Aim

To analyse the prevalence of culture negative periprosthetic joint infections (PJI) when adequate culture techniques are applied, and to evaluate the outcome of patients who were treated with antibiotics for a culture negative PJI versus those in whom treatment was withheld.

Aim

We aimed to assess the incidence and the outcome of Gram-negative prosthetic-joint infections (PJI) in 3 international tertiary hospital.

Aim

There is a constant increase of total joint arthroplasties to improve the quality of life of an aging population. Prosthetic-joint infections are rare, with an incidence of 1–2%, but they represent serious complications in terms of morbidity and mortality. Different therapeutic options exist, but the role of the surgeon's experience has never been investigated. The aim of this retrospective study is to assess the infection eradication success rate depending on the involvement of a septic surgeon.

Aim

There is a constant increase of total joint arthroplasties to improve the quality of life of an aging population. Prosthetic-joint infections are rare, with an incidence of 1–2%, but they represent serious complications in terms of morbidity and mortality. Different therapeutic options exist, but their management is still poorly standardized because of the lack of data from randomized trials. The aim of this retrospective study is to assess the infection eradication success rate, over the last ten years, using different patient adapted treatment options.

Aim

There is a constant increase of joint arthroplasties to improve the quality of life of an aging population. Prosthetic-joint infections are rare, with an incidence of 1–2%, but they represent serious complications in terms of morbidity and mortality. The mortality was known to be approaching 8% in the elderly. The aim of this retrospective study is to reassess the two-year mortality rate over the last ten years.

Aim

When treating periprosthetic joint infections with a two-stage procedure, antibiotic-impregnated spacers are used in the interval between removal of prosthesis and reimplantation. The spacer provides local antibiotics; however, it may also act as foreign-body that can be colonized by microorganisms. According to our experience, cultures of sonicated spacers are most often negative.

The objective of our study was to investigate whether PCR analysis would improve the detection of bacteria in the spacer sonication fluid.

Different therapeutic options for prosthetic joint infections exist, but surgery remains the key. With a two-stage exchange procedure, a success rate above 90% can be expected. Currently, there is no consensus regarding the optimal duration between explantation and the reimplantation in a two-stage procedure. The aim of this study was to retrospectively compare treatment outcomes between short-interval and long-interval two-stage exchanges.

Patients having a two-stage exchange of a hip or knee prosthetic joint infection at Lausanne University Hospital (Switzerland) between 1999 and 2013 were included. The satisfaction of the patient, the function of the articulation and the eradication of infection, were compared between patients having a short (2 to 4 weeks) versus a long (4 weeks and more) interval during a two-stage procedure. Patient satisfaction was defined as good if the patient did not have pain and bad if the patient had pain. Functional outcome was defined good if the patient had a prosthesis in place and could walk, medium if the prosthesis was in place but the patient could not walk, and bad if the prosthesis was no longer in place. Infection outcome was considered good if there had been no re-infection and bad if there had been a re-infection of the prosthesis

145 patients (100 hips, 45 knees) were identified with a median age of 68 years (range 19–103). The median hospital stay was 58 days (range 10–402). The median follow-up was 12.9 months (range 0.5–152). 28 % and 72 % of the patients had a short-interval and long-interval exchange of the prosthesis, respectively. Patient satisfaction, functional outcome and infection outcome for patients having a short versus a long interval are reported in the Table.

The patient satisfaction was higher when a long interval was performed whereas the functional and infection outcomes were higher when a short interval was performed. According to this study a short-interval exchange appears preferable to a long interval, especially in the view of treatment effectiveness and functional outcome.

The costs related to the treatment of infected total joint arthroplasties represent an ever groving burden to the society. Different patient-adapted therapeutic options like débridement and retention, 1- or 2-step exchange can be used. If a 2-step exchange is used we have to consider short (2–4 weeks) or long (>4–6 weeks) interval treatment. The Swiss DRG (Diagnose related Groups) determines the reimboursement the hopsital receives for the treatment of an infected total arthroplasty.

