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During defeat of high velocity bullets and fragmentation, large deformations have been shown to occur on the inside of non-metallic helmet shells. If these deformations contact the underlying head there is the potential to cause injury, termed as Behind Helmet Blunt Trauma (BHBT). A method of assessing BHBT is required to fully understand the protective capability of a helmet system. Existing methods using synthetic head models are limited in their ability to predict injury outcome as a result of a lack of available injury criteria. The aim of this study was to improve the prediction of cranial fracture outcomes associated with BHBT, focusing on the effect of impact curvature and flat face diameter. Representative impact curvatures and flat face diameters were derived from helmet back face deformation measurements in free-air. An instrumented projectile was used to deliver a repeatable impact to a Bovine Scapula Model (BSM); the BSM being a fracture analogue for the cranium. Cranial fracture risk curves were developed using BSM fracture outcomes. These were developed for the different curvatures and flat face diameters tested, using the parameters of peak impact force, impact velocity, bone thickness considered in conjunction with impact velocity, and the Blunt Criterion (BC). It was concluded that flat impact diameter and radius of curvature should be measured within BHBT assessment to improve the accuracy of cranial fracture prediction. To support application of the risk curves to BHBT assessment methods, it was recommended that fracture outcome should be investigated in terms of the effect of using a rigid projectile when compared to helmet deformation. BHBT assessment methods should consider how to achieve consistent and representative stand-off. Testing should also be completed on full helmet systems as opposed to flat material samples.

A new paradigm is coming to the forefront of chronic wound research and a potential treatment target; this is the wound pH. Non-healing wounds typically have a more alkaline pH, and from previous experimental studies, it appears that attempts should be made to reduce pH and shift the wound toward an acidic environment. This investigation aimed to determine the effects of pH alone and the combination of altering pH and bacterial biofilms on key wound healing processes in vitro. Normal healthy equine skin fibroblasts (NF) and equine chronic wound fibroblasts (CF) were cultured in pH 6, 7.5 and 9 conditions or planktonic conditioned media (PCM) and biofilm conditioned media (BCM) titrated to pH 6, 7.5 and 9. After 24 hours conditioned media was collected and analysed for the presence of collagen, fibronectin, glycosaminoglycans (GAGs) and tropoelastin. Cell migration was analysed over 48 hours: a scratch was created on a confluent layer of cells, and then cells were incubated in the different conditions and images taken at 0, 24 and 48hours. Scratch images were analysed using ImageJ and percentage wound closure determined. Results revealed that pH had no effect on ECM abundance from CF, however, it was evident that there was a lower amount of these ECM molecules from CF compared to NF. BCM alone affected ECM abundance with no further effects seen with pH alterations. Migration of CF was significantly diminished in pH 9 conditions compared with pH 6 and pH 7.5. NF were not affected by alkaline pH, with similar migration rates observed in pH 7.5 and pH 9 conditions. The reduced rate of migration observed in alkaline conditions may be explained by the reduced abundance of ECM from CF. Cell migration was significantly affected by the combination of BCM and alkaline pH, with significant inhibition compared to other pH and PCM conditions. To my knowledge this is the first study which has investigated the effect of pH on wound related parameters and the combined effect of pH and bacterial biofilms on wound healing. This study demonstrates that pH does play a role in wound healing. However, it is important to note that many other factors are involved in chronic wounds and should be taken into account when developing future research. Findings here warrant further investigation into pH and wound healing in vivo. Simply making sure that the wound remains at neutral pH and does not increase to unfavourable alkaline levels may be sufficient to prevent wounds from progressing to a chronic non-healing state.

