Aims. Body exhaust suits or surgical helmet systems (colloquially, ‘space suits’) are frequently used in many forms of arthroplasty, with the aim of providing personal protection to surgeons and, perhaps, reducing periprosthetic joint infections, although this has not consistently been borne out in systematic reviews and registry studies. To date, no large-scale study has investigated whether this is applicable to shoulder arthroplasty. We used the New Zealand Joint Registry to assess whether the use of surgical helmet systems was associated with lower all-cause revision or revision for deep infection in primary shoulder arthroplasties. Methods. We analyzed 16,000 shoulder arthroplasties (hemiarthroplasties, anatomical, and reverse geometry prostheses) recorded on the New Zealand Joint Registry from its inception in 2000 to the present day. We assessed patient factors including age, BMI, sex, and American Society of Anesthesiologists (ASA) grade, as well as whether or not the operation took place in a laminar flow operating theatre. Results. A total of 2,728 operations (17%) took place using surgical helmet systems. Patient cohorts were broadly similar in terms of indication for surgery (osteoarthritis, rheumatoid arthritis, fractures) and medical comorbidities (age and sex). There were 842 revisions (5% of cases) with just 98 for deep infection (0.6% of all cases or 11.6% of the revisions). There were no differences in all-cause revisions or revision for deep infection between the surgical helmet systems and conventional gowns (p = 0.893 and p = 0.911, respectively). Conclusion. We found no evidence that wearing a surgical helmet system reduces the incidence of periprosthetic joint infection in any kind of primary shoulder arthroplasty. We acknowledge the limitations of this registry study and accept that there may be other benefits in terms of personal protection, comfort, or visibility. However, given their financial and ecological footprint, they should be used judiciously in shoulder surgery. Cite this article: Bone Jt Open 2024;5(10):894–897

The use of exhaust suit systems is commonplace in arthroplasty surgery where isolation of the surgical team is desirable in an attempt to reduce the risk of infection transmission. Elevated carbon dioxide levels have been reported in the non-clinical setting with such systems the consequences of which can include fatigue, diaphoresis, nausea, headache and irritability. The aim of our study was to determine the levels of carbon dioxide present within an exhaust suit system during hip arthroplasty and to compare these with the recommended occupational exposure limit levels published by the Health and Safety Executive (HSE). Data was collected during ten primary hip replacements performed by the same surgeon whilst wearing the Stryker Steri-Shield Helmet Exhaust System. This is a self-contained unit with an integrated blower used in conjunction with a full-length gown. In addition the helmet was fitted with an air-sampling probe connected to a portable infrared CO. 2. monitor and also a temperature probe. Thus continuous monitoring of both CO. 2. and temperature level during surgery was possible. The mean initial CO. 2. concentration in the helmet at the beginning of surgery was 3000 parts per million (ppm) and the mean maximum CO. 2. level recorded was 13,000 ppm. The mean time the surgeon was within an exhaust suit to perform a primary hip replacement was 1 hr 54 mins and for 86% of this time period the CO. 2. level within the helmet exceeded the recommended level of 5000 ppm as stipulated by the HSE. In conclusion we have demonstrated significantly elevated CO. 2. levels within the Stryker Steri-shield Exhaust Suit System during hip surgery. Surgeons who use this system should be aware of this together with the physical symptoms that may result

The use of exhaust suit systems is commonplace in arthroplasty surgery where isolation of the surgical team is desirable in an attempt to reduce the risk of infection transmission. Elevated carbon dioxide levels have been reported in the non-clinical setting with such systems the consequences of which can include fatigue, diapho-resis, nausea, headache and irritability. The aim of our study was to determine the levels of carbon dioxide present within an exhaust suit system during hip arthroplasty and to compare these with the recommended occupational exposure limit levels published by the Health and Safety Executive (HSE). Data was collected during ten primary hip replacements performed by the same surgeon whilst wearing the Stryker Steri-Shield Helmet Exhaust System. This is a self-contained unit with an integrated blower used in conjunction with a full-length gown. In addition the helmet was fitted with an air-sampling probe connected to a portable infrared CO2 monitor and also a temperature probe. Thus continuous monitoring of both CO2 and temperature level during surgery was possible. The mean initial CO2 concentration in the helmet at the beginning of surgery was 3 000 parts per million (ppm) and the mean maximum CO2 level recorded was 13 000 ppm. The mean time the surgeon was within an exhaust suit to perform a primary hip replacement was 1 hr 54 mins and for 86% of this time period the CO2 level within the helmet exceeded the recommended level of 5 000 ppm as stipulated by the HSE. In conclusion we have demonstrated significantly elevated CO2 levels within the Stryker Steri-shield Exhaust Suit System during hip surgery. Surgeons who use this system should be aware of this together with the physical symptoms that may result

