The Effect of Pectoral Nerve Blocks on Opioid Use and Postoperative Pain in Masculinizing Mastectomy: A Randomized Controlled Trial.

BACKGROUND: Bilateral masculinizing mastectomy is the most common gender-affirmation operation performed. Currently, there is lack of data regarding intraoperative and postoperative pain control for this population. It is the authors' aim to study the effects of the pectoral nerve (Pecs) I and II regional nerve blocks in patients undergoing masculinizing mastectomy. METHODS: A randomized, double-blind, placebo-controlled trial was performed. Patients undergoing bilateral gender-affirmation mastectomy were randomized to receive either a Pecs block with ropivacaine or placebo injection. The patient, surgeon, and anesthesia team were blinded to the allocation. Intraoperative and postoperative opioid requirements were collected and recorded as morphine milligram equivalents (MME). Participants recorded postoperative pain scores at specific time points on the day of surgery through postoperative day 7. RESULTS: Fifty patients were enrolled between July of 2020 and February of 2022. Twenty-seven were randomized to the intervention group and 23 to the control group, with 43 patients undergoing analysis. There was no significant difference in intraoperative MME between the Pecs block group and the control group (9.8 versus 11.1; P = 0.29). In addition, there was no difference in postoperative MME between the groups (37.5 versus 40.0; P = 0.72). Postoperative pain scores were also similar between the groups at each specified time point. CONCLUSIONS: There was no significant reduction in opioid consumption or postoperative pain scores in patients undergoing bilateral gender-affirmation mastectomy who received a regional anesthetic when compared with placebo. In addition, a postoperative opioid-sparing approach may be appropriate for patients undergoing bilateral masculinizing mastectomy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, I.

Development of obstetric anesthesia core competencies for USA residency programs through a Delphi process.

PURPOSE: The standard for anesthesia residency training in the USA mainly relies on the Accreditation Council for Graduate Medical Education (ACGME) Outcome Project, a framework that lacks specific directives for subspecialties including obstetric anesthesia. We aimed to identify core competencies in obstetric anesthesiology that can be adapted to different residency training programs to help improve the quality of training and accountability of the institutions within the USA. METHODS: We identified a preliminary list of competencies from review of existing competency-based obstetric anesthesia training curricula and practice guidelines. We used a modified Delphi methodology to achieve expert consensus among members of the Society for Obstetric Anesthesia and Perinatology education committee. The panellists were asked to evaluate the importance of each competency using a five-point Likert scale, with consensus after two rounds defined at 80% agreement. The responders were also asked at which level of training each competency should be attained. RESULTS: The Delphi rounds had 75% response rate and derived 94 competencies that were categorized under the six ACGME domains: patient care (38), medical knowledge (45), system-based practice (two), practice-based learning and improvement (five), interpersonal communication skills (two), and professionalism (two). CONCLUSION: We generated a residency training competency list for obstetric anesthesiology through expert consensus. This list can be used by residency training programs to develop a structured competency-based curriculum with tangible milestones, thereby reducing heterogeneity in the standard of training.

RéSUMé: OBJECTIF: La norme pour la formation en résidence en anesthésie aux États-Unis repose principalement sur le Projet de résultats (Outcome Project) de l'Accreditation Council for Graduate Medical Education (ACGME), un cadre qui ne dispose pas de directives spécifiques pour les surspécialités, notamment pour l'anesthésie obstétricale. Notre objectif était d'identifier les compétences de base en anesthésiologie obstétricale qui pourraient être adaptées aux différents programmes de formation en résidence afin d'améliorer la qualité de la formation et la responsabilisation des établissements aux États-Unis. MéTHODE: Nous avons dressé une liste préliminaire de compétences en passant en revue les programmes de formation axés sur les compétences et les lignes directrices de pratique existants en anesthésie obstétricale. Nous avons utilisé une méthodologie Delphi modifiée pour parvenir à un consensus d'expert·es parmi les membres du comité d'éducation de la Society for Obstetric Anesthesia and Perinatology. Les panélistes ont été invité·es à évaluer l'importance de chaque compétence à l'aide d'une échelle de Likert à cinq points, le consensus étant défini à 80 % d'accord après deux tours. On a également demandé aux répondant·es à quel niveau de formation chaque compétence devrait être atteinte. RéSULTATS: Les étapes du processus Delphi ont eu un taux de réponse de 75 % et ont permis de déterminer 94 compétences qui ont été classées dans les six domaines ACGME : soins aux patient·es (38), connaissances médicales (45), pratique systémique (deux), apprentissage et amélioration basés sur la pratique (cinq), compétences en communication interpersonnelle (deux) et professionnalisme (deux). CONCLUSION: Nous avons généré une liste de compétences pour la formation de résidence en anesthésiologie obstétricale grâce à un consensus d'expert·es. Cette liste peut être utilisée par les programmes de formation en résidence pour élaborer un programme structuré axé sur les compétences avec des jalons tangibles, réduisant ainsi l'hétérogénéité dans la norme de formation.

