A 65-year-old female ECF patient had a history of obesity and noninsulin-requiring diabetes mellitus, operated in 2007 for left total hip arthroplasty (THA) and in 2009 for right THA (both surgeries were performed in another center).
Her first visit to Clinical Hospital of Universidad de Chile, in December 2013, was for a 2-year history characterized by pain and functional impotence in the right hip, associated with recurrent febrile episodes and fistula in relation to scarring of the THA. In another center, it was managed with surgical lavage, debridement, and prolonged antibiotic treatments. General examinations, dated December 2013, include erythrocyte sedimentation rate (ESR, 54) and C-reactive protein (CRP, 30 mg/L).
Chronic periprosthetic infection was diagnosed (Tables 1 and 2). It was decided to suspend antibiotics (atb), and arthrocentesis under radiography was programmed after 3 weeks of the atb suspension. Positive polymicrobial culture was obtained from arthrocentesis for Proteus mirabilis and multisensitive Staphylococcus aureus.
It was decided to perform an arthroplasty revision in two stages. First stage was scheduled for March 2014. Fistula resection, complete prosthesis removal, surgical lavage and debridement, tissue cultures, femoral intramedullary reaming, and vancomycin cement spacer were performed.  Figure 1 shows the postoperative radiograph. The cultures of intraoperative tissues obtained were positive for Staphylococcus aureus (3/5) and Proteus mirabilis (2/5), confirming the bacteriological diagnosis of arthrocentesis. After surgery, antibiotic treatment with intravenous vancomycin was restarted for 2 weeks, switching to oral ciprofloxacin for 40 days.
It evolves favorably, without pain, without signs of systemic infection in the surgery wound.  Figure 2 shows the evolution of ESR and CRP, which were in decline, even after the atb suspension.
Given the favorable evolution, it was decided to carry out the second stage. On July 2, 2014, spacer removal, taking of new cultures, and uncemented total hip arthroplasty were performed. Postoperative radiography is shown in Figure 3. After second stage, patient evolved favorably, managing to walk with 2 canes, declining HSV and CRP, and negative intraoperative cultures. It was discharged without antibiotic treatment.
She consulted one week after medical discharge, due to a one-day evolution episode, characterized by 39.5 C fever, right coxalgia, and secretion in relation to the surgery wound. Examinations are taken, in which leukocytosis 16,550, ESR 32, and CRP 22 are noticed. Hospitalization was decided at the same day of admission, and arthrocentesis under radiography was performed obtaining 145 cc of serohematic fluid that was sent for cultures. Hemocultures were negative at 5 days, and arthrocentesis cultures were positive to multisensitive negative coagulase Staphylococcus. Due to the time of evolution (Table 1) and the isolation of a microorganism different from the chronic infection, an acute periprosthetic infection was diagnosed. So, it was decided to perform a one-stage revision.
On July 25, 2014, surgical lavage and debridement and prosthesis removal were done, 7 culture samples are taken, and total uncemented arthroplasty was performed. Postoperative radiography is shown in Figure 4. Five of seven intraoperative cultures were positive for multisensitive negative coagulase Staphylococcus, which is consistent with arthrocentesis. After three weeks of endovenous antibiotic treatment, in conjunction with infectology, it was decided to prescribe amoxicillin 875 mg + clavulanic acid 125 mg every 12 hr for 3 months at hospital discharge.
It evolved favorably, with no new signs of systemic or local infection: movement without walking sticks and decrease of ESR and CRP, which was maintained after the suspension of the antibiotic (Figure 5).
   HSS: 77.9 points (fair)
   HOOS: 88.8%
   WOMAC: 93.8%
The follow-up was until March 2017, that is, 32 months after the last surgery. Radiographs were taken (Figure 6), and functional scores were applied. The Harris Hip Score (HSS) was developed to evaluate the results of hip surgery, the Hip Disability and Osteoarthritis Outcome Score (HOOS) aimed to evaluate the patient's opinion about his hip and associated problems, and to this joint with or without osteoarthritis, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) assessed the functionality and quality of life of patient with hip and knee pathology. The results obtained from the patient are as follows: