Aims. The aim of this study was to perform the first population-based description of the epidemiological and health economic burden of fracture-related infection (FRI). Methods. This is a retrospective cohort study of operatively managed orthopaedic trauma patients from 1 January 2007 to 31 December 2016, performed in Queensland, Australia. Record linkage was used to develop a person-centric, population-based dataset incorporating routinely collected administrative, clinical, and health economic information. The FRI group consisted of patients with International Classification of Disease 10th Revision diagnosis codes for deep infection associated with an implanted device within two years following surgery, while all others were deemed not infected. Demographic and clinical variables, as well as healthcare utilization costs, were compared. Results. There were 111,402 patients operatively managed for orthopaedic trauma, with 2,775 of these (2.5%) complicated by FRI. The development of FRI had a statistically significant association with older age, male sex, residing in rural/remote areas, Aboriginal or Torres Strait Islander background, lower socioeconomic status, road traffic accident, work-related injuries, open fractures, anatomical region (lower limb, spine, pelvis), high injury severity, requiring soft-tissue coverage, and medical comorbidities (univariate analysis). Patients with FRI had an eight-times longer median inpatient length of stay (24 days vs 3 days), and a 2.8-times higher mean estimated inpatient hospitalization cost (AU$56,565 vs AU$19,773) compared with uninfected patients. The total estimated inpatient cost of the FRI cohort to the healthcare system was AU$156.9 million over the ten-year period. Conclusion. The results of this study advocate for improvements in trauma care and infection management, address social determinants of health, and highlight the upside potential to improve prevention and treatment strategies. Cite this article: Bone Joint J 2024;106-B(1):77–85

Aims. To evaluate the impact of negative pressure wound therapy (NPWT) on the odds of having deep infections and health-related quality of life (HRQoL) following open fractures. Methods. Patients from the Fluid Lavage in Open Fracture Wounds (FLOW) trial with Gustilo-Anderson grade II or III open fractures within the lower limb were included in this secondary analysis. Using mixed effects logistic regression, we assessed the impact of NPWT on deep wound infection requiring surgical intervention within 12 months post-injury. Using multilevel model analyses, we evaluated the impact of NPWT on the Physical Component Summary (PCS) of the 12-Item Short-Form Health Survey (SF-12) at 12 months post-injury. Results. After applying inverse probability treatment weighting to adjust for the influence of injury characteristics on type of dressing used, 1,322 participants were assessed. The odds of developing a deep infection requiring operative management within 12 months of initial surgery was 4.52-times higher in patients who received NPWT compared to those who received a standard wound dressing (95% confidence interval (CI) 1.84 to 11.12; p = 0.001). Overall, 1,040 participants were included in our HRQoL analysis, and those treated with NPWT had statistically significantly lower mean SF-12 PCS post-fracture (p < 0.001). These differences did not reach the minimally important difference for the SF-12 PCS. Conclusion. Our analysis found that patients treated with NPWT had higher odds of developing a deep infection requiring operative management within 12 months post-fracture. Due to possible residual confounding with the worst cases being treated with NPWT, we are unable to determine if NPWT has a negative effect or is simply a marker of worse injuries or poor access to early soft-tissue coverage. Regardless, our results suggest that the use of this treatment requires further evaluation. Cite this article: Bone Jt Open 2022;3(3):189–195

