Introduction. The use of irrigation solution during surgical procedures is a common and effective practice in reduction of bioburden and the risk of subsequent infection. The optimal irrigation solution to accomplish this feat remains unknown. Many surgeons commonly add topical antibiotics to irrigation solutions assuming this has topical effect and eliminates bacteria. The latter reasoning has never been proven. In fact a few prior studies suggest addition of antibiotics to irrigation solution confers no added benefit. Furthermore, this practice adds to cost, has the potential for anaphylactic reactions, and may also contribute to the emergence of antimicrobial resistance. We therefore sought to compare the antimicrobial efficacy and cytotoxicity of irrigation solution containing polymyxin-bacitracin versus other commonly used irrigation solutions. Methods. Using two in vitro breakpoint assays of Staphylococcus aureus (ATCC#25923) and Escherichia coli (ATCC#25922), we examined the efficacy of a panel of irrigation solutions containing topical antibiotics (500,000U/L Polymyxin-Bacitracin 50,000U/L; Vancomycin 1g/L; Gentamicin 80mg/L), as well as commonly used irrigation solutions (Normal saline 0.9%; Povidone-iodine 0.3%; Chlorhexidine 0.05%; Castile soap 0.45%; and Sodium hypochlorite 0.125%) following 1 minute and 3 minutes of exposure. Surviving bacteria were counted in triplicate experiments. Failure to eradicate all bacteria was considered to be “not effective” for that respective solution and exposure time. Cytotoxicity analysis in human fibroblast, osteoblast, and chrondrocyte cells exposed to each of the respective irrigation solutions was performed by visualization of cell structure, lactate dehydrogenase (LDH) activity and evaluation of vital cells. Toxicity was quantified by determination of LDH release (ELISA % absorbance; with higher percentage considered a surrogate for cytotoxicity). Descriptive statistics were used to present means and standard deviation of triplicate experimental runs. Results. Polymyxin-Bacitracin, Saline and Castile soap irrigation at both exposure times were not effective at eradicating S aureus or E coli (Figure 1). In contrast, Povidone-iodine, Chlorhexidine, and Sodium hypochlorite irrigation were effective at eradicating both S aureus and E coli. Vancomycin irrigation was effective at S aureus eradication but not against E coli, whereas Gentamicin irrigation showed partial efficacy against E coli eradication but none against S aureus. The greatest cytotoxicity was seen with Chlorhexidine (49.4% ± 1.9). This was followed by Castile soap (33.2% ±3.9), Vancomycin (9.01% ±5.1), Polymyxin-Bacitracin (8.45% ±1.5), and Gentamicin irrigation (4.72% ±2.3) (Figure 2 and Figure 3 microscopy images). Povidone-iodine and Sodium hypochlorite showed least cytotoxicity (0.05% ±0.08 and 0.11%±0.19, respectively). Similar trends were seen at both exposure times and across fibroblasts, osteoblasts and chondrocytes. Discussion. This in vitro study suggests that addition of polymyxin-bacitracin to saline irrigation solution is a futile exercise. Taken within the context of its associated expense, risk of hypersensitivity and impact upon antimicrobial resistance, our findings bring its widespread clinical usage into question. Povidone-iodine may be a more effective option, with a more favorable cytotoxicity profile than the other commonly used irrigation solutions. Clinical outcomes should be studied to determine the most effective agent, concentration, and exposure time for intraoperative irrigation

Aim. The efficacy of various irrigation solutions in removing microbial contamination of a surgical wound and reducing the rate of subsequent surgical site infection (SSI), has been demonstrated extensively. However, it is not known if irrigation solutions have any activity against established biofilm. This issue is pertinent as successful management of patients with periprosthetic joint infection (PJI) includes the ability to remove biofilm established on the surface of implants and necrotic tissues. The purpose of this study was to evaluate the efficacy of various irrigation solutions in eradicating established biofilm, as opposed to planktonic bacteria, in a validated in vitro model. Method. Established biofilms of Staphylococcus aureus and Escherichia coli were exposed to different irrigation solutions that included Polymyxin 500,000U/L plus bacitracin 50,000U/L, Vancomycin 1g/L, Gentamicin 80mg/L, Normal saline 0.9%, off-the-shelf Betadine 0.3%, Chlorhexidine 0.05%, Benzalkonium 1.3g/L, Sodium hypochlorite 0.125%, and Povidone-iodine 0.5%. Each experiment was conducted in a 96-well microtiter plate with a peg lid and standardized per the MBEC assay manufacturer's protocol. Following 2 minutes of solution exposure to the irrigation solution, residual biofilms were recovered by sonication. Outcome measures for antibiofilm efficacy were residual colony forming units (CFU) and optical density (690nm). Experiments were conducted in 24 replicates and the observations recorded by two blinded observers. Statistical analysis involved t-tests with Bonferonni adjustment. Results. Povidone-iodine 0.5%, Betadine 0.3%, Benzalkonium 1.3g/L, and Sodium hypochlorite 0.125% were significantly more efficacious against S.aureus biofilm versus all other solutions (p<0.001). Against E.coli biofilm, Povidone-iodine-0.5%, Benzalkonium-1.3g/L and Sodium hypochlorite-0.125% were also most effective compared to other irrigation solutions (p<0.001). Polymyxin-bacitracin, Gentamicin, Vancomycin, and Saline solutions had minimal activity against both E.coli and S.aureus biofilms (p<0.001). Similar trends were observed using both experimental endpoints (CFU and Turbidity) and both investigators (interrater reliability; r=0.99). Conclusion. This in vitro study observed that topical antibiotic solutions do not have any activity against established biofilms. Irrigations solutions containing adequate amount of povidone-iodine, betadine, sodium hypochlorite, and benzalkonium appear to have activity against established biofilm by gram positive and gram negative organisms. The use of these irrigation solutions may need to be considered in patients with established PJI