The review assesses the cost-effectiveness of hospitalisation practices linked to surgical treatment in the two-stage exchange of a prosthetic-joint infection. The aim of this retrospectiv study is to compare the economical impact between a short (2 to 4 weeks) versus a long (6 weeks and above) interval during a two-satge procedure to determine the financial impact.

Retrospectiv study of the patients with a two-stage procedure for a hip or knee prosthetic joint infection at CHUV hospital Lausanne (Switzerland) between 2012 and 2013. The review analyses the correlation between the interval length and the length of the hospital stay as well as with the costs and revenues per hospital stay.

In average there is a loss of 40′000 Euro per hospitalisation for the treatment of prosthetic joint infection. Revenues never cover all the costs, even with a short interval procedure. This economical loss increases with the length of the hospital stay if a long-term intervall is choosen.

The review explores potential for improvement in reimbourement practices and hospitalisation practices in the current Swiss healthcare setting. There should be alternative setups to decrease the burden of medical costs by a) increase the reimboursment for the treatment of infected total joints or by b) splitting the hospital stay with partners (rapid transfer after first operation from center hospital to level 2 hospital and retransfer for second operation to center) in order to increase revenues.

Objectives

Establishing the diagnosis of implant-associated infections is often difficult, because of variable clinical presentations and lack of uniform diagnostic criteria. Sonication of removed orthopedic devices was shown to have superior sensitivity and specificity for infection. We evaluated the value of microcalorimetry as a quick and reliable tool in the diagnosis of infection in sonication fluid from removed implants.

Objectives

The risk of infection after type III° open fractures is high (10–50%). Preemptive antibiotic therapy may prevent posttraumatic infection and improve the outcome. Recommendations about the type and duration of antibiotic vary among the institutions and it remains unclear whether gram-negative bacilli or anaerobs need to be covered.

In Europe, the most commonly recommended antibiotic is amoxicillin/clavulanic acid.

We retrospectively analyzed microbiology, characteristics and outcome of patients with open type III° fractures treated at our institution.

Objectives: Total ankle replacement (TAR) is increasingly used for treatment of primary or posttraumatic arthritis of the ankle joint, if joint movement is intended to be preserved. Data on characteristics and treatment of ankle prosthetic joint infection (PJI) is limited and no validated therapeutic algorithm exist. Therefore, we analyzed all infections, which occurred in a cohort of implanted ankle prostheses during a 5-year-period.

Methods: Between 06/2004 and 12/2008, all patients with an implanted ankle prosthesis at our institution were retrospectively reviewed. All patients were operated by the same surgical team. Ankle PJI was defined as visible purulence, acute inflammation on histopathology, sinus tract, or microbial growth in periprosthetic tissue or sonication fluid of the removed prosthesis. The surgery on the infected ankle prosthesis and the follow-up were performed by the surgical team, who implanted the prosthesis. A specialized septic team consisting of an orthopaedic surgeon and infectious diseases consultant were included in the treatment.

Results: During the study period, 92 total ankle prostheses were implanted in 90 patients (mean age 61 years, range 28–80 years). 78 patients had posttraumatic arthritis, 11 rheumatoid arthritis and 3 other degenerative disorder. Ankle PJI occurred in 3 of 92 TAR (3.3%), occurring 1, 2 and 24 months after implantation; the causative organisms were Enterobacter cloacae, Streptococcus pyogenes and Staphylococcus epidermidis, respectively. The ankle prosthesis was removed in all infected patients, including debridement of the surrounding tissue was debrided and insertion of an antibiotic loaded spacer. Provisional arthrodesis was performed by external fixation in two patients and by plaster cast in one. A definitive ankle arthrodesis with a retrograde nail was performed 6 to 8 weeks after prosthesis removal. One patient needed a flap coverage. All 3 patients received intravenous antibiotic treatment for 2 weeks, followed by oral antibiotics for 4–6 weeks. At follow-up visit up to 18 months after start of treatment, all patients were without clinical or laboratory signs of infection.

