Total Hip Arthroplasty
THA ACA – The axis for surgical success
More accurate acetabular cup positioning techniques will be important for contemporary total hip arthroplasty (THA). The THA ACA (ACA: Acetabular Center Axis) software is patient-specific, independent of variations in anatomy or pelvic position. It gives the surgeon the orientation of reamer in relation to the acetabular center axis of rotation and therefore determines precisely the cup position. The cup center should preferably coincide within 4 mm of acetabular center axis to maximize stability and to minimize impingement that may result in accelerated wear, reduced range of motion, dislocation or unexplained pain. The system relies on readily accessible anatomic landmarks of the acetabulum, making it significantly attractive for surgeons who use CT-free planning. Leg length and offset information are achieved by palpating specific points on the leg. THA ACA is also especially suitable for less invasive surgical technique.
Software Elements
Palpation of Landmarks
The camera tracks the position of the transmitter fixed rigidly to the pelvis. By palpation of exact defined landmarks, the individual anatomy of the patient is recorded as basis for all further navigation steps.
Navigation of the Acetabulum
With help of navigated instruments, the hip socket is prepared and the Plasmacup is implanted. This way the position and alignment of the implant adapted to the individual anatomy of each patient can be achieved. The reaming depth is displayed in relation to the hip socket floor and therefore allows a safe reaming and an avoidance of a protrusion.
Navigation of the Hip Stem
The preparation of the femur is also performed by means of navigated instruments. Aim is the control and correction of leg length discrepancies and offset changes in a mm-range.
At the end of the surgery, the result is recorded and all data is available for documentation purposes.