The two-staged exchange for periprosthetic joint infection (PJI) has become the “gold standard” worldwide. Based on the first implementation of mixing antibiotics into bone cement by Prof. Buchholz in the 1970s, the ENDO-Klinik followed a distinct one staged exchange for PJI in over 85 % of all our infected cases until today. Looking carefully at current literature and guidelines for the PJI treatment, there is no clear evidence, that a two-staged procedure has a clearly higher success rate than a one-staged approach. Although postulated in relevant articles, most recommendations, e.g. duration of antibiotics, static vs. mobile spacer, interval of spacer retention, cemented vs. uncemented implant fixation, are based on Level IV to III evidence studies or expert opinions, rather than on prospective randomised or comparative data. Potentially a cemented one-stage exchange offers certain advantages, as mainly based on need for only one operative procedure, reduced antibiotics & hospitalization time and reduced relative overall costs. In order to fulfill a one-staged approach with the above described potential success, there are obligatory pre-, peri- and postoperative details, which need to be meticulously respected. The absolute mandatory infrastructural requirement is based on the clear evidence of the bacteria in combination with a distinct patient specific plan, by an experienced microbiologist, for following topical antibiotics in the bone cement with combined systemic antibiotics. Mandatory preoperative diagnostic testing is based on the joint aspiration with an exact identification of the bacteria. The presence of a positive bacterial culture and respective antibiogramm is essential, to specify the antibiotics loaded into the bone cement, which allows a high topical antibiotic elution directly at the surgical site. A specific treatment plan is generated by a microbiologist. Contraindications for a one-staged exchange include: failure of >2 previous one-staged procedures, infection spreading to the nerve-vessel bundle, unclear preoperative bacteria specification, unavailability of appropriate antibiotics, high antibiotic resistance. The surgical success relies not only on the complete removal of all preexisting hardware material (including cement and restrictors), furthermore an aggressive and complete debridement of any infected soft tissues and bone material is needed. Mixing antibiotics into the cement needs to fulfill the following criteria: Appropriate antibiogramm, adequate elution characteristics, bactericidal (exception clindamycin), powder form (never use liquid AB), maximum addition of 10 %/PMMA powder. Current principles of modern cementing techniques should be applied. Postoperative systemic antibiotic administration is usually followed for only 10–14 days (exception: streptococci). We recommend an early and aggressive mobilization within the first 8 days postoperatively, due to the cemented fixation an immediate mobilization under full weight bearing becomes possible in most cases. Persistence or recurrence of infection remains the most relevant complication in the one-staged technique. As failure rates with a two-staged exchange have been described between 9% and 20% in non-resistant bacteria, the ENDO-Klinik data shows comparative results after 8–10 years of follow up. In summary a cemented one-stage exchange offers various advantages. Mainly the need for only one operation, shorter hospitalization, reduced systemic antibiotics, lower overall cost and relative high patient satisfaction. However, a well-defined preoperative planning regime including an experienced microbiologist is absolutely mandatory

