Epidemiological Studies in Orthopaedics: A Brief Overview

Despite rising numbers of randomised controlled trials (RCTs) being undertaken, for many research questions in trauma and orthopaedics, randomisation is often either unfeasible or inappropriate. There has been a historical natural reliance on observational studies expanding the evidence base, and these are commonly referenced both in published work and during the process of day-to-day clinical decision making. Prior to the advent of large-scale databases, institutional case series of diagnoses and interventions accounted for the vast majority of observational studies within our specialty. The advantage of these case series is the potential breadth of data collected on a clearly defined population – these can be used to pose study questions for higher quality research or in many cases may answer questions definitively in their own right. However, there is wide variation in the quality of reporting, they are often single-surgeon retrospective studies, and generalising findings can be problematic. Epidemiological studies using registries are surely then the solution, or are they? Arthroplasty registries, designed initially to identify poorly performing implants, have led the way in terms of collecting national-level longitudinal data on individuals undergoing an orthopaedic intervention. The Swedish Arthroplasty Register is the oldest joint registry in the world and, since its creation, the number of worldwide registries has increased. The National Joint Registry of England and Wales (NJR) is the largest arthroplasty registry with over a million recorded procedures. In the UK, there are now several other orthopaedic registries including the Non-Arthroplasty Hip Register, the UK …