325 mg oxycodone/acetaminophen. After June 13, 2019, the second cohort received LB-ACB and 20 tablets of 5/325 mg oxycodone/acetaminophen with the reduction in opioids prescribed resulting from a hospital quality improvement initiative to decrease narcotic consumption. From postoperative days 0 through 6, pain was assessed thrice daily using a numeric rating scale. Total postoperative opioid consumption was reported via tablet count and converted to oral morphine equivalents (OMEs). During this period, 165 subjects underwent ACLR, and 126 met the eligibility criteria (44.4% female, 55.6% male; mean ± standard deviation: 28.7 ± 13.7 years). Sixty-six (52.4%) received LB-ACB, and 60 (47.6%) received R-ACB (p = 0.53). The most common graft utilized was quadriceps autograft (63.6% LB-ACB; 58.3% R-ACB, p = 0.76). Mean postoperative pain scores were similar between groups during the entire postoperative period (p ≥ 0.08 for POD 0-6). While postoperative opioid consumption was lower among patients receiving LB-ACB (median OME [interquartile range]: 28.6 [7.5-63.8] vs. 45.0 [15.0-75.0], p = 0.023), this only amounted to an average of 2.2 tablets. Patients receiving LB-ACB in the setting of ACLR reported similar postoperative pain compared with those receiving R-ACB. Despite the second aim of our study, we cannot make conclusions about the effect of each block on opioid consumption given that each cohort received different numbers of opioid tablets due to institutional pressure to reduce opioid prescribing. As few patients completed their opioid prescriptions or requested refills, further reduction in prescription size is warranted. Future studies are necessary to further elucidate the effect of LB-ACB versus R-ACB on postoperative pain and opioid consumption after ACLR.

Impact of Liposomal Bupivacaine on Post-Operative Pain and Opioid Usage in Thyroidectomy

OBJECTIVES

Opioid analgesia has been integral in post-operative pain control for decades. The over-prescription of opioids, commonly in the surgical patient, has contributed to the current opioid epidemic. Liposomal bupivacaine (LB), a long-acting analgesia formulation, has demonstrated decreased post-operative pain and opioid requirements in patients treated across multiple surgical subspecialties. The aims of this retrospective study are to assess post-operative pain and opioid use in patients who received LB at the time of thyroidectomy.

METHODS

A cohort-matched retrospective review of patients who underwent thyroidectomy by 2 surgeons between January 2010 and December 2019 was performed. Patients were divided into those that received LB intraoperatively and those that did not. Statistical analyses were performed using the Chi-square or Fisher's exact test, and 2-sample T-test or Wilcoxon rank sum test.

RESULTS

Of the 201 patients included in this study, 113 patients received LB and 88 did not. Patients who received LB had a lower median visual analog scale (VAS) pain score (2 vs 3, P = .2252), lower maximum VAS pain score (6 vs 7, P = .0898), were less likely to require opioid medications (73.5% vs 85.2%, P = .0434), and had a lower percentage of daily morphine milligram equivalent value ≥45 (89.8% vs 95.3%, P = .1581) during the post-operative period when compared to those that did not.

CONCLUSION

This study suggests a role for incisional infiltration with LB for post-operative pain management in patients undergoing transcervical thyroidectomy. We report reduced post-operative pain scores and opioid analgesia requirements in patients who received LB.

Intraoperatively local infiltration anesthesia in hemiarthroplasty patients reduces the needs of opioids: a randomized, double-blind, placebo-controlled trial with 96 patients in a fast-track hip fracture setting

Background and purpose - Local infiltration analgesia (LIA) is commonly used as a component in multimodal analgesia. Pain management directed towards hip fracture patients operated on with hemiarthroplasty is often based on knowledge regarding pain treatment following elective surgery. In this elderly patient population, it is of value to clarify whether adding local infiltration analgesia (LIA) to the postoperative analgesic regimen might reduce postoperative pain or have an opioid-reducing effect. Patients and methods - 96 hip fracture patients undergoing hemiarthroplasty in spinal anesthesia were included. All patients received a multimodal pain regimen and were randomized to receive either ropivacaine or placebo. All patients received morphine depot-opioid and morphine as rescue medication postoperatively. The primary endpoint was pain during mobilization in the recovery unit on the day of surgery. Secondary endpoints were pain during mobilization the day after surgery and postoperative opioid requirements on the first postoperative day. Results - The levels of pain (NRS) during mobilization both in the recovery unit and on the day after surgery were similar in the 2 groups, with median 4 and 0.5 in the placebo group and median 3.5 and 1 in the ropivacaine group respectively. Total consumption of opioids on day 0 and day 1 were 4.6 mg lower in the ropivacaine group (p = 0.04). Pain during mobilization was registered for only 44 of 96 patients for several reasons, including lack of mobilization. Interpretation - There were similar pain scores in both the local infiltration and placebo group postoperatively. However, substantially reduced opioid consumption was found in patients receiving LIA.