Aims. Deep surgical site infection (SSI) is common after lower limb fracture. We compared the diagnosis of deep SSI using alternative methods of data collection and examined the agreement of clinical photography and in-person clinical assessment by the Centers for Disease Control and Prevention (CDC) criteria after lower limb fracture surgery. Methods. Data from two large, UK-based multicentre randomized controlled major trauma trials investigating SSI and wound healing after surgical repair of open lower limb fractures that could not be primarily closed (UK WOLLF), and surgical incisions for fractures that were primarily closed (UK WHiST), were examined. Trial interventions were standard wound care management and negative pressure wound therapy after initial surgical debridement. Wound outcomes were collected from 30 days to six weeks. We compared the level of agreement between wound photography and clinical assessment of CDC-defined SSI. We are also assessed the level of agreement between blinded independent assessors of the photographs. Results. Rates of CDC-defined deep SSI were 7.6% (35/460) after open fracture and 6.3% (95/1519) after closed incisional repair. Photographs were obtained for 77% and 73% of WOLLF and WHiST cohorts respectively (all participants n = 1,478). Agreement between photographic-SSI and CDC-SSI was fair for open fracture wounds (83%; k = 0.27 (95% confidence interval (CI) 0.14 to 0.42)) and for closed incisional wounds (88%; k = 0.29 (95% CI 0.20 to 0.37)) although the rate of photographically detected deep SSIs was twice as high as CDC-SSI (12% vs 6%). Agreement between different assessors for photographic-SSI (WOLLF 88%, k = 0.63 (95% CI 0.52 to 0.72); WHiST 89%; k = 0.61 (95% CI 0.54 to 0.69)); and wound healing was good (WOLLF 90%; k = 0.80 (95% CI 0.73 to 0.86); WHiST 87%; k = 0.57 (95% CI 0.50 to 0.64)). Conclusion. Although wound photography was feasible within the research context and inter-rater assessor agreement substantial, digital photographs used in isolation overestimated deep SSI rates, when compared to CDC criteria. Wound photography should not replace clinical assessment in pragmatic trials but may be useful for screening purposes where surgical infection outcomes are paramount. Cite this article: Bone Joint J 2021;103-B(12):1802–1808

Aims. This study aimed to investigate the role of quantitative histological analysis in the diagnosis of fracture-related infection (FRI). Patients and Methods. The clinical features, microbiology culture results, and histological analysis in 156 surgically treated nonunions were used to stratify the likelihood of associated infection. There were 64 confirmed infected nonunions (one or more confirmatory criteria: pus, sinus, and bacterial growth in two or more samples), 66 aseptic nonunions (no confirmatory criteria), and 26 possibly infected nonunions (pathogen identified from a single specimen and no confirmatory criteria). The histological inflammatory response was assessed by average neutrophil polymorph (NPs) counts per high-power field (HPF) and compared with the established diagnosis. Results. Assuming a cut-off of over five neutrophils per high-power field to diagnose septic nonunion, there was 80% sensitivity and 100% specificity (accuracy 90%). Using a cut-off of no neutrophils seen in any high-power field to diagnose aseptic nonunion, there was a sensitivity of 85% and a specificity of 98% (accuracy 92%). Conclusion. Histology can be used in a bimodal fashion as a diagnostic test for FRI. The presence of more than five NPs/HPF had a positive predictive value for infected nonunion of 100%, while the complete absence of any NPs is almost always indicative of an aseptic nonunion (positive predictive value of 98%). Cite this article: Bone Joint J 2018;100-B:966–72

Objectives. A successful outcome following treatment of nonunion requires the correct identification of all of the underlying cause(s) and addressing them appropriately. The aim of this study was to assess the distribution and frequency of causative factors in a consecutive cohort of nonunion patients in order to optimise the management strategy for individual patients presenting with nonunion. Methods. Causes of the nonunion were divided into four categories: mechanical; infection; dead bone with a gap; and host. Prospective and retrospective data of 100 consecutive patients who had undergone surgery for long bone fracture nonunion were analysed. Results. A total of 31% of patients had a single attributable cause, 55% had two causes, 14% had three causes and 1% had all four. Of those (31%) with only a single attributable cause, half were due to a mechanical factor and a quarter had dead bone with a gap. Mechanical causation was found in 59% of all patients, dead bone and a gap was present in 47%, host factors in 43% and infection was a causative factor in 38% of patients. In all, three of 58 patients (5%) thought to be aseptic and two of nine (22%) suspected of possible infection were found to be infected. A total of 100% of previously treated patients no longer considered to have ongoing infection, had multiple positive microbiology results. Conclusion. Two thirds of patients had multiple contributing factors for their nonunion and 5% had entirely unexpected infection. This study highlights the importance of identifying all of the aetiological factors and routinely testing tissue for infection in treating nonunion. It raises key points regarding the inadequacy of a purely radiographic nonunion classification system and the variety of different definitions for atrophic nonunion in the current mainstream classifications used for nonunion. Cite this article: L. Mills, J. Tsang, G. Hopper, G. Keenan, A. H. R. W. Simpson. The multifactorial aetiology of fracture nonunion and the importance of searching for latent infection. Bone Joint Res 2016;5:512–519. DOI: 10.1302/2046-3758.510.BJR-2016-0138

