Imperial College London

Anthony M J Bull FREng

Faculty of EngineeringDepartment of Bioengineering

Professor of Musculoskeletal Mechanics
 
 
 
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Contact

 

+44 (0)20 7594 5186a.bull Website

 
 
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Location

 

Uren 514aSir Michael Uren HubWhite City Campus

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Summary

 

Publications

Publication Type
Year
to

360 results found

Ashworth E, Baxter D, Gibb I, Wilson M, Bull Aet al., 2024, Injuries in fatalities of dismounted blast: identification of four mechanisms of head and spine injury., J Neurotrauma

Blast is the most common injury mechanism in conflicts of this century due to the widespread use of explosives, confirmed by recent conflicts such as in Ukraine. Data from conflicts in the last century such as Northern Ireland, the Falklands and Vietnam up to present day, show between 16 and 21% of personnel suffered a traumatic brain injury. Typical features of fatal brain injury to those outside of a vehicle (hereafter referred to as dismounted) due to blast include the presence of haemorrhagic brain injury alongside skull fractures rather than isolated penetrating injuries more typical of traditional ballistic head injuries. The heterogeneity of dismounted blast has meant that analysis from databases is limited and therefore a detailed look at the radiological aspects of injury is needed to understand the mechanism and pathology of dismounted blast brain injury. The aim of this study was to identify the head and spinal injuries in fatalities due to dismounted blast. All UK military fatalities from dismounted blast who suffered a head injury from 2007-2013 in the Iraq and Afghanistan conflicts were identified retrospectively. Post-mortem computerised tomography images (CTPMs) were interrogated for injuries to the head, neck and spine. All injuries were documented and classified using a radiology brain injury classification tool. Chi-squared and Fisher's Exact tests were used investigate correlations between injuries, along with odds ratios for determining direction of correlation. The correlations were clustered. There were 71 fatalities from dismounted blast with an associated head injury with a CTPM or initial CT available for analysis. The results showed the heterogeneity of injury from dismounted blast but also some potential identifiable injury constellations. These were: • intracranial haemorrhage • deep haemorrhage • spinal injury • facial injury These identified injury patterns can now be investigated to consider injury mechanisms and s

Journal article

Dyball D, Bennett AN, Schofield S, Cullinan P, Boos CJ, Bull AM, Stevelink SA, Fear NTet al., 2024, The underlying mechanisms by which Post-Traumatic Growth is associated with cardiovascular health in male UK military personnel: The ADVANCE cohort study., J Health Psychol

Post-Traumatic Growth (PTG) is associated with good cardiovascular health, but the mechanisms of this are poorly understood. This cross-sectional analysis assessed whether factors of PTG (Appreciation of Life (AOL), New Possibilities (NP), Personal Strength (PS), Relating to Others (RTO) and Spiritual Change (SC)) are associated with cardiovascular health in a cohort of 1006 male UK military personnel (median age 34). The findings suggest AOL, PS and RTO are associated with better cardiovascular health through cardiometabolic effects (lower levels of triglycerides, and total cholesterol) and haemodynamic functioning (lower diastolic blood pressure), but not inflammation. However, NP and SC were associated with poorer cardiovascular health through cardiometabolic effects (lower levels of high-density lipoproteins and higher levels of total cholesterol) and AOL had a non-linear association with low-density lipoproteins. These findings suggest that the relationship between PTG and cardiovascular functioning is complex and in need of further scrutiny.

Journal article

Vollert J, Kumar A, Coady EC, Cullinan P, Dyball D, Fear NT, Gan Z, Miller EF, Sprinckmoller S, Schofield S, Bennett A, Bull AMJ, Boos CJ, Rice ASC, Kemp HI, ADVANCE Studyet al., 2024, Pain after combat injury in male UK military personnel deployed to Afghanistan., Br J Anaesth

BACKGROUND: Chronic pain after injury poses a serious health burden. As a result of advances in medical technology, ever more military personnel survive severe combat injuries, but long-term pain outcomes are unknown. We aimed to assess rates of pain in a representative sample of UK military personnel with and without combat injuries. METHODS: We used data from the ADVANCE cohort study (ISRCTN57285353). Individuals deployed as UK armed forces to Afghanistan were recruited to include those with physical combat injuries, and a frequency-matched uninjured comparison group. Participants completed self-reported questionnaires, including 'overall' pain intensity and self-assessment of post-traumatic stress disorder, anxiety, and depression. RESULTS: A total of 579 participants with combat injury, including 161 with amputations, and 565 uninjured participants were included in the analysis (median 8 yr since injury/deployment). Frequency of moderate or severe pain was 18% (n=202), and was higher in the injured group (n=140, 24%) compared with the uninjured group (n=62, 11%, relative risk: 1.1, 95% confidence interval [CI]: 1.0-1.2, P<0.001), and lower in the amputation injury subgroup (n=31, 19%) compared with the non-amputation injury subgroup (n=109, 26%, relative risk: 0.9, 95% CI: 0.9-1.0, P=0.034). Presence of at least moderate pain was associated with higher rates of post-traumatic stress (RR: 3.7, 95% CI: 2.7-5.0), anxiety (RR: 3.2, 95% CI: 2.4-4.3), and depression (RR: 3.4, 95% CI: 2.7-4.5) after accounting for injury. CONCLUSION: Combat injury, but not amputation, was associated with a higher frequency of moderate to severe pain intensity in this cohort, and pain was associated with adverse mental health outcomes.