Liposomal Bupivacaine vs Ropivacaine for Adductor Canal Blocks in Total Knee Arthroplasty: A Prospective Randomized Trial

BACKGROUND

The purpose of this study is to determine the benefit of the analgesic liposomal bupivacaine compared to ropivacaine, by assessing pain and joint stiffness, and total oral opioid consumption by milligram morphine equivalent (MME) after total knee arthroplasty.

METHODS

Patients were randomized to receive either the study drug (liposomal bupivacaine admixed with bupivacaine) or the control drug (ropivacaine) in an adductor canal block. Only the anesthesiologist performing the block was aware of which arm of the study the patient was randomized to. MME, pain, Knee injury and Osteoarthritis Outcome Score Joint Replacement, and overall benefit of analgesia scores were recorded 24, 48, and 72 hours post-surgery either face-to-face or via telephone depending on patient discharge status.

RESULTS

One hundred patients were enrolled into the study and analyzed: 54 in the control group and 46 in the experimental group. Primary outcomes measured were pain as a numerical rating scale, MME, and length of stay in hours. Secondary outcomes were joint pain and stiffness recorded as Knee injury and Osteoarthritis Outcome Score Joint Replacement outcome and overall benefit of analgesia score. No statistically significant between-group differences were observed for any measured outcome.

CONCLUSION

We did not find any supporting evidence that liposomal bupivacaine yields increased pain relief following total knee arthroplasty compared to the control drug, ropivacaine.

Emerging drugs for the treatment of postsurgical pain

INTRODUCTION

Postoperative pain is a distressful experience and remains to be a significant concern after surgery. Current agents either fail to prevent or minimize postoperative pain or cause a series of adverse effects, addiction, or abuse. Opioids have been the gold standard in the treatment of postoperative pain despite their well-described adverse effects. Many new agents with different mechanisms of action have been recently introduced to address this issue.

AREAS COVERED

This current review summarizes the list of new and emerging drugs investigated for their efficacy in controlling the postoperative pain and decreasing the need for rescue opioid use, adverse effect profile, abuse, and addiction potential.

EXPERT OPINION

Opioids have unrivaled analgesic efficacy. However adverse effects of opioids led to the search for better options. In mild pain most of the emerging drugs have been shown to control postoperative pain and decrease the use of rescue opioid, however fail to control pain after major surgeries causing severe pain. Specific agents such as Oliceridine, new local anesthetics, etc., are effective in controlling severe pain and hold a promise to replace opioids in the near future.

Comparison between Local Infiltration Analgesia and Ultrasound Guided Single Shot Adductor Canal Block Post Total Knee Replacement Surgery - A Randomized Controlled Trial

Context:

Good quality analgesia posttotal knee arthroplasty (TKA) contributes majorly to early mobilization and shorter hospital stay.

Aim:

To compare adductor canal block (ACB) versus local infiltration analgesia (LIA) for postoperative pain relief in patients undergoing TKA.

Settings and Design:

This prospective, single-blind, randomized controlled trial was undertaken at a tertiary care university hospital.

Materials and Methods:

Sixty patients of American Society of Anesthesiologists physical status Classes I, II, and III, who received spinal anesthesia for TKA were randomly allocated to two groups. Group A patients had LIA of the knee joint using a mixture of 50 mL of 0.25% bupivacaine, 10 mg morphine (1 mL) and 99 mL of normal saline. Group B patients received ACB using 25 mL of 0.5% bupivacaine under ultrasound guidance. All patients received multimodal analgesia comprising of paracetamol, diclofenac, and patient controlled analgesia with morphine in the first 24 h' postoperative period. The primary outcome measures were first 24 h' morphine consumption and pain scores at 4, 6, 8, 12, and 24 h. The secondary outcome measures were nausea/vomiting, sedation, and patient satisfaction scores.

Statistical Analysis:

Statistical analysis was performed using the Student's t-test, Mann–Whitney test, and Chi-square test.

Results:

The 24 h morphine consumption was 11.97 ± 7.97 and 10.83 ± 6.41 mg in the LIA group and ACB group, respectively (P = 0.54). No significant differences were noted either in the pain scores at rest and flexion or secondary outcome measures between both groups in the first 24 h.

Conclusion:

Single-shot ACB is equally effective as LIA as postoperative analgesia for TKA.

Preoperative characteristics and intraoperative factors do not correlate with accomplishments of active straight-leg raising, standing up, and walking after primary total knee arthroplasty

Background

The correlations between patient characteristics and early postoperative functional performances after total knee arthroplasty have not been adequately studied. The purpose of this study was to clarify the effects of preoperative characteristics (sex, age, body mass index, American Society of Anesthesiologists grade, hospital for special surgery score) and intraoperative factors (duration of surgery and tourniquet use) on the time required to accomplish active straight-leg-raising, standing up, and walking as the objective performances for the initiation of early postoperative rehabilitation.

