Single-dose local anesthetics exhibit a type-, dose-, and time-dependent chondrotoxic effect on chondrocytes and cartilage: a systematic review of the current literature

Diffusion doping of analgesics into UHMWPE for prophylactic pain management

Pain management after total joint arthroplasty is often addressed by systemic delivery of opioids. Local delivery of non-opioid analgesic drugs directly in the joint space from the UHMWPE component of the prosthesis would be highly beneficial to increase the efficacy of the drugs, decreasing the overall side effects and the risk of opioid addiction. It has been shown that effective concentrations of local analgesics can be achieved by eluting from analgesic-blended UHMWPE; however, this approach is limited by the decrease in mechanical properties resulting from the extent of phase separation of the blended drugs from the polymeric matrix. Here we hypothesized that mechanical properties could be maintained by incorporating analgesics into solid form UHMWPE by diffusion as an alternative method. Lidocaine or bupivacaine were diffused in solid form UHMWPE with or without radiation crosslinking. The loaded drug content, the spatial distribution of the drugs and their chemical stability after doping were characterized by FTIR and NMR spectroscopy, respectively. Drug release kinetics, tensile mechanical properties and wear rates were assessed. The results showed that diffusion doping could be used as a promising method to obtain a therapeutic implant material without compromising its mechanical and structural integrity.

Review of intra-articular local anaesthetic administration in horses: Clinical indications, cytotoxicity, and outcomes

Equine practitioners frequently inject local anaesthetics (LA) intra-articularly in both diagnosis of lameness and for pain management intra- or post-operatively with synovial endoscopy. Recent reviews of the human and veterinary literature support the concept that chondrotoxicity of LA on joint tissues depends on the type of drug, dose administered, and duration of exposure. The purpose of this review is to summarise the current literature describing intra-articular local anaesthetic use, including both in vitro and in vivo studies, and to draw some comparisons to literature from other species where potential toxicity and duration of effect have been evaluated with the goal of advancing the field's understanding of intra-articular local anaesthetic use in horses, and indicating future directions for the field. The aggregate data available from all species, while generally sparse for horses, indicate that LA are rapidly cleared from the synovial fluid after injection, often within 30 min. In vitro data strongly suggest that lidocaine and bupivacaine are likely more chondrotoxic than other LA, although to what extent is still unknown, and cytotoxicity of LA may be mitigated through concurrent injection with HA, PRP, and drug combinations including nonsteroidal anti-inflammatories and opioids. The current body of in vitro research is not reflective of the in vivo environment, and further in vitro work, if performed, should focus on mimicking the native joint environment, utilising PK data and joint/injection volumes to replicate the native environment more accurately within the joint and the expected exposures to LA.

Cytotoxicity of local anaesthetics and protective effects of platelet rich plasma on equine tenocytes: An in vitro study

Local anaesthetics (LAs) can have detrimental effects on rat, bovine, canine, and human tendon tissues and cells. Currently, there has been no available data on the impact of these drugs on equine tenocytes. Even if LA injection for managing painful tendon conditions in horses is limited, it is usually used via intra-articular, intrasynovial, perineural, and intrathecal as well as for lameness examinations. In this in vitro study, the cytotoxic effects of LAs, including lidocaine, mepivacaine, and bupivacaine on equine tenocytes, in the presence and absence of platelet rich plasma (PRP), were investigated. PRP accelerates tissue healing and can exert cytoprotective effects on different cell types exposed to different stressful conditions, including drugs. Results indicated that the exposure to LAs significantly reduced tenocytes viability in dose- and time-dependent manners while PRP was able to counteract their cytotoxic effects. Furthermore, microscopy and flow cytometry analyses revealed apoptosis and necrosis in equine tenocytes exposed to these drugs, that were both reduced when PRP was in the medium. These findings highlight the importance of considering the tenocyte toxicity associated with intrathecal and intraneural LA injections, as they might affect tenocytes or reduce the efficacy of associated therapies. Moreover, this study also highlights the protective effects of PRP, which could make LA injections safer.

Impact of gadolinium-based MRI contrast agent and local anesthetics co-administration on chondrogenic gadolinium uptake and cytotoxicity

The gadolinium-based contrast agent DOTA-Gd is clinically used in combination with local anesthetics for direct magnetic resonance arthrography. It remains unclear whether gadolinium uptake into cartilage is influenced by co-administration of bupivacaine or ropivacaine and whether DOTA-Gd alters their chondrotoxicity. Gadolinium quantification of chondrogenic spheroids revealed enhanced gadolinium uptake after simultaneous exposure to local anesthetics. Analyses of the spatial gadolinium distribution using synchrotron X-ray-fluorescence scanning indicates gadolinium exposed chondrocytes. In vitro exposure to DOTA-Gd does not alter viability and proliferation of human chondrocytes and the chondrotoxic potential of the anesthetics. Reduced viability induced by ropivacaine was found to be reversible, while exposure to bupivacaine leads to irreversible cell death. Our data suggest that ropivacaine is more tolerable than bupivacaine and that DOTA-Gd exposure does not alter the cytotoxicity of both anesthetics. Enhanced gadolinium uptake into cartilage due to co-administration of anesthetics should find attention.

Notoginsenoside R1 attenuates bupivacaine induced neurotoxicity by activating Jak1/Stat3/Mcl1 pathway

Bupivacaine, a common amide local anesthetic, can provide effective analgesia or pain relief but can also cause neurotoxicity, which remains a mounting concern in clinic and animal care. However, the precise underlying mechanisms have not been fully elucidated. A natural compound, notoginsenoside R1 (NG-R1) has been reported to exhibit a neuroprotective role in stress conditions. In this study, we explored the function and mechanism of NG-R1 in alleviating bupivacaine-induced neurotoxicity in mouse hippocampal neuronal (HT-22) and mouse neuroblastoma (Neuro-2a) cell lines. Our results exhibited that NG-R1 treatment can significantly rescue the decline of cell survival induced by bupivacaine. Tunel staining and western blotting showed that NG-R1 could attenuate BPV‑induced cell apoptosis. Besides, we focused on Mcl1 as a potential target as it showed opposite expression tendency in response to NG-R1 and bupivacaine exposure. Mcl1 knockdown blocked the inhibitory effect of NG-R1 on cell apoptosis against bupivacaine treatment. Intriguingly, we found that NG-R1 can upregulate Mcl1 transcription by activating Stat3 and promote its nuclear translocation. In addition, NG-R1 can also promote Jak1 phosphorylation and docking analysis provide a predicted model for interaction between NG-R1 and phosphorylated Jak1. Taken together, our results demonstrated that NG-R1 can attenuate bupivacaine induced neurotoxicity by activating Jak1/Stat3/Mcl1 pathway.

Pericapsular Nerve Group Block Leads to Small but Consistent Reductions in Pain Between 18 and 24 Hours Postoperatively in Hip Arthroscopy for Femoroacetabular Impingement Surgery: A Prospective, Randomized Controlled Clinical Trial

PURPOSE

To investigate whether the use of a pericapsular nerve group (PENG) block would reduce perioperative pain after arthroscopic therapy for femoroacetabular impingement syndrome (FAIS) and to examine opioid requirements and occurrence of postoperative nausea and vomiting (PONV).

METHODS

Between May 2022 and October 2022, patients (N = 68) undergoing arthroscopic surgery for FAIS were randomly allocated into 2 groups. The first group received an ultrasound-guided PENG preoperatively with 20 mL of 0.375% ropivacaine and standardized postoperative oral medication. The second group received a sham block preoperatively with 20 mL of 0.9% saline and standardized postoperative oral medication. The primary end point was pain scores (visual analog score [VAS], 0-10) during the first 24 hours postoperatively. To quantify clinical significance of outcome achievement for the VAS pain score, the minimal clinically important difference (MCID) was calculated using the half standard deviation method. The incidence of PONV as well as opioid usage (converted to morphine equivalent) within the first 24 hours were secondary outcomes.

RESULTS

Randomization and permission were successfully obtained from 68 participants. From the fifteenth postoperative hour, the PENG group reported significantly less postoperative pain than the control group (24th postoperative hour: VAS pain PENG group 1.3 ± 0.9 [0-3]; 95% confidence interval {CI} 0.4-1.2 vs the VAS pain control group 2.4 ± 1.6 [0-5]; 95% CI 1.4-4.7; P = .009). The VAS pain score threshold for achieving the MCID at 24 hours postoperative was defined as a decrease of 1.1. 27 patients (79%) in the PENG group and 22 patients (65%) in the control group were able to achieve MCID (P = .009). Opioid dosage and postoperative nausea did not differ significantly between groups (P = .987 and P = .655, respectively). Concomitant complications such as falls, hematomas, or weakened muscles did not occur in either group.

CONCLUSIONS

According to this study, a PENG block minimally reduced pain after arthroscopic treatment for FAIS between the 18th and 24th postoperative hours. The PENG group achieved significantly more often the pain VAS MCID. However, there was no proof that the PENG group consumed fewer opioids than the control group. Overall, PONV was found at a low and comparable rate.

LEVEL OF EVIDENCE

Level I, randomized controlled trial.

United Kingdom physiotherapists injection therapy practice for musculoskeletal complaints: A cross-sectional survey

BACKGROUND

Physiotherapists in the United Kingdom (UK), who have received additional training can adopt injection therapy for the treatment of musculoskeletal (MSK) disorders.

OBJECTIVES

The objective of this practice survey was to explore (i) the frequency of use of injection therapy by UK physiotherapists for MSK disorders; and (ii) the clinical reasoning for selection of injectate, dose and pre/post injection practice.

