Imageless computer-assisted navigation for total hip arthroplasty

Abstract

The introduction of computer-assisted surgery is an important landmark in the history of orthopedics. Its clinical use for total hip arthroplasty is recent. It can be image-based or imageless depending on the registration technique used: whether imageless or based on preoperative/intraoperative radiological images. It has changed the way surgeons perceive procedures. In this chapter, we describe an imageless method of computer navigation. It guides the surgeon through the various surgical steps that the surgeon could only speculate about previously. With this system, the surgeon sees the operation on a monitor in real time. It helps not only with acetabular orientation; it shows the cup's center shift at the time of reaming and cup insertion. Similarly, it can show femoral stem orientation and the changes it will make in leg length and its offset, thereby helping with final selection of the prosthesis. Its accuracy and precision have been reported by many to be > 95% regarding cup orientation, offset, and leg-length reproducibility. There is, however, a learning curve. The initial cases take more time to complete, but with experience, the operating time is lengthened by only 5-10 min. The instrumentation and technique could (and no doubt will) be improved. Even now, however, it has allowed more accurate and reproducible surgery. The preoperative plan can be executed with unprecedented accuracy compared with that achieved using conventional techniques.