Methods

This cross-sectional retrospective study included 307 patients (384 primary total knee arthroplasties). Postoperative times required until each activity was accomplished were measured. Various preoperative characteristics and intraoperative factors that might affect three objective performances were evaluated.

Results

The postoperative times required before each activity was accomplished were 1.5 ± 0.5 days for active straight-leg-raising, 1.2 ± 0.5 days for standing up, and 1.4 ± 0.7 days for walking. There were no significant correlations between any factor (age, body mass index, hospital for special surgery score, duration of surgery, and tourniquet use) and the three objective performances using Spearman’s correlation coefficient. There were no differences in sex or American Society of Anesthesiologists grade for three objective functional assessments by Wilcoxon rank sum test.

Conclusions

Differences in patient preoperative characteristics and intraoperative factors are unlikely to affect three objective functional performances in the early postoperative period. Therefore, there is no need to consider differences between patients when initiating early postoperative rehabilitation.

Ultrasound-guided genicular nerves block: an analgesic alternative to local infiltration analgesia for total knee arthroplasty: A noninferiority, matched cohort study

BACKGROUND

Standard analgesic strategies for total knee arthroplasty employ local infiltration analgesia. Blockade and radiofrequency ablation of the genicular nerves are effective treatments for patients with chronic pain because of knee osteoarthritis.

OBJECTIVE

To test the noninferiority of the analgesic effect of genicular nerves block in comparison with local infiltration analgesia after 24 h of total knee arthroplasty.

DESIGN

Prospective cohort study.

SETTING

Perioperative setting.

PATIENTS

Thirty-five patients scheduled for total knee arthroplasty were prospectively included in the study and compared with 35 patients in a retrospective cohort.

INTERVENTION

Genicular nerve blocks in the prospective cohort were compared with local infiltration analgesia in the retrospective cohort.

MAIN OUTCOME MEASURES

The pain numeric rating scale and the cumulative opioid consumption in oral morphine equivalents during the first 24 h.

RESULTS

We conducted propensity score-matched analyses of patients using acute postoperative pain-related risk covariates. After one-to-one propensity score matching, 21 patients were included in the local infiltration analgesia group and 21 in the genicular nerve block group. The median difference in numeric rating score at rest at 24 h was -0.99 [95% confidence interval (CI), -1.99 to 0.5, P = 0.012] on the unmatched cohort and -1.9 (95% CI, -2 to 0, P = 0.002) on the matched cohort (meeting the noninferiority criteria, Δ=1). The median difference in cumulative opioid consumption was 2.5 mg (95% CI, -13.5 to 2.5, P < 0.001) for the unmatched cohort and 4.99 mg (95% CI, -11.5 to 2.5, P < 0.001) on the matched group (meeting the noninferiority criteria, Δ = 21 mg).

CONCLUSION

Local infiltration analgesia and genicular nerve block are comparable in terms of analgesic results. Therefore, genicular nerves block is an alternative to local infiltration analgesia in patients undergoing total knee arthroplasty.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT04024319.

Perioperative Management in Reverse Total Shoulder Arthroplasty

PURPOSE OF REVIEW

A successful reverse total shoulder arthroplasty requires careful preoperative planning and perioperative management. Preoperative comorbidity risks, perioperative pain management, and postoperative rehabilitation are all critical components of this arthroplasty. The current review examines available literature to guide the perioperative care of the reverse total shoulder arthroplasty patient.

RECENT FINDINGS

One of the most important advances for shoulder arthroplasty in recent years has been heightened awareness of various modalities for perioperative pain management. A number of recent studies have focused on the options for regional blockade as a critical tool for postoperative pain relief and the use of either continuous interscalene blocks or single shot blocks are supported. Additional studies are necessary to define the best local anesthetic agent and delivery mechanism to provide appropriate pain relief with a low side effect profile. Management of the patient throughout the perioperative course is a critical component in achieving better patient outcomes delivering high quality patient care. An orthopedic surgery team focused on perioperative management is better positioned to decrease adverse events and improve patient outcomes after reverse total shoulder arthroplasty.