DESIGN

Cross-sectional online survey.

METHODS

The online survey was disseminated via social media and professional networks over a 3-month period. Responses to closed multiple choice survey questions were analysed with descriptive data, with reporting of confidence intervals at 95%. Open questions were analysed using content analysis.

RESULTS

The survey received 320 responses. The majority (86.6%, n = 277) used landmark guided approaches. The highest frequency of injections administered were for trigger digits, sub acromial pain and the knee joint. Corticosteroid drugs were widely used (99.7%, n = 319, CI 95% 98 to 100) with Triamcinolone (Kenalog) being the most frequently utilised for both joints (58.8%, n = 160, 53 to 65) and soft tissues (46.3%, n = 126, 40 to 52). Drug choice was largely based on availability in clinic (47.1%, n = 128, 41 to 53). Drug doses for common injection sites varied among the respondents with variation also evident in pre and post-injection practice.

CONCLUSION

Marked variation across some elements of injection therapy practice was evident. Notable differences in corticosteroid preparation used, the doses of drug injected, and the use of local anaesthetic were reported by respondents. Injecting physiotherapists should endeavour to ensure practice is aligned to best available evidence.

FactFinders for patient safety: Preventing local anesthetic-related complications: Local anesthetic chondrotoxicity and stellate ganglion blocks

This series of FactFinders presents a brief summary of the evidence and outlines recommendations to improve our understanding and management of several potential local anesthetic-related complications. Evidence in support of the following facts is presented. (1) Chondrotoxicity: Which Local Anesthetics are Safest for Intraarticular Injection? -- There are drug-, concentration-, and time-dependent chondrotoxic effects that vary between local anesthetics. Current evidence related to commonly used local anesthetics indicates that with exposure to equivalent volumes, bupivacaine, at concentrations of 0.5 % or higher, is the most chondrotoxic agent, while ropivacaine, at concentrations equal to or less than 0.5 %, is the least chondrotoxic in vitro. There is minimal published evidence that confirms these findings in vivo. (2) Minimizing Risks with Stellate Ganglion Blocks -- Evidence suggests that fluoroscopic or ultrasound guidance reduces the risk and increases the accuracy of SGB. Utilizing ultrasound guidance has the added benefit of soft tissue visualization, especially vascular structures, which has the potential to prevent adverse outcomes when compared to the fluoroscopic technique.

Does response to preoperative intra-articular anesthetic injections predict outcomes of femoroacetabular impingement syndrome?

INTRODUCTION

Some patients with femoroacetabular impingement syndrome (FAIS) who undergo surgery do not show satisfactory outcomes. Reliable tests that can inform prognosis of FAIS surgery are needed for optimized indications and contraindications to surgery. We aimed to review and critically appraise available literature on the capability of patient response to preoperative intra-articular anesthetic injections (PIAI) to predict post-surgical outcomes in patients with FAIS.

MATERIALS AND METHODS

This study was conducted in accordance with the PRISMA statement. Studies that assessed the patient pain response to PIAI and post-surgical outcomes in patients with FAIS were considered eligible. Study selection and data collection were performed by three independent reviewers. Main outcomes evaluated were those measured by hip outcome scales often used in assessing postoperative pain and functional recovery, such as the modified Harris Hip Score (mHHS) and international Hip Outcome Tool (iHOT). The likelihood ratio of achieving satisfactory postoperative outcomes at the mHHS (LHR) was extracted or calculated-for patients with significant response to PIAI and for those without a significant response to PIAI. The risk of bias was assessed using the Quality In Prognosis Studies (QUIPS) tool.

RESULTS

Six studies were considered eligible for analysis. Five studies indicated that patient response to PIAI are associated to surgical outcomes for patients with FAIS, with a greater reduction in pain typically indicating a better surgical outcome. Additionally, the LHR ranged from 1.15 to 1.92 for patients with significant response to PIAI (I2 = 90.6%). For patients without a significant response, the LHR ranged from 0.18 to 0.65 (I2 = 87.5). An overall high risk of bias was observed for all studies included in the analysis. Study attrition, the prognostic factor measurement and the presence of confounding factors were the main sources of bias.

CONCLUSIONS

Greater reductions in pain with preoperative intra-articular anesthetic injections were found to be associated to better outcomes after FAIS surgery, but all available studies contain a high risk of bias.

Intraarticular Injections in the Foot and Ankle: Medication Selection Patterns and Perceived Risk Of Chondrotoxicity

Background

Intraarticular corticosteroid injections (ICIs) are widely used to treat foot and ankle conditions. Although laboratory studies indicate certain corticosteroids and local anesthetics used in ICIs are associated with chondrotoxic effects, and selected agents such as ropivacaine and triamcinolone may have less of these features, clinical evidence is lacking. We aimed to identify the patterns of drug selection, perceptions of injectate chondrotoxicity, and rationale for medication choice among surgeons in the American Orthopaedic Foot & Ankle Society (AOFAS).

Methods

An e-survey including demographics, practice patterns, and rationale was disseminated to 2011 AOFAS members. Frequencies and percentages were calculated for demographic data, anesthetic and steroid choice, rationale for injectate choice, and perception of chondrotoxicity. Bivariate analysis was used to identify practice patterns significantly associated with perceptions of injectate risk and rationale.

Results

In total, 387 surveys were completed. Lidocaine and triamcinolone were the most common anesthetic and corticosteroid used (51.2% and 39.3%, respectively). Less than half of respondents felt corticosteroids or local anesthetics bear risk of chondrotoxicity. Respondents agreeing that corticosteroids are chondrotoxic were more likely to use triamcinolone (P = .037). Respondents agreeing local anesthetics risk chondrotoxicity were less likely to use lidocaine (P = .023). Respondents choosing a local anesthetic based on literature were more likely to use ropivacaine (P < .001).

Conclusion

Corticosteroid and local anesthetic use in ICIs varied greatly. Rationale for ICI formulation was also variable, as the clinical implications are largely unknown. Those who recognized potential chondrotoxicity and who chose based on literature were more likely to choose ropivacaine and triamcinolone, as reflected in the basic science literature. Further clinical studies are needed to establish guidelines that shape foot and ankle ICI practices based on scientific evidence and reduce the variation identified by this study.

Level of Evidence

Level IV, cross-sectional survey study.

Tips and tricks in ultrasound-guided musculoskeletal interventional procedures

Ultrasound visualization affords proceduralists versatile and accurate guidance for a variety of percutaneous, minimally invasive procedures in the musculoskeletal system including joint (intra-articular) injections or aspirations, intra-bursal injections, peritendinous, and perineural injections. A variety of percutaneous procedures are traditionally performed blindly, but may be more easily or more accurately performed with the real-time assistance of ultrasound guidance. Other procedures are only possible utilizing image-guidance, due to the required precision of the injection because of delicate local anatomy or depth of the injection; ultrasound is a safe, portable, and widespread modality that can be used to assist the proceduralist in localizing the needle tip in such cases, to ensure safe and accurate delivery of the medication, most frequently a solution of steroid and anesthetic. This review aims to provide a foundational approach to ultrasound-guided procedures in the musculoskeletal system, offering tips and tricks that can be employed in many different procedures including intra-articular, juxta-articular, and perineural injections for a multitude of clinical scenarios. Technical considerations regarding ultrasound transducer selection, sonographic technique, as well as common indications, contraindications, and complications of these procedures, are presented. Additionally, a variety of pharmacologic considerations for proceduralists contemplating ultrasound-guided injections are discussed.

Intra-articular corticosteroids associated with increased risk of total hip arthroplasty at 5 years

BACKGROUND

Intra-articular corticosteroid injections are commonly administered for hip pain. However, guidelines are conflicting on their efficacy, particularly in patients without arthritis. This study assessed for an association of corticosteroid injections and the incidence of total hip arthroplasty at 5 years.

METHODS

Patients with a diagnosis of hip pain without femoroacetabular osteoarthritis who were administered an intra-articular corticosteroid injection of the hip within a 2-year period were identified from the Mariner PearlDiver database. Patient were matched to patients with a diagnosis of hip pain who did not receive an injection. 5-year incidence of total hip arthroplasty was compared between matched patients who received an intra-articular corticosteroid injection and those who did not.

RESULTS

2,540,154 patients diagnosed with hip pain without femoroacetabular arthritis were identified. 25,073 (0.9%) patients received a corticosteroid injection and were matched to an equal number of control patients. The incidence of total hip arthroplasty (THA) at 5-year-follow up was significantly higher for the corticosteroid cohort compared to controls (1.1% vs. 0.5%; p < 0.001). The incidence and risk of THA increased along with number of injections (1 injection: 0.8%, OR 1.37; 95% CI, 1.34-1.42; p < 0.001, 2 injections: 1.1%; OR 1.45; CI, 1.40-1.50; p < 0.001, ⩾3 injections: 1.5%; OR 1.48; CI, 1.40-1.56; p < 0.001).

CONCLUSIONS

There may be a dose-dependent association of corticosteroid injections and a greater risk of total hip arthroplasty at 5 years. These results along with the conflicting guidelines on the efficacy of intra-articular steroids for hip pain should prompt physicians to consider osteoarthritis progression that may occur in the setting of corticosteroid injections in non-arthritic hips.

Comparison of Analgesia Treatment Methods After Arthroscopic Rotator Cuff Repair: A Network Meta-analysis of 42 Randomized Controlled Trials

Background

The optimal method for postoperative analgesia after arthroscopic rotator cuff repair (ARCR) is still unclear.

