Cell culture on tissue culture plastic (TCP) is widely used across biomedical research to understand the in vivo environment of a targeted biological system. However, growing evidence indicates that the characteristics of cells investigated in this way differ substantially from their characteristics in the human body. The limitations of TCP monolayer cell cultures are especially relevant for chondrocytes, the cell population responsible for producing cartilage matrix, because their zonal organization in hyaline cartilage is not preserved in a flattened monolayer assay. Here, we contrast the response of primary human chondrocytes to inflammatory cytokines, tumor necrosis factor-alpha and interferon-gamma, via transcriptional, translational, and histological profiling, when grown either on TCP or within a 3D cell pellet (scaffold-less). We focus on anti-apoptotic (Bcl2), pro-apoptotic (Bax, Mff, Fis1), and senescent (MMP13, MMP1, PCNA, p16, p21) markers. We find that the 3D environment of the chondrocyte has a profound effect on the behavior and fate of the cell; in TCP monolayer cultures, chondrocytes become anti-apoptotic and undergo senescence in response to inflammatory cytokines, whereas in 3D cell pellet cultures, they exhibit a pro-apoptotic response. Our findings demonstrate that chondrocyte culture environment plays a pivotal role in cell behavior, which has important implications for the clinical applicability of in vitro research of cartilage repair. Although there are practical advantages to 2D cell cultures, our data suggest researchers should be cautious when drawing conclusions if they intend to extrapolate findings to in vivo phenomena. Our data demonstrates opposing chondrocyte responses in relation to apoptosis and senescence, which appear to be solely reliant on the environment of the culture system. This biological observation highlights that proper experimental design is crucial to increase the clinical utility of cartilage repair experiments and streamline their translation to therapy development

Abstract. BACKGROUND. Cell culture on tissue culture plastic (TCP) is widely used across biomedical research to understand the in vivo environment of a targeted biological system. However, growing evidence indicates that the characteristics of cells investigated in this way differ substantially from their characteristics in the human body. The limitations of TCP monolayer cell cultures are especially relevant for chondrocytes, the cell population responsible for producing cartilage matrix, because their zonal organization in hyaline cartilage is not preserved in a flattened monolayer assay. OBJECTIVE. Here, we contrast the response of primary human chondrocytes to inflammatory cytokines, tumor necrosis factor-alpha and interferon-gamma, via transcriptional, translational, and histological profiling, when grown either on TCP or within a 3D cell pellet (scaffold-less). We focus on anti-apoptotic (Bcl2), pro-apoptotic (Bax, Mff, Fis1), and senescent (MMP13, MMP1, PCNA, p16, p21) markers. RESULTS. We find that the 3D environment of the chondrocyte has a profound effect on the behavior and fate of the cell; in TCP monolayer cultures, chondrocytes become anti-apoptotic and undergo senescence in response to inflammatory cytokines, whereas in 3D cell pellet cultures, they exhibit a pro-apoptotic response. CONCLUSION. Our findings demonstrate that chondrocyte culture environment plays a pivotal role in cell behavior, which has important implications for the clinical applicability of in vitro research of cartilage repair. Although there are practical advantages to 2D cell cultures, our data suggest researchers should be cautious when drawing conclusions if they intend to extrapolate findings to in vivo phenomena. Our data demonstrates opposing chondrocyte responses in relation to apoptosis and senescence, which appear to be solely reliant on the environment of the culture system. This biological observation highlights that proper experimental design is crucial to increase the clinical utility of cartilage repair experiments and streamline their translation to therapy development. 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