Introduction. Surgical spacesuits are in widespread use. Only one previous study (JBJS 1998) has assessed the quality of the environment within the space suit. They demonstrated that surgical spacesuits could allow re-breathing of carbon dioxide (CO. 2. ). However, they had no control group and performed a vigorous exercise protocol which may have been an unfair test. The design of helmet systems has also evolved in the last decade. We have conducted the first investigation into CO. 2. levels inside the modern space suit. There is a Workplace Exposure Limit for inspired CO. 2. as determined by the Health and Safety Executive (UK), which is 0.506kPa. We wondered whether re-breathing of CO. 2. in space suits would lead to inspired CO. 2. which breaches this level. Methods. We used an anaesthetic room gas analyzer via nasal cannulae to measure inspired (ICO. 2. ) levels in 12 healthy volunteers. Readings were taken while wearing a surgical space suit with the fan on high and low settings. These were compared with a normal surgical facemask. Readings were repeated on mild exertion to simulate the effort of performing arthroplasty surgery. Results. [Frequency of ICO2 >0.5kPa (12 subjects)]. Discussion. Despite the design modifications, modern space suits allow re-breathing of CO. 2. This is more marked with exertion and with low fan settings where ICO. 2. can exceed workplace limits. This may account for symptoms of headache and drowsiness reported after a prolonged period in the suit during arthroplasty surgery. We recommend the use of high fan settings at all times

Soon, UK surgeons will need to undergo regular revalidation and relicensing. As a part of this process they will need to collect accurate outcomes data. However, a lack of standardisation has led to numerous generic and disease specific outcome tools being available with increasing complexity in their administration and interpretation. In research and university settings these tools are easily administered, but in a busy general spinal practice with limited human and time resources, it may not be possible to use them reliably and consistently. Web-based systems remove some of these problems, but data-input can be time consuming.

This study evaluates the utility of a subjective Patient Satisfaction Evaluation Questionnaire (PSE) by comparing it to well-known outcome tools, the Oswestry disability Index (ODI) and the Low Back Outcome Score (LBOS).

The PSE (modified Odom’s Criteria) evaluates pain, the willingness to undergo surgery again in similar circumstances, the likelihood of recommending the operation undergone to a friend or family member and satisfaction with the process of care. Pain relief is ranked as “complete”, “good but not complete”, “little” or “no pain relief/pain worse than before surgery”. The responses are scored with three points allocated to complete relief of pain, down to none for no relief. The other questions score one for a positive and zero for a negative response. The maximum score is six. Four, five or six points count as success as long as the pain component is two or three. Nought to three, counts as failure, as does a score of four when pain is rated as “poor”.

The ODI, LBOS and PSE are not directly numerically comparable, but the results of them all can be grouped into “Success” and “Failure” which gives a basis for comparison of the tools.

150 consecutive patients who underwent lumbar spine surgery completed the three questionnaires independently of the treating surgeon. The scores were subjected to regression analysis (R square) and a Pearson’s correlation. Feedback was sought from the patients regarding the “user friendliness” of the questionnaires.

Results showed a good correlation between the ODI and LBOS with a Pearson’s value and R Square (RSQ) value of 0.86 and 0.75 respectively. The PSE compared to the ODI showed a Pearson’s value of 0.86 and RSQ of 0.74. The LBOS and PSE comparison had a Pearson’s value of 0.78 and RSQ of 0.61. The results show that the PSE in the form used correlates well with results from the ODI and LBOS. However, the patient feedback data indicated that the PSE was the most user friendly of the three tools.

The PSE was found to be a useful and user friendly tool, correlating well with recognised outcome measures, being easy to administer, document and interpret. If surgeons with limited resources cannot reliably use a more rigorous outcome tool, using the PSE should provide enough data to meet the standards that are likely to be required for revalidation and relicensing.