Purpose

To compare the efficacy of postoperative analgesic methods after ARCR through network meta-analysis of randomized controlled trials and prospective controlled trials.

Study Design

Systematic review; Level of evidence, 2.

Methods

Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we searched PubMed, Embase, and Web of Science from inception until April 12, 2022, for randomized controlled trials and prospective controlled trials evaluating neuraxial analgesia, peripheral nerve block, periarticular local anesthetic infiltration, intravenous patient-controlled analgesia, oral analgesia, or any combination of these methods for pain management after ARCR. Outcomes included pain scores at rest, morphine consumption, and complications (nausea and vomiting). Study quality was assessed using the Cochrane risk-of-bias tool. Network meta-analysis was used to assess the relative efficacy of the methods for postoperative analgesia. The best choice for postoperative analgesia was defined as the one with significant differences in pain scores and morphine consumption compared with placebo, with no significant difference in complications, during the initial 48 hours postoperatively.

Results

Included were 42 studies with 3110 patients. Only suprascapular nerve block (SSNB) was significantly superior to placebo in pain scores (mean difference [MD], -0.93 [95% CI, -1.31 to -0.54] at 6 hours; MD, -2.34 [95% CI, -3.49 to -1.19] at 12 hours) and morphine consumption (MD, -17.70 [95% CI, -32.98 to -2.42] at 24 hours) (P < .05 for all), with no difference in complications (odds ratio, 0.96 [95% CI, 0.21 to 4.32]; P > .05). Pain scores were significantly lower with interscalene nerve block compared with SSNB (MD, -0.69 [95% CI, -1.17 to -0.20] at 6 hours; MD, -1.44 [95% CI, -2.21 to -0.67] at 12 hours) and with SSNB + axillary nerve block compared with SSNB (MD, -3.09 [95% CI, -4.18 to -1.99] at 6 hours; MD, -0.87 [95% CI, -1.71 to -0.03] at 12 hours) (P < .05 for all).

Conclusion

Based on the current evidence, most analgesic methods lowered pain and morphine consumption compared with placebo. There were significant differences in pain scores between interscalene nerve block and SSNB during the first 12 hours postoperatively, and adding axillary nerve block to SSNB enhanced the analgesic effect.

In vitro chondrotoxicity of bupivacaine, levobupivacaine and ropivacaine and their effects on caspase activity in cultured canine articular chondrocytes

Bupivacaine, levobupivacaine and ropivacaine are potent, long acting, amide-type local anesthetics that have several clinical applications including intra-articular administration. The objectives of this study were to evaluate their in vitro effects on cell viability and caspase activity to elucidate whether they activate the extrinsic or intrinsic pathways of apoptosis in canine articular chondrocytes. Chondrocytes in monolayer culture were treated with culture medium as the control, or with 0.062% (0.62 mg/mL) bupivacaine, 0.062% levobupivacaine, and 0.062% ropivacaine for 24 hr. Cell viability was evaluated using the live/dead, 3-(4,5-dimehylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT), and Cell Counting Kit-8 (CCK-8) assays. Evaluation of caspase-3, caspase-8, and caspase-9 activity was performed using colorimetric assays. The MTT and CCK-8 assays were used to evaluate the effect of caspase inhibitors on local anesthetic chondrotoxicity. All three local anesthetics decreased chondrocyte viability after 24 hr (P<0.001). Apoptosis was induced through both the extrinsic and intrinsic pathways. Bupivacaine increased caspase-3, caspase-8, and caspase-9 activity (P<0.001). Levobupivacaine increased caspase-3 (P=0.03) while ropivacaine did not significantly upregulate activity for all three caspases. Caspase inhibition did not suppress bupivacaine chondrotoxicity whereas inhibition of caspase-8 and caspase-9 decreased ropivacaine chondrotoxicity and mildly attenuated levobupivacaine chondrotoxicity. In summary, the level of chondrotoxicity, the type of caspase activated, the level of caspase activation, and the response to caspase inhibitors was dependent on the type of local anesthetic. Therefore, ropivacaine may be a safer choice for intra-articular administration compared to levobupivacaine and bupivacaine.

Concurrent versus delayed exposure to corticosteroids in equine articular tissues cultured with local anesthetic

OBJECTIVE

To determine the effect of concurrent versus delayed treatment with corticosteroid on equine articular tissues also treated with local anesthetic in vitro in the presence of inflammatory mediators.

STUDY DESIGN

Controlled laboratory study.

ANIMALS

Five geldings, one mare (aged 3-18 years).

METHODS

From each horse, 24 synovial and 12 osteochondral explants were cultured in a 12-well plate (2 wells/group, 2 synovial and 1 osteochondral explant/well, total 216 explants in the study). Explants were stimulated in culture medium with 10 μg/ml recombinant equine interleukin-1β and 10 μg/ml tumor necrosis factor-α for 48 hours, then randomly assigned to six treatments: unstimulated control, stimulated control, triamcinolone acetonide (TA, 10^-6  M), mepivacaine hydrochloride (MH, 4.4 mg/ml), MH + TA (concurrent) and MH + TA (delayed). The delayed group was treated with MH and, 6 days later, treated with TA. Every 3 days for 9 days total, medium levels of lactate dehydrogenase (LDH), prostaglandin E₂ (PGE₂ ), matrix metalloproteinase 13 (MMP-13) and glycosaminoglycan (GAG) were quantified via ELISA. Data were analyzed with mixed-effects models with Tukey's multiple comparisons.

RESULTS

Stimulation increased medium PGE₂ and MMP-13 and had no effect on LDH or GAG. Treatment with MH increased LDH and decreased PGE₂ and MMP-13. Treatment with TA decreased PGE₂ and MMP-13.

CONCLUSION

There were no differences in cytotoxicity, inflammation or matrix degradation for delayed or concurrent MH and TA treatment groups up to 9 days in culture.

CLINICAL SIGNIFICANCE

The lack of an effect of concurrent versus delayed treatment might indicate that concurrent therapy is acceptable.

The long head of biceps at the shoulder: a scoping review

BACKGROUND

This review aimed to explore the available literature to update our understanding of the long head of biceps (LHB) at the shoulder. Synthesise our findings to identify emergent themes and knowledge gaps to inform future research and management directions.

METHODS

PubMed, Embase, Cinahl, SportDiscus, CENTRAL, and Web of Science were searched from inception to 31st December 2021. Articles were included if they referenced adult participants > 18 years of age and were written in English.

RESULTS

214 articles were included in the final analysis, and results were categorised into six emergent themes: (1) Anatomy - Normal anatomical variation of the biceps from aberrant origins, third and fourth accessory heads, and an absence of the LHB tendon (LHBT) are not necessarily benign, with shoulder pain and instability a commonly reported theme. (2) Function - Bicep's role in glenohumeral elevation and stability in healthy shoulders is minimal. In contrast, LHB has a more significant role in shoulder stability and humeral head depression in subjects with rotator cuff failure or an absent LHBT. (3) Pathology - There is an association between LHB tendinopathy, rotator cuff disease, LHBT instability and occult rotator cuff tears. Early recruitment and hyperactivity of the LHB in subjects with symptomatic rotator cuff tears and instability suggest a potential compensatory role. (4) Assessment - The limited diagnostic utility of special orthopaedic tests in assessing LHBT pathology was a consistent theme. The utility of magnetic resonance imaging and ultrasound to identify full-thickness tendon tears and instability of the LHBT was moderate to high. However, the utility of clinical tests and imaging may be underestimated due to arthroscopy's limitations in fully visualising the proximal LHBT. (5) Non-Surgical Management - Ultrasound-guided injections into the biceps sheath show greater accuracy and patient outcomes than blinded injections; however, the entry of injectate into the intraarticular glenohumeral joint may have unwanted complications. (6) Surgical management - For the surgical management of biceps pathology with or without rotator cuff pathology, both biceps tenodesis and tenotomy report similar improvements in pain without any significant adverse effect on strength or function. Tenodesis favoured higher overall constant scores and a lower incidence of Popeye deformity and cramping arm pain, with tenotomy trending to be more cost and time effective. For patients with a healthy LHBT, rotator cuff repair with adjunctive tenodesis or tenotomy fails to provide additional clinical improvements compared to rotator cuff repair in isolation.

CONCLUSIONS

The scoping review highlights the variability of biceps anatomy, which is not necessarily benign and suggests a minimal role of the LHB in shoulder elevation and stability in healthy individuals. In contrast, individuals with rotator cuff tears experience proximal humeral migration and demonstrate hyperactivity of the LHB, suggesting a potential compensation role. The observed prevalence of LHBT pathology with rotator cuff tears is well established; however, the cause-and-effect relationship between LHBT pathology and rotator cuff disease is undetermined. The diagnostic utility of clinical tests and imaging to exclude LHBT pathology may be understated due to the limitations of arthroscopy to visualise the proximal LHBT fully. Rehabilitation programs for the LHB are understudied. Similar post-surgical clinical outcomes are observed for tenodesis and tenotomy for biceps and rotator cuff-related shoulder pain. Subjects undergoing biceps tenodesis are less likely to have cramping arm pain and a Popeye deformity than patients undergoing biceps tenotomy. The significance of routine surgical removal of the LHBT and sequelae on rotator cuff tear progression to failure and long-term shoulder function is unknown, and further research is required.

PRE-REGISTRATION

OSF: https://osf.io/erh9m.