Medical Concerns in Orthobiologics Procedures.

Orthobiologics have shown immense treatment potential in many medical fields including sports medicine, musculoskeletal disorders, and pain management. As with the case of any medical procedures and treatments, there are potential side effects or caveats that physicians and patients should be cognizant of. Nevertheless, the use of orthobiologics does not seem to have consistent severe side effects and do not have increased risks with transmissible disease, immune-modulated reactions, or oncologic processes.

A survey of labour epidural practices at obstetric anesthesia fellowship programs in the United States.

PURPOSE: Labour epidural analgesia (LEA) is an evolving field. Various neuraxial techniques and dosing regimens are available to the modern obstetric anesthesia provider, allowing for significant practice variability. To begin a search for consensus on optimal care, we sought to query fellowship training practices for LEA. METHODS: We conducted an electronic survey of institutions with American Council for Graduate Medical Education-accredited obstetric anesthesiology fellowship programs. We studied the frequency of epidural initiation techniques, including combined spinal epidural (CSE), dural puncture epidural, and epidural bolus. For maintenance techniques, we appraised the use of continuous epidural infusion, programmed intermittent bolus (PIEB), and patient-controlled epidural analgesia (PCEA). RESULTS: Of 40 institutions surveyed, we received 32 responses (80% response rate). Twenty-eight of 40 (70%) were included in the analysis. A plurality of institutions (12/28; 43%) preferred CSE, and among those who used CSE, 23/27 (85%) included intrathecal opioids. A majority of institutions used protocols with PIEB (55%), while almost all (92%) used PCEA. Most participants (88%) reported using dilute concentration maintenance infusions of 0.1% bupivacaine/ropivacaine or less. CONCLUSION: Despite significant variability in LEA practice, some clear patterns emerged in our survey, including preference for opioid-containing CSE and maintenance with PIEB, PCEA, and dilute epidural solutions.

RéSUMé: OBJECTIF: L'analgésie péridurale obstétricale (APO) est un domaine en évolution. Diverses techniques neuraxiales et posologies sont disponibles pour le praticien en anesthésie obstétricale moderne, ce qui permet une variabilité significative de la pratique. Pour démarrer une recherche de consensus sur les soins optimaux, nous avons cherché à déterminer les pratiques d'APO dans le cadre de formation des fellows. MéTHODE: Nous avons réalisé une enquête électronique auprès d'établissements possédant des programmes de fellowship en anesthésiologie obstétricale accrédités par l'American Council for Graduate Medical Education. Nous avons étudié la fréquence des techniques de péridurale, notamment de rachi-péridurale combinée (RPC), de péridurale avec ponction durale et de bolus péridural. Pour les techniques de maintien, nous avons évalué l'utilisation de l'analgésie péridurale par perfusion continue, l'administration programmée de bolus périduraux (PIEB; programmed intermittent epidural bolus) et l'analgésie péridurale contrôlée par la patiente (APCP). RéSULTATS: Sur les 40 établissements sondés, nous avons reçu 32 réponses (taux de réponse de 80 %). Vingt-huit des 40 (70 %) établissements ont été inclus dans l'analyse. Plusieurs institutions (12/28; 43 %) ont répondu qu'elles préféraient la RPC, et parmi celles qui utilisaient la RPC, 23/27 (85 %) incluaient des opioïdes intrathécaux. La majorité des établissements utilisaient des protocoles avec le PIEB (55 %), tandis que presque tous (92 %) utilisaient l'APCP. La plupart des établissements participants (88 %) ont rapporté utiliser des perfusions de maintien à des concentrations diluées de bupivacaïne/ropivacaïne de 0,1 % ou moins. CONCLUSION: Malgré une variabilité significative dans la pratique de l'APO, certaines tendances claires ont émergé dans notre sondage, notamment une préférence pour les RPC contenant des opioïdes et le maintien avec un PIEB, une APCP et des solutions péridurales diluées.

