Ideally the hip arthroplasty should not be subject to bony or prosthetic impingement, in order to minimise complications and optimise outcomes. Modern 3d planning permits pre-operative simulation of the movements of the planned hip arthroplasty to check for such impingement. For this to be meaningful, however, it is necessary to know the range of movement (ROM) that should be simulated. Arbitrary “normal” values for hip ROM are of limited value in such simulations: it is well known that hip ROM is individualised for each patient. We have therefore developed a method to determine this individualised ROM using CT scans. CT scans were performed on 14 cadaveric hips, and the images were segmented to create 3d virtual models. Using Matlab software, each virtual hip was moved in all potential directions to the point of bony impingement, thus defining an individualised impingement-free 3d ROM envelope. This was then compared with the actual ROM as directly measured from each cadaver using a high-resolution motion capture system. For each hip, the ROM envelope free of bony impingement could be described from the CT and represented as a 3d shape. As expected, the directly measured ROM from the cadaver study for each hip was smaller than the CT-based prediction, owing to the presence of constraining soft tissues. However, for movements associated with hip dislocation (such as flexion with internal rotation), the cadaver measurements matched the CT prediction, to within 10°. It is possible to determine an individual's range of clinically important hip movements from a CT scan. This method could therefore be used to create truly personalised movement simulation as part of pre-operative 3d surgical planning.
After failed acetabular fractures, total hip arthroplasty (THA) is a challenging procedure and considered the gold standard treatment. The complexity of the procedure depends on the fracture pattern and the initial fracture management. This study’s primary aim was to evaluate patient-reported outcome measures (PROMs) for patients who underwent delayed uncemented acetabular THA after acetabular fractures. The secondary aims were to assess the radiological outcome and the incidence of the associated complications in those patients. A total of 40 patients underwent cementless acetabular THA following failed treatment of acetabular fractures. The postoperative clinical and radiological outcomes were evaluated for all the cohort.Aims
Methods
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 due to mechanisms such as edge loading and prosthetic impingement. It is known that the pelvis flexes and extends during activities of daily living (ADLs), and excessive pelvic motion can contribute to functional acetabular malorientation. Preoperative radiographs can be performed to measure changes in pelvic tilt during ADLs to identify high risk individuals and inform surgical decision making. However, radiographs require time-consuming radiation exposure, and are unable to provide truly dynamic 3-dimensional analysis. The purpose of this study was to develop and evaluate a motion capture method using inertial measurement units (IMUs). This would provide a rapid, non-invasive analysis of pelvic tilt which could be used to support surgical planning. Patients awaiting THA were fitted with a bespoke device consisting of a 3D-printed clamp which housed the IMU and positioned over the sacrum. A wide elastic belt was fitted around the patient's waist to keep the device in place. Movement data was transmitted wirelessly to a tablet computer. Pelvic tilt was measured in standing, flexed seated and step-up positions while undergoing X-rays with the IMU capturing the data in parallel. Statistical analysis included measures of correlation between the X-ray and IMU measurements.Background
Methods
It is not always clear why some patients experience recurrent dislocation following total hip arthroplasty (THA). In order to plan appropriate revision surgery for such patients, however, it is important to understand the specific biomechanical basis for the dislocation. We have developed a novel method to analyse the biomechanical profile of the THA, specifically to identify edge loading and prosthetic impingement, taking into account spinopelvic mobility. In this study we compare the results of this analysis in THA patients with and without recurrent dislocation. Post-operative CT scans and lateral standing and seated radiographs of 40 THA patients were performed, 20 of whom had experienced postoperative dislocation. The changes in pelvic and femoral positions on the lateral radiographs were measured between the standing and seated positions, and a 3D digital model was then generated to simulate the movement of the hip when rising from a chair for each patient. The path of the joint reaction force (JRF) across the acetabular bearing surface and the motion of the femoral neck relative to the acetabular margin were then calculated for this “sit-to-stand” movement, in order to identify where there was risk of edge loading or prosthetic impingement.Background
Methods
Patient related outcome measures (PROMS) are now routinely undertaken in patients undergoing hip arthroplasty. These are in the form of the Oxford Hip Score (OHS) and EQ5D questionnaires pre-operation and at 6 months' post operation. MYMOPS is a patient specific outcome measure that allows patients to list their individualised symptoms and activities that are limited and is used is other medical specialities but not currently within orthopaedic surgery. The aim of this study was to validate the MYMOPS questionnaire for use in hip arthroplasty by comparing it to the OHS. At a single centre, 50 patients were recruited to our prospective trial after ethical approval. A MYMOPS questionnaire and an OHS was filled in pre-operation and then at 6 months post-operatively. 6 patients filled in either form incorrectly and were excluded. The remaining 44 included 30 females and 14 males with an average age of 68.5 (range 35–90).Introduction
Patients/Materials & Methods
This clinical study aims to establish the rate of operative inadvertent hypothermia (IH) in elderly hip fracture patients (>65 years old). We postulate that differences exist in risk factors and hypothesised poorer outcomes in patients with IH. A single centre, retrospective study of 929 hip fracture patients managed operatively between June 2015 and July 2017 was conducted. Patients’ demographic, anaesthetic and surgical variables were analysed together with outcomes for length of stay (LOS), 30-day re-admissions, and 30-day mortality.Background
Methods
