Prevention of deep infection in joint replacement surgery

Preclosure povidone-iodine lavage in total hip replacement surgery: Infection outcomes and cost-benefit analysis

OBJECTIVE

To report the outcomes and cost-benefit analysis of preclosure povidone-iodine lavage (PrePIL) used to reduce the risk of infection following total hip replacement (THR) surgery.

STUDY DESIGN

Retrospective study.

ANIMALS

One thousand six hundred ninety-nine dogs, 17 cats.

METHODS

The medical records of 2213 consecutive THR cases were reviewed to determine the incidence of infection. The last 102 were treated with PrePIL using a commercially sourced 0.035% povidone-iodine solution. Postoperative infection rates were compared. A cost-benefit analysis was used to calculate if a PrePIL protocol is economically feasible.

RESULTS

Twenty-one THRs out of 2111 (0.99%) that did not have PrePIL developed infection. Infection occurred in none of the 102 PrePIL cases. Cost analysis revealed a PrePIL break-even cost at $49.74 and a break-even infection rate of 0.949%. No complications were identified related to the use of PrePIL.

CONCLUSION

Preclosure povidone-iodine lavage appeared to be efficacious in lowering THR infection rates, and it appeared to be safe for this use based on our 102 consecutive cases. The cost of the PrePIL was minimal compared to the overall cost to resolve THR infection and the potential effect on hip function prognosis. The math formulas developed can be used by surgeons to calculate cost effectiveness and break-even cost based on their THR infection rate, and to compare to the cost of a THR revision and infection resolution.

CLINICAL SIGNIFICANCE

At current costs, PrePIL can be used in 2415 THR cases at a similar cost of a single revision surgery and resolution of a periprosthetic infection.

Failure analysis of articulating polymethyl methacrylate spacers in two-stage revision total hip arthroplasty

Aims

Two-stage exchange revision total hip arthroplasty (THA) performed in case of periprosthetic joint infection (PJI) has been considered for many years as being the gold standard for the treatment of chronic infection. However, over the past decade, there have been concerns about its safety and its effectiveness. The purposes of our study were to investigate our practice, collecting the overall spacer complications, and then to analyze their risk factors.

Methods

We retrospectively included 125 patients with chronic hip PJI who underwent a staged THA revision performed between January 2013 and December 2019. All spacer complications were systematically collected, and risk factors were analyzed. Statistical evaluations were performed using the Student's t-test, Mann-Whitney U test, and Fisher's exact test.

Results

Our staged exchange practice shows poor results, which means a 42% mechanical spacer failure rate, and a 20% recurrent infection rate over the two years average follow-up period. Moreover, we found a high rate of spacer dislocation (23%) and a low rate of spacer fracture (8%) compared to the previous literature. Our findings stress that the majority of spacer complications and failures is reflecting a population with high comorbid burden, highlighted by the American Society of Anesthesiology grade, Charlson Comorbidity Index, and Lee score associations, as well as the cardiac, pulmonary, kidney, or hepatic chronic conditions.

Conclusion

Our experience of a two-stage hip exchange revision noted important complication rates associated with high failure rates of polymethylmethacrylate spacers. These findings must be interpreted in the light of the patient’s comorbidity profiles, as the elective population for staged exchange has an increasing comorbid burden leading to poor results. In order to provide better results for this specific population, our conclusion suggests that comparative strategy studies are required to improve our therapeutic indication.

Cite this article: Bone Jt Open 2022;3(6):485–494.

Antibiotics- and Heavy Metals-Based Titanium Alloy Surface Modifications for Local Prosthetic Joint Infections

Prosthetic joint infection (PJI) is the second most common cause of arthroplasty failure. Though infrequent, it is one of the most devastating complications since it is associated with great personal cost for the patient and a high economic burden for health systems. Due to the high number of patients that will eventually receive a prosthesis, PJI incidence is increasing exponentially. As these infections are provoked by microorganisms, mainly bacteria, and as such can develop a biofilm, which is in turn resistant to both antibiotics and the immune system, prevention is the ideal approach. However, conventional preventative strategies seem to have reached their limit. Novel prevention strategies fall within two broad categories: (1) antibiotic- and (2) heavy metal-based surface modifications of titanium alloy prostheses. This review examines research on the most relevant titanium alloy surface modifications that use antibiotics to locally prevent primary PJI.

Socioeconomic Status May Not Be a Risk Factor for Periprosthetic Joint Infection

BACKGROUND

Periprosthetic joint infection (PJI) is a devastating complication after total joint arthroplasty, carrying significant economic and personal burden. The goal of this study is to use an established database to analyze socioeconomic variables and assess their relationship to PJI. Additionally, we sought to evaluate whether socioeconomic factors, along with other known risk factors of PJI, when controlled for in a statistical model affected the familial risk of PJI.

METHODS

With approval from our Institutional Review Board we performed a population-based retrospective cohort study on all primary total joint arthroplasty cases of the hip or knee (n = 85,332), within a statewide database, between January 1996 and December 2013. We excluded 9854 patients due to age <18 years, missing data, history of PJI prior to index procedure, and no evidence of 2-year follow-up (excluding those with PJI). Cases that developed PJI following the index procedure (n = 2282) were compared to those that did not (n = 73,196).

RESULTS

After adjusting for covariates, patients with Medicaid as a primary payer were at greater risk for experiencing PJI (relative risk 1.40, 95% confidence interval [CI] 1.08-1.82, P = .01). There was no difference in risk between the groups associated with education level or median household income (all, P > .05). First-degree relatives of patients who develop PJI (hazard ratio 1.66, 95% CI 1.23-2.24, P = .001) and first-degree and second-degree relatives combined (hazard ratio 1.39, 95% CI 1.09-1.77, P = .007) were at greater risk despite controlling for the above socioeconomic factors.

CONCLUSION

Our study provides further support that genetic factors may underlie PJI as we did observe significant familial risk even after accounting for socioeconomic factors and payer status. We did not find a correlation between education level or household income and PJI; however, Medicaid payees were at increased risk. Continued study is needed to define a possible heritable disposition to PJI in an effort to optimize treatment and possibly prevent this complication.

