The influence of wear paths produced by hip replacement patients during normal walking on wear rates

Variation in wear paths is known to greatly affect wear rates in vitro, with multidirectional paths producing much greater wear than unidirectional paths. This study investigated the relationship between multidirectional motion at the hip joint, as measured by aspect ratio, sliding distance, and wear rate for 164 hip replacements. Kinematic input from three-dimensional gait analysis was used to determine the wear paths. Activity cycles were determined for a subgroup of 100 patients using a pedometer study, and the relationship between annual sliding distance and wear rate was analyzed. Poor correlations were found between both aspect ratio and sliding distance and wear rate for the larger group and between annual sliding distance and wear rate for the subgroup. However, patients who experienced a wear rate <0.08 mm/year showed a strong positive correlation between the combination of sliding distance, activity levels, and aspect ratio and wear rate (adjusted r2?=?55.4%). This group may represent those patients who experience conditions that most closely match those that prevail in simulator and laboratory tests. Although the shape of wear paths, their sliding distance, and the number of articulation cycles at the hip joint affect wear rates in simulator studies, this relationship was not seen in this clinical study. Other factors such as lubrication, loading conditions and roughness of the femoral head may influence the wear rate.

Self-generated expressions of residual complaints following brain injury

Following brain injury there is often a prolonged period of deteriorating psychological condition, despite neurological stability or improvement. This is presumably consequent to the remission of anosognosia and the realisation of permanently worsened status. This change is hypothesised to be directed partially by the socially mediated processes which play a role in generating self-awareness and which here direct the reconstruction of the self as a permanently injured person. However, before we can understand this process of redevelopment, we need an unbiassed technique to monitor self-awareness. Semi-structured interviews were conducted with 30 individuals with long-standing brain injuries to capture their spontaneous complaints and their level of insight into the implications of their difficulties. The focus was on what the participants said in their own words, and the extent to which self-knowledge of difficulties was spontaneously salient to the participants. Their responses were subjected to content analysis. Most participants were able to say that they had brain injuries and physical difficulties, many mentioned memory and attentional problems and a few made references to a variety of emotional disturbances. Content analysis of data from unbiassed interviews can reveal the extent to which people with brain injuries know about their difficulties. Social constructionist accounts of self-awareness and recovery are supported.

Recovery from brain injury: Finding the missing bits of the puzzle

Background: One basic problem found during rehabilitation is that people with brain injuries lack awareness of their difficulties. Research into this phenomenon has often disregarded the voices of those affected by the trauma and do not give an insider's perspective on the process through which a person with a brain injury develops awareness of their difficulties.

A comparative study of nursing attitudes towards young male survivors of brain injury: A questionnaire survey.

Background The attitudes members of the nursing profession hold towards survivors of brain injury may impact on the level of help, and degree of involvement they are willing to have. Given that the manner in which an individual receives their brain injury has been shown to impact on public prejudices, the importance of exploring nursing attitudes to this vulnerable group, and the subsequent impact this may have on the caring role, requires investigation. Objective To investigate the attitudes held by members of the nursing profession towards young male survivors of brain injury whose behaviour either contributed, or did not contribute, to their injury. Design Independent groups design. Setting and participants Ninety trainee and sixty-nine qualified nurses respectively drawn from a university in the south west of England and the emergency, orthopaedic and paediatric Departments of the Royal Devon and Exeter Hospital, UK. Methods Participants were randomly assigned to one of four fictional brain injury scenarios. A young male character was portrayed as sustaining a brain injury as a result of either an aneurysm, or through drug taking, with their behaviour being either a contributory or non-contributory factor. On reading these, participants were asked to complete the prejudicial evaluation scale, the social interaction scale and the helping behaviour scale. Results Analysis of variance showed that qualified nurses held more prejudicial attitudes than student nurses towards survivors of brain injury. Mean scores indicated that individuals seen as contributing towards their injury were likely to experience more prejudice (blame total = 42.35 vs. no blame total = 38.34), less social interaction (blame total = 37.54 vs. no blame total = 41.10), and less helping behaviour (blame total = 21.49 vs. no blame total = 22.34) by both groups. Conclusions Qualified nurses should be mindful of the impact their attitudes and judgements of survivors of brain injury may have on the subsequent care they provide. Greater emphasis on the effects of negative attitudes on patient interactions during training may provide nurses with the understanding to recognise and avoid challenges to their caring role in the future.

