Distal radius fracture: epidemiology, outcome, and the prediction of instability

INTRODUCTION: Distal radius fracture as an injury appeared in the literature 2400 years ago. It was only recognised as a fracture 220 years ago. That it was not a benign fracture was only recognised 60 years ago. Attempts to improve the surgical treatment of the fracture have only been in the last two or three decades. The introduction of this thesis outlines the history of distal radius fracture, describes the relevant anatomy, and describes the methods used to classify and measure the fracture. The aims of the thesis are presented with respect to the main deficiencies in our strategies for the management of the fracture, namely an inability to predict how the fracture will behave.MATERIALS AND METHODS: The studies in the thesis are divided into two broad sections. The first section is descriptive. Data were collected prospectively over a five-and-one-half year period for approximately 4000 fractures. Validation of the data is performed. The data are used to describe the epidemiology of the fracture in the Lothian Region, and the anatomical outcome of the fracture. Multiple logistic regression analysis of the data is performed to identify those factors (recordable at patient presentation) that are prognostic of outcome. The statistical method used provides weighted significance for each of these factors, and thus mathematical formulae predictive of outcome are constructable. A number of formulae are produced, depending on the displacement of the fracture at presentation (minimally displaced or displaced), and on the outcome measure (early and late instability, the risk of malunion, and carpal malalignment). The second section is validative. The studies in this section are an assessment of the performance of the mathematical formulae in the clinical setting. In the first study, data are collected prospectively for 139 patients, and outcomes recorded. Blinded to outcome, the formulae are applied to each patient's data to calculate the percentage risk of poor outcome. The sensitivity and specificity of mathematical prediction of outcome are calculated. In the second study, a group of clinicians involved in fracture management are asked to predict fracture outcome using first clinical experience and then the predictive formula. This is done using forty radiographs of displaced fractures of known outcome. The two methods of prediction are then compared.RESULTS: The distal radius fracture occurred predominately in the older female patient following a simple fall. The fracture in this typical patient was usually unstable. The most consistently important predictors of fracture outcome were patient age, fracture displacement, comminution and ulnar variance. The mathematical formulae were able to correctly predict anatomical outcome in approximately 7/10 patients in the validative study. This was a significant improvement upon the predictive accuracy of the clinicians using experience alone. Use of the predictive formula also significantly reduced inter-observer variation in the assessment of fracture stability.CONCLUSION: Use of the predictive formula in the Accident & Emergency setting could improve decision-making in fracture management. By promoting an assessment of fracture stability rather than fracture displacement, appropriate management choices are facilitated. The unstable fracture can be referred for operative management, and ineffective closed reduction avoided. The thesis also demonstrates the potential value of the method employed. Multiple logistic regression analysis may provide a guide to treatment where the management of the condition is dependent upon the natural history

Prevalence of asthma, atopy and bronchial hyperresponsiveness and their interrelation in a semi-rural area of Chile

OBJECTIVE: To assess the prevalence of asthma symptoms and their association with sensitisation to eight allergens and bronchial hyperresponsiveness (BHR) to methacholine. SETTING: A random sample of 1232 adults, aged 22 to 28 years, studied in a Chilean semi-rural area. DESIGN : A cross-sectional design for the purpose of this analysis. RESULTS: The prevalence of wheeze was 27.4% (95%CI 24.9-29.9) and waking with breathlessness 13.7% (95%CI 11.8-15.6), higher than the results of a multi-centre European study. Only 7.8% (95%CI 6.3-9.3) had a positive BHR (≤8 mg/ml) and 26.3% (95%CI 23.8-28.8) were atopic. The Youden index of asthma symptoms in non-atopic subjects varied from 0.184 to 0.259 when using BHR as gold standard for asthma, and increased from 0.379 to 0.504 among those with positive atopy. Only 4.5% reported asthma, and the Youden index was slightly higher in comparison to the asthma symptom groups. CONCLUSION: The prevalence of asthma symptoms in young adults was high, but o

Measurement of Ulnar Variance on Uncalibrated Digital Radiographic Images

Uncalibrated digital radiographs used in multicenter trials hinder quantitative measures such as articular step and ulnar variance. This investigation tested the reliability of alternative measures of ulnar variance that are scaled to the length of the capitate. A sample of 30 sets of radiographs from patients enrolled in a prospective study of operative treatment of fractures of the distal radius were blinded and randomized. Five observers measured the ulnar variance (UV) and longitudinal length of the capitate (CH) on two separate occasions with greater than 2 weeks between measurements. During each measurement session, the observers made the measurements on both a calibrated and a noncalibrated workstation. The ratio of the ulnar variance to the length of capitate was calculated (UV/CH ratio). Paired t tests were used to compare two rounds of measurements for both methods. Intra- and interobserver reliability was assessed by the Pearson product-moment correlation coefficients. The ratios were compared using analysis of variance with a Bonferroni correction. The intraobserver reliability was excellent for each of the three variables (UV, CH, UV/CH ratio) for each workstation. The interobserver reliability of the UV/CH ratios obtained for each workstation was moderate to excellent as judged by the Pearson correlations between observers. The Bland–Altman method indicated a mean difference in UV/CH between calibrated and uncalibrated measurement techniques of 0.002 with limits of agreement of −0.11 to 0.11. Measurements of ulnar variance that are scaled to the length of the capitate may be useful measures of deformity in studies that utilize uncalibrated digital radiographs