The two-staged exchange for periprosthetic joint infection (PJI) has become the “gold standard” worldwide. Based on the first implementation of mixing antibiotics into bone cement by Prof. Buchholz in the 70's, the ENDO-Klinik followed a distinct one-staged exchange for PJI in over 85% of all our infected cases until today. Looking carefully at current literature and guidelines for the PJI treatment, there is no clear evidence, that a two-staged procedure has a clearly higher success rate than a one-staged approach. Although postulated in relevant articles, most recommendations, e.g. duration of antibiotics, static vs. mobile spacer, interval of spacer retention, cemented vs. uncemented implant fixation, are based on level IV to III evidence studies or expert opinions, rather than on prospective randomised or comparative data. Potentially a cemented one-stage exchange offers certain advantages, as mainly based on need for only one operative procedure, reduced antibiotics & hospitalization time and reduced relative overall costs. In order to fulfill a one-staged approach with the above described potential success, there are obligatory pre-, peri- and post-operative details, which need to be meticulously respected. The absolute mandatory infrastructural requirement is based on the clear evidence of the bacteria in combination with a distinct patient specific plan, by an experienced microbiologist, for the topical antibiotics in the bone cement with combined systemic antibiotics. Mandatory pre-operative diagnostic testing is based on the joint aspiration with an exact identification of the bacteria. The presence of a positive bacterial culture and respective antibiogramm is essential, to specify the antibiotics loaded to the bone cement, which allows a high topical antibiotic elution directly at the surgical site. A specific treatment plan is generated by a microbiologist. Contraindications for a one-staged exchange include: failure of > 2 previous one-staged procedures, infection spreading to the nerve-vessel bundle, unclear pre-operative bacteria specification, unavailability of appropriate antibiotics, high antibiotic resistance. The surgical success relies not only on the complete removal of all preexisting hardware material (including cement and restrictors), furthermore an aggressive and complete debridement of any infected soft tissues and bone material is needed. Mixing antibiotics to the cement needs to fulfill the following criteria: Appropriate antibiogramm, adequate elusion characteristics, bactericidal (exception clindamycin), powder form (never use liquid AB), maximum addition of 10%/PMMA powder. Current principles of modern cementing techniques should be applied. Post-operative systemic antibiotic administration is usually followed for only 10–14 days (exception: streptococci). We recommend an early and aggressive mobilization within the first 8 days post-operatively due to the cemented fixation an immediate mobilization under full weight bearing becomes possible in most cases. Persistence or recurrence of infection remains the most relevant complication in the one-staged technique. As failures rates with a two-staged exchange have been described between 9% and 20% in non-resistant bacteria, the ENDO-Klinik data shows comparative results after 8–10 years of follow up, which were confirmed independently also by some other international reports and study groups. In summary a cemented one-stage exchange offers various advantages. Mainly the need for only one operation, shorter hospitalization, reduced systemic antibiotics, lower overall cost and relatively high patient satisfaction. However a well-defined pre-operative planning regime including an experienced microbiologist is absolutely mandatory

Topically applied vancomycin powder has been used to decrease surgical site infection rates in spinal surgeries, however, randomized controlled trials in total joint arthroplasty are lacking. Application of vancomycin powder topically in the surgical site has theoretical benefit including high local concentration. In this study, we aimed to determine whether intra-operative topical antibiotics are safe and effective as IV antibiotics in preventing post-surgical site infections. The trial was a randomized controlled, double blind, non-inferiority study. All patients received pre-operative IV antibiotics (cefazolin or vancomycin) within 60 minutes of skin incision. The controlled group received two doses of post-operative IV antibiotics (two grams cefazolin or one gram vancomycin if cefazolin allergy). In the treatment group, the orthopaedic surgeon applied one gram vancomycin powder (500mg applied directly on the prosthesis and 500mg applied above the closed joint capsule). The incidence of acute surgical site infection was defined as positive deep cultures within 42 days of procedure. All patients with evidence of infection underwent joint aspiration for culture. After one year, 80 patients had received the topical vancomycin treatment and 85 patients had received the standard treatment. In the topical vancomycin group versus the controlled group, the average age was 64 vs 66, average BMI was 35.7 vs 33.4, number of males 33 vs 29, number of females 47 vs 56, and diabetic patients 16 vs 13. The number of infections in the topical vancomycin group was three vs zero in the post-operative IV antibiotic treatment group. One Tailed Z-test P Value = 0.03. This study statistically demonstrated inferiority of topical vancomycin in comparison to the use of IV antibiotics post-operatively in preventing deep wound infections in TKA. The authors would caution against the sole use of intra-operative vancomycin in TKA to prevent post-operative infection

Aims

Bacterial infection activates neutrophils to release neutrophil extracellular traps (NETs) in bacterial biofilms of periprosthetic joint infections (PJIs). The aim of this study was to evaluate the increase in NET activation and release (NETosis) and haemostasis markers in the plasma of patients with PJI, to evaluate whether such plasma induces the activation of neutrophils, to ascertain whether increased NETosis is also mediated by reduced DNaseI activity, to explore novel therapeutic interventions for NETosis in PJI in vitro, and to evaluate the potential diagnostic use of these markers.

An extensive review of the spinal and arthroplasty literature was undertaken to evaluate the effectiveness of local antibiotic irrigation during surgery. The efficacy of antibiotic irrigation for the prevention of acute post-operative infection after total joint arthroplasty was evaluated retrospectively in 2293 arthroplasties (1990 patients) between January 2004 and December 2013. The mean follow-up was 73 months (20 to 139). One surgeon performed all the procedures with minimal post-operative infection.

The intra-operative protocol included an irrigation solution of normal saline with vancomycin 1000 mg/l and polymyxin 250 000 units/l at the rate of 2 l per hour. No patient required re-admission for primary infection or further antibiotic treatment. Two morbidly obese patients (two total hip arthroplasties) developed subcutaneous fat necrosis requiring debridement and one was revised because the deep capsular sutures were contaminated by the draining subcutaneous haematoma. One patient who had undergone total knee arthroplasty had unrecognised damage to the lateral superior geniculate artery and developed a haematoma that became infected secondarily four months after the surgery and underwent revision.

The use of antibiotic irrigation during arthroplasty surgery has been highly effective for the prevention of infection in the author’s practice. However, it should be understood that any routine prophylactic use of antibiotics may result in resistant organisms, and the wise stewardship of the use of antibiotics is an important part of surgical practice.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):23–6.