Efficacy of epinephrine in local infiltration analgesia on pain relief and opioid consumption following total knee arthroplasty: a randomized controlled trial

BACKGROUND AND PURPOSE

Local infiltration analgesia (LIA) is one of the effective regimens to reduce pain after total knee arthroplasty (TKA). Epinephrine is a commonly used sympathetic adjunct in LIA. It is expected to enhance the intensity and extend the duration of LIA. The primary aim of the study was to evaluate the efficacy of epinephrine on postoperative pain control after primary TKA.

PATIENTS AND METHODS

A total of 80 patients who underwent primary TKA were randomized into an epinephrine (EN) and a control (C) group. Postoperative visual analogue pain score (VAPS) and morphine consumption were recorded every 6 hours until 48 hours after operation. The VAPS 6-48 hours were compared using repeated measure statistics. The range of motion (ROM) on discharge and complications were also compared between these 2 groups.

RESULTS

The study showed that although VAPS differed statistically between the 2 groups at 12 hours (C higher) and 48 hours (C lower) postoperatively (p = 0.04 and 0.02, respectively), repeated measures analysis revealed that there were no significant differences in 6-48 hours VAPS (p = 0.6). Total morphine consumption in the EN and C groups was 3.4 (SD 3.7) and 4.2 (SD 4.4) mg, respectively (p = 0.4). ROM on discharge was also similar between the groups. No complications were detected in this study.

CONCLUSION

Our study showed that additional epinephrine in LIA had a statistically significant reduction in VAPS at 12 hours and morphine usage during 6-12 hours when compared with the control group. However, the magnitude of difference did not reach minimal clinically importance difference (MCID) value for TKA.

Can pre-operative intraarticular injection predict pain relief after total hip arthroplasty?

BACKGROUND

To study if pain relief after injection and arthroplasty correlate.

METHODS

A retrospective cohort study included consecutive patients (n = 88; median age 64 (interquartile range (IQR) 22) years, 49 (56%) females) that received fluoroscopic-guided intra-articular hip injection with contrast agent, anaesthetic (diagnostic), and corticosteroid (therapeutic) before implantation of primary total hip arthroplasty. Pain scores were assessed pre-injection, post-injection after 15 min (diagnostic phase) at first clinical follow up (therapeutic phase; median 2 (IQR 2) months), and postoperatively (last follow up (median 15 (IQR 5) months)). Responders had reduction in pain score ≥ 20 (numeric rating scale 0-100) points. The primary outcome was the same (or inverse) response to injection and arthroplasty.

RESULTS

The median pain scores were higher pre-injection (68 (IQR 30) points) compared to the diagnostic phase (18 (IQR 40) points; p < 0.001), therapeutic phase (50 (IQR 40) points; p < 0.001), and post-operatively (2 (IQR 15) points; p < 0.001). On the one hand, 69 (78%) cases had the same response in the diagnostic phase and post-operatively (rho = 0.58; p < 0.001; sensitivity 83%); on the other hand 32 (36%) cases had the same response in the therapeutic phase and post-operatively (rho = 0.25; p < 0.001; sensitivity 33%). Furthermore, 57% and 91% of patients had an even better response post-operatively than in the diagnostic and therapeutic phases.

CONCLUSIONS

Pre-operative intraarticular injection can predict pain relief after primary total hip arthroplasty. A positive response to hip arthroplasty may be better predicted by the response to local anaesthetic (diagnostic phase) than corticosteroids. Most patients (91%) with osteoarthritis may expect better pain relief after arthroplasty compared to the therapeutic phase after injection.

Cytotoxicity of Local Anesthetics on Bone, Joint, and Muscle Tissues: A Narrative Review of the Current Literature

Background

Local anesthetics are commonly used in surgical procedures to control pain in patients. Whilst the cardiotoxicity and neurotoxicity of local anesthetics have received much attention, the cytotoxicity they exert against bone, joint, and muscle tissues has yet to be well recognized.

Objective

This review aimed to raise awareness regarding how local anesthetics may cause tissue damage and provide a deeper understanding of the mechanisms of local anesthetic-induced cytotoxicity. We summarized the latest progress on the cytotoxicity of local anesthetics and the underlying mechanisms and discussed potential strategies to reduce it.

Findings

We found that the toxic effects of local anesthetics on bone, joint, and muscle tissues were time- and concentration-dependent in vitro. Local anesthetics induced apoptosis, necrosis, and autophagy through specific cellular pathways. Altogether, this review indicates that toxicity of local anesthetics may be avoided by rationally selecting the appropriate anesthetic, limiting the total amount, and determining the lowest effective concentration and duration.

Interventional Therapies for Osteoarthritis: An Update

Osteoarthritis (OA) is one of the most common diseases worldwide and is expected to increase in incidence as the age of the general population rises. Both oral medications, such as NSAIDs, and surgical treatments used for OA management have limitations. Demand is rising for minimally invasive techniques such as intraarticular injections and percutaneous interventions for use in place of or in conjunction with oral medications and surgical therapies, and the past 2 decades have seen a rapid expanse in both pharmacologic and nonpharmacologic minimally invasive OA treatments. Image guidance with fluoroscopy, CT, or ultrasound is often used in conjunction with these procedures to achieve precise treatment localization to achieve maximal therapeutic effect. The choice of modality used for image guidance is often influenced by clinician experience, patient characteristics, and equipment availability. This article reviews the mechanisms of action, contraindications, complications, and efficacy of conventional and developing minimally invasive OA treatments. The minimally invasive treatment options described in this Review include therapeutic injections such as antiinflammatory agents, viscosupplements, and biologics, as well as nonpharmacologic treatments of subchondroplasty, nerve ablation, genicular artery embolization, intraarticular pulsed radiofrequency therapy, and MRI-guided focused ultrasound therapy.

Effect of species, concentration and volume of local anesthetics on intervertebral disk degeneration in rats with discoblock

PURPOSE

Discoblock is effective in relieving discogenic low back pain, but it can also cause intervertebral disk degeneration (IDD). The effect of species, concentration and volume of local anesthetics on IDD with discoblock have not been reported. The purpose was to study the effect of species, concentration and volume of local anesthetics on IDD in rats undergoing discoblock.

METHODS

The effects of local anesthetics on nucleus pulposus cell (NPC) viability in vitro were studied. NPCs were exposed to lidocaine, bupivacaine and ropivacaine at different concentrations. NPC viability was measured. The least cytotoxic local anesthetic was used in vivo. The concentration and volume of local anesthetics on IDD in rat with discoblocks were tested in vivo. Detection indicators included X-ray, MRI, water content of the disk and histological changes.

RESULTS

The toxicity of local anesthetics to NPCs was dose and time dependent, and the cytotoxicity of different local anesthetics was different. Among the three local anesthetics, ropivacaine was the least toxic to NPCs. The effect of ropivacaine concentration on IDD was not significant, as detected by X-ray, MRI, disk water content and histology (P < 0.05). The volume of ropivacaine has a significant effect on IDD, as supported by X-ray, MRI, disk water content and histology (P < 0.05). Acupuncture itself significantly increased IDD, as detected by MRI, disk water content and histology (P < 0.05).

CONCLUSION

Ropivacaine should be selected for its low cytotoxicity. A lower volume and slow injection speed should be used to reduce IDD during discoblock.

Pharmacokinetics and local tissue response to local instillation of vocacapsaicin, a novel capsaicin prodrug, in rat and rabbit osteotomy models

Vocacapsaicin is a novel prodrug of trans-capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) being developed as a nonopioid, long-lasting, site-specific treatment for postsurgical pain management. The objective of these studies was to examine the safety and tolerability of vocacapsaicin in an osteotomy model in two animal species and to evaluate bone healing parameters. Rats undergoing unilateral femoral osteotomy received a single perioperative administration (by instillation) of vocacapsaicin (vehicle, 0.15, 0.3, and 0.6 mg/kg). Rabbits undergoing unilateral ulnar osteotomy received a single perioperative administration (by infiltration and instillation) of vocacapsaicin (vehicle, 0.256 and 0.52 mg) alone or in combination with 0.5% ropivacaine. Clinical signs, body weights, food consumption, radiography, histopathologic examinations, ex vivo bone mineral density measurements (rats only), and biomechanical testing were evaluated at 4 and 8 weeks in rats and at 2 and 10 weeks in rabbits. Plasma samples were also collected in rabbits. There were no vocacapsaicin-related effects on mortality, clinical observations, body weight, or food consumption in either species. Systemic exposure to vocacapsaicin and its metabolites, including capsaicin, was transient. In rats, vocacapsaicin was devoid of deleterious effects on bone healing parameters, and there was a trend for enhanced bone healing in rats treated with the mid-dose. In rabbits, vocacapsaicin administered alone or in combination with ropivacaine did not adversely affect bone healing parameters. In conclusion, a single perioperative administration of vocacapsaicin in unilateral osteotomy models was well tolerated, locally and systemically, supporting its continued development as a novel, nonopioid treatment for postsurgical pain management.

Review article: Ankle intra-articular haematoma block for reduction of unstable ankle fractures in the emergency department: An integrative review

A review was conducted to assess the efficacy and safety of the intra-articular haematoma block (IAHB) for manipulation of ankle fractures in ED. Any study investigating the success of IAHB for ankle fracture reduction published in English was sought. Seven databases were searched. The Cochrane Risk of Bias tool was used to quality assess the included studies. Three studies met the inclusion criteria (n = 436 patients). Just one study was a randomised controlled trial (n = 42). The two non-randomised studies that included the majority of patients were assessed as at high overall risk of bias. The studies reported no significant difference in the overall rate of successful reduction or patient-reported pain scores between IAHB and procedural sedation groups. A subgroup analysis in one study suggested timelier reduction by 51.4 min (P = 0.01) for fractures involving subluxation when using IAHB, but that more patients with dislocation were reduced on first attempt when using procedural sedation compared to IAHB (74.0% vs 54.8%, P < 0.01). No adverse events were reported from using IAHB, although no study measured events such as joint sepsis or chondrolysis. Findings suggest that IAHB might be safe and effective but the evidence is very limited. High-quality research is required before IAHB can be considered a routine alternative. However, IAHB could be considered in situations where the risk of procedural sedation outweighs the likely very low risk of chondrolysis.