Journal article

Maqsood R, Schofield S, Bennett AN, Khattab A, Clark C, Bull AMJ, Fear NT, Boos CJet al., 2024, The influence of physical and mental health mediators on the relationship between combat-related traumatic injury and ultra-short-term heart rate variability in a U.K. military cohort: a structural equation modeling approach, Military Medicine: international journal of AMSUS, Vol: 189, Pages: e758-e765, ISSN: 0026-4075

Introduction:Combat-related traumatic injury (CRTI) adversely affects heart rate variability (HRV). The mediating effect of mental and physical health factors on the relationship between CRTI, its severity and HRV has not been previously studied and investigated.Materials and Methods:A cross-sectional mediation analysis of the ArmeD SerVices TrAuma and RehabilitatioN OutComE (ADVANCE) prospective cohort study was performed. The sample consisted of injured and uninjured British male servicemen who were frequency-matched based on their age, rank, role-in-theater, and deployment to Afghanistan (2003-2014). CRTI and injury severity (the New Injury Severity Scores [NISS] [NISS < 25 and NISS ≥ 25]) were included as exposure variables. HRV was quantified using the root mean square of successive differences (RMSSD) obtained using pulse waveform analysis. Depression and anxiety mediators were quantified using the Patient Health Questionnaire and Generalized Anxiety Disorder, respectively. Body mass index and the 6-minute walk test (6MWT) represented physical health measures. Two mediation pathways between exposure and outcome variables were examined in comparison with the uninjured group using structural equation modeling.Results:Of 862 servicemen, 428 were injured and 434 were uninjured with the mean age at assessment of 33.9 ± 5.4 (range 23-59) years. Structural equation modeling revealed that depression, anxiety, and body mass index did not significantly mediate the relationship between injury/injury severity and RMSSD. However, the 6MWT significantly mediated the relationship between CRTI and RMSSD (27% mediation). The indirect effect of 6MWT on the relationship between injury severity (NISS ≥ 25 vs. uninjured) and RMSSD was −0.06 (95% CI: −0.12, −0.00, P < .05).Conclusions:The findings suggest that greater physical function may improve HRV following CRTI. Longitudi

Journal article

Toderita D, Favier C, Henson D, Vardakastani V, Sherman K, Bennett AN, Bull Aet al., 2023, Hip joint and muscle loading for persons with bilateral transfemoral/through-knee amputations: biomechanical differences between full-length articulated and foreshortened non-articulated prostheses, Journal of NeuroEngineering and Rehabilitation, Vol: 20, ISSN: 1743-0003

Background:Currently, there is little available in-depth analysis of the biomechanical effect of different prostheses on the musculoskeletal system function and residual limb internal loading for persons with bilateral transfemoral/through-knee amputations (BTF). Commercially available prostheses for BTF include full-length articulated prostheses (microprocessor-controlled prosthetic knees with dynamic response prosthetic feet) and foreshortened non-articulated stubby prostheses. This study aims to assess and compare the BTF musculoskeletal function and loading during gait with these two types of prostheses.Methods:Gait data were collected from four male traumatic military BTF and four able-bodied (AB) matched controls using a 10-camera motion capture system with two force plates. BTF completed level-ground walking trials with full-length articulated and foreshortened non-articulated stubby prostheses. Inverse kinematics, inverse dynamics and musculoskeletal modelling simulations were conducted.Results:Full-length articulated prostheses introduced larger stride length (by 0.5 m) and walking speed (by 0.3 m/s) than stubbies. BTF with articulated prostheses showed larger peak hip extension angles (by 10.1°), flexion moment (by 1.0 Nm/kg) and second peak hip contact force (by 3.8 bodyweight) than stubbies. There was no difference in the hip joint loading profile between BTF with stubbies and AB for one gait cycle. Full-length articulated prostheses introduced higher hip flexor muscle force impulse than stubbies.Conclusions:Compared to stubbies, BTF with full-length articulated prostheses can achieve similar activity levels to persons without limb loss, but this may introduce detrimental muscle and hip joint loading, which may lead to reduced muscular endurance and joint degeneration. This study provides beneficial guidance in making informed decisions for prosthesis choice.

Journal article

Widanage KND, De Silva MJ, Lalitharatne T, Bull A, Gopura RARCet al., 2023, Developments in circular external fixators: a review, Injury, Vol: 54, ISSN: 0020-1383

Circular external fixators (CEFs) are successfully used in orthopedics owing to their highly favorable stiffness characteristics which promote distraction osteogenesis. Although there are different designs of external fixators, how these features produce optimal biomechanics through structural and component designs is not well known. Therefore, the aim of this study was to conduct a review on CEFs following the PRISMA statement. A search for relevant research articles was performed on Scopus and PubMed databases providing the related keywords. Furthermore, a patent search was conducted on the Google Patent database. 126 records were found to be eligible for the review. Different designs of CEFs were summarized and tabulated based on their specific features. A bibliometric analysis was also performed on the eligible research papers. Based on the findings, the developments of CEFs in terms of materials, automation, adjustment methods, component designs, wire-clamping, and performance evaluation have been extensively discussed. The trends of the CEF design and future directions are also discussed in this review. Significant research gaps include a lack of consideration towards ease of assembly, effective wire-clamping methods, and CEFs embedded with online patient-monitoring systems, among others. An apparent lack of research interest from low-middle and low-income countries was also identified.

