With local antibiotics, a short systemic course held up in bone infection

Design

Multicentre, open-label, randomised noninferiority trial (margin 10 points)

Population

500 adults after surgery for orthopaedic infection with a local-antibiotic carrier

Primary outcome

Definite treatment failure by 12 months

Effect

Failure 11.1% (short) vs 14.1% (long); risk difference -3.0 points (95% CI -9.0 to 3.0)

SOLARIO, a multicentre open-label noninferiority trial, randomised 500 adults who had surgery for orthopaedic infection and implantation of a local-antibiotic carrier to a short (7 days or less) or long (4 weeks or more) systemic antibiotic course, with definite treatment failure by 12 months as the primary outcome and a 10-percentage-point noninferiority margin.

Failure occurred in 11.1% of the short-course group and 14.1% of the long-course group (risk difference -3.0 points, 95% CI -9.0 to 3.0), meeting noninferiority. By six weeks, treatment-related symptoms were far less common with the short course (17.2% vs 45.2%, a 28-point difference).

The practical message is specific but real: where surgery includes a local-antibiotic carrier, a week or less of systemic antibiotics worked as well as a month or more and caused far fewer side effects. It is not a licence to shorten systemic antibiotics in orthopaedic infection generally, since the short arm depended on local delivery at operation.

• With a local-antibiotic carrier implanted, a 7-day or shorter systemic course was noninferior to 4 weeks or more.
• Treatment failure was 11.1% (short) versus 14.1% (long) at 12 months.
• Treatment-related symptoms were far fewer with the short course (17.2% vs 45.2% by week 6).
• The benefit depends on local antibiotic delivery at surgery, not short systemic courses alone.
• Discuss shorter systemic duration with the surgical and infection teams when a carrier is used.

Why it matters

It challenges the default of weeks of systemic antibiotics after bone-infection surgery when local antibiotics are used.

Don't overread it

This applies only where a local-antibiotic carrier was implanted; it does not justify shortening systemic antibiotics in orthopaedic infection generally.

The statistics, in plain English

Noninferiority means the short course was not meaningfully worse within a pre-set 10-point margin; the confidence interval (-9.0 to 3.0) stays within it, and the large drop in side effects favours the short course.

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