Management of Patients with Adhesive Capsulitis via Ultrasound-Guided Hydrodilatation without Concomitant Intra-Articular Lidocaine Infusion: A Single-Center Experience

Considering the potential chondrotoxic effects of lidocaine, this retrospective study aimed to examine whether ultrasound-guided hydrodilatation without concurrent lidocaine infusion can still provide comparable treatment benefits for patients with adhesive capsulitis (AC). Outpatient data from 104 eligible AC patients who received ultrasound-guided hydrodilatation between May 2016 and April 2021 were reviewed. A total of 59 patients received hydrodilatation with diluted corticosteroid only, while 45 patients received treatment with mixed, diluted corticosteroid and 1% lidocaine. The overall treatment outcome was documented as the percentage of clinical improvement, ranging from 0% to 100% compared to baseline, and it was ranked into poor, moderate and good treatment outcomes. The results show no significant group-wise difference in demographics, overall treatment outcome, and number of hydrodilatations, while most patients showed moderate and good treatment outcomes. Patients with lidocaine infusion did not show greater treatment benefit. Our results suggest that ultrasound-guided hydrodilatation without concurrent lidocaine infusion can still deliver good treatment benefits for AC patients, and the findings are supportive of a modified approach toward careful intra-articular local anesthetic use during management of AC in the primary care setting.

Shoulder structure and function: The impact of osteoarthritis and rehabilitation strategies

STUDY DESIGN

Invited review.

BACKGROUND

Shoulder osteoarthritis can result in significant functional deficits. To improve diagnosis and treatment, we must better understand the impact of osteoarthritis on shoulder biomechanics and the known mechanical benefits of currently available treatments.

PURPOSE

The purpose of this paper is to present up-to-date data on the effects of osteoarthritis and rehabilitation on the biomechanical parameters contributing to shoulder function. With this goal, we also reviewed the anatomy and the ranges of motion of the shoulder.

METHODS

A search of electronic databases was conducted. All study designs were included to inform this qualitative, narrative literature review.

RESULTS

This review describes the biomechanics of the shoulder, the impact of osteoarthritis on shoulder function, and the treatment of shoulder osteoarthritis with an emphasis on rehabilitation.

CONCLUSIONS

The shoulder is important for the completion of activities of daily living, and osteoarthritis of the shoulder can significantly reduce shoulder motion and arm function. Although shoulder rehabilitation is an integral treatment modality to improve pain and function in shoulder osteoarthritis, few high-quality studies have investigated the effects and benefits of shoulder physical and occupational therapies. To advance the fields of therapy and rehabilitation, future studies investigating the effects of therapy intensity, therapy duration, and the relative benefits of therapy subtypes on shoulder biomechanics and function are necessary.

Most Analgesia Treatments Have No Clinical Significance for Anterior Cruciate Ligament Reconstruction: A Network Meta-analysis of 66 Randomized Controlled Trials

PURPOSE

To assess the relative efficacy of several clinical treatments for postoperative analgesia of anterior cruciate ligament reconstruction through network meta-analysis based on multiple published randomized controlled trials.

METHODS

We searched PubMed, the Cochrane library, EMBASE, and Web of Science, each from inception until February 15, 2021. Outcomes including pain scores at rest (visual analog scale, numerical rating scales, and other scales, which were converted to a standardized 0-10 scale), morphine consumption, and complications were meta-analyzed. Quality of the included studies was assessed using the Cochrane risk-of-bias tool. The authors defined the best choice for postoperative analgesia as the one that had significant difference in pain scores, morphine consumption, and had no significant difference in the risk of complications compared with placebo in the initial 48 postoperative hours.

RESULTS

In total, 66 studies with 4,168 patients were included in this network meta-analysis. Only periarticular infiltration was significantly superior to placebo in pain scores and morphine consumption (pain at 2 hours: mean difference [MD] -0.74, 95% confidence interval [CI] -1.36 to -0.12; pain at 6 hours: MD -0.81, 95% CI -1.42 to -0.21; pain at 12 hours: MD -0.85, 95% CI -1.53 to -0.17; pain at 24 hours: MD -0.80, 95% CI -1.19 to -0.40; morphine consumption at 24 hours: MD -10.12, 95% CI -14.31 to -5.93; morphine consumption at 48 hours: MD -5.62, 95% CI -6.74 to -4.51). Periarticular infiltration did not increase the risk of complications compared with placebo (nausea and vomiting: odds ratio [OR] 0.63, 95% CI 0.34-1.16; pruritus: OR 0.74, 95% CI 0.35-1.58; urinary retention: OR 0.55, 95% CI 0.25-1.23). In addition, There was no significant difference between adductor canal block and femoral nerve block in pain scores and morphine consumption (pain at 2 hours: MD -0.01, 95% CI -1.44 to 1.42; pain at 6 hours: MD 0.29, 95% CI -0.28 to 0.86; pain at 12 hours: MD 0.36, 95% CI -0.44 to 1.16; pain at 24 hours: MD 0.26, 95% CI -0.22 to 0.75; pain at 48 hours: MD -0.36, 95% CI -0.97 to 0.24; morphine at 24 hours: MD 1.04, 95% CI -4.70 to 6.79; morphine at 48 hours: MD -0.32, 95% CI -0.70 to 0.07; postoperative nausea and vomiting: OR 1.07, 95% CI 0.55-2.09; pruritus: OR 1.36, 95% CI 0.66-2.79; urinary retention: OR 1.41, 95% CI 0.37-5.29).

CONCLUSIONS

Based on current evidence, most analgesic methods could result in lower pain scores and decrease morphine consumption when compared with placebo; however, differences between methods were small and inconsistent. There seemed to be no significant difference between adductor canal block and femoral nerve block in pain score, morphine consumption and complications.

LEVEL OF EVIDENCE

Level I, meta-analysis of Level I RCTs.

Dexamethasone Does not Compensate for Local Anesthetic Cytotoxic Effects on Tenocytes: Morphine or Morphine Plus Dexamethasone May Be a Safe Alternative

Purpose

The purposes of this in vitro study were to investigate whether the addition of dexamethasone can compensate for any cytotoxic effects of the amide-type local anesthetics (LA) bupivacaine and ropivacaine and whether morphine and morphine-6-glucuronide (M6G) may be a safe alternative for peritendinous application.

Methods

Biopsies of human biceps tendons (n = 6) were dissected and cultivated. Cells were characterized by the expression for tenocyte markers, collagen I, biglycan, tenascin C, scleraxis, and RUNX via reverse transcriptase-polymerase chain reaction and immunohistochemistry. Tenocytes were incubated with bupivacaine, ropivacaine, morphine, M6G, or a saline control with and without addition of dexamethasone for 15, 60, or 240 min. Cell viability was determined by quantifying the presence of adenosine-triphosphate.

Results

Significant time-dependent cytotoxic effects were observed for LA after all exposure times. After 15, 60, and 240 minutes, cell viability decreased to 81.1%, 49.4% and 0% (P < .001) for bupivacaine and to 81.4%, 69.6%, and 9.3% (P < .001) for ropivacaine compared to saline control. Dexamethasone did not compensate for these cytotoxic effects. Cell viability was not affected after 15, 60-min exposures to morphine and M6G but decreased significantly (P < .001) after 240 minutes compared to saline control. However, in combination with dexamethasone, tenocyte viability was significantly increased at all times for morphine (P < .01) and at 15 and 60 minutes for M6G (P < .01).

Conclusions

The results showed that amide-type LA have a time-dependent cytotoxic effect on human tenocytes in vitro, which could not be compensated for by dexamethasone, whereas morphine and M6G had no cytotoxic effects on tenocytes after 15 and 60 minutes. The addition of dexamethasone to morphine and M6G had a positive effect on viability, which increased significantly compared to the opioids.

Clinical Relevance

It is known that amide-type local anesthetics used for local joint analgesia have chondrotoxic side-effects. The combined application of morphine and dexamethasone may be a safe alternative.

Comparison of in vitro and in vivo Toxicity of Bupivacaine in Musculoskeletal Applications

The recent societal debate on opioid use in treating postoperative pain has sparked the development of long-acting, opioid-free analgesic alternatives, often using the amino-amide local anesthetic bupivacaine as active pharmaceutical ingredient. A potential application is musculoskeletal surgeries, as these interventions rank amongst the most painful overall. Current literature showed that bupivacaine induced dose-dependent myo-, chondro-, and neurotoxicity, as well as delayed osteogenesis and disturbed wound healing in vitro. These observations did not translate to animal and clinical research, where toxic phenomena were seldom reported. An exception was bupivacaine-induced chondrotoxicity, which can mainly occur during continuous joint infusion. To decrease opioid consumption and provide sustained pain relief following musculoskeletal surgery, new strategies incorporating high concentrations of bupivacaine in drug delivery carriers are currently being developed. Local toxicity of these high concentrations is an area of further research. This review appraises relevant in vitro, animal and clinical studies on musculoskeletal local toxicity of bupivacaine.