Abstract. Objectives. Mesenchymal stromal/stem cells (MSCs) are increasingly recognized as regulators of immune cells during disease or tissue repair. During these situations, the extracellular matrix (ECM) is very dynamic and therefore, our studies aim to understand how ECM influences the activity of MSCs. Methods. Human MSCs cultured on tissue culture plastic (TCP) and encapsulated within collagen type I, fibrin, or mixed Collagen-Fibrin were exposed to low dose TNFα and IFNɣ. Transcription profiles were examined using bulk RNA sequencing (RNAseq) after 24h of treatment. ELISA, Western blot, qPCR and immunofluorescence were employed to validate RNAseq results and to investigate the significance of transcriptional changes. Flow cytometry evaluated monocyte/macrophage phenotype. Results. Previously, we showed that human MSC expression of TNFAIP6 and CXCL10 in 3D environments is significantly upregulated in response to pro-inflammatory stimuli. Here, RNAseq revealed that there were 2,085 highly significant upregulated genes in 3D matrices compared to TCP. Notably, >90% of highly expressed genes (including FOSB, FOS and TNFAIP6) were shared in all hydrogels. Gene ontology confirmed the TNF signalling pathway among the most significantly represented. Protein-protein interaction predictions identified TNF-alpha/NF-kappa B and AP1 pathways as differentially influenced by the hydrogel environment. Using inhibitors to these pathways, NFkB, but not AP1, impacted on the upregulation of TNFAIP6 and CXCL10 in 3D culture. Conditioned media from these studies was added to cultures of human monocytes with distinct changes in the resulting macrophage phenotype. MSCs in a 3D environment promoted a greater acquisition of the M2 repair macrophage phenotype and impacted on the numbers of pro-inflammatory M1 macrophages. Conclusion. These data provide further evidence that the immunomodulatory action of human MSCs can be influenced by the surrounding structural environment. These observations have significance for understanding the events that following skeletal injury and the potential to be exploited in preconditioning MSCs for cell therapy

The management of bone defects and impaired fracture healing remains one of the most challenging clinical problems. Several treatments exist to aid in the healing of large bone defects, including biologics such as recombinant human bone morphogenetic protein-2 (BMP-2), yet all have met with limited success. Regeneration of bone requires a coordinated network of molecular signals where the local mechanical environment plays a major role in the success of the healing process. The mechanical environment itself is determined by the stiffness of the implant used to stabilize the fracture and weight-bearing, and if fixation is either too flexible or too rigid the healing might fail. The hypothesis is that the healing of large-segmental bone defects and fractures can be accelerated by the imposition of an appropriate mechanical environment. An overview of the progress made in this research area on how the amount of rhBMP-2 could be reduced and its effectiveness increased by providing an optimized mechanical environment to achieve bone union will be presented. Additionally, the latest findings of improved fracture healing through the manipulation of fixation stability introducing a potential clinical strategy to improve the healing outcome of unstable fractures, particularly for non-unions through increased stabilization, will be discussed

We share our experiences in designing a complete simulator prototype and provide the technological basis to determine whether an immersive medical training environment for vertebroplasty is successful. In our study, the following key research contributions were realised: (1) the effective combination of a virtual reality surgical simulator and a computerised mannequin in designing a novel training setup for medical education, and (2) based on a user-study, the quantitative evaluation through surgical workflow and crisis simulation in proving the face validity of our immersive medical training environment. Medical simulation platforms intend to assist and support surgical trainees by enhancing their skills in a virtual environment. This approach to training is consistent with an important paradigm shift in medical education that has occurred over the past decade. Surgical trainees have traditionally learned interventions on patients under the supervision of a senior physician in what is essentially an apprenticeship model. In addition to exposing patients to some risk, this tends to be a slow and inherently subjective process that lacks objective, quantitative assessment of performance. By proposing our immersive medical simulator we offer the first shared experimental platform for education researchers to design, implement, test, and compare vertebroplasty training methods. We collected feedback from two expert and two novice residents, on improving the teaching paradigm during vertebroplasty. In this way, this limits the risks of complications during the skill acquisition phase that all learners must pass through. The complete simulation environment was evaluated on a 5-pt Likert scale format: (1) strongly disagree, (2) disagree, (3) neither agree nor disagree, (4) agree, and (5) strongly agree. When assessing all aspects of the realism of the simulation environment, specifically on whether it is suitable for the training of technical skills team training, the participating surgeons gave an average score of 4.5. Additionally, we also simulated a crisis simulation. During training, the simulation instructor introduced a visualisation depicting cement extravasation into a perivertebral vein. Furthermore, the physiology of the computerised mannequin was influenced by the instructor simulating a lung embolism by gradually lowering the oxygen saturation from 98% to 80% beginning at a standardised point during the procedure. The simulation was stopped after the communication between the surgeon and the anaesthetist occurred which determined their acknowledgment that an adverse event occurred. The realism of this crisis simulation was ranked with an average score of 4.75. To our knowledge this is the first virtual reality simulator with the capacity to control the introduction of adverse events or complication yielding a wide spectrum of highly adjustable crisis simulation scenarios. Our conclusions validate the importance of incorporating surgical workflow analysis together with virtual reality, human multisensory responses, and the inclusion of real surgical instruments when considering the design of a simulation environment for medical education. The proposed training environment for individuals can be certainly extended to training medical teams

