HOFMANN ARTICULATING SPACER VERSUS PREFORMED CEMENT SPACER TWO-STAGE REVISION IN NATIVE SEPTIC KNEE ARTHRITIS: A COMPARATIVE STUDY

Background The treatment for native septic knee arthritis with joint degeneration is a two-stage revision using an antibiotic-loaded cement spacer. The 1.5-stage approach, well studied in periprosthetic joint infection, has gained interest because it allows functional articulation, earlier mobility, and may reduce the need for a second surgery. This study compares the outcomes of two-stage revision using either preformed cement spacers or Hofmann-type articulating spacer. The primary objective was to evaluate septic failure, while the secondary objective was to compare functional recovery between the two groups during the interstage period and after reimplantation. Materials and Methods We retrospectively reviewed patients who underwent two-stage revision surgery for septic knee arthritis between June 2022 and December 2024. Patients were stratified according to spacer type: preformed cement spacer or Hofmann spacer. Functional recovery was assessed using Knee Society Score (KSS), Oxford Knee Score (OKS), and Forgotten Joint Score (FJS) during the interstage period and after reimplantation. Residual pain was evaluated using the Visual Analogue Scale (VAS). Range of motion (ROM), septic and aseptic failure and complications were analyzed. Results Fifteen patients were included: seven treated with a Hofmann spacer and eight with preformed cement spacers. During the interstage period, one patient in the cement spacer group experienced spacer dislocation. Patients treated with Hofmann spacers showed significantly better interstage functional outcomes. Mean KSS and OKS were 95.43 ± 6.5 vs 40.12 ± 13.3 and 44.4 ± 0.9 vs 21.9 ± 5.7, respectively (p = 0.001). FJS values were also significantly higher (79.34 ± 5.9 vs 32.9 ± 5.1; p = 0.001), indicating lower joint awareness. Pain and mobility were improved in the Hofmann group, with VAS scores 0.71 ± 0.76 vs 3.75 ± 1.83 and mean ROM 1.43°–122.1° vs 6.2°–68.7°. After reimplantation, outcomes remained superior in the Hofmann group. Mean postoperative KSS was 97.4 ± 3.6 vs 77 ± 6.2 (p = 0.001), OKS 46.4 ± 1.1 vs 37.7 ± 5.6 (p = 0.003), and FJS 91.4 ± 6.5 vs 75.6 ± 8.03 (p = 0.003). Postoperative pain levels were comparable (VAS 0.6 ± 0.9 vs 1.5 ± 0.9; p = 0.06), while ROM remained greater in the Hofmann group (1°–129° vs 4.38°–104.4°). Conclusion Both approaches achieved high infection eradication. However, the Hofmann articulating spacer provided significantly superior functional recovery, ROM, and patient-reported outcomes both during the interstage period and after reimplantation, supporting its use in selected patients with native septic knee arthritis.