Robotic Knee Replacement Surgery

What is Robotic Knee Replacement Surgery?

To perform a knee replacement, the bone at the bottom end of the thigh bone (femur) and the top end of the shin bone (tibia) has to be cut and reshaped to fit the shape of the joint replacement parts (the prostheses). With conventional methods, rods and cutting blocks are positioned into or around the bones to help guide the surgeon where to cut the bones. This uses a “one size fits all approach” and can result in the soft tissue being too tight or too loose on one side of the knee compared to the other. The soft tissue on the tight side then has to be cut or loosened.

Robotics helps the surgeon to plan out the operation before any bone cuts are made and it can be used to adjust the position of the prostheses to take the soft tissue tightness into account.

What is the robot?

There are actually two parts to the robot system. There is a computer that is used to plan the procedure and control the robot. Then there is the robot itself, which is essentially a computer controlled cutting device that is guided by the surgeon. There are several robotic surgery systems available and Mr Wong has trained in the use of the two most popular ones and has been using them for almost all his joint replacements since the technology first became available in 2017.

How is a robotic knee replacement performed?

Temporary pins are placed into the femur and tibia and markers are attached to them. The computer has an infrared camera that monitors the position of the markers so that it knows exactly where the bones are during the operation.

A calibrated probe is then used to trace over the surface of the knee joint and the computer uses that information to create a detailed model of the patient’s knee.

The surgeon then plans the operation on the computer. The knee is moved through a full range of movement and the computer records how tight the soft tissue is on either side of the knee during this movement. The position of the prostheses is then planned using precise measurements of the bone. The position can then be adjusted to make sure that the soft tissue will not be too tight or too loose through the whole range of movement.

Once the plan is complete, it is then used to guide the robotic cutting tool. With the system that Mr Wong uses, there is a high-speed bur that is run over the surfaces of the knee. The computer controls the bur and will stop or retract it when appropriate so that only the bone that is supposed to be removed is burred away. This is an extremely precise method and it ensures that the bone is cut exactly the way it was planned.

Once the bone surfaces have been prepared, the knee replacement prostheses are then implanted. The knee is then taken through a range of movement again and the final product can be compared to the plan in the computer.

What are the advantages of robotic knee replacement?

Robotic knee replacement allows the positioning of the prostheses to be done in a way that is customised to the individual patient’s anatomy. This optimises position of the prostheses with respect to the shape of their bones and the tightness and laxity of the soft tissue around the knee. This results in a knee that is as stable and comfortable as possible.

The robotic cutting tool is very precise and results in the bones being cut exactly as planned. This makes the procedure very reliable and predictable. Because the bur can be guided more carefully than the conventional saw blade there is minimal damage to the surrounding soft tissue. Also, because there is no need to insert instruments into the bone, as is done in conventional surgery, there is less blood loss.

It is hoped that these factors result in a faster recovery and better outcomes in terms of how the knee feels and performs and how long it lasts.

Does it cost extra to have robotic surgery?

Mr Wong does not charge any extra fee to perform total knee replacements robotically.

Other relevant information

Mr Wong has been performing robotic total knee replacements since the technology became available in Australia in 2017 and is very happy with the results. Because of his experience in robotic surgery, Mr Wong has been invited to join a group of surgeons at multiple centres in four countries. They are conducting a large randomised control trial to compare patients who have knee replacements performed by conventional methods to those who undergo robotic surgery. The study will run for two years and will provide more information about the advantages robotic knee replacement has over conventional surgery.

Mr Wong is also part of a committee of well-respected international knee surgeons who give advice on the future development of the robotic knee replacement system.


  • Healthscope
  • Australian Medical Association
  • Healthecare
  • Royal Australasian College of Surgeons
  • Northern Health
  • Epworth HealthCare
  • University of Melbourne
  • Ramsay Health Care