Protocolized reduction of non-resuscitation fluids versus usual care in septic shock patients (REDUSE): a randomized multicentre feasibility trial

BACKGROUND/PURPOSE

Non-resuscitation fluids constitute the majority of fluid administered for septic shock patients in the intensive care unit (ICU). This multicentre, randomized, feasibility trial was conducted to test the hypothesis that a restrictive protocol targeting non-resuscitation fluids reduces the overall volume administered compared with usual care.

METHODS

Adults with septic shock in six Swedish ICUs were randomized within 12 h of ICU admission to receive either protocolized reduction of non-resuscitation fluids or usual care. The primary outcome was the total volume of fluid administered within three days of inclusion.

RESULTS

Median (IQR) total volume of fluid in the first three days, was 6008 ml (interquartile range [IQR] 3960-8123) in the restrictive fluid group (n = 44), and 9765 ml (IQR 6804-12,401) in the control group (n = 48); corresponding to a Hodges-Lehmann median difference of 3560 ml [95% confidence interval 1614-5302]; p < 0.001). Outcome data on all-cause mortality, days alive and free of mechanical ventilation and acute kidney injury or ischemic events in the ICU within 90 days of inclusion were recorded in 98/98 (100%), 95/98 (98%) and 95/98 (98%) of participants respectively. Cognition and health-related quality of life at six months were recorded in 39/52 (75%) and 41/52 (79%) of surviving participants, respectively. Ninety out of 134 patients (67%) of eligible patients were randomized, and 15/98 (15%) of the participants experienced at least one protocol violation.

CONCLUSION

Protocolized reduction of non-resuscitation fluids in patients with septic shock resulted in a large decrease in fluid administration compared with usual care. A trial using this design to test if reducing non-resuscitation fluids improves outcomes is feasible.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT05249088, 18 February 2022. https://clinicaltrials.gov/ct2/show/NCT05249088.

Proceedings of the 2023 Viral Clearance Symposium, Session 4: Continuous Processing

The continuous processing session at the 2023 Viral Clearance Symposium (VCS) focused on understanding how to effectively design viral clearance operations for use in continuous processes and methods to perform viral clearance studies. In this session, an approach to directly address control considerations with operating continuous-flow reactors for low pH viral inactivation was presented. Continuous-flow low pH incubation chamber design and implications for residence time determination were discussed. Additionally, viral clearance capability between batch operation and connected operation were demonstrated to be comparable for a connected bind-elute chromatography and flow-through chromatography step. Overall, this session provided additional scientific knowledge to support viral clearance strategies when implementing a continuous manufacturing process.

Recycling transplanted organs: An exceptional case and literature review

BACKGROUND

Recycling transplant kidneys, in other words using an allograft which has previously been transplanted in one recipient for transplant in a second recipient, can be a source of opportunity for expanding the pool of available grafts in the United States and beyond.

SUMMARY

We describe a case of renal transplantation from a donor who had undergone a kidney transplant 3 years prior and had good graft function at the time of procurement. The recipient underwent transplantation uneventfully and to date has demonstrated excellent graft function. We also include a literature review of reported cases of recycled/retransplanted kidneys.

KEY MESSAGES

-Recycling transplanted kidneys is a largely untapped resource which could help decrease the transplant waitlist. -Utilizing such kidneys does need special considerations in terms of procurement technique, backtable, crossmatch, recipient selection and follow-up.

Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

Spontaneous Resolution of Pediatric Varus Ankle Deformity: A Case Report

Introduction

Distal tibia fractures are a common cause of physeal injuries that can subsequently cause deformity in pediatric populations. Limited literature exists supporting treatment strategies for varus deformities. In this study, we illustrate a unique case of premature physeal closure complicated by development of a varus ankle deformity treated with navigation guided physeal bar resection that spontaneously resolved without the requirement for guided growth.

Case Report

A 6-year-old female presented to our clinic after development of a right ankle varus deformity measuring 14°. She had sustained a right Salter Harris type 3 distal tibia fracture 10 months prior and underwent fixation at an external facility. After undergoing navigation guided physeal bar resection, resolution of her deformity occurred without the use of guided growth.

Conclusion

Spontaneous resolution of an ankle deformity is possible after a physeal bar resection. However, in these technically demanding procedures, it is important to optimize accuracy and results using preoperative bar mapping and intraoperative three-dimensional navigation.

Assessing ChatGPT's orthopedic in-service training exam performance and applicability in the field

BACKGROUND

ChatGPT has gained widespread attention for its ability to understand and provide human-like responses to inputs. However, few works have focused on its use in Orthopedics. This study assessed ChatGPT's performance on the Orthopedic In-Service Training Exam (OITE) and evaluated its decision-making process to determine whether adoption as a resource in the field is practical.

METHODS

ChatGPT's performance on three OITE exams was evaluated through inputting multiple choice questions. Questions were classified by their orthopedic subject area. Yearly, OITE technical reports were used to gauge scores against resident physicians. ChatGPT's rationales were compared with testmaker explanations using six different groups denoting answer accuracy and logic consistency. Variables were analyzed using contingency table construction and Chi-squared analyses.

RESULTS

Of 635 questions, 360 were useable as inputs (56.7%). ChatGPT-3.5 scored 55.8%, 47.7%, and 54% for the years 2020, 2021, and 2022, respectively. Of 190 correct outputs, 179 provided a consistent logic (94.2%). Of 170 incorrect outputs, 133 provided an inconsistent logic (78.2%). Significant associations were found between test topic and correct answer (p = 0.011), and type of logic used and tested topic (p =  < 0.001). Basic Science and Sports had adjusted residuals greater than 1.96. Basic Science and correct, no logic; Basic Science and incorrect, inconsistent logic; Sports and correct, no logic; and Sports and incorrect, inconsistent logic; had adjusted residuals greater than 1.96.

CONCLUSIONS

Based on annual OITE technical reports for resident physicians, ChatGPT-3.5 performed around the PGY-1 level. When answering correctly, it displayed congruent reasoning with testmakers. When answering incorrectly, it exhibited some understanding of the correct answer. It outperformed in Basic Science and Sports, likely due to its ability to output rote facts. These findings suggest that it lacks the fundamental capabilities to be a comprehensive tool in Orthopedic Surgery in its current form.

LEVEL OF EVIDENCE

II.

