Today's News

Thursday, March 1, 2001

New positioning guide for use in THR aligns acetabular

A simple, new acetabular component positioning guide for use in total hip replacement (THR) uses internal pelvic landmarks to align the acetabular component.

This new guide, displayed in scientific exhibit 59 by Tim P. Lovell, MD, Spokane, Wash., is based on referencing the polar axis of the acetabular component. There are two arms to the guide; one points at and touches the anterior superior iliac spine (ASIS) and the other hooks in the greater sciatic notch (GSN).

To use the guide, the trial or final component is placed in the acetabulum, attached to the guide. The ASIS arm tip is placed on the patient's ASIS. The GSN arm determines the amount of anteversion the component will see. The GSN arm length adjusts the amount of anteversion by moving the polar axis away from the GSN. The greater sciatic notch arm tip is then kept hooked in the GSN and the arm rod is slid in that arm upright to the calculated distance.

The acetabular component or trial is now located correctly, independent of patient position, pelvic tilt, etc. Anteversion and abduction of the final component was measured using the technique of Seradge on the AP pelvis x-ray.

Initial use of the guide in 26 THR has resulted in acetabular component positioning with abduction of 40 degress (+/- 4 degrees) and anteversion of 21 degrees (+/- 5 degrees).

Funding was provided by Stryker Howmedica Osteonics.

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Last modified 20/February/2001 by IS