Assessment of bilateral asymmetry (BA) in lower-limbs is crucial in the field of sport rehabilitation as it stands on the physical capabilities of athletes. Clinicians, in their daily practice, aim to objectively standardise their measurements when assessing athletes’ performance or produce norms. Such norms, enable assessors to track athletes’ performance in order to optimise it or on the other hand, to correct their BA as precautionary measure from risk of injury due to improper loading on the musculoskeletal system. Therefore, four main studies were conducted in this thesis to investigate the relationship between key criteria in lower limbs. The first study has sat thresholds for BA and once exceeded the athlete is doomed to be asymmetric. Thresholds were calculated based on the average of absolute asymmetry value percentage (AAV%) in sub-elite athletes [n=139]. An auxiliary study [n=63] was conducted within study one to examine the effect of different loads on the criteria of countermovement jump (CMJ) across jump sets. In study two, threshold norms of elite-athletes were established for four sport-specific groups and, a novel descriptive statistical approach (threshold boundary) was executed to examine the differences between them. In study three [n=144], the relationships between the criteria of CMJ and key criteria in lower limbs were examined based on a novel descriptive statistical approach called agreement in diagnosis of asymmetry. Furthermore, an investigation was conducted also, to examine the effect of manipulating leg length on the force platform profile across different sets of CMJ trials. Lastly, in study four, an investigation was conducted to examine the association between two functional tasks (CMJ and running) by using the asymmetry agreement statistical methodology [n=144]. BA were found throughout all tests and was clinically diagnosed using threshold percentage (Threshold% = mean of AAV% + SD). Moderate to high levels of association were found between criteria. The results from this thesis (0.8-38.1%) indicate that arbitrary percentages of 15% for BA in lower limbs found in literature do not reflect typical thresholds in athletes . Lastly, future studies should be conducted to define how detrimental these asymmetries in term of performance and injury risk. Keywords: biomechanics, asymmetry, imbalance, athletes, lower limbs and threshold.

Radiological features alone do not allow the discrimination between accidental paediatric long bone fractures or those caused by child abuse. Therefore, for those cases where the child is unable to communicate coherently, there is a clinical need to elucidate the mechanisms behind each fracture to provide a forensic biomechanical tool for clinical implementation. 5 months old ovine femurs and tibiae were used as surrogates for paediatric specimens and were subjected to micro-CT scans to obtain their geometrical and material properties. A novel methodology to align long bones so that they would be loaded in a state of pure bending and torsion was developed and compared against the use of a standard anatomical coordinate system. The second moment of area and its coefficient of variation (COV) for each alignment method were calculated to ascertain the reference axes that minimised the effect of eccentric loading. Wilcoxon-signed rank test showed a significant reduction in COV of the second moment of area using this new method, indicating that the bone has a more regular cross-section when this methodology is implemented. The algorithm generated the locations of subject-specific landmarks that can be used as a reference to align the bones in experimental testing. A low-cost platform that synchronized the data acquisition from the tensile testing machine and the strain gauges was built and used with a high speed camera to capture the fracture pattern in four-point bending at three strain rates and in torsion at two different strain rates, following commonly reported case histories. Finite element (FE) models of ovine tibiae in their optimised alignment were generated to replicate the fracture patterns that were obtained. Fracture initiation and propagation was simulated through the use of element deletion with a maximum principal strain criterion. The experiments produced transverse, oblique, and spiral fractures consistently, which were correlated with the finite element analysis, demonstrating the ability of this pipeline to now be adapted for use in forensic analysis.

