The time taken for a total knee replacement procedure could be cut by half, thanks to new technology developed by Alexandra Hospital.

An artificial intelligence (AI)-powered algorithm is integrated into a robot’s software to determine the optimal positioning of implants in a fraction of a second. Robots are commonly used to make the operation more precise.

Total knee replacement is among the most common procedures performed here, with about 6,000 such cases each year.

While the accurate positioning of implants is crucial to the success of the operation, deciding on the optimal placement is a complex process due to the unique bone and ligament structures of each patient.

Currently, this is done during the course of surgery, with surgeons manually planning and adjusting the positioning of the implants for the femur and tibia or thighbone and shinbone.

Manual planning is a time-consuming process that takes around 15 minutes in the operating theatre. Given time constraints, the surgeons are limited in their ability to explore possible solutions.

Dr Glen Liau, a consultant with Alexandra Hospital’s orthopaedic surgery department, said the planning cannot be done beforehand as current imaging – ranging from X-rays to computerised tomography and magnetic resonance imaging scans – fail to provide surgeons with details such as the full range of movement of a patient’s knee.

To address these issues, Dr Liau developed the algorithm with the aim of making robotic total knee replacement surgery more accurate and efficient, working with Dr Matthew Ng and Mr Ryan Loke, both medical students at the time. Dr Ng is currently a house officer at Singapore General Hospital, while Mr Loke is a final-year medical student.

The three of them, using their experience in coding and programming, were able to develop the algorithm within one week.

The algorithm can compute thousands of permutations to determine the optimal implant positioning, accurate to within 0.5mm, in under 0.1 second.

A prospective study of 67 patients who underwent robotic total knee replacements was conducted between November 2021 and December 2023, with 25 cases utilising the algorithm.

It found 92 per cent of the operations that used the algorithm were accurate to within 1.5mm.

Meanwhile, only 52 per cent of cases that did not use the algorithm had such accuracy.

The study also found that with the algorithm, planning during a procedure took about only one minute, while the process without it took more than 14 minutes.

This resulted in a shorter surgery time of about 38 minutes with the algorithm and more than 73 minutes without it.

Patients in the algorithm group reported higher satisfaction with their knee replacements due to better alignment and fewer complications.

Dr Liau told the media on Feb 10: “Results from our study show that this could potentially be a game changer, impacting the accuracy efficiency for all robotic total knee replacement operations in the future.”

He noted that the reduced surgery times could also result in other positive outcomes for the patients, such as a reduced risk of infection and less time spent under anaesthesia.

Further studies are currently being conducted to determine the effects of the algorithm.

In August 2024, the team filed an international Patent Cooperation Treaty, protecting its exclusivity and proprietary rights in 150 countries, after having filed a Singapore patent in October 2023.

The project was presented at the International Society for Technology in Arthroplasty congress in the US in 2024.

That year, it was awarded the P Balasubramaniam Young Orthopaedic Investigator’s Award in Singapore.

The team is currently in talks with various companies to commercialise the technology, Dr Liau said.

Since August 2023, about 200 patients have gone under the knife using this innovation.

Housewife Rita Sarswathi – who first experienced pain in her knees about three years ago – underwent surgery on her right knee in January 2024 and her left knee about two weeks ago.

The 73-year-old said she is now able to walk faster and for longer durations with “no pain at all”.

Retired ship repairman Wong Chee Meng, 73, who had surgery on his right knee in November 2023, was able to trek up mountains while on holiday in China’s Guizhou province in April 2024.

“After four months I was fully recovered,” said Mr Wong, who is scheduled for surgery on his left knee in January 2026.