This study in UCA (ultra clean air) during TKR (total knee replacement) quantified wound bacterial counts, assessed the relationship to air counts and compared BES (body exhaust suits) with Rotecno occlusive clothing.

Fifty TKR were randomly allocated to scrub teams wearing BES or Rotecno occlusive clothing. Air bacterial counting within 30cm of a wound is the established methodology to define air cleanliness. Reliable wound bacterial counting should be a more precise index of infection risk however, to date, there is no established accurate method. The TSMI (tetrazolium stained membrane imprint) method of bacterial wound counting has been validated in a tissue model and human surgical wounds in conventionally ventilated theatres.

This method remains to be assessed in UCA where wounds may be too clean for bacteria to be detected accurately. We used air counts within 30cm of the wound and tested the TSMI method in wounds.

Bacteria were recovered from 62% of the wounds. The mean air count wearing BES was 0. 5 cfu/m3 compared with 1. 0 cfu/m3 with Rotecno. The air counts were significantly higher with Rotecno clothing (p=0. 014, Toeplitz covariance analysis). The mean wound count was 14 bacteria/ wound with BES and 8 bacteria/wound with Rotecno. Although the counts were higher with BES the difference was not significant (p=0. 7, MannWhitney U test). There was no significant correlation between air and wound counts (r = 0. 108, Spearman’s).

On first impression Rotecno occlusive clothing would appear to be less effective than BES on account of the higher air counts. However wounds were equally contaminated with both clothing types. As there is no relationship between wound and air counts, this suggests that at very low levels of air contamination the contribution of bacteria to the wound from the air is irrelevant. Even doubling of air counts from 0. 5 to 1. 0 cfu/m3 had no detectable effect on the wound.

Knee arthroscopy is typically approached from the anterior, posteromedial and posterolateral portals. Access to the posterior compartments through these portals can cause iatrogenic cartilage damage and create difficulties in viewing the structures of the posterior compartments. The purpose of this study was to assess the feasibility of needle arthroscopy using direct posterior portals as both working and visualising portals. For workability, the needle scope was inserted advanced from anterior between the cruciate ligament bundle and the lateral wall of the medial femoral condyle until the posterior compartments were visualised. For visualisation, direct postero-lateral and -medial portals were established. The technique was performed in 9 knees by two experienced researchers. Workability and instrumentation of the posteromedial compartment and meniscus was achieved in 56%. The posterior horns could not be visualised in four specimens as the straight lens could not provide a more medial field of view. Visualisation from the direct medial posterior portal allowed a clear view of the medial meniscus, femoral condyle and posterior cruciate ligament in all specimens. Workability and instrumentation of the posterolateral compartment was not possible with the needle scope. Direct posterior approaches for the posteromedial compartment access are challenging with the current needle scope options and could only be achieved in over 50%. The postero-lateral compartment was not accessible. An angled lens or a flexible Needle scope would be better suited for developing this technique further

Surgical education of fracture fixation biomechanics relies mainly on simplified illustrations to distill the essence of the underlying principles. These mostly consist of textbook drawings or hands-on exercises during courses, both with unique advantages such as broad availability and haptics, respectively. Computer simulations are suited to bridge these two approaches; however, the validity of such simulations must be guaranteed to teach the correct aspects. Therefore, the aim of this study was to validate finite element (FE) simulations of bone-plate constructs to be used in surgical education in terms of fracture gap movement and implant surface strain. The validation procedure was conducted in a systematic and hierarchical manner with increasing complexity. First, the material properties of the isolated implant components were determined via four-point bending of the plate and three-point bending of the screw. Second, stiffness of the screw-plate interface was evaluated by means of cantilever bending to determine the properties of the locking mechanism. Third, implant surface strain and fracture gap motion were measured by testing various configurations of entire fixation constructs on artificial bone (Canevasit) in axial compression. The determined properties of the materials and interfaces assessed in these experiments were then implemented into FE models of entire fixation constructs with different fracture width and screw configurations. The FE-predicted implant surface strains and fracture gap motions were compared with the experimental results. The simulated results of the different construct configurations correlated strongly with the experimentally measured fracture gap motions (R. 2. >0.99) and plate surface strains (R. 2. >0.95). In a systematic approach, FE model validation was achieved successfully in terms of fracture gap motion and implant deformation, confirming trustworthiness for surgical education. These validated models are used in a novel online education tool OSapp (. https://osapp.ch/. ) to illustrate and explain the biomechanical principles of fracture fixations in an interactive manner

