The incidence of periprosthetic knee infection is generally low (0.5%–2%) but the economic impact is great. The rates are higher for rheumatoid arthritis and revision knee surgery. Treatment of periprosthetic knee infection takes into account the acuteness of the infection, the overall immune/medical status of the patient, and the local factors at the site of infection.

Evaluate the results of two-phase exchange arthroplasty with the use of articulating spacer in III-A-1 and III-B-1 periprosthetic knee infection.

From 1990–2005, 24 patients with minimum (< 2) systemic and no local compromising factors were treated for chronic periprosthetic knee infection. These patients staged as III-A-1 or III-B-1 according to MSIS staging system. Diagnosis was clinical, radiological, laboratory and from knee aspiration cultures. Two-phase exchange arthroplasty was performed. Initially, there was removal of the prosthesis, surgical debridement and placement of a PMMA spacer impregnated with antibiotic. The spacer was shaped as a knee joint permitting motion. In 6 cases a hybrid spacer was used (PMMA and TECRES® spacer). Intravenous antibiotic therapy according to intraoperative cultures followed for 6–8 weeks. Re-implantation was always done after the completion of the antibiotic therapy and on the ground of normal CRP, ESR and negative aspiration cultures. All patients received antibiotics after the re-implantation.

Staphylococcus aureus was the most common pathogen followed by Staphylococcus epidermidis and Pseudomonas aeruginosa. No infection recurrence was noted over a 2–15 years follow-up. All patients returned to normal everyday activity. A custom-made prosthesis was placed in one patient and there was a rupture of the extensor mechanism in another.

Patients with periprosthetic knee infection, staged as III-A-1 and III-B-1, when treated with two-stage exchange arthroplasty combined with antibiotic impregnated articulating spacer and i.v. antibiotics can have excellent results.