Reduced Opioid Use Among Patients Who Received Liposomal Bupivacaine for ACL Reconstruction

Standard multimodal pain management for anterior cruciate ligament reconstruction typically includes a combination of local anesthetics, nonsteroidal anti-inflammatory drugs, and opioids. Opioids present a substantial risk, and there is a rising number of prescription opioid-related overdoses in the United States. The goal of this study was to evaluate the quantity of opioids prescribed to patients who received liposomal bupivacaine as a component of their multi-modal pain regimen. The electronic medical records of patients who underwent anterior cruciate ligament reconstruction by a single surgeon at an urban hospital during a 2-year period were evaluated. Patients in the case group received liposomal bupivacaine and those in the control group did not. Statistical analysis of the number of pills prescribed and numeric pain rating scale scores was performed with a 2-tailed unequal variance t test. Statistical analysis of opioid prescription refills was performed with a chi-square test. A total of 67 patients were included. The mean number of 5-mg oxycodone tablets prescribed to the case group (9.29±10.29 tablets) was significantly lower (P<.01) compared with the number prescribed to the control group (66.26±37.13 tablets). Patients in the case group also were less likely to require an opioid prescription refill at the first follow-up appointment (P<.01; absolute risk reduction, 50%; number needed to treat, 2). Mean numeric pain rating scale score at 2 weeks was 2.8±2.1 in the case group and 3.8±2.4 in the control group (P=.09). Patients who received liposomal bupivacaine as part of multimodal pain management had significantly fewer opioid prescriptions. Despite the reduction in opioids prescribed, patients in the case group only showed a trend toward a reduction in pain at 2-week follow-up. [Orthopedics. 2021;44(2):e229-e235.].

Does Local Administration of Liposomal Bupivacaine Reduce Pain and Narcotic Consumption in Adult Spinal Deformity Surgery?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine if local administration of liposomal bupivacaine (LB) reduces postoperative pain scores and narcotic use in spinal deformity patients.

METHODS

Adult patients undergoing elective spinal fusion (7 or more levels) for scoliosis or kyphosis were selected for inclusion. Patients received either periincisional injections of combined liposomal and standard bupivacaine (n = 90, group L) or standard bupivacaine only (n = 69, group C). Perioperative pain scores (VAS [visual analogue scale]), opioid use, length of stay, functional outcome (ODI [Oswestry Disability Index]), and perioperative complications were recorded. No external funding was received for this study.

RESULTS

A total of 159 patients met inclusion criteria (mean age was 54.2 years of age). No significant baseline demographic differences were noted between the 2 groups. Group L experienced slight improvements in pain control on postoperative day (POD) 1 (P = .02). No difference in pain scores were otherwise noted. Group L transitioned off of intravenous (IV) narcotics faster with 52.6% less IV use by POD3 (P = .03). No differences in total narcotic consumption, perioperative complications, lengths of stay, and functional outcome scores were otherwise noted between the 2 cohorts.

CONCLUSIONS

The use of LB in adult spinal deformity surgery does not appear to provide clinically important improvements in postoperative pain at the manufacturer's recommended dosage. Furthermore, while patients receiving LB may transition more quickly off of IV narcotics, this does not appear to translate into an overall decrease in narcotic consumption, hasten return of bowel function, or decrease hospital lengths of stay. Future prospective randomized control trials are warranted. The use of varying dosages of LB may also help further clarify the true efficacy of LB in the setting of spinal deformity surgery.

Adductor Canal Block vs Liposomal Bupivacaine Periarticular Injection in Total Knee Arthroplasty: A Randomized Controlled Trial

BACKGROUND

This study compares postoperative pain scores and functional outcomes between liposomal bupivacaine peri-articular injection (LB-PAI) vs a single-shot adductor canal block (ACB) using bupivacaine HCl in patients undergoing primary total knee arthroplasty (TKA).

METHODS

This is a randomized controlled trial of 56 patients who were treated with TKA for arthritis. Patients were randomized to receive an intraoperative LB-PAI (n = 27) or preoperative ACB using bupivacaine HCl (n = 29). Both groups were otherwise given our institutional standard multimodal pain protocol. Data on Visual Analog Scale (VAS) pain scores, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, knee range of motion, postoperative ambulation distance, hospital length of stay, and opioid use were collected. The total cost of each intervention was compared at the conclusion of the study.

RESULTS

Age, gender, or body mass index was similar between groups. Compared to the ACB group, the LB-PAI group trended to lower average VAS pain scores on postoperative days 0, 1, and 2 (average difference [95% confidence interval] = -0.5 [-0.7, 1.7], -1.0 [-0.1, 2.0], -0.2 [-0.8, 1.3]), and identical average VAS pain scores on postoperative days 4 and 7. These differences and all postoperative outcome measures were not statistically significant at any time point. A single 266-milligram vial of liposomal bupivacaine costs $351, and a single-shot ACB costs $893 at our institution.

CONCLUSIONS

This randomized controlled trial shows similar postoperative pain control, functional outcomes, and opioid use between LB-PAI and a single-shot ACB in patients undergoing primary TKA. However, the single-shot ACB costs $542 more than the LB-PAI at our institution.