An understanding of the remodelling of tendon is crucial for the development of scientific methods of treatment and rehabilitation. This study tested the hypothesis that tendon adapts structurally in response to changes in functional loading. A novel model allowed manipulation of the mechanical environment of the patellar tendon in the presence of normal joint movement via the application of an adjustable external fixator mechanism between the patella and the tibia in sheep, while avoiding exposure of the patellar tendon itself. Stress shielding caused a significant reduction in the structural and material properties of stiffness (79%), ultimate load (69%), energy absorbed (61%), elastic modulus (76%) and ultimate stress (72%) of the tendon compared with controls. Compared with the material properties the structural properties exhibited better recovery after re-stressing with stiffness 97%, ultimate load 92%, energy absorbed 96%, elastic modulus 79% and ultimate stress 80%. The cross-sectional area of the re-stressed tendons was significantly greater than that of stress-shielded tendons. The remodelling phenomena exhibited in this study are consistent with a putative feedback mechanism under strain control. This study provides a basis from which to explore the interactions of tendon remodelling and mechanical environment

Introduction. Civilian fractures have been extensively studied with in an attempt to develop classification systems, which guide optimal fracture management, predict outcome or facilitate communication. More recently, biomechanical analyses have been applied in order to suggest mechanism of injury after the traumatic insult, and predict injuries as a result of a mechanism of injury, with particular application to the field so forensics. However, little work has been carried out on military fractures, and the application of civilian fracture classification systems are fraught with error. Explosive injuries have been sub-divided into primary, secondary and tertiary effects. The aim of this study was to 1. determine which effects of the explosion are responsible for combat casualty extremity bone injury in 2 distinct environments; a) in the open and b) enclosed space (either in vehicle or in cover) 2. determine whether patterns of combat casualty bone injury differed between environments Invariably, this has implications for injury classification and the development of appropriate mitigation strategies. Method. All ED records, case notes, and radiographs of patients admitted to the British military hospital in Afghanistan were reviewed over a 6 month period Apr 08-Sept 08 to identify any fracture caused by an explosive mechanism. Paediatric cases were excluded from the analysis. All radiographs were independently reviewed by a Radiologist, a team of Military Orthopaedic Surgeons and a team of academic Biomechanists, in order to determine the fracture classification and predict the mechanism of injury. Early in the study it became clear that due to the complexity of some of the injuries it was inappropriate to consider bones separately and the term ‘Zone of Insult’ (ZoI) was developed to identify separate areas of injury. Results. 62 combat casualties with 115 ZoIs (mean 1.82 zones) were identified in this study. 34 casualties in the open sustained 56 ZoIs (mean 1.65); 28 casualties in the enclosed group sustained 59 ZoIs (mean 2.10). There was no statistical difference in the mean ZoIs per casualty in the open vs enclosed group (Student t-test, p=0.24). Open fractures were more prevalent in the open group compared to the enclosed group (48/59 vs 20/49, Chi-squared test p<0.001). Of the casualties in the open, 1 zone of injury was due to the primary effects of blast, 10 a combination of primary and secondary blast zones, 23 due to secondary effects and 24 from the tertiary effects of blast. In contrast, there were no primary or combined primary and secondary blast zones and only 2 secondary blast zones in the enclosed group. Tertiary blast effects predominated in the enclosed group, accounting for 96% of injury zones (57/59). Analysis of the pattern of injury revealed that there were a higher proportion of lower limb injuries in the Enclosed group (54/59) compared to the Open group (40/58, Chi-squared p<0.05). In the Open group the mechanism of lower limb injury was more evenly distributed amongst mixed primary and secondary blast effects (10), secondary (10) and tertiary (20). In the enclosed group, lower limb injuries were almost exclusively caused by tertiary blast effects (47/48). A similar pattern was also seen in the Upper limb with 4/5 in the enclosed group was injured by tertiary effects compared to 4/18 in the Open Group. In the open group fragmentation injury was the predominant cause of injury (13/18). Conclusions. This data clearly demonstrates two distinct injury groups based upon the casualties' environment. The enclosed environment afforded by buildings and vehicles appears to mitigate the primary and secondary effects of the explosion. However, tertiary blast effects were the predominant mechanism of injury, with severe axial loading to the lower extremity being a characteristic of the fractures seen. In contrast, secondary fragments from the explosion were more likely to result in fractures of casualties caught in the open. The development of future mitigation strategies must be focused on reducing all the different mechanisms of injury caused by an explosion. This will require a better understanding on the effects of bone in high strain environments. This method of forensic biomechanics involving clinicians and engineers, combined with accurate physical and numerical simulations can form the basis in reducing the injury burden to the combat soldier

