1,721,242 research outputs found
Assessing early postoperative recovery following lower limb joint replacement
Get PDFImproving perioperative recovery is critical to enhance patient care, ensure timely discharge from the patient, clinician and hospital perspective and improve short and long-term outcomes after surgery.
A systematic review was performed examining tools for early post-operative recovery after elective lower limb joint replacement. It showed that no fully-validated, patient-reported tools existed. Currently used measures included pain scores, opioid usage, length of stay and surgical satisfaction.
In order to address this need, a patient-reported outcome measure (PROM) and change measure for use in the first six weeks following surgery have been developed. A five-phased, best practice, iterative approach was used.
Planning Phase - Qualitative interviews (n=22) were performed with orthopaedic healthcare professionals, ascertaining if and how clinicians would use such a PROM. These helped determine the views of potential users, and guide structure and layout.
Phase One - Qualitative patient-interviews (n=30) from the day of surgery to nine weeks postoperatively were completed. Analysis of these interviews identified important patient-reported factors in early recovery.
Phase Two - The factors provided from Phase One interviews were used to find questionnaire themes. Items were then generated and pilot questionnaires developed. Items were tested and refined in the context of cognitive debrief interviews (n=34) for potential inclusion in the final tools.
Phase Three - Final testing of questionnaire properties with item reduction (n=168). The Oxford Arthroplasty Early Recovery Score (OARS) is a 14-item PROM measuring health status at the time of testing. The Oxford Arthroplasty Early Change Score (OACS) is a 14-item measure to assess change.
Phase Four - Validation: The OARS and OACS were administered to consecutive patients (n=155) in an independent cohort. Validity and reliability were assessed. Psychometric testing showed positive results, good validity and sensitivity to change.
The OARS and OACS were then utilised in a pilot study to assess the feasibility of day case treatment. Inpatient (n=29) and day-case (n=26) unicompartmental knee arthroplasty (UKA) patients completed the two measures, and the results confirmed that day case treatment and discharge is a valid option.
The work completed in this thesis will now enable these newly developed scores to be used to define and assess an optimal-recovery protocol for lower limb joint replacement
The investigation and management of metal-on-metal hip arthroplasty patients
Get PDFMany metal-on-metal hip arthroplasties (MoMHAs) were implanted worldwide in the form of hip resurfacing arthroplasty (HRA) and total hip arthroplasty. These devices experienced unexpectedly high short-term failure rates, with many revisions performed for adverse reactions to metal debris (ARMD) and pseudotumour (a specific type of ARMD). To identify problems early, worldwide regulatory authorities recommend most MoMHA patients require regular follow-up. However these recommendations are not evidence-based and are very costly. The broad aims of this thesis were to determine the clinical impact of pseudotumour, and to develop evidence-based guidance for the investigation and management of MoMHA patients.
A prospective single centre cohort of 1,429 HRAs identified pseudotumour as the commonest indication for revision surgery. The overall 15 year pseudotumour revision rate was high at 14.0%. Young females had the highest risk of pseudotumour revision, whilst males with Birmingham Hip Resurfacing (BHR) implants had the lowest risk.
Two large prospective cohort studies investigated the role of blood metal ions during follow-up. Patients with BHR implants (n=494) who had blood metal ions below newly devised thresholds were at low risk of ARMD (cobalt: 2.15 μg/l for unilateral BHRs; maximum cobalt or chromium: 5.52 μg/l for bilateral BHRs). Current fixed regulatory authority thresholds missed more patients with ARMD compared with the new thresholds. These findings were subsequently validated in 416 BHR patients at two external European centres.
Three observational studies investigated the role of hip imaging during follow-up. Radiographic factors predictive of HRAs with a pseudotumour included acetabular component malposition, osteolysis, and acetabular loosening. A retrospective diagnostic accuracy study demonstrated that ultrasound and magnetic resonance imaging (MRI) both had a role prior to HRA revision surgery. However combined ultrasound and MRI was most effective for both identifying and excluding intra-operative pseudotumours. Thus combined imaging may be useful in complex cases. In a prospective longitudinal cohort of 140 asymptomatic HRAs, 11% developed new pseudotumours within five years of initial assessment. No patients with a normal initial ultrasound and low blood metal ions (<2 μg/l) developed new pseudotumours (36% of hips). These patients do not need regular follow-up.
Two large retrospective observational studies were performed involving MoMHA revision procedures recorded in the National Joint Registry for England and Wales. Contrary to previous observations, patients revised for ARMD had half the risk of re-revision and death compared with matched patients undergoing non-ARMD revision surgery (such as for fracture, loosening, and infection). Modifiable predictors of re-revision surgery following ARMD revision were modular component only revisions, and using ceramic-on-ceramic revision bearings.