Novel assessment of leukocyte-rich platelet-rich plasma on functional and patient-reported outcomes in knee osteoarthritis: a pilot study.

Background: Leukocyte-rich platelet-rich plasma (LR-PRP) has demonstrated to be beneficial for patients with knee osteoarthritis (KOA); however, reliable objective end points to accurately assess its therapeutic effects is lacking. Aim: To investigate the efficacy of LR-PRP as assessed by functional and patient-reported outcomes at early time points (6 weeks). Materials & methods: We conducted a prospective cohort study in 12 patients with diagnosed KOA (Kellgren Lawrence score of II-III), who underwent a single ultrasound-guided LR-PRP injection. Results: There was significant improvement in timed up and go, pain and quality of life scales and balance parameters. There were nonsignificant improvements in range of motion and gait parameters. Conclusion: LR-PRP demonstrates efficacy in meaningful end points for functional and patient-reported outcomes at early time points in patients with KOA.

Assessing Physical Medicine and Rehabilitation Residency Education Using the Neurological Assessment Competency Evaluation System.

ABSTRACT: Competent neurologic examination and clinical skills are essential components in the care for patients in acute hospital and rehabilitation settings. To enhance the evaluation and education of Physical Medicine and Rehabilitation residents, the authors developed an educational objective structured clinical examination, the Neurological Exam Assessment Competency Evaluation System, and gathered 2 yrs of baseline data. The Neurological Exam Assessment Competency Evaluation System consisted of nine 9-min examination stations, seven with written clinical scenario with instructions for junior residents to complete the appropriate examination (stations: Altered Mental Status, Mild Traumatic Brain Injury, Dementia, Stroke, Falls, and the International Standards for Neurological Classification of Spinal Cord Injury Sensory and Motor Examinations). Examinees provided written responses to posed questions for the other two stations-Modified Ashworth Scale and brachial plexus. The assessment tools for this examination were designed for residency programs to evaluate the basic competencies as outlined by the Accreditation Council for Graduate Medical Education and Physical Medicine and Rehabilitation milestones. Based on the feedback received from the examinees and examiners, the Neurological Exam Assessment Competency Evaluation System can serve as an educational objective structured clinical examination for the improvement of trainee core competencies.

DNAzymes for amine and peptide lysine acylation.

DNAzymes were previously identified by in vitro selection for a variety of chemical reactions, including several biologically relevant peptide modifications. However, finding DNAzymes for peptide lysine acylation is a substantial challenge. By using suitably reactive aryl ester acyl donors as the electrophiles, here we used in vitro selection to identify DNAzymes that acylate amines, including lysine side chains of DNA-anchored peptides. Some of the DNAzymes can transfer a small glutaryl group to an amino group. These results expand the scope of DNAzyme catalysis and suggest the future broader applicability of DNAzymes for sequence-selective lysine acylation of peptide and protein substrates.

Leukocyte-rich platelet-rich plasma application in post-traumatic osteoarthritis with popliteal cyst: a case report.

Aim: To describe the successful treatment of a Baker's cyst in the setting of post-traumatic osteoarthritis using ultrasound-guided injection of platelet-rich plasma. Setting: Outpatient sports clinic. Patient: 29-year old male basketball player. Case description: The patient presented with 2-months history of right knee pain, 17 months after undergoing right knee anterior cruciate ligament reconstruction surgery. Exam revealed medial joint line and medial collateral ligament tenderness with posterior knee swelling. After aspiration, a corticosteroid injection was administered with temporary symptom relief. Diagnostic ultrasound examination confirmed the Baker's cyst. The patient then underwent two serial leukocyte-rich platelet-rich plasma injections into his right knee. Results: The patient reported complete resolution of pain and cyst size. Conclusion: Leukocyte-rich platelet-rich plasma may be considered as a treatment option for patients with Baker's cysts in the setting of post-traumatic osteoarthritis.

Ehlers-Danlos Syndrome: An Analysis of the Current Treatment Options.

