Positioning Device Helps Surgeons Accurately Place Knee Implants

A novel personalized guidance system (PGS) for knee replacements uses disposable accelerometers to relay positioning information to the physician.

The Zimmer iASSIST Knee PGS is a computer assisted stereotaxic surgical instrument system with a simple electronic display that is used to determine alignment axes in relation to anatomical landmarks, and to precisely position implant components relative to those axes during joint replacement procedures. The disposable pods are manipulated within the surgical field with positioning information provided by a series of internal accelerometers, does not require the use of fixation pins or additional incisions, and does not rely on external systems or stimulus.


The accelerometer and gyroscope-based inertial sensors are assembled or combined with manual surgical instruments to provide navigation information for the manual placement of orthopedic implants intra-operatively by providing the navigation information for the precise placement of femoral and tibial culling planes for knee replacement surgery. The Zimmer iASSIST Knee PGS is a product of Zimmer (Warsaw, IN, USA), and has been approved by the US Food and Drug Administration (FDA).

“iASSIST Knee represents the next-step in intelligent instruments, offering significant benefits to patients, health care providers and health systems,” said Jeff McCaulley, President of Zimmer Reconstructive. “We are greatly excited by the potential of iASSIST technology, which delivers on the promise of accurate implant positioning and alignment validation without the complexity, cost and time associated with current capital-intensive navigation and robotic systems.”

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 to provide feedback onto external computer screens.

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