Robotic medial UKA was more accurate with faster early recovery, but two-year Oxford scores were no different

Design

Double-blind randomised trial, interim analysis

Population

107 patients with medial compartment knee osteoarthritis

Primary outcome

Component position accuracy, early function and PROMs to 2 years

Effect

Better accuracy (p<0.001), shorter stay (p=0.004); Oxford Knee Score at 2 years p=0.299

This double-blind randomised trial reports interim results for 107 patients with medial compartment knee osteoarthritis allocated to conventional jig-based unicompartmental knee arthroplasty (UKA) with navigation (52) or robotic arm-assisted UKA (55). Both groups had CT planning and the same rehabilitation.

Robotic surgery achieved the planned femoral and tibial component positions more accurately (both p<0.001), with lower inpatient pain, less opioid use (p=0.008) and a shorter stay (p=0.004). At two years, Oxford Knee Score, KOOS and WOMAC did not differ. Forgotten Joint Score was higher with robotic surgery at six months and two years.

The case for robotic UKA has rested on accuracy and the hope that it translates into survival and function. This trial confirms the accuracy and early recovery gains, but the main functional scores had converged by two years.

Recruitment slowed as patients asked for the robot and surgeons lost equipoise, which is a warning about how hard definitive trials will be.

• Tell patients the robotic advantage is mainly earlier comfort and a shorter stay, not better function at two years.
• Long-term revision data, where accuracy should matter most, are still awaited.
• Weigh the added cost and theatre time against early recovery benefits in your setting.
• Record component alignment so accuracy can be linked to survival in registries.

Why it matters

Accuracy and early recovery have been confirmed, but the functional payoff that would justify the cost is not yet shown.

Don't overread it

These are interim results from a trial that did not reach its planned recruitment, and effect sizes for most outcomes were reported only as p-values.

The statistics, in plain English

A p-value says a difference is unlikely to be chance, not how large it is. Without effect sizes for pain, stay and Forgotten Joint Score, readers cannot judge whether the differences are clinically meaningful.

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