The clinical impact of pseudotumour following HRA is significant and has continued to increase into the second decade. This thesis has developed an evidence-based approach for the investigation and management of MoMHA patients. No single investigation can universally be used during patient surveillance. However important information has now been provided for risk stratifying patients for surveillance, interpreting blood metal ions, clarifying the roles of imaging, and providing parameters to safely exclude many asymptomatic patients from regular surveillance. The outcomes following ARMD revision surgery have improved since the threshold for performing revision was lowered. However outcomes were influenced by modifiable factors (type of revision procedure and bearing), suggesting that surgeons could reduce failure rates further following ARMD revision procedures.</p
Pseudotumours following hip resurfacing; minimising the clinical impact
Get PDFMetal-on-metal hip resurfacing arthroplasty (MoMHRA) is an alternative treatment option to total hip arthroplasty (THA), especially in the young and active. Despite the early successful results, reports of adverse soft-tissue reactions around the MoMHRA have caused increased concern. These reactions have been termed pseudotumours and have been shown to be associated with increased wear. However, their incidence and aetiology is not known. The broad aims of this thesis were to 1) determine the clinical impact of pseudotumour; and 2) identify ways of reducing the risk of pseudotumour.The clinical impact was determined by examining the incidence and prevalence of pseudotumours needing revision and the subsequent outcome following revision. At the Nuffield Orthopaedic Centre, the 10-year survival of the BHR, commonest MoMHRA used, was 87.1% (95%CI: 83.0% to 91.2%) and the 10-year incidence of revisions due to pseudotumour was 7.5% (95%CI: 4.3% to 10.7%). In a prevalence study of two tertiary referral centres, pseudotumour was identified as the most common revision indication. An outcome based, case-control study characterised outcome following revision due to pseudotumour as inferior to that following revision for any other failure mode, and inferior to the outcome of matched primary THAs. The inferior outcome was associated with the extensive tissue damage at revision.Risk factors contributing to development of pseudotumour were found to be both patient and surgeon related. Patient factors significantly increasing risk included female gender and small component size. Case control studies demonstrated two surgical factors that were associated with significantly increased risk; cup malorientation and a reduction in head neck ratio (HNR) at operation particularly in females. Furthermore, evidence based recommendations were provided on optimum cup orientation and screening practice. Surgeons should aim for a radiographic cup inclination/anteversion zone of 45°/20° ± 10°. Patients with mal-positioned cups, those with high HNR prior to surgery, and those that had significant HNR reduction with the MoMHRA should be considered at increased risk of developing a pseudotumour.An ex vivo study demonstrated that the majority of pseudotumours occur due to high prosthesis wear, and result from an exaggerated innate response with an accompanying variable immune response. However a small but significant number of pseudotumours (20%) were observed with low wear and a prominent immune response. Furthermore, the cups oriented within the optimum zone were associated with less wear.Hence, subsequent in vivo research focused on providing evidence-based guidance on how to achieve the target cup orientation and factors to consider in minimising the scatter in cup orientation observed following hip arthroplasty. This great scatter was mostly due to two factors: 1) the variability between surgeons at orientating a component at implantation and 2) the difference in the pelvic position between implantation and radiographic assessment. The angular offset was 5° for inclination and 8° for anteversion because of the different definitions at impaction and X-Ray. Surgeons should need to be aware of these factors. Greater amount of pelvic movement occurs during MoMHRA, in comparison to THA. To achieve the target MoMHRA cup orientation surgeons should implant the cup with an intra-operative inclination/anteversion of 40°/30°.It is concluded that pseudotumour following MoMHRA has a significant clinical impact. In order to minimise it, surgeons should appropriately select patients and optimise surgical technique to achieve optimum cup orientation and try to avoid reducing the native head neck ratio. Appreciation of risk factors for pseudotumour development (female gender, small size component, cup orientation, HNR reduction), would aid detection prior to extensive soft-tissue damage and improve inferior outcome associated with revision
Assessment of the arthritic knee: Patient selection for Oxford unicompartmental knee arthroplasty
Get PDFThe aim of this thesis was to establish the long-term outcomes of the Oxford medial Unicompartmental Knee Arthroplasty (OUKA), define patient selection criteria and to develop and externally validate an evidence based method of patient selection for this procedure. In the hands of the developer surgeons, outcomes following medial OUKA were found to be good with an implant survival of 94% (95%CI 92 to 96) at ten-years and 91% (95%CI 83 to 98) at fifteen-years. Across the published literature, however, variation in outcomes was observed with a meta-analysis of published series of OUKA finding estimates of ten-year survival ranging from 57% to 100%, mean 88% (95%CI 85 to 90). It was identified that both increased surgical caseload (volume) and increased surgical usage (proportion of primary knee arthroplasty that are OUKA), a surrogate marker of indications, were associated with improved outcomes. Surgical usage, however, was more important, with good results following OUKA seen with high surgical usage, representing broad indications, independent of the surgical volume. This finding, coupled with differences in patient demographics and failure mechanisms between usage groups, highlighted that differences in indications for OUKA may explain the variability in outcomes observed. One reason surgeons may have a low usage is if they apply previously recommended patient factor contraindications based on age (<60 years), weight (&GE;82kg) and activity