Summary. A meta-analysis was performed to compare rate of SSI after application of chlorhexidine vs. iodine in total joint arthroplasty. Chlorhexidine had significantly lower odds of SSI. Introduction. Surgical site infections (SSI) are a significant source of morbidity and mortality. The optimal preoperative skin preparation in lower extremity total joint arthroplasty (TJA) remains debatable between chlorhexidine and iodine-containing solutions. This meta-analysis sought compare SSI rates between chlorhexidine cloth application the night before surgery plus povidone-iodine-alcohol (povidone-iodine) solution at surgery or only povidone-iodine at surgery. Methods. A structured literature search was performed using Web of Science, PubMed, and EMBASE databases for randomized clinical trials (RCTs) and comparative studies that evaluated preoperative chlorhexidine-gluconate versus iodine-alcohol exclusively in TJA patients. Databases were searched from database inception to January 2, 2018, and studies were included if they had specific aims and 1) compared preoperative chlorhexidine-gluconate cloths to povidone-iodine at surgery, or 2) if they compared preoperative chlorhexidine-gluconate cloths and povidone-iodine at surgery, to solely povidone-iodine at surgery. The main outcome was deep or superficial SSI at or before 1 year postoperatively. If multiple studies reported the same patient cohort, the more recent study was used. To compare the chlorhexidine versus povidone-iodine groups, pooled odds ratios (OR) and 95% confidence intervals (95% CI) were used to calculate odds of SSI. Results. Four studies involving 2,997 TJA patients were included in this meta-analysis. Three were retrospective cohort studies, and one was a RCT. One retrospective cohort study assessed chlorhexidine to povidone-iodine using a historical control. One RCT compared chlorhexidine to povidone-iodine. The remaining two studies compared chlorhexidine in addition to povidone-iodine, to only povidone-iodine. Bias analysis showed low-to-moderate quality cohort studies and one moderate-quality RCT. Chlorhexidine had significantly lower odds of SSI compared to povidone iodine (OR=0.28; 95%CI: 0.15–0.51; p<0.0001). Conclusion. Preoperative chlorhexidine-gluconate was superior at reducing SSI risk in patients who underwent lower extremity TJA, compared to povidone-iodine. This can potentially lead to decreased morbidity and lower surgical revision rates for infections. For any figures or tables, please contact authors directly

Aims. Arthroplasty surgery of the knee and hip is performed in two to three million patients annually. Periprosthetic joint infections occur in 4% of these patients. Debridement, antibiotics, and implant retention (DAIR) surgery aimed at cleaning the infected prosthesis often fails, subsequently requiring invasive revision of the complete prosthetic reconstruction. Infection-specific imaging may help to guide DAIR. In this study, we evaluated a bacteria-specific hybrid tracer (. 99m. Tc-UBI. 29-41. -Cy5) and its ability to visualize the bacterial load on femoral implants using clinical-grade image guidance methods. Methods. 99m. Tc-UBI. 29-41. -Cy5 specificity for Stapylococcus aureus was assessed in vitro using fluorescence confocal imaging. Topical administration was used to highlight the location of S. aureus cultured on femoral prostheses using fluorescence imaging and freehand single photon emission CT (fhSPECT) scans. Gamma counting and fhSPECT were used to quantify the bacterial load and monitor cleaning with chlorhexidine. Microbiological culturing helped to relate the imaging findings with the number of (remaining) bacteria. Results. Bacteria could be effectively stained in vitro and on prostheses, irrespective of the presence of biofilm. Infected prostheses revealed bacterial presence on the transition zone between the head and neck, and in the screw hole. Qualitative 2D fluorescence images could be complemented with quantitative 3D fhSPECT scans. Despite thorough chlorhexidine treatments, 28% to 44% of the signal remained present in the locations of the infection that were identified using imaging, which included 500 to 2,000 viable bacteria. Conclusion. The hybrid tracer . 99m. Tc-UBI. 29-41. -Cy5 allowed effective bacterial staining. Qualitative real-time fluorescence guidance could be effectively combined with nuclear imaging that enables quantitative monitoring of the effectiveness of cleaning strategies. Cite this article: Bone Joint Res 2023;12(1):72–79