Journal article

Boos CJ, Haling U, Schofield S, Cullinan P, Bull AMJ, Fear NT, Bennett AN, ADVANCE Studyet al., 2023, Relationship between combat-related traumatic injury and its severity to predicted cardiovascular disease risk: ADVANCE cohort study., BMC Cardiovasc Disord, Vol: 23

BACKGROUND: This study investigated the relationship between combat-related traumatic injury (CRTI) and its severity and predicted cardiovascular disease (CVD) risk. MATERIAL AND METHODS: This was an analysis of comparative 10-year predicted CVD risk (myocardial infarction, stroke or CVD-death) using the QRISK®3 scoring-system among adults recruited into the Armed Services Trauma Rehabilitation Outcome (ADVANCE) cohort study. Participants with CRTI were compared to uninjured servicemen frequency-matched by age, sex, rank, deployment (Afghanistan 2003-2014) and role. Injury severity was quantified using the New Injury Severity Score (NISS). RESULTS: One thousand one hundred forty four adult combat veterans were recruited, consisting of 579 injured (161 amputees) and 565 uninjured men of similar age ethnicity and time from deployment/injury. Significant mental illness (8.5% vs 4.4%; p = 0.006) and erectile dysfunction (11.6% vs 5.8%; p < 0.001) was more common, body mass index (28.1 ± 3.9 vs 27.4 ± 3.4 kg/m2; p = 0.001) higher and systolic blood pressure variability (median [IQR]) (1.7 [1.2-3.0] vs 2.1 [1.2-3.5] mmHg; p = 0.008) lower among the injured versus uninjured respectively. The relative risk (RR) of predicted CVD (versus the population expected risk) was higher (RR:1.67 [IQR 1.16-2.48]) among the injured amputees versus the injured non-amputees (RR:1.60 [1.13-2.43]) and uninjured groups (RR:1.52 [1.12-2.34]; overall p = 0.015). After adjustment for confounders CRTI, worsening injury severity (higher NISS, blast and traumatic amputation) were independently associated with QRISK®3 scores. CONCLUSION: CRTI and its worsening severity were independently associated with increased predicted 10-year CVD risk.

Journal article

Dimitrov H, Bull AMJ, Farina D, 2023, High-density EMG, IMU, kinetic, and kinematic open-source data for comprehensive locomotion activities., Sci Data, Vol: 10

Novel sensor technology enables new insights in the neuromechanics of human locomotion that were previously not possible. Here, we provide a dataset of high-density surface electromyography (HDsEMG) and high-resolution inertial measurement unit (IMU) signals, along with motion capture and force data for the lower limb of 10 healthy adults during multiple locomotion modes. The participants performed level-ground and slope walking, as well as stairs ascent/descent, side stepping gait, and stand-to-walk and sit-to-stand-to-walk, at multiple walking speeds. These data can be used for the development and validation of locomotion mode recognition and control algorithms for prosthetics, exoskeletons, and bipedal robots, and for motor control investigations.

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Boos CJ, Schofield S, Bull AMJ, Fear NT, Cullinan P, Bennett ANet al., 2023, The relationship between combat-related traumatic amputation and subclinical cardiovascular risk, International Journal of Cardiology, Vol: 390, Pages: 1-7, ISSN: 0167-5273

BackgroundThe relationship between acute combat-related traumatic injury (CRTI) to coronary flow reserve (CFR) and subclinical cardiovascular risk have not been examined and was the primary aim of this study.Methods and resultsUK combat veterans from the ADVANCE cohort study (UK-Afghanistan War 2003–14) with traumatic limb amputations were compared to injured non-amputees and to a group of uninjured veterans from the same conflict. Subclinical cardiovascular risk measures included fasted blood atherogenic index of plasma (AIP), triglyceride-glucose index (TyG; insulin resistance), the neutrophil-lymphocyte ratio (NLR) and high-sensitivity C-reactive protein (hs-CRP; vascular inflammation), body mass index (BMI) and visceral fat volume (dual-energy X-ray absorptiometry) and 6-min walk distance (6MWD; physical performance). The subendocardial viability ratio (SEVR), to estimate CFR, was calculated using arterial pulse waveform analysis (Vicorder device). In total 1144 adult male combat veterans were investigated, comprising 579 injured (161 amputees, 418 non-amputees) and 565 uninjured men. AIP, TyG, NLR, hs-CRP, BMI, total body fat and visceral fat volume were significantly higher and the SEVR and 6MWD significantly lower in the amputees versus the injured-non-amputees and uninjured groups. The SEVR was lowest in those with above knee and multiple limb amputations. CRTI (ExpB 0.96; 95% CI 0.94–0.98: p < 0.0001) and amputation (ExpB 0.94: 95% CI 0.91–0.97: p < 0.0001) were independently associated with lower SEVR after adjusting for age, rank, ethnicity and time from injury.ConclusionCRTI, traumatic amputation and its worsening physical deficit are associated with lower coronary flow reserve and heightened subclinical cardiovascular risk.

Journal article

Liu S, Amiri P, McGregor A, Bull Aet al., 2023, Bilateral asymmetry in knee and hip musculoskeletal loading during stair ascending/descending in individuals with unilateral mild to moderate medial knee osteoarthritis, Annals of Biomedical Engineering, Vol: 51, Pages: 2490-2503, ISSN: 0090-6964

Most cases of unilateral knee osteoarthritis (OA) progress to bilateral OA within 10 years. Biomechanical asymmetries have been implicated in contralateral OA development; however, gait analysis alone does not consistently detect asymmetries in OA patient gait. Stair ambulation is a more demanding activity that may be more suited to reveal between-leg asymmetries in OA patients. The objective of this study was to investigate the between-leg biomechanical differences in patients with unilateral mild-to-moderate knee OA. Sixteen unilateral mild-to-moderate medial knee OA patients and 16 healthy individuals underwent kinematic and kinetic analysis of stair ascent and descent. Stair ascent produced higher loading and muscle forces in the unaffected limb compared to the OA limb, and stair descent produced lower loading on the OA limb compared to healthy subjects. These biomechanical differences were apparent in the ankle, knee, and hip joints. The implications of these findings are that OA patients rely more heavily on their unaffected sides than the affected side in stair ascent, a strategy that may be detrimental to the unaffected joint health. The reduction in affected limb loading in stair descent is thought to be related to minimizing pain.

