Major Study Finds Robotic Hip and Knee Surgery Offers No Early Surgical Advantage

Two large studies published this week in the BMJ have delivered an uncomfortable finding for the NHS at a moment when the health service is preparing to dramatically expand its use of robotic surgery: the technology does not appear to reduce the need for repeat operations in the years immediately following hip and knee replacement.

Researchers from Queen Mary University of London, the University of Oxford, and the University of Bristol analyzed data on more than one million joint replacements recorded in the National Joint Registry between 2018 and 2024. The scale of the analysis—the largest real-world evaluation of its kind—lends weight to a conclusion that challenges the premise underlying rapid adoption of robotic-assisted procedures. Despite the precision that robotic systems are designed to provide, that precision has not translated into fewer patients returning to the operating room for complications or failures in the early years after surgery.

Robotic hip and knee replacement works by keeping the surgeon in control while computer guidance and robotic assistance help plan and execute the placement of implants with greater technical accuracy. The theory is sound: better positioning should mean fewer problems down the line, both in the short term and over decades. The hip study did find one specific benefit—robotic assistance reduced the risk of surgery needed to correct problems caused by implant malpositioning. But this narrow advantage did not cascade into an overall reduction in repeat surgery rates. The knee study found no meaningful differences at all between robotic and conventional approaches.

The timing of these findings matters because the NHS is in the midst of planning a major expansion of robotic surgery, aiming to increase the number of procedures sevenfold by 2035. Each robotic system costs approximately one million pounds to acquire and install. Each procedure performed with robotic assistance adds between one thousand and twenty-five hundred pounds to the cost of surgery. Those are substantial investments, and they rest on the assumption that the technology delivers measurable benefit to patients.

Hasan Mohammad, an academic clinical lecturer in trauma and orthopaedics at Queen Mary and the lead author of the study, framed the research as providing "important independent evidence for patients, surgeons and policymakers at a time when robotic hip and knee replacement surgery is being adopted rapidly." His statement carried an implicit challenge: new technology should deliver meaningful benefit for patients and represent good value for a publicly funded health service. The evidence, at least in the early years after surgery, suggests this technology may not meet that standard.

The researchers used a statistical method called target trial emulation to analyze the registry data, a technique designed to make comparisons between groups resemble those of a clinical trial by accounting for differences in patient characteristics. This approach strengthens confidence in the findings. What remains unknown is whether differences in implant survival and long-term outcomes will emerge as patients are followed over many years. The studies examined early outcomes only. Longer-term follow-up will be necessary to determine whether the precision of robotic placement eventually translates into better durability or function. For now, policymakers face a decision: whether to proceed with a sevenfold expansion of a technology whose early benefits remain unproven, or to wait for evidence that might justify the cost.