Aims. To determine whether there is any difference in infection rate at 90 days between trauma operations performed in laminar flow and plenum ventilation, and whether infection risk is altered following the installation of laminar flow (LF). Patients and Methods. We assessed the impact of plenum ventilation (PV) and LF on the rate of infection for patients undergoing orthopaedic trauma operations. All NHS hospitals in England with a trauma theatre(s) were contacted to identify the ventilation system which was used between April 2008 and March 2013 in the following categories: always LF, never LF, installed LF during study period (subdivided: before, during and after installation) and unknown. For each operation, age, gender, comorbidity, socio-economic deprivation, number of previous trauma operations and surgical site infection within 90 days (SSI90) were extracted from England’s national hospital administrative Hospital Episode Statistics database. Crude and adjusted odds ratios (OR) were used to compare ventilation groups using hierarchical logistic regression. Subanalysis was performed for hip hemiarthroplasties. Results. A total of 803 065 trauma operations were performed during this time; 19 hospitals installed LF, 124 already had LF, 13 had PV and the type of ventilation was unknown in 28. Patient characteristics were similar between the groups. The rate of SSI90 was similar for always LF and PV (2.7% and 2.4%). For hemiarthroplasties of the hip, the rates of SSI90 were significantly higher for LF compared with PV (3.8% and 2.6%, OR 1.45, p = 0·001). Hospitals installing LF did not see any statistically significant change in the rate of SSI90. Conclusion. The results of this observational study imply that infection rate is similar when orthopaedic trauma surgery is performed in LF and PV, and is unchanged by installing LF in a previously PV theatre. Cite this article: Bone Joint J 2016;98-B:1262–9

Most animal studies indicate that early irrigation and debridement reduce infection after an open fracture. Unfortunately, these studies often do not involve antibiotics. Clinical studies indicate that the timing of initial debridement does not affect the rate of infection but these studies are observational and fraught with confounding variables. The purpose of this study was to control these variables using an animal model incorporating systemic antibiotics and surgical treatment. We used a rat femur model with a defect which was contaminated with Staphylococcus aureus and treated with a three-day course of systemic cefazolin (5 mg/kg 12-hourly) and debridement and irrigation, both of which were initiated independently at two, six and 24 hour time points. After 14 days the bone and hardware were harvested for separate microbiological analysis. No animal that received antibiotics and surgery two hours after injury had detectable bacteria. When antibiotics were started at two hours, a delay in surgical treatment from two to six hours significantly increased the development of infection (p = 0.047). However, delaying surgery to 24 hours increase the rate of infection, but not significantly (p = 0.054). The timing of antibiotics had a more significant effect on the proportion of positive samples than earlier surgery. Delaying antibiotics to six or 24 hours had a profoundly detrimental effect on the infection rate regardless of the timing of surgery. These findings are consistent with the concept that bacteria progress from a vulnerable planktonic form to a treatment-resistant biofilm

