Hofmann articulating spacer vs preformed cement spacer two stage revision in native septic knee arthritis: a comparative study

Purpose: Septic arthritis (SA) of the native knee is a severe and increasingly prevalent condition, particularly among elderly and comorbid patients. When associated with end-stage degenerative joint disease, a two-stage total knee arthroplasty (TKA) with an antibiotic-loaded articulating spacer is commonly adopted. However, evidence directly comparing different spacer designs is limited. The aim of this study was to compare the clinical and functional outcomes of two two-stage strategies: a preformed cement articulating spacer and a Hofmann-type metal-on-polyethylene articulating spacer. Methods: We retrospectively reviewed 15 consecutive patients treated between June 2022 and December 2024 at a tertiary referralcentre. Inclusion criteria were native knee SA with end-stage arthritis managed with planned two-stage TKA and minimum 12-month follow-up. Seven patients received a Hofmann spacer and eight a preformed cement spacer. The primary endpoint was septic failure, defined as recurrent infection requiring surgical intervention; secondary endpoints included functional outcomes (Knee Society Score [KSS], Oxford Knee Score [OKS], Forgotten Joint Score [FJS]), pain (VAS), and range of motion (ROM) during the interstage period and after reimplantation. Results: Mean follow-up was 24.2 months. Infection eradication was comparable between groups, with one reinfection (6.7%) occurring in the cement spacer group (p = 1). During the interstage period, the Hofmann group demonstrated significantly superior KSS, OKS, FJS, VAS, and ROM (p = 0.001). After reimplantation, functional outcomes remained significantly better in the Hofmann group, with greater ROM and higher patient-reported scores. Two patients in the Hofmann group elected spacer retention due to satisfactory function. Conclusion: Both strategies achieved effective infection control. However, the Hofmann articulating spacer provided superior functional recovery without compromising septic eradication, supporting its use in selected patients with native septic knee arthritis and advanced degeneration.