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Tomasz Poboży

Single-stage or two-stage revision for hip prosthetic joint infection?

Autor:

Tomasz Poboży

Polish version: Jednoetapowa czy dwuetapowa rewizja zakażonej endoprotezy biodra?

An analysis of 754 patients with hip prosthetic joint infection found no significant functional difference at 18 months between planned single-stage and two-stage revision. Single-stage revision showed earlier improvement at 3 months, which subsequently diminished. The findings do not establish equivalence or simplify patient selection.

Why this study matters to an orthopaedic surgeon

Single-stage revision combines implant removal, thorough debridement and reimplantation in one operation, avoiding an interval without definitive reconstruction. Suitability depends on the patient, organism, soft tissues and bone. The INFORM randomized trial, published in BMJ in 2022, found no functional superiority at 18 months but faster early recovery after single-stage treatment. Zhang and colleagues’ study, published on 6 September 2026, examined whether a larger routine-care population showed a similar pattern.

Study design

The retrospective analysis used data from three specialist centres in China and a target trial emulation framework, structuring observational data to resemble an ideal randomized comparison. It included 754 adults treated from January 2018 to June 2022: 280 with a planned single-stage strategy and 474 with two-stage revision using a temporary antibiotic spacer.

Allocation reflected the documented preoperative plan. Intraoperative conversions remained in the originally intended group. The primary outcome was Harris Hip Score (HHS) at 18 months; surgically treated reinfection, reoperation, mortality and complications were also assessed. Inverse probability weighting used 32 variables, with an additional analysis of 280 matched pairs.

This was not randomization. Clinicians selected treatment, and factors including soft-tissue quality, bone defects, surgeon experience and adequacy of debridement could not all be incorporated into the model.

Main results

  • Adjusted HHS difference at 18 months: 1.68 points favouring single-stage revision (95% CI −0.12 to 3.48; P = 0.07).
  • Matched-pair analysis: difference 1.98 points (95% CI −0.25 to 4.21; P = 0.08).
  • At 3 months, HHS favoured single-stage revision by 5.82 points (95% CI 1.43–10.21; P = 0.01); the difference later diminished.
  • Surgically treated reinfection occurred in 13.2% versus 11.8%: RR 1.12 (95% CI 0.72–1.74).
  • Mortality did not differ significantly: 2.9% versus 4.0%.
  • Sensitivity analyses retained the same direction, with HHS estimates ranging from 1.18 to 2.48 points.

Interpreting early recovery

At 3 months, many two-stage patients may still have a spacer and be awaiting definitive reconstruction. The comparison therefore captures the burden of the two-stage pathway as well as any biological effect. Likewise, fewer recorded intraoperative events after one stage must be interpreted against one operative exposure versus two; this does not prove the individual single-stage procedure is inherently safer.

Comparison with INFORM

The pattern is consistent with INFORM: similar primary function at 18 months and better early function at 3 months after single-stage treatment. A larger observational cohort in another healthcare setting adds context but does not replace randomization. INFORM used WOMAC, while this study used HHS, so their numerical differences are not directly comparable.

Limitations

  • Unmeasured treatment-selection factors remain possible without randomization.
  • Soft tissues, bone loss, adequacy of debridement and surgeon experience were not fully modelled.
  • Adding hospital and surgeon to the model reduced the HHS difference, suggesting a team or centre contribution.
  • Some missing HHS values among survivors required multiple imputation.
  • Functional analysis concerned patients alive at each assessment; function cannot be defined after death.
  • No equivalence or noninferiority margin was prespecified, so nonsignificance does not establish equivalence.
  • The protocol and analysis plan were not prospectively registered before access to outcome data.
  • Three referral centres may not represent less experienced services.

Implications for practice

Single-stage revision can be a reasonable option for carefully selected patients managed by experienced teams. The study found no clear signal of worse 18-month function or more surgically treated recurrence, while avoiding the interval between operations. It does not define selection criteria by organism, soft tissue, bone loss or host status, establish superior infection control, or justify abandoning two-stage revision when clinically indicated. Decisions remain specific to the infection and reconstructive circumstances.

References

  1. Zhang C, Li Y, Su C, Shen Y, Lu S. Comparative effectiveness of single-stage versus two-stage revision for hip prosthetic joint infection: emulation of the INFORM target trial using electronic health record data. Arch Orthop Trauma Surg. 2026;146:327. DOI: 10.1007/s00402-026-06503-0.
  2. Blom AW, Lenguerrand E, Strange S, et al. Clinical and cost effectiveness of single stage compared with two stage revision for hip prosthetic joint infection (INFORM): pragmatic, parallel group, open label, randomised controlled trial. BMJ. 2022;379:e071281. DOI: 10.1136/bmj-2022-071281. PMID: 36316046.

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Content prepared by: Tomasz Poboży - orthopaedic surgeon.

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