Correlation of synovial fluid cytokine levels with histological and clinical parameters of primary and revision total hip and total knee replacements

We retrieved synovial tissue and fluid samples from patients undergoing primary total hip replacement (THR) (n 15), revision of aseptically loose THR (n 12), primary total knee replacement (TKR) (n 13) and revision of aseptically loose TKR (n 6). Several histological parameters were assessed on a relative scale of 1-4. Primary TJRs were clinically evaluated for degree of osteoarthrosis. Revision TJRs were assessed for migration of the implant, gross loosening and the degree of radiolucency. Cytokine levels in synovial fluid were determined with ELISA.

Nasal potential difference to detect Na+ channel dysfunction in acute lung injury

Pulmonary fluid clearance is regulated by the active transport of Na+ and Cl- through respiratory epithelial ion channels. Ion channel dysfunction contributes to the pathogenesis of various pulmonary fluid disorders including high-altitude pulmonary edema (HAPE) and neonatal respiratory distress syndrome (RDS). Nasal potential difference (NPD) measurement allows an in vivo investigation of the functionality of these channels. This technique has been used for the diagnosis of cystic fibrosis, the archetypal respiratory ion channel disorder, for over a quarter of a century. NPD measurements in HAPE and RDS suggest constitutive and acquired dysfunction of respiratory epithelial Na+ channels. Acute lung injury (ALI) is characterized by pulmonary edema due to alveolar epithelial-interstitial-endothelial injury. NPD measurement may enable identification of critically ill ALI patients with a susceptible phenotype of dysfunctional respiratory Na+ channels and allow targeted therapy toward Na+ channel function. text of link

Cement-in-cement revision hip arthroplasty: an analysis of clinical and biomechanical literature

Introduction The number of revision hip arthroplasties is increasing but several aspects of this procedure could be improved. One method of reducing intra-operative complications is the cement-in-cement technique. This procedure entails cementing a smaller femoral prosthesis into the existing stable cement mantle. The aim of this systematic review is to provide a concise overview of the existing historical, operative, biomechanical and clinical literature on the cement-in-cement construct.

Experimental investigation of negative pressure intrusion techniques of acetabular cementation in total hip arthroplasty

The main mode of failure of the acetabular component in total hip arthroplasty is aseptic loosening. Successive generations of cementation techniques have evolved to alleviate this problem.

Cement mantle fatigue failure in total hip replacement: Experimental and computational testing

One possible loosening mechanism of the femoral component in total hip replacement is fatigue cracking of the cement mantle. A computational method capable of simulating this process may therefore be a useful tool in the preclinical evaluation of prospective implants. In this study, we investigated the ability of a computational method to predict fatigue cracking in experimental models of the implanted femur construct. Experimental specimens were fabricated such that cement mantle visualisation was possible throughout the test. Two different implant surface finishes were considered: grit blasted and polished. Loading was applied to represent level gait for two million cycles. Computational (finite element) models were generated to the same geometry as the experimental specimens, with residual stress and porosity simulated in the cement mantle. Cement fatigue and creep were modelled over a simulated two million cycles. For the polished stem surface finish, the predicted fracture locations in the finite element models closely matched those on the experimental specimens, and the recorded stem displacements were also comparable. For the grit blasted stem surface finish, no cement mantle fractures were predicted by the computational method, which was again in agreement with the experimental results. It was concluded that the computational method was capable of predicting cement mantle fracture and subsequent stem displacement for the structure considered. (C) 2006 Elsevier Ltd. All rights reserved.