No differences in short-term outcomes between patients with anaerobic and aerobic culture positive prosthetic joint infection

BACKGROUND

Prosthetic joint infection (PJI) is a devastation complication of total joint arthroplasty that can result in poor patient outcomes. Anaerobic organisms make up a small proportion of PJI cases and are much less studied. Studies comparing patient outcomes in anaerobic PJI to outcomes in aerobic PJI are sparse. The purpose of this study was to compare the clinical presentation, duration of antibiotics, type of treatment provided, and final outcome between PJI patients with anaerobic infection and those with aerobic infection.

METHODS

This was a retrospective study of 26 patients who underwent treatment for PJI at a tertiary referral center. Eight patients with anaerobic PJI were compared to 18 patients with aerobic PJI in terms of clinical presentation, laboratory values, treatment duration, and functional outcome. Statistical analysis was performed on continuous variables of interest.

RESULTS

The results of our study showed that there are no differences in short term clinical outcomes between PJI patients with cultures positive for anaerobic vs aerobic organisms (38.9% vs 50% successfully treated). Inflammatory markers were higher in the aerobic group and patients in the anaerobic group tended to have fewer medical comorbidities.

CONCLUSION

PJI caused by anaerobic organisms results in poor patient outcomes similar to infection caused by aerobic organisms. There are some differences in clinical presentation between the two groups that can be explained by the fact that anaerobic organisms are of low virulence and result in indolent infections causing longstanding symptoms.

Strategies to Prevent Biofilm Infections on Biomaterials: Effect of Novel Naturally-Derived Biofilm Inhibitors on a Competitive Colonization Model of Titanium by Staphylococcus aureus and SaOS-2 Cells

Biofilm-mediated infection is a major cause of bone prosthesis failure. The lack of molecules able to act in biofilms has driven research aimed at identifying new anti-biofilm agents via chemical screens. However, to be able to accommodate a large number of compounds, the testing conditions of these screenings end up being typically far from the clinical scenario. In this study, we assess the potential applicability of three previously discovered anti-biofilm compounds to be part of implanted medical devices by testing them on in vitro systems that more closely resemble the clinical scenario. To that end, we used a competition model based on the co-culture of SaOS-2 mammalian cells and Staphylococcus aureus (collection and clinical strains) on a titanium surface, as well as titanium pre-conditioned with high serum protein concentration. Additionally, we studied whether these compounds enhance the previously proven protective effect of pre-incubating titanium with SaOS-2 cells. Out of the three, DHA1 was the one with the highest potential, showing a preventive effect on bacterial adherence in all tested conditions, making it the most promising agent for incorporation into bone implants. This study emphasizes and demonstrates the importance of using meaningful experimental models, where potential antimicrobials ought to be tested for the protection of biomaterials in translational applications.

A Comparison of Bacterial Adhesion and Biofilm Formation on Commonly Used Orthopaedic Metal Implant Materials: An In vitro Study

BACKGROUND

Bacterial adherence and biofilm formation on the surface of biomaterials can often lead to implant-related infections, which may vary depending on the species of microorganisms, type of biomaterial used, and physical characteristics of implant surfaces. However, there are limited studies specifically comparing biofilm formation between commonly used metallic orthopaedic implant materials and different bacterial strains. This in vitro study is to evaluate the ability of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa to adhere to and to form biofilms on the surface of five orthopaedic biomaterials, viz., cobalt and chromium, highly cross-linked polyethylene, stainless steel, trabecular metal, and titanium alloy.

MATERIALS AND METHODS

Bacterial adherence and bacterial biofilm-formation assays were performed by culturing S. aureus ATCC 29213, S. epidermidis ATCC 35984, E. coli ATCC 35218, K. pneumoniae ATCC 700603, and P. aeruginosa ATCC 27853 for 48 h on five different biomaterials. Quantitative bacterial adherence and biofilm formation were analyzed with a scanning electron microscope.

RESULTS

The highest level of adherence was observed on highly cross-linked polyethylene, followed by titanium, stainless steel, and trabecular metal, with the lowest occurring on the cobalt-chromium alloy. Among the bacterial strains tested, the ability for high adherence was observed with S. epidermidis and K. pneumoniae followed by P. aeruginosa and E. coli, whereas S. aureus showed the least adherence.

CONCLUSION

Cobalt-chromium was observed to have the lowest proclivity towards bacterial adherence compared to the other biomaterials tested. However, bacterial adhesion occurred with all the materials. Hence, it is necessary to further evaluate newer biomaterials that are resistant to bacterial adherence.

Laminar Air Flow Handling Systems in the Operating Room

BACKGROUND

Surgical site infection is associated with a substantial healthcare burden and remains one of the most challenging complications to treat. Airborne particles carrying contaminating micro-organisms are responsible for the majority of these infections.

METHODS

Various operating theater ventilatory systems have been developed to prevent direct airborne bacterial inoculation of the surgical wound. Laminar air flow uses positive pressure air currents through filtration units to direct air streams away from the operative field in order to create an ultraclean zone around the operative site.

DISCUSSION

Early studies reported lower infection rates with laminar air flow and therefore it became the accepted standard for implant-related surgery. However, more recent evidence has questioned its clinical importance. The purpose of this article is to review contemporary laminar air flow handling systems and the current evidence behind their use.

Etiology of Above-knee Amputations in the United States: Is Periprosthetic Joint Infection an Emerging Cause?

BACKGROUND

Above-knee amputation (AKA) is a morbid procedure and is performed for a number of conditions. Although AKA is usually performed for dysvascular disease, trauma, and malignancy, AKA is also considered in patients who have failed multiple salvage attempts at treating periprosthetic joint infection (PJI) of TKA. Although aggressive measures are being taken to treat PJI, the huge volume of TKAs might result in a large number of AKAs being performed for PJI in the United States. However, the national trends in the incidence of AKAs from different etiologies and the relative contribution of different etiologies to AKA are yet to be studied.

QUESTIONS/PURPOSES

(1) What are the temporal trends in the incidence of AKAs (from all causes) in the US population from 1998 to 2013? (2) What are the temporal trends in the incidence of AKAs by etiology (dysvascular disease, trauma, malignancy, and PJI)? (3) What are the temporal trends in the relative contribution of different etiologies to AKA?

