The thermal degradation behaviour of a polyurethane foam, synthesised from TDI and a polyether polyol, is reported. The thermal degradation behaviour of this material was evaluated by a combination of thermogravimetric analysis (TGA) and thermal volatilisation analysis (TVA). The results demonstrated that the thermal degradation is a complex process which consists of competing mechanisms which yield an array of degradation products. The TVA results revealed that the degradation occurs in two steps, with the initial step corresponding to degradation of the urethane linkages by two competing mechanisms. The first mechanism, proposed to be the predominant mechanism, involves simple depolymerisation of the urethane bond to yield TDI and polyol. A second, competing mechanism is proposed to occur which involves dissociation of the urethane linkages to yield DAT, CO2 and alkene-terminated polyol chains. The second degradation step has been shown to involve degradation of the polyol which was regenerated in the first degradation step. This is proposed to occur by random radical chain scission of the polyol to yield propene, formaldehyde, acetaldehyde, C3H6O isomers and high molar mass polyol chain fragments of various structures. Isothermal TVA studies have revealed that this occurs as low as 250 degrees C under vacuum but does not become significant until temperatures greater than 300 degrees C
Patients with ankylosing spondylitis (AS) are vulnerable to cervical spine fractures. Long-standing pain may mask the symptoms of the fracture. Radiological imaging of the cervical spine may fail to identify the fracture due to the distorted anatomy, ossified ligaments and artefacts leading to delay in diagnosis and increased risk of neurological complications. The objectives are to identify the incidence and risk factors for delay in presentation of cervical spine fractures in patients with AS. Retrospective case series study of all patients with AS and cervical spine fracture admitted over a 12-year period at Queen Elizabeth National Spinal Injuries Unit, Scotland. Results show that total of 32 patients reviewed with AS and cervical spine fractures. In 19 patients (59.4%), a fracture was not identified on plain radiographs. Only five patients (15.6%) presented immediately after the injury. Of the 15 patients (46.9%) who were initially neurologically intact, three patients had neurological deterioration before admission. Cervical spine fractures in patients with long-standing AS are common and usually under evaluated. Early diagnosis with appropriate radiological investigations may prevent the possible long-term neurological cord damage.
Individual in-depth interviews with eight people who had experienced a total spinal cord injury were conducted, focussing on the experience of living with a spinal cord injury. The interviews were transcribed verbatim and were analysed for recurrent themes using Interpretative Phenomenological Analysis (IPA). Here we present three inter-related recurrent themes: 'Loss of control'; 'Loss of independence' and 'Loss of identity'. Participants reported an ongoing sense of loss, characterised largely by a diminishing sense of personal control. This loss of personal control manifested itself in incontinence, emotion and loss of movement. Helplessness and embarrassment were common responses. A loss of independence was associated with incontinence but also with a loss of spontaneity. A loss of identity ensued and participants reported feeling 'invisible'. The findings are discussed in relation to both extant spinal cord literature and chronic health literature. Recommendations for future research are suggested.
Rehabilitation of walking is an essential element in the treatment of incomplete spinal cord injured (SCI) patients. During the early post injury period, patients find it challenging to practice upright walking. Simulating stepping movements in a supine posture may be easier and promote earlier rehabilitation. A robotic orthotic device for early intervention in spinal cord injury that does not require the patient to be in an upright posture has been modelled. The model comprises a two-bar mechanical system that is configured and powered to provide limb kinematics that approximate normal overground walking. The modelling work has been based on gait analysis performed on healthy subjects walking at 50 per cent, 75 per cent, and 100 per cent of normal cadence. Simulated angles of hip, knee, and ankle joints show a comparable range of motion (ROM) to the experimental walking data measured in healthy subjects. The model provides operating parameters for a prospective recumbent gait orthosis that could be used in early walking rehabilitation of incomplete SCI patients.
We aimed to develop a better understanding and method of rating the success or failure of low back surgery by studying 185 patients prospectively. Identical pre-operative and postoperative assessment by an independent observer included pain, disability, physical impairment, psychological distress and illness behaviour. Outcome was assessed by the patient, by the observer and by return to work. There was 96% follow-up at two years. Correlation co-efficients varied considerably between the various measures of outcome, both patient and observer appearing to base their assessment mainly on postoperative status rather than on any change produced by surgery. The observer was influenced most by postoperative pain, disability and physical impairment. Patients were influenced most by residual physical impairment, type of surgery and proportional change in disability. Return to work was moderately influenced by postoperative disability and to a larger extent by social and work-related factors. We developed a simple formula to judge overall success or failure which accurately reproduced the combined assessment of patient and observer. If surgical audit is to be meaningful it must be based on an improved understanding of how the outcome of surgery should be assessed.
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