Purpose

Fracture-related infection (FRI) is an important complication related to orthopaedic trauma. Although the scientific interest with respect to the diagnosis and treatment of FRI is increasing, data on the microbiological epidemiology remains limited. Therefore, the primary aim of this study was to evaluate the microbiological epidemiology related to FRI, including the association with clinical symptoms and antimicrobial susceptibility data. The secondary aim was to analyze whether there was a relationship between the time to onset of infection and the microbiological etiology of FRI.

To report mid-term results of PJI treated with uncemented stems.

: 80 hips of PJI after THA were treated with uncemented stems from 01/1993 to 12/2012 and followed prospectively. Selection occurred for one- (n=27) or two-stage (n=53) exchange according to the Liestal algorithm. Surgical approaches were transfemoral (n=58), transgluteal (n=9) or transtrochanteric (n=13). A monoblock (Wagner SL, n=58) or modular (Revitan, n=22) revision stem was implanted. On the acetabular side 44 Müller rings, 33 Burch-Schneider cages (combined with a cemented PE-cup) and 3 press-fit cups were used. Kaplan-Meier survival was calculated for endpoints (a) persistence of infection, (b) septic/aseptic stem loosening. Radiographs were analysed for (a) subsidence, (b) distal stem integration, (c) changes in cortical thickness, (d) proximal femur restoration, (e) radiolucency around stem/cup.

Mean FU was 5.2 (2–15) years. PJI was eradicated in 77 of 80 hips (96%). 3 patients (all two-stage) had a treatment failure. 2 were treated successfully with an additional two-stage exchange. In the 3rd patient we were not able to control infection and exarticulation was performed. Furthermore, one stem was revised for aseptic loosening (5 years), 1 for a broken Wagner stem (7 years) and 1 for subsidence (8 months). Stem survival after 5 years was 93% (SD ±2.5 years). 2 cups were revised for aseptic loosening and 1 for recurrent dislocations. Subsidence ≥5mm was found in 6 hips and occurred always within 3 months after surgery independent of stem type (p=0.947) and approach (p=0.691). Proximal femoral remodelling after transfemoral approach was excellent or good in 71% (32 excellent, 9 good) with no difference between one-/two-stage exchanges (p=0.288). Initial distal stem integration was 65mm medial and 66mm lateral and increased to 8mm medial (p=0.716) and 10mm lateral (p<0.001). Cortical thickness was unchanged over the entire FU period (p=0.493). Radiolucencies were seen around 26 stems, only the stem revised after 5years was rated loose.

Eradication of PJI was high using our established protocol even with uncemented revision stems. Mid-term survival was independent from one-/two-stage revision and comparable to results for aseptic loosening revision.

Debridement, antibiotics and implant retention (DAIR) is an established treatment option for periprosthetic joint infection (PJI). Success rates of more than 90% cure have been reported with proper patient selection. While a meticulous debridement of the joint and an appropriate postoperative antibiotic therapy is important for treatment success, the relevance of changing mobile parts is still a matter of debate. The latter procedure is only possible with an extensive soft tissue release, potentially destabilizing the joint. Though, it is impossible with polyethylene-inlays being no longer available. The aim of this study was to evaluate whether cure of PJI with DAIR is influenced by retaining the mobile parts.

Between 01/2004 and 12/2012, 36 patients with 39 episodes of THA-associated infections were treated with DAIR according to our algorithm (NEJM 2004). All patients met the IDSA criteria for DAIR with a stable implant and either a PJI diagnosed during the first postoperative month or a haematogenous PJI with infectious symptoms of less than three weeks. Patients were treated either with a complete debridement, including an exchange of all mobile parts (n=24), or with a complete debridement and retaining mobile parts (n=15). Postoperatively all patients received standardized antibiotic treatment (NEJM 2004).

The patients’ mean age at the time of infection was 74 (SD 9) years. Average time between onset of symptoms and DAIR were 3.6 (0–28) days; Five patients died before the 2-year-follow-up unrelated to PJI. Mean follow-up of the remaining patients was 45.6 (24–119) months. 20 PJI were early postoperative, 15 haematogenously acquired, and four unclear. The most frequent causative microorganisms were coagulase-negative staphylococci (n=16), S. aureus (n=8), streptococci (n=5) and E. coli (n=2). Ten episodes were polymicrobial, and nine cases culture-negative. The overall success rate of all 39 episodes treated with DAIR was 95% (37/39). Two treatment failures were observed, both after haematogenous S. aureus infection and exchange of mobile parts. One of them refused further surgery and was treated with a suppressive antibiotic therapy. The other one had a one-stage exchange four months after DAIR showing a loose cup intraoperatively.