BACKGROUND: Ehlers-Danlos syndrome (EDS) is a multifaceted disease that can present with a variety of types of pain. Unfortunately, both the mechanisms and treatments for pain are poorly understood. The proposed treatments for the various musculoskeletal pain syndromes in EDS have had variable success, and it becomes much more imperative to better define and evaluate the current treatment modalities in treating this debilitating disease. OBJECTIVES: The purpose of this study was to investigate the currently available treatment modalities for patients with EDS and their efficacies in pain and symptom relief. STUDY DESIGN: Retrospective cohort study. SETTING: Institutional physical medicine and rehabilitation primary care clinic. METHODS: All patients were seen between January 2015 and April 2019, in which 98 patients with EDS were identified through retrospective chart review. Institutional review board approval was obtained, and all patients provided written consent to be included in the study. We reviewed various treatment modalities, including complimentary/alternative treatments, opioids/opioid-like medications, nonsteroidal antiinflammatory drugs, physical therapy, occupational therapy, muscle relaxants, neuropathic modulators, steroids, surgery/procedures, and acetaminophen. Treatment methods were extracted from individual patient charts, and efficacy was grouped into 3 categories: improvement, no effect, or worsened symptoms. RESULTS: The most common treatments used were complimentary/alternative treatments (n = 88). Occupational therapy and bracing were the most effective options with 70% of patients reporting improvement. Neuropathic modulators were the least well tolerated with 47% of patients reporting adverse effects. LIMITATIONS: Men were a small percentage of the study. Patients were not randomized, and pain score reporting was subjective. Patient data were extracted from a single practice setting. Timing and symptom onset were not measured. CONCLUSIONS: There is a relative paucity of published literature regarding the various treatment methods for EDS. Although our study is able to identify positive and negative trends with certain modalities, it is vital to understand that EDS is not a uniform diagnosis among patients, and that a combination of several different treatments usually is needed for optimal symptom control. Further research and investigation are necessary to develop a comprehensive treatment database for this complex condition. KEY WORDS: Ehlers-Danlos syndrome, pain, hypermobility, arthralgia, subluxation, genetic, physical therapy, interventional pain.

Effects of Antiplatelet and Nonsteroidal Anti-inflammatory Medications on Platelet-Rich Plasma: A Systematic Review.

BACKGROUND: Platelet-rich plasma (PRP) has wide applications in orthopaedic care. Its beneficial effects are attributed to the growth factor profile from the platelet secretome. In theory, these effects would be diminished by medications that inhibit platelet activation and/or the subsequent release of growth factors. PURPOSE: To determine whether commonly used antiplatelets, nonsteroidal anti-inflammatory drugs (NSAIDs), or anticoagulant medications affect platelet growth factor release in PRP. STUDY DESIGN: Systematic review; Level of evidence, 2. METHOD: A systematic review of the literature related to antiplatelet, anti-inflammatory, and anticoagulant drugs was performed following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We used the Downs and Black objective quality scoring system. The literature search consisted of PubMed and Cochrane Library databases. Search terms consisted of 1 item selected from "platelet-rich plasma," "platelet-derived growth factor," and "platelet-rich plasma AND growth factor" combined with 1 item from "antiplatelet," "aspirin," "anticoagulant," and "NSAID." Only studies published within the past 25 years were included. RESULTS: A total of 15 studies met the inclusion criteria: 7 studies detected no significant decrease in growth factors or mitogenesis, whereas 6 detected a decrease with antiplatelet agents, 1 detected mixed results with an antiplatelet agent, and 1 had mixed results with an antiplatelet agent/vasodilator. In terms of PRP activation, all 3 studies assessing collagen, the 2 studies analyzing adenosine diphosphate alone, and the 1 study investigating arachidonic acid found a decrease in growth factor concentration. CONCLUSION: Antiplatelet medications may decrease the growth factor release profile in a cyclooxygenase 1- and cyclooxygenase 2-dependent manner. Eight of 15 studies found a decrease in growth factors or mitogenesis. However, more studies are needed to comprehensively understand antiplatelet effects on the PRP secretome.

Systemic manifestations of Ehlers-Danlos syndrome.

Ehlers-Danlos syndrome (EDS) is a multifaceted debilitating disease. Affected patients are at risk for complications such as joint hypermobility and cardiac disease, but the prevalence, course, and management of these conditions are not well understood. The objective of this retrospective cohort study was to investigate the demographic characteristics and systemic manifestations in EDS. We performed a retrospective analysis of 98 EDS patients seen in a physical medicine and rehabilitation clinic between January 2015 and April 2019. Charts were reviewed for demographic information, subtype of EDS, characteristics of musculoskeletal pain, and presence of certain systemic comorbid diagnoses: autonomic dysfunction, headaches/migraines, gastrointestinal conditions, cardiovascular anomalies, mast cell activation syndrome, and temporomandibular joint dysfunction. Of 98 patients, 75 were diagnosed with EDS-hypermobile type (EDS-HT); 94 patients were women, and the mean age was 36.7 years. On average, each patient reported involvement of 5.4 joints, with the shoulder, knee, and lumbar spine as the most common. The average number of comorbid systemic conditions was 2.8, of which autonomic dysfunction was the most common. This study aims to provide a better understanding of this disease to promote earlier and more accurate diagnoses to guide treatment and prevent complications.