Introduction. The current treatment for Freiberg's osteochondrosis centres around either: simple debridement or debridement osteotomy. The main principle of the osteotomy is to rotate normal articular cartilage into the affected area. We recommend the use of CT scanning to delineate the amount of available, unaffected cartilage available to rotate into the affected space. Methods. We retrospectively reviewed 32 CT scans of new Freiberg's diagnoses in Sheffield over a 10 year period using the PACS system. We identified the sagittal CT slice that displayed the widest portion of proximal articular margin of the proximal phalanx and measured the diseased segment of the corresponding metatarsal head as an arc (in degrees). This arc segment was divided by 360°. This gave a ratio of the affected arc in the sagittal plane. Results. 28 out of 32 cases involved the 2nd metatarsal with the remaining 4 involving the 3rd metatarsal head. Of 32 cases, 18 had fragmentation. Surgically, 20 had debridement only, 5 also had an osteotomy and 1 had a fusion. 6 of the 32 cases were managed non-operatively. 11 cases out of 32 had an arc ratio of < 0.3. Of these, only 3 had an osteotomy, 3 had no procedure and 5 had a simple debridement. Of those that had osteotomies (5/32), 3 of the 5 cases had an arc ratio of < 0.3 with the other 2 being 0.42 and 0.38. Discussion. We hypothesise that those cases with an arc ratio of less 0.3 would be amenable to a dorsal closing wedge osteotomy and those with a ratio of more than 0.4 would be better suited to a simple debridement. For those cases between 0.3–0.4, we feel either option is viable. Further work to prove or disprove outcomes related to our classification is required

The regenerative capacity of hyaline cartilage is greatly limited. To prevent the onset of osteoarthritis, cartilage defects have to be properly treated. Cartilage, tissue engineered by mean of bioactive glass (BG) scaffolds presents a promising approach. Until now, conventional BGs have been used mostly for bone regeneration, as they are able to form a hydroxyapatite (HA) layer and are therefore, less suited for cartilage reconstruction. The aim of this study is to compare two BGs based on a novel BG composition tailored specifically for cartilage (CAR12N) and patented by us with conventional BG (BG1393) with a similar topology. The highly porous scaffolds consisting of 100% BG (CAR12N, CAR12N with low Ca2+/Mg2+ and BG1393) were characterized and dynamically seeded with primary porcine articular chondrocytes (pACs) or primary human mesenchymal stem cells (hMSCs) for up to 21 days. Subsequently, cell viability, DNA and glycosaminoglycan contents, cartilage-specific gene and protein expression were evaluated. The manufacturing process led to a comparable high (over 80%) porosity in all scaffold variants. Ion release and pH profiles confirmed bioactivity for them. After both, 7 and 21 days, more than 60% of the total surfaces of all three glass scaffold variants was densely colonized by cells with a vitality rate of more than 80%. The GAG content was significantly higher in BG1393 colonized with pACs. In general, the GAG content was higher in pAC colonized scaffolds in comparison to those seeded with hMSCs. The gene expression of cartilage-specific collagen type II, aggrecan, SOX9 and FOXO1 could be detected in all scaffold variants, irrespectively whether seeded with pACs or hMSCs. Cartilage-specific ECM components could also be detected at the protein level. In conclusion, all three BGs allow the maintenance of the chondrogenic phenotype or chondrogenic differentiation of hMSCs and thus, they present a high potential for cartilage regeneration

