The purpose of this app is to provide the orthopaedic hip reconstruction surgeon with a tool to help identify which patients may be at higher risk for dislocation and guide acetabular cup placement in total hip arthroplasty (THA). Every patient has unique spinopelvic mechanics and as the pelvis moves, so does the cup. The orientation of components placed with the patient positioned on the operating table will change post-operatively when the pelvis is in functional positions that may increase the risk of dislocation if cup position is not accounted for.
This may be due to a patient's inability to adequately adjust his or her pelvis and cup in high-risk positions such as sitting. This may be due to anatomy or lumbopelvic stiffness. This app is based on a geometric relationship between a patients planned cup position and pelvic motion from standing to sitting, and the resultant functional anteversion when sitting. It is intended to be used clinically during pre-operative planning to help define a patient-specific anteversion safe zone that can be applied to intra-operative cup placement.
The numbers generated in this app are intended to serve as a general guide for intra-operative anteversion cup placement. Other patient factors such as bony anatomy, abductor competency, femoral component placement, and soft tissue repair must also be considered by the surgeon to determine the most appropriate cup position for a given patient.
Thank you for using our app, we hope you find it helpful!