METHODS

Using the Nationwide Inpatient Sample (NIS) from 1998 to 2013, AKAs were identified using International Classification of Diseases, 9 Revision (ICD-9) procedure code 84.17. The NIS database is the largest all-payer database in the United States containing information on approximately 20% of all the hospital admissions in the country. As a result of its sampling design, it allows for estimation of procedural volumes at the national level. All AKAs were grouped into one of the following five etiologies in a sequential manner using ICD-9 diagnosis codes: malignancy, PJI, trauma, dysvascular disease (peripheral vascular disease, diabetic, or a combination), and others. All of the numbers were converted to national estimates using sampling weights provided by the NIS, and the national incidence of AKAs resulting from various etiologies was calculated using the US population as the denominator. Poisson and linear regression analyses were used to analyze the annual trends.

RESULTS

From 1998 to 2013, the incidence of AKAs decreased by 47% from 174 to 92 AKAs per 1 million adults (incidence rate ratio [IRR]; change in the number of AKAs per 1 million adults per year; 0.96; 95% confidence interval [CI], 0.96-0.96; p < 0.001). The incidence of AKAs resulting from PJI increased by 263% (IRR, 1.07; 95% CI, 1.06-1.07; p < 0.001). An increase was also observed for AKAs from malignancy (IRR, 1.01; 95% CI, 1.00-1.02; p = 0.007), although to a smaller extent. AKAs from dysvascular causes (IRR, 0.96; 95% CI, 0.95-0.96; p < 0.001) and other etiologies (IRR, 0.97; 95% CI, 0.96-0.97; p < 0.001) decreased. There was no change in the incidence of AKAs related to trauma (IRR, 1.00; 95% CI, 0.99-1.00; p = 0.088). The proportion of AKAs resulting from PJI increased by 589% from 1998 to 2013 (coefficient = 0.18; 95% CI, 0.15-0.22; p < 0.001). The proportion of AKAs resulting from dysvascular causes decreased (coefficient = 0.18; 95% CI, 0.15-0.22; p < 0.001), whereas that resulting from malignancy (coefficient = 0.04; 95% CI, 0.03-0.05; p < 0.001) and trauma (coefficient = 0.13; 95% CI, 0.09-0.18; p < 0.001) increased.

CONCLUSIONS

The incidence of AKAs has decreased in the United States. AKAs related to dysvascular disease and other etiologies such as trauma and malignancy have either substantially decreased or remained fairly constant, whereas that resulting from PJI more than tripled. Given the increased resource utilization associated with limb loss, the results of this study suggest that national efforts to reduce disability should prioritize PJI. Further studies are required to evaluate the risk factors for AKA from PJI and to formulate better strategies to manage PJI.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Arthroplasty implant registries over the past five decades: Development, current, and future impact

Local, regional, and national registries have played an important role in the development of hip and knee arthroplasty and the treatment of patients with various maladies of these joints. Four arthroplasty registries stand out as leading forces behind the drive to popularize the use of registries and pursue the concept of evidence based medicine. The Mayo registry, started by Mark Coventry, is recognized as the oldest continuing registry for arthroplasty. The Harris Registry at Massachusetts General Hospital, along with the Mayo Registry, has greatly contributed to the advancement of arthroplasty surgery and have served an important role of identifying poorly performing implants and techniques in the United States. The Swedish Knee Arthroplasty Registry is the oldest national registry dedicated to joint arthroplasty and along with the Swedish Hip Arthroplasty Registry have established the infrastructure, analysis and reporting mechanisms, and leadership that has enabled other countries to subsequently develop national registries around the world. As more countries have adopted the concept of national registries, a new area of research is possible by pooling the resources of large registries as is now occurring with the Nordic countries. Several international organizations have been formed to promote future collaboration and develop international standards. The process of globalization of registries is a result of continued efforts over the past 50 years in improving and disseminating the knowledge gained from the early registries. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2319-2330, 2018.

Fluid collection bags pose a threat for bacterial contamination in primary total hip arthroplasty: a prospective, internally controlled, non-blinded trial

INTRODUCTION

Surgical equipment, and especially the so-called 'splash basins' that are used intraoperatively, are a potential source of bacterial contamination in primary total hip arthroplasty (THA). With this risk in mind, many commercially available draping kits include plastic bags that can be used to collect fluid or to temporarily store instruments. Following this rationale, we hypothesised that first: the fluid collection bags are a potential reservoir of bacteria and second: there is a time dependency for bacterial contamination.

MATERIALS AND METHODS

After ethics approval, we investigated in a prospective, internally controlled, non-blinded trial 43 patients who received primary THA. At the beginning of the surgery, we took deep, representative, intracapsular tissue samples, which served as negative controls. At the end of surgery, tissue samples were taken from the bottom of the 'fluid collection bag' for microbiological analysis.

RESULTS

All 86 control samples were negative. Out of the samples taken from the bags, a pathogen could be detected in four patients (9.3%). All pathogens were detected after a surgery time lasting longer than 90 min.

CONCLUSION

We were able to show that fluid collection bags are a potential reservoir for bacteria in THA when surgery time was greater than a 90-min threshold. Our data suggest that the risks from fluid collection bags outweigh the advantages of using them. Therefore, we recommend against the use of fluid collection bags intraoperatively in primary THA.

Reducing Hypotension and Acute Kidney Injury in the Elective Total Joint Arthroplasty Population: A Multi-Disciplinary Approach

BACKGROUND

When critically analyzing our hospital system's rate of hypotension and acute kidney injury (AKI) after total joint arthroplasty, our incidence rates (14.54%, 6.02%) were much higher than our peers (7.17%, 2.03%) and national rates (2.0%, 3.3%). We present a multi-disciplinary management intervention that aimed to decrease overall complication rates.

METHOD

A multi-disciplinary team implemented a protocol at our suburban hospital to limit complication rates after joint replacement surgery. Hypotension, AKI, length of stay (LOS), re-admission rates, and mortality rates were compared before the protocol was implemented, after protocol implementation, and after protocol integration into our EMR (electronic medical record).

RESULTS

In total, 1233 patients over 36 months were followed. Hypotension rates after protocol implementation into EMR (group 3) were significantly lower than rates before the protocol (group 1) (P = .002), with rates after protocol implementation without EMR (group 2) trending toward a significant decrease from group 1 (P = .064). AKI rates in group 3 were significantly lower than group 1 (P = .000) and group 2 (P = .006). No difference was seen in hypotension rates between group 2 and 3 (P = .792) or AKI rates between group 1 and 2 (P = .533). Finally, no significant difference was seen between groups in LOS (P = .560), re-admission rates (P = .378), and mortality rates (all 0.0%).

