Functional outcomes in patients undergoing Primary and Revision Hip Arthroplasty

Patients undergoing total hip replacement for osteoarthritis at the Royal Adelaide Hospital, Calvary Adelaide Hospital, St Andrew's Hospital, Adelaide and Western Hospital, Adelaide will be screened for eligibility. Patients who are eligible and consent to participate will be invited to take part. In order to determine the primary outcomes of this study, participants will undergo the following assessments: 1. Two CT scans: Each patient undergoes a pre-operative and post-operative CT scan to assess changes in the hip geometry during surgery. The post-operative CT scan is a standard clinical investigation in THR cases in our institution. The pre-operative CT scan is standard clinical investigation for revision THR; but is an additional scan for primary THR patients in the trial (Ethics approved). The preoperative CT scans will be carried at Dr Jones and Partners or the Royal Adelaide Hospital; and the post-operative scans will be carried out at the respective hospital. The estimated time required to complete one CT scan is 10-15 minutes. Both CT scans do not require contrast. The scans are performed by a radiographer and reported on by a radiologist as per standard clinical practice. 2. Radiostereometric analysis: Radiostereometric analysis (RSA) is a low-dose radiographic method that uses peri-prosthetic tantalum beads as a spatial frame of reference to monitor the stability of arthroplasty implants. It is 5-8 times more sensitive to measure implant migration as compared to plain X-Rays and has been used clinically since 1972. The tantalum beads (1mm and 0.8mm) are inserted intra-operatively during surgery using a bead inserter. Nine beads (1mm) are inserted in the acetabular bone and nine beads (1mm) are inserted in the proximal femur. Three beads each (0.8mm) are inserted in the distal and proximal cement mantle. All patients will undergo a post-operative RSA examinations on day 2, 6 weeks, 3 months, 12 months and 24 months. Routine radiographs (AP pelvis, AP hip, lateral and rolled lateral views) used in standard clinical review of THR at the RAH will be taken at the same time points. In some complex cases, an additional time point of 6 months may be added, if required clinically. It takes approximately 10-15 minutes to complete RSA examination and the scans are taken by trained radiographer in collaboration with a RSA trained Research Assistant. 3. Gait assessments: In addition, patients will undergo a gait assessment at the dedictaed Gait Laboratory in the University of Adelaide Health and Medical Science Building (AHMS) pre-operatively, 6 weeks, 3 months, 6 months, 12 months and 24 months. In some complex cases, an additional time point of 6 months may be added, if required clinically. Each gait exam utilises a 10-camera Vicon Motion Capture. The software Vicon Nexus controls the cameras, calibration, capture, identification and export of data. Data from force plates (force and motion capture) and dynamic electromyography (EMG) is also integrated in the system. Fourteen EMGs will be placed on the lower limb covering the following muscle groups- Tibialis anterior, Peroneus longus, P.Brevis, Soleus, quads, gastrocnemius, Gluteus max and min, biceps femoris, semitendinosus and adductor longus to investigate the patterns of muscle activity during gait. The estimated time required to complete a gait assessment is 45 minutes. Gait assessments are conducted by Researcher Assistant staff member, graduate of Applied Science (Biomechanics and Human Movement). 4. Hip and Osteoarthritis Outcome Score (HOOS): All patients are requested to answer HOOS questionnaire which is a validated questionnaire in patients with hip osteoarthritis to measure domains of pain, stiffness, quality of life, daily living and sports/recreation. It takes 10 minutes to complete this questionnaire. 5. Activity and Sleep patterns: Patients are asked to wear a GeneActiv physical activity monitor for one week continuously following their gait assessment appointments. This will be used to monitor the patients’ activity during their daily living before surgery (baseline assessment) and following surgery to provide some objective data on the frequency of loading during recovery. The GeneActiv device is a wristwatch-type accelerometer, which can be worn 24 hours a day during all activities (excluding showering, bathing and swimming). Verbal instructions will be provided to patients, and they will be advised that it requires no user input. Accelerometers will be set to capture data at 50 Hz and uploaded data using GENEActiv PC Software version 3.1. The data will be processed in custom MATLAB software. A pre-paid envelope is provided to participants so they can post back the watch to the investigators after one week.