The impact of adjuvant antibiotic hydrogel application on the primary stability of uncemented hip stems.

Objectives: To assess the effect of adjuvant antibiotic-loaded hydrogel application on the primary stability of implanted uncemented hip stems. Design: Biomechanical study. Setting: An electro-mechanic material test system (#5866, Instron, Norwood, MA, USA) equipped with a 10-kN load cell was used. A staircase loading protocol was applied via quasi-static ramped compression loading at 0.005 mm/s and six different load levels between 500 N and 3000 N in 500 N intermittent load increase steps. Participants: 12 artificial femora were prepared and received a collarless uncemented standard offset stem (Corail; DePuy Synthes, Zuchwil, Switzerland). Interventions: The two groups were prepared with or without the antibiotic-loaded hydrogel. Main outcome measures: Construct stiffness was determined from the recorded load-displacement curves and stem subsidence was measured via motion tracking. Results: Construct stiffness (control: 4176±240 N/mm; intervention: 4588±448 N/mm) was not significantly different between the groups (p=0.076). Stem subsidence increased significantly over the increasing load levels in each separate group (p≤0.002) and remained not significantly different between the groups (p=0.609). Conclusions: The application of antibiotic-loaded hydrogel was associated with non-inferior performance in terms of primary uncemented hip stem stability. This finding makes the prospect of adjuvant antibiotic-loaded hydrogel application potentially feasible; however, it requires further investigations prior to translation in the clinical practice.