Antibacterial efficacy of a new gentamicin‐coating for cementless prostheses compared to gentamicin‐loaded bone cement

Cementless prostheses are increasingly popular but require alternative prophylactic measures than the use of antibiotic‐loaded bone cements. Here, we determine the 24‐h growth inhibition of gentamicin‐releasing coatings from grit‐blasted and porous‐coated titanium alloys, and compare their antibacterial efficacies and gentamicin release‐profiles to those of a commercially available gentamicin‐loaded bone cement. Antibacterial efficacy increased with increasing doses of gentamicin in the coating and loading with 1.0 and 0.1 mg gentamicin/cm² on both grit‐blasted and porous‐coated samples yielded comparable efficacy to gentamicin‐loaded bone cement. The coating had a higher burst release than bone cement, and also inhibited growth of gentamicin‐resistant strains. Antibacterial efficacy of the gentamicin coatings disappeared after 4 days, while gentamicin‐loaded bone cement exhibited efficacy over at least 7 days. Shut‐down after 4 days of gentamicin‐release from coatings is advantageous over the low‐dosage tail‐release from bone cements, as it minimizing risk of inducing antibiotic‐resistant strains. Both gentamicin‐loaded cement discs and gentamicin‐coated titanium coupons were able to kill gentamicin‐sensitive and ‐resistant bacteria in a simulated prothesis‐related interfacial gap. In conclusion, the gentamicin coating provided similar antibacterial properties to those seen by gentamicin‐loaded bone cement, implying protection of a prosthesis from being colonized by peri‐operatively introduced bacteria in cementless total joint arthroplasty. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1654–1661, 2011