Spiritual Well-Being and Related Factors in Children With Cancer

Introduction: There are specific gaps that call for empirical research in the experiences of spiritual well-being among children 12 years old and younger with cancer. Understanding these relationships can help to develop holistic and family centered care in pediatric oncology wards. This study assessed the spiritual well-being of children with cancer in association with their general well-being, happiness, quality of life, pain intensity, and personal characteristics. Method: The data were collected in Lithuania between June 2020 and November 2021. Children with cancer (N = 81) who were hospitalized at pediatric oncology-hematology centers participated in the study. Inclusion criteria were age (from 5 to 12 years old), diagnosis of oncologic disease for the first time, and absence of other chronic diseases. The instruments used were: Feeling Good, Living Life; Oxford Happiness Questionnaire, Short Form; Well-Being Index; PedsQL™3.0 Cancer Module, and a Wong-Baker FACES® Pain Rating Scale. Results: Communal and personal domains of spiritual well-being had the highest scores among pediatric oncology patients while both dimensions of the transcendental domain scored lowest. Age, level of education, and family composition revealed differences in children's spiritual health, happiness, and well-being, and church attendance was significant for overall spiritual well-being and its transcendental domain on lived experience dimension. Happiness had the strongest effect on all four domains of spiritual well-being. Discussion: Children emphasized the importance of spiritual aspects to feel better to a greater extent than they experienced in their lives. Despite their young age, children were familiar with family traditions, that is, religious practice and church attendance, and followed them in a particular sociocultural context.

Three-Dimensional Printed Cellulose for Wound Dressing Applications

Wounds are skin tissue damage due to trauma. Many factors inhibit the wound healing phase (hemostasis, inflammation, proliferation, and alteration), such as oxygenation, contamination/infection, age, effects of injury, sex hormones, stress, diabetes, obesity, drugs, alcoholism, smoking, nutrition, hemostasis, debridement, and closing time. Cellulose is the most abundant biopolymer in nature which is promising as the main matrix of wound dressings because of its good structure and mechanical stability, moisturizes the area around the wound, absorbs excess exudate, can form elastic gels with the characteristics of bio-responsiveness, biocompatibility, low toxicity, biodegradability, and structural similarity with the extracellular matrix (ECM). The addition of active ingredients as a model drug helps accelerate wound healing through antimicrobial and antioxidant mechanisms. Three-dimensional (3D) bioprinting technology can print cellulose as a bioink to produce wound dressings with complex structures mimicking ECM. The 3D printed cellulose-based wound dressings are a promising application in modern wound care. This article reviews the use of 3D printed cellulose as an ideal wound dressing and their properties, including mechanical properties, permeability aspect, absorption ability, ability to retain and provide moisture, biodegradation, antimicrobial property, and biocompatibility. The applications of 3D printed cellulose in the management of chronic wounds, burns, and painful wounds are also discussed.

Leveraging ecological momentary assessment to understand variability in food parenting practices within a low-income racially/ethnically diverse sample of parents of preschoolers

Children's eating behaviors are shaped significantly by their home food environment, including exposure to food parenting practices. The current study leveraged ecological momentary assessment (EMA) to describe how food parenting practices used to feed preschoolers (n = 116) differed across contextual factors around eating, including type of eating occasion (i.e., meals vs. snacks), day of the week (i.e., weekend vs. weekday), who initiated the meal (parent vs. child), emotional climate of the eating occasion. Parent perceptions of how well the eating occasion went, including how well the child ate and whether the food parenting practices worked as intended were also explored. Parent use of specific food parenting practices, situated within four higher-order domains (i.e., structure, autonomy support, coercive control, indulgent), was found to differ by type of eating occasion; parents engaged in a higher proportion of structure practices at meals than at snacks. Use of specific food parenting practices differed by mealtime emotional climate; parent use of structure and autonomy support was associated with eating occasions described as relaxed, enjoyable, neutral, and fun. Finally, parent perception of how well the child ate differed by use of specific food parenting practices; during eating occasions when parent's felt their child ate "not enough", they used less autonomy support and more coercive control compared to eating occasions where the child ate "enough and a good balance." Leveraging EMA allowed for increased understanding of the variability in food parenting practices and contextual factors. Findings may be utilized to inform the development of larger-scale studies seeking to understand why parents choose specific approaches to feeding their children, as well as the impact of various approaches to child feeding on child health outcomes.

A Cohort Study of Mental Health Services Utilization Following a First Pregnancy Abortion or Birth

Objective

To determine whether exposure to a first pregnancy outcome of induced abortion, compared to a live birth, is associated with an increased risk and likelihood of mental health morbidity.

Materials and methods

Participants were continuously eligible Medicaid beneficiaries age 16 in 1999, and assigned to either of two cohorts based upon the first pregnancy outcome, abortion (n = 1331) or birth (n = 3517), and followed through to 2015. Outcomes were mental health outpatient visits, inpatient hospital admissions, and hospital days of stay. Exposure periods before and after the first pregnancy outcome, a total of 17 years, were determined for each cohort.

Findings

Women with first pregnancy abortions, compared to women with births, had higher risk and likelihood of experiencing all three mental health outcome events in the transition from pre- to post-pregnancy outcome periods: outpatient visits (RR 2.10, CL 2.08-2.12 and OR 3.36, CL 3.29-3.42); hospital inpatient admissions (RR 2.75, CL 2.38-3.18 and OR 5.67, CL 4.39-7.32); hospital inpatient days of stay (RR 7.38, CL 6.83-7.97 and OR 19.64, CL 17.70-21.78). On average, abortion cohort women experienced shorter exposure time before (6.43 versus 7.80 years), and longer exposure time after (10.57 versus 9.20 years) the first pregnancy outcome than birth cohort women. Utilization rates before the first pregnancy outcome, for all three utilization events, were higher for the birth cohort than for the abortion cohort.

Conclusion

A first pregnancy abortion, compared to a birth, is associated with significantly higher subsequent mental health services utilization following the first pregnancy outcome. The risk attributable to abortion is notably higher for inpatient than outpatient mental health services. Higher mental health utilization before the first pregnancy outcome for birth cohort women challenges the explanation that pre-existing mental health history explains mental health problems following abortion, rather than the abortion itself.

Prevalence of early postpartum depression and associated risk factors among selected women in southern Malawi: a nested observational study

BACKGROUND

The birth of a child should be a time of celebration. However, for many women, childbirth represents a time of great vulnerability to becoming mentally unwell, a neglected maternal morbidity. This study aimed to determine the prevalence of early postpartum depression (PPD) and its associated risk factors among women giving birth at health facilities in southern Malawi. Identifying women vulnerable to PPD will help clinicians provide appropriately targeted interventions before discharge from the maternity ward.

METHOD

We conducted a nested cross-sectional study. Women were screened for early PPD using a locally validated Edinburgh Postpartum Depression Scale (EPDS) as they were discharged from the maternity ward. The prevalence of moderate or severe (EPDS ≥ 6) and severe (EPDS ≥ 9) PPD was determined, including 95% confidence intervals (CI). Data on maternal age, education and marital status, income source, religion, gravidity, and HIV status, among others, were collected during the second trimester of pregnancy, and obstetric and infant characteristics during childbirth were examined as potential risk factors for early PPD using univariable and multivariable logistic regression analyses.

