This work was undertaken to assess the feasibility of using cortical signals to control motor prostheses in paraplegics. Signals would be required which could be quickly and reliably detected, and remain unchanged after spinal transection. For this purposa arrays of small recording eleotrodes ware placed over the precentral gyrus beneath the dura meter. In baboons, such chronically implanted eleotrodes (0.5 mm diemeter) recorded a wide range of electrical activity. Only when a frequency band 80 - 250 Hz was selected could signals be detected in the electrocorticogram which were movement-related, consistently stable, and seen to precede specific movements of the contralateral limbs.

Wrist joint prostheses have developed from simple silicone joint spacers to the current state of the art where design philosophy now follows that of large joint replacement. A variety of shortcomings identified in existing designs through their clinical use led to the development of a new wrist joint prosthesis being designed. A combination of disciplines yields the necessary data and tools to develop the optimum solution to replicating the anatomical rotational centres of the healthy wrist whilst at the same time satisfying the requirements of stability, effective implantation and wear characteristics. The key tool in drawing conclusions from the articulating surfaces selected in the design proposals is Finite Element Analysis. The use of an implicit, nonlinear static contact analysis model developed and solved using MSC MARC software was used to examine the behaviour of the implant models' Ultra High Molecular Weight Polyethylene component over a large range of motion and under a compressive load. The anticipated displacements and loads caused by performing daily living tasks fall comfortably within the range of motion specified for the analyses. This, coupled with repeated analysis of the model for small geometrical alterations enabled an optimum model to be selected. The information from these analyses was used directly in making decisions on the design of the prosthesis in conjunction with cadaveric trials. The initial cadaveric trial validated the primary geometrical features of the design regarding centres of rotation and stem location and identified clear areas for design refinement. The second trial fully validated the design decisions taken. Following the analytical work on the new design, and the completion of the cadaveric trials, a comparative analysis was carried out with competing designs to further validate the design. The results of this show that the new design is competitive in terms of demonstrating low stress concentrations over a practical range of motion, and that it also has excellent stability. Beyond these features, the new implant design also facilitates secure implantation, in conjunction with a range of sizes likely to accommodate the greatest range of patient anatomical variation.

This thesis investigates the mechanics behind Achilles tendinopathies and their respective treatments using a musculoskeletal modelling approach. Specifically, the eccentric heel-drop exercise used to treat Achilles tendinosis and orthotic heel wedges used to treat Achilles tendonitis were investigated, as the mechanics which drive tendon healing are not currently understood, but are believed to work by directly altering the mechanical loading of the Achilles tendon. An inverse dynamics model of the lower limb including the hip, knee ankle and MTP joints was developed to include a musculoskeletal foot and ankle model. An existing muscle geometry dataset was used, but a new algorithm to account for soft tissue and bony constraints at the ankle to ensure physiological musculo-tendon paths around the foot and ankle was developed. Optical motion, forceplate and instrumented pressure insole data was used to derive independent 3D ground reaction vectors necessary for the data inputs for each of the two foot segments modelled. In addition to the moments of the hip and knee, foot and ankle muscle forces and ankle joint reaction forces were also estimated. A cohort of 19 healthy individuals performed the eccentric heel-drop exercise used to treat Achilles tendinosis and walked on a level and up and down an inclined (10°) surface barefoot and in running shoes with and without prefabricated orthotic heel wedges used to treat Achilles tendonitis. Clinical questions regarding changes in lower limb mechanics due to variants of the eccentric heel-drop exercise and orthotic heel wedges were considered as well as model sensitivity to foot models and sources of centre of pressure (CoP) data. CoP data source and number of foot segments modelled did not consistently change the model outputs, with greater or worse similarity between sources depending on the specific phase of stance considered. An example of this are the reduced knee and hip extension moments and increased ankle dorsiflexion moments at heel-strike, but consistent peak ankle joint reaction and Achilles tendon forces due to different CoP inputs. Across all walking conditions, heel wedges were found to have minimal impact on Achilles tendon force, but had a significant impact on knee moments and secondary plantarflexors such as Tibialis Posterior and the toe flexor muscles. The ability of heel wedges to reduce Achilles tendon load during walking was not supported by this thesis. Key observations regarding the eccentric heel-drop exercise were the reductions in peak Achilles tendon force achieved when performing the exercise in running shoes compared to barefoot and with a flexed compared to extended knee. Given the increased difficulty in performing the flexed knee exercise, this questioned the efficacy of the flexed knee version of the task and possible changes to the rehabilitation protocol, incorporating the effect of shoes on peak Achilles tendon force were suggested.

