Articulating versus static antibiotic-loaded hip spacers in two-stage revision for hip periprosthetic joint infection in inflammatory rheumatic disease: a retrospective cohort study (2008–2023)

We conducted a single-center retrospective observational cohort study at a tertiary referral center. The study period spanned January 2008 to December 2023, and eligible cases were identified through the institutional database.
We included patients with hip PJI who required revision surgery consisting of implant removal and placement of an antibiotic-loaded cement spacer as part of a two-stage revision strategy. Patients were categorized into two groups: articulating hip spacers (Group 1) and static hip spacers (Group 2). After confirming hip PJI in both groups using international clinical and laboratory standards, acetabular and femoral loosening were documented radiographically in all patients using the Gruen and DeLee zones, consistent with septic loosening. Primary outcomes were functional recovery and pain, assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Harris Hip Score (HHS), and the Numeric Pain Rating Scale (NPRS). Secondary outcomes included hip range of motion (ROM), intraoperative blood loss, operative time at each surgical stage, microbiological profile, and clinically relevant failure patterns (e.g., unplanned surgery, spacer-related complications, inability to proceed to reimplantation, or salvage procedures).
Given the retrospective design and non-randomized spacer selection, this study is susceptible to selection and information bias. To reduce selection bias, we included all consecutive eligible patients treated during the study period. To reduce information bias, we used routinely collected standardized functional scores and objective perioperative data documented in the institutional database and medical records.
No formal sample size calculation was performed; the cohort includes all eligible cases treated with two-stage revision and hip spacer implantation during the study period. Analyses were conducted using complete-case data. When denominators differed due to missing documentation, the corresponding denominators (n/N) are reported.
Data Analyses: The data collected in our research were analyzed using IBM SPSS Statistics (IBM Corp., Armonk, NY, USA). Continuous variables were summarized as mean ± standard deviation or median (interquartile range), as appropriate. Between-group comparisons were performed using the independent-samples Student’s t-test for normally distributed variables and the Mann–Whitney U test for non-normally distributed variables. Categorical variables were compared using the Chi-square test or Fisher’s exact test, as appropriate. A P-value < 0.05 was considered statistically significant. No multivariable adjustment for confounding was performed, given the sample size; all between-group comparisons are unadjusted. Loss to follow-up was addressed by using the last available documented assessment; analyses were performed on complete cases for each outcome. No formal sensitivity analyses were conducted.