Conclusions: The infection incidence after TAR was 3.3%, which is slightly higher than reported after hip (< 1%) or knee arthroplasty (< 2%). A two-step approach consisting of removal of the infected prosthesis, combined with local and systemic antibiotic treatment, followed by definitive ankle arthrodesis shows good results. Larger patient cohort and longer follow-up evaluation is needed to define the optimal treatment approach for ankle PJI.

Background: Bacteria form a biofilm on the surface of orthopaedic devices, causing persistent and infection. Little is known about biofilms formation on bone grafts and bone substitutes. We analyzed various representative materials regarding their propensity for biofilm formation caused by Staphylococcus aureus.

Methods: As bone graft beta-tricalciumphosphate (b-TCP, CyclOsTM) and as bone substitute a tantalum metal mesh (trabecular metalTM) and PMMA (Pala-cosTM) were investigated. As test organism S. aureus (strain ATCC 29213) was used. Test materials were incubated with bacterial solution of 105 colony-forming units (cfu)/ml at 37°C for 24 h without shaking. After 24 h, the test materials were removed and washed 3 times in normal saline, followed by sonication in 50 ml Ringer solution at 40 kHz for 5 minutes. The resulting sonication fluid was plated in aliquots of 0.1 ml onto aerobe blood agar with 5% sheep blood and incubated at 37°C with 5% CO2 for 24 h. Then, bacterial counts were enumerated and expressed as cfu/ml. All experiments were performed in triplicate to calculate the mean ± standard deviation. The Wilcoxon test was used for statistical calculations.

Results: The three investigated materials show a differing specific surface with b-TCB> trabecular metal> PMMA per mm2. S. aureus formed biofilm on all test materials as confirmed by quantitative culture after washing and sonication. The bacterial counts in sonication fluid (in cfu/ml) were higher in b-TCP (5.1 x 106 ± 0.6 x 106) and trabecular metal (3.7 x 106 ± 0.6 x 106) than in PMMA (3.9 x 104 ± 1.8 x 104), p< 0.05.

Conclusion: Our results demonstrate that about 100-times more bacteria adhere on b-TCP and trabecular metal than on PMMA, reflecting the larger surface of b-TCP and trabecuar metal compared to the one of PMMA. This in-vitro data indicates that bone grafts are susceptible to infection. Further studies are needed to evaluate efficient approaches to prevent and treat infections associated with bone grafts and substitutes, including modification of the surface or antibacterial coating.

Background: Antibiotic-loaded spacers and cement nails are commonly used in patients undergoing a two-stage implant exchange procedure for treatment of prosthetic joint infection (PJI). During re-implantation 2–6 weeks after implant removal, tissue specimens are collected to document successful eradication of infection. However, these specimens have limited sensitivity, especially in patients receiving antimicrobial treatment. We investigated the value of sonication of removed spacers and cement nails.

Methods: We prospectively included patients in whom a spacer or cement nail was removed from January 2007 through April 2009 during a two-stage exchange procedure. The removed temporary device was sonicated in a container with Ringer’s solution in an ultrasound bath for 5 min at 40 kHz (as described in NEJM2007;357:654). The resulting sonication fluid was cultured aerobically and anaerobically for 10 days. In parallel, > 2 tissue samples were collected for conventional cultures on blood agar plates and enrichment broth. PJI was defined as visible purulence, acute inflammation on histopathology, sinus tract or significant microbial growth in tissue or implant sonication cultures.