We undertook a retrospective case-control study to assess the clinical variables associated with infections in open fractures. A total of 1492 open fractures were retrieved; these were Gustilo and Anderson grade I in 663 (44.4%), grade II in 370 (24.8%), grade III in 310 (20.8%) and unclassifiable in 149 (10.0%). The median duration of prophylaxis was three days (interquartile range (IQR) 1 to 3), and the median number of surgical interventions was two (1 to 9). We identified 54 infections (3.6%) occurring at a median of ten days (IQR 5 to 20) after trauma. Pathogens intrinsically resistant to the empirical antibiotic regimen used (enterococci, Enterobacter spp, Pseudomonas spp) were documented in 35 of 49 cases (71%). In multivariable regression analyses, grade III fractures and vascular injury or compartment syndrome were significantly associated with infection. Overall, compared with one day of antibiotic treatment, two to three days (odds ratio (OR) 0.6 (95% confidence interval (CI) 0.2 to 2.0)), four to five days (OR 1.2 (95% CI 0.3 to 4.9)), or > five days (OR 1.4 (95% CI 0.4 to 4.4)) did not show any significant differences in the infection risk. These results were similar when multivariable analysis was performed for grade III fractures only (OR 0.3 (95% CI 0.1 to 3.4); OR 0.6 (95% CI 0.2 to 2.1); and OR 1.7 (95% CI 0.5 to 6.2), respectively). Infection in open fractures is related to the extent of tissue damage but not to the duration of prophylactic antibiotic therapy. Even for grade III fractures, a one-day course of prophylactic antibiotics might be as effective as prolonged prophylaxis. Cite this article: Bone Joint J 2013;95-B:831–7

Aims. Deep surgical site infection (SSI) remains an unsolved problem after hip fracture. Debridement, antibiotic, and implant retention (DAIR) has become a mainstream treatment in elective periprosthetic joint infection; however, evidence for DAIR after infected hip hemiarthroplaty is limited. Methods. Patients who underwent a hemiarthroplasty between March 2007 and August 2018 were reviewed. Multivariable binary logistic regression was performed to identify and adjust for risk factors for SSI, and to identify factors predicting a successful DAIR at one year. Results. A total of 3,966 patients were identified. The overall rate of SSI was 1.7% (51 patients (1.3%) with deep SSI, and 18 (0.45%) with superficial SSI). In all, 50 patients underwent revision surgery for infection (43 with DAIR, and seven with excision arthroplasty). After adjustment for other variables, only concurrent urinary tract infection (odds ratio (OR) 2.78, 95% confidence interval (CI) 1.57 to 4.92; p < 0.001) and increasing delay to theatre for treatment of the fracture (OR 1.31 per day, 95% CI 1.12 to 1.52; p < 0.001) were predictors of developing a SSI, while a cemented arthroplasty was protective (OR 0.54, 95% CI 0.31 to 0.96; p = 0.031). In all, nine patients (20.9%) were alive at one year with a functioning hemiarthroplasty following DAIR, 20 (46.5%) required multiple surgical debridements after an initial DAIR, and 18 were converted to an excision arthroplasty due to persistent infection, with six were alive at one year. The culture of any gram-negative organism reduced success rates to 12.5% (no cases were successful with methicillin-resistant Staphylococcus aureus or Pseudomonas infection). Favourable organisms included Citrobacter and Proteus (100% cure rate). The all-cause mortality at one year after deep SSI was 55.87% versus 24.9% without deep infection. Conclusion. Deep infection remains a devastating complication regardless of the treatment strategy employed. Success rates of DAIR are poor compared to total hip arthroplasty, and should be reserved for favourable organisms in patients able to tolerate multiple surgical procedures. Cite this article: Bone Jt Open 2021;2(11):958–965