Preemptive analgesia in hip arthroscopy: intra-articular bupivacaine does not improve pain control after preoperative peri-acetabular blockade

INTRODUCTION

Literature addressing postoperative pain management after hip arthroscopy is relatively scarce. This study aimed to assess if there was added analgesic benefit associated with postoperative intra-articular bupivacaine blockade for patients who received preoperative peri-acetabular blockade for hip arthroscopy procedures.

METHODS

52 patients were included in this comparative cohort study. Group 1 consisted of 20 patients who received preoperative peri-acetabular blockade and postoperative intra-articular blockade. The control group (Group 2), consisted of 32 patients who received only preoperative peri-acetabular blockade. Postoperative pain was recorded via visual analogue scale (VAS) pain scores, analgesic consumption, and pain diaries for 2 weeks postoperatively.

RESULTS

Postoperative VAS pain scores were significantly lower in the experimental group at the 30-minute recovery room assessment (VAS scores Group 1: 1.1; Group 2: 3.00, p = 0.034). Other than the 30-minute recovery room assessment, VAS pain scores, narcotic medication consumption, and non-narcotic analgesic consumption did not differ between the 2 groups at any time point in the study period.

CONCLUSIONS

This study did not demonstrate significant clinical benefit for patients who receive postoperative intra-articular blockade in addition to preoperative peri-acetabular blockade with bupivacaine 0.5%. We recommend the use of preoperative peri-acetabular bupivacaine blockade without intra-articular blockade postoperatively for pain control in the setting of hip arthroscopy surgery.

Minimally invasive arthroscopy of the knee using a new 2 mm device

Arthroscopy has been evolving over the last decades, whereas arthroscopic devices have not changed much. Smaller diameter arthroscopes would potentially reduce the intraoperative trauma for cartilage and soft tissues. Two-millimeter-diameter arthroscopy demonstrated very good visualization and reach of intraarticular structures-similar to knee arthroscopy using a standard arthroscopic system.

Chondrotoxic effects of intra-articular injection of local anaesthetics in the rabbit temporomandibular joint

The aim of this study was to investigate the chondrotoxic effects of a single-dose intra-articular injection of articaine, lidocaine, and bupivacaine on the rabbit temporomandibular joint (TMJ). Twenty-four rabbits were divided into four groups: control (group 1), articaine (group 2), lidocaine (group 3), and bupivacaine (group 4). Synovial fluid samples and venous blood were taken to evaluate matrix metalloproteinase 3 (MMP-3) levels. One millilitre of local anaesthetic solution was injected in the study groups and saline solution in the control group. The rabbits were euthanized after 4 weeks and the mandibular condyles and articular discs were evaluated. On histological examination, the study group samples had irregular joint surfaces, decreased collagen, and a thinner cartilage layer. Apoptotic cells were evaluated with the TUNEL method. TUNEL-positive apoptotic cell counts were higher in all study groups compared to the control group, and the difference was significant (P < 0.001). The mean preoperative serum MMP-3 level for all groups was 5.71 ± 3.33 ng/mL, while the mean postoperative level was 22.61 ± 6.36 ng/mL; this difference was significant (P < 0.001). A single-dose intra-articular injection of local anaesthetic had apoptotic effects on chondrocytes, leading to degenerative changes in the TMJ articular structures. Articaine was found to have less harmful effects than lidocaine and bupivacaine. Intra-articular injection of local anaesthetics should be limited in the TMJ because of the potential toxic effects.

Injectable thermosensitive lipo-hydrogels loaded with ropivacaine for prolonging local anesthesia

Reducing post-surgical pain can promote recovery of mobility, improve patient satisfaction, and reduce the risk of chronic pain syndrome. When managing post-surgical pain, single-injection local anesthesia is more convenient and involves lower risk to the patient than multi-injection regimes, but the effects are not long-lasting. Here we developed a system that can prolong local anesthesia after a single injection. In this system, ropivacaine (Ro) is encapsulated into liposomes, which are then loaded into Poloxamer 407-based thermosensitive hydrogels. The Ro-loaded liposome-in-gel system (Ro-Lip-Gel) is in a sol state before injection, and immediately after subcutaneous injection, it forms a gel in situ. We show through in vitro release and in vivo pharmacokinetics studies that this gel acts as a drug release depot. In rats, the initial burst release of Ro was smaller from Ro-Lip-Gel than from Ro solution or Ro-Gel, and Ro-Lip-Gel caused nerve blockade lasting four times longer than Ro solution. Ro-Lip-Gel degraded in vivo and showed good biocompatibility. Our results suggest that a liposome-in-gel system can show small initial burst release, long-term nerve blockade and good biocompatibility in vitro and in vivo. Therefore, such a system may be useful for sustained local anesthesia without systemic toxicity.

The Erector Spinae Plane Block in the Setting of Hip Arthroscopy: A Prospective Randomized Controlled Clinical Trial

PURPOSE

To investigate whether the use of an erector spinae plane block (ESPB) would reduce perioperative pain after arthroscopic therapy for femoroacetabular impingement syndrome (FAIS) and to examine the amount of additional opioids and postoperative nausea and vomiting (PONV).

METHODS

From October 2019 to October 2020, 68 patients undergoing arthroscopic therapy for FAIS were randomly allocated into 2 groups. The first group received an ultrasound-guided ESPB preoperatively with 30 mL of 0.375% ropivacaine and standard postoperative oral medication. The second group received a sham block preoperatively with 30 mL of 0.9% saline and standard postoperative oral medication. The primary endpoint was pain scores (numeric pain score out of 10) during the first 24 hours postoperatively. Secondary outcomes were opioid consumption during the first 24 hours (converted to morphine equivalents) and the incidence of PONV. Demographic and clinical characteristics were recorded for all patients. Categorial data were compared with chi-squared and Fisher's exact tests. Continuous data were compared with 2-sided t tests and Wilcoxon rank-sum tests.

RESULTS

Sixty-eight subjects consented and were successfully randomized. Reported postoperative pain was significantly lower in the ESPB group than in the control group during the first 24 hours. The opioid amount (P = .865) and postoperative nausea (P = .642) did not differ significantly between groups. No associated complications such as falls, hematomas, or muscular weakness occurred in either group.

CONCLUSION

This study demonstrates that ESPB significantly decreases pain in the first 24 hours after arthroscopic therapy for FAIS. However, there was no evidence of lower opioid consumption compared with the control group. Overall, a low and comparable rate of PONV was present. Therefore, the ESPB seems to complement a multimodal approach to perioperative pain management in hip arthroscopy.

LEVEL OF EVIDENCE

1, randomized controlled trial.

New developments in osteoarthritis pharmacological therapies

OA is an increasingly common, painful condition with complex aetiology and limited therapies. Approaches to expanding our therapeutic armamentarium have included repurposing existing therapies used for other rheumatological conditions, modifying existing OA preparations to enhance their benefits, and identifying new therapeutics. HCQ and low-dose MTX have been unsuccessful in improving hand OA pain or reducing structural progression. Anti-IL-6 and anti-GM-CSF also did not improve symptoms in hand OA trials, but IL-1 remains an intriguing target for large-joint OA, based on reduced joint replacements in a post hoc analysis from a large cardiovascular disease trial. The peripheral nociceptive pathway appears an attractive target, with mAbs to nerve growth factor and IA capsaicin demonstrating efficacy; tropomyosin receptor kinase A inhibitors are at an earlier stage of development. Limited evidence suggests pharmacological therapies can modify cartilage and bone structural progression, though evidence of synchronous symptom benefits are lacking.

Rapidly progressive idiopathic arthritis of the hip: incidence and risk factors in a controlled cohort study of 1471 patients after intra-articular corticosteroid injection

OBJECTIVE

Rapidly progressive idiopathic arthritis of the hip (RPIA) is defined by progressive joint space narrowing of > 2 mm or > 50% within 1 year. Our aims were to assess (a) the occurrence of RPIA after intra-articular steroid injection, and (b) possible risk factors for RPIA including: patient age, BMI, joint space narrowing, anesthetic and steroid selections, bone mineral density, and pain reduction after injection.

MATERIALS AND METHODS

A retrospective search of our imaging database identified 1471 patients who had undergone fluoroscopically guided hip injection of triamcinolone acetonide (Kenalog) and anesthetic within a 10-year period. Patient data, including hip DXA results and patient-reported pain scores, were recorded. Pre-injection and follow-up radiographs were assessed for joint space narrowing, femoral head deformity, and markers of osteoarthritis. Osteoarthritis was graded by Croft score. Associations between patient characteristics and outcome variables were analyzed.

RESULTS

One hundred six of 1471 injected subjects (7.2%) met the criteria for RPIA. A control group of 161 subjects was randomly selected from subjects who underwent hip injections without developing RPIA. Compared to controls, patients with RPIA were older, had narrower hip joint spaces, and higher Croft scores before injection (p < 0.05). Patients who developed RPIA did not differ from controls in sex, BMI, hip DXA T-score, anesthetic and steroid injectates, or pain improvement after injection.

CONCLUSION

We found that approximately 7% of patients undergoing steroid hip injection developed RPIA. More advanced patient age, greater joint space narrowing, and more severe osteoarthritis are risk factors for the development of RPIA after intra-articular steroid injection.

A meta-analysis on the efficacy of the ropivacaine infiltration in comparison with other dental anesthetics

OBJECTIVES

The aim of this meta-analysis was to assess the clinical efficacy and safety profile of ropivacaine in comparison with other dental anesthetics in different clinical conditions. MATERIALS AND METHODS: This meta-analysis was registered in the National Institute for Health Research PROSPERO (ID: CRD42020205580). PubMed and Scholar Google were consulted to identify clinical trials using ropivacaine in comparison with other local anesthetic drugs for any dental procedure. Articles comparing ropivacaine and other dental anesthetics were assessed with the Cochrane Collaboration's risk of bias tool. Data from reports without a high risk of bias were extracted (anesthetic and adverse effects) and analyzed using the Review Manager Software 5.3. for Windows and the Risk Reduction Calculator.

