Impact of surface structuring on antibiotic elution from bone cement in two-stage revision for periprosthetic joint infection

Abstract Purpose Periprosthetic joint infection (PJI) is a serious complication after total joint arthroplasty and the leading cause of revision surgery. Two-stage revision with prosthesis removal, radical debridement, and interim antibiotic-loaded bone cement (ALBC) spacers is the current gold standard. ALBC spacers provide high local antibiotic concentrations and maintain joint space, with articulating designs improving interim mobility. Antibiotic release depends on cement composition, antibiotic content, and surface area, but the impact of surface structure remains unclear. This study investigated how surface morphology and area affect gentamicin and vancomycin release from ALBC in vitro. Methods Copal G + V cement (2 g vancomycin, 0.5 g gentamicin per 43 g) was cast into standardized rectangular blocks according to DIN ISO 5833. A reference group without surface structuring and three groups with progressively increasing surface area and depth were analyzed. After polymerization, specimens were incubated in phosphate-buffered saline at 37 °C. Antibiotic release was measured at defined intervals over six weeks using chemiluminescence immunoassay (CLIA). Results Surface structuring resulted in a clear increase in cumulative antibiotic release, particularly for vancomycin, with a consistent relationship between surface enlargement and total elution. The greatest surface structuring led to the highest release levels. Gentamicin showed a similar but less pronounced response, with a notable increase only at the highest degree of surface enlargement. The initial burst release contributed substantially to overall elution, while later-phase release differences between groups were less marked. Conclusion Surface modification of PMMA cement influenced antibiotic elution in this in vitro experimental model, with increased surface depth resulting in enhanced vancomycin release. Gentamicin elution was less affected by surface geometry and showed significant improvement only with the greatest surface enlargement. These findings indicate that structured cement surfaces may influence local antibiotic release characteristics under controlled laboratory conditions. However, the clinical relevance of these surface modifications remains to be determined, as this study was limited to cement blocks incubated in phosphate-buffered saline and did not include a spacer, infection, or in vivo model. Further experimental and in vivo investigations are required to assess whether surface structuring can improve antibiotic delivery in clinically relevant settings.