**5. Treatment**

### **5.1 Treatment goal**

Optimal treatment of prosthetic joint infections involves the eradication of infection whilst maintaining function of the joint and patient quality of life (Zimmerli, et al. 2004). However there are no large, multi-centred, randomised prospective studies of treatment strategies to guide recommendations. The successful treatment of prosthetic joints is contingent on the elimination of the biofilm dwelling microorganism. The two mainstay methods of achieving this are through either surgical removal of the prosthesis or through use of biofilm active antibiotics in conjunction with surgical debridement and retention of the prosthesis.

The surgical strategies used to treat arthroplasty infections include: resection arthroplasty, one-stage or two-stage exchange procedures, amputation and debridement and retention. Resection arthroplasty entails the removal of all foreign material including cement, resection of devitalised tissue and bone and may or may not involve arthrodesis. Exchange procedures involve resection arthroplasty with reimplantation of a new joint prosthesis performed at the time of removal of the infected prosthesis (one-stage exchange); or delayed by a variable period of time while antibiotic therapy is administered (two-stage exchange). Debridement and retention of the prosthesis usually involves open arthrotomy, removal of all infected and necrotic bone, exchange of liners and lavage of the joint (Giulieri, et al. 2004, Matthews, et al. 2009, Rand, et al. 1986, Steckelberg & Osmon 2000, Trampuz & Zimmerli 2008, Zimmerli, et al. 2004).

A number of factors influence the surgical approach selected for an individual patient, these include a patient's general health and fitness for anaesthesia, condition of the prosthesis and bone stock, the causative agent, the timing of the infection relative to the prosthesis insertion, the availability of effective antibiotics and clinicians' and patient preference.

### **5.2 Systemic antibiotic therapy without surgical debridement**

Administration of antibiotic therapy without surgical management is not routinely recommended, as it is rarely associated with successful cure. Early studies of antibiotic therapy alone for prosthetic joint infections had disappointing results with successful outcomes in as little as 8-15% of patients (Bengtson, et al. 1989, Canner, et al. 1984). The confounding factor when analysing these poor results is that biofilm active antibiotics, were not used. Treatment with biofilm active antibiotics alone including rifampicin and ciprofloxacin for three to six months has yielded successful outcomes in highly selected patients; those presenting with early infections (less than one year following implant), infection due to *Staphylococcus aureus*, absence of implant loosening and strict adherence to treatment (Trebse, et al. 2005). However, antibiotic suppression alone is generally reserved for patients with significant comorbidities in whom surgery is contraindicated, who are without evidence of systemic infection and where tolerable oral antibiotics are available. Given the low likelihood of cure, many clinicians view this as long term, often lifelong suppressive therapy, embarked upon without curative intent (Steckelberg & Osmon 2000, Zimmerli, et al. 2004).