Journal article

Behan F, Bull A, Bennett A, 2023, Developing an exercise intervention to improve bone mineral density in traumatic amputees: protocol for a Delphi study, BMJ Open, Vol: 13, ISSN: 2044-6055

Introduction:Lower limb amputation results in reduced bone mineral density (BMD) on the amputated side. Exercise interventions have proven effective in improving BMD. However, such interventions have not been attempted in an amputee population. Exercises designed for people with intact limbs may not be suitable for amputees, due to joint loss and the mechanical interface between the exercise equipment and the femoral neck being mediated through a socket. Therefore, prior to intervention implementation, it would be prudent to leverage biomechanical knowledge and clinical expertise, alongside scientific evidence in related fields, to assist in intervention development. The objective of this study is to elicit expert opinion and gain consensus to define specific exercise prescription parameters to minimise/recover BMD loss in amputees.Methods and analysis:The Delphi technique will be used to obtain consensus among international experts, this will be conducted remotely as an e-Delphi process. 10-15 experts from ≥ 2 continents, and ≥ 5 countries will be identified through published research or clinical expertise and asked to provide digital informed consent. Round 1 will consist of participants being asked to rate their level of agreement with statements related to exercise prescription to improve amputee BMD using a 5-point Likert scale. Agreement will be deemed as ≥ 3 on the Likert scale. Open feedback will be allowed in round 1 and any statement which less than 50% of the experts agree with, will be excluded. Round 2 will repeat remaining statements with the addition of any input from round 1 feedback. Round 3 will allow participants to reflect on their round 2 responses considering statistical representation of group opinion and whether they wish to alter any of their responses accordingly. Statements reaching agreement rates of 70% or above among the experts will be deemed to reach a consensus and will be implemented in a future exercise interventional tria

Journal article

McMenemy L, Behan FP, Kaufmann J, Cain D, Bennett AN, Boos CJ, Fear NT, Cullinan P, Bull AMJ, Phillips ATM, McGregor AHet al., 2023, Association between combat-related traumatic injury and skeletal health: bone mineral density loss is localized and correlates with altered loading in amputees: the Armed Services Trauma Rehabilitation Outcome (ADVANCE) Study, Journal of Bone and Mineral Research, Vol: 38, Pages: 1227-1233, ISSN: 0884-0431

The association between combat-related traumatic injury (CRTI) and bone health is uncertain. A disproportionate number of lower limb amputees from the Iraq and Afghanistan conflicts are diagnosed with osteopenia/osteoporosis, increasing lifetime risk of fragility fracture and challenging traditional osteoporosis treatment paradigms. The aim of this study is to test the hypotheses that CRTI results in a systemic reduction in bone mineral density (BMD) and that active traumatic lower limb amputees have localized BMD reduction, which is more prominent with higher level amputations. This is a cross-sectional analysis of the first phase of a cohort study comprising 575 male adult UK military personnel with CRTI (UK-Afghanistan War 2003 to 2014; including 153 lower limb amputees) who were frequency-matched to 562 uninjured men by age, service, rank, regiment, deployment period, and role-in-theatre. BMD was assessed using dual-energy X-ray absorptiometry (DXA) scanning of the hips and lumbar spine. Femoral neck BMD was lower in the CRTI than the uninjured group (T-score -0.08 versus -0.42 p = .000). Subgroup analysis revealed this reduction was significant only at the femoral neck of the amputated limb of amputees (p = 0.000), where the reduction was greater for above knee amputees than below knee amputees (p < 0.001). There were no differences in spine BMD or activity levels between amputees and controls. Changes in bone health in CRTI appear to be mechanically driven rather than systemic and are only evident in those with lower limb amputation. This may arise from altered joint and muscle loading creating a reduced mechanical stimulus to the femur resulting in localized unloading osteopenia. This suggests that interventions to stimulate bone may provide an effective management strategy. © 2023 Crown copyright and The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Soci

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Xu L, Yu X, Favier CD, Igah I, Nguyen T-T, Macdonald W, Bull AMJet al., 2023, Development of an experimental method for well-controlled blast induced traumatic limb fracture in rats, Defence Technology, ISSN: 2214-9147

Heterotopic ossification (HO) is a consequence of traumatic bone and tissue damage, which occurs in 65% of military casualties with blast-associated amputations. However, the mechanisms behind blast-induced HO remain unclear. Animal models are used to study blast-induced HO, but developing such models is challenging, particularly in how to use a pure blast wave (primary blast) to induce limb fracture that then requires an amputation. Several studies, including our recent study, have developed platforms to induce limb fractures in rats with blast loading or a mixture of blast and impact loading. However, these models are limited by the survivability of the animal and repeatability of the model. In this study, we developed an improved platform, aiming to improve the animal's survivability and injury repeatability as well as focusing on primary blast only. The platform exposed only one limb of the rat to a blast wave while providing proper protection to the rest of the rat's body. We obtained very consistent fracture outcome in the tibia (location and pattern) in cadaveric rats with a large range of size and weight. Importantly, the rats did not obviously move during the test, where movement is a potential cause of uncontrolled injury. We further conducted parametric studies by varying the features of the design of the platform. These factors, such as how the limb is fixed and how the cavity through which the limb is placed is sealed, significantly affect the resulting injury. This platform and test setups enable well-controlled limb fracture induced directly by pure blast wave, which is the fundamental step towards a complete in vivo animal model for blast-induced HO induced by primary blast alone, excluding secondary and tertiary blast injury. In addition, the platform design and the findings presented here, particularly regarding the proper protection of the animal, have implications for future studies investigating localized blast injuries, such as blast induced br