CONCLUSION

By implementing a comprehensive electronic protocol consisting of pre-operative risk stratification, multi-disciplinary medical optimization, and an evolving post-operative management plan, significant decreases in hypotension and AKI can be seen.

Outcomes and early revision rate after medial unicompartmental knee arthroplasty: prospective results from a non-designer single surgeon

Background

This prospective study evaluates outcomes and reoperation rates for unicompartmental knee arthroplasty (UKA) from a single non-designer surgeon using relatively extended criteria of degenerative changes of grade 2 or above in either or both non-operated compartments.

Methods

187 consecutive medial mobile bearing UKA implants were included after history, clinical assessment and radiological evaluation. 91 patients had extended clinical outcomes. Post-operative assessment included functional scoring with the Oxford Knee Score (OKS) and radiographic review. Survivorship curves were constructed using the life-table method, with 95% confidence intervals calculated using Rothman’s equation. Separate endpoints were examined: revision for any reason and revision for confirmed loosening.

Results

The mean follow-up was 3.5 years. The pre-operative OKS improved from a mean of 21.2 to 38.9 (Mann-Whitney U Test, p = < 0.001). Twelve Patients required further operations including 9 revisions. No patients developed deep infection and no surviving implants were loose radiographically. Survivorship at 7 years with endpoints of re-operation, revision and aseptic loosening at surgery or radiographically was 88.4% (95% CI 79.6–93.7), 93.1% (95% CI 85.5–96.9) and 97.3% (95% CI 91.2–99.2) respectively. The presence of pre-operative mild contralateral tibiofemoral or any extent of patellofemoral joint degeneration was of no consequence.

Discussion

The indications for UKA are being expanded to include patients with greater deformity, more advanced disease in the patellofemoral joint and even certain features in the lateral compartment indicative of an anteromedial pattern of osteoarthritis (OA). However, much of the supporting literature remains available only from designer centres. This study represents a group of patients with what we believe to be wider indications, along with decisions to treat made on clinical grounds and radiographs alone.

Conclusion

This study shows comparable clinical outcomes of UKA for extended indications from a high volume, high-usage non-designer unit.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-2099-2) contains supplementary material, which is available to authorized users.

Familial Clustering Identified in Periprosthetic Joint Infection Following Primary Total Joint Arthroplasty: A Population-Based Cohort Study

BACKGROUND

It is estimated that the cost to treat periprosthetic joint infection in the United States will approach $1.62 billion by 2020. Thus, the need to better understand the pathogenesis of periprosthetic joint infection is evident. We performed a population-based, retrospective cohort study to determine if familial clustering of periprosthetic joint infection was observed.

METHODS

Analyses were conducted using software developed at the Utah Population Database (UPDB) in conjunction with the software package R. The cohort was obtained by querying the UPDB for all patients undergoing total joint arthroplasty and for those patients who had subsequent periprosthetic joint infection. The magnitude of familial risk was estimated by hazard ratios (HRs) from Cox regression models to assess the relative risk of periprosthetic joint infection in relatives and spouses. Using percentiles for age strata, we adjusted for sex, body mass index (BMI) of ≥30 kg/m, and a history of smoking, diabetes, and/or end-stage renal disease. Additionally, we identified families with excess clustering of periprosthetic joint infection above that expected in the population using the familial standardized incidence ratio.

RESULTS

A total of 66,985 patients underwent total joint arthroplasty and 1,530 patients (2.3%) had a periprosthetic joint infection. The risk of periprosthetic joint infection following total joint arthroplasty was elevated in first-degree relatives (HR, 2.16 [95% confidence interval (CI), 1.29 to 3.59]) and combined first and second-degree relatives (HR, 1.79 [95% CI, 1.22 to 2.62]). Further, 116 high-risk pedigrees with a familial standardized incidence ratio of >2 and a p value of <0.05 were identified and 9 were selected for genotyping studies based on the observed periprosthetic joint infection/total joint arthroplasty ratio and visual inspection of the pedigrees for lack of excessive comorbidities.

CONCLUSIONS

Although preliminary, these data may help to guide further genetic research associated with periprosthetic joint infections. An understanding of familial risks could lead to new discoveries in creating patient-centered pathways for infection prevention in patients at risk.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Fast-resorbable antibiotic-loaded hydrogel coating to reduce post-surgical infection after internal osteosynthesis: a multicenter randomized controlled trial

BACKGROUND

Infection is one of the main reasons for failure of orthopedic implants. Antibacterial coatings may prevent bacterial adhesion and biofilm formation, according to various preclinical studies. The aim of the present study is to report the first clinical trial on an antibiotic-loaded fast-resorbable hydrogel coating (Defensive Antibacterial Coating, DAC®) to prevent surgical site infection, in patients undergoing internal osteosynthesis for closed fractures.

MATERIALS AND METHODS

In this multicenter randomized controlled prospective study, a total of 256 patients in five European orthopedic centers who were scheduled to receive osteosynthesis for a closed fracture, were randomly assigned to receive antibiotic-loaded DAC or to a control group (without coating). Pre- and postoperative assessment of laboratory tests, wound healing, clinical scores and X-rays were performed at fixed time intervals.

RESULTS

Overall, 253 patients were available with a mean follow-up of 18.1 ± 4.5 months (range 12-30). On average, wound healing, clinical scores, laboratory tests and radiographic findings did not show any significant difference between the two groups. Six surgical site infections (4.6%) were observed in the control group compared to none in the treated group (P < 0.03). No local or systemic side-effects related to the DAC hydrogel product were observed and no detectable interference with bone healing was noted.

CONCLUSIONS

The use of a fast-resorbable antibiotic-loaded hydrogel implant coating provides a reduced rate of post-surgical site infections after internal osteosynthesis for closed fractures, without any detectable adverse event or side-effects.

LEVEL OF EVIDENCE

2.