Results: In this ongoing study, 28 spacers and 10 cement nails from patients with confirmed PJI were included (median age 75 y; range 49–86 y). All devices were impregnated with antibiotics (gentamicin and/or vancomycin) and were placed in the hip (n=21), knee (n=9) or shoulder joint region (n=7). At the time of explantation, the following pathogens were isolated: coagulase-negative staphylococci (n=19), Staphylococcus aureus (n=7), Streptococcus agalactiae (n=3), Propionibacterium acnes (n=5) and mixed infection (n=4). All patients received systemic antibiotics for a median of 19 days (range 11–42 days) before removal of the spacer/nail. At the time of re-implantation, tissue cultures were negative in all 38 patients, whereas sonication cultures showed growth of Propionibacterium acnes in 2 of 38 patients (5%) with a hip and shoulder spacer, both in significant numbers (150 and 550 colonies/ml sonication fluid, respectively). These organisms were probably present as mixed infection already at the time of explantation, but were missed due to overgrowth due to another organism (S. aureus in one patient and coagulase-negative staphylococci in another). Both patients were not initially treated for the Propionibacterium acnes infection, but the treatment was given after re-implantation.

Conclusion: Sonication of removed spacers is a suitable approach to identify persistent infection in patients with a two-stage exchange. Sonication may replace the current standard approach consisting of multiple tissue specimens in order to document successful eradication of infection.

Background: Negative pressure wound treatment is increasingly used through a Vacuum-Assisted Closure (VAC) device in complex wound situations. For this purpose, sterile polyurethane (PU) and polyvinyl alcohol (PVA) foam dressings are fitted to the wound size and covered with an adhesive drape to create an airtight seal. Little information exists about the type and quantity of microorganisms within the foams. Therefore, we investigated VAC foams after removal from the wound using a validated method (sonication) to detect the bacterial bioburden in the foam consisting as microbial biofilms.

Methods: We prospectively included VAC foams (PU and PVA, KCI, Rümlamg, Switzerland) without antibacterial additions (e.g. silver), which were removed from wounds in patients with chronic ulcers from January 2007 through December 2008. Excluded were patients with acute wound infection, necrotizing fasciitis, underlying osteomyelitis or implant. Removed foams from regular changes of dressing were aseptically placed in a container with 100 ml sterile Ringer’s solution. Within 4 hours after removal, foams were sonicated for 5 min at 40 kHz (as described in NEJM2007;357:654). The resulting sonication fluid was cultured at 37°C on aerobic blood agar plates for 5 days. Microbes were quantified as No. of colony-forming units (CFU)/ml sonication fluid and identified to the species level.

Results: A total of 68 foams (38 PU and 30 PVA) from 55 patients were included in the study (median age 71 years; range 33–88 years, 57% were man). Foams were removed from the following anatomic sites: sacrum (n=29), ischium (n=18), heel (n=13), calves (n=6) and ankle (n=2). The median duration of being in place was 3 days (range, 1–8 days). In all 68 foams, bacteria were found in large quantities (median 105 CFU/ml, range 102–7 CFU/ml sonication fluid. No differences were found between PU and PVA foams. One type of organisms was found in 11 (16%), two in 17 (24%) and 3 or more in 40 (60%) foams. Gram-negative rods (Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa) were isolated in 70%, followed by Staphylococcus aureus (20%), koagulase-negative staphylococci, streptococci (8%), and enterococci (2%).

Conclusion: With sonication, a high density of bacteria present in VAC foams was demonstrated after a median of 3 days. Future studies are needed to investigate whether antimicrobial-impregnated foams can reduce the bacterial load in foams and potentially improve wound healing.

Background: Bacteria form biofilms on the surface of orthopaedic devices, causing persistent infections. Monitoring biofilm formation on bone grafts and bone substitutes is challenging due to heterogeneous surface characteristics. We analyzed various bone grafts and bone substitutes regarding their propensity for in-vitro biofilm formation caused by S. aureus and S. epidermidis.