Aims. Musculoskeletal infection is a devastating complication in both trauma and elective orthopaedic surgeries that can result in significant morbidity. Aim of this study was to assess the effectiveness and complications of local antibiotic impregnated dissolvable synthetic calcium sulphate beads (Stimulan Rapid Cure) in the hands of different surgeons from multiple centres in surgically managed bone and joint infections. Methods. Between January 2019 and December 2022, 106 patients with bone and joint infections were treated by five surgeons in five hospitals. Surgical debridement and calcium sulphate bead insertion was performed for local elution of antibiotics in high concentration. In all, 100 patients were available for follow-up at regular intervals. Choice of antibiotic was tailor made for each patient in consultation with microbiologist based on the organism grown on culture and the sensitivity. In majority of our cases, we used a combination of vancomycin and culture sensitive heat stable antibiotic after a thorough debridement of the site. Primary wound closure was achieved in 99 patients and a split skin graft closure was done in one patient. Mean follow-up was 20 months (12 to 30). Results. Overall, six out of 106 patients (5.6%) presented with sepsis and poorly controlled comorbid conditions, and died in the hospital within few days of index surgery. Out of the remaining 100 patients, control of infection was achieved in 95 patients (95%). Persistence of infection was noted in five (5%) patients. Out of these 95 patients that had good control of infection, four patients (4.2%) with gap nonunion needed Masquelet procedure to achieve union. Conclusion. Our multicentre experience confirmed that surgical debridement along with calcium sulphate bead insertion was effective in treating bone and joint infections without any side effects and complications. Cite this article: Bone Jt Open 2023;4(7):516–522

Aims. The aim of the present study was to assess the outcomes of the induced membrane technique (IMT) for the management of infected segmental bone defects, and to analyze predictive factors associated with unfavourable outcomes. Methods. Between May 2012 and December 2020, 203 patients with infected segmental bone defects treated with the IMT were enrolled. The digital medical records of these patients were retrospectively analyzed. Factors associated with unfavourable outcomes were identified through logistic regression analysis. Results. Among the 203 enrolled patients, infection recurred in 27 patients (13.3%) after bone grafting. The union rate was 75.9% (154 patients) after second-stage surgery without additional procedures, and final union was achieved in 173 patients (85.2%) after second-stage surgery with or without additional procedures. The mean healing time was 9.3 months (3 to 37). Multivariate logistic regression analysis of 203 patients showed that the number (≥ two) of debridements (first stage) was an independent risk factor for infection recurrence and nonunion. Larger defect sizes were associated with higher odds of nonunion. After excluding 27 patients with infection recurrence, multivariate analysis of the remaining 176 patients suggested that intramedullary nail plus plate internal fixation, smoking, and an allograft-to-autograft ratio exceeding 1:3 adversely affected healing time. Conclusion. The IMT is an effective method to achieve infection eradication and union in the management of infected segmental bone defects. Our study identified several risk factors associated with unfavourable outcomes. Some of these factors are modifiable, and the risk of adverse outcomes can be reduced by adopting targeted interventions or strategies. Surgeons can fully inform patients with non-modifiable risk factors preoperatively, and may even use other methods for bone defect reconstruction. Cite this article: Bone Joint J 2024;106-B(6):613–622

Our aim was to explore factors associated with early post operative infection for surgically managed base of 4th/5th metacarpal fractures. We hypothesised that K-wires crossing the 4th and 5th carpometacarpal joint (CMCJ) would be associated with an increased risk of post-operative infection. Data from consecutive patients requiring surgical fixation for a base of 4th/5th metacarpal fracture from October 2016 to May 2021 were collected. Patient demographics, time to surgery, length of surgery, operator experience, use of tourniquet, intra-operative antibiotics, number and thickness of K-wire used, as well as whether or not the K-wires crossed CMCJ joints were recorded. Factors associated with post operative infection were assessed using Chi Squared test and univariable logistic regression using R studio. Of 107 patients, 10 (9.3%) suffered post operative infection. Time to surgery (p 0.006) and length of operation (p=0.005) were higher in those experiencing infection. There was a trend towards higher risk of infection seen in those who had K-wires crossed (p=0.06). On univariable analysis, patients who had wires crossed were >7 times more likely to experience infection than those who didn't (OR 7.79 (95% CI, 1.39 - 146.0, p=0.056). Age, smoking, K-wire size, number of K-wires used, intraoperative antibiotics, tourniquet use and operator experience were not associated with infection. In patients with a base of 4th/5th metacarpal fractures requiring surgical fixation, we find an increased risk of post-operative infection associated with K-wires crossing the CMCJ, which has implications for surgical technique. Larger prospective studies would be useful in further delineating these findings