Journal article

Milandri G, Wijesinghe PCI, Munidasa D, Pathmanathan C, Saeidi M, Bull AMJ, Silva Pet al., 2023, Clinical trial of a low-cost external fixator for global surgery use, International Orthopaedics, Vol: 47, Pages: 1663-1669, ISSN: 0341-2695

PURPOSE: A low-cost modular external fixator for the lower limb has been developed for global surgery use. The purpose of this study is to assess outcome measures in the first clinical use of the device. METHODS: A prospective cohort study was conducted with patients recruited in two trauma hospitals. Initial clinical procedure data were collected, and patients were followed up every two weeks until 12 weeks or definitive fixation. Follow-up assessed infection, stability, and radiographic outcomes. In addition, patient-reported outcomes and surgeons' feedback on device usability were collected by questionnaires. RESULTS: The external fixator was used on 17 patients. Ten were mono-lateral, five were joint spanning, and two were delta configuration. One patient had a pin site infection at 12-week follow-up. All were stable when tested mechanically and using radiographic assessment, and 53% were converted to definitive fixation. CONCLUSION: The low-cost external fixator developed is appropriate for use in global surgery trauma centres with good clinical outcomes. PROSPECTIVE TRIAL REGISTRATION NUMBER AND DATE: SLCTR/2021/025 (06 Sep 2021).

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Patil A, Kulkarni K, Xie S, Bull AMJ, Jones GGet al., 2023, The accuracy of statistical shape models in predicting bone shape: a systematic review, International Journal of Medical Robotics and Computer Assisted Surgery, Vol: 19, Pages: 1-13, ISSN: 1478-5951

BackgroundThis systematic review aims to ascertain how accurately 3D models can be predicted from two-dimensional (2D) imaging utilising statistical shape modelling.MethodsA systematic search of published literature was conducted in September 2022. All papers which assessed the accuracy of 3D models predicted from 2D imaging utilising statistical shape models and which validated the models against the ground truth were eligible.Results2127 papers were screened and a total of 34 studies were included for final data extraction. The best overall achievable accuracy was 0.45 mm (root mean square error) and 0.16 mm (average error).ConclusionStatistical shape modelling can predict detailed 3D anatomical models from minimal 2D imaging. Future studies should report the intended application domain of the model, the level of accuracy required, the underlying demographics of subjects, and the method in which accuracy was calculated, with root mean square error recommended if appropriate.

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Sargent W, Mahoney P, Clasper J, Bull A, Reavley P, Gibb Iet al., 2023, Understanding the burden of injury in children from conflict: an analysis of radiological imaging from a Role 3 hospital in Afghanistan in 2011, BMJ MILITARY HEALTH, ISSN: 2633-3767

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Benton A, Amiri P, Henson DP, Sivapuratharasu B, McGregor AH, Bull Aet al., 2023, Characterization of muscle recruitment during gait of bilateral transfemoral and through-knee persons with limb loss, Frontiers in Bioengineering and Biotechnology, Vol: 11, Pages: 1-10, ISSN: 2296-4185

Introduction: Due to loss in musculoskeletal capacity, there is an increased burden on the residual limbs of bilateral transfemoral and through-knee persons with limb loss. This reduced capacity is associated with an increased cost of walking that is detrimental to functionality. Compensatory gait strategies are adopted by this population. However, how these strategies relate to specific muscle recruitment is not known. The primary aim of this study is to characterize muscle recruitment during gait of this population. The secondary aim is to assess whether the measured kinematics can be actuated when the endurance of specific muscles is reduced and if this is the case, which alternative muscles facilitate this.Methods: 3D gait data and high-resolution magnetic resonance images were acquired from six bilateral transfemoral and through-knee persons with limb loss. Subject-specific anatomical muscle models were developed for each participant, and a validated musculoskeletal model was used to quantify muscle forces in two conditions: during normal gait (baseline) and when muscles, which were identified as functioning above a “healthy” level at baseline, have a reduced magnitude of maximum force capacity (reduced endurance simulation). To test the hypothesis that there are differences in muscle forces between the baseline trials and the simulations with reduced muscular endurance, a Bonferroni corrected two-way ANOVA with repeated measures was completed between the two states.Results: The baseline analysis showed that the hip flexors experience relatively high muscle activations during gait. The reduced endurance simulation found two scenarios. First, for 5 out of the 12 simulations, the baseline kinematics could not be reproduced with the reduced muscular capacity. Second, for 7 out of 12 cases where the baseline kinematics were achieved, this was possible with compensatory increased activation of some muscles with similar functions (p ≤ 0.003).Discussion

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Farina D, Vujaklija I, Branemark R, Bull AMJ, Dietl H, Graimann B, Hargrove LJ, Hoffmann K-P, Huang HH, Ingvarsson T, Janusson HB, Kristjansson K, Kuiken T, Micera S, Stieglitz T, Sturma A, Tyler D, Weir RFF, Aszmann OCet al., 2023, Toward higher-performance bionic limbs for wider clinical use, Nature Biomedical Engineering, Vol: 7, Pages: 473-485, ISSN: 2157-846X