Patients treated with DAIR strictly according to our treatment algorithm show a favourable result regarding overall success rate. From our data it seems debatable, whether the exchange of all mobile parts is mandatory, or should be individually evaluated in each case.

Summary

Staphylococcus aureus isolates from Fracture fixation device related infections contained fewer isolates that form a strong biofilm in comparison with isolates from Prosthetic joint infections. Both orthopaedic implant related infection groups possessed fnbB and sdrE more frequently than the non-implant related infection groups.

At our institution, periprosthetic hip joint infections are treated according to a previously defined treatment algorithm. Each patient is evaluated regarding risk factors such as duration of clinical signs and symptoms, stability of the implant, condition of the soft tissue, and antimicrobial susceptibility of the microorganism. Depending on these factors, either debridement with retention, one-stage exchange, or two-stage exchange with spacer (short interval, 2–4 weeks), or without spacer (long interval, 8 weeks) is performed. Very rarely, resection arthroplasty or lifetime suppression is necessary. All surgical procedures are combined with an antimicrobial therapy for 6 or 12 weeks, depending on the surgical pathway. For infection due to staphylococci, whenever possible, rifampicin is used in combination with a fluoroquinolone. From 2002–2006, 89 patients with 95 episodes (3 patients with 2 independent episodes, 3 patients with bilateral infection) of periprosthetic hip joint infection have been treated at our hospital. Five patients died within 2 years after revision, one of them with septic shock related to the periprosthetic hip joint infection. One patient is living abroad. All other patients (n=83) had consecutive follow-up visits at least until 2 years after infection treatment without recurrence. Debridement with retention has been performed in 18 episodes, one-stage exchange in 25 episodes, two-stage exchange with temporary spacer for 2–4 weeks has been performed in 26 episodes, and two-stage exchange without spacer and an interval of 8 weeks in 19 episodes. In 4 cases, immediate resection arthroplasty was performed and 3 patients received long-term suppression therapy. After debridement with retention, 3 recurrences and one event of death occurred (4/18=22.2%), 3 of them did not fulfil the criteria of the algorithm. No failure was observed after one-stage exchange (0/25). Treatment with two-stage exchange was followed by one failure in the group with spacer and short interval (1/26=3.8%), as well as one in the group without spacer and long interval (1/19=5.3%). No recurrence occurred after resection arthroplasty or suppression therapy. All 5 patients with relapse could be cured with a one- or two-stage exchange and remained without recurrence. Comparing one-stage versus two-stage exchange, one-stage exchange is known to have better functional results. It is associated with better patient acceptance, shorter hospital stay, and therefore lower economic burden.

In conclusion, one-stage exchange implies no increasing risk of recurrence provided that the standards of our algorithm are considered.

Implant-associated infections do not spontaneously cure. The reason for persistence in device-associated infections is the biofilm, a specialized form of bacterial growth on surfaces. The biofilm represents a survival form of bacteria which is highly resistant against most antibiotics, and can persist over months or years as low-grade infection. Bacteria in biofilms enter a metabolically inactive state, embedded in an amorphous substance, called biofilm matrix. Together they form a complex three-dimensional structure with rudimentary communication and circulation systems.

As a rule, only a combined surgical and antimicrobial management can eradicate biofilms and cure implant-associated infection. In selected patients, implant infections can be cured without implant removal with early debridement and long-term antibiotic treatment acting against biofilms. In this presentation, common pitfalls and reasons for treatment failure will be outlined and discussed.

Adequate diagnosis. Every prosthesis with early loosening (< 2 years after implantation) or persistent/increasing pain should rise the suspicion of an implant-associated infection, which may presents without systemic signs of infection (fever), and can manifest without increased leukocyte counts or C-reactive protein). In this case, periimplant infection must be actively searched. Preoperative diagnosis includes aspiration of the synovial fluid of larger joints for Gram stain and culture; cell count and differential; and crystals (if appropriate). Swabs of the sinus tract (fistula) should not be performed, since they may not represent the causing organisms of the bone- or implant-associated infection. Intraoperative diagnosis includes multiple tissue biopsies around the prosthesis (no swabs), histopathology of the periprosthetic tissue and sonication of the removed device or its parts (if the method is available). For low-virulent organisms (such as Staphylococcus epidermidis or Propionibacterium acnes) at least two positive specimens with the same organism or an additional criterion for infection (i.e. acute inflammation in the tissue histopathology, presence of intraoperative pus or fistula) is needed. For slow-growing organisms, long incubation is needed (14 days) in order to culture these slow-growing and fastidious pathogens. Antibiotics should be discontinued at least 2 weeks prior to culture sample in order to minimize false-negative results. Novel diagnostic tests include PCR, which can also detect non-growing microorganisms and can be used for tissue specimens, joint aspirate or sonication fluid.

