Robotic total hip arthroplasty narrowed leg-length discrepancy by about 2 mm

Design

Systematic review and meta-analysis of 7 comparative studies, mostly non-randomised

Population

968 patients undergoing robot-assisted or conventional THA

Primary outcome

Leg-length discrepancy, cup orientation, early hip scores

Effect

LLD −2.02 mm (−3.46 to −0.58); Harris Hip Score +2.96 (1.12–4.80)

This meta-analysis included seven comparative studies with 968 patients, most of them non-randomised, comparing robot-assisted with conventional total hip arthroplasty.

Robotic assistance gave a smaller postoperative leg-length discrepancy (mean difference −2.02 mm, 95% CI −3.46 to −0.58) and slightly lower cup anteversion (−1.52°), with no difference in cup inclination. Early function scores were higher: Harris Hip Score +2.96, Oxford Hip Score +2.61, and Forgotten Joint Score +14.68 (5.02–24.33).

The precision gain is consistent with the wider literature, but 2 mm of leg length and 3 points on the Harris score are below what most patients notice. Registry data have not shown better survivorship or fewer complications. For Indian centres weighing the capital cost, this does not change the case: robotic systems improve reproducibility, not yet outcomes that patients feel.

• Present robotic hip replacement to patients as a precision tool, not a proven route to better function
• Audit leg-length and cup position in your own conventional cases before assuming a robot is needed
• Look for long-term survivorship data before large capital decisions
• Keep careful preoperative templating whatever the technique

Why it matters

Robotic systems are being marketed on outcomes, and the measurable gains remain small and short-term.

Don't overread it

Mostly non-randomised studies with short follow-up — the functional score gains may reflect surgeon and patient selection.

The statistics, in plain English

A 2 mm mean reduction is statistically clear but below the threshold most patients perceive. The Forgotten Joint Score difference is larger but its wide interval (5 to 24 points) and the mostly non-randomised studies make it uncertain; surgeons adopting robots early may also differ in experience.

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