A study to compare the accuracy of acetabular and femoral component position and orientation in total hip arthroplasty (THA) using three different techniques : conventional freehand methods, Corin Optimised Positioning System (OPS)™ and the Intellijoint Hip® infrared navigation system.

Primary total hip arthroplasty (THA), or hip replacement surgery, is predominantly an elective procedure for the treatment of osteoarthritis (OA) in the hip. THA involves insertion of one implant into the head of the femur (long leg bone; femoral component) and one into the pelvis (acetabular component) to achieve a ball and cup design to replace the diseased hip. The angle with which the femoral implant and the acetabular implant are inserted into the bone during surgery dictate how well the ball and socket fit together. The target angles for the implants to achieve the ‘best fit’are typically determined prior to surgery using radiographic images. During surgery, the surgeon will aim to achieve the preplanned target values for implant placement. Optimal orientation of both implants during surgery improves patient’s limb function, satisfaction and the overall survivorship of the implants. Traditionally surgeons have used unassisted, freehand methods to place the implants into a predetermined ‘safe zone’ that is guided by bony landmarks on the pelvis and femur. More recently, assistive technologies have emerged that utilise laser technology or navigational technology to improve positioning of implants to match the preplanned target values. The primary aim of this project is to compare the accuracy of three techniques currently available for positioning of the acetabular and femoral implant components during THA: Group 1: Conventional, unassisted (freehand) methods Group 2: Corin Optimised Positioning System (OPS)™ using patientspecific, imagederived instrumentation and laserassisted positioning technology (IDI+LAT) Group 3: Intellijoint Hip® infrared navigation system only We hypothesise that the technique used for intraoperative positioning of the acetabular cup and femoral components will make no difference to the accuracy in executing preoperatively defined targets. We will test our hypothesis by performing a single site, multisurgeon, prospective randomised controlled trial in patients undergoing unilateral and bilateral THA for advanced osteoarthritis (OA). 1)Recruitment Potential participants who meet the selection criteria will be approached in clinic by the investigating surgeons ( Dr Kaushik Hazratwala and Dr Matthew Wilkinson D are qualified orthopaedic surgeons) and provided information on the study, with an opportunity to ask questions. Willing participants will be asked to provide consent for participation. 2)Consent Each investigator will provide information to the patient of the purpose of the study and what their participation would involve in terms of the type and frequency of assessments throughout the study. The investigators will discuss foreseeable risks involved and potential benefits arising from the completing the study. Each potential participant will be provided an information sheet and invited to discuss taking part in the study with others. Patients will be informed by the investigator that they are free to refuse participation in the study, or to withdraw from the study at any time, without compromising their medical care. Patients will be informed that confidentiality of personal data will be maintained at all times and access to this information will be restricted to authorised personnel only. 3)Pre-Surgery All patients who consent to be enrolled in the study are scheduled for radiographic assessment and standard protocols utilised for the Corin OPS™ 3D planning component will be applied to the current study and performed preoperatively for all study participants.In addition to this, participation in this study requires the completion of four questionnaires (Western Ontario and McMaster Universities Arthritis Index WOMAC, Hip Disability and Osteoarthritis Outcome Score HOOS Jnr, EuroQuol 5 dimensions EQ5D, FJS Forgotten Joint Score). The same four questionnaires will be completed postoperatively. 4)Surgical Procedure THA will be performed according to standard protocols used by the Investigating orthopaedic surgeon. A posterior-lateral approach will be used for all study participants. The recommended surgical techniques for placement of the Trinity™ Advanced Bearing Acetabular System and the MetaFix™ or TriFit TS™ femoral stem will be used, where appropriate. The only difference between study participants will be the technique used to facilitate accurate positioning the femoral and acetabular implants; the intent being to achieve a position that is as close as possible to the preoperatively determined target values. The recommended surgical protocol for the Corin OPS™ IDI+LAP component will be used to assist acetabular and femoral stem placement for study participants in Group 2. The Intellijoint Hip® navigation system will be used according to manufacturer’ surgical protocols to assist acetabular and femoral stem positioning for study participants in Group 3. 5)Study Outcomes The following standard parameters will be assessed on pre- and postoperative radiographs of participants in the current study Date of radiograph/Date of assessment Acetabular inclination Acetabular anteversion Acetabular cup radiographic findings (loosening/migration) Femoral stem version Leg length Horizontal centre of rotation Vertical centre of rotation Preoperatively determined implant sizing and actual implant sizing used Subluxation Loosening Cysts Fractures