Reduction of Opioid Use With Enhanced Recovery Program for Total Knee Arthroplasty

Background

Adequate pain control after total knee arthroplasty (TKA) is critically important to achieve early mobilization, shorten the length of hospital stay, and reduce postoperative complications. At Veterans Affairs North Texas Health Care System (VANTHCS) in Dallas, we implemented a multidisciplinary enhanced recovery after surgery (ERAS) protocol to deal with increasing length of stay and postoperative pain. We hypothesize that this protocol will reduce the overall opioid burden and decrease inpatient hospital length of stay in our TKA population.

Methods

A retrospective review of all TKAs performed by a single surgeon at VANTHCS from 2013 to 2018 was conducted. A postoperative ERAS protocol was implemented in 2016. We compared perioperative opioid use and LOS between cohorts before and after protocol implementation.

Results

Inpatient length of stay between cohorts was reduced from 66.8 hours for the standard of care (SOC) period to 22.3 hours in the ERAS cohort. Inpatient opioid use measured by total oral morphine equivalent doses averaged 169.5 mg and 66.7 mg for SOC and ERAS cohorts, respectively (P = .0001). Intraoperative use of opioids decreased from 57.4 mg in the SOC cohort to 10.5 mg in the ERAS cohort (P = .0001). Postanesthesia care unit (PACU) opioid use decreased from 13.6 mg (SOC) to 1.3 mg (ERAS) (P = .0002). There was no significant difference in complications between cohorts (P = .09).

Conclusions

Initiating a multidisciplinary ERAS protocol for TKA at VANTHCS significantly reduced inpatient length of stay and perioperative opioid use with no deleterious effects on complication rates. The ERAS protocol has major medical and financial implications for our unique VA population and the VA health care system.

Effectiveness of Liposomal Bupivacaine Compared With Standard- of-Care Measures in Pediatric Cardiothoracic Surgery: A Retrospective Cohort Study

OBJECTIVE

Effective postsurgical pain management is important for pediatric patients to improve outcomes while reducing resource use and waste. The authors examined opioid consumption and economic outcomes associated with liposomal bupivacaine (LB) or non-LB analgesia use in pediatric patients undergoing cardiothoracic surgery.

DESIGN

The authors retrospectively analyzed Premier Healthcare Database records.

SETTING

The data extracted from the database included patient records from hospitals across the United States in both rural and urban locations.

PARTICIPANTS

The records included data from patients aged 12-to-<18 years.

INTERVENTIONS

The records belonged to patients undergoing video-assisted thoracoscopic procedures (VATS) who received LB or non-LB analgesia after surgery.

MEASUREMENTS AND MAIN RESULTS

Outcomes included in-hospital postsurgical opioid consumption in morphine milligram equivalents (MMEs), hospital length of stay (LOS), and total hospital costs; the LB and non-LB cohorts were compared using a generalized linear model with inverse probability of treatment weighting to balance the cohorts. For VATS procedures, pediatric patients receiving LB had significant reductions in in-hospital opioid consumption (632 v 991 MMEs; p < 0.0001), shorter LOS (5.1 v 5.6 days; p = 0.0023), and lower total hospital costs ($18,084 v $21,962; p < 0.0001) compared with those receiving non-LB analgesia.

CONCLUSIONS

These results support use of LB in multimodal analgesia regimens for managing pain in pediatric patients after cardiothoracic surgery.

The Efficacy of Liposomal Bupivacaine for Opioid and Pain Reduction: A Systematic Review of Randomized Clinical Trials

Background The opioid crisis has prompted surgeons to search for alternative postoperative methods of analgesia. Liposomal bupivacaine is a long-acting local anesthetic formulation used for pain, potentially reducing opioid use. Evaluation of liposomal bupivacaine as a viable alternative for pain management is needed. The objective was to assess the efficacy of randomized clinical trials (RCTs) of liposomal bupivacaine in postoperative pain management and opioid consumption. Material and Methods The authors extracted RCTs comparing liposomal bupivacaine versus placebo or active comparators for postoperative pain or opioid reduction from PubMED/MEDLINE, Cochrane Library, and ClinicalTrials.gov. Exclusion criteria included nonhuman studies, non-RCTs, pooled studies, and inability to access full text. The following variables were abstracted: surgical specialty, number of subjects, pain and opioid outcomes, and authors' financial conflicts of interest. Results We identified 77 published RCTs, of which 63 studies with a total of 6770 subjects met inclusion criteria. Liposomal bupivacaine did not demonstrate significant pain relief compared to placebo or active agents in 74.58% of RCTs. Of the studies evaluating narcotic use, liposomal bupivacaine did not show a reduction in opioid consumption in 85.71% of RCTs. Liposomal bupivacaine, when compared to standard bupivacaine or another active agent, yielded no reduction in opioid use in 83.33% and 100.00% of studies, respectively. Clinical trials with a financial conflict of interest relating to the manufacturer of liposomal bupivacaine were significantly more likely to show pain relief (OR: 14.31 [95% CI, 2.8, 73.10], P = 0.0001) and decreased opioid consumption (OR: 12.35 [95% CI 1.40, 109.07], P = 0.0237). Of the 265 unpublished RCTs on ClinicalTrials.gov, 47.54% were withdrawn, terminated, suspended, or completed without study results available. Conclusions The efficacy of liposomal bupivacaine for providing superior postoperative pain control relative to placebo or another active agent is not supported by a majority of RCTs. Underreporting of trial results and bias due to underlying financial relationships amongst authors are two major concerns that should be considered when evaluating the available evidence.