RESULTS

Data contributed by 636 women were analysed. Of these women, 9.6% (95% CI; 7.4-12.1%) had moderate to severe early PPD using an EPDS cut-off of ≥ 6, and 3.3% (95% CI; 2.1-5.0%) had severe early PPD using an EPDS cut-off of ≥ 9. Multivariable analyses indicated that maternal anaemia at birth (aOR; 2.65, CI; 1.49-4.71, p-value; 0.001) was associated with increased risk for moderate and/or severe early PPD, while live birth outcome (aOR; 0.15, 95% CI; 0.04-0.54, p-value; 0.004), being single compared to divorced/widowed (aOR; 0.09, 95% CI; 0.02-0.55, p-value; 0.009), and lower education level (aOR; 0.36, 95% CI; 0.20-0.65, p-value; 0.001) were associated with decreased risk. Being HIV positive (aOR; 2.88, 95% CI; 1.08-7.67, p-value; 0.035) was associated with severe PPD only.

CONCLUSION

The prevalence of early PPD was slightly lower in our selected sample compared to previous reports in Malawi and was associated with maternal anaemia at birth, non-live birth, being divorced/widowed and HIV-positive status. Therefore, health workers should screen for depressive symptoms in women who are at increased risk as they are discharged from the maternity ward for early identification and treatment.

Procalcitonin as a Predictor of Septic Knee Arthritis: A Retrospective Cohort Study

INTRODUCTION

Differentiating septic arthritis from aseptic arthritis (AA) of the knee is difficult without arthrocentesis. Although procalcitonin (PCT) has shown diagnostic value in identifying bacterial infections, it has not been established as a reliable marker for identifying septic arthritis (SA). Recent studies have shown promise in the use of PCT as a useful systemic marker for identifying septic arthritis versus AA. This observational retrospective review compares PCT with routine inflammatory markers as a tool for differentiating septic arthritis versus AA in patients with acute, atraumatic knee pain.

METHODS

Fifty-three consecutive patients (24 SA, 29 AA) were retrospectively reviewed at one institution with concern for SA. SA was diagnosed based on a physical examination, laboratory markers, and arthrocentesis. Laboratory indices were compared between the septic arthritis and AA groups. Data analysis was conducted to define sensitivity and specificity. Receiver operator characteristic curve analysis and regression were conducted to determine the best marker for acute SA of the knee.

RESULTS

Using multiple logistic regression, bacteremia (OR 6.75 ± 5.75) was determined to be the greatest predictor of SA. On linear regression, concomitant bacteremia (coef 3.07 ± 0.87), SA (coef 2.18 ± 0.70), and the presence of pseudogout crystals (coef 1.80 ± 0.83) on microscopy predicted an increase in PCT. Using a PCT cutoff of 0.25 ng/mL yields a sensitivity of 91.7% and specificity of 55.2% for predicting SA; however, the ideal cutoff in our series was 0.32 ng/mL with a sensitivity of 79.2% and specificity of 72.4%. PCT was superior to the white blood cell count, erythrocyte sedimentation rate, and C-reactive protein in the area under the receiver-operating characteristic curve analysis.

DISCUSSION

Procalcitonin seems to be the most sensitive and specific systemic marker in differentiating septic from AA.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

The effect of decellularisation on the real time mechanical fatigue of porcine aortic heart valve roots

Decellularised heart valve roots offer a promising option for heart valve replacement in young patients, having the potential to remodel and repair. Replacement heart valves have to undergo billions of opening and closing cycles throughout the patient’s lifetime. Therefore, understanding the effect of cyclic loading on decellularised heart valve roots is important prior to human implantation. The aim of this preliminary study was to investigate the influence of low concentration sodium dodecyl sulphate (SDS) decellularisation treatment on the in vitro real time mechanical fatigue of porcine aortic heart valve roots under physiological real time cyclic loading conditions. This required a specific real time in vitro method to be developed, since previous methods relied on accelerated testing, which is non-physiological, and not appropriate for valve replacement materials that exhibit time dependent characteristics. The effects of the real time fatigue on hydrodynamic function and mechanical properties of the heart valve roots were assessed. The mechanical fatigue of decellularised porcine aortic heart valve roots (n = 6) was assessed and compared to cellular porcine aortic heart valve roots (n = 6) in a modified Real time Wear Tester (RWT) at a physiological frequency and under cyclic pressure conditions for a maximum of 1.2 million cycles. Periodically, the heart valve roots were removed from the RWT to assess the influence of cyclic loading on valve competency (static leaflet closure). At the end of testing further hydrodynamic performance parameters were ascertained, along with determination of leaflet material properties. A real time mechanical fatigue assessment method was developed and applied; with two cellular and two decellularised porcine aortic leaflets in different heart valve roots showing tears in the belly region. The decellularised aortic heart valve roots exhibited comparative functionality to the cellular heart valve roots under in vitro static and pulsatile hydrodynamic conditions. However, the material properties of the decellularised aortic leaflets were significantly altered following cyclic fatigue assessment and showed increases in elastin and collagen phase slopes and ultimate tensile strength compared to the cellular porcine aortic leaflets in the circumferential direction. This preliminary study demonstrated that low concentration SDS decellularised porcine aortic heart valve roots can withstand physiological cyclic deformations up to 1.2 million cycles in a RWT whilst maintaining their overall hydrodynamic function and leaflet mechanical properties. This is the first full report of preclinical mechanical fatigue assessment of decellularised porcine aortic heart valve roots under physiological real time conditions.

Interventions to prevent preterm delivery in women with short cervix before fetoscopic laser surgery for twin-twin transfusion syndrome

OBJECTIVE

Preoperative short cervical length (CL) remains a major risk factor for preterm birth after laser surgery for twin-twin transfusion syndrome (TTTS), but the optimal intervention to prolong pregnancy remains elusive. The objective of this study was to compare secondary methods for the prevention of preterm birth in twin pregnancies with TTTS undergoing fetoscopic laser photocoagulation (FLP), in the setting of a short cervix at the time of FLP, in five North American Fetal Treatment Network (NAFTNet) centers.

METHODS

This was a secondary analysis of data collected prospectively at five NAFTNet centers, conducted from January 2013 to March 2020. Inclusion criteria were a monochorionic diamniotic twin pregnancy complicated by TTTS, undergoing FLP, with preoperative CL < 30 mm. Management options for a short cervix included expectant management, vaginal progesterone, pessary (Arabin, incontinence or Bioteque cup), cervical cerclage or a combination of two or more treatments. Patients were not included if the intervention was initiated solely on the basis of having a twin gestation rather than at the diagnosis of a short cervix. Demographics, ultrasound characteristics, operative data and outcomes were compared. The primary outcome was FLP-to-delivery interval. Propensity-score matching was performed, with each treatment group matched (1:1) to the expectant-management group for CL, in order to estimate the effect of each treatment on the FLP-to-delivery interval.