Introduction. One method of surgical site infection prevention is lowering intraoperative environmental contamination. We sought to evaluate our hospitals operating room (OR) contamination rates and compare it to the remainder of the hospital. We tested environmental contamination in preoperative, intraoperative and postoperative settings of a total joint arthroplasty patient. Materials & Methods. 190 air settle plates composed of trypsin soy agar (TSA) were placed in 19 settings within our hospital. Locations included the OR with light and heavy traffic, with and without masks, jackets, and shoe covers, sub-sterile rooms, OR hallways, sterile equipment processing center, preoperative areas, post-anesthesia care units, orthopaedic floors, emergency department, OR locker rooms and restrooms, a standard house in the local community, and controls. The plates were incubated in 36 degrees celsius for 48 hours and colony counts were recorded. Numbers were averaged over each individual area. Results. The highest CFU was the OR locker room at 28 CFU/plate/hr. Preoperative & post anesthesia care unit holding areas were 7.4 CFU & 9.6 CFU, respectively. The main orthopaedic surgical ward had 10.0 CFU/plate/hr, while the VIP hospital ward had 17.0 CFU/plate/hr. The OR environment all had low CFUs. A live OR had slightly higher CFUs than ones without OR personnel. The OR sub-sterile room had 5.2 CFU/plate/hr, and the OR hallway had 11.2 CFU/plate/hr. The local community household measured 5.6CFU/plate/hr. Discussion. In comparison to the local community household, the OR locker room, restrooms, hospital orthopaedic wards, ED, pre-operative holding, PACU and OR hallway all had higher airborne contamination than the local household in our surrounding community. We were surprised to find some areas with high rates of contamination. Our hospital has since increased environmental cleaning and monitoring of these areas with improved effect. Based on our results, we can recommend environmental sampling as a simple, fast, inexpensive tool to monitor airborne contamination

Unresolved inflammatory processes in tendon healing have been related to the progression of tendinopathies. Thus, the management of tendon injuries may rely on cell-based strategies to identify and modulate tendon inflammatory cues. Pulsed electromagnetic field (PEMF) has been approved by FDA for orthopedics therapies and has been related to a reduction in pain and to improve healing. However, the influence of PEMF in tendon healing remains largely unknown. Human tendon resident cells (hTDCs) were cultured in an inflammatory environment induced by exogenous supplementation of IL-1β and their response assessed after exposure to different PEMF treatments. This study demonstrates that IL-1β induced up-regulation of pro-inflammatory factors (IL-6 and TNFα) and extracellular matrix components (MMP−1, −2, −3) whereas reduces the expression of TIMP-1, suggesting IL-1β as a candidate inflammation model to study hTDCs response to inflammation cues. Moreover, in both homeostatic and inflammatory environments, hTDCs respond differently to PEMF treatment suggesting that cells are sensitive to magnetic field parameters such as strength (1.5 – 5mT), frequency (5–17Hz) and duration (10–50% duty cycle, dc). Among the conditions studied, PEMF treatment with 4mT/5Hz/50%dc suppresses the inflammatory response of hTDCs to the IL-1β stimulation, as evidenced by the decreases amount of IL-6, TNFα and downregulation of MMP-1, −2, −3 and COX-2, IL-8, IL-6, TNFα genes. These results demonstrate the potential of PEMF, in particular 4mT/5Hz/50%dc PEMF in treating tendon inflammation suppressing the inflammatory stimulation induced by IL-1β, which may be beneficial for tendon healing strategies