Introduction. Articular cartilage has a low self-regeneration capacity. Cartilage defects have to be treated to minimize the risk of the onset of osteoarthritis. Bioactive glass (BG) is a promising source for cartilage tissue engineering. Until now, conventional BGs (like BG1393) have been used, mostly for bone regeneration, as they are able to form a hydroxyapatite layer and are therefore, less suited for cartilage reconstruction. The aim of this study is to study the effect of 3D printed hydrogel scaffolds supplemented with spheres of the BG CAR12N to improve the chondrogenesis of mesenchymal stem cells (MSCs). Method. Based on our new glass composition (CAR12N), small BG spheres (25-40 µm) were produced and mixed with hydrogel and primary human (h) MSCs. Grid printed scaffolds were cultivated up to 21 days in expansion or chondrogenic differentiation medium. Macroscopical images of the scaffolds were taken to observe surface changes. Vitality, DNA and sulfated glycosaminoglycan (GAG) content was semiquantitatively measured as well as extracellular matrix gene transcription. Result. It was possible to print grid shaped hydrogel scaffolds with BG spheres and hMSCs. No significant changes in scaffold shape, surface or pore size were detected after 21 days in culture. The BG spheres were homogeneously distributed inside the grids. Vitality was significantly higher in grids with CAR12N spheres in comparison to those without. The DNA content remained constant over three weeks, but was higher in the sphere containing scaffolds than in those without BG spheres. GAG content in the grids increased not only with additional cultivation time but especially in grids with BG spheres in chondrogenic medium. Aggrecan and type II collagen gene expression was significantly higher grids cultured in the chondrogenic differentiation medium. Conclusion. This developed 3D model, is very interesting to study the effect of BG on hMSCs and to understand the influence of leaking ions on chondrogenesis

Aims. Management of intra-articular calcaneal fractures remains a debated topic in orthopaedics, with operative fixation often held in reserve due to concerns regarding perioperative morbidity and potential complications. The purpose of this study was to identify the characteristics of patients who developed surgical complications to inform the future stratification of patients best suited to operative treatment for intra-articular calcaneal fractures and those in whom surgery was highly likely to produce an equivocal functional outcome with potential post-operative complications. Methods. All patients who underwent open reduction and internal fixation of calcaneal fractures utilizing the Sinus Tarsi approach between March 2014 and July 2018 were identified using theatre records. Patient imaging was used to assess pre- and post-operative fracture geometry with Computed Tomography (CT) used for pre-operative planning. Each patient's clinical presentation was established through retrospective analysis of medical records. Patients provided verbal consent to participation and patient reported outcome measures were recorded using the Maryland Foot Score. Results. Fifty-eight intra-articular calcaneal fractures (fifty-three patients including five bilateral, mean age = 46.91 years) were included. Forty-nine patients were injured as a result of a fall from a height (92.4%). Mean time from presentation to surgery was 3.23 days (range 0–21). Mean Maryland Foot score was found to be 77.6 (+/− 16.22) in forty-five patients. Five patients (9.4%) had wound complications; two superficial (3.7%) and three deep (5.6%). Conclusion. Intra-articular fractures of the calcaneus should be considered for surgical intervention in order to improve long-term functional outcomes. The Sinus Tarsi approach provides the potential to decrease the operative complication rate whilst maintaining adequate fixation, however, the decision to surgically manage these fractures should be carefully balanced against the risk of post-operative complications. This increased risk of complication associated with smoking may tip the balance against benefit from surgical management

Introduction. Reducing infection in total joint replacement by using ultra clean air and protective enclosed suits (space suits) has become the standard in many operating theatres without good supporting evidence. This study examined the impact of laminar flow and space suits on the rate of revision for early infection following total hip (THR) and knee (TKR) replacement. Method. We used the 10-year results of the New Zealand Joint Registry to compare the rates of revision for early infection between laminar flow and conventional theatres both with and without the use of space suits. We separated hospitals and surgeons who had worked with and without space suits in both environments to exclude other confounding variables. Results. There were 51,485 THR and 36,826 TKR registered with laminar flow theatres used for 50% of the procedures and space suits used in 44% of cases. In THR there was a significant increase in revision for early infection in those procedures performed with the use of a space suit (p< 0.0001), for those performed in a laminar flow theatre (p< 0.003) and those procedures performed in a laminar flow theatre with a space suit (p< 0.001). The results were similar in TKR with the use of a space suit (p< 0.001), in laminar flow theatres (p< 0.019) and when laminar flow and space suits were used (p< 0.001). The results were unchanged when the surgeons and hospitals were analysed individually. Conclusion. The rate of revision for early infection has not been reduced by using laminar flow and space suits. The results of this study question the rationale for the increasing use and cost to the health system of these modalities in routine joint replacement