RESULTS

A total of 255 women with a twin pregnancy complicated by TTTS and a short cervix undergoing FLP were included in the study. Of these, 151 (59%) were managed expectantly, 32 (13%) had vaginal progesterone only, 21 (8%) had pessary only, 21 (8%) had cervical cerclage only and 30 (12%) had a combination of treatments. A greater proportion of patients in the combined-treatment group had had a prior preterm birth compared with those in the expectant-management group (33% vs 9%; P = 0.01). Mean preoperative CL was shorter in the pessary, cervical-cerclage and combined-treatment groups (14-16 mm) than in the expectant-management and vaginal-progesterone groups (22 mm for both) (P < 0.001). There was no significant difference in FLP-to-delivery interval between the groups, nor in gestational age at delivery or the rate of live birth or neonatal survival. Vaginal progesterone was associated with a decrease in the risk of delivery before 28 weeks' gestation compared with cervical cerclage and combined treatment (P = 0.03). Using propensity-score matching for CL, cervical cerclage was associated with a reduction in FLP-to-delivery interval of 13 days, as compared with expectant management.

CONCLUSIONS

A large proportion of pregnancies with TTTS and a short maternal cervix undergoing FLP were managed expectantly for a short cervix, establishing a high (62%) risk of delivery before 32 weeks in this condition. No treatment that significantly improved outcome was identified; however, there were significant differences in potential confounders and there were also likely to be unmeasured confounders. Cervical cerclage should not be offered as a secondary prevention for preterm birth in twin pregnancies with TTTS and a short cervix undergoing FLP. A large randomized controlled trial is urgently needed to determine the effects of treatments for the prevention of preterm birth in these pregnancies. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Repopulation of decellularised porcine pulmonary valves in the right ventricular outflow tract of sheep: Role of macrophages

The primary objective was to evaluate performance of low concentration SDS decellularised porcine pulmonary roots in the right ventricular outflow tract of juvenile sheep. Secondary objectives were to explore the cellular population of the roots over time. Animals were monitored by echocardiography and roots explanted at 1, 3, 6 (n = 4) and 12 months (n = 8) for gross analysis. Explanted roots were subject to histological, immunohistochemical and quantitative calcium analysis (n = 4 at 1, 3 and 12 months) and determination of material properties (n = 4; 12 months). Cryopreserved ovine pulmonary root allografts (n = 4) implanted for 12 months, and non-implanted cellular ovine roots were analysed for comparative purposes. Decellularised porcine pulmonary roots functioned well and were in very good condition with soft, thin and pliable leaflets. Morphometric analysis showed cellular population by 1 month. However, by 12 months the total number of cells was less than 50% of the total cells in non-implanted native ovine roots. Repopulation of the decellularised porcine tissues with stromal (α-SMA+; vimentin+) and progenitor cells (CD34+; CD271+) appeared to be orchestrated by macrophages (MAC 387+/ CD163low and CD163+/MAC 387-). The calcium content of the decellularised porcine pulmonary root tissues increased over the 12-month period but remained low (except suture points) at 401 ppm (wet weight) or below. The material properties of the decellularised porcine pulmonary root wall were unchanged compared to pre-implantation. There were some changes in the leaflets but importantly, the porcine tissues did not become stiffer. The decellularised porcine pulmonary roots showed good functional performance in vivo and were repopulated with ovine cells of the appropriate phenotype in a process orchestrated by M2 macrophages, highlighting the importance of these cells in the constructive tissue remodelling of cardiac root tissues.

Virus filtration: A Review of Current and Future Practices in Bioprocessing

For drug products manufactured in mammalian cells, safety assurance practices are needed during production to assure that the final medicinal product is safe from the potential risk of viral contamination. Virus filters provide viral retention for a range of viruses through robust, largely size-based retention mechanism. Therefore, a virus filtration step is commonly utilized in a well-designed recombinant therapeutic protein purification process and is a key component in an overall strategy to minimize the risks of adventitious and endogenous viral particles during the manufacturing of biotechnology products. This review summarizes the history of virus filtration, currently available virus filters and prefilters, and virus filtration integrity test methods and study models. There is also discussion of current understanding and gaps with an eye toward future trends and emerging filtration technologies. This article is protected by copyright. All rights reserved.

Integration and functional performance of a decellularised porcine superflexor tendon graft in an ovine model of anterior cruciate ligament reconstruction

The objective was to evaluate the performance of decellularised porcine superflexor tendon (pSFT) as an anterior cruciate ligament (ACL) reconstruction device. The ACL of adult sheep was reconstructed with decellularised pSFT or ovine allograft SFT and animals sacrificed at 4, 12 and 26 weeks (n = 4 per group) for biological evaluation and 26 weeks (n = 6) for biomechanical evaluation of the grafts. Both grafts showed good in vivo performance with no major differences at macroscopic evaluation post euthanasia. Histopathology revealed an inflammatory reaction to both grafts at 4 weeks, which reduced by 26 weeks. There was advanced cellular ingrowth from 12 weeks, ligamentisation of intra-articular grafts, ossification and formation of Sharpey's fibers at the graft/bone junctions. Immunohistochemistry showed that at 4 and 12 weeks, the host response was dominated by CD163+ M2 macrophages and a cell infiltrate comprising α-SMA + myofibroblasts, CD34⁺ and CD271+ progenitor cells. At 26 weeks the biomechanical properties of decellularised pSFT and oSFT grafts were comparable, with all grafts failing in the intra-articular region. This study provides new insight into constructive remodelling of tendons used for ACL replacement and evidence of integration and functional performance of a decellularised xenogeneic tendon with potential as an alternative for ACL reconstruction.

Translation of mechanical strain to a scalable biomanufacturing process for acellular matrix production from full thickness porcine bladders

Bladder acellular matrix has promising applications in urological and other reconstructive surgery as it represents a naturally compliant, non-immunogenic and highly tissue-integrative material. As the bladder fills and distends, the loosely-coiled bundles of collagen fibres in the wall become extended and orientate parallel to the lumen, resulting in a physical thinning of the muscular wall. This accommodating property can be exploited to achieve complete decellularisation of the full-thickness bladder wall by immersing the distended bladder through a series of hypotonic buffers, detergents and nucleases, but the process is empirical, idiosyncratic and does not lend itself to manufacturing scale up. In this study we have taken a mechanical engineering approach to determine the relationship between porcine bladder size and capacity, to define the biaxial deformation state of the tissue during decellularisation and to apply these principles to the design and testing of a scalable novel laser-printed flat-bed apparatus in order to achieve reproducible and full-thickness bladder tissue decellularisation. We demonstrate how the procedure can be applied reproducibly to fresh, frozen or twice-frozen bladders to render8×8 cm²patches of DNA-free acellular matrix suitable for surgical applications.