Introduction: the NHS places emphasis on outcomes and patient partnerships but measuring these factors is problematic. In 2003 the Spinal Assessment Clinic (SAC) moved from an old style hospital to a new PFI building providing an opportunity to audit the influence of environment on operational activity. Objective: Does environment influence satisfaction with care and objective outcome in patients with LBP?. Method: Patients attending the SAC two months prior to relocation and two months following completed a Low Back Outcome Score (LBOS) and a satisfaction survey. Results: The analysis of the satisfaction surveys demonstrated that the patients did not perceive any real difference in the two locations despite the significant age difference, layout and internal standards of the buildings. The satisfaction of patients at both sites was analysed using a number of factors- the care provided was 79% before the move and 82% afterwards, their understanding of a nurse led service was rated as 73% and 85% respectively. Evaluation of the quality of information demonstrated that their questions had been answered well 78% and 75% respectively and the confidence and trust in the person providing the care was 91% and 89%. Failure by the IT department in delivering effective links to hospital computer system resulted in the LBOS data not being completed in the period following the move with logistical difficulties in clinic organisation. Conclusion: despite the difficulty of moving and problems encountered by staff from the SAC the patient did not perceive any alteration in quality

Introduction

Most western countries have implemented fast-track hip fracture aiming at surgery within 24 hours, since the mortality rate hereafter rises markedly.

In Greenland, it is not achievable to operate within 24 hours. Arctic people live in sparsely populated areas and Greenland's population is scattered along the vast coastline. All patients must be chartered to Nuuk by airplane which can take up till several days to weeks, due to logistics and the Arctic weather. This presents a challenge regarding adhering to western guidelines. The operative delay may be acceptable though, as it is the impression that the Greenlandic population survives and endures better than patients of western populations.

However, as data are lacking, we aimed to describe mortality among hip fracture patients in Greenland taking frailty and comorbidities into account.

Several previous studies have examined the mechanical environment in the femur using computational modelling. In particular the proximal femur has been extensively studied using finite element (FE) analyses. This study considers the issues associated with modelling with special interest in the distal femur. FE models require appropriate input on the geometry of the system being considered, material properties of different components, loading regimes and boundary conditions (i.e. the manner in which the system is supported). This study focuses on the last two of the above. A number of models with variable levels of complexity; and different boundary and loading conditions were considered. The simplest loading and boundary conditions considered comprised load applications at the tibio-femoral joint with the proximal femur artificially restrained. More complex models had the femur fully supported on muscles and ligaments. In each case the stress-strain environment in the femur was examined. The results show that the sophistication of the model needs to be based on the answers being sought from the analysis. Some good predictions on the mechanical environment can be made with relatively crude models. For example the stress-strain behaviour in the vicinity of the knee joint was found to be reasonably well predicted by the model that was artificially restrained in the mid-femoral region. Further while different models can be used for comparing different scenarios (e.g. forces during the gait cycle) true quantitative measures are strongly dependent on experimental loading data. The study also shows that it is important to generate and evaluate models of increasing complexity in order to maintain transparency with respect to the influence of different parameters associated with loading and boundary conditions

Aims

Arthroplasty has been shown to generate the most waste among all orthopaedic subspecialties, and it is estimated that hip and knee arthroplasty generate in excess of three million kg of waste annually in the UK. Infectious waste generates up to ten times more CO2 compared with recycled waste, and previous studies have shown that over 90% of waste in the infectious stream is misallocated. We assessed the effect of real-time waste segregation by an unscrubbed team member on waste generation in knee and hip arthroplasty cases, and compared this with a simple educational intervention during the ‘team brief’ at the start of the operating list across two sites.

