SLR- March 2014- Jacob Stuart
Reference: Ambrose CG, Clyburn TA, Mika J, Gogola GR, KaplanHB, Wanger A, Mikos AG; The Journal of Bone & Joint Surgery. 2014 Jan; 96(2):128-134.
Reviewed by: Jacob Stuart, DPM
Residency Program: Botsford Hospital
Podiatric Relevance: The post-operative course of an infected implant can be long and challenging. With the possible side effects and comorbities associated with an infected implant, including prolonged high dose antibiotics and possible joint destructive procedures, prevention of an infection may be the best method to avoid these complications. The purpose of this study was to determine whether bioresorbable antibiotic microspheres could be used with porous metal implants to prevent infection in a contaminated wound.
Methods: Bioresorbable polymer microspheres containing tobramycin were manually implanted into porous metal cylinders and implanted into aradial bone defect of rabbits. The animals in the study had an antibiotic impregnated metal cylinder implanted into one limb and a control metal cylinder implanted in the contralateral limb. Both sites were then directly contaminated with Staphylococcus aureus and the incision sites closed. The animals were then euthanized when the first signs of infection appeared, or at two weeks. The tissue surrounding the prosthetic was then cultured and the implant evaluated for in growth of bone.
Results: A total of eleven rabbits completed the study. Of the eleven, there were no positive cultures on the limbs containing the antibiotic impregnated metal cylinders. In the control limb, culture results were positive in seven rabbits (64%). Four animals tested negative for cultures in bilateral limbs. As far as the tissue in growth of the implant, there was significantly decreased in growth noted to the implants of the infected limbs. However, there was no statistical significance between the treated and untreated limbs that were not infected.
Conclusion: The results indicate that antibiotic microspheres can be used effectively with porous metal implants to prevent infection in all the animals studied. It was also noted that the microspheres did not hinder tissue ingrowth into the implant. One advantage to this system is that these microspheres can be added to already manufactured and presterilized porous implants by simple applications. Also, previous studies have shown that the microspheres deliver antibiotics over a period of weeks rather than hours. With the well known complications associated with infected implants, this study introduces a method that can potentially decrease the rate of infection in the post-op patient. Couple that with the fact the microspheres did not decrease the incorporation of bone into the implant, this technique should be considered as an adjunct when using metal implants.