The arc of pelvic motion has been shown to be as great as 70 through sit to stand activities 1 DiGioia CORR 2006

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2 The arc of pelvic motion has been shown to be as great as 70 through sit to stand activities 1 DiGioia CORR 2006

3 Overview Every patient moves differently 1 and their total hip replacement should be optimised to account for this. The orientation of the acetabular cup is one of the most important factors under the surgeon s control 2, and acetabular cup orientation has a significant effect on device performance, including patient outcomes, impingement, edge loading, bearing wear, osteolysis and loosening 3,4. There remains two key issues with THR today: 1 2 What is the target for a well orientated cup? Are we able to achieve that orientation? 1 Implant orientation Clinical issue Safe zones There have been various attempts to define a safe zone for the orientation of an acetabular cup, and increasing evidence to suggest that one generic zone is not applicable 5,6,7,8,9. Clinical solution Pelvic tilt Pelvic tilt is an important consideration for a patient s physiological profile, and the arc of pelvic motion in some patients can be as mobile as 70 and in others as stiff as 5 during functional activities 1,10. This can have significant impact on the functional orientation of the acetabular cup. What is the optimal cup orientation for an individual patient? OPS is a state-of-the-art technology platform that identifies a target orientation unique to each individual. These target orientations are calculated from a dynamic pre-operative functional simulation, which accounts for the patient s physiological profile throughout a range of daily activities.

4 2 Delivery Clinical issue Intra-operative tools It is inherently difficult to position the cup during surgery and achieving a target orientation is a considerable challenge in THR. It has been shown that up to 50% of surgeries miss the intended orientation 11 and the chance of hitting a target to within 5 can be as low as 21.5% 12. Clinical solution How is the optimised position delivered during surgery? Once the target orientation for a specific patient has been decided, a unique guide is produced for the individual. The planned orientation is built into the axis of the guide which is used intraoperatively with a simple laser system to allow the surgeon to deliver on the planned cup orientation.

5 3 Femoral Clinical issue The final position and orientation of the femoral component in total hip arthroplasty can be directly affected by the femoral neck osteotomy. Recent literature suggests that both the level and angle of the femoral neck resection can impact the varus / valgus position as well as the anteversion of the definitive component 13. This is an important consideration in reconstructing hip biomechanics, which if done poorly, has been associated with higher rates of dislocation, muscle weakness, limping, leg length discrepancy, impingement and early loosening of the implant 14. Controlling the osteotomy should be considered in optimising the position of the femoral component. Clinical solution The femoral neck resection can be accurately controlled by utilising the OPS femoral osteotomy guide. Once the target osteotomy plane has been identified using pre-operative three-dimensional templating software, a unique, patient specific 3D printed guide is created. The OPS femoral osteotomy guide incorporates an open capture system that controls the resection, allowing the surgeon to precisely recreate the pre-operative femoral plan.

6 Reference: 1. DiGioia AM, Hafez MA, Jaramaz B, Levison TJ, Moody JE, Functional pelvic orientation measured from lateral standing and sitting radiographs. Clin Orthop Relat Res 453: Echeverri S, Leyvraz P, Zambelli P, et al. Reliable acetabular cup orientation with a new gravity-assisted guidance system. J Arthroplasty 2006; 21(3): Meftah M, Yadav A, Wong AC, Ranawat AS, Ranawat CS. A novel method for accurate and reproducible functional cup positioning in total hip arthroplasty. J. Arthroplasty 2013; Aug:28(7): Harrison C, Thomson AI, Cutts S, Rowe PJ, Riches PE, Research synthesis of recommended acetabular cup orientations for total hip arthroplasty. J. Arthroplasty Yoon Y, Hodgson AJ, Tonetti J, et al. Resolving inconsistencies in defining the target orientation for the acetabular cup angles in total hip arthroplasty. Clin Biomech 2008; 23: McCollum DE, Gray WJ. Dislocation after total hip arthroplasty. Causes and prevention. Clin Orthop Relat Res 1990; 261: Harris W. Advances in surgical technique for total hip replacement: without and with osteotomy of the greater trochanter. Clin Orthop Relat Res 1990; 146: Pedersen DR, Callaghan JJ, Brown TD. Activity-dependence of the safe zone for impingement versus dislocation avoidance. Med Eng Phys 2005; 27: Lewinnek GE, Lewis JL, Tarr R, Compere CL, Zimmerman JR. Dislocations after total hip-replacement arthroplasties. J Bone Joint Surg [AM] 1978; Mar:60-A;2 10. SA, Yeung E, Jackson MP, Rajaratnam S, Martell JM, Walter WL, Zicat BA, Walter WK. The role of patient factors and implant position in squeaking of ceramic-on-ceramic total hip replacements. J Bone Joint Surg 2011; Apr: 93-B,4 11. Callanan MC, Jarrett B, Bragdon CR, Zurakowski D, Rubash HE, Freiberg AA, Malchau H. Risk factors for cup malpositioning quality improvement through a joint registry at a tertiary hospital. Clin Orthop Relat Res 2011; 469: Bosker BH, Verheyen CCPM, Horstmann WG, Tulp NJA. Poor accuracy of freehand cup positioning during total hip arthroplasty. Arch Orthop Trauma Surg 2007; 127: Dimitriou D, Tsai T, Kwon Y. The effect of femoral neck osteotomy on femoral component position of a primary cementless total hip arthroplasty. International Orthopaedics Girard J, Lavigne M, Vendittoli P.-A, Roy A. G. A randomised study comparing total hip resurfacing and total hip arthroplasty. J Bone Joint Surg [BR] Get the full picture. Scan to view the OPS introductory video. OPT-REC-MK-09 Rev 1