Most prosthetic limbs can autonomously move with dexterity, yet they are not perceived by the user as belonging to their own body. Robotic limbs can convey information about the environment with higher precision than biological limbs, but their actual performance is substantially limited by current technologies for the interfacing of the robotic devices with the body and for transferring motor and sensory information bidirectionally between the prosthesis and the user. In this Perspective, we argue that direct skeletal attachment of bionic devices via osseointegration, the amplification of neural signals by targeted muscle innervation, improved prosthesis control via implanted muscle sensors and advanced algorithms, and the provision of sensory feedback by means of electrodes implanted in peripheral nerves, should all be leveraged towards the creation of a new generation of high-performance bionic limbs. These technologies have been clinically tested in humans, and alongside mechanical redesigns and adequate rehabilitation training should facilitate the wider clinical use of bionic limbs.

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Maqsood R, Schofield S, Bennett AN, Bull AM, Fear NT, Cullinan P, Khattab A, Boos CJ, ADVANCE studyet al., 2023, Relationship between combat-related traumatic injury and ultrashort term heart rate variability in a UK military cohort: findings from the ADVANCE study, BMJ Military Health, Pages: 1-6, ISSN: 2633-3767

INTRODUCTION: Combat-related traumatic injury (CRTI) has been linked to an increased cardiovascular disease (CVD) risk. The long-term impact of CRTI on heart rate variability (HRV)-a robust CVD risk marker-has not been explored. This study investigated the relationship between CRTI, the mechanism of injury and injury severity on HRV. METHODS: This was an analysis of baseline data from the ArmeD SerVices TrAuma and RehabilitatioN OutComE (ADVANCE) prospective cohort study. The sample consisted of UK servicemen with CRTI sustained during deployment (Afghanistan, 2003-2014) and an uninjured comparison group who were frequency matched to the injured group based on age, rank, deployment period and role in theatre. Root mean square of successive differences (RMSSD) was measured as a measure of ultrashort term HRV via <16 s continuous recording of the femoral arterial pulse waveform signal (Vicorder). Other measures included injury severity (New Injury Severity Scores (NISS)) and injury mechanism. RESULTS: Overall, 862 participants aged 33.9±5.4 years were included, of whom 428 (49.6%) were injured and 434 (50.3%) were uninjured. The mean time from injury/deployment to assessment was 7.91±2.05 years. The median (IQR) NISS for those injured was 12 (6-27) with blast being the predominant injury mechanism (76.8%). The median (IQR) RMSSD was significantly lower in the injured versus the uninjured (39.47 ms (27.77-59.77) vs 46.22 ms (31.14-67.84), p<0.001). Using multiple linear regression (adjusting for age, rank, ethnicity and time from injury), geometric mean ratio (GMR) was reported. CRTI was associated with a 13% lower RMSSD versus the uninjured group (GMR 0.87, 95% CI 0.80-0.94, p<0.001). A higher injury severity (NISS ≥25) (GMR 0.78, 95% CI 0.69-0.89, p<0.001) and blast injury (GMR 0.86, 95% CI 0.79-0.93, p<0.001) were also independently associated with lower RMSSD. CONCLUSION: These results suggest an inverse association between CR

Journal article

Nolte D, Xie S, Bull A, 2023, 3D shape reconstruction of the femur from planar X-ray images using statistical shape and appearance models, BioMedical Engineering OnLine, Vol: 22, Pages: 1-14, ISSN: 1475-925X

Major trauma is a condition that can result in severe bone damage. Customised orthopaedic reconstruction allows for limb salvage surgery and helps to restore joint alignment. For the best possible outcome three dimensional (3D) medical imaging is necessary, but its availability and access, especially in developing countries, can be challenging. In this study, 3D bone shapes of the femur reconstructed from planar radiographs representing bone defects were evaluated for use in orthopaedic surgery. Statistical shape and appearance models generated from 40 cadaveric X-ray computed tomography (CT) images were used to reconstruct 3D bone shapes. The reconstruction simulated bone defects of between 0% and 50% of the whole bone, and the prediction accuracy using anterior–posterior (AP) and anterior–posterior/medial–lateral (AP/ML) X-rays were compared. As error metrics for the comparison, measures evaluating the distance between contour lines of the projections as well as a measure comparing similarities in image intensities were used. The results were evaluated using the root-mean-square distance for surface error as well as differences in commonly used anatomical measures, including bow, femoral neck, diaphyseal–condylar and version angles between reconstructed surfaces from the shape model and the intact shape reconstructed from the CT image. The reconstructions had average surface errors between 1.59 and 3.59 mm with reconstructions using the contour error metric from the AP/ML directions being the most accurate. Predictions of bow and femoral neck angles were well below the clinical threshold accuracy of 3°, diaphyseal–condylar angles were around the threshold of 3° and only version angle predictions of between 5.3° and 9.3° were above the clinical threshold, but below the range reported in clinical practice using computer navigation (i.e., 17° internal to 15° external rotation). This study shows that the reconstruc

Journal article

Graham NSN, Blissitt G, Zimmerman K, Friedland D, Dumas M-E, Coady E, Heslegrave A, Zetterberg H, Escott-Price V, Schofield S, Fear NT, Boos C, Bull AMJ, Cullinan P, Bennett A, Sharp DJ, ADVANCE Studyet al., 2023, ADVANCE-TBI study protocol: traumatic brain injury outcomes in UK military personnel serving in Afghanistan between 2003 and 2014 - a longitudinal cohort study, BMJ Open, Vol: 13, ISSN: 2044-6055

