Clinical Feasibility and Mechanical Reliability of a Modified Functional Articulating Hip Spacer Incorporating a...

Background: Periprosthetic joint infection and native hip infections often require staged surgical intervention due to extensive bone and soft tissue destruction. This study evaluates the clinical feasibility and mechanical reliability of a modified functional articulating hip spacer (FAHS) incorporating a cemented dual-mobility-bearing (DMB) metal liner. Methods: We retrospectively reviewed the cases of 20 patients who underwent a DMB-incorporated FAHS between March 2018 and December 2019. The technique involved cementing a DMB metal liner directly into the prepared acetabulum without a standard outer shell. Successful clinical outcome was defined as either transition to second-stage total hip arthroplasty (THA) or stable spacer retention, the latter including cases with definitive eradication or symptom-controlled chronic suppression therapy. Infection eradication required the clinical absence of infection for at least twelve months following the cessation of antimicrobial therapy. Construct-related mechanical complications and radiographic parameters were also analyzed. Results: The mean follow-up was 23.5 months, ranging from 6.0 to 62.6 months. Successful clinical outcome was achieved in 17 patients (85%), with seven (35%) transitioning to second-stage THA and ten (50%) opting for spacer retention. Within the retention group, seven achieved definitive eradication while three were maintained under chronic suppression therapy. Construct integrity was maintained in 80% of the cohort. Mechanical complications included two dislocations (10%) and two implant failures (10%). Radiographic analysis showed higher inclination and anteversion angles of the metal liner in the dislocation cases. Conclusions: The off-label use of DMB-incorporated FAHS represents a feasible option with acceptable mechanical performance in selected cases of PJI and native hip joint infection. However, as mechanical complications cannot be fully prevented, meticulous surgical techniques and careful patient selection remain essential.