Over 10% of total hip arthroplasty (THA) surgeries performed in England and Wales are revision procedures1. Malorientation of the acetabular component in THA may contribute to premature failure. Yet with increasingly younger populations receiving THA surgery (through higher incidences of obesity) and longer life expectancy in general, the lifetime of an implant needs to increase to avoid a rapid increase in revision surgery in the future. The Evaluation of X-ray, Acetabular Guides and Computerised Tomography in THA (EXACT) trial is assessing the pelvic tilt of a patient by capturing x-rays from the patient in sitting, standing and step-up positions. It uses this information, along with a CT scan image, to deliver a personalised dynamic simulation that outputs an optimised position for the hip replacement. A clinical trial is currently in place to investigate how the new procedure improves patient outcomes2. Our aim in this project was to assess whether accurate functional assessment of pelvic tilt could be further obtained using inertial measurement units (IMUs). This would provide a rapid, non-invasive triaging method such that only patients with high levels of tilt measured by the sensors would then receive the full assessment with x-rays. Recruited patients were fitted with a bespoke device consisting of a 3D-printed clamp which housed the IMU and fitted around the sacrum area. A wide elastic belt was fitted around the patient's waist to keep the device in place. Pelvic tilt is measured in a standing, flexed seated and step-up position while undergoing X-rays with the IMU capturing the data in parallel. Patients further completed another five repetitions of the movements with the IMU but without the x-ray to test repeatability of the measurements. Statistical analysis included measures of correlation between the X-ray and IMU measurements.Background
Methods
