In brief

Systematic reviews generally find more reproducible acetabular component positioning with robotic-assisted than manual THA.
Inclination, anteversion, centre of rotation, leg length, and offset are distinct outcomes; improvement in one does not imply improvement in all.
A “safe zone” is a research range, not a universal guarantee against dislocation.
Better positioning evidence must not automatically become a promise of better function, fewer dislocations, or fewer revisions.

Clinical question

Population: adults undergoing primary total hip arthroplasty (THA). Intervention: robotic-assisted planning and execution. Comparator: manual technique or other navigation technologies. Outcomes: deviation from plan, component angles, proportion within a target range, leg-length restoration, and offset.

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

What is measured

Cup position is commonly described by inclination and anteversion. Studies may also assess stem position, leg-length discrepancy, global offset, and deviation between achieved position and preoperative plan. Values depend on coordinate system, pelvic position, imaging method, and timing.

The Lewinnek range is often used to classify cup position, but it does not capture all individual anatomy or dynamic pelvic behaviour. Being inside it does not guarantee freedom from dislocation; being outside it does not make a complication inevitable.

Available evidence

A meta-analysis of 38 comparative studies (10,055 patients) assessed radiographic, clinical, perioperative, complication, and revision outcomes for robotic-assisted and manual THA [1]. It reported greater placement accuracy without superior clinical results. Pooling heterogeneous observational studies limits certainty.

A systematic review of 25 prospective comparative studies covering 52 intraoperative techniques found computerized navigation consistently more accurate and precise, but heterogeneity precluded meta-analysis and evidence was insufficient for clinical or cost conclusions [2]. This concerns a broad technology class, not every individual robot.

A network meta-analysis of randomized studies compared manual, robotic, computer-navigated, and other methods for implant placement accuracy [3]. Indirect comparisons help map evidence but rely on comparability of populations, approaches, and endpoint definitions.

A meta-analysis restricted to randomized trials separately assessed clinical, functional, and radiological outcomes of robotic-assisted and conventional THA [4]. Randomization reduces confounding, but study count, platforms, and follow-up still limit conclusions about uncommon events.

Findings

The direction of evidence supports more reproducible achievement of selected planned and radiographic parameters with robotic-assisted THA. The number and quality of studies do not support treating one target range as universal or ranking every platform.

Limitations

Robotic platforms, generations, surgical approaches, and imaging methods differ.
Pelvic position may differ between preoperative and postoperative assessment.
Targets and outlier definitions are inconsistent.
Much evidence is observational; selection bias, learning curves, and industry relationships may apply.
Dislocation and revision are uncommon, and positioning studies are usually underpowered for them.

Interpretation

Positioning is one technical part of THA. Clinical outcome also reflects anatomy, soft tissues, implant, approach, team experience, and rehabilitation. Claims of fewer dislocations or revisions require direct evidence with adequate sample size and follow-up—not only smaller angular deviation.

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.