In conclusion, using the proposed diagnostic and treatment algorithm (Zimmerli et al. NEJM2004; 351: 1645), the long-term success rate of periprosthetic joint infection is 80–90%. To avoid failure, it is important to select the patient for the least invasive, but still appropriate surgical and antibiotic treatment regimen and to avoid mistakes.

Introduction: In treatment for prosthetic hip joint infection (PHJI), the advantages of a 1-stage exchange over the classic 2-stage approach are the lower morbidity and earlier rehabilitation. Secondly, a recently published treatment algorithm for PHJI using well-defined selection criteria for 1-stage exchange had a 85–100% rate of cure for infection. Patient satisfaction after hip surgery is highly influenced by the functional result. We hypothesized that in our used algorithm the functional and radiological outcomes after a 1-stage exchange due to an implant-associated infection would be similar to a matched control group of 1-stage exchange due to aseptic loosening.

Material and Methods: Twenty-two cases (21 patients), with PHJI according to a well-defined definition, after 1-stage exchange of the prosthesis strictly according to the algorithm, with index-surgery between april 1996 and october 2004, were included in the studygroup. Case-matching was performed with aseptic revised cases for previous surgery, type of implant, use of transfemoral osteotomy, Charnley score, duration of follow-up, age, and sex. Outcome measures were perioperatively complications, functional results (Harris hip score, limping, and use of walking support) at two years, and the occurrence of revision for any reason and radiological loosening at latest follow-up. All outcomes were compared between both groups and with the results of the two stage revisions in our cohort. Finally, the eradication of infection was scored.

Results: In 86% of the 1-stage group (n = 19) there was an event-free follow-up for ≥ 2 years. The mean Harris hip score was 84, the incidence of limping 20% and 10% required two crutches. Two stems were revised due to aseptic loosening. Both functional and radiological outcomes were not different from the matched control group.

In the 2-stage group (n = 50) results were lower but not significantly, with 80, 30% and 28% respectively, and 2 stems and 1 cup were revised due to aseptic loosening.

One case (after one stage) developed an infection with a different pathogen and one case (after two stage exchange) had a relaps of infection.

Conclusion: By using the identical surgical technique in both septic and aseptic revision hip surgery, functional results are comparable between groups. These results indicate that 1-stage exchange according to a strict algorithm leads to a successful outcome in both maintaining functional mobility and eradicating infection.

Implants are highly susceptible to infection [1]. The infection rate is 0.5–2% after hip or knee arthroplasty [2]. Periprosthetic joint infections are hard to eradicate. Until recently, two-stage exchange or life-long antibiotic suppression therapy has been the rule. However, novel treatment concepts evolved. Whereas no controlled trials on the surgical management of prosthetic-joint associated infection are available, much is known about the optimal antimicrobial therapy. Modern treatment concepts are based on animal studies, in vitro data, observational studies and one single controlled trial comparing two different antimicrobial regimens in patients with orthopaedic device-associated infections [2]. The tissue-cage guinea pig model is especially suitable to analyse the role of antibiotics in device-related infections [3]. In this model, different aspects of implant-associated infections have been studied, namely

host-defense mechanisms around implants [1],

Taken together, these experiments showed that an agent acting on slow-growing and adhering microorganism is needed to eradicate device-associated infection. This requirement is only fulfilled by rifamycins in staphylococcal infection and by fluoroquinolones in infections caused by gram-negative bacilli [5–12]. We could show that even new drugs against methicillin-resistant staphylococci (MRSA), such as linezolid and daptomycin, were not able to eradicate experimental foreign-body infections, when used as single agents. In contrast, in combination with rifampin linezolid cured 60%, and daptomycin 67% of the implant-associated MRSA-infections [9,10]. Based on these in vitro and animal data, observational studies were performed in patients with staphylococcal infections associated to orthopedic devices. We developed an algorithm allowing to choose the optimal therapeutic option for each patient [2]. This algorithm has been validated in cohort studies [13,14]. Finally, in a randomized double-blind controlled trial, the benefit of a rifampin-quinolone combination as compared to quinolone monotherapy has been proven in patients with acute orthopedic implant associated staphylococcal infection undergoing debridement with retention [15].

In conclusion, the favorable role of rifampin has been proven in vitro, in animals and in human studies. Also the newest antistaphylococcal agents must be given in combination with rifampin in order to eliminate infection without removal of the device.