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

Abstract

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.