Pediatric to Adult Transition in Sickle Cell Disease: Survey Results from Young Adult Patients.

BACKGROUND/AIMS: We surveyed sickle cell disease (SCD) patients who transitioned from pediatric care at Texas Children's Hematology Center (TCHC) to adult care to determine the characteristics of patients with an adult SCD provider, continuation rates of pre-transition therapies, and patient perceptions of the transition process. METHODS: A cross-sectional study was conducted by telephone survey of 44 young adults with SCD, aged 19-29 years, who transitioned from TCHC to adult care within the last 15 years. RESULTS: Findings of the 23-item questionnaire revealed that transitioned patients with current adult providers (68.2%) were more likely to have seen a provider within 6 months of transition (p = 0.023) and to have been on hydroxyurea and/or monthly blood transfusions pre-transition (p = 0.021) than transitioned patients without a provider; 83% of patients on pre-transition hydroxyurea reported continuing hydroxyurea after transition. Transition challenges included inadequate preparation, difficulty finding knowledgeable adult providers, and lack of healthcare insurance/coverage. CONCLUSION: Transition to adult providers is predicted by establishing care with an adult SCD provider within 6 months of transition and being on pre-transition disease-modifying therapy. Transition may be improved if pediatric hematology centers assist and verify adult provider contact within 6 months of transition and engage patients of all disease severity during transition.

Content Evaluation of Physical Medicine and Rehabilitation Residency Websites.

BACKGROUND: Prospective Physical Medicine and Rehabilitation (PM&R) applicants commonly view residency program websites to make informed decisions about where to submit their applications. To our knowledge, this is the first comprehensive review of the availability and accessibility of online content for PM&R residency programs. OBJECTIVE: To evaluate the comprehensiveness of PM&R residency websites to inform prospective applicants about the information readily available to them and identify deficient areas for program directors to address. DESIGN: Cross-sectional analysis of residency program websites using quantitative and descriptive statistics. SETTING: World Wide Web (Internet). SUBJECTS: 87 PM&R civilian residency program websites listed on the Fellowship and Residency Electronic Interactive Database (FREIDA). MAIN OUTCOME MEASUREMENTS: The presence or absence of 25 predetermined criteria on residency program websites. RESULTS: The individual residency program websites had a mean ± SD of 12.3 ± 4.3 (49.1%) of the 25 criteria sought. The programs ranged from having as few as one to as many as 19 of the 25 criteria. Twenty programs had 9 or fewer criteria, 35 programs had 10 to 14 criteria, 31 programs had 15 to 18 criteria, and one program had 19 criteria available online. No PM&R residency website had all 25 criteria. There was a significant association between a program's Doximity ranking as top 20 or not and the citation of published research projects by faculty on a PM&R website (P = .026), but the other 24 criteria had no significant associations. CONCLUSIONS: Most PM&R residency websites currently do not include comprehensive information about their programs for prospective applicants.

Effects of Aspirin on Growth Factor Release From Freshly Isolated Leukocyte-Rich Platelet-Rich Plasma in Healthy Men: A Prospective Fixed-Sequence Controlled Laboratory Study.