We have summarised the clinical and pathological changes in the knees of three patients in whom aqueous chlorhexidine 0.02% had been used as the irrigation solution during arthroscopically-assisted reconstruction of the anterior cruciate ligament. Even very dilute solutions of chlorhexidine can cause marked chondrolysis of articular cartilage leading to severe permanent damage to the knee. Irrigation solutions should be checked carefully to ensure that their composition is appropriate to the procedure being carried out. Exposure of articular cartilage to chlorhexidine should be avoided

Introduction and Objective. The continued effectiveness of antibiotic loaded bone cements is threatened by antibiotic resistance. The common antiseptic, chlorhexidine (CHX), is a potential alternative to antibiotics in bone cements, but conventional salts are highly soluble, causing burst release and rapid decline to subinhibitory local CHX concentrations. Here, chlorhexidine triphosphate (CHX-TP), a low solubility CHX salt, is investigated as an alternative antimicrobial in PMMA bone cements. The aim was to assess duration of antimicrobial release and antimicrobial efficacy, along with handling, setting and mechanical properties of CHX-TP loaded cements, compared with an existing cement formulation containing gentamicin. Materials and Methods. Palacos R (Heraeus Medical, Newbury, UK) with 0, 1, 4, 7 and 12% CHX-TP (w/w) cements were prepared by combining solid CHX-TP with Palacos R components, and compared with Palacos R+G. All cements were prepared without vacuum and under ISO 5833:2002 conditions. Cements were tested under ISO 5833:2002 for compressive and bending properties, setting time, maximum temperature and doughing time. Antimicrobial release from the cements into deionised water was studied and antimicrobial efficacy of unaged and aged cements against Staphylococcus aureus (ATCC 29213) was assessed using a disc diffusion assay. Results. Compressive strength of CHX-TP loaded cements was not significantly different to Palacos R or Palacos R+G (p > 0.05, all exceeding ISO 5833:2002 minimum of 70 MPa). Mean bending strength was significantly lower with CHX-TP loading (p < 0.05) than bending strength of Palacos R and Palacos R+G, though all bending moduli exceeded the ISO 5833:2002 minimum (1800 MPa). All cements studied were within the ISO 5833:2002 limits for setting time (3 to 15 min), doughing time (≤ 5 min) and maximum temperature (90 . o. C). Mean doughing time for Palacos R, Palacos R+G and Palacos R + 12 % CHX-TP respectively: 52.5 s, 45 s and 45 s. Mean setting time and mean maximum temperature for Palacos R, Palacos R+G and Palacos R + 1, 4, 7 and 12% CHX-TP respectively: 11.00 min (73 . o. C), 11.25 min (72 . o. C), 12.25 min (66 . o. C), 10.50 min (70 . o. C), 10.00 min (70 . o. C), 10.75 min (62 . o. C). Sustained CHX release into deionised water was observed from all Palacos R + CHX-TP cements. Duration varied according to CHX-TP dosing and diminished over time, although to an extent that itself varied with dosing. 1 % CHX-TP ceased releasing CHX at 6.9 weeks; 4 % CHX-TP ceased at 67.7 weeks; 7 % and 12 % CHX-TP were ongoing at 75.5 weeks. Palacos R+G cements ceased releasing detectable levels of gentamicin after 14.4 weeks. Palacos R+G and Palacos R + CHX-TP cement discs showed efficacy against S. aureus (ATCC 29213) when applied as prepared (unaged) to S. aureus bacterial lawns in disc diffusion assays, with CHX-TP cements showing dose dependency. Zone of inhibition (ZOI) size was significantly reduced for Palacos R+G cements and Palacos R + 1% CHX-TP cements after 1 week and 6 weeks aging, compared to ZOI from unaged cements (p < 0.05). ZOI size produced by Palacos R + 4, 7, and 12 % CHX-TP cements did not decline significantly after 6 weeks aging (p > 0.05). Conclusions. CHX-TP can be incorporated into the Palacos R cement matrix up to 12% w/w without deterioration of compressive strength, bending modulus, doughing time, setting time or maximum temperature. Bending strength was significantly reduced at all CHX-TP loadings studied. Palacos R + 4, 7 and 12% CHX-TP cements provided sustained CHX release, exceeding the duration of gentamicin release from Palacos R+G, and showed sustained efficacy against S. Aureus after 6 weeks aging, which was not achieved by Palacos R+G cements

Purpose: Operative wounds are commonly washed with a more or less diluted antiseptic solution to prevent infection or to treated overt infection. Chlorhexidine is widely used. We report the cases of nine patients who developed joint destruction attributed to peroperative irrigation with a chlorhexidine solution. Material and methods: Nine patients (three men and six women) who had undergone surgery in another facility were referred to our unit for unexplained postoperative chondrolysis. The joint localisations were: wrists (n=7) after surgery for a dorsal arthrosynovial cyst (mean age 37 years); elbow (n=1) after surgery for epicondylalgia (age 49 years); shoulder (n=1) after arthroscopy for sub-acromial impingement (age 51 years). The time between surgery and the first consultation in our unit varied from three to nine years (mean five years four months). Persistent stiffness had been noted in the postoperative period with pain at joint mobilisation which worsened progressively. For the patients with chondrolysis of the wrist: the x-rays demonstrated destruction of the radius-first ray joint in one, the medio-carpal joint in four and overall destruction in two. Overall joint destruction was also observed in the elbow and shoulder patients. Search for other causes of joint destruction was negative; infection and inflammatory rheumatoid disease were ruled out. The common feature identified in all patients was joint irrigation with a chlorhexidine solution (Biseptine®). Results: Four of the nine patients underwent surgical treatment: a four-bone arthrodesis with scaphoidectomy was used for the three patients with mediocarpal involvement and a shoulder arthrodesis was performed in one patient. The pathology study demonstrated cartilage defects filled with dense strongly hyalinised acellular tissue. Bacteriological specimens were all negative. Discussion: The chondrolytic effect of chlorhexidine, a member of the biguanide family, was first reported in 1986 with a few cases described with knee involvement. Experimentally, there would be a dose-dependent effect. The mechanism involves a disorganisation of the cell membrane with cartilaginous necrosis and ostocartilaginous resorption. Individual predisposition cannot be ruled out. Conclusion: In light of these observations, it would be advisable to avoid peroperative joint irrigation with chlorhexidine solution

Previous studies have demonstrated higher infection rates following elective procedures on the foot and ankle as compared with procedures involving other area of the body. Previous studies also have documented the difficulty of eliminating bacteria from the forefoot prior to surgery. The purpose of the present study was to ascertain that preoperative chlorhexidine bathing provide significant local flora reduction than placebo in elective foot and ankle surgery. From October 2005 to October 2006, a prospective study was undertaken to evaluate 50 consecutive patients undergoing planned, elective surgery of the foot and ankle. 50 patients were prospectively enrolled and randomly assigned to have preoperative footbath with Chlorhexidine Gluconate (Hibitane) (Group 1) or placebo (Group 2). Culture swabs were taken from all web spaces, nail folds, toe surfaces and proposed surgical incision sites before the preoperative antiseptics bath, during the procedures and immediately completion of surgery. 50 patients were enrolled (mean age: 42.6 years; range: 19–85; F: M = 29:21). 25 patients are assigned to each groups. 100% bacterial isolation preoperatively in both groups prior to antiseptics bathing. In group1, bacteria grew on intraoperative culture in 60% cases and 0% in immediate post-operative culture. In group 2, 96% in intraoperative swab culture and 16% in postoperative swab culture. The intraoperative swab culture bacterial count is statistically significant (p= 0.002). The postoperative swab culture bacterial count is marginally significant (p=0.055) when comparing 2 groups. No complications were recorded in both groups. These data indicate that chlorhexidine provides better reduction in skin flora than placebo. Based of these data, we recommend the use of chlorhexidine footbath as well as the surgical preparatory agent for the foot and ankle surgery

Background: Previous studies have demonstrated higher infection rates following elective procedures on the foot and ankle as compared with procedures involving other area of the body. Previous studies also have documented the difficulty of eliminating bacteria from the forefoot prior to surgery. The purpose of the present study was to ascertain that preoperative chlorhexidine bathing provide significant local flora reduction than placebo in elective foot and ankle surgery. Methods: From October 2005 to October 2006, a prospective study was undertaken to evaluate 50 consecutive patients undergoing planned, elective surgery of the foot and ankle. 50 patients were prospectively enrolled and randomly assigned to have preoperative footbath with Chlorhexidine Gluconate (Hibitane) (Group 1) or placebo (Group 2). Culture swabs were taken from all web spaces, nail folds, toe surfaces and proposed surgical incision sites before the preoperative antiseptics bath, during the procedures and immediately completion of surgery. Results: 50 patients were enrolled (mean age: 42.6 years; range: 19 –85; F: M = 29:21). 25 patients are assigned to each groups. 100% bacterial isolation preoperatively in both groups prior to antiseptics bathing. In group 1, bacteria grew on intraoperative culture in 60% cases and 0% in immediate post-operative culture. In group 2, 96% in intraoperative swab culture and 16% in postoperative swab culture. The intraoperative swab culture bacterial count is statistically significant (p= 0.002). The postoperative swab culture bacterial count is marginally significant (p=0.055) when comparing 2 groups. No complications were recorded in both groups. Conclusions: These data indicate that chlorhexidine provides better reduction in skin flora than placebo. Based of these data, we recommend the use of chlorhexidine footbath as well as the surgical preparatory agent for the foot and ankle surgery

Purpose: Previous studies have demonstrated higher infection rates following elective procedures on the foot and ankle as compared with procedures involving other area of the body. Previous studies also have documented the difficulty of eliminating bacteria from the forefoot prior to surgery. The purpose of the present study was to ascertain that preoperative chlorhexidine bathing provide significant local flora reduction than placebo in elective foot and ankle surgery. Method: From October 2005 to October 2006, a prospective study was undertaken to evaluate 50 consecutive patients undergoing planned, elective surgery of the foot and ankle. 50 patients were prospectively enrolled and randomly assigned to have preoperative footbath with Chlorhexidine Gluconate (Hibitane) (Group 1) or placebo (Group 2). Culture swabs were taken from all web spaces, nail folds, toe surfaces and proposed surgical incision sites before the preoperative antiseptics bath, during the procedures and immediately completion of surgery. Results: 50 patients were enrolled (mean age: 42.6 years; range: 19–85; F: M = 29:21). 25 patients are assigned to each groups. 100% bacterial isolation preoperatively in both groups prior to antiseptics bathing. In group1, bacteria grew on intraoperative culture in 60% cases and 0% in immediate post-operative culture. In group 2, 96% in intraoperative swab culture and 16% in postoperative swab culture. The intraoperative swab culture bacterial count is statistically significant (p= 0.002). The postoperative swab culture bacterial count is marginally significant (p=0.055) when comparing 2 groups. No complications were recorded in both groups. Conclusion: These data indicate that chlorhexidine provides better reduction in skin flora than placebo. Based of these data, we recommend the use of chlorhexidine footbath as well as the surgical preparatory agent for the foot and ankle surgery

Aim. The purpose of this study was to compare the presence of P.acnes on the skin after topical pre-operative application with benzoyl peroxide (BPO) to chlorhexidine soap (CHS) and whether this also affected skin recolonization after surgical preparation and draping. Method. Forty volunteers – twenty-four men and sixteen women were randomized to pre-operative topical treatment at home with either CHS or BPO in the area of a delto-pectoral approach of their left shoulder. The right served as a control. Five skin swabs were taken in a standardized manner on different occasions: before and after topical treatment, after surgical skin preparation and sterile draping and 120 minutes after draping. A fifth sample was taken on the contralateral untreated side as a control when the patient was draped. The draping took place in an operating room with laminar air flow and skin preparation was performed for 2 minutes with 0.5% chlorhexidine solution in 70% ethanol according to the recommendations of the Swedish National Board of Health and Welfare. Bacterial colonies were then analyzed on agar plates by colony forming units (CFU) and surface characteristics. P.acnes were identified with matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry. Results. Topical treatment with BPO significantly reduced the presence of P.acnes as CFU on the skin after surgical preparation. P.acnes was found in 1/20 subjects of the BPO group, and 7/20 in the CHS-group (p<0.044). The results remained after two hours (p<0.048). Topical treatment with BPO before surgical skin preparation significantly decreased the presence of CFU (p-value 0.035). Conclusions. Topical preparation with BPO before shoulder surgery may be effective in reducing P.acnes on the skin and prevent recolonization