1515 A Survey on The Perceived Effect of Background Music on Intra-Operative Stress, Anxiety and Surgical Task Load On the Operating Surgeon

Introduction

Music is commonly played in operating theatres throughout the world though its use remains controversial. There is growing literature supporting the notion that playing background music can improve a surgeon’s task performance and reduce performance stress. We present findings from our survey of surgeons about their perceptions of the effect of intra-operative music on their stress levels.

Method

Surgeons and registrars from three different specialties – general, vascular, and paediatric surgery – in a single tertiary centre were surveyed on their views on the effect of music in theatre. Two instruments were used to assess parameters of stress: the modified 6-point state trait anxiety inventory (STAI-6) and the surgical task load index (SURG-TLX).

Results

There were 35 respondents across the three surgical specialties (78% response rate). Pop and “easy listening” were the most popular genres. A majority felt music improved their temperament (75%) and perceived stress (63%). 59% of respondents reported no to low perceived anxiety with music, compared with 31% reporting moderate and 9% high anxiety based on STAI-6 parameters. Regarding SURG-TLX parameters and music, respondents overall perceived feeling less anxious, rushed and mentally fatigued though more distracted.

Conclusions

Music is generally thought to have positive subjective effects on the theatre environment with regards to anxiety levels, temperament, perceived stress, and parameters within the surgical task load index. This is counterbalanced by a smaller group of respondents who felt that music can impair communication and increase distraction within theatre. Music used appropriately may reduce perceptions of stress in theatre.

ACE inhibitors, angiotensin receptor blockers and endothelial injury in COVID-19

BACKGROUND

COVID-19 is caused by the coronavirus SARS-CoV-2, which uses angiotensin-converting enzyme 2 (ACE-2) as a receptor for cellular entry. It is theorized that ACE inhibitors (ACE-Is) or angiotensin receptor blockers (ARBs) may increase vulnerability to SARS-CoV-2 by upregulating ACE-2 expression, but ACE-I/ARB discontinuation is associated with clinical deterioration.

OBJECTIVE

To determine whether ACE-I and ARB use is associated with acute kidney injury (AKI), macrovascular thrombosis and in-hospital mortality.

METHODS

A retrospective, single-centre study of 558 hospital inpatients with confirmed COVID-19 admitted from 1 March to 30 April 2020, followed up until 24 May 2020. AKI and macrovascular thrombosis were primary end-points, and in-hospital mortality was a secondary end-point.

RESULTS

AKI occurred in 126 (23.1%) patients, 34 (6.1%) developed macrovascular thrombi, and 200 (35.9%) died. Overlap propensity score-weighted analysis showed no significant effect of ACE-I/ARB use on the risk of occurrence of the specified end-points. On exploratory analysis, severe chronic kidney disease (CKD) increases odds of macrovascular thrombi (OR: 8.237, 95% CI: 1.689-40.181, P = 0.009). The risk of AKI increased with advancing age (OR: 1.028, 95% CI: 1.011-1.044, P = 0.001) and diabetes (OR: 1.675, 95% CI: 1.065-2.633, P = 0.025). Immunosuppression was associated with lower risk of AKI (OR: 0.160, 95% CI: 0.029-0.886, P = 0.036). Advancing age, dependence on care, male gender and eGFR < 60 mL min^-1 /1.73 m² increased odds of in-hospital mortality.

CONCLUSION

We did not identify an association between ACE-I/ARB use and AKI, macrovascular thrombi or mortality. This supports the recommendations of the European and American Societies of Cardiology that ACE-Is and ARBs should not be discontinued during the COVID-19 pandemic.

An experimental simulation model to assess wear of the porcine patellofemoral joint

A range of surgical techniques and osteochondral interventions have been developed for early stage chondral/osteochondral repair interventions in the knee however, methods for functional, pre-clinical assessment of these therapies are limited. In this study, a method for simulating physiological loading and motion in the porcine patellofemoral joint was developed using a 6-axis simulator. As an example of how the method can be used, the influence of surgical positioning of osteochondral allografts in the patella on cartilage wear, deformation and damage and graft stability was investigated in this porcine patellofemoral joint model. The functional performance of allografts implanted either optimally (flush with the cartilage surface) or 1 mm proud of the cartilage surface was compared to a positive control (stainless steel pin implanted 1 mm proud of the cartilage surface), a negative control (no intervention) and a defect model. Allografts implanted flush with the surrounding cartilage could restore the articulating surface of the patella resulting in low wear, damage and deformation of the opposing cartilage surface, similar to that of the negative control group. Implanting the graft proud of the patella surface resulted in cartilage lesions on the femoral trochlea (ICRS grade 2) and a cartilage volume difference of 2.0 ± 3.9 mm3; the positive controls resulted in more severe lesions, a higher volume difference (14.2 ± 7.4 mm3) which in some cases exposed subchondral bone (ICRS grade 4). Defects in the patella caused deformation of the opposing cartilage surface. All grafts implanted in the patella subsided over the duration of the study. This study demonstrated a method that can be used to evaluate osteochondral repair strategies in the patellofemoral joint applying physiological loading and motions.

163 Frailty, Doesn’t That Mean Birdlike? Research Into Attitudes and Understanding of Frailty in Undergraduate and Postgraduate Trainees

Introduction

Frailty is an increasingly recognised concept, with 25–50% of over 85’s estimated to be frail1,. Previous research considered medical students’ attitudes towards older people2, yet despite the correlation between frailty and increased age3, little is known about attitudes of healthcare professionals towards frailty.

We researched attitudes towards, and understanding of, frailty in undergraduate and postgraduate trainees, with a view to guiding future educational interventions.

Method

Approval was granted by Northumbria Healthcare NHS Foundation Trust (NHCT) Research and Development department, Newcastle University’s Research Management Group and the HRA.

3 cohorts were recruited; 3rd year Newcastle University MBBS Students, 5th year Newcastle University MBBS Students and Foundation Year 2 and Core Medical Trainees working for NHCT (junior doctors). Data was collected during scheduled teaching at NHCT and individuals were invited to participate via email prior to this. Those not participating were still required to attend the teaching. Participants provided written consent.

Within each cohort, small group discussions around frailty and Comprehensive Geriatric Assessment (CGA) were prompted using open questions (e.g. “what does frailty mean to you?”), during which participants anonymously submitted phrases to an online word-cloud generator. Discussions were audio recorded and transcribed.

Transcriptions and word-clouds were analysed using Simple Content Analysis. The over-arching themes within each cohort were identified and compared with other cohorts. Interpretations were reviewed by an independent researcher to enhance rigour.

Results

Each cohort associated frailty with older age and weakness, and often used it as a byword for complexity. Frailty was described as an abstract construct composed of personal experiences rather than an objectively defined descriptor. All associated it with negative emotions.