INTRODUCTION: Outcomes of traumatic brain injury (TBI) are highly variable, with cognitive and psychiatric problems often present in survivors, including an increased dementia risk in the long term. Military personnel are at an increased occupational risk of TBI, with high rates of complex polytrauma including TBI characterising the UK campaign in Afghanistan. The ArmeD SerVices TrAuma and RehabilitatioN OutComE (ADVANCE)-TBI substudy will describe the patterns, associations and long-term outcomes of TBI in the established ADVANCE cohort. METHODS AND ANALYSIS: The ADVANCE cohort comprises 579 military personnel exposed to major battlefield trauma requiring medical evacuation, and 566 matched military personnel without major trauma. TBI exposure has been captured at baseline using a standardised interview and registry data, and will be refined at first follow-up visit with the Ohio State Method TBI interview (a National Institute of Neurological Disorders and Stroke TBI common data element). Participants will undergo blood sampling, MRI and detailed neuropsychological assessment longitudinally as part of their follow-up visits every 3-5 years over a 20-year period. Biomarkers of injury, neuroinflammation and degeneration will be quantified in blood, and polygenic risk scores calculated for neurodegeneration. Age-matched healthy volunteers will be recruited as controls for MRI analyses. We will describe TBI exposure across the cohort, and consider any relationship with advanced biomarkers of injury and clinical outcomes including cognitive performance, neuropsychiatric symptom burden and function. The influence of genotype will be assessed. This research will explore the relationship between military head injury exposure and long-term outcomes, providing insights into underlying disease mechanisms and informing prevention interventions. ETHICS AND DISSEMINATION: The ADVANCE-TBI substudy has received a favourable opinion from the Ministry of Defence Research Eth

Journal article

Ding Z, Henson D, Sivapuratharasu B, McGregor A, Bull Aet al., 2023, The effect of muscle atrophy in people with unilateral transtibial amputation for three activities: gait alone does not tell the whole story, Journal of Biomechanics, Vol: 149, Pages: 1-10, ISSN: 0021-9290

Amputation imposes significant challenges in locomotion to millions of people with limb loss worldwide. The decline in the use of the residual limb results in muscle atrophy that affects musculoskeletal dynamics in daily activities. The aim of this study was to quantify the lower limb muscle volume discrepancy based on magnetic resonance (MR) imaging and to combine this with motion analysis and musculoskeletal modelling to quantify the effects in the dynamics of key activities of daily living. Eight male participants with traumatic unilateral transtibial amputation were recruited who were at least six months after receiving their definitive prostheses. The muscle volume discrepancies were found to be largest at the knee extensors (35 %, p = 0.008), followed by the hip abductors (17 %, p = 0.008). Daily activities (level walking, standing up from a chair and ascending one step) were measured in a motion analysis laboratory and muscle and joint forces quantified using a detailed musculoskeletal model for people with unilateral transtibial amputation which was calibrated in terms of the muscle volume discrepancies post-amputation at a subject-specific level. Knee extensor muscle forces were lower at the residual limb than the intact limb for all activities (p ≤ 0.008); residual limb muscle forces of the hip abductors (p ≤ 0.031) and adductors (p ≤ 0.031) were lower for standing-up and ascending one step. While the reduced knee extensor force has been reported by other studies, our results suggest a new biomechanically-based mitigation strategy to improve functional mobility, which could be achieved through strengthening of the hip abd/adductor muscles.

Journal article

Dyball D, Bennett AN, Schofield S, Cullinan P, Boos CJ, Bull AMJ, Stevelink SAM, Fear NTet al., 2023, The underlying mechanisms by which PTSD symptoms are associated with cardiovascular heath in male UK military personnel: The ADVANCE cohort study, JOURNAL OF PSYCHIATRIC RESEARCH, Vol: 159, Pages: 87-96, ISSN: 0022-3956

Journal article

Rebelo EA, Grigoriadis G, Carpanen D, Bull AMJ, Masouros Set al., 2023, Stature and mitigation systems affect the risk of leg injury in vehicles attacked under the body by explosive devices, Frontiers in Bioengineering and Biotechnology, Vol: 11, Pages: 1-5, ISSN: 2296-4185

A finite-element (FE) model, previously validated for underbody blast (UBB) loading, was used here to study the effect of stature and of mitigation systems on injury risk to the leg. A range of potential UBB loadings was simulated. The risk of injury to the leg was calculated when no protection was present, when a combat boot (Meindl Desert Fox) was worn, and when a floor mat (IMPAXXTM), which can be laid on the floor of a vehicle, was added. The risk of injury calculated indicates that the floor mat provided a statistically significant reduction in the risk of a major calcaneal injury for peak impact speeds below 17.5 m/s when compared with the scenarios in which the floor mat was not present. The risk of injury to the leg was also calculated for a shorter and a taller stature compared to that of the nominal, 50th percentile male anthropometry; shorter and taller statures were constructed by scaling the length of the tibia of the nominal stature. The results showed that there is a higher risk of leg injury associated with the short stature compared to the nominal and tall statures, whereas the leg-injury risk between nominal and tall statures was statistically similar. These findings provide evidence that the combat boot and the floor mat tested here have an attenuating effect, albeit limited to a range of possible UBB loads. The effect of stature on injury has implications on how vehicle design caters for all potential anthropometries and indeed gender, as women, on average, are shorter than men. The results from the computational simulations here complement laboratory and field experimental models of UBB, and so they contribute to the improvement of UBB safety technology and strategy.

