Grant: Catalyst Gr: Address. Musculoskeletal Cond./Arthritis in Cnds- Joint replacement

Over 58,000 total hip replacements (THR) are performed in Canada per year to treat end-stage osteoarthritis. Unfortunately, approximately 8.2% of patients sustain a complication and must undergo a reoperation (revision surgery). Revisions are associated with physical and psychological burden to patients and cost the healthcare system a lot of money. The second most common reason for revision is instability (i.e. dislocation) of the implant components. Orientation of the implanted cup (acetabular component) has been shown to improve the articulation's performance and is a key factor to joint's stability. Unfortunately, no research to date has been able to establish a 'safe' cup orientation to eliminate the risk of instability after a THR. This may be because most research has focused on one-dimensional evaluation and has not considered the individual's anatomy and motion patterns. Our group has recently published on two and three-dimensional assessment of the hip and the spine to study individual spino-pelvic dynamics and how that influences outcomes after surgery. Furthermore, we have studied the arthritic patients' spine-, pelvis-, hip- and femur- dynamics before and after surgery and have established protocols of how to best investigate these with radiographs. As such, it is now known that the orientation of the cup is influenced by the individual's anatomy and movement pattern and that the movement pattern does not significantly differ before and after a THR. Through this prospective research project, we aim to (1) determine the optimum cup orientation in patients undergoing a THR and (2) assess what the relative size this optimum zone of cup orientation is, as this would have implications for the patient and the surgeon. Our hypothesis is that for most patients, the relative size for optimum/safe cup orientation is large enough for surgeons to be able to achieve that target without the need for new and expensive technologies.