Cohorts differed in their approach, with 3rd year students primarily focussed on defining frailty, whereas junior doctors prioritised the clinical challenges it presented.

Junior doctors demonstrated limited understanding of CGA whilst undergraduate students were almost universally ignorant of it.

Conclusions

The lack of understanding around frailty and CGA is concerning given its high prevalence. The identification of negative emotions increases this concern. To challenge this, focussed educational interventions addressing understanding and attitudes ought to be developed for tomorrow’s doctors.

References

1. Clegg et al. Lancet 2013; 381: 752–62.

2. Samra et al. Age Ageing 2017; 46: 911–9.

3. Romero-Ortuno et al. Age Ageing 2012; 41: 684–9.

Validation of the National Institute of Neurological Disorders and Stroke Spinal Cord Injury MRI Common Data Elements Instrument

BACKGROUND AND PURPOSE

The National Institute of Neurological Disorders and Stroke common data elements initiative was created to provide a consistent method for recording and reporting observations related to neurologic diseases in clinical trials. The purpose of this study is to validate the subset of common data elements related to MR imaging evaluation of acute spinal cord injury.

MATERIALS AND METHODS

Thirty-five cervical and thoracic MR imaging studies of patients with acute spinal cord injury were evaluated independently in 2 rounds by 5 expert reviewers. Intra- and interrater agreement were calculated for 17 distinct MR imaging observations related to spinal cord injury. These included ordinal, categoric, and continuous measures related to the length and location of spinal cord hemorrhage and edema as well as spinal canal and cord measurements. Level of agreement was calculated using the interclass correlation coefficient and kappa.

RESULTS

The ordinal common data elements spinal cord injury elements for lesion center and rostral or caudal extent of edema or hemorrhage demonstrated agreement ranging from interclass correlation coefficient 0.68 to 0.99. Reproducibility ranged from 0.95 to 1.00. Moderate agreement was observed for absolute length of hemorrhage and edema (0.54 to 0.60) with good reproducibility (0.78 to 0.83). Agreement for the Brain and Spinal Injury Center score showed the lowest interrater agreement with an overall kappa of 0.27 (0.20, 0.34). For 7 of the 8 variables related to spinal cord injury, agreement improved between the first and second evaluation. Continuous diameter measures of the spinal cord and spinal canal using interclass correlation coefficient varied substantially (0.23 to 0.83).

CONCLUSIONS

Agreement was more consistent for the ordinal measures of spinal cord injury than continuous measures. Good to excellent agreement on length and location of spinal cord hemorrhage and edema can be achieved with ordinal measures alone.

Antiviral Activity of Reagents in Mouth Rinses against SARS-CoV-2

The oral cavity, an essential part of the upper aerodigestive tract, is believed to play an important role in the pathogenicity and transmission of SARS-CoV-2. The identification of targeted antiviral mouth rinses to reduce salivary viral load would contribute to reducing the COVID-19 pandemic. While awaiting the results of significant clinical studies, which to date do not exist, the commercial availability of mouth rinses leads us to search among them for reagents that would have specific antiviral properties with respect to SARS-CoV-2. The challenges facing this target were examined for 7 reagents found in commercially available mouth rinses and listed on the ClinicalTrials.gov website: povidone-iodine, chlorhexidine, hydrogen peroxide, cyclodextrin, Citrox, cetylpyridinium chloride, and essential oils. Because SARS-CoV-2 is an enveloped virus, many reagents target the outer lipid membrane. Moreover, some of them can act on the capsid by denaturing proteins. Until now, there has been no scientific evidence to recommend mouth rinses with an anti-SARS-CoV-2 effect to control the viral load in the oral cavity. This critical review indicates that current knowledge of these reagents would likely improve trends in salivary viral load status. This finding is a strong sign to encourage clinical research for which quality protocols are already available in the literature.

Development of a specimen-specific in vitro pre-clinical simulation model of the human cadaveric knee with appropriate soft tissue constraints

A human cadaveric specimen-specific knee model with appropriate soft tissue constraints was developed to appropriately simulate the biomechanical environment in the human knee, in order to pre-clinically evaluate the biomechanical and tribological performance of soft tissue interventions. Four human cadaveric knees were studied in a natural knee simulator under force control conditions in the anterior posterior (AP) and tibial rotation (TR) axes, using virtual springs to replicate the function of soft tissues. The most appropriate spring constraints for each knee were determined by comparing the kinematic outputs in terms of AP displacement and TR angle of the human knee with all the soft tissues intact, to the same knee with all the soft tissues resected and replaced with virtual spring constraints (spring rate and free length/degree). The virtual spring conditions that showed the least difference in the AP displacement and TR angle outputs compared to the intact knee were considered to be the most appropriate spring conditions for each knee. The resulting AP displacement and TR angle profiles under the appropriate virtual spring conditions all showed similar shapes to the individual intact knee for each donor. This indicated that the application of the combination of virtual AP and TR springs with appropriate free lengths/degrees was successful in simulating the natural human knee soft tissue function. Each human knee joint had different kinematics as a result of variations in anatomy and soft tissue laxity. The most appropriate AP spring rate for the four human knees varied from 20 to 55 N/mm and the TR spring rate varied from 0.3 to 1.0 Nm/°. Consequently, the most appropriate spring condition for each knee was unique and required specific combinations of spring rate and free length/degree in each of the two axes.

The Influence of Printing Parameters and Cell Density on Bioink Printing Outcomes

Bioink printability persists as a limiting factor toward many bioprinting applications. Printing parameter selection is largely user-dependent, and the effect of cell density on printability has not been thoroughly investigated. Recently, methods have been developed to give greater insight into printing outcomes. This study aims to further advance those methods and apply them to study the effect of printing parameters (feedrate and flowrate) and cell density on printability. Two printed structures, a crosshatch and five-layer tube, were established as printing standards and utilized to determine the printing outcomes. Acellular bioinks were printed using a testing matrix of feedrates of 37.5, 75, 150, 300, and 600 mm/min and flowrates of 21, 42, 84, 168, and 336 mm³/min. Structures were also printed with cell densities of 5, 10, 20, and 40 × 10⁶ cell/mL at 150 mm/min and 84 mm³/min. Only speed ratios (defined as flowrate divided by feedrate) from 0.07 to 2.24 mm² were suitable for analysis. Increasing speed ratio dramatically increased the height, width, and wall thickness of tubular structures, but did not influence radial accuracy. For crosshatch structures, the area of pores and the frequency of broken filaments were decreased without impacting pore shape (Pr). Within speed ratios, feedrate and flowrate had negligible, inconsistent effects. Cell density did not affect any printing outcomes despite slight rheological changes. Printing outcomes were dominated by the speed ratio, with feedrate, flowrate, and cell density having little impact on printing outcomes when controlling for speed ratio within the ranges tested. The relevance of these results to other bioinks and printing conditions requires continued investigation by the bioprinting community, as well as highlight speed ratio as a key variable to report and suggest that rheology is a more sensitive measure than printing outcomes.