Abstract. OBJECTIVES. Application of deep learning approaches to marker trajectories and ground reaction forces (mocap data), is often hampered by small datasets. Enlarging dataset size is possible using some simple numerical approaches, although these may not be suited to preserving the physiological relevance of mocap data. We propose augmenting mocap data using a deep learning architecture called “generative adversarial networks” (GANs). We demonstrate appropriate use of GANs can capture variations of walking patterns due to subject- and task-specific conditions (mass, leg length, age, gender and walking speed), which significantly affect walking kinematics and kinetics, resulting in augmented datasets amenable to deep learning analysis approaches. METHODS. A publicly available (. https://www.nature.com/articles/s41597-019-0124-4. ) gait dataset (733 trials, 21 women and 25 men, 37.2 ± 13.0 years, 1.74 ± 0.09 m, 72.0 ± 11.4 kg, walking speeds ranging from 0.18 m/s to 2.04 m/s) was used as the experimental dataset. The GAN comprised three neural networks: an encoder, a decoder, and a discriminator. The encoder compressed experimental data into a fixed-length vector, while the decoder transformed the encoder's output vector and a condition vector (containing information about the subject and trial) into mocap data. The discriminator distinguished between the encoded experimental data from randomly sampled vectors of the same size. By training these networks jointly using the experimental dataset, the generator (decoder) could generate synthetic data respecting specified conditions from randomly sampled vectors. Synthetic mocap data and lower limb joint angles were generated and compared to the experimental data, by identifying the statistically significant differences across the gait cycle for a randomly selected subset of the experimental data from 5 female subjects (73 trials, aged 26–40, weighing 57–74 kg, with leg lengths between 868–931 mm, and walking speeds ranging from 0.81–1.68 m/s). By conducting these comparisons for this subset, we aimed to assess the synthetic data generated using multiple conditions. RESULTS. We visually inspected the synthetic trials to ensure that they appeared realistic. The statistical comparison revealed that, on average, only 2.5% of the gait cycle showed significantly differences in the joint angles of the two data groups. Additionally, the synthetic ground reaction forces deviated from the experimental data distribution for an average of 2.9% of the gait cycle. CONCLUSIONS. We introduced a novel approach for generating synthetic mocap data of human walking based on the conditions that influence walking patterns. The synthetic data closely followed the trends observed in the experimental data, also in the literature, suggesting that our approach can augment mocap datasets considering multiple conditions, an approach unfeasible in previous work. Creation of large, augmented datasets allows the application of other deep learning approaches, with the potential to generate realistic mocap data from limited and non-lab-based data. Our method could also enhance data sharing since synthetic data does not raise ethical concerns. You can generate and download virtual gait data using our GAN approach from . https://thisgaitdoesnotexist.streamlit.app/. . Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Aim. The coronavirus disease 2019 (COVID-19) pandemic presents significant challenges to healthcare systems globally. Orthopaedic surgeons are at risk of contracting COVID-19 due to their close contact with patients in both outpatient and theatre environments. The aim of this review was to perform a literature review, including articles of other coronaviruses, to formulate guidelines for orthopaedic healthcare staff. Methods. A search of Medline, EMBASE, the Cochrane Library, World Health Organization (WHO), and Centers for Disease Control and Prevention (CDC) databases was performed encompassing a variety of terms including ‘coronavirus’, ‘covid-19’, ‘orthopaedic’, ‘personal protective environment’ and ‘PPE’. Online database searches identified 354 articles. Articles were included if they studied any of the other coronaviruses or if the basic science could potentially applied to COVID-19 (i.e. use of an inactivated virus with a similar diameter to COVID-19). Two reviewers independently identified and screened articles based on the titles and abstracts. 274 were subsequently excluded, with 80 full-text articles retrieved and assessed for eligibility. Of these, 66 were excluded as they compared personal protection equipment to no personal protection equipment or referred to prevention measures in the context of bacterial infections. Results. There is a paucity of high quality evidence surrounding COVID-19. This review collates evidence from previous coronavirus outbreaks to put forward recommendations for orthopaedic surgeons during the COVID-19 pandemic. The key findings have been summarized and interpreted for application to the orthopaedic operative setting. Conclusion. For COVID-19 positive patients, minimum suggested PPE includes N95 respirator, goggles, face shield, gown, double gloves, and surgical balaclava. Space suits not advised. Be trained in the correct technique of donning and doffing PPE. Use negative pressure theatres if available. Minimize aerosolization and its effects (smoke evacuation and no pulse lavage). Minimize further unnecessary patient-staff contact (dissolvable sutures, clear dressings, split casts)