Liposomal bupivacaine interscalene nerve block in shoulder arthroplasty is not superior to plain bupivacaine: a double-blinded prospective randomized control trial

BACKGROUND

Interscalene brachial plexus blocks are a common modality used to provide adjunctive pain relief with shoulder replacement surgery. In 2018, the Federal Drug Administration approved the use of liposomal bupivacaine (LB) for such nerve blocks. We sought to evaluate whether this formulation of bupivacaine would provide superior pain relief for shoulder replacement patients over standard bupivacaine alone. Our hypotheses were that in the LB cohort the average postoperative pain score over the first 72 hours would be significantly lower, time to block cessation would be longer, total opioid consumption would be lower, and the average patient satisfaction score regarding their pain management would be higher.

MATERIALS AND METHODS

A randomized, double-blinded study was designed comparing primary shoulder replacement surgery after an interscalene block with 25 mL of 0.5% plain bupivacaine vs. 133 mg of LB with 7.5 mL of 0.5% and 7.5 mL of 0.25% plain bupivacaine. A total of 104 patients were included in the study, with an equal number in each study arm. Patients' visual analog pain scores (VAPS) were followed for their inpatient stay, first 3 full outpatient days, and at a 3-week follow-up. Use of opioid medication was recorded for the same intervals and converted to morphine milligram equivalents. The time to first opioid rescue was documented, as well as the patients' satisfaction with their pain management at both the 3-day and 3-week intervals.

RESULTS

No clinically relevant advantage to the use of LB over plain bupivacaine was found. During the second postoperative day, the mean VAPS was 2.4 with LB vs. 3.3 in the standard cohort (P = .0409). The only other statistically significant finding was a higher VAPS with LB during the third full day home compared with standard bupivacaine (4.0 vs. 2.8, respectively, P = .0197). Both of these differences were less than the minimal clinically important difference of 2 for the VAPS. Analysis of the VAPS for the first and third postoperative days, the first and second full days home, and at 3 weeks revealed no significant difference. Similarly, there was no significant difference in time to first opioid rescue, total morphine milligram equivalent use, and patient satisfaction with pain management.

CONCLUSION

When used for an interscalene block to provide adjunctive pain relief in shoulder replacement surgery, the addition of LB to plain bupivacaine provides no additional clinically important benefit to the patient's pain experience over standard bupivacaine.

Narcotic-Free Perioperative Total Knee Arthroplasty: Does the Periarticular Injection Medication Make a Difference?

Multimodal pain management strategies are critical in total knee arthroplasty (TKA). There has recently been a shift toward opioid sparing protocols, yet most publications continue to use narcotics in the perioperative period. Periarticular injections are a popular adjunct but studies regarding the optimal medications have high variability making it difficult to choose the optimal medication. The purpose of this study is to validate a perioperative, opioid-free protocol and compare two different periarticular injections without the variability in previous reports. A multimodal pain protocol was instituted that administered no narcotic medications in the perioperative period. Over 2 years, primary TKA patients were informally randomized to receive liposomal bupivacaine (LB), or a cocktail of medications (CO). A total of 189 patients were included: 101 patients in group LB and 88 patients in group CO. Postoperative opioid consumption, length of stay, and inpatient distance ambulated were compared across the two injection groups. In morphine milligram equivalents, group LB consumed a mean of 20.36 mg of oxycodone versus 23.18 mg in group CO (p = 0.543). For tramadol, group LB consumed 27.24 mg versus 28.69 mg in group CO (p = 0.714). Mean hospital stay was 1.70 days for group LB and 1.72 days for group CO (p = 0.811). Distance ambulated was 528.4ft for group LB and 499.8ft for group CO (p = 0.477). In the LB group, 50% of patients required no oxycodone, and 12% of them took neither oxycodone nor tramadol for pain. In the CO group, 40% declined oxycodone and 10% declined both oxycodone and tramadol. We successfully treated all patients without narcotic medications in the perioperative period. Although we saw trends for improvements in group LB, these were small and not clinically meaningful. It appears that both injections were effective. There is a significant cost difference and medications should be chosen based on surgeon preference and institutional needs.