Methods: Beta-tricalciumphosphate (β-TCP, Chro-nOsTM), processed human spongiosa (TutoplastTM) and PMMA (EndobonTM) were investigated. PE was added as a growth control. As test strains S. aureus (ATCC 29213) and S. epidermidis RP62A (ATCC 35984) were used. Test materials were incubated with defined bacterial solution (105 colony-forming units (cfu)/ml) at 37°C for 24 h without shaking. After 24 h, the test materials were removed and washed 3 times in PBS, followed by a standardised sonication protocol (Trampuz et al. 2007, NEJM). The resulting sonication fluid was plated in aliquots of 100μl onto aerobe blood agar with 5% sheep blood and incubated at 37°C with 5% CO2 for 24 h. Bacterial counts were enumerated and expressed as cfu/ml. Sonicated samples were transferred to a microcalorimeter (TA Instrument) and heat flow at 37°C was continuously monitored over a 24h period with a precision of 0.0001°C and a sensitiviy of 200μW. All experiments were performed in triplicates to calculate the mean ± standard deviation. ANOVA analysis was used for statistical calculations.

Results: For S. aureus bacterial counts (log10 cfu/ sample) were significantly higher (p< 0.001) for the porous (β-TCP 7.67 ± 0.17, Tutoplast 7.65 ± 0.15) than for the solid samples (PMMA 6.12 ± 0.18, PE 5.17 ± 0.22). Bacterial density (log10 cfu/surface) was 10^1–10^2 times higher for the S. epidermidis than for the S. aureus. In calorimetry the shape of the heat flow curves was characteristic for the individual strain and was not influenced by the test materials. The time to detection (TTD) was shortest for β-TCP for both strains and TTD was always shorter for S. aureus than S. epidermidis with corresponding material. Cfu/sample calculated from the calorimetric data was concordant with the standard culturing method.

Conclusion: Our results demonstrate biofilm formation with both strains on all tested materials. The calorimetry in all cases was able to detect quantitatively the amount of biofilm. Further studies are needed to see whether calorimetry is a suitable tool also to monitor approaches to prevent and treat infections associated with bone grafts and bone substitutes.

Introduction: Despite a multitude of reports detailing the management of infected hips and knees with or without arthroplasty, only little information is available on how to deal with infected shoulders. Besides primary haematogenous infection, the increasing number of surgical procedures (infiltration, arthroscopy, ORIF, total- or hemi arthroplasty) confront the orthopaedic surgeon increasingly with this devastating complication. Our goal is to present our experience with the use of a cement spacer in the treatment of infected shoulder joints.

Material and Methods: Between 1995 and 2005 9 patients were diagnosed with deep shoulder infection. The study includes 5 women and 4 men. The mean age at the time of diagnosis of the infection was 65 years (range, 51–78 years). Only 2 patient had had no prior surgery of the shoulder. 5 patients had an infection of a shoulder arthroplasty and 2 patients had been treated with ORIF for fracture.

All of the patients underwent resection the humeral head or retrieval of the arthroplasty with large debridement followed by implantation of an antibiotic impregnated polymethyl methacrylate spacer. After a mean duration of two months of antibiotics and after normalisation of the CRP a delayed reimplantation of a prosthesis was performed in 6 patients. One patient is awaiting arthroplasty, while two patients are satisfied with the functional result obtained with the spacer and do not want further surgery.

Results: None of the patients developed recurrent infection at an average follow-up time of 36 months. Shoulder function was judged objectively and subjectively to be at least satisfactory in all of the patients.

Conclusions: Staged treatment of infected shoulders using antibiotic impregnated polymethyl methacrylate spacers showed in our small group of patients, good and reproducible results. The individually moulded and fitted spacer filling the joint cavity and restoring the normal anatomy of the shoulder after joint debridement makes secondary procedures much easier. In the cases of exchange prosthetic reconstruction no recurrent infection has been experienced and all of the patients have substantial pain relief and an adequate shoulder function. Based on this experience the authors think that staged treatment and the use of a cement spacer in infected shoulder joints is a valid approach.

