Title: An Automated System for Measuring Hip Dysplasia in Children with Cerebral Palsy
Funder: Department of Health and Social Care

Abstract: Background : Cerebral Palsy (CP) is the most common motor disability in childhood, and managing the needs of these children accounts for 50% of elective care provided by children’s orthopaedic surgeons. In particular, affected children are at high risk of hip dislocation, with more than 90% of children with more severe disease having displaced hips. As part of the new Cerebral Palsy Integrated Pathway (CPIP) children with CP undergo regular physical and radiological examinations. Radiographs, taken as often as every 12 months, are used to measure the proportion of the femoral head outside the acetabulum (Reimer’s Migration Percentage, RMP) in order to inform decisions about intervention. The measurement is currently made manually, which is time-consuming and prone to inconsistencies. Aims and Objectives : We will develop a system for automatic analysis of radiographs of children’s hips. We will focus on measurements required for monitoring CP (hip dislocation), but in the longer term will expand the system to cover the four most common childhood hip diseases. Approach : We have a large collection of radiographs of the hips of children and have developed software that can automatically locate the outline of the proximal femur to within about 1mm. During this project we will select and annotate images with different degrees of hip dysplasia, to extend our models to (a) include the outline of the acetabulum (required for measuring dysplasia) and (b) deal with a wider range of examples. We will evaluate the accuracy of the system, comparing it to manual measurements made by clinicians. Deliverables : A working prototype for automatically measuring RMP ready for wider clinical evaluation. Anticipated Impact : When rolled out nationally, the system will help identify children at risk of hip dislocation, save clinician time and will ensure prompt, consistent diagnoses to facilitate equal access to cerebral palsy services across the UK.

Lay abstract: Background: Cerebral palsy (CP) is the most common disability of childhood. Affected children are at high risk of developing hip dislocation &ndash; where the ball of the joint moves out of the socket in the pelvis. This leads to severe pain and difficulties with personal care. Hip dislocation can be prevented by early intervention if signs can be spotted early on hip x-rays. Currently, these x-rays are examined by clinical experts to identify when the ball begins to move out of the socket. However, this process is time consuming, prone to error and it does not readily enable doctors to identify important trends. Aims: The goal of this project is to develop software which will measure hip dislocation automatically, saving time and ensuring that similar standards are applied across different hospitals. Methods: As part of our work on studying childhood hip diseases, we have developed software which can automatically locate the outline of the bones in the hip in X-ray images. This is accurate to within about 1mm. The system learns from examples &ndash; previously we have shown it many examples of normal hips and those showing signs of Perthes (a rare childhood hip disease). In this project we will train the system to find the outlines of hips with varying amounts of dislocation, and to compute the amount of dislocation from the bone outlines. We are currently collecting anonymised images from children with CP, taken as part of routine hip surveillance. We will manually place points on the images to define the outline of the important bones. These will be used to train the system, and to test how well the system can do on new images. We will compare the automatic measurements to those of experts. Patient Involvement: We have a close affiliation with STEPS UK and Action CP, who have committed to offer input throughout the study. Meetings will be held with patients and family members, led by experts in patient involvement. Dissemination: We will describe the results of our work at academic conferences and in journals, alongside which we will publish lay summaries of our work. We will use the networks of STEPS and Action CP to maximise the knowledge base within the CP community. Clinical Impact: This will be the first step towards building a system for use in the clinic. If successful, we will proceed to produce a prototype which can be tested and certified to use in hospitals. Although initially focused on measurements for monitoring children with CP, in the long term we will generalise the software to identify a range of childhood hip diseases; particularly rare ones that are frequently missed with life-long consequences (e.g. Slipped Femoral Epiphysis).

Research activity codes: 7.3 MANAGEMENT AND DECISION MAKING
Health categories: NEUROLOGICAL;MUSCULOSKELETAL