Low back pain is a major health and socio-economic problem in Western countries. It is important therefore to learn more about its cause for prevention. To date, research has focused upon identifying risk factors that play a role in recurrent episodes of low back pain to further knowledge for secondary prevention. It can be argued however that it is more important to prevent the very first episode of low back pain from occurring by learning about the primary causative mechanisms. The aim of this thesis therefore is to advance theories about the possible causes of the first ever episode of low back pain for primary prevention. The qualitative, in-depth interview study presented in this thesis approaches the study of the first ever episode of low back pain, its antecedents and causal attributions from the perspective of subtle realism. Thirty participants presenting to NHS hospital physiotherapy and medical outpatient clinics were recruited for interview. The interview data were transcribed verbatim, and the data managed and analysed using Framework, a method developed by the National Centre for Social Research. The study’s findings advance knowledge about the possible role of psychological distress involving loss, anger, low mood and social withdrawal, and ‘pushing worries to the back of the mind’ in the genesis of non-specific symptoms including low back pain. If confirmed by further research, preventive strategies may need to address the perception that low back pain is not a stress-related condition and gender differences in the conceptualisation of stress. An area for new research is a perceived disposition to physical activity since childhood and a lifestyle described as active before the first ever episode of low back pain. Lay definitions of ‘real’ low back pain may assist the design of this research.

Spinal manipulation is a commonly sought therapy for neck pain. The present work examined sagittal plane cervical inter-vertebral kinematics in patients and healthy volunteers to explore whether motion is different in patients with neck pain, if manipulation is associated with changing cervical kinematics, and if changes are related to patient-reported outcomes. A standardised quantitative fluoroscopy (QF) image acquisition protocol for the cervical spine was developed and tested. A model of a cervical segment with a rigidly fitted digital inclinometer was rotated in the sagittal plane whilst being fluoroscopically imaged and QF results were compared for accuracy to that of the inclinometer. QF imaging sequences from ten subjects were analysed twice, six weeks apart, to assess repeatability. Finally, 30 patients and 30 age/gender-matched healthy volunteers had two cervical spine QF assessments four weeks apart. Only patients received spinal manipulation and completed patient-reported outcome measures (PROMs). Kinematic variables of interest included IV-RoM, segmental hypo-mobility, paradoxical motion, instantaneous axis of rotation (IAR) location, and laxity/attainment rate. The acquisition protocol allowed for imaging sequences to be achieved in a manner acceptable to participants. QF was found to be accurate to 0.5° for rotational range of motion. Intra- and inter-observer repeatability studies revealed substantial agreement and reliability for the QF measurement of C1 to C6 rotational motion (largest standard error of measurement (SEM) = 1.14°, lowest intra-class correlation coefficient (ICC) = 0.895) but not for IAR location (largest SEM = 7.66mm, lowest ICC = -0.080). Agreement and reliability were moderate-substantial for laxity/attainment rate (largest SEM = 0.04, lowest ICC = 0.70). There were no significant differences at baseline between patients and healthy volunteers in IV-RoM, or in the number of hypo-mobile, paradoxical or lax motion segments. Spinal manipulation was weakly associated with IV-RoM increases above the minimum detectable change calculated from healthy volunteers, in a dose response manner (Rho = 0.39 (95% CI: 0.014 to 0.663) p = 0.04). While the majority (87%) of patients reported clinically significant reductions in pain and disability, changes in IV-RoM were not correlated with any of the PROMs measured.

Background Peritoneal infection that follows surgery is associated with SIRS and the development of multi-organ dysfunction. It has a high mortality. The dynamics of leucocyte trafficking into the peritoneal cavity and the expression of cytokines in response to either endotoxin or abdominal surgery will effect the development of both local and systemic inflammation. Firstly the leucocyte trafficking in response to intraperitoneal LPS (lipopolysaccharide) is compared to an abdominal incision. Then, using the expression of TNFα on the cell membrane as a marker of pro-inflammatory status, this expression is described in animals undergoing surgery followed by a 'second hit' of ip LPS. Finally the ability of these trafficked cells to trigger SIRS leading to pathophysiological effects in the lungs was assessed. Methods C57/B6 mice were exposed to either an intra-peritoneal dose of 20ng LPS or abdominal surgery and the leucocytes identified and counted in both blood and peritoneal lavage fluid by flow cytometry. A two-hit model was devised, abdominal surgery the primary hit and 24 hours later ip LPS the second hit. The expression of TNFα was measured with flow cytometry. Using two intravenous dyes a lung permeability index was created comparing mice primed by surgery and those just receiving LPS. The data was analysed using student t-test and one-way ANOVA as appropriate. Results: The time course of migration was different for the various leucocyte sub-populations in response to both LPS and surgery. There was a significant increase in the expression of membrane bound TNFα on monocytes and macrophages in the two-hit model than with surgery or LPS alone. There was a trend to greater lung permeability in the two-hit group. Conclusions Leucocytes migrate to the peritoneal cavity after surgery and are primed to respond vigorously to a subsequent dose of LPS. This may have effects on lung permeability.