Cementation is an important part of arthroplasty operations. Recent publication of results of Charnley total hip replacement found a rate of early aseptic loosening of 2.3% at 5 years following surgery across a NHS region. There are possibly many reasons for early loosening but precise reasons are still not fully understood, however, it is felt that cementation technique is very important. There seems to be a number of factors involved such as cement mixing techniques and conditions, physical properties of the cement, cementation and surgical techniques, bone-cement interface as well as bone- prosthesis interface. The purpose of this study was to evaluate the effectiveness of the clinical environment in producing bone cement of predictable mechanical and physical properties, and how those properties compare with published data. The investigation compared samples of bone cement, taken from material prepared and used in surgery with cement samples prepared under controlled laboratory conditions and in accordance with ISO materials testing standards. During 2000–01, 10 total hip replacements were selected for study. All operations involved the use of CMW1 (DePuy) radio-opaque cement, which was mixed using the Vacumix system. In this cohort, all femoral cementations were performed using an 80g cement mix. After careful preparation of the femoral canal, the scrub nurse mixed the cement in accordance with the manufacturer’s instructions. The cement was introduced into the femoral canal, via a nozzle, using the cementation gun and a pressurizer. Following introduction of cement into the canal, the nozzle and cement contained within, was broken off the gun distal to the pressurizer. Once cured, the cement samples were removed from the nozzle, sectioned, and mechanically tested. Due to this novel sample preparation procedure, the tested cement was expected to exhibit mechanical and physical properties characteristic of the cement present in the femoral canal. Samples of CMW1 (Vacumixed) of similar mass and aspect ratio were produced within the laboratory, in accordance with the manufacturers mixing instructions. PMMA bone cement is a brittle, glassy polymer that is susceptible to stress raisers, such as pores, which can reduce the load carrying ability, which in vivo is predominantly compressive in nature. Published mechanical properties of PMMA bone cement vary somewhat, reflecting the dependence of properties on flaw distribution. The density, which provides a measure of porosity, hardness and ultimate compressive strength of the cement samples was measured and compared. The surgical samples were found to be very consistent in compressive strength (121 ± 6 MPa), density (1.20 ± 0.02 gcm. −3. ) and hardness (23.2 ± 1.6 VHN) and closely matched the mechanical properties of the cement mixed in the laboratory. This study suggests that for the studied cement and mixing regime, the clinical environment is capable of producing a well-controlled cement product that has reproducible and predictable mechanical properties. Further, the novel sample preparation procedure used suggests that the cement within the femoral cavity should demonstrate equally predictable, mechanical and physical properties

Background. Intervertebral disc cells exist in a challenging physiological environment. Disc degeneration occurs early in life implying that disc cells may no longer be able to maintain a functional tissue. We hypothesise that disc cells have a stress response different from most other cells because of the disc environment. We have compared the stress response of freshly isolated and cultured bovine nucleus pulposus (NP) cells with bovine dermal fibroblasts, representative of cells from a vascularised tissue. Methods. Freshly isolated and passaged bovine NP cells and dermal fibroblasts were cultured for 3 days then subjected to either thermal stress at 45°C for 1h followed by recovery times of 6, 24 and 48h or nutrient stress involving culture without serum for 6, 24 and 48 h. At each time point, cell number and viability were assessed and heat shock protein 70 (Hsp70) measured in cell lysates by an enzyme-linked immunosorbent assay. Results. In response to thermal stress, both freshly isolated and passaged dermal fibroblasts and also passaged NP cells showed a rapid elevation of Hsp70. In contrast, freshly isolated NP cells exhibited an attenuated Hsp70 response. With nutrient stress, Hsp70 increased with time in all dermal fibroblasts and passaged NP cells after 24 h, but freshly isolated NP cells responded differently again, producing less Hsp70 than controls. Conclusion. Freshly isolated bovine NP cells have a reduced response to applied stresses. This pilot study suggests that NP disc cells may have adapted to their physiologically challenging in vivo environment by attenuating their response to environmental stress. No conflicts of interest. Sources of Funding: The Wolfson Charitable Trust and Genodisc (EC's 7. th. Framework Programme (FP7, 2007–2013) under grant agreement no. HEALTH-F2-2008-201626). This abstract has not been previously published in whole or substantial part nor has it been presented previously at a national meeting