Fast corroding, thin magnesium coating displays antibacterial effects and low cytotoxicity

Bacterial colonisation and biofilm formation are characteristics of implant-associated infections. In search of candidates for improved prosthetic materials, fast corroding Mg-based coatings on titanium surfaces were examined for their cytotoxic and antimicrobial properties. Human osteoblasts and Staphylococcus epidermidis were each cultured on cylindrical Ti samples coated with a thin layer of Mg/Mg₄₅Zn₅Ca, applied via magnetron sputtering. Uncoated titanium samples served as controls. S. epidermidis was quantified by counting colony forming units. The biofilm-bound fraction was isolated via ultrasonic treatment, and the planktonic fraction via centrifugation. Biofilm-bound S. epidermidis was significantly decreased by approximately four to five orders of magnitude in both Mg- and Mg₄₅Zn₅Ca-coated samples after seven days compared to the control. The osteoblast viability was within the tolerance threshold of 70% stated in DIN EN ISO 10993-5:2009-10 for Mg (~80%) but not for Mg₄₅Zn₅Ca (~25%). Accordingly, Mg-coated titanium was identified as a promising candidate for an implant material with antibacterial properties and low cytotoxicity levels. The approach of exploiting fast corrosion contrasts with existing methods, which have generally focused on reducing corrosion.

The use of high-dose dual-impregnated antibiotic-laden cement with hemiarthroplasty for the treatment of a fracture of the hip: The Fractured Hip Infection trial

Aims

A fracture of the hip is the most common serious orthopaedic injury, and surgical site infection (SSI) is one of the most significant complications, resulting in increased mortality, prolonged hospital stay and often the need for further surgery. Our aim was to determine whether high dose dual antibiotic impregnated bone cement decreases the rate of infection.

Patients and Methods

A quasi-randomised study of 848 patients with an intracapsular fracture of the hip was conducted in one large teaching hospital on two sites. All were treated with a hemiarthroplasty. A total of 448 patients received low dose single-antibiotic impregnated cement (control group) and 400 patients received high dose dual-antibiotic impregnated cement (intervention group). The primary outcome measure was deep SSI at one year after surgery.

Results

The rate of deep SSI was 3.5% in the control group and 1.1% in the intervention group (p = 0.041; logistic regression adjusting for age and gender). The overall rate of non-infective surgical complications did not differ between the two groups (unadjusted chi-squared test; p > 0.999).

Conclusion

The use of high dose dual-antibiotic impregnated cement in these patients significantly reduces the rate of SSI compared with standard low dose single antibiotic loaded bone cement.

Cite this article: Bone Joint J 2016;98-B:1534–1541.

Use of Chlorhexidine Preparations in Total Joint Arthroplasty

Prosthetic joint infection (PJI) is a serious complication after total joint arthroplasty (TJA). Chlorhexidine is a widely used antiseptic because of its rapid and persistent action. It is well tolerated and available in different formulations at various concentrations. Chlorhexidine can be used for pre-operative skin cleansing, surgical site preparation, hand antisepsis of the surgical team and intra-articular irrigation of infected joints. The optimal intra-articular concentration of chlorhexidine gluconate in irrigation solution is 2%, to provide a persistent decrease in biofilm formation, though cytotoxicity might be an issue. Although chlorhexidine is relatively cheap, routine use of chlorhexidine without evidence of clear benefits can lead to unnecessary costs, adverse effects and even emergence of resistance. This review focuses on the current applications of various chlorhexidine formulations in TJA. As the treatment of PJI is challenging and expensive, effective preparations of chlorhexidine could help in the prevention and control of PJI.

Evaluation of calcium dihydroxide- and silver-coated implants in the rat tibia

BACKGROUND

Silver ions (Ag+) have strong antibacterial effects, and silver-coated materials are in widespread clinical use. However, the application of silver-coated medical devices is not without concerns: its use with direct bone contact is not established, and systemic toxic side effects of released Ag+ have been described. Therefore, alternative bactericidal coatings with a more localized way of acting - e.g., calcium dihydroxide, Ca(OH)2 (CH) - would be advantageous.

METHODS

A new rat model of the animal's tibial metaphysis was developed. In the left proximal tibiae of 36 male Wistar rats, titanium screws were implanted. The screws were coated with hydroxyapatite (HA; 12 animals: group I), low-dosed HA silver (HA-Ag; 12 animals: group II) and CH (12 animals: group III). After 6 weeks, all rats were sacrificed. The implants were evaluated for morphological changes on their surfaces, by light microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy; for osteointegration, by measurement of resistance to removal; and for bacterial colonization, by quantitative culture analysis. Additionally, the tibial bone was investigated histologically for signs of osteomyelitis and sonicated to detect bacterial loads.

RESULTS

(i) No microbiological or histological signs of infection could be determined on any of the screws or the surrounding bone. (ii) The bone-implant interface analysis revealed extensive bone formation and direct bone-implant contact on all HA, HA-Ag and HA-CH coated screws. (iii) HA and HA-Ag were partially, and CH was fully, degraded on the screw coating, allowing host bone to osteointegrate.

Alteration of inflammatory cytokine production in primary total knee arthroplasty using antibiotic-loaded bone cement

Background

The aim was to compare serum levels of interleukin-6 (SIL6), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and joint fluid IL-6 (JIL-6) level between total knee arthroplasty (TKA) that used bone cement (BC group) and antibiotic-loaded bone cement (ALBC group).

Materials and methods

Thirty-nine patients (40 TKAs) with a mean age of 69.6 years were non-randomly assigned to the BC or ALBC groups. Samples of SIL6, ESR, and CRP were collected at baseline and at 24 h, 72 h, and 4 weeks after surgery. JIL-6 levels were collected intraoperatively before joint arthrotomy, before finishing the procedure and 24 h after surgery. Postoperative mediator levels were compared with baseline levels within the same group and between groups at each time point. Knee Society Score-knee (KSSK) and Knee Society Score-function (KSSF) scores were evaluated.

Results

SIL-6, ESR, and CRP levels were significantly elevated at 24 and 72 h, compared to baseline. Only SIL-6 levels at 72 h in the ALBC group showed a significantly lower level than those in the BC group. JIL-6 levels were not different between groups. There were no significant differences in KSSK or KSSF scores between groups at 4 weeks and the most recent follow-up (1.4 ± 0.6 years) evaluation. No correlations were identified among SIL-6 and JIL-6 levels at 24 and 72 h, and KSSK and KSSF scores at 4 weeks and at the most recent evaluation.