Injury of ligaments is very common, and a total tear of the anterior cruciate ligament (ACL) demands replacement. Ideally, a graft for ligament replacement should be able to regenerate into a native like ligament, and restore physiological and anatomical function immediately after transplantation. The University of Leeds has developed a protocol to generate an acellular tendon scaffold derived from allograft/ xenograft using decellularisation technology. The aims of the study were to study the differentiation of human bone marrow derived multipotential stromal cells (BM-MSC) seeded onto the decellularised porcine patella tendon scaffold in response to cyclic tensile strain. Porcine patellar tendons were harvested and decellularised using the Leeds protocol. The decellularised tendon scaffolds were then characterised to determine their: (i) acellularity, (ii) histoarchitecture, (iii) extracellular matrix components (iv) levels of DNA (v) sterility, and (vi) biocompatibility. The decellularisation protocol was found to have minimal effect on the tissue histoarchitecture, and consistently generated sterile, non-toxic acellular scaffolds among different batches, with 98 – 99 % DNA removal compared to native tissue. Both porcine and human BM-MSCs were characterised using a range of antibodies to CD markers and trilineage differentiation and shown to have properties consistent with multipotential stromal cells. Human BM-MSCs were seeded directly onto appropriately sized samples of porcine patella tendon scaffolds at 1 x 105 cells.cm-2 for 12 hours, and then transferred to culture wells of TenCell-1 (a physically interactive rig for delivery of cyclic tensile strain). The cell-seeded tendon scaffolds were cultured either statically or with 4, 6 or 8 % cyclic tensile strain for 4/24 hours at 1 Hz, for 7 days. The response of the cells to cyclic tensile strain was investigated using viability assays (Live/Dead assay and ATPlite™ assay), histology, immunohistochemistry and gene expression analysis (RT-qPCR and gel electrophoresis). The mechanical properties of the scaffolds before and after incubation with cells were determined using uniaxial tensile testing. Under 4, 6 and 8 % cyclic tensile strain, the cell seeded scaffolds had a histological appearance of tendon-like tissue. When cultured under 6 and 8 % cyclic tensile strain, there was evidence that the MSCs were differentiating into tenogenic cells by expressing scleraxis, tenascin C, collagen I and collagen III genes. Cell-seeded scaffolds cultured under 6 % cyclic tensile strain had the highest viability and the matrix stiffness, was significantly increased compared to cell-seeded scaffolds cultured at 4 or 8 % cyclic tensile strain. The cell-seeded scaffolds incubated statically for 7 days showed matrix disorganization, had lower cell viability and less cell infiltration compared to samples incubated with cyclic strain.

Rotator cuff (RC) tendinopathy is defined as pain and dysfunction of one or more of the RC tendons (supraspinatus, infraspinatus, subscapularis and teres minor). Inflammation has been associated with this condition. Graduated exercise is the main treatment for RC tendinopathy, and comparable outcomes to surgery, have been reported for the range of conditions associated with RC tendinopathy. However both non-surgical and surgical outcomes are frequently sub-optimal and new treatment methods to support current practice and improve outcomes are required. A questionnaire investigation recruited 261 participants with shoulder pain from eight healthcare locations. Information was collected regarding beliefs and use of nutritional supplements. Supplement use was reported by 38% (100/261) respondents. Of those who were taking supplements, 82% (82/100) were taking them for shoulder pain. Fish oil supplements containing long-chain omega-3 polyunsaturated fatty acids (PUFAs) were the most popular dietary supplements. Long-chain mega-3 PUFAs have been recommended for people with tendinopathy due to their potential to reduce inflammation. This investigation compared exercise and PUFAs to exercise and placebo supplements in the treatment of people with RC tendinopathy. A double-blind placebo controlled randomized controlled trial was conducted in participants with RC tendinopathy recruited from hospital clinics. The active treatment group received nine opaque capsules of MaxEPA providing 1.53g eicosapentaenoic acid (EPA), 1.04g docosahexaenoic acid (DHA) and the placebo group received nine matching placebo capsules where the long-chain omega-3 fatty acids were replaced with oleic acid; all participants attended an eight week exercise programme. Participants were assessed, at pre-randomisation, eight weeks (primary outcome point), three months, six months and 12 months (secondary outcome point). Primary outcome was the Oxford Shoulder Score (OSS). Secondary outcomes included; the Shoulder Pain and Disability Index (SPADI), Patient Specific Functional Score, Euro Qol 5D-3L, Short Form 36, global rating of change and impairment measures. Analysis was by intention-to-treat. A total of 73 participants were randomized to treatment and data were available for the analysis of 36 in the PUFA supplement group versus 33 in the placebo. Both groups improved over the time course of the study. Plasma concentrations of EPA and DHA increased in the long-chain omega-3 PUFA supplemented group but not in the placebo, providing evidence that the participants took the supplements. There was no evidence of added benefit from long-chain omega-3 PUFA supplementation for the primary outcome change in OSS -0.23 (95% CI 3.89, 3.43) or in SPADI -1.68 (-12.64, 9.28) at two months. There was some evidence to suggest that SPADI was lower in the treatment group at three months. There was no difference in outcomes between groups at 12 months. Twelve participants undertook semi-structured face to face interviews to explore experiences, barriers, motivators and enablers to supplement use and exercise. The predominant enablers to exercise were found to be the perceived benefit from the exercises and extended follow up, with barriers being lack of suitable equipment and pain. The enablers to supplement taking were found to be the perceived benefit of the supplements and a systematic pill taking routine. Barriers were the size, taste and quantity of supplements, remembering to take them, and, lack of perceived benefit.

