Establishing image quality criteria for lateral knee radiographs

Abstract

Introduction Lateral knee radiographs are frequently performed x-ray projections with a high retake rate. A reason for lateral knee radiograph retakes is inconsistent imaging protocols. A variation in the literature exists regarding the image quality criteria required for lateral knee radiographs. Purpose of the study The purpose of the study was to establish an image quality criteria list for lateral knee radiographs. A standardised list would make it easier for radiographers to decide whether an image should be retaken or not. Methodology This study was conducted at a public general hospital in Malta. A prospective research design was used to collect quantitative data. This study was divided into three parts. The first part of the study consisted of the collection of 25 lateral knee radiographs. In the second part, image quality criteria for lateral knee radiographs were drawn up and validated by experts in the field. The third part of the study consisted of the distribution of the research tool to radiographers and orthopaedic surgeons. The participants were asked whether they would keep or retake 25 lateral knee radiographs according to the established criteria. The extent to which every criterion was met was rated using a 4-point Likert scale. The Mann-Whitney test was used to compare mean rating scores provided to every criterion related to image quality in this study. Results A total of 21 participants filled in the research tool. The participants consisted of 16 radiographers and 5 orthopaedic surgeons. Based on the clinical study results, the six main image quality criteria for lateral knee radiographs, in order of importance, obtained from this study were the following: 1. The knee joint is seen in the lateral position as evidenced by the superimposition of the femoral condyles. 2. The patella can be seen in lateral profile with joint space between the patella and femur well demonstrated. 3. The patella is projected clear of the femur. 4. The proximal tibia slightly superimposes the head of the fibula. 5. The knee joint is in the centre of the collimated field. 6. Fat pad and sharp trabecular markings. Conclusions This study identified an image quality criteria list that may assist radiographers when determining if retakes of lateral knee radiographs are necessary or not. However, further research is required by using a larger sample size and conducting the study in different medical imaging departments.