We describe six knees in five patients, referred to us after accidental irrigation with chlorhexidine 1% in aqueous solution during arthroscopy. All six knees developed persisting pain, swelling and crepitus with loss of range of movement. Radiographs showed loss of joint space in all three compartments due to extensive chondrolysis, with many loose bodies and synovitis. Histological examination showed partial necrosis of the cartilage, with slight non-specific inflammation and fibrosis of synovial specimens. Care is needed in checking irrigation fluids, and these should have a distinctive colour

Aims

The aim of this study was to determine whether the sequential application of povidone iodine-alcohol (PVI) followed by chlorhexidine gluconate-alcohol (CHG) would reduce surgical wound contamination to a greater extent than PVI applied twice in patients undergoing spinal surgery.

Aim. The origin of surgical site and biomaterial-associated infection is still elusive. Microorganisms contaminating the wound may come from the air, the surgical team, or from the skin of the patient. Prior to surgery the skin of patients is disinfected, but bacteria deeper in the skin (e.g. in sweat glands or sebaceous glands), may not be reached. This study aims to assess a potential role of this intracutaneous bacterial reservoir in biomaterial-associated infection. Method. To study if cutaneous microbiota colonize the wound when released from the skin upon cutting, we isolated, quantified and identified aerobic and anaerobic bacteria from the skin of 99 patients undergoing trauma surgery, before and after skin disinfection, from the knife blades and from the wound directly after the first cut. Results. Ninety-nine percent of the patients were culture-positive before disinfection with chlorhexidine. Of these, 40% were still culture-positive after disinfection. Of these, 54% had a positive culture of the wound after the skin cut. Twenty percent of the patients with a negative culture after disinfection, nevertheless had a positive wound culture after cutting the skin. Staphylococcus epidermidis and Cutibacterium acnes were the most often cultured bacterial species. In 9%, more than 100 bacterial colonies were cultured from the wound, a dose that may cause biomaterial-associated infections. Conclusions. Bacteria residing in the skin and not eradicated by disinfection may enter the surgical wound upon cutting, resulting in contamination which may cause a biomaterial-associated infection. Use of two knifes likely reduces the risk of wound contamination

Aims. Pin-site infection remains a significant problem for patients treated by external fixation. A randomized trial was undertaken to compare the weekly use of alcoholic chlorhexidine (CHX) for pin-site care with an emollient skin preparation in patients with a tibial fracture treated with a circular frame. Methods. Patients were randomized to use either 0.5% CHX or Dermol (DML) 500 emollient pin-site care. A skin biopsy was taken from the tibia during surgery to measure the dermal and epidermal thickness and capillary, macrophage, and T-cell counts per high-powered field. The pH and hydration of the skin were measured preoperatively, at follow-up, and if pin-site infection occurred. Pin-site infection was defined using a validated clinical system. Results. Out of 116 patients who were enrolled in the study, 23 patients (40%) in the CHX group and 26 (44%) in the DML group had at least one bad or ugly pin-site infection. This difference was not statistically significant (p = 0.71). There was no significant relationship between pH or hydration of the skin and pin-site infection. The epidermal thickness was found to be significantly greater in patients who had a pin-site infection compared with those who did not (p = 0.01). Skin irritation requiring a change of treatment occurred in four patients (7%) using CHX, and none using DML. Conclusion. We found no significant difference in the incidence of pin-site infection between the CHX and DML treatment groups. Dermol appeared to offer a small but significant advantage in terms of tolerability. We did not find a significant association between patient or treatment related factors and pin-site infection. It is therefore difficult to make specific recommendations based upon these results. The use of either cleaning agent appears to be appropriate. Cite this article: Bone Joint J 2021;103-B(2):279–285