Sustained delivery of vascular endothelial growth factor from mesoporous calcium-deficient hydroxyapatite microparticles promotes in vitro angiogenesis and osteogenesis

Promoting the growth of blood vessels within engineered tissues remains one of the main challenge in bone tissue engineering. One way to improve angiogenesis is the use of vascular endothelial growth factor (VEGF) as it holds the ability to increase the formation of a vascular network. In the present study, collagen scaffolds with VEGF-releasing hydroxyapatite particles were fabricated, in order to engineer a material both capable of presenting an osteoconductive surface and delivering an angiogenic growth factor in a localized and sustained manner, in order to enhance osteogenesis as well as angiogenesis. To this end, we developed microparticles and characterize their size, chemical properties and Ca/P ratio to validate the formation of hydroxyapatite. We then evaluated the osteogenic potential of HAp when cultured with mesenchymal stem cells and compare it to commercially available hydroxyapatite (SBp). Finally, we characterized the encapsulation and release of VEGF in the HAp and assess the angiogenic potential of the VEGF-HAp when cultured with endothelial cells. We demonstrated the successful fabrication of calcium deficient hydroxyapatite microparticles (CDHAp), with biological properties closer to the bone than stoichiometric, commercially available hydroxyapatite. This CDHAp exhibited a well-defined 3D network of crystalline nanoplates forming mesoporous and hollow structures. The high specific area created by those structures enabled the loading of VEGF with high efficiency when compared to the loading efficiency of SBp. Furthermore, their biological performances were evaluated in vitro. Our results indicate that VEGF-CDHAp can be used to improve both osteogenesis and angiogenesis in vitro.

Parents' experiences of care following the loss of a baby at the margins between miscarriage, stillbirth and neonatal death: a UK qualitative study

OBJECTIVE

To explore the healthcare experiences of parents whose baby died either before, during or shortly after birth between 20⁺⁰ and 23⁺⁶  weeks of gestation in order to identify practical ways to improve healthcare provision.

DESIGN

Qualitative interview study.

SETTING

England through two parent support organisations and four NHS Trusts.

SAMPLE

A purposive sample of parents.

METHODS

Thematic analysis of semi-structured in-depth narrative interviews.

MAIN OUTCOME MEASURES

Parents' healthcare experiences.

RESULTS

The key overarching theme to emerge from interviews with 38 parents was the importance of the terminology used to refer to the death of their baby. Parents who were told they were 'losing a baby' rather than 'having a miscarriage' were more prepared for the realities of labour, the birth experience and for making decisions around seeing and holding their baby. Appropriate terminology validated their loss, and impacted on parents' health and wellbeing immediately following bereavement and in the longer term.

CONCLUSION

For parents experiencing the death of their baby at the margins between miscarriage, stillbirth and neonatal death, ensuring the use of appropriate terminology that reflects parents' preferences is vital. This helps to validate their loss and prepare them for the experiences of labour and birth. Reflecting parents' language preferences combined with compassionate bereavement care is likely to have a positive impact on parents' experiences and improve longer-term outcomes.

TWEETABLE ABSTRACT

Describing baby loss shortly before 24 weeks of gestation as a 'miscarriage' does not prepare parents for labour and birth, seeing their baby and making memories.

Assessment methodologies for extrusion-based bioink printability

Extrusion-based bioprinting is one of the leading manufacturing techniques for tissue engineering and regenerative medicine. Its primary limitation is the lack of materials, known as bioinks, which are suitable for the bioprinting process. The degree to which a bioink is suitable for bioprinting has been described as its 'printability.' However, a lack of clarity surrounding the methodologies used to evaluate a bioink's printability, as well as the usage of the term itself, have hindered the field. This article presents a review of measures used to assess the printability of extrusion-based bioinks in an attempt to assist researchers during the bioink development process. Many different aspects of printability exist and many different measurements have been proposed as a consequence. Researchers often do not evaluate a new bioink's printability at all, while others simply do so qualitatively. Several quantitative measures have been presented for the extrudability, shape fidelity, and printing accuracy of bioinks. Different measures have been developed even within these aspects, each testing the bioink in a slightly different way. Additionally, other relevant measures which had little or no examples of quantifiable methods are also to be considered. Looking forward, further work is needed to improve upon current assessment methodologies, to move towards a more comprehensive view of printability, and to standardize these printability measurements between researchers. Better assessment techniques will naturally lead to a better understanding of the underlying mechanisms which affect printability and better comparisons between bioinks. This in turn will help improve upon the bioink development process and the bioinks available for use in bioprinting.

102 Process Evaluation Exploring the Delivery and Uptake of Posture and Mobility Training for Staff in Care Homes

Introduction

Provision of care for care home residents with complex needs is challenging. Physiotherapists can play a major role in enhancing the confidence, skills and abilities of care home staff. The Skilful Care Training Package (SCTP) aims to provide staff with an understanding of good posture and training in skilled facilitation of movement. This process evaluation explored barriers and facilitators to delivery and uptake of the SCTP within the context of a feasibility cluster randomised controlled trial (cRCT) in 10 care homes.

Methods

A mixed methods process evaluation, incorporating non-participant observations and interviews, conducted in the five care homes receiving the SCTP intervention. Interviews were audio recorded and transcribed verbatim; resident conversations were captured via a Dictaphone and/or field-notes. Data analysis used the Framework approach.

Results

Fourteen staff training sessions were observed. Interviews with 22 staff and four trainers, and 13 conversations with residents were completed. Five factors influenced delivery and uptake of the SCTP:Organisational factors: strategies to publicise and facilitate access to training improved attendance; a convenient training location and trainer flexibility encouraged attendance and staff engagement.Intervention delivery: a practical participatory element to the training was highly valued; adapting the training to meet the needs of the homes was well-received.Engagement and interaction: relating training to workplace and residents’ experiences engaged staff; high levels of engagement and positive interaction within the training sessions were reported; challenges relating to staff hierarchy affected training delivery in some homes.Intervention content: posture and mobility elements were seen as important; however, some repetition with prior training was highlighted.Training impact: there were indications that staff adopted SCTP techniques. Staff reported an increase in their wellbeing and confidence in movement facilitation; cascade training was reported in some homes.

Conclusions

Training was well-received, and feedback on its impact was largely positive. Practical elements were viewed favourably over classroom-based learning. Intervention content should be revised to optimise focus and avoid overlap with other training.