Low back pain represents a significant financial burden to society. The major costs are associated with chronic back pain which often arises as a result of intervertebral disc degeneration. Discs lie between the vertebrae and are separated fi'om them by a cartilaginous and bony endplate. The endplate is vital for intervertebral disc health because of its role in load-transfer and disc nutrition. Consequently, changes to the endplate due to ageing or injury may adversely affect the disc and contribute to varying forms of degeneration.

Introduction/Background: Outcomes assessment in orthopaedics has advanced over the last decade. There are various different methods that can be used in a clinical setting to assess function and pain. During a clinical consultation, a simple, quick and restricted history, examination and review of investigations can be undertaken. Aim: I wished to ascertain whether function improved as a result of knee or hip joint replacement, and which of the commonly used existing methods of assessing function are of most value in this context. Methods: To achieve this aim, I recruited a broad spectrum of patients about to undergo primary or revision surgery for hip (n=42) or knee (n=51) joint disease. The study design was an observational cohort study, with data collection points pre-operatively and at 3 months post-operatively. Results: Most participants had less pain and better function 3 months after surgery than pre-operatively. However, the mean scores obscured the fact that several participants showed no improvement or worsening on some of the scores. Participants with the worst functional scores at baseline were most likely to improve. Performance tests showed less overall improvement than self-assessment measures. Overall walking times correlate well with all the other scores, with the exception of the Short Form-12 mental component score and American Knee Society Knee Score. However, in hip participants those with the best Harris Hip Scores did not have the best walking times, or the best Western Ontario and McMaster Arthritis Index or best Short Form-12 scores. Flexion beyond 90 degrees did not correlate with functional scores at the hip. Both inter and intra-rater reliability findings were good for both the Harris Hip Score and American Knee society score. Conclusions: Differences are identified in the outcome between different health status instruments commonly used in assessing function by self report questionnaires, surgeon based and performance based assessments. More research is needed to identify either the best method or more likely different instruments to identify important specific domains after hip and knee joint surgery.

Background: Currently in the UK, posterior and lateral surgical approaches are routinely performed for hip replacement, with medial parapatellar and subvastus approaches used for knee replacement. To ensure best patient care, surgeons need robust evidence to inform t he choice of surgical approach. Aims: To compare outcomes after different surgical approaches in hip and knee re placement, I conducted a series of systematic reviews and meta-analyses. Methods: Using Cochrane methods, I conducted literature searches to identify randomised controlled trials comparing approaches for hip and knee replacement. Functional outcomes and adverse events were compared in meta-analyses. Results: Six studies including 517 hip replacements showed a lower risk of Trendelenburg gait (Odds Ratio 0.31L but no functional advantage following the posterior approach compared with the lateral approach. Sixteen studies including lA98 hip replacements compared posterior and minimally invasive posterior approaches to the hip. Clinically insignificant improvements in functional outcome, operating time, hospital stay and blood loss were observed following the minimally invasive posterior approach. Adverse events were similar between approaches. Eighteen studies including 1,711 knee replacements compared subvastus and medial parapatellar approaches. The Knee Society score was improved by 7.7 points (95%CI 5.25, 10.05) at six weeks post-surgery, and 2.8 points (95%CI 0.83,4.85) at one year in the subvastus group compared with the medial para patellar group. Adverse events were similar between approaches. Conclusions: In hip replacement, the minimally invasive posterior approach appears equivalent to the standard posterior approach for functional outcome and adverse events whilst limiting incision length. In knee replacement, small clinically insignificant benefits in functional outcome, acute pain, and time to regain active straight leg raise were associated with the subvastus approach. There were no differences in the rates of adverse events. My research identifies the need for a high quality randomised trial comparing posterior and lateral approaches in hip replacement.

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