Conclusions

ALBC showed a favorable immunomodulatory effect and lower SIL-6 level at 72 h following TKA compared to BC, although functional benefits require further investigation.

Level of evidence

OCEBM, Level 3.

Calcium-Based, Antibiotic-Loaded Bone Substitute as an Implant Coating: A Pilot Clinical Study

Background: Implant-related infections remain a major complication after orthopaedic surgery. Antibacterial coating of implants may prevent bacterial adhesion and biofilm formation. However, in spite of extensive preclinical research in the field, antibacterial coatings to protect orthopaedic implants in the clinical setting remain particularly few. The aim of the present study is to evaluate the safety of a calcium-based, antibiotic-loaded bone substitute as an antibacterial coating of cementless joint prosthesis. Methods: From March 2013 to August 2015, 20 consecutive patients scheduled for cementless or hybrid two-stage revision surgery for peri-prosthetic joint infection were included in this prospective, observational, pilot study. Cerament G or Cerament V, a gentamicin or vancomycin-loaded calcium-based resorbable bone substitute (60% calcium sulphate, 40% hydroxyapatite), was applied at surgery on the stem surface of hip (n=7) or knee (n=13) revision prosthesis. After surgery, all patients underwent clinical (HHS or KSS and SF-12 score), laboratory and radiographic evaluation at 3, 6 and 12 months and yearly thereafter. Results: At a minimum of 12 months follow-up, 19/20 (95%) patients showed no recurrence of infection and no signs of radiographic loosening of the stem. No adverse events were associated with the use of Cerament G or V. Conclusions: This is the first pilot clinical study on the short-term safety of using a calcium-based, gentamicin or vancomycin-loaded bone substitute as a surface coating on cementless prosthetic implants. If confirmed by larger studies and at longer follow-ups, these findings may open a new prospective to protect intra-operatively orthopedic implants from bacterial adhesion, through the use of resorbable, osteoconductive, antibiotic carriers.

Pharmacokinetics of gentamicin eluted from a regenerating bone graft substitute: In vitro and clinical release studies

Objectives

Deep bone and joint infections (DBJI) are directly intertwined with health, demographic change towards an elderly population, and wellbeing.

The elderly human population is more prone to acquire infections, and the consequences such as pain, reduced quality of life, morbidity, absence from work and premature retirement due to disability place significant burdens on already strained healthcare systems and societal budgets.

DBJIs are less responsive to systemic antibiotics because of poor vascular perfusion in necrotic bone, large bone defects and persistent biofilm-based infection. Emerging bacterial resistance poses a major threat and new innovative treatment modalities are urgently needed to curb its current trajectory.

Materials and Methods

We present a new biphasic ceramic bone substitute consisting of hydroxyapatite and calcium sulphate for local antibiotic delivery in combination with bone regeneration. Gentamicin release was measured in four setups: 1) in vitro elution in Ringer’s solution; 2) local elution in patients treated for trochanteric hip fractures or uncemented hip revisions; 3) local elution in patients treated with a bone tumour resection; and 4) local elution in patients treated surgically for chronic corticomedullary osteomyelitis.

Results

The release pattern in vitro was comparable with the obtained release in the patient studies. No recurrence was detected in the osteomyelitis group at latest follow-up (minimum 1.5 years).

Conclusions

This new biphasic bone substitute containing antibiotics provides safe prevention of bone infections in a range of clinical situations. The in vitro test method predicts the in vivo performance and makes it a reliable tool in the development of future antibiotic-eluting bone-regenerating materials.

Cite this article: M. Stravinskas, P. Horstmann, J. Ferguson, W. Hettwer, M. Nilsson, S. Tarasevicius, M. M. Petersen, M. A. McNally, L. Lidgren. Pharmacokinetics of gentamicin eluted from a regenerating bone graft substitute: In vitro and clinical release studies. Bone Joint Res 2016;5:427–435. DOI: 10.1302/2046-3758.59.BJR-2016-0108.R1.

Does an Antibiotic-Loaded Hydrogel Coating Reduce Early Post-Surgical Infection After Joint Arthroplasty?

Background: Infection remains among the main reasons for joint prosthesis failure. Preclinical reports have suggested that antibacterial coatings of implants may prevent bacterial adhesion and biofilm formation. This study presents the results of the first clinical trial on an antibiotic-loaded fast-resorbable hydrogel coating (Defensive Antibacterial Coating, DAC^®) in patients undergoing hip or knee prosthesis. Methods: In this multicenter, randomized prospective study, a total of 380 patients, scheduled to undergo primary (n=270) or revision (n=110) total hip (N=298) or knee (N=82) joint replacement with a cementless or a hybrid implant, were randomly assigned, in six European orthopedic centers, to receive an implant either with the antibiotic-loaded DAC coating (treatment group) or without coating (control group). Pre- and postoperative assessment of clinical scores, wound healing, laboratory tests, and x-ray exams were performed at fixed time intervals. Results: Overall, 373 patients were available at a mean follow-up of 14.5 ± 5.5 months (range 6 to 24). On average, wound healing, laboratory and radiographic findings showed no significant difference between the two groups. Eleven early surgical site infections were observed in the control group and only one in the treatment group (6% vs. 0.6%; p=0.003). No local or systemic side effects related to the DAC hydrogel coating were observed, and no detectable interference with implant osteointegration was noted. Conclusions: The use of a fast-resorbable, antibiotic-loaded hydrogel implant coating can reduce the rate of early surgical site infections, without any detectable adverse events or side effects after hip or knee joint replacement with a cementless or hybrid implant.

Reducing periprosthetic joint infection: what really counts?

Periprosthetic joint infection (PJI) remains one of the most challenging complications after joint arthroplasty. Despite improvements in surgical techniques and in the use of antibiotic prophylaxis, it remains a major cause of implant failure and need for revision. PJI is associated with both human host-related and bacterial agent-related factors that can interact in all the phases of the procedure (preoperative, intraoperative and postoperative). Prevention is the first strategy to implement in order to minimize this catastrophic complication. The present review focuses on the preoperative period, and on what to do once risk factors are fully understood and have been identified.