Perineural Liposomal Bupivacaine Is Not Superior to Nonliposomal Bupivacaine for Peripheral Nerve Block Analgesia

BACKGROUND

Liposomal bupivacaine is purported to extend analgesia of peripheral nerve blocks when administered perineurally. However, evidence of the clinical effectiveness of perineural liposomal bupivacaine is mixed. This meta-analysis seeks to evaluate the effectiveness of perineural liposomal bupivacaine in improving peripheral nerve block analgesia as compared with nonliposomal local anesthetics.

METHODS

The authors identified randomized trials evaluating the effectiveness of peripheral nerve block analgesic that compared liposomal bupivacaine with nonliposomal local anesthetics. The primary outcome was the difference in area under the receiver operating characteristics curve (AUC) of the pooled 24- to 72-h rest pain severity scores. Secondary outcomes included postoperative analgesic consumption, time to first analgesic request, incidence of opioid-related side effects, patient satisfaction, length of hospital stay, liposomal bupivacaine side effects, and functional recovery. AUC pain scores were interpreted in light of a minimal clinically important difference of 2.0 cm · h.

RESULTS

Nine trials (619 patients) were analyzed. When all trials were pooled, AUC pain scores ± SD at 24 to 72 h were 7.6 ± 4.9 cm · h and 6.6 ± 4.6 cm · h for nonliposomal and liposomal bupivacaine, respectively. As such, perineural liposomal bupivacaine provided a clinically unimportant benefit by improving the AUC (95% CI) of 24- to 72-h pain scores by 1.0 cm · h (0.5 to 1.6; P = 0.003) compared with nonliposomal bupivacaine. Excluding an industry-sponsored trial rendered the difference between the groups nonsignificant (0.7 cm · h [-0.1 to 1.5]; P = 0.100). Secondary outcome analysis did not uncover any additional benefits to liposomal bupivacaine in pain severity at individual timepoints up to 72 h, analgesic consumption, time to first analgesic request, opioid-related side effects, patient satisfaction, length of hospital stay, and functional recovery. No liposomal bupivacaine side effects were reported.

CONCLUSIONS

Perineural liposomal bupivacaine provided a statistically significant but clinically unimportant improvement in the AUC of postoperative pain scores compared with plain local anesthetic. Furthermore, this benefit was rendered nonsignificant after excluding an industry-sponsored trial, and liposomal bupivacaine was found to be not different from plain local anesthetics for postoperative pain and all other analgesic and functional outcomes. High-quality evidence does not support the use of perineural liposomal bupivacaine over nonliposomal bupivacaine for peripheral nerve blocks.

EDITOR’S PERSPECTIVE

Clinical Effectiveness of Liposomal Bupivacaine Administered by Infiltration or Peripheral Nerve Block to Treat Postoperative Pain

The authors provide a comprehensive summary of all randomized, controlled trials (n = 76) involving the clinical administration of liposomal bupivacaine (Exparel; Pacira Pharmaceuticals, USA) to control postoperative pain that are currently published. When infiltrated surgically and compared with unencapsulated bupivacaine or ropivacaine, only 11% of trials (4 of 36) reported a clinically relevant and statistically significant improvement in the primary outcome favoring liposomal bupivacaine. Ninety-two percent of trials (11 of 12) suggested a peripheral nerve block with unencapsulated bupivacaine provides superior analgesia to infiltrated liposomal bupivacaine. Results were mixed for the 16 trials comparing liposomal and unencapsulated bupivacaine, both within peripheral nerve blocks. Overall, of the trials deemed at high risk for bias, 84% (16 of 19) reported statistically significant differences for their primary outcome measure(s) compared with only 14% (4 of 28) of those with a low risk of bias. The preponderance of evidence fails to support the routine use of liposomal bupivacaine over standard local anesthetics.

Effect of Liposomal Bupivacaine on Postoperative Opioid Requirements for Total Hip Arthroplasty, Total Knee Arthroplasty, Laminectomy, Hysterectomy, and Abdominoplasty Procedures