BACKGROUND: The benefits of platelet-rich plasma (PRP) are believed to be in part dependent on growth factor release after platelet activation. Platelet activation is complex and involves multiple mechanisms. One important mechanism is driven by cyclooxygenase 1 (COX-1)-mediated conversion of arachidonic acid (AA) to precursor prostaglandins that then mediate proinflammatory responses that trigger growth factor release. Acetylsalicylic acid (ASA; also known as aspirin) is known to irreversibly inhibit COX-1, thereby blocking AA-mediated signaling; however, it is unclear whether ASA use alters growth factor release from freshly isolated PRP. PURPOSE: To assess the effects of low-dose ASA use on activation of growth factor release from freshly isolated human PRP via AA and thrombin (TBN). STUDY DESIGN: Controlled laboratory study. METHODS: Twelve healthy men underwent blood collection and leukocyte-rich PRP (LR-PRP) preparation through a double-spin protocol to obtain baseline whole blood and PRP counts the same day. PRP was aliquoted into 3 groups: nonactivated, AA activated, and TBN activated. Immediately after activation, the concentrations of transforming growth factor ß1 (TGF-ß1), vascular endothelial growth factor (VEGF), and platelet-derived growth factor AB (PDGF-AB) were measured using enzyme-linked immunosorbent assays (ELISAs). The same 12 participants were then placed on an 81-mg daily dose of oral ASA for 14 days. Repeat characterization of whole blood and PRP analyses was done on day 14, followed by repeat ELISAs of growth factors under the same nonactivated and activated settings as previously stated. RESULTS: Fourteen days of daily ASA had no effect on the number of platelets and leukocytes measured in whole blood and LR-PRP. Compared with nonactivated LR-PRP, AA- and TBN-mediated activation led to significant release of VEGF and PDGF-AB. In contrast, release of TGF-ß1 from LR-PRP was observed only with activation by AA, not with TBN. Consistent with its inhibitory role in AA signaling, ASA significantly inhibited AA-mediated release of all 3 growth factors measured in this study. Although ASA had no effect on TBN-mediated release of VEGF and TGF-ß1 from LR-PRP, ASA did partially block TBN-mediated release of PDGF-AB, although the mechanism remains unclear. CONCLUSION: Daily use of low-dose ASA reduces VEGF, PDGF-AB, and TGF-ß1 expression in freshly isolated human LR-PRP when activated with AA. CLINICAL RELEVANCE: Reduction in growth factor release attributed to daily use of low-dose ASA or other COX inhibitors can be mitigated when PRP samples are activated with TBN. Clinical studies are needed to determine whether activation before PRP injection is needed in all applications where ASA is in use and to what extent ASA may inhibit growth factor release in vivo at the site of injury.

Chondrotoxic Effects of Local Anesthetics on Human Knee Articular Cartilage: A Systematic Review.

OBJECTIVE: To review the current literature on the effects of intraarticular local anesthetics on human knee articular cartilage. LITERATURE SURVEY: PubMed; MEDLINE; SCOPUS; PEDro; CINAHL databases (1/1990-06/1/2018) were searched for local anesthetic effects on human knee articular cartilage. METHODOLOGY: Sixteen studies met the inclusion criteria, with outcome measures assessing chondrocyte viability, morphology, and histology. A systematic review was performed using PRISMA guidelines. SYNTHESIS: Seven studies were identified evaluating lidocaine, with five of them demonstrating statistically significant chondrotoxic effects. Fourteen studies examined bupivacaine, with all but one study demonstrating a chondrotoxic effect. Eight studies examined ropivacaine and found a dose-dependent chondrotoxicity starting at 0.75%. Two studies evaluated levobupivacaine showing chondrotoxicity, with one study showing it to be more chondrotoxic than bupivacaine. One study looked at mepivacaine and showed it to have more chondrotoxicity than ropivacaine. When studied the chondrotoxicity was found to be both dose and time dependent. Also, the addition of corticosteroids appeared to worsen the chondrotoxic effects. CONCLUSIONS: Lidocaine, bupivacaine, ropivacaine, levobupivacaine, and mepivacaine were reported to have dose- and time-dependent deleterious effects on chondrocytes that appeared to be made worse by the coadministration of corticosteroids. Ropivacaine at concentrations of 0.5% or less was found to be the least chondrotoxic anesthetic. LEVEL OF EVIDENCE: I.

Mesoscale modelling of environmentally responsive hydrogels: emerging applications.

Stimuli-sensitive hydrogels are an exciting class of materials with widespread potential for use in engineering and biomedical applications. The design of advanced functional devices using hydrogels requires an in-depth understanding of the physics and behaviour of such materials. While theoretical tools exist, they are often limited to simple cases. Thus, computational methods are necessary to model the complex unsteady physics of hydrogels with high fidelity. Mesoscale modelling is an emerging approach that enables simulations of polymeric structures at length and time scales in between those of molecular dynamics and continuum methods. In this feature article, we review various computational approaches to model responsive hydrogels and specifically focus on dissipative particle dynamics (DPD), a particle-based mesoscale method. We discuss several approaches for modelling cross-linked polymer networks in DPD, and describe recent applications of DPD to modelling hydrogel systems.