Covalent immobilization of antimicrobial agents on titanium prevents Staphylococcus aureus and Candida albicans colonization and biofilm formation

OBJECTIVES

Biofilm-associated implant infections represent a serious public health problem. Covalent immobilization of antimicrobial agents on titanium (Ti), thereby inhibiting biofilm formation of microbial pathogens, is a solution to this problem.

METHODS

Vancomycin (VAN) and caspofungin (CAS) were covalently bound on Ti substrates using an improved processing technique adapted to large-scale coating of implants. Resistance of the VAN-coated Ti (VAN-Ti) and CAS-coated Ti (CAS-Ti) substrates against in vitro biofilm formation of the bacterium Staphylococcus aureus and the fungal pathogen Candida albicans was determined by plate counting and visualized by confocal laser scanning microscopy. The efficacy of the coated Ti substrates was also tested in vivo using an adapted biomaterial-associated murine infection model in which control-Ti, VAN-Ti or CAS-Ti substrates were implanted subcutaneously and subsequently challenged with the respective pathogens. The osseointegration potential of VAN-Ti and CAS-Ti was examined in vitro using human bone marrow-derived stromal cells, and for VAN-Ti also in a rat osseointegration model.

RESULTS

In vitro biofilm formation of S. aureus and C. albicans on VAN-Ti and CAS-Ti substrates, respectively, was significantly reduced compared with biofilm formation on control-Ti. In vivo, we observed over 99.9% reduction in biofilm formation of S. aureus on VAN-Ti substrates and 89% reduction in biofilm formation of C. albicans on CAS-Ti substrates, compared with control-Ti substrates. The coated substrates supported osseointegration in vitro and in vivo.

CONCLUSIONS

These data demonstrate the clinical potential of covalently bound VAN and CAS on Ti to reduce microbial biofilm formation without jeopardizing osseointegration.

Risk Factors for Infection Following Total Knee Arthroplasty: A Series of 3836 Cases from One Institution

Higher PJI rates may be related to identifiable risk factors, which may or may not be modifiable. Identifying risk factors preoperatively provides opportunities for modification and potentially decreasing the incidence of PJI. The purposes of this study were to: (1) retrospectively identify and quantify risk factors for PJI following primary TKA, and (2) to classify those significant risk factors as either non-modifiable or modifiable for intervention prior to surgery. Optimization of modifiable risk factors such as Staphylococcus aureus colonization, and tobacco use prior to primary TKA may decrease the incidence of periprosthetic joint infection after primary TKA, thereby reducing morbidity and the costs associated with treating those infections.

Antibacterial efficacy of titanium-containing alloy with silver-nanoparticles enriched diamond-like carbon coatings

Silver ions (Ag⁺) have strong bactericidal effects and Ag-coated medical devices proved their effectiveness in reducing infections in revision total joint arthroplasty. We quantitatively determined the antimicrobial potency of different surface treatments on a titanium alloy (Ti), which had been conversed to diamond-like carbon (DLC-Ti) and doped with high (Ag:PVP = 1:2) and low (Ag:PVP = 1:10 and 1:20) concentrations of Ag (Ag-DLC-Ti) with a modified technique of ion implantation. Bacterial adhesion and planktonic growth of clinically relevant bacterial strains (Staphylococcus epidermidis,Staphylococcus aureus, and Pseudomonas aeruginosa) on Ag-DLC-Ti were compared to untreated Ti by quantification of colony forming units on the adherent surface and in the growth medium as well as semiquantitatively by determining the grade of biofilm formation by scanning electron microscopy. (1) A significant (p < 0.05) antimicrobial effect could be found for all Ag-DLC-Ti samples (reduced growth by 5.6–2.5 logarithmic levels). (2) The antimicrobial effect was depending on the tested bacterial strain (most for P. aeruginosa, least for S. aureus). (3) Antimicrobial potency was positively correlated with Ag concentrations. (4) Biofilm formation was decreased by Ag-DLC-Ti surfaces. This study revealed potent antibacterial effects of Ag-DLC-Ti. This may serve as a promising novel approach to close the gap in antimicrobial protection of musculoskeletal implants.

Antibacterial coating of implants in orthopaedics and trauma: a classification proposal in an evolving panorama

Implanted biomaterials play a key role in current success of orthopedic and trauma surgery. However, implant-related infections remain among the leading reasons for failure with high economical and social associated costs. According to the current knowledge, probably the most critical pathogenic event in the development of implant-related infection is biofilm formation, which starts immediately after bacterial adhesion on an implant and effectively protects the microorganisms from the immune system and systemic antibiotics. A rationale, modern prevention of biomaterial-associated infections should then specifically focus on inhibition of both bacterial adhesion and biofilm formation. Nonetheless, currently available prophylactic measures, although partially effective in reducing surgical site infections, are not based on the pathogenesis of biofilm-related infections and unacceptable high rates of septic complications, especially in high-risk patients and procedures, are still reported.In the last decade, several studies have investigated the ability of implant surface modifications to minimize bacterial adhesion, inhibit biofilm formation, and provide effective bacterial killing to protect implanted biomaterials, even if there still is a great discrepancy between proposed and clinically implemented strategies and a lack of a common language to evaluate them.To move a step forward towards a more systematic approach in this promising but complicated field, here we provide a detailed overview and an original classification of the various technologies under study or already in the market. We may distinguish the following: 1. Passive surface finishing/modification (PSM): passive coatings that do not release bactericidal agents to the surrounding tissues, but are aimed at preventing or reducing bacterial adhesion through surface chemistry and/or structure modifications; 2. Active surface finishing/modification (ASM): active coatings that feature pharmacologically active pre-incorporated bactericidal agents; and 3. Local carriers or coatings (LCC): local antibacterial carriers or coatings, biodegradable or not, applied at the time of the surgical procedure, immediately prior or at the same time of the implant and around it. Classifying different technologies may be useful in order to better compare different solutions, to improve the design of validation tests and, hopefully, to improve and speed up the regulatory process in this rapidly evolving field.

Risk factors for perioperative hyperglycemia in primary hip and knee replacements

BACKGROUND AND PURPOSE

Perioperative hyperglycemia has been associated with adverse outcomes in several fields of surgery. In this observational study, we identified factors associated with an increased risk of hyperglycemia following hip and knee replacement.

