Image Guided Navigation System to Measure Intraoperatively Acetabular Implant Alignment

TLDR

Little clinical research has examined how patient positioning and pelvic motion affect acetabular implant alignment during total hip replacement. The study aims to develop and evaluate a clinical navigation system that measures pelvic position and acetabular alignment intraoperatively to improve surgical precision. HipNav continuously and precisely tracks pelvic location and relative implant alignment, providing image‑guided measurement tools and assist devices to surgeons. Implementation of HipNav revealed large, unpredictable pelvic variations, that mechanical guides fail to account for, leading to variable and often unacceptable acetabular alignment, and that press‑fitting oversized components alters cup orientation.

Abstract

There has been little clinical research to examine the effects of patient positioning and pelvic motion on the alignment of the acetabular implant during total hip replacement surgery. Until now, no tools were capable of accurately measuring these variables during the actual procedure. As part of a broader program in medical robotics and computer assisted surgery, a clinical system has been developed that includes several enabling technologies. The hip navigation system (HipNav) continuously and precisely measures pelvic location and tracks relative implant alignment intraoperatively. HipNav technology is used to gauge current clinical practice and provide intraoperative feedback to surgeons with the goal of improving the precision and accuracy of acetabular alignment during total hip replacement. This system provides surgeons with a new class of image guided measurement tools and assist devices. These tools successfully were introduced into the clinical practice of surgery with results showing the following: (1) There exist unpredictable and large variations in the initial position of patients' pelves on the operating room table and significant pelvic movement during surgery and during intraoperative range of motion testing; (2) current mechanical acetabular alignment guides do not account for these variations, and result in variable and in the majority of cases unacceptable acetabular alignment; and (3) press fitting oversized acetabular components influences the final cup orientation.