Study Aim. Femoral components used in total knee arthroplasty (TKA) are primarily designed on the basis of kinematics and ease of fixation. This study considers the stress-strain environment in the distal femur due to different implant internal geometry variations (based on current industry standards) using finite element (FE) analyses. Both two and three dimensional models are considered for a range of physiological loading scenarios – from full extension to deep flexion. Issues associated with micro-motion at the bone-implant interface are also considered. Materials and methods. Two (plane strain) and three dimensional finite element analyses were conducted to examine implant micro-motions and stability. The simple 2D models were used to examine the influence of anterior-posterior (AP) flange angle on implant stability. AP slopes of 3°, 7° and 11° were considered with contact between bone and implant interfaces being modeled using the standard coulomb friction model. The direction and region of loading was based on loading experienced at full extension, 90° flexion and 135° flexion. Three main model variations were created for the 3D analyses, the first model represented an intact distal femur, the second a primary implanted distal femur and the third a distal femur implanted with a posterior stabilising implant. Further each of the above 3D model sets were divided into two group, the first used a frictional interface between the bone and implant to characterise the behavior of uncemented implants post TKA and the second group assumed 100% osseointegration had already taken place and focused on examining the subsequent stress/strain environment in the femur with respect to different femoral component geometries relative the intact distal femur model. Results and Discussion. Analyses indicate a trend relating the slope of the anterior-posterior (AP) flange to implant loosening at high flexion angles for uncemented components. Once cemented, this becomes less important. Results from the 3D analyses show that the posterior stabilising implant causes stress concentrations which can lead to bicondylar fatigue fracture. All femoral components cause stress shielding in cancellous bone particularly when they are fully bonded. Investigations into implant micromotion show that revision implants with box sections provided more resistance to micromotion than the pegged primary implants. However for the gait cycle tested the maximum recorded micromotion of both implants was well within acceptable levels for osseointegration to occur

Poly (vinyl alcohol) (PVA) hydrogel with high water content is one of the potential materials for artificial cartilage. In the previous study, the wear behavior of PVA hydrogel prepared by freeze-thawing (FT) method (PVA-FT gel) showed the excellent friction and wear property in simulated biological environment. However, the improvement of mechanical strength and wear resistance would be also needed for clinical application of PVA hydrogel as artificial cartilage. The different kind of physically-crosslinked PVA hydrogels prepared by cast-drying (CD) method (PVA-CD gel) and hybrid method of FT and CD (PVA-CD on FT hybrid gel) were also developed, and these two hydrogels have different mechanical properties and showed low friction compared with PVA-FT gel in saline. In this study, PVA hydrogel prepared by CD and hybrid methods were newly developed and friction and wear behavior of PVA-CD gel and PVA-CD on FT hybrid gel were evaluated in simulated biological environment. A sliding pair of an ellipsoidal reciprocating upper specimen of hydrogel and a flat stationary lower specimen of hydrogel was tested in reciprocating friction test. The thicknesses of PVA-CD gel and PVA-CD on FT hybrid gel were 2.0mm and 1.7mm, respectively. The applied load was 2.94 N. The sliding velocity was 20 mm/s and the total sliding distance was 1.5 km. In this study, solutions that contain hyaluronic acid, phospholipid and proteins were prepared as simulated synovial fluid and used as a lubricant for friction test. Molecular weight of sodium hyaluronate was 9.2×10. 5. L-alpha dipalmitoylphosphatidylcholine (DPPC) was selected as phospholipid constituent and was dispersed in saline as liposome. This liposomal solution was used as a base lubricant. Albumin and gamma-globulin, which are main protein constituents in natural synovial fluid, were used as additives as protein constituents. As shown in Fig.1, PVA-CD gel showed low friction such as below 0.02 at initial state of friction test. However, friction coefficient of PVA-CD gel rapidly increased and reached to about 0.5. In contrast, PVA-CD on FT hybrid gel kept low friction within the friction test. After friction test, many deep scratches were observed on the worn surface of PVA-CD gel (Figs. 2(a)-(c)). In contrast, the original surface structure of PVA-CD on FT hybrid gel almost remained while some scratches were observed (Figs. 2(d)-(f)). These results indicated that PVA-CD gel could show low friction but low wear resistance. The hybridization of FT and CD improved the wear resistance of PVA-CD gel. Therefore, the hybridization of FT and CD method is one of the prospective preparation methods of artificial cartilage with low friction and low wear. It is important to elucidate the mechanism of excellent lubricating property of PVA-CD on FT hybrid gel and develop the highly-functioned artificial hydrogel cartilage with low friction and high wear resistance