RESULTS

Ropivacaine produces a longer anesthetic time when compared with lidocaine/adrenaline (n = 260; p = 0.00001) and similar anesthesia than bupivacaine (n = 190).

CONCLUSIONS

Data of this study indicate that ropivacaine infiltration produces a longer anesthetic time when compared with lidocaine and articaine but not when compared to bupivacaine in dental procedures.

CLINICAL RELEVANCE

Ropivacaine was more effective than lidocaine for dental anesthesia. For this reason, the manufacture of a ropivacaine dental cartridge with a suitable concentration could be an important advancement for clinical practice.

Analgesia in Athletes: A Review of Commonly Used Oral and Injectable Modalities

Pain is common among athletes at all levels and the treatment of pain can be a challenging and frustrating task. The team physician needs a fundamental knowledge of analgesic strategies as it relates to athletes. It is important to understand the mechanism of action, side effect profile/associated complications, incidence of and indications for use, as well as the controversies associated with the most common analgesic medications used in sports medicine. Several "in vogue" treatment modalities, including cannabidiol, are also becoming more commonly used and are worth discussion.

The Influence of a Single Intra-Articular Lidocaine Injection on the Viability of Articular Cartilage in the Knee

OBJECTIVE

To evaluate the in vivo effect of a single intra-articular injection of local anesthetic (LA) lidocaine on the viability of articular cartilage in the intact or osteoarthritic (OA) human knees, and to measure the synovial postinjection concentration of lidocaine in the knee.

DESIGN

This study includes 3 interconnected experiments: (A) Synovial LA concentration measurement after a 2% lidocaine injection before knee arthroscopy in 10 patients by liquid chromatography-tandem mass spectrometry (LC-MS/MS). (B) Human osteochondral explants (N = 27) from intact knees procured at autopsies were incubated for different time intervals (30 minutes, 2 hours, 24 hours) with 2% lidocaine, 0.04% lidocaine (measured), or culture medium (control), and later evaluated for cell viability by LIVE/DEAD staining. (C) Ten out of 19 matched patients scheduled for knee replacement received a single intra-articular injection of 2% lidocaine approximately 30 minutes prior to the procedure; 9 patients served as control. Osteochondral samples with OA changes were harvested during surgery and analyzed for chondrocyte viability by LIVE/DEAD staining.

RESULTS

(A) The synovial LA concentration was significantly lower than the primary concentration injected: average 0.23 mg/mL (0.02%), highest measured 0.37 mg/mL (0.04%). (B) In vitro exposure to a reduced LA concentration had no significant influence on chondrocyte viability in intact cartilage explants (24-hour averages: control, 93%; 0.04% lidocaine, 92%; 2% lidocaine, 79%). (C) Viability of chondrocytes in OA knees was similar between 2% lidocaine injection (85%) and control (80%).

CONCLUSIONS

A single intra-articular knee injection of 2% lidocaine did not influence the chondrocyte viability neither in healthy nor in OA cartilage. A fast postinjection reduction of synovial LA concentration (more than 40 times) is the most likely protective mechanism.

Femoral head collapse after hip intra-articular corticosteroid injection: An institutional response to improve practice and increase patient safety

INTRODUCTION

Femoral head collapse (FHC) is a rarely reported complication of hip intra-articular corticosteroid injection (IACSI). Upon observing a high rate of FHC after hip IACSI, we sought to (1) describe how we addressed the problem through a systematic evaluation of clinical data and institutional care practices followed by process improvement efforts; and (2) report our results.

METHODS

Patients receiving hip IACSI during a 27-month period underwent retrospective review to determine the rate of FHC and to identify associated patient factors or practice shortfalls. Findings led to institution-wide interventions: (1) to improve patient/provider awareness of this association; and (2) to develop/implement practice guidelines. Rates of FHC after hip IACSI and practice patterns among providers before and after intervention were compared.

RESULTS

Initial FHC rate after hip IACSI was 20.4%. Patient-related factors included body mass index (p = 0.025), history of cancer therapy (p = 0.012), Vitamin D level (p = 0.030), and multiple injections (p = 0.004). Volume/dose of injectate and post-injection surveillance methods varied widely. Quality improvement (QI) intervention resulted in fewer treatment referrals (from 851 to 436), fewer repeat injections (mean = 1.61 to 1.37; p = 0.0006), and a 5% lower FHC rate (p = 0.1292). Variation in practice patterns persisted, so a systems-based Clinical Pathway was established.

DISCUSSION

When a high rate of FHC after hip IACSI was found to be associated with certain patient and practice factors, introduction of education materials and treatment guidelines decreased number of referrals, number of injections per patient, and FHC rate. In the absence of the systems-based Pathway, the type, dose, and volume of injectate and post-procedure follow-up remained variable.

Hyaluronic Acid as a Carrier Supports the Effects of Glucocorticoids and Diminishes the Cytotoxic Effects of Local Anesthetics in Human Articular Chondrocytes In Vitro

The current study aimed to investigate the cytotoxicity of co-administrating local anesthetics (LA) with glucocorticoids (GC) and hyaluronic acid (HA) in vitro. Human articular cartilage was obtained from five patients undergoing total knee arthroplasty. Chondrocytes were isolated, expanded, and seeded in 24-well plates for experimental testing. LA (lidocaine, bupivacaine, ropivacaine) were administered separately and co-administered with the following substances: GC, HA, and GC/HA. Viability was confirmed by microscopic images, flow cytometry, metabolic activity, and live/dead assay. The addition of HA and GC/HA resulted in enhanced attachment and branched appearance of the chondrocytes compared to LA and LA/GC. Metabolic activity was better in all LA co-administered with HA and GC/HA than with GC and only LA. Flow cytometry revealed the lowest cell viability in lidocaine and the highest cell viability in ropivacaine. This finding was also confirmed by live/dead assay. In conclusion, HA supports the effect of GC and reduces chondrotoxic effects of LA in vitro. Thereby, the co-administration of HA to LA and GC offers an alternative less chondrotoxic approach for treating patients with symptomatic osteoarthritis of the knee.

MicroRNA-183-5p protects human derived cell line SH-SY5Y cells from mepivacaine-induced injury

With the gradual recognition of the side effects of local anesthetics, the nerve injury caused by local anesthetics has received growing attention. This research intended to delve into miR-183-5p changes in mepivacaine-mediated SH-SY5Y cell injury, as well as its modulatory mechanism on cell apoptosis. RT-qPCR was adopted for assaying miR-183-5p and PDCD4 mRNA expression. Our team respectively transfected miR-183-5p mimic and inhibitor to enhance or inhibit miR-183-5p function. We employed Western blot for detecting PDCD4 protein levels, as well as flow cytometry and Hoechst 33342/PI double staining for determining cell apoptosis rate. Additionally, our crew applied an ELISA kit for measuring TNF-α, IL-1β, IL-6, and IL-8 contents. The level of reactive oxygen species (ROS) production was examined by the Image-iT LIVE Green ROS detection Kit. As well as dual-luciferase reporter experiment for verifying the targeting link of miR-183-5p with PDCD4. In mepivacaine-induced cell apoptosis in SH-SY5Y cells, miR-183-5p expression was down-regulated. TNF-α, IL-1β, IL-6, and IL-8 contents were elevated. The rate of apoptosis increased visibly, cleaved caspase-3 and Bax levels waxed, whereas Bcl-2 level waned. MiR-183-5p could alleviate the damaging impact of mepivacaine. Dual-luciferase reporter experiments demonstrated that miR-183-5p directly targeted PDCD4. Collectively, we concluded that a high concentration of mepivacaine can cause SH-SY5Y cell damage, miR-183-5p functions crucially in mepivacaine-mediated cell damage. This study provides a theoretical basis for elucidating the mechanism of mepivacaine-induced nerve cell damage, and overexpressed miR-183-5p likely become a novel strategy to combat mepivacaine-induced nerve damage.Abbreviations:miRNA: Micro RNA; PDCD4: Programmed Cell Death 4; MDA: Malondialdehyde; SOD: Superoxide Dismutase; ROS: Reactive Oxygen Species; WT: Wild Type; Mut: Mutant; UTR: Untranslated Region; IL-6: Interleukin-6; IL-1β: Interleukin-1β; TNF-α: Tumor Necrosis Factor-α; IL-8: Interleukin-8; COX-2: Cyclooxygenase-2; iNOS: inducible NOS; MEP: Mepivacaine.

Treatment of Primary Shoulder Stiffness: Results of a Survey on Surgeon Practice Patterns in Italy

Objectives  Shoulder stiffness is a condition of restricted glenohumeral range of motion (ROM), which can arise spontaneously or as consequence of a known cause. Several treatment options are available and currently no consensus has been obtained on which treatment algorithm represents the best choice for the patient. The aim of this study was to investigate surgeon practice patterns in Italy regarding treatment of primary shoulder stiffness.

Methods  A literature review was performed to identify randomized controlled trials reporting results of shoulder stiffness treatment. The following controversial or critical points in the treatment of primary shoulder stiffness were identified: modalities of physical therapy; indication for oral corticosteroid; indication and frequency for injective corticosteroid; technique and site of injection; and indication, timing, and technique for surgery. A survey composed by 14 questions was created and administrated to the members of a national association specialized in orthopaedics and sports traumatology (SIGASCOT at the time of survey completion, recently renamed SIAGASCOT after the fusion of the societies SIGASCOT and SIA).

