Computer Guided/Computer Assisted Knee Surgery (CAS)

In computer-guided or computer-assisted robotic knee replacement surgery, special trackers are placed around the patient’s knee and signals are picked up by a sensor which then relays information to a computer which guides the bone cuts and other parts of the knee surgery. We currently reserve this technique for special cases in which conventional methods are not suitable for performing the knee replacement (eg. cases in which there is severe deformity above or below the knee or cases in which there was previous surgery with large amounts of metal hardware left around the knee).

knee surgery

knee surgery

knee surgery


Knee Surgery

Most recently, a new innovation in computer-guided (CAS) knee surgery has been introduced by Zimmer Inc (one of the largest orthopaedic implant companies in the world and Dr Lee is a consultant for them). It uses a wifi-enabled gyroscope tool and is called the iASSIST. The gyroscope technology is currently used in various “self-righting” applications (cell phones, video game controllers, etc.) and in the iASSIST, it potentially allows surgeons to position knee implants at the perfect angle and orientation.

knee surgery equipment


It consists of two main parts:

  1. The tool itself which contains the gyroscope and a wifi transmitter and
  2. An LED panel that receives and interprets the location of the tool.

The iASSIST represents a next step in surgical guidance, providing simple, intuitive and accurate intraoperative feedback and alignment validation to surgeons during joint replacement procedures, eliminating the need for bulky capital equipment. Current robotic and navigation systems use optical-tracking, requiring a clear line-of-sight into the surgical field, and rely upon complex additional equipment in the operating room, providing feedback on external computer screens.

Zimmer’s iASSIST technology comprises small electronic disposable pod components that are used at the site of knee replacement surgery, providing instantaneous, accurate alignment validation through a simple electronic display. The disposable pods are manipulated within the surgical field with positioning information provided by a series of internal accelerometers. iASSIST Knee does not require the use of pins or additional incisions and does not rely on external systems or stimulus.