Bones meet competing demands both structurally and metabolically with an ability to “functionally adapt” to the surrounding environment. Diets high in saturated fat and sucrose (HFS) can adversely affect bone by limiting calcium availability. Conversely, applying a mechanical stimulus, appropriate in magnitude, frequency, and rate has been shown to be osteogenic. Thus, we hypothesized that groups subject to a mechanical loading would incur skeletal benefits, whereas exposure to a HFS diet would adversely affect structural integrity. We also proposed that despite the osteogenic potential of loading stimuli, the calcium-limiting effects of a HFS diet would result in a net decrease in bone structural properties, when considered in combination. Female mice underwent non-invasive exogenous cantilever bending of the right tibia with a 1Hz trapezoidal waveform for 60s, five days per week, for thee weeks. Loading was calibrated to induce peak strain magnitudes of 1000 microstrain. Mice were randomly assigned to one of two dietary cohorts: high-fat-sucrose (HFS, n=36) or adjusted starch diets (n=36). Mice were further subdivided into groups based on loading status: control, sham, or loaded. Upon sacrifice, tibiae were dissected; morphometrical and mechanical properties were assessed and compared. Control mice fed a HFS diet had significantly reduced cross-sectional area, cortical thickness, maximal load, and energy to failure when compared to control mice fed the starch diet. No changes in material properties were seen. Mice eating a HFS diet as well as experiencing mechanical loading had significantly greater cross-sectional area, energy to failure, and maximal load when compared to control mice fed a HFS diet, but had reduced structural properties when compared with loaded mice within the starch cohort. To date, bone structural properties, and not material properties were adversely affected as a result of ingesting a HFS diet. A diet effect was observed, between control mice fed a HFS diet and control mice fed a starch diet, with the former group experiencing the negative affects previously associated with HFS diets in rodents. Presently, a load effect was only observed within the HFS cohort

British military forces remain heavily committed in both Iraq and Afghanistan. A recent workload analysis from Op HERRICK identified a high surgical workload, particularly orthopaedic, under the care of a sole consultant orthopaedic surgeon. There are no orthopaedic training posts in UK that consistently provide training in ballistic trauma. In order to prepare Military orthopaedic trainees for future deployment, a new orthopaedic registrar post, on Op HERRICK, was created. Prospective analysis of trainee and trainer operative logbooks, between Jan 27th and March 24th 2008, was performed. Records were kept of orthopaedic and postgraduate teaching schedules, audit and research projects and all OCAP training assessments. One hundred and fifty-seven cases and 272 procedures were performed during the study period. Sixty-two per cent of cases were orthopaedic. Fourteen major amputations were performed and 7 external fixators applied. Five fasciotomies, 9 skeletal traction pins were inserted and 7 skin grafting procedures were performed. Limb debridement was the most common procedure (n=59). Eleven per cent of cases were children and 50 per cent of cases were emergencies. Thirty-eight per cent of cases were performed out of hours (18.00–08.00 hrs). Mean operating hours per week was 35 hrs. Four Procedure Based Assessments were performed and 16 hours of postgraduate education was conducted during the deployment. Two major audits were initiated and five publications were prepared, one has already been accepted for publication. Trainee exposure to high-energy transfer trauma is high when compared to that seen in the NHS. The numbers of certain index procedures, such as external fixation, is similar to those achieved by an average orthopaedic trainee in six years of higher surgical training. The opportunity for one-on-one training exceeds that available in the NHS and learning and academic opportunities are maximised due to the close working environment

Introduction and Objective

It is widely accepted that interfragmentary strain stimulus promotes callus formation during secondary bone healing. However, the impact of the temporal variation of mechanical stimulation on fracture healing is still not well understood. Moreover, the minimum strain value that initiates callus formation is unknown. The goal of this study was to develop an active fixation system that allows for in vivo testing of varying temporal distribution of mechanical stimulation and that enables detection of the strain limit that initiates callus formation.