Introduction. Periprosthetic infection following lower extremity total joint arthroplasty often requires multiple surgical procedures and imposes a marked economic burden on the patient and hospital. The purpose of this study was to evaluate the incidence of surgical site infections in total joint arthroplasty patients who used an advance at-home pre-admission cutaneous preparation protocol and to compare these results to a cohort of patients who underwent standard in-hospital peri-operative preparation only. Methods. Patients scheduled for surgery were given two packets of 2% chlorhexidine gluconate-impregnated cloths, with instructions for use the evening before and morning of surgery. Records between 2007 and 2010 were reviewed to identify deep incisional and periprosthetic infections. The Centers for Disease Control and Prevention and the Musculoskeletal Infection Society definitions were used for diagnosis. Results. A significantly lower incidence of surgical site infections was found in the chlorhexidine preparation group. For total hip arthroplasty, three surgical site infections occurred in 557 patients (0.5%) of the chlorhexidine group compared to 32 of 1,901 patients (1.7%) in the control group. For total knee arthroplasty, three surgical site infections occurred in 478 patients (0.6%) who used the chlorhexidine cloths, compared to 38 surgical site infections in 1,735 patients (2.2%) in the control group. Discussion. The use of an advance pre-admission chlorhexidine protocol significantly reduced the incidence of surgical site infections in total joint arthroplasty when compared to patients who did not use this protocol. This study validates prior studies in orthopaedics suggesting this as an effective method to prevent periprosthetic infections

Hypochlorous acid (HOCl) is a potent anti-bacterial agent which could reduce periprosthetic joint infection. Early infection complications in joint replacements are often considered to be due to local contamination at the time of surgery and result in a significant socioeconomic cost. Current theatre cleaning procedures produce “clean” operating theatres which still contain bacteria (colony forming units, CFU). Reducing this bacterial load may reduce local contamination at the time of surgery. HOCl is produced naturally in the human neutrophil and has been implicated as the primary agent involved in bacterial killing during this process. In vitro research confirms its efficacy against essentially all clinically relevant bacteria. The recent advent of commercial production of HOCl, delivered as a fog, has resulted in extensive use in the food industry. Reported lack of corrosion and high anti-bacterial potency are seen as two key factors for the use of HOCl in the orthopaedic environment. Prior work by the authors comparing human cell toxicity of HOCl, chlorhexidine and iodine solutions shows favourable results. This study evaluates use of neutral HOCl applied as a dry room fog to decrease bacteria in the operating theatre environment. Using an animal operating theatre as the test site, bacterial swabs were taken from ten 100cm. 2. sample areas before standard cleaning with detergent, after standard cleaning, and again after 60 minutes exposure to HOCl fog. After standard cleaning, 6 of 10 sample sites recorded significant bacterial growth (>10 CFU/100cm. 2. ). After exposure to HOCl fog, growth in all 10 sites was below detection limits (<10 CFU/100cm. 2. ). This was repeated with specific exposure to Staphylococcus aureus and Escherichia coli. We can conclude that HOCl is effective when used as a fogging agent to reduce bacterial loading within an operating theatre environment and as such has significant potential to reduce intraoperative contamination and periprosthetic infection

