Robotic Partial Knee Replacement

What is Robotic Partial Knee Replacement

It is the replacement of a part of the knee with the assistance of a robot.

The Inner (medial), outer (lateral), front (patellofemoral) parts can all be replaced individually. Rarely a surgeon may want to replace 2 of the 3 parts at the same time (Bi-compartmental replacement).

How long has robotics been used to partial knee replacement

The first robotic partial knee replacement was performed in June 2006. Since then more than 50,000 procedures have been performed around the world. In Australia over 1000 procedures have been performed since its introduction in 2015. MHK surgeons first performed robotic Partial Knee replacements in 2016.

What is the revision (Redo) rate?

In 2017 the Australian Orthopaedic Associations National Joint Replacement Registry showed a 1-year revision rate of the MAKO partial knee replacement to be 0.8% which is the lowest of all listed prosthesis. The average for all partial knee prosthesis was 2.2%.

This is in keeping with previously published data for the Mako from the USA showing a 1.0% 2-year revision rate. When looking at traditional manual techniques in selected studies from specialist centers’ the 10-year revision rate for partial knee replacement may be as low as 2%.

There are is no long term data on survivorship of this procedure using a robot.

How is the operation planned?

The patients’ bony anatomy is registered during the operation which allows matching of the implant to the patients’ personal anatomy.

How is the operation performed?

Small metal pins are attached to the leg and “trackers” or “arrays” will then tell the sensor where the leg is and when it is moved.

The patients’ anatomy is then checked and a series of points are registered to ensure the anatomy is matched to the CT scan.

The knee is then put through a series of movements and the tension in the ligaments is measured and the movement of the knee is observed and the contact points between the components recorded. This produces a graph of the knee and a 3D model of how the knee will work after the replacement. The surgeon can then adjust the planned component position to change any aspect of the plan they want to improve.

Once the plan is set the bone model is shown with an area highlighted in green which is the bone to be removed. The bur is then used by the surgeon to remove the bone but the robot doesn’t allow the bur to move outside of the plan making this a highly accurate procedure.

Is this a “less invasive operation”

While the main cut used may be slightly smaller than a standard operation there is no significant difference in wound size.

Is it more accurate

There have been studies which show improved accuracy using robotic for partial knee replacement. We hope that improved accuracy will lead to better outcomes for patients.

Our results with conventional partial knee replacements have been excellent, and because the non-robotic partial knee replacement has a 30-year track record, we are using robotic surgery for some, but not all, of our partial knee replacements.

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