Sterilizing Effects of the Erbium:YAG Laser Upon Metal Implants

Background:

Even today, postoperative infection is the commonest complications after surgery although all aseptic precautions are taken and causes significant postoperative morbidity, mortality, prolongs hospital stay, and increases costs. Infections that are related to orthopaedic procedures are considered particularly severe when implantation materials are used which further increases the risk of infection and holds the risk of biofilm formation. This is of particular concern since biofilm-mediated infections are difficult to diagnose and effective treatments are lacking. Therefore, new strategies for implant infection are currently being researched worldwide. In this study the relatively new approach for infection control by using an Er:YAG laser was adapted to an orthopaedic and traumatologic setting. This laser vaporizes all water containing cells in a very effective, precise and predictable manner and shows only a minimal thermal damage.

Methods:

For preliminary testing 42 steel pins and 42 plates were cultivated with cocultures for 2 weeks. The minimally necessary laser energy for biofilm removal was determined. We subsequently compared the effectiveness of biofilm removal with the Er:YAG laser and a cleansing of the metal implants with Octenidine soaked gauze. The temperature rise within the metal during the laser procedure was also measured.

In order to achieve an approximation to a clinical setting we want to compared the same effectiveness of biofilm removal similarly on steel pins directly after explantation from patients treated with external fixators for at least 2 weeks. Sonication and SEM will be used for analysis.

Preliminary Results Laser fluences exceeding 2.8J/cm2 caused a complete extinction of all living cells by a single laser impulse. Temperature rise within the implant is dependent on repetition frequency but overall negligible.

The effectiveness of biofilm removal after cleansing with Octenidine soaked gauze and irradiation with the Er:YAG laser will be evaluated on cultivated and extracted pins.

Conclusions We want to compare the effectiveness of the Er:YAG laser and Octenidine in the removal of biofilms from half-pins. We hypothesize that thee Er:YAG laser offers a secure, complete and non toxic removal of all kinds of pathogens from steel implants without damaging the implant or possible development of resistances. The precise non-contact removal of adjacent tissue could be an advantage over other disinfectants.

Level of Evidence (II-a)

Clinical Relevance:

Having one more arrow in the quiver for disinfection of percutaneous implants or for septic revision surgery when osteosynthesis equipment or arthroplasties are meant to be left in place would be extremely desirable.