Growing up the patient became a farmer in a Swiss mountain area. Up to the age of 46 years, he frequently suffered from a sinus tract infection with intermittent painful pus retentions. At first presentation to our clinic, a central sequestra in the distal femur was found and eliminated by a lateral fenestration of the distal femur. This procedure was combined with central medullary reaming of the whole femur [2, 3]. No communication with the knee joint was noted at this time. In the biopsies S. aureus was identified and subsequently treated with 2 weeks of intravenous flucloxacilline (4 × 2 g) followed by 6 months of oral ciprofloxacine (2 × 750 mg) and rifampicin (2 × 450 mg) [4]. The follow-up was uneventful with no signs of recurrence for the following 10 years (Fig. 1).

Then the patient experienced progressive weight-bearing right knee pain. Due to his limitations in daily activity, he presented to a local orthopaedic surgeon. The orthopaedic surgeon recommended a TKR.

However, as the orthopaedic surgeon feared a recurrence of the previous infection, he primarily performed a diagnostic arthroscopy and took three biopsies. These showed no bacterial growth.

A CT and an anti-granulocyte bone scan did not reveal any signs of infection. There was extensive scar tissue in the anterior knee compartment. Finally a non-hinged TKR was performed using a lateral approach including an osteotomy of the tibial tubercle (Fig. 2).

Approximately 2 weeks later, the patient presented with a persistent pus secretion and wound dehiscence over the patellar tendon, which was right in the centre of the pre-existing anterior scar area.

After a second (arthroscopic) revision, vacuum treatment was initiated. The treatment was continued for a total of 4 months, but the sinus persisted. The antibiotic treatment was continued with oral levofloxacin (2 × 500 mg) and rifampicin (2 × 450 mg). Neither healed the sinus (Fig. 3) nor did the C-reactive protein (CRP) decrease below 15 mg/l.

At this stage the patient was again referred to our clinic. The knee was swollen, warm, and red.

The radiographs did not show any osseous integration of the tubercle fragment (Fig. 2). An anti-granulocyte bone scan revealed increased tracer activity around the prosthesis, which indicated a periprosthetic joint infection. The open fistula penetrated the patellar ligament partially destroying it (Fig. 3).

The following plan for treatment was proposed to the patient:

Removal of the TKR, bridging of the knee with external fixation, curative intravenous antibiotic treatment for 6 weeks; 1 week after removal of the TKR, replacement of the scar area by a free flap; reimplantation 8 weeks after removal of the TKR and an antibiotic-free interval of 2 weeks (Fig. 4) [5].

Eleven tissue samples – equal portions for microbiologic and histologic examination – were harvested. The implants were sent for sonication [6]. Antibiotic treatment was started empirically, first with amoxicillin and clavulanic acid but then had to be changed to vancomycin (2 × 1 g) and levofloxacin (2 × 500 mg). Eight days later, the plastic surgeon performed a free lateral upper arm flap including an anastomosis of a skin nerve. Part of the aponeurosis of the M. triceps brachii was taken with the graft and integrated in the deficient patellar tendon.

The microbiologic analysis of the samples revealed a complex situation of six different bacteria, all three strains of staphylococci being resistant against rifampicin. Doxycycline was then added to the antibiotic therapy. After final microbiological results, the antibiotic treatment was changed to vancomycin 2 × 1 g i.v. and oral doxycycline (Table 1).