- Design
- Randomised, double-blinded trial, interim analysis
- Population
- 107 patients with medial compartment knee osteoarthritis
- Primary outcome
- Component positioning accuracy and functional outcomes over 2 years
- Effect
- Better accuracy (p < 0.001) and shorter stay (p = 0.004); Oxford score p = 0.299 at 2 years
This interim report from a single-centre trial randomised 107 patients with medial compartment osteoarthritis to robotic arm-assisted or conventional jig-based unicompartmental knee arthroplasty, both with CT planning. Patients and assessors were blinded.
The robot placed femoral and tibial components closer to plan (both p < 0.001). Inpatient pain and opioid use were lower and stay shorter (p = 0.004). The Forgotten Joint Score was better at six months and two years. Oxford Knee Score, KOOS and WOMAC did not differ at two years.
Recruitment slowed as patients increasingly asked for the robot and surgeons lost equipoise, which is why this is an interim report. The early benefits are real but modest; whether accuracy translates into better survivorship needs longer follow-up.
- Counsel that robotic UKA may mean a smoother early recovery, not a better knee at two years.
- Do not promise longer implant survival yet — the trial has not reported it.
- Where a robot is not available, jig-based UKA with careful planning remains appropriate.
- Record Forgotten Joint Score alongside Oxford score in local audit.
Why it matters
It separates the early recovery benefit of robotic UKA from the functional outcome most patients care about at two years.
Don't overread it
This is an interim analysis of an under-recruited single-centre trial, with no survivorship data.
The statistics, in plain English
Multiple secondary outcomes were tested, and the abstract gives p-values without effect sizes, so the size of the pain and stay differences cannot be judged. A Forgotten Joint Score gain with no Oxford difference suggests the joint feels more natural, not that it works better.
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