Wounding is a major clinical problem. Calcium is a common secondary messenger eliciting a range of responses through spatial/temporal regulation. In keratinocytes, intracellular calcium (Ca2+i) plays a key role in growth and differentiation. An epidermal calcium gradient exists in skin which is disrupted post-wounding and wounding of monolayer human keratinocytes results in an intercellular calcium wave. Additionally, regulation of the calcium wave is known to be dependent on purinergic signalling and/or gap-junctions. However, their relative contribution in mediating the calcium flux post-wounding in primary human keratinocytes have not been well characterised. Furthermore, the importance of this calcium flux to downstream transcriptional and functional responses is not fully understood. To address this knowledge gap, the effect of store-operated calcium entry (SOCE), gap-junctions and extracellular ATP was investigated using primary human keratinocyte monolayers loaded with the calcium dye Fluo4-AM. Scratch wounding was performed in 0.06mM and 1.2mM [Ca2+]o and images captured using confocal microscopy. Calcium add-back experiments and the use of specific inhibitors were used to characterise the calcium responses. Results showed that, as expected, wounding caused an increase in Ca2+i within cells at the wound edge, which then travelled back as a wave. Both gap-junction inhibition (18αGA) and the removal of extracellular ATP (hexokinase) reduced Ca2+i flux and prevented the spread of the calcium wave following wounding. Nuclear factor of activated T-cells (NFAT) is a transcription factor activated by an increase in Ca2+i and known to be involved in keratinocyte differentiation. NFAT firefly luciferase was used to investigate activation in response to wounding. Results show NFAT transcriptional activation post-wounding in 1.2mM but not 0.06mM [Ca2+]o. Additionally, 18αGA, and the SOCE inhibitor GSK-7975A significantly reduced wound-induced NFAT activation. Perhaps surprisingly, hexokinase had no effect. Finally, the functional consequence of these signalling pathways were investigated using scratch wound migration assays. Wounds closed at a faster rate when wounding was performed in 1.2mM [Ca2+]o compared to 0.06mM. Manipulation of all three signalling pathways inhibited wound closure. However, gap-junction blockade completely prevented wound closure. Together these data indicate that, whilst purinergic and gap-junction signalling regulate the Ca2+i flux and wave post-wounding, there is a dominant effect of gap-junctions in the activation of NFAT and cell migration.