Aims. Fracture-related infections (FRIs) are a devastating complication of fracture management. However, the impact of FRIs on mental health remains understudied. The aim of this study was a longitudinal evaluation of patients’ psychological state, and expectations for recovery comparing patients with recurrent FRI to those with primary FRI. Methods. A prospective longitudinal study was conducted at a level 1 trauma centre from January 2020 to December 2022. In total, 56 patients treated for FRI were enrolled. The ICD-10 symptom rating (ISR) and an expectation questionnaire were assessed at five timepoints: preoperatively, one month postoperatively, and at three, six, and 12 months. Results. Recurrent FRI cases consistently exceeded the symptom burden threshold (0.60) in ISR scores at all assessment points. The difference between preoperative-assessed total ISR scores and the 12-month follow-up was not significant in either group, with 0.04 for primary FRI (p = 0.807) and 0.01 for recurrent FRI (p = 0.768). While primary FRI patients showed decreased depression scores post surgery, recurrent FRI cases experienced an increase, reaching a peak at 12 months (1.92 vs 0.94; p < 0.001). Anxiety scores rose for both groups after surgery, notably higher in recurrent FRI cases (1.39 vs 1.02; p < 0.001). Moreover, patients with primary FRI reported lower expectations of returning to normal health at three (1.99 vs 1.11; p < 0.001) and 12 months (2.01 vs 1.33; p = 0.006). Conclusion. The findings demonstrate the significant psychological burden experienced by individuals undergoing treatment for FRI, which is more severe in recurrent FRI. Understanding the psychological dimensions of recurrent FRIs is crucial for comprehensive patient care, and underscores the importance of integrating psychological support into the treatment paradigm for such cases. Cite this article: Bone Jt Open 2024;5(7):621–627

Aims. This study aims to estimate economic outcomes associated with 30-day deep surgical site infection (SSI) from closed surgical wounds in patients with lower limb fractures following major trauma. Methods. Data from the Wound Healing in Surgery for Trauma (WHiST) trial, which collected outcomes from 1,547 adult participants using self-completed questionnaires over a six-month period following major trauma, was used as the basis of this empirical investigation. Associations between deep SSI and NHS and personal social services (PSS) costs (£, 2017 to 2018 prices), and between deep SSI and quality-adjusted life years (QALYs), were estimated using descriptive and multivariable analyses. Sensitivity analyses assessed the impact of uncertainty surrounding components of the economic analyses. Results. Compared to participants without deep SSI, those with deep SSI had higher mean adjusted total NHS and PSS costs (adjusted mean difference £1,577 (95% confidence interval (CI) -951 to 4,105); p = 0.222), and lower mean adjusted QALYs (adjusted mean difference -0.015 (95% CI -0.032 to 0.002); p = 0.092) over six months post-injury, but this difference was not statistically significant. The results were robust to the sensitivity analyses performed. Conclusion. This study found worse economic outcomes during the first six months post-injury in participants who experience deep SSI following orthopaedic surgery for major trauma to the lower limb. However, the increase in cost associated with deep SSI was less than previously reported in the orthopaedic trauma literature. Cite this article: Bone Jt Open 2022;3(5):398–403

