Robotic assisted hip and knee replacements shows no clear benefit over conventional methods

The NHS recently outlined plans to expand robotic surgery sevenfold by 2035, but initial findings from the first UK big data studies on this topic published by The BMJ suggest that robotic assisted hip and knee replacements offer no clear benefit over conventional surgery for implant survival, revision risk, or surgical complications. 

Given the significant expense associated with robotic surgery (around £1m in upfront costs plus an extra £1,000-2,500 per patient) the results question the 10 year NHS plan for widespread adoption of robotics for hip and knee replacements. 

Robotic surgery involves doctors using computer-controlled robotic arms and high-definition cameras to assist them with complex procedures. 

Studies have shown that robotic assisted hip and knee replacement surgery improves implant placement – potentially reducing the need for further revision surgery – but it’s still unclear if this leads to better clinical outcomes and reduced revision risk. 

The National Institute for Health and Care Excellence has therefore called for urgent research into the effect of robotic surgery on revision risk after joint replacement. 

So researchers analyzed data from the National Joint Registry for 666,283 total hip replacements (656,080 conventional and 10,203 robotic) and 697,145 total or partial knee replacements (675,034 conventional and 22,111 robotic) performed between 2018 and 2024 in public and private hospitals across the UK.

They used a statistical technique called propensity score matching to balance out underlying differences between patients having conventional or robotic surgery, allowing them to draw more reliable conclusions. Other potentially influential factors, such as age, sex, body mass index, diagnosis, physical fitness, implant type and surgeon volume were also taken into account.

They then compared a range of outcomes including implant survival, patient survival, reasons for revision and complications during surgery for an average of 2.5 years after surgery.

The results show no differences in implant survival, or overall or cause-specific revision risk and complications during surgery between conventional and robotic hip and knee replacement groups. Nor was there any difference in patient survival between conventional and robotic hip replacement groups.

Robotic surgery was, however, associated with a lower risk of hip revisions that may be related to implant malpositioning than conventional surgery.

These are observational studies, so no firm conclusions can be drawn about cause and effect. The authors also acknowledge that other unmeasured factors could have affected their findings and note that the limited follow-up period may mask longer term outcomes.

Additional research is needed to compare patient functional outcomes between groups which will be answered in due course by the ongoing RACER clinical trials. 

However, they point out that target trial emulation is one of the most robust methods for analysing observational data, providing vital insights to help commissioners plan care.

As such, they conclude: “These results highlight the importance of careful evaluation of robotic technology in publicly funded healthcare systems, given the substantially higher capital and procedural costs involved.”