Supercritical Solution Impregnation: A Strategy to Prevent Prosthetic Infections

One of the most devastating and frustrating complications in orthopaedic surgery is infection. A project is underway in our laboratory to explore the use of supercritical CO₂ (scCO₂) as an impregnation medium for treating orthopaedic prostheses to prevent infections. We present our results on the incorporation of antibiotics into the polymeric part of prostheses (inserts) using scCO₂ as a green solvent capable of penetrating the inserts carrying the drug without altering their structural integrity. Experiments were performed using pieces of actual knee joint liners of cross-linked ultra-high molecular weight polyethylene (UHMWPE) cut into small pieces. Materials were impregnated with the antibiotic clindamycin dissolved in CO₂ at 35-55°C and 100-200 bar. Moderate loadings (0.13%-1.85% mass) were obtained due to the compact nature of the UHMWPE liners and the weak interaction between the drug and the support. Drug loading increased with the CO₂ density and the depressurization rate. The impregnated prosthesis pieces were free of solvent residues and exhibited antibacterial activity against S. epidermidis, evidenced by the formation of inhibition halos, confirming the effectiveness of this approach in preventing bacterial colonization.