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

Aims. The aim of this study was to evaluate the diagnostic value of preoperative serum CRP, white blood cell count (WBC), percentage of neutrophils (%N), and neutrophil to lymphocyte ratio (NLR) when using the fracture-related infection (FRI) consensus definition. Methods. A cohort of 106 patients having surgery for suspected septic nonunion after failed fracture fixation were studied. Blood samples were collected preoperatively, and the concentration of serum CRP, WBC, and differential cell count were analyzed. The areas under the curve (AUCs) of diagnostic tests were compared using the z-test. Regression trees were constructed and internally cross-validated to derive a simple diagnostic decision tree. Results. Using the FRI consensus definition, 46 patients (43%) were identified as infected. Sensitivity, specificity, and AUC of CRP were 67% (95% confidence interval (CI) 52% to 80%), 61% (95% CI 47% to 74%), and 0.64 (95% CI 0.54 to 0.74); of WBC count were 17% (95% CI 9% to 31%), 95% (95% CI 86% to 99%), and 0.57 (95% CI 0.50 to 0.62); of %N 13% (95% CI 6% to 26%), 87% (95% CI 76% to 93%), and 0.50 (95% CI 0.43 to 0.56); and of NLR 28% (95% CI 17% to 43%), 80% (95% CI 68% to 88%), and 0.54 (95% CI 0.46 to 0.63), respectively. A better performance of serum CRP was shown in comparison to the leucocyte count (p = 0.006), %N (p < 0.001), and NLR (p = 0.001). A statistically lower serum CRP level was shown in patients with an infection caused by a low virulence microorganism in comparison to high virulence bacteria (p = 0.008). We found that a simple decision tree approach using only low serum neutrophils (< 3.615 × 10. 9. /l) and low CRP (< 2.45 mg/l) may allow better identification of aseptic cases. Conclusion. The evaluated serum inflammatory markers showed limited diagnostic value in the preoperative diagnosis of FRI when using the uniform FRI Consensus Definition. Therefore, they should remain as suggestive criteria in diagnosing FRI. Although CRP showed a higher performance in comparison to the other serum markers, it is insufficiently accurate to diagnose a septic nonunion, especially when caused by low virulence microorganisms. Cite this article: Bone Joint J 2020;102-B(7):904–911

Aims. Monocyte-lymphocyte ratio (MLR) or neutrophil-lymphocyte ratio (NLR) are useful for diagnosing periprosthetic joint infection (PJI), but their diagnostic values are unclear for screening fixation-related infection (FRI) in patients for whom conversion total hip arthroplasty (THA) is planned after failed internal fixation for femoral neck fracture. Methods. We retrospectively included 340 patients who underwent conversion THA after internal fixation for femoral neck fracture from January 2008 to September 2020. Those patients constituted two groups: noninfected patients and patients diagnosed with FRI according to the 2013 International Consensus Meeting Criteria. Receiver operating characteristic (ROC) curves were used to determine maximum sensitivity and specificity of these two preoperative ratios. The diagnostic performance of the two ratios combined with preoperative CRP or ESR was also evaluated. Results. The numbers of patients with and without FRI were 19 (5.6%) and 321 (94.4%), respectively. Areas under the ROC curve for diagnosing FRI were 0.763 for MLR, 0.686 for NLR, 0.905 for CRP, and 0.769 for ESR. Based on the Youden index, the optimal predictive cutoffs were 0.25 for MLR and 2.38 for NLR. Sensitivity and specificity were 78.9% and 71.0% for MLR, and 78.9% and 56.4% for NLR, respectively. The combination of CRP with MLR showed a sensitivity of 84.2% and specificity of 94.6%, while the corresponding values for the combination of CRP with NLR were 89.5% and 91.5%, respectively. Conclusion. The presence of preoperative FRI among patients undergoing conversion THA after internal fixation for femoral neck fracture should be determined. The combination of preoperative CRP with NLR is sensitive tool for screening FRI in those patients. Cite this article: Bone Joint J 2021;103-B(9):1534–1540

