Introduction

Periprosthetic joint infections (PJI) represent a significant clinical challenge, especially with increasing implant volumes, often necessitating multiple revision surgeries. Only few anti-infective implant coatings are currently clinically available with the aim to prevent biofilm formation, and systemic antibiotic treatments alone inadequately inhibit biofilm growth.

We developed a biocompatible poly-L-lactic acid (PLLA)-based coating containing homogeneously dissolved silver ions for sustained anti-infective efficacy. Additionally, the coating allows non-invasive extracorporeal shock wave (ESW)-triggered silver ion burst-release directly at the implant site.

Methods

Coating efficacy was evaluated in both preventive and therapeutic modes. Preventive biofilm inhibition was assessed using Staphylococcus epidermidis RP62A. ESW-triggered therapeutic silver release was quantified via graphite furnace atomic absorption spectrometry (GF-AAS). Morphological changes post-activation were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and confocal laser scanning microscopy (CLSM). Growth curves assessed antibacterial activity following ESW activation. A combined assay with established biofilm followed by ESW activation measured bacterial reduction after 24 hours.

Results

A 6% silver-containing PLLA coating significantly reduced biofilm formation 1000-fold compared to uncoated titanium controls. ESW activation released 57.8 ± 0.05 mg/L silver ions. SEM, EDX, and CLSM confirmed localized coating disruption correlating with silver release. Growth curves showed a 12-hour delay in bacterial proliferation post-activation. The combined biofilm and ESW assay achieved complete bacterial eradication within 24 hours.

Conclusions

The PLLA-based implant coating effectively prevents and treats PJI by enabling controlled, targeted silver ion release via non-invasive ESW activation, complementing systemic antibiotic therapies.