This thesis examined hardiness, coping and stress-related growth (SRG) following sport injury. Study 1 examined the relationship between hardiness and SRG. The data were analyzed using Pearson product-moment correlations and Preacher’s and Hayes’s (2008) bootstrapping procedure. Findings revealed a significant positive relationship between hardiness and perceived SRG, and two strategies were found to mediate this relationship: emotional support and positive reframing. That is, the reason why athletes higher in hardiness had higher SRG scores was because they reported greater use of their social support for emotional reasons (e.g., moral support, sympathy or understanding) and were able to construe their injury in positive terms. Despite these significant findings and their important contribution to research, the data is limited due to its quantitative nature. Therefore, Study 2 aimed to enhance the interpretability and meaningfulness of the findings from Study 1. Specifically, Study 2 aimed to explain how injured athletes high in hardiness promoted stress-related growth (SRG) and why athletes low in hardiness were less likely to derive such benefits. Semi-structured interviews were conducted and transcribed, which were then analyzed and displayed using composite sequence analysis. Findings revealed that athletes high in hardiness experienced SRG through four mechanisms: (a) emotional outlet, (b) positive reframing, (c) positive affect, and (d) investing in resources. In contrast, athletes low in hardiness had no emotional outlet, which led to a number of sub-optimal outcomes. This study observed the importance of emotional disclosure during one’s recovery from injury. Informed by the findings from Study 1 and 2, Study 3a and 3b aimed to evaluate an emotional disclosure intervention with injured athletes low in hardiness. The intervention was for four weeks, and included a four week follow-up and a three month social validation interview. The intervention consistent of three groups: a written-disclosure group (WD Group), verbal-disclosure group (VD Group), and the Control Group (C Group). The quantitative data were analyzed using repeated measures AVOVA and MAVOVA, and the qualitative data were analyzed using thematic analysis. Findings revealed the VD Group experienced significantly more SRG than the control group. This finding was explained from the VD Group fully disclosing their thoughts and feelings, and having sufficient time to restructure their stories. Both the WD and VD Groups recalled writing and talking to be a cathartic process; however, they did not report as many desirable outcomes as the VD Group. In conclusion, this thesis has achieved its purpose, and has made a significant contribution to research in a number of ways. From a theoretical perspective, it supported and extended a number of theories and models including the Wiese-Bjornstal et al.’s (1998) integrated model of responses to sport injury, the Organismic Valuing Theory (Joseph & Linley, 2005), and broaden-and-build-theory of positive emotions (Fredrickson, 2013). This thesis also had an empirical impact, as it integrated two lines of which have examined hardiness or SRG following injury, extended research by directly examining the relationship between hardiness and SRG and the coping strategies that mediate this relationship. This thesis not only supported previous hardiness research but also supported and extended research within the growth and sport injury literature, as well as disclosure research within in a sporting and non-sporting context. Finally, from an applied perspective, it emphasizes that practitioners who work with injured athletes may not only have an important role in preventing and/or repairing the negative consequences of injury, but also in terms of enabling them to experience SRG.

The signature weapon of the conflicts in Iraq and Afghanistan has been the roadside bomb (anti-vehicle mine, AV) or improvised explosive device (IED). Detonation of the explosive under a vehicle leads to rapid deflection of the vehicle floor, transmitting a very short duration, high amplitude load into the foot and ankle complex in contact with it. To date, there has been no clinical data on the pattern of lower limb injury or clinical outcome following an under-vehicle explosion. Using contemporary battlefield casualty data of UK service personnel injured in Iraq and Afghanistan, 63 casualties (89 injured limbs) were identified with lower leg injuries from explosion. Fifty percent of casualties sustained multi-segmental injuries to the foot and ankle complex and 29% required amputation, with 74% having on-going clinical problems at mean 33 months follow-up. Sub-group analysis showed that casualties standing at the time of explosion had significantly greater injury severity and poorer clinical outcome. In order to investigate the effect of limb orientation on injury severity, both finite element analysis and experimental approach was used. A traumatic injury simulator (Anti-vehicle mine underbelly blast injury simulator, AnUBIS) was developed to recreate the impulse witnessed in explosions within a laboratory setting. Initial experiments with instrumented cadaveric limbs impacted at 8.2-8.6 m/s demonstrated that for the same impulse the standing cadaveric limb sustained significantly severe injuries compared to the seated position. The data presented in this thesis has shown that lower limb injuries from AV mine explosions are associated with a poor clinical outcome. Primary prevention remains key in reducing the injury burden to the combat soldier. The development of realistic traumatic injury simulations allows for better understanding of the underlying injury mechanics, thereby focusing future research in injury mitigation and the development of improved lower limb test surrogates.