SINGAPORE – Robot-assisted total knee arthroplasty, or knee replacement surgery, has grown in popularity worldwide due to its greater precision and improved outcomes, but it also risks complications such as fractures.

This is because up to four tracker pins are drilled into the thigh and shin bones to enable the robot to map the bones precisely in real time and guide the surgeon. Inserting pins at multiple points can weaken the bones, making them more likely to fracture.

Other risks include wound infections and nerve injuries, noted Adjunct Assistant Professor Glen Liau, a consultant at Alexandra Hospital’s orthopaedic surgery department.

To reduce these risks, a team led by Prof Liau developed a tool known as a jig, which is less invasive than the conventional method.

The tool requires just a single incision on the knee through which all the pins are drilled. This lowers the risk of bone fracture, bleeding and infection associated with additional cuts.

“In addition, the surgical grade stainless steel jig enables precise control of pin depth and angle, ensuring consistent and accurate placement,” said Prof Liau.

While surgeons typically select the points of incision by eye, Prof Liau identified a specific position – now called the Liau inflection point – that can be used consistently for every patient to guide pins to the exact locations.

This method eliminates estimation, allowing the surgeon to insert the pins with precision, accurate to within 1mm and one degree.

“With this accuracy, we have also been able to shorten our main central incision, making our operations even more minimally invasive,” he said.

Laboratory tests showed that the traditional method caused fractures 80 per cent of the time, compared with only 30 per cent using the new method.

The procedure was validated in a study of 102 patients using major robotic total knee arthroplasty systems, with the findings publishe...