Purpose: Opioid use postoperatively has been linked to adverse events and an increase in opioid dependency. This retrospective study evaluated the effect of using liposomal bupivacaine (LB) for postoperative pain control on total opioid consumption, pain control, serious opioid-related adverse events (ORAEs), and hospital length of stay (LOS) in total knee arthroplasty (TKA), total hip arthroplasty (THA), laminectomy, hysterectomy, and abdominoplasty procedures when compared with a control group. Methods: Patients receiving LB from August 1, 2017, to February 1, 2018, for the aforementioned procedures were included for evaluation, and patients undergoing similar procedures who did not receive LB served as the control group. The principal outcome was opioid consumption through postoperative day 5 or discharge, whichever came first, assessed by morphine milligram equivalents (MMEs). Secondary outcomes included pain scores within 72 hours postoperation, hospital LOS, and serious ORAEs. Results: A total of 323 patients were identified for inclusion in the study: TKA, n = 144; THA, n = 48; laminectomy, n = 73; hysterectomy, n = 30; and abdominoplasty, n = 28. Liposomal bupivacaine use was associated with reduced postoperative opioid consumption compared with alternative therapies with a median 71 MME (25%-75%; interquartile range [IQR] = 32.5-148.5) versus 102 MME (25%-75%; IQR = 57-165), P < .005. However, higher numeric pain scores were reported in the LB group compared with the control group for postoperative day 0 with a median of 5.5 (25%-75%; IQR = 4.5-7.4) versus 5.5 (25%-75%; IQR = 4-7) in the control group ( P < .001) and on postoperative day 1 with a median of 6 (25%-75%; IQR = 4.5-7) versus 5.5 (25%-75%; IQR = 4.3-7), P < .001. There was no difference in hospital LOS or ORAEs. Conclusion: In this retrospective analysis of pain management after TKA, THA, laminectomy, hysterectomy, and abdominoplasty procedures, patients receiving LB consumed significantly less opioid medications. However, this was not associated with clinically meaningful improvements in pain scores, hospital LOS, or serious ORAEs.

Impact of liposomal bupivacaine and provider choice on opioid use and service outcomes in Medicare outpatient surgical patients

AIMS

There is wide variation in opioid prescribing patterns after common surgical procedures. This study examines outcomes for beneficiaries undergoing hospital outpatient department (HOPD) procedures using liposomal bupivacaine (LB) for control of post-surgical pain. As a non-opioid surgical analgesic, LB may afford beneficial outcomes for reducing subsequent opioid use and improving post-surgical service use outcomes.

METHODS

This retrospective cohort comparison study analyzed 100% Medicare claims data from 2014-2019. HOPD claims were matched to approximately 100 of the most common surgical procedures where LB was utilized. Within these procedures, a one-to-many, with replacement propensity score matching model was used to control for possible selection bias. By procedure, those claims which were identified as using LB for control of post-surgical pain were matched to those not receiving LB. Outcomes were the probability of a subsequent Part D opioid prescription fill, emergency department (ED) visit, and short-term acute care hospital admission.

RESULTS

Higher provider use rates of LB are significantly correlated with a decrease in post-HOPD opioid use and a reduction in post-operative ED visits. For each 10% increase in LB use rate by a given provider, Part D opioid events by Day 30 decreased by 2.6 percentage points and by 2.1 percentage points by day 90 (p < .01). Similarly, for each 10% increase in provider LB use rate, there is a 0.4 percentage point reduction in post-operative ED use by day 30 (p < .01) and a 0.3 percentage point reduction by day 90 (p < .05).

LIMITATIONS

Part D data only indicate that a prescription was filled, not whether the drug was taken.

CONCLUSIONS

Increased provider use of LB is correlated with improved patient outcomes in real-world provider experience with the Medicare population for many outpatient procedures. Policies that support increased provider use of LB should reduce reliance on opioid drugs for post-surgical pain management.

Higher incidence of manipulation under anesthesia following TKA associated with the periarticular infiltration of a liposomal bupivacaine cocktail compared to a modified Ranawat cocktail

BACKGROUND

The purpose of this study was to compare the frequency of postoperative stiffness requiring manipulation under anesthesia (MUA) before and after switching from the intraoperative use of liposomal bupivacaine (LB).

METHODS

This was an institutional review board (IRB)-exempt retrospective cohort study (IRB#71733) on all patients who underwent primary total knee arthroplasty (TKA) by a single surgeon between April 2016 and December 2017. We compared 169 knees that received LB group to 167 knees that received a modified Ranawat cocktail (MR group). Perioperative care pathways remained consistent during the study period, as were requirements for MUA which included flexion range of motion below approximately 90 at 6-12 weeks. To compare the incidence of MUA between the groups, a population-averaged Poisson regression analysis was used.

RESULTS

The two groups were similar, with mean age of 63 (range 31-91) in the LB group and 64 (range 42-84) in the MR group, a preponderance of females in both groups (p = 0.866), similar preoperative knee flexion between groups (p = 0.162), and similar Patient-Reported Outcomes Measurement Information System scores. The frequency of MUA, however, was significantly lower in the MR group (LB: 7.7% [95% CI 3.7-12%] vs. MR: 2.4% [95% CI <1-4.7%] [IRR 3.2, 95% CI 1.08-9.76, p . 0.037]).

CONCLUSIONS

In summary, this is a novel report of a potentially previously unrecognized increased incidence of MUA associated with the use of LB compared with a MR cocktail. Given no other notable changes to the perioperative care or MUA thresholds following TKA, the reasons for these findings are unclear but deserve additional investigation.