A previous arthroscopy raises infection risk after arthroplasty — at the knee and shoulder, not the hip

Design

systematic review and meta-analysis of 31 observational studies using a generalised linear mixed model, four databases searched to August 2025, subgroup analysis by joint

Population

patients undergoing knee, hip or shoulder arthroplasty with or without a history of prior arthroscopic surgery on that joint

Primary outcome

odds of overall and deep postoperative infection after arthroplasty

Effect

overall infection OR 1.33 (95% CI 1.14-1.56), deep infection OR 1.38 (1.17-1.63); raised at knee and shoulder, no significant association at hip; pooled infection rates 2%

Patients frequently arrive for arthroplasty having had an arthroscopy on the same joint years earlier, and it is usually treated as historical rather than as a risk factor. This meta-analysis of 31 observational studies, searched to August 2025 and pooled with a generalised linear mixed model, found otherwise.

Prior arthroscopy raised the odds of any postoperative infection after arthroplasty (OR 1.33, 95% CI 1.14 to 1.56) and of deep infection specifically (OR 1.38, 95% CI 1.17 to 1.63). The joint-specific breakdown is what makes this usable rather than merely interesting: prior knee arthroscopy was associated with raised infection risk, prior shoulder arthroscopy markedly raised the risk of deep infection, and hip arthroscopy showed no significant association at all. Pooled overall and deep infection rates in this population were both 2%.

Three things follow. Ask about previous arthroscopy explicitly and record which joint and when, because the history is often absent from the referral. Include it in the consent conversation for knee and shoulder arthroplasty, at the right magnitude — a relative increase of about a third on a 2% baseline, not a transformation of the risk. And do not extend the caution to the hip, where the association was absent. The evidence is entirely observational and the authors flag heterogeneity across joints plus a need for further shoulder-specific work, so this justifies attention and consent wording rather than a change in prophylaxis protocol.

• Ask about previous arthroscopy on the index joint and record which joint and when
• Include the raised infection risk in consent for knee and shoulder arthroplasty
• Do not apply the same caution to hip arthroplasty — no significant association was found
• Quote it proportionately: about a third higher odds on a 2% baseline rate
• Observational pooling with heterogeneity between joints; not a basis for changing antibiotic prophylaxis

The statistics, in plain English

An odds ratio of 1.38 against a 2% baseline means roughly 2.8% rather than 2% — a real increase but a small absolute one, and quoting the relative figure alone would frighten a patient out of proportion. The intervals (1.14 to 1.56 and 1.17 to 1.63) exclude 1.0, so the overall association is unlikely to be chance, but pooled observational studies cannot separate the arthroscopy itself from whatever made the joint need arthroscopy in the first place. The joint-specific findings rest on subgroups of the 31 studies and are correspondingly less certain than the overall estimate — which is precisely why the authors ask for more shoulder data.

Read the rest in the app

You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.

Get Daily Doctor — free

Scan to keep reading on your phone. No account needed to start.