Aims. This study sought to compare the rate of deep surgical site infection (SSI), as measured by the Centers for Disease Control and Prevention (CDC) definition, after surgery for a fracture of the hip between patients treated with standard dressings and those treated with incisional negative pressure wound therapy (iNPWT). Secondary objectives included determining the rate of recruitment and willingness to participate in the trial. Methods. The study was a two-arm multicentre randomized controlled feasibility trial that was embedded in the World Hip Trauma Evaluation cohort study. Any patient aged > 65 years having surgery for hip fracture at five recruitment centres in the UK was considered to be eligible. They were randomly allocated to have either a standard dressing or iNPWT after closure of the wound. The primary outcome measure was deep SSI at 30 and 90 days, diagnosed according to the CDC criteria. Secondary outcomes were: rate of recruitment; further surgery within 120 days; health-related quality of life (HRQoL) using the EuroQol five-level five-dimension questionnaire (EQ-5D-5L); and related complications within 120 days as well as mobility and residential status at this time. Results. A total of 462 valid randomizations were carried out (232 and 230 in the standard dressing and iNPWT groups, respectively). In the standard dressing group, 14 of 218 patients (6.4%) developed deep SSI. In the iNPWT group, four of 214 patients (1.9%) developed deep SSI. This gives a total rate of SSI of 4.2% (95% confidence interval (CI) 2.7% to 6.5%). Patients and surgeons were willing to participate in the study with 462 patients being recruited from a possible 749 (62.3%). Conclusion. The rate of deep SSI 30 days after surgery for a fracture of the hip was 4%, which makes a study comparing the clinical effectiveness of standard dressings and iNPWT feasible. Cite this article: Bone Joint J 2021;103-B(4):755–761

Antimicrobial resistance (AMR) is projected to result in 10 million deaths every year globally by 2050. Without urgent action, routine orthopaedic operations could become high risk and musculoskeletal infections incurable in a “post-antibiotic era.” However, current methods of studying AMR processes including bacterial biofilm formation are 2D in nature, and therefore unable to recapitulate the 3D processes within in vivo infection. Within this study, 3D printing was applied for the first time alongside a custom-developed bioink to bioprint 3D bacterial biofilm constructs from clinically relevant species including Staphylococcus aureus (MSSA), Methicillin-resistant staphylococcus aureus (MRSA), Escherichia coli and Pseudomonas aeruginosa. Bacterial viability and biofilm formation in bioprinted constructs was excellent, with confocal laser scanning microscopy (CSLM) used to demonstrate biofilm production and maturation over 28 days. Bioprinted 3D MRSA and MSSA biofilm constructs had greater resistance to antimicrobials than corresponding two-dimensional (2D) cultures. Thicker 3D E.coli biofilms had greater resistance to tetracycline than thinner constructs over 7 days of treatment. Raman spectroscopy was also adapted in a novel approach to non-invasively diagnose 3D bioprinted biofilm constructs located within a joint replacement model. In conclusion, mature bacterial biofilm constructs were reproducibly 3D bioprinted for the first time using clinically relevant bacteria. This methodology allows the study of antimicrobial biofilm penetration in 3D, and potentially aids future antimicrobial research, replicating joint infection more closely than current 2D culture models. Furthermore, by deploying Raman spectroscopy in a novel fashion, it was possible to diagnose 3D bioprinted biofilm infections within a joint replacement model

Objectives. The purpose of this study was to refine an accepted contaminated rat femur defect model to result in an infection rate of approximately 50%. This threshold will allow examination of treatments aimed at reducing infection in open fractures with less risk of type II error. Methods . Defects were created in the stablised femurs of anaethetised rats, contaminated with Staphylococcus aureus and then debrided and irrigated six hours later. After 14 days, the bone and implants were harvested for separate microbiological analysis. This basic model was developed in several studies by varying the quantity of bacterial inoculation, introducing various doses of systemic antibiotics with and without local antibiotics. Results . The bacterial inoculation associated with a 50% infection rate was established as 1 × 10. 2. colony forming units (CFU). With an initial bacterial inoculum of 1 × 10. 5. CFU, the dose of systemic antibiotics associated with 50% infection was 5 mg/Kg of cafazolin injected sub-cutaneously every 12 hours, starting at the time of the first debridment and continuing for 72 hours (seven doses). The systemic dose of cafazolin was lowered to 2 mg/Kg when antibiotic polymethyl methacrylate beads were used concurrently with the same amount of bacterial inoculation. Conclusion. This model of open fracture infection has been further refined with potential for local and systemic antibiotics. This is a versatile model and with the concepts presented herein, it can be modified to evaluate various emerging therapies and concepts for open fractures. Cite this article: Bone Joint Res 2014;3:187–92