Abstract
INTRODUCTION
Surgical site infections (SSI) in orthopaedics are a major source of postoperative morbidity. Although perioperative antibiotic prophylaxis is a common practice, orthopaedic infections are still high in numbers, due to the increasing use of osteosynthesis material and implants. Implants are avascular and can be easily colonized with biofilm-producing germs. For both, effective prophylaxis and treatment of orthopaedic infections, the right choice of the antibiotics used, the mode of application (only systemic or systemic & local), the timing, dosage and the duration of antibiotics are of extremely high importance. Their inappropriate use does not only lead to failures in prevention or treatment of infections, but may also promote microbial resistance development and may cause serious side effects for the patients.
SELECTION & USE OF ANTIBIOTICS
Prophylaxis
Broad-spectrum prophylactic antibiotics should help to eliminate the germs before they start to colonize the implant. For prophylactic purposes the recently published AAOS guidelines [1] recommend the use of cephalosporins, such as cefazolin or cefuroxim, administered within one hour prior to surgery. In cases of suspected beta-lactam allergy, clindamycin or vancomycin can be used. The latter one is also recommended in cases of MRSA colonisation. Due to extended infusion times, vancomycin should be started within two hours prior to incision. In cases of blood loss or long op duration, antibiotic administration must be repeated (e.g. cefazolin, every 2–5 hrs; vancomycin, every 6–12 hrs). There is no evidence of a benefit of continued antibiotic administration past 24 hrs of end of surgery [2]
Treatment
In cases of established infections, use of antibiotics is only considered as an adjuvant to surgical debridement. Typically, the choice of the appropriate antibiotic depends on the bacteria, its antibiotic sensitivity profile and the health state of the patient. A combination of rifampicin & a quinolone (or rifampicin & vancomycin in cases of MRSA) for at least 2 wks up to several months has shown good results [3]. In chronic infections with biofilm involvement, all foreign material must be removed and locally delivered antibiotics via e.g. PMMA as carrier (spacers, PMMA-chains) are of additional clinical benefit.
ROLE OF LOCAL ANTIBIOTICS
There is general consensus that PMMA chains or PMMA spacers loaded with specific antibiotics support the eradication of bone and joint infections, because of the high local concentrations achieved. The exact treatment time is, however, variable, ranging from few weeks up to several months. Only small amounts of these local antibiotics are systemically detectable and do not represent a major risk for side effects. Still a matter of debate is the benefit of antibiotic impregnated PMMA for infection prophylaxis. Although common practice in Europe, its routine use in e.g. primary arthroplasty is still discussed in other world regions. Meanwhile, evidence accumulates that joint infection rates are, indeed, lower, if antibiotic loaded bone cement with high initial release rates is routinely used in arthroplasty4.
