In brief

Across studies, robotic-assisted TKA more often reproduces selected technical targets and reduces some radiographic outliers.
Effects depend on the platform, comparator, alignment strategy, and measurement method.
Accuracy relative to a plan is not the same as an “ideal” position for every patient.
These data alone do not establish less pain, fewer complications, or longer implant survival.

Clinical question

Population: adults undergoing primary total knee arthroplasty (TKA). Intervention: robotic-assisted TKA. Comparator: conventional manual instrumentation or navigation. Outcomes: deviation of resections and components from plan, alignment deviation, and the proportion beyond a predefined threshold.

The search for this version was updated on 8 August 2026.

What “accuracy” means

Studies use different targets: resection thickness in millimetres, component angles, the hip–knee–ankle angle, or a range commonly set at ±3°. Accuracy is closeness to target, precision is the spread of repeated results, and an outlier falls beyond a stated boundary. Changing that boundary changes the outlier rate, so percentages from unrelated studies should not be ranked directly.

Available evidence

A meta-analysis of 21 randomized trials (2,692 participants) reported fewer mechanical-alignment outliers with robotic-assisted TKA (RR 0.33, 95% CI 0.19–0.59) and a mean 0.93° smaller deviation from neutral mechanical alignment [1]. The pooled result spans platforms and device generations and does not establish superiority of an individual robot.

Platform studies answer narrower questions. In a prospective single-centre MAKO series, 52 of 55 measured cases had resection deviation below 1 mm; there was no control group [2]. In an early retrospective imageless ROSA series, no robotic case among 71 was more than ±3° from plan, compared with 24% among 308 conventional TKAs [3]. Confounding and a learning-curve effect remain possible.

A CUVIS cadaveric study used 3 specimens (6 knees) to assess angular and resection-thickness accuracy [4]. A paired VELYS cadaveric study of 40 specimens and five surgeons found smaller errors for several angular parameters and fewer >3° outliers, with equivalent results for other parameters [5]. It was partly funded by DePuy Synthes. Cadaveric findings are not patient outcomes.

Findings

Evidence supports more reproducible execution of selected planned and radiographic parameters with robotic-assisted rather than conventional instrumentation. Confidence is stronger in the overall direction than in numerical comparisons among systems. Platforms should not be treated as interchangeable.

Limitations

There is no universal target alignment or outlier definition.
A plan may use mechanical, kinematic, or functional alignment; deviation from neutral is not always an error.
Radiographs, CT, and system logs measure different quantities and each has measurement error.
Many platform studies are small, single-centre, retrospective, or cadaveric.
Surgeon experience, software version, implant, and postoperative measurement affect transferability.

Interpretation

Technical accuracy describes how consistently a selected plan is executed. Whether that plan is appropriate for an individual remains a clinical decision. PROMs, complications, revisions, and survivorship must be examined separately before making patient-benefit claims.

References

This review reflects the evidence available as of the stated search date. Studies may differ in systems, versions, populations, methods, and follow-up. Research findings cannot predict an individual outcome and do not replace a discussion of treatment options with a healthcare professional.