Robotic knee replacement: no functional advantage, longer operations

Design

Meta-analysis of randomised controlled trials only (24 trials), with meta-regression and GRADE

Population

3,425 patients undergoing total knee arthroplasty

Primary outcome

Function (WOMAC, Knee Society, Oxford Knee scores), pain and perioperative outcomes

Effect

No significant differences (WOMAC MD 0.14, 95% CI -5.88 to 6.16); operative time about 22 minutes longer

Robotic-assisted total knee arthroplasty is marketed on precision, but whether that translates into better outcomes has been muddied by pooling trials with observational data. This meta-analysis used randomised trials only, 24 of them covering 3,425 patients, with GRADE assessment of certainty.

Across the board there was no significant difference from conventional surgery: WOMAC function (mean difference 0.14, 95% CI -5.88 to 6.16), functional Knee Society Score (0.51, -3.43 to 4.44) and Oxford Knee Score (2.07, -6.82 to 10.96) were all flat, as were pain, range of motion, satisfaction and hospital stay. A six-month Oxford Knee Score signal did not reach the minimal clinically important difference and was not sustained. Operative time was about 22 minutes longer with the robot, though with extreme heterogeneity and a likely learning-curve effect. Certainty was low to very low throughout.

The practical message is sober. On current randomised evidence robotic knee replacement does not deliver better function or pain than conventional surgery and takes longer, so the case for routine adoption, and for the capital and running costs it carries, is not yet made.

• Randomised-only meta-analysis: 24 trials, 3,425 patients, GRADE-assessed.
• No significant difference in WOMAC, Knee Society or Oxford Knee scores, pain, range of motion or hospital stay.
• A 6-month Oxford Knee Score signal fell below the minimal clinically important difference and was not sustained.
• Operative time was about 22 minutes longer with the robot.
• Weigh the capital and running cost of robotic systems against an absence of functional benefit.

Why it matters

It challenges the assumption that robotic precision buys better knees, which bears directly on large purchasing and marketing decisions.

Don't overread it

Low-to-very-low certainty means absence of a measured benefit is not proof of true equivalence; this analysis does not address implant longevity or revision rates over the long term.

The statistics, in plain English

Every functional confidence interval comfortably crosses zero, meaning no detectable difference; the single positive subgroup was below the threshold patients can feel, and the low-to-very-low certainty means even these null estimates could shift with better trials.

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