level (high activity). When disease factors are standardised, however, it was found that patients with these previously reported contraindications often actually did better than those without, and outcomes of knees implanted where all these factors were present were as good as where none were present. Therefore, the decision to proceed with OUKA should be based on the pathoanatomy of disease. Optimal candidates for OUKA should have full-thickness cartilage loss, with bone on bone arthritis, in the medial compartment, as knees with partial thickness cartilage loss were found to have worse functional outcomes and almost three-times the reoperation rate, predominantly for unexplained pain. Provided there was full-thickness preserved cartilage laterally and functionally normal ligaments, the presence of lateral osteophytes and the macroscopic status of the anterior cruciate ligament was not found to influence outcomes, nor did the presence of patellofemoral joint disease (with the exception of lateral facet disease with bone loss and grooving) or anterior knee pain. The pathoanatomy of disease can be identified radiologically, however, standing knee radiograph were found to perform poorly. To identify medial compartment full-thickness cartilage loss either a varus stress radiograph or fixed flexion radiograph, both at 20° flexion and aligned to the joint surface, were identified as the optimum views. To confirm preserved lateral compartment full-thickness cartilage a valgus stress radiograph at 20° flexion, aligned to the joint surface, was identified as the most appropriate technique. As stress radiographs are time and resource consuming, a novel stress device was developed in line with the IDEAL-D framework and validated against the gold standard of manual, clinician performed stress radiographs, as well as independently tested in clinical practice. Finally, to simplify patient selection, an atlas based Decision Aid, combined with a structured radiographic assessment, was developed and externally validated with an accuracy of over 90% at identifying suitability for OUKA. The routine use of this approach would be expected to standardise patient selection and ultimately translate into improved long-term outcomes
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Fixation of the cementless oxford unicompartmental knee replacement
Get PDFThe Oxford Unicompartmental Knee Replacement (OUKR) is an effective treatment for symptomatic end-stage anteromedial osteoarthritis. In contrast with data from specialist centres, the National Joint Registries suggest a higher revision rate than total knee replacement. The cementless version of the OUKR was introduced to prevent cementation errors, improve fixation, reduce the incidence of radiolucent lines and ultimately reduce the discrepancy between the results of specialist centres and National Joint Registries. There are, however, anecdotal reports of tibial plateau fractures with cementless fixation. The aim of this thesis was to assess the clinical outcome and key biomechanical aspects of the fixation of the cementless OUKR.
A systematic review demonstrated that modern cementless unicompartmental knee replacements (UKRs) are safe and effective.
The cementless OUKR had a 10-year survival of 97% and 88% good or excellent clinical results in a prospective, consecutive case series of 1000 cases from two centres.
The primary stability of the cementless OUKR relies on the interference fit. The 5-year results of a randomised controlled trial using radiostereometric analysis demonstrated that cementless components are as stable as cemented. Although sufficient in providing component stability, the interference fit could be excessive increasing the risk of fracture. A biomechanical test was carried out to study the effect of interference on the force required to implant the tibial component (push-in force) and the fixation strength (pull-out force). The results demonstrated that a reduction of the interference up to 50% significantly reduces the force required to implant the components without affecting their primary stability.
In conclusion, the cementless fixation of the OUKR is safe and effective, with excellent long-term survival. The stability of cementless components is reliable and at least as good as that of the cemented implant. However, the interference fit around the tibial component is excessive. A reduced interference fit could decrease the risk of fracture without affecting the stability of the components.</p
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Cost-effectiveness of unicompartmental compared to total knee replacement:a population-based study using data from the National Joint Registry for England and Wales
Get PDFObjectivesTo assess the value for money of unicompartmental kneereplacement (UKR) compared to total knee replacement (TKR).DesignA lifetime Markov model provided the framework for theanalysis. SettingData from the National Joint Registry (NJR) for England andWales primarily informed the analysis. ParticipantsPropensity score matched patients in the NJR who received eithera UKR or TKR.InterventionsUKR is a less invasive alternative to TKR, where only thecompartment affected by osteoarthritis is replaced.Primaryoutcome measuresIncremental Quality-Adjusted Life Years (QALYs) and healthcaresystem costs.ResultsThe provision of UKR is expected to lead to a gain in QALYs compared to TKR for all age andgender subgroups (Male <60: 0.12,60-75: 0.20, 75+: 0.19, Female <60: 0.10, 60-75: 0.28, 75+: 0.44) and a reduction in costs (Male<60: -£1,223, 60-75:-£1,355,75+: -£2,005, Female <60: -£601, 60-75:-£935,75+: -£1,102 per patient over the lifetime). UKR isexpected to lead to a reduction in QALYs compared to TKR when performed bysurgeons with low UKR utilisation, but an increase among those with highutilisation (<10%, median 6%:-0.04, ≥10%, median 27%: 0.26). Regardless of surgeonusage, costs associated with UKR are expected to be lower than those of TKR (<10%: -£127,≥10%: -£758).ConclusionsUKR can be expected to generate better health outcomes andlower lifetime costs than TKR. Surgeon usage of UKR does, however, have asignificant impact on the cost-effectiveness of the procedure. To achieve thebest results, surgeons need to perform a sufficient proportion of kneereplacements as UKR, hence low-usage surgeon may need to broaden theirindications of UKR to achieve this.</p
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