101 A Posture and Mobility Training Package for Care Home Staff: Results of A Cluster Randomised Controlled Feasibility Trial

Introduction

Provision of care for care home residents with complex needs is challenging. Physiotherapy and activity interventions can improve physical well-being but are often time-limited and resource intensive. A sustainable approach is to enhance the confidence, skills and abilities of care home staff. This trial assessed the feasibility of undertaking a definitive evaluation of the Skilful Care Training Package (SCTP) - a posture and mobility training programme developed by physiotherapists for care home staff.

Methods

A parallel-group, cluster randomised controlled feasibility trial was undertaken in ten care homes in Yorkshire. Five were randomised to receive SCTP, five to usual care. SCTP was delivered by specialist physiotherapists, with the intention of training all direct care staff. Following consent, data were collected from and about residents with restricted mobility (those fulfilling the eligibility criteria) at baseline, three and six months post-randomisation by blinded researchers. Outcome measurement included resident mobility, posture, pain and quality of life. The feasibility of recruitment, retention, data collection and intervention delivery was assessed.

Results

All residents (348) at participating homes were screened for eligibility. 250 were eligible and 146 took part. Follow-up was balanced between arms, with an overall loss-to-follow-up rate of 28.8% at six months. Where residents were available for six-month follow-up, proxy data provision was excellent (97.1% - 100% of expected data). Difficulty collecting data directly from residents was experienced (43.3% of expected data) due to high levels of cognitive impairment. Staff attendance at training met or was close to pre-specified criteria for acceptability in three homes, with 63.0%, 63.6% and 65.8% direct care staff attending all sessions, and &gt;85% attending at least one session across all three homes. However attendance fell short of acceptability in two homes, with only 21.4% and 12.5% staff attending all sessions.

Conclusions

It is feasible to recruit and follow-up residents in a randomised trial comparing SCTP and usual care. Proxy data collection is a successful method, but collection of data from residents is difficult. Intervention delivery success was variable, illustrating heterogeneity between care homes. Future research will be informed by learning from those homes with greater intervention compliance. Work should be undertaken to investigate how best to collect meaningful data from residents.

Biomechanical assessment of the stability of osteochondral grafts implanted in porcine and bovine femoral condyles

Osteochondral grafts are used clinically to repair cartilage and bone defects and to restore the congruent articulating surfaces of the knee joint following cartilage damage or injury. The clinical success of such osteochondral grafts is heavily reliant on the biomechanical and tribological properties of the surgical repair; however, a limited number of studies have investigated these factors. The aim of this study was to evaluate the influence of graft harvesting and implantation technique as well as bone properties on the primary stability of press-fit implanted osteochondral grafts using a series of uniaxial experimental push-in and push-out tests. Animal (porcine and bovine) knees were used to deliver models of different bone properties (elastic modulus and yield stress). The study showed the graft harvesting method using either a chisel or drill-aided trephine to have no influence on primary graft stability; however, the preparation technique for the graft recipient site was shown to influence the force required to push the graft into the host tissue. For example, when the length of the graft was equal to the recipient site (bottomed), the graft was more stable and dilation of the recipient site was shown to reduce short-term graft stability especially in immature or less dense bone tissue. The push-out tests which compared tissue of different skeletal maturities demonstrated that the maturity of both the graft and host bone tissue to influence the stability of the graft. A higher force was required to push out more skeletally mature grafts from mature bone tissue. The study demonstrates the importance of surgical technique and bone quality/properties on the primary stability and ultimately, the success of osteochondral grafts in the knee.

3D printed HUVECs/MSCs cocultures impact cellular interactions and angiogenesis depending on cell-cell distance

Vascularization is a crucial process during the growth and development of bone ¹, yet it remains one of the main challenges in the reconstruction of large bone defects. The use of in vitro coculture of human umbilical vein endothelial cells (HUVECs) and human mesenchymal stem cells (hMSCs) has been one of the most explored options. Both cell types secrete specific growth factors that are mutually beneficial, and studies suggested that cell-cell communication and paracrine secretion could be affected by a number of factors. However, little is known about the effect of cell patterning and the distance between cell populations on their crosstalk. In the present study, we showed that the separation and distance between ECs and MSCs populations affects angiogenesis by modulating cell-cell communication. HUVECs grown farther apart from MSCs (˃400 μm) presented characteristics of an early stage of angiogenesis (migration/proliferation). Results showed an increase in the up-regulation of VEGF, FGF-2, and ITGA3 (integrins) but a smaller fold change in the expression of VE-Cadherin and Ang-1. HUVECs were also still highly proliferative. On the contrary, HUVECs incubated closer (≤200 μm) to MSCs, showed signs of stabilization, mainly an increase in Ang-1 and VE-cadherin expression, as well as tighter monolayers. Conditioned media collected from HUVECs and MSCs grown ≤200 μm apart preferentially promoted tube formation, a later stage of angiogenesis, due in part to a significant increase in Ang-1 paracrine secretion. In addition, in groups in which fibers were printed farther apart (400 μm), cells produced EVs with a significantly increase cargo. Finally, in vivo experiment results showed an increase in blood vessels density and new bone thickness after 12 weeks of implantation in rat cranial defect, further suggesting the higher efficiency of indirect ECs/MSCs contact in prompting the release of paracrine signals that stimulate the angiogenesis of local tissues, and enhanced subsequent bone regeneration.

The effect of surgical alignment and soft tissue conditions on the kinematics and wear of a fixed bearing total knee replacement

As life expectancy and activity levels of patients increase so does the demand on total knee replacements (TKRs). Abnormal mechanics and wear of TKRs can lead to implant loosening and revision. Component alignment after surgery varies due to the presurgical alignment, the accuracy of the surgical instrumentation and due to patient factors, such as the soft tissue balance. This study experimentally investigated the effect of variation in component alignment and the soft tissue conditions on the kinematics and wear of a fixed bearing TKR. DePuy Sigma fixed bearing TKRs with moderately cross-linked UHMWPE were used. Different alignment conditions were simulated in the coronal, sagittal and transverse planes in an ISO force-controlled simulation system. Three different soft tissue conditions were simulated using virtual springs to represent a stiff knee, a preserved PCL and a resected PCL. Four different alignment conditions were studied; ideal alignment, 4° tibial and femoral varus joint line, 14° rotational mismatch and 10° posterior tibial slope. The varus joint line alignment resulted in similar kinematics and lower wear rate compared to ideal alignment. The rotational mismatch alignment resulted in significantly higher tibial rotation and abduction-adduction as well as a significantly higher wear rate than ideal alignment. The posterior tibial slope alignment resulted in significantly higher wear than the ideal alignment and dislocated under the lower tension soft tissue conditions. Component alignment and the soft tissue conditions had a significant effect on the kinematics and wear of the TKR investigated in this study. The surgical alignment of the TKR is an important factor in the clinical outcome of the joint as factors such as increased tibial rotation can lead to anterior knee pain and instability and increased wear can lead to aseptic loosening and early failure resulting in revision.