We report a systematic review and meta-analysis of published randomised and quasi-randomised trials evaluating the efficacy of pre-operative skin antisepsis and cleansing techniques in reducing foot and ankle skin flora. The post-preparation culture number (Post-PCN) was the primary outcome. The data were evaluated using a modified version of the Cochrane Collaboration’s tool. We identified eight trials (560 participants, 716 feet) that met the inclusion criteria. There was a significant difference in the proportions of Post-PCN between hallux nailfold (HNF) and toe web spaces (TWS) sites: 0.47 vs 0.22, respectively (95% confidence interval (CI) 0.182937 to 0.304097; p < 0.0001). Meta-analyses showed that alcoholic chlorhexidine had better efficacy than alcoholic povidone-iodine (PI) at HNF sites (risk difference 0.19 (95% CI 0.08 to 0.30); p = 0.0005); a two-step intervention using PI scrub and paint (S& P) followed by alcohol showed significantly better efficacy over PI (S& P) alone at TWS sites (risk difference 0.13 (95% CI 0.02 to 0.24); p = 0.0169); and a two-step intervention using chlorhexidine scrub followed by alcohol showed significantly better efficacy over PI (S& P) alone at the combined (HNF with TWS) sites (risk difference 0.27 (95% CI 0.13 to 0.40); p < 0.0001). No significant difference was found between cleansing techniques. Cite this article: Bone Joint J 2013;95-B:498–503

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

Post-surgical wound infections following total hip or knee arthroplasties can be a potentially catastrophic complication for the patient. Currently, several preventative measures exist to help combat this complication. One such method is skin disinfection with preadmission cutaneous chlorhexidine preparation. Although efficacious in reducing surgical site infections during total joint arthroplasty, orthopaedists should be aware of discrepancies between hip and knee arthroplasty. For example, Kapadia et al. performed a prospective study which evaluated the use of preadmission cutaneous chlorhexidine preparation on the reduction of surgical site infections following total hip arthroplasty; they found that there was a 3-fold higher relative risk of developing infection in patients who did not receive the chlorhexidine preparation as compared to those who did. In a similar study performed for total knee arthroplasty, the same authors founds a 6-fold higher relative risk of developing infection, which equated to double the risk as compared to total hip arthroplasty. In a study by Lewis et al. regarding timing to diagnosis of surgical site infections in post-hip and knee arthroplasties, the authors found a longer median time to diagnosis post-knee arthroplasty as compared to hip arthroplasty (25 vs. 42 days, p= <0.001). These finding suggest that orthopaedists should recognise that “A knee is not a hip” with regards to surgical site infections and should be aware of the discrepancies that exist between the two

Aims. Of growing concern in arthroplasty is the emergence of atypical infections, particularly Cutibacterium (formerly Propionibacterium) sp. infections. Currently, the dermal colonization rate of Cutibacterium about the hip is unknown. Therefore, the aim of this study was to investigate colonization rates of Cutibacterium sp. at locations approximating anterior and posterolateral approaches to the hip joint. Methods. For this non-randomized non-blinded study, 101 adult patients scheduled for hip or knee surgery were recruited. For each, four 3 mm dermal punch biopsies were collected after administration of anaesthesia, but prior to antibiotics. Prebiopsy skin preparation consisted of a standardized preoperative 2% chlorhexidine skin cleansing protocol and an additional 70% isopropyl alcohol mechanical skin scrub immediately prior to biopsy collection. Two skin samples 10 cm apart were collected from a location approximating a standard direct anterior skin incision, and two samples 10 cm apart were collected from a lateral skin incision (suitable for posterior, direct-lateral, or anterolateral approaches). Samples were cultured for two weeks using a protocol optimized for Cutibacterium. Results. A total of 23 out of 404 cultures (collected from 101 patients) were positive for a microorganism, with a total of 22 patients having a positive culture (22%). Overall, 15 of the cultures in 14 patients were positive for Cutibacterium sp. (65%), of which Cutibacterium acnes comprised the majority (n = 13; 87%). Other isolated microorganisms include coagulase-negative Staphylococcus (n = 6), Clostridium (n = 1), and Corynebacterium (n = 1). Of all positive cultures, 15 were obtained from the anterior location (65%), of which seven (60%) were from the most proximal biopsy location. However, these findings were not statistically significant (anterior vs lateral, p = 0.076; proximal vs distal, p =0.238). Conclusion. Approximately 14% (14/101) of the patients demonstrated a positive Cutibacterium colonization about the hip, the majority anteriorly. Given the high colonization rate of Cutibacterium, alternative skin preparations for total hip arthroplasty should be considered. Cite this article: Bone Joint J 2020;102-B(7 Supple B):52–56