Introduction. The aim of this study was to assess patients and healthcare professionals (HCPs) opinions on the validity of using a biopsychosocial model rather than a biomedical model in alleviating patient symptoms/pain. Method. We constructed a questionnaire to assess beliefs on the effectiveness of using a biopsychosocial or biomedical model to develop a treatment plan to optimise patient symptoms/pain. We distributed the questionnaire to new and follow-up patients and healthcare professional in the orthopaedic department. Results. 246 questionnaires were completed - 183 patients and 63 HCPs. The patient group consisted of 77 males and 106 females, the HCP group of 27 males and 36 females. 77(42%) of patients and 9(14%) of HCPs agree the biomedical model is best suited to treat symptoms. 81(44%) of patients and 62(98%) of HCPs agree the biopsychosocial model is best suited to treat symptoms. 70(38%) of patients and 61 (97%) of HCPs agree stress can increase pain. 87(48%) of patients and 62(98%) of HCPs agree distress can increase pain. 83(45%) of patients and 56(89%) of HCPs agree stress can increase disability. 81(44%) of patients and 56(89%) of HCPs agree distress can increase disability. 39(21%) of patients and 43(68%) of HCPs agree if all investigations show no abnormality in explaining symptoms, the main contributor is stress, distress or psychological/socioeconomic factor. Conclusion. HCPs recognise the biopsychosocial model as a useful tool in managing patients pain/symptoms which not recognised by patients. HCPs believe that stress, distress, psychological/socioeconomic factors have a significant impact on a patients pain and disability when compared to patients. No conflicts of interest. No funding obtained

Abstract. Focal articular cartilage defects do not heal and, left untreated, progress to more widespread degenerative changes. A promising new approach for the repair of articular cartilage defects is the application of cell-based regenerative therapies using mesenchymal stromal cells (MSCs). MSCs are however present in a number of tissues and studies suggest that they vary in their proliferation, cell surface characterisation and differentiation. As the phenotypic properties of MSCs vary depending on tissue source, a systematic comparison of the transcriptomic signature would allow a better understanding of these differences between tissues, and allow the identification of markers specific to a MSC source that is best suited for clinical application. Tissue was used from patients undergoing total knee replacement surgery for osteoarthritis following ethical approval and informed consent. MSCs were isolated from bone, cartilage, synovium and infrapatellar fat pad. MSC number and expansion were quantified. Following expansion in culture, MSCs were characterised using flow cytometry with several cell surface markers; the cells from all sources were positive for CD44, CD90 and CD105. Their differentiation potential was assessed through tri-lineage differentiation assays. In addition, bulk mRNA-sequencing was used to determine the transcriptomic signatures. Differentially expressed (DE) genes were predicted. An enrichment analysis focused on the DE genes, against GO and pathway databases (KEGG and Reactome) was performed; protein-protein interaction networks were also inferred (Metascape, Reactome, Cytoscape). Optimal sourcing of MSCs will amplify their cartilage regeneration potential. This is imperative for assessing future therapeutic transplantation to maximise the chance of successful cartilage repair. A better understanding of differences in MSCs from various sources has implications beyond cartilage repair

Using an institutional database we have identified over 1000 femoral revisions using extensively porous-coated stems. Using femoral re-revision for any reason as an endpoint, the survivorship is 99 ± 0.8% (95% confidence interval) at 2 years, 97 ± 1.3% at 5 years, 95.6 ± 1.8% at 10 years, and 94.5 ± 2.2% at 15 years. Similar to Moreland and Paprosky, we have identified pre-revision bone stock as a factor affecting femoral fixation. When the cortical damage involved bone more than 10cm below the lesser trochanter, the survivorship, using femoral re-revision for any reason or definite radiographic loosening as an endpoint, was reduced significantly, as compared with femoral revisions with less cortical damage. In addition to patients with Paprosky Type 3B and 4 femoral defects, there are rare patients with femoral canals smaller than 13.5mm or larger than 26mm that are not well suited to this technique. Eight and 10 inch stems 13.5 or smaller should be used with caution if there is no proximal bone support for fear of breaking. Patients with canals larger than 18mm may be better suited for a titanium tapered stem with flutes. While a monolithic stem is slightly more difficult for a surgeon to insert than a modular femoral stem there is little worry about taper junction failure