Results  A total of 204 completed questionnaires were collected. Physical therapy was recommended by 98% of the interviewed. The use of oral corticosteroids was considered by 51%, and injections of corticosteroids by 72%. The posterior injection approach was the one preferred and a number of three was considered the upper limit for repeated injections. Injective therapy with local anesthetics and hyaluronic acid was considered by more than 20% of the interviewed. Thirty percent of the interviewed did not treat shoulder stiffness surgically.

Conclusion  Several approaches to shoulder stiffness have been proposed and high-level evidence is available to analyze and discuss their results. Several controversial points emerged both from a literature review and from this national survey. Treatment of shoulder stiffness should be tailored to the patient's clinical situation and the stage of its pathology and should aim at pain reduction, ROM restoration, functional regain, and shortening of symptoms duration, with conservative therapy remaining the mainstay of treatment.

Clinical Trial Registry Use in Orthopaedic Surgery Systematic Reviews

BACKGROUND

Results from systematic reviews and meta-analyses, which have the highest level of evidence (Level I), often drive clinical decision-making and health policy. Often, unpublished trial data are omitted from systematic reviews, raising concerns about the extent of the reliability and validity of results that have been drawn from systematic reviews. We aimed to determine the extent to which systematic review authors include searches of clinical trial registries for unpublished data when conducting systematic reviews in orthopaedic surgery.

METHODS

Systematic reviews and/or meta-analyses were gathered from the top 5 orthopaedic surgery journals based on the h5-index from Google Scholar Metrics. Systematic reviews that had been published in the Cochrane Database of Systematic Reviews, which requires the inclusion of a clinical trial registry search, served as controls. For the primary outcome, each systematic review from the top 5 orthopaedic journals was screened to determine whether the authors of each study searched for unpublished data in clinical trial registries. We then compared the rate of registry searches with those in the control group. For the secondary analysis, a search of ClinicalTrials.gov was performed for unpublished trial data for 100 randomized systematic reviews.

RESULTS

All 38 of the Cochrane systematic reviews (100%) included clinical trial registry searches, while the top 5 orthopaedic journals had only 31 of 480 studies (6.5%) that looked at clinical trial registries. The secondary analysis yielded 59 of 100 systematic review articles (59.0%) that could have included unpublished clinical trial data from ≥1 studies to their sample.

CONCLUSIONS

Systematic reviews that have been published in the top orthopaedic surgery journals seldom included a search for unpublished clinical trial data.

CLINICAL RELEVANCE

The exclusion of clinical trial registry searches potentially contributes to publication bias within the orthopaedic literature. Moving forward, systematic review authors should include clinical trial registry searches for unpublished clinical trial data to provide the most accurate representation of the available evidence for systematic reviews and meta-analyses.

In Vitro Effects of Bupivacaine on the Viability and Mechanics of Native and Engineered Cartilage Grafts

BACKGROUND

Although the toxic effects of bupivacaine on chondrocyte monolayer culture have been well described, its cellular and mechanical effects on native and engineered articular cartilage remain unclear. For the repair of articular cartilage defects, fresh autologous and allogenic cartilage grafts are commonly used, and engineered cell-based therapies are emerging. The outcome of grafting therapies aimed at repairing damaged cartilage relies largely on maintaining proper viability and mechanical suitability of the donor tissues.

PURPOSE

To investigate the in vitro effects of single bupivacaine exposure on the viability and mechanics of 2 cartilage graft types: native articular cartilage and engineered neocartilage.

STUDY DESIGN

Controlled laboratory study.

METHODS

Articular cartilage explants were harvested from the bovine stifle femoral condyles, and neocartilage constructs were engineered from bovine stifle chondrocytes using the self-assembling process, a scaffold-free approach to engineer cartilage tissue. Both explants and neocartilage were exposed to chondrogenic medium containing a clinically applicable bolus of 0.5%, 0.25%, or 0% (control) bupivacaine for 1 hour, followed by fresh medium wash and exchange. Cell viability and matrix content (collagen and glycosaminoglycan) were assessed at t = 24 hours after treatment, and compressive mechanical properties were assessed with creep indentation testing at t = 5 to 6 days after treatment.

RESULTS

Single bupivacaine exposure was chondrotoxic in both explants and neocartilage, with 0.5% bupivacaine causing a significant decrease in chondrocyte viability compared with the control condition (55.0% ± 13.4% vs 71.9% ± 13.5%; P < .001). Bupivacaine had no significant effect on matrix content for either tissue type. There was significant weakening of the mechanical properties in the neocartilage when treated with 0.5% bupivacaine compared with control, with decreased aggregate modulus (415.8 ± 155.1 vs 660.3 ± 145.8 kPa; P = .003), decreased shear modulus (143.2 ± 14.0 vs 266.5 ± 89.2 kPa; P = .002), and increased permeability (14.7 ± 8.1 vs 6.6 ± 1.7 × 10^-15 m⁴/Ns; P = .009). Bupivacaine exposure did not have a significant effect on the mechanical properties of native cartilage explants.

CONCLUSION

Single bupivacaine exposure resulted in significant chondrotoxicity in native explants and neocartilage and significant weakening of mechanical properties of neocartilage. The presence of abundant extracellular matrix does not appear to confer any additional resistance to the toxic effects of bupivacaine.

CLINICAL RELEVANCE

Clinicians should be judicious regarding the use of intra-articular bupivacaine in the setting of articular cartilage repair.

Intra-articular Morphine and Ropivacaine Injection Provides Efficacious Analgesia As Compared With Femoral Nerve Block in the First 24 Hours After ACL Reconstruction: Results From a Bone-Patellar Tendon-Bone Graft in an Adolescent Population

Background:

Opioid consumption and patient satisfaction are influenced by a surgeon’s pain-management protocol as well as the use of adjunctive pain mediators. Two commonly utilized adjunctive pain modifiers for anterior cruciate ligament (ACL) reconstruction are femoral nerve blockade and intra-articular injection; however, debate remains regarding the more efficacious methodology.

Hypothesis:

We hypothesized that intra-articular injection with ropivacaine and morphine would be found to be as efficacious as a femoral nerve block for postoperative pain management in the first 24 hours after bone–patellar tendon–bone (BTB) ACL reconstruction.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Charts were retrospectively reviewed for BTB ACL reconstructions performed by a single pediatric orthopaedic surgeon from 2013 to 2019. Overall, 116 patients were identified: 58 received intra-articular injection, and 58 received single-shot femoral nerve block. All patients were admitted for 24 hours. Pain scores were assessed every 4 hours. Morphine milligram equivalents (MMEs) consumed were tabulated for each patient.

Results:

Opioid use was 24.3 MMEs in patients treated with intra-articular injection versus 28.5 MMEs in those with peripheral block (P = .108). Consumption of MMEs was greater in the intra-articular group in the 0- to 4-hour period (7.1 vs 4.6 MMEs; P = .008). There was significantly less MME consumption in patients receiving intra-articular injection versus peripheral block at 16 to 20 hours (3.2 vs 5.6 MMEs; P = .01) and 20 to 24 hours (3.8 vs 6.5 MMEs; P < .001). Mean pain scores were not significantly different over the 24-hour period (peripheral block, 2.7; intra-articular injection, 3.0; P = .19).

Conclusion:

Within the limitations of this study, we could identify no significant difference in MME consumption between the single-shot femoral nerve block group and intra-articular injection group in the first 24 hours postoperatively. While peripheral block is associated with lower opioid consumption in the first 4 hours after surgery, patients receiving intra-articular block require fewer opioids 16 to 24 hours postoperatively. Given these findings, we propose that intra-articular injection is a viable alternative for analgesia in adolescent patients undergoing BTB ACL reconstruction.

Differences in Cytotoxicity of Lidocaine, Ropivacaine, and Bupivacaine on the Viability and Metabolic Activity of Human Adipose-Derived Mesenchymal Stem Cells

PURPOSE

We evaluated biological effects of distinct local anesthetics on human adipose-derived mesenchymal stem cells when applied to reduce periprocedural pain during mesenchymal stem cell injections.

METHODS AND MATERIALS

Metabolic activity (MTS assay), viability (Live/Dead stain), and gene expression (quantitative real-time reverse-transcriptase polymerase chain reaction) were measured in mesenchymal stem cells incubated with various concentrations of lidocaine, ropivacaine, or bupivacaine during a 12-hr time course.

RESULTS

Cell viability and metabolic activity decreased in a dose, time, and substance-specific manner after exposure to lidocaine, ropivacaine, and bupivacaine, with ropivacaine being the least cytotoxic. Cell viability decreases after brief exposure (<1.5 hrs) at clinically relevant concentrations (eg, 8 mg/ml of lidocaine, 2.5 mg/ml of ropivacaine or bupivacaine). Mesenchymal stem cells exposed to local anesthetics change their expression of mRNA biomarkers for stress response (EGR1, EGR2), proliferation (MKI67, HIST2H4A), ECM (COL1A1, COL3A1), and cell surface marker (CD105).

CONCLUSIONS

Local anesthetics are cytotoxic to clinical-grade human mesenchymal stem cells in a dose-, time-, and agent-dependent manner and change expression of ECM, proliferation, and cell surface markers. Lidocaine and bupivacaine are more cytotoxic than ropivacaine. Single-dose injections of local anesthetics may affect the biological properties of mesenchymal stem cells in vitro but may not affect the effective dose of MSCs in a clinical setting.