Journal article

Campos-Pires R, Dickinson R, 2023, Modelling Blast Brain Injury, Blast Injury Science and Engineering: A Guide for Clinicians and Researchers, Editors: Bull, Clasper, Mahoney, Publisher: Springer Cham, Pages: 315-331, ISBN: 978-3-031-10354-4

The consequences of blast traumatic braininjury (blast-TBI) in humans are largely determinedby the characteristics of the traumainsult and, within certain limits, the individualresponses to the lesions inflicted (Maas et al.,Lancet Neurol. 2008;7:728–41). In blast-TBI,the mechanisms of brain vulnerability to thedetonation of an explosive device are not completelyunderstood. They most likely resultfrom a combination of the different physicalaspects of the blast phenomenon, specificallyextreme pressure oscillations (blast overpressurewave), projectile penetrating fragmentsand acceleration–deceleration forces, creatinga spectrum of brain injury that ranges frommild to severe blast-TBI(Hicks et al., JTrauma. 2010; 68:1257-63).The pathophysiologyof penetrating and inertially drivenblast-TBI has been extensively investigatedfor many years. However, the brain damagecaused by blast overpressure is much lessunderstood and is unique to this type of TBI(Chen et al., J Neurotrauma. 2009; 26:861–76). Indeed, there continues to be debate abouthow the pressure wave is transmitted andreflected through the brain and how it causescellular damage (Nakagawa et al., JNeurotrauma. 2011; 28:1101–19). No singlemodel can mimic the clinical and mechanicalcomplexity resulting from a real-lifeblast-TBI (Chen et al., J Neurotrauma. 2009;26:861–76). The different models, non-biological(in silico or surrogate physical) andbiological (ex vivo, in vitro or in vivo), tend tocomplement each other.

Book chapter

Bull AMJ, Clasper J, Mahoney PF, 2023, Preface, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: ix-vii

Journal article

Arora H, Bull AMJ, 2023, In Vitro Models of Primary Blast: Organ Models, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: 309-314, ISBN: 9783031103544

Primary blast injury research at the organ level aims to identify local injury mechanisms caused by shock wave loading. In vitro and ex vivo organ level models of blast bridge the gap between length scales (e.g. from cellular to whole body) and provide suitable platforms for studying the effects of blast on isolated systems prior to any further study, e.g. potentially in vivo or for evaluating efficacy of armour systems. Specific damage mechanisms have been studied using a combination of exposure to real explosives, lab-based blast simulators, shock tube devices and other bespoke test arrangements to deliver shocks to isolated tissues (Chap. 30). The effects of magnitude and duration of primary loading have demonstrated their relative degradative effects on isolated organs such as the brain, lung and whole bones. As methods of organ preservation are advancing and injury diagnostics are improving in other disciplines, so other organ models of primary blast such as for the kidney and eye are now being developed.

Book chapter

Kazezian Z, Bull AMJ, 2023, Pathological Cascades Leading to Heterotopic Ossification Following Blast Injury, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: 245-251, ISBN: 9783031103544

Heterotopic ossification (HO) is the process of de novo bone formation in non-osseous tissues and is common following blast-induced traumatic amputations. Inflammatory cytokines as well as mechanical loading play a key role in the initiation and the progression of the disease and therefore the downstream biomarkers under specific signal transduction pathways which trigger the formation of the ectopic bone in the tissues surrounding the site of injury are key. However, the current published knowledge, summarised here, shows that there is a lack of understanding of the exact signalling pathways leading to HO, thus hampering the design of specific therapeutics. Also, there are no in vivo preclinical models that replicate the full scenario of blast, fracture and amputation, experienced in conflict blast injuries. These models are required to fully dissect the triggered signalling pathways. Therefore, this gap in the literature urgently needs addressing. Replicating the full effect of the blast in preclinical models will enable a better understanding of the mechanisms of blast-induced HO development and enable the design of a specific therapeutic to suppress the formation of ectopic bone.

Book chapter

Bull AMJ, 2023, Biomechanics of Blast Rehabilitation, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: 499-506, ISBN: 9783031103544

Blast injuries can result in significant musculoskeletal deficits due to neurological or anatomical damage. This chapter focuses on the biomechanical effects of blast injury and its impact on the ability of an individual to achieve desired tasks. Motion is driven by muscles that have small moment arms relative to the centres of the joints that are moving, causing very high muscle and joint reaction forces relative to the external load. A small disruption to the muscular anatomy can dramatically reduce the ability of the person to achieve the task, and so rehabilitation seeks to optimise the way the task is performed in terms of the path of motion as well as how the muscles activate to achieve the tasks. Motion and muscle activation can be analysed using biomechanical models. These models have been applied to reducing osteoarthritis in blast-induced traumatic amputees, optimising prosthetic parameters to reduce fatigue, and changing gait patterns to reduce muscle fatigue and lower the loads on joints.

Book chapter

Ramette M, Bull AMJ, 2023, In-Silico Modelling of Blast-Induced Heterotopic Ossification, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: 285-294, ISBN: 9783031103544

Computational modelling of how ectopic bone forms following blast injury can predict both the location and severity of the aberrant bone. As a loading-mediated process, this modelling uses the principle of Wolff’s Law combined with mechanobiological theory to investigate the effect of loading during treatment and rehabilitation. Small changes to the loading can significantly change the volume and type of ectopic bone formed and opens the way for future mechanical therapies.

Book chapter

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