Introduction and Objective. Local cartilage defects in the knee are painful and mostly followed by arthritis. In order to avoid impaired mobility, the osteochondral defect might be bridged by a synthetic compound material: An osteoconductive titanium foam as an anchoring material in the subchondral bone and an infiltrated polymer as gliding material in contact with the surrounding natural cartilage. Materials and Methods. Titanium foam cylinders (Ø38 mm) with porosities ranging from 57% to 77% were produced by powder metallurgy with two different grain sizes of the space holder (fine: 340 ± 110 μm, coarse: 530 ± 160 μm). The sintered titanium foam cylinders were infiltrated with UHMWPE powder on one end and UHMWPE bulk at the other end, at two different temperatures (160 °C, 200 °C), using a pressure of 20 MPa for 15 minutes. Smaller cylinders (Ø16 mm) were retrieved from the compound material by water jet cutting. The infiltration depths were determined by optical microscopy. The anchoring of the UHMWPE was measured by a shear test and the mechanical properties of the titanium foam were verified by a subsequent compression test. The tribological behaviour was investigated in protein containing liquid using fresh cartilage pins (Ø5 mm) sliding against a UHMWPE disc with or without a notch to simulate the gap between the implant and the surrounding cartilage. Friction coefficients were determined in a rotation tribometer and the cartilage wear in a multidirectional six-station tribometer from AMTI (load 10 – 50 N, sliding speed 20 mm/s, 37 °C). Results. UHMWPE could be infiltrated into titanium foam by 1.1 – 1.3 mm with fine pores and by 1.5 – 1.8 mm with coarse pores. The infiltration was neither dependent on the type of UHMWPE (powder or bulk) nor on the temperature. The polymer was so well anchored inside the titanium foam pores that the shear forces for the compounds exceeded the shear strength obtained for a UHMWPE-cylinder. This effect was due to the increased stiffness of the compound plug. Uniaxial compression of the titanium foams after the shear-off of the polymer revealed yield strengths ranging from 50 – 88 MPa for porosities of 62 – 73%. The Ø16 mm samples yielded beyond physiological loads in the knee (≥ 10x body weight) and behaved in a strain hardening and fully ductile manner, reaching deformations of at least 50 % of their initial height without the appearance of macroscopically visible cracks. For smaller plug diameters down to Ø8 mm, however, the lower porosity / higher strength foam should be used to limit elastic deformation of the compound to < 0.1 mm. Pore size did not significantly influence the strength and stiffness values. The elevated coefficient of friction between cartilage and UHMWPE of about 1 was not negatively affected by the presence of the gap. The height loss of the cartilage pin after 1 hour (respectively after 3600 reciproque wear cycles) was 0.2 ± 0.1 mm using a flat disc. For discs with a 1 mm wide V-notch, the wear increased to 0.9 ± 0.3 mm. Conclusions. The tested titanium foams are well suited to act as an anchoring material in the subchondral bone as mechanical properties can be tailored by choosing the adequate porosity and as bone ingrowth has previously been demonstrated for the used pore sizes. UHMWPE is not an ideal gliding partner against cartilage because the friction coefficients of frictions were high. The presence of a V-notched gap was detrimental for cartilage wear. More hydrophilic polymers like PCU should be tested as potential gliding materials

We maintain a database on 1000 femoral revisions using extensively porous-coated stems. Using femoral rerevision for any reason as an endpoint, the survivorship is 99 ± 0.8% (95% confidence interval) at 2 years, 97 ± 1.3% at 5 years, 95.6 ± 1.8% at 10 years, and 94.5 ± 2.2% at 15 years. Similar to Moreland and Paprosky, we have identified prerevision bone stock as a factor affecting femoral fixation. When the cortical damage involved bone more than 10 cm below the lesser trochanter, the survivorship, using femoral rerevision for any reason or definite radiographic loosening as an endpoint, was reduced significantly, as compared with femoral revisions with less cortical damage. In addition to patients with Paprosky type 3B and 4 femoral defects there are rare patients with femoral canals smaller than 13.5 mm or larger than 26 mm that are not well suited to this technique. Eight and 10 inch stems 13.5 mm or smaller should be used with caution if there is no proximal bone support for fear of breaking. Patients with canals larger than 18 mm may be better suited for a titanium tapered stem with flutes. While a monolithic stem is slightly more difficult for a surgeon to insert than a modular femoral stem there is little worry about taper junction failure