Patent ID: 9662228
Date: 2017-05-30
CPC Classifications: A61B,A61F

Claim:
1. A method for aligning an acetabular cup insertion instrument using an operating room digital x-ray system and an operating room navigation or orientation tracking system, the method comprising: taking a single lateral pre-operative x-ray digital image and an anterior-posterior pre-operative x-ray digital image of a standing patient's pelvis; determining on the pre-operative digital x-ray images a natural pelvic tilt angle by defining an anterior pelvic plane (APP) and determining an angle between the APP and a coronal plane perpendicular to a surface on which the patient is standing; wherein the APP is defined on the anterior-posterior pre-operative digital x-ray image by first, second and third points on the pelvis; the first, second and third points are a pubic symphysis, a left anterior superior iliac spine and a right anterior superior iliac spine; calculating lengths and angles between each of the APP points in the anterior-posterior pre-operative digital x-ray, and calculating the angle between the APP and the coronal plane, and a distance between the point of the pubic symphysis and a promontory point in the lateral pre-operative digital x-ray image; placing the patient on a surface of an operating room table in a supine position; wherein the operating room table has a tracking element or navigation tracking system; placing a position tracking device on the patient's pelvis to intra-operatively track movement of the pelvis during surgery; wherein the position tracking device is used to intra-operatively locate the first, second and third points defining the pubic symphysis, and the left and right anterior superior iliac spines when the patient is in a supine position on the operating room table; thereafter using the operating room navigation or the orientation tracking system to intra-operatively relocate the points defining the APP in an anterior-posterior intra-operatively digital x-ray image and a distance between the point of the pubic symphysis and a promontory point in an lateral intra-operative digital x-ray image; thereafter locating the coronal plane by using the determined natural pelvic tilt angle and APP plane in the lateral intra-operative digital x-ray image; calculating lengths and angles between each of the APP points in the anterior-posterior intra-operative digital x-ray, and calculating the angle between the APP and the coronal plane, and a distance between the point of the pubic symphysis and a promontory point in the lateral intra-operative digital x-ray image; comparing dimensional differences between the points and angles on the pre-operative standing x-ray images and the intra-operative supine x-ray images to calculate the intra-operative pelvic angular deviation and position changes in orientation relative to the pre-operative pelvic position and to calculate a desired correcting anteversion angle with respect to the coronal plane; and using the operating room navigation or the orientation tracking system to orient the acetabular cup insertion instrument having a position tracking device mounted thereon at the desired correcting predetermined anteversion angle with respect to the coronal plane.