Aims: 1) to create a new and reproducible animal model to produce heterotopic ossification (HO) 2) to be able to exactly quantify the amount of HO using a microCT scan and 3) to prove the hypothesis that COX-2 inhibitors are efficacious in the prevention of HO. Methods: We developed a IACUC-approved Lewis rat model, in which the ventral side of the right femur was scraped to mechanically disrupt the periosteum. By clamping the vastus intermedius ischemic injury to the muscle was produced to enhance HO. Finally homologous bone marrow from a donor rat was placed on the anterior surface of the femur. Half of the study group (8 rats) received chow mixed with a COX-2 inhibitor, while the other half received normal chow. After 6 weeks the animals were sacrificed, the femurs removed and imaged by microCT. Grading of HO was based on the thickness of ectopic bone as evaluated in a blinded fashion by 3 independent observers. Results: All animals developed bilateral HO. Rats treated with COX-2 inhibitors developed significantly less ectopic bone than the control group rats. Conclusions: The results suggest that we have created a very reliable, reproducible model to form ectopic bone in rats. Using the microCT we can precisely quantify the amount of HO. We have been able to show that COX-2 inhibitors significantly decrease the amount of HO formation and are thus a good alternative to non-specific NSAIDs with their potential serious side effects on the gastrointestinal tract and on hemo-stastis.

Aims: To determine the results of Òbiologic þxationÒ with a minimally invasive plating technique using a newly designed low proþle ÒScallopÒ plate in the treatment of pilon fractures. Methods: 17 patients were treated between 1999 and 2001 for a tibial plafond with a newly designed ultra-slim plate. Eleven (65%) were high-energy injuries, two were open. Staged open reduction and þxation of the þbular fracture and application of an External Fixator was performed in 12 cases. As soon as the soft tissues and swelling allowed, the articular surface was reconstructed and anatomically reduced, if necessary through an small incision, and the articular block was þxed to the diaphysis using a medially placed, percutaneously introduced ßat Scallop plate. Time to healing and complications were evaluated. Quality of the results and outcome were graded using the Ankle-Hindfoot-Scale. Results: All patients went on to bony union at an average time of 14.1 weeks. There were no plate failures or loss of þxation/ reduction. Two superþcial wound-healing problems resolved with local wound care. At an average FU of 17 months eight patients (47%) had an excellent, seven (41%) a fair and two (12%) a poor result. The average AHS was 86.1. Conclusions: Based on these initial results, it appears that a minimally invasive surgical technique using a new low proþle plate can decrease soft tissue problems while leading to fracture healing and obtaining results comparable with other more recent series. We believe that this new ÒScallop PlateÒ is appropriate for the treatment of pilon fractures and should be used in conjunction with a staged procedure in the acute trauma setting.

Aims: Nonunions of the distal tibia are difþcult to treat due to the short distal segment, the proximity to the ankle joint and the fragile soft tissue envelope. Intramedullary nailing is an attractive solution as it avoids extensive soft tissue dissection and remains intraosseus, posing little problem for the soft tissues. The purpose of this study was to determine the efþcacy of reamed intramedullary nailing in the treatment of non-unions of the distal one-quarter of the tibia. Methods: Thirty-two patients with nonunions of the distal one-quarter of the tibia were treated by reamed, locked intramedullary nailing. Prior treatments included casting as well as intramedullary or extramedullary þxation techniques. No patient had signs of an active infection at the time of surgery. Time to union, correction of deformity and complications including infection and reoperation were examined. Results: Twenty-nine out of thirty-two patients achieved union at an average of 3.5 months after surgery. Of the remaining three, two patients united rapidly after dynamisation and one after exchange nailing. Deformity was corrected to a maximum of four degrees in all planes. Four patients had positive intraoperative culture, and only two required removal of the nail after achieving union to eradicate infection. There were no cases of chronic osteomyelitis after the procedure. Conclusions: Reamed, locked intramedullary nailing is a reliable and safe procedure in the treatment of nonunions in the distal one-quarter of the tibia. It allows for excellent correction of deformity, which is an essential component of the procedure.