PATIENTS AND METHODS

We prospectively monitored changes in glucose following primary hip and knee replacements in 191 patients with osteoarthritis. Possible associations of patient characteristics and operation-related factors with hyperglycemia (defined as glucose > 7.8 mmol/L in 2 consecutive measurements) and severe hyperglycemia (glucose > 10 mmol/L) were analyzed using binary logistic regression with adjustment for age, sex, operated joint, and anesthesiological risk score.

RESULTS

76 patients (40%) developed hyperglycemia, and 48 of them (25% of the whole cohort) had severe hyperglycemia. Glycemic responses were similar following hip replacement and knee replacement. Previously diagnosed diabetes was associated with an increased risk of hyperglycemia and severe hyperglycemia, compared to patients with normal glucose metabolism, whereas newly diagnosed diabetes and milder glucose metabolism disorders had no effect. In patients without previously diagnosed diabetes, increased values of preoperative glycosylated hemoglobin (HbA1c) and fasting glucose on the day of operation were associated with hyperglycemia. Higher anesthesiological risk score-but none of the operation-related factors analyzed-was associated with an increased risk of hyperglycemia.

INTERPRETATION

Perioperative hyperglycemia is common in primary hip and knee replacements. Previously diagnosed diabetes is the strongest risk factor for hyperglycemia. In patients with no history of diabetes, preoperative HbA1c and fasting glucose on the day of operation can be used to stratify the risk of hyperglycemia.

Genetic susceptibility to prosthetic joint infection following total joint arthroplasty: A systematic review

BACKGROUND

Prosthetic joint infection (PJI) is the most common cause of total joint arthroplasty failure and revision surgery. Genetic polymorphisms could be determinant factors for PJI.

METHODS

We performed a systematic research of Medline, Pubmed, Embase, Cochrane Library, and Google Scholar, and identified 11 studies with 34 kinds of gene polymorphisms, were included in the synthesis.

RESULTS

Our data suggest that the C allele and genotype C/C for MBL-550 SNP, genotype A/A for MBL-54 SNP and G allele for MBL-221 SNP increase the risk of PJI, while G allele and genotype G/G for MBL-550 SNP decrease the risk of PJI in Caucasian populations. Several other genes reported by single-center studies also contribute to the genetic susceptibility to septic PJI. No definitive conclusions could be achieved due to the small amount of data in the included studies.

CONCLUSION

Several genes contribute to the genetic susceptibility to PJI following total joint arthroplasty. Further studies will enhance the understanding of PJI, and may inform and direct early interventions.

The Otto Aufranc Award: Modifiable versus nonmodifiable risk factors for infection after hip arthroplasty

BACKGROUND

Periprosthetic joint infections (PJIs) are associated with increased morbidity and cost. It would be important to identify any modifiable patient- and surgical-related factors that could be modified before surgery to decrease the risk of PJI.

QUESTIONS/PURPOSES

We sought to identify and quantify the magnitude of modifiable risk factors for deep PJIs after primary hip arthroplasty.

METHODS

A series of 3672 primary and 406 revision hip arthroplasties performed at a single specialty hospital over a 3-year period were reviewed. All deep PJIs were identified using the Centers for Disease Control and Prevention case definitions (ie, occurs within 30-90 days postoperatively, involves deep soft tissues of the incision, purulent drainage, dehiscence and fever, localized pain or tenderness). Univariate and multivariate analyses determined the association between patient and surgical risk factors and PJIs. For the elective patients, the procedure was performed on the day of admission ("same-day procedure"), whereas for the fracture and nonelective patients, the procedure was performed 1 or more days postadmission ("nonsame-day procedure"). Staphylococcus aureus colonization, tobacco use, and body mass index (BMI) were defined as patient-related modifiable risk factors.

RESULTS

Forty-seven (1.3%) deep PJIs were identified. Infection developed in 20 of 363 hips of nonsame-day procedures and 27 of 3309 same-day procedures (p=0.006). There were eight (2%) infections in the revision group. After controlling for confounding variables, our multivariate analysis showed that BMI≧40 kg/m2 (odds ratio [OR], 4.13; 95% confidence interval [CI], 1.3-12.88; p=0.01), operating time>115 minutes (OR, 3.38; 95% CI, 1.23-9.28; p=0.018), nonsame-day surgery (OR, 4.16; 95% CI, 1.44-12.02; p=0.008), and revision surgery (OR, 4.23; 95% CI, 1.67-10.72; p<0.001) are significant risk factors for PJIs. Tobacco use and S aureus colonization were additive risk factors when combined with other significant risk factors (OR, 12.76; 95% CI, 2.47-66.16; p=0.017).

CONCLUSIONS

Nonsame-day hip and revision arthroplasties have higher infection rates than same-day primary surgeries. These characteristics are not modifiable and should be categorized as a separate cohort for complication-reporting purposes. Potentially modifiable risk factors in our patient population include operating time, elevated BMI, tobacco use, and S aureus colonization. Modifying risk factors may decrease the incidence of PJIs. When reporting deep PJI rates, stratification into preventable versus nonpreventable infections may provide a better assessment of performance on an institutional and individual surgeon level.

LEVEL OF EVIDENCE

Level IV, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Reinforcing good practice: Implementation of guidelines at hospital G. Pini

INTRODUCTION

Surgical site infections (SSIs) in orthopaedic surgery are a demanding complication for the patient and in terms of economics. Many guidelines (GLs) are available on antibiotic prophylaxis as an effective preventive measure; however, these GLs are often ignored in practice. A surveillance study of SSIs in arthroplasty, promoted by the Italian Study Group of Hospital Hygiene of the Italian Society of Public Health (SitI), showed a high percentage of non-adherence to GLs on antibiotic prophylaxis.

OBJECTIVES

The purpose of this study was to review the existing GLs, share them within the hospital and then monitor their implementation.

MATERIALS AND METHODS

Information and training are considered to be great tools for implementation and sharing of GLs, which leads to significant improvements in clinical practice. A multidisciplinary team comprising infectious disease specialists, orthopaedic surgeons, nurse epidemiologists and public health specialists was established at the G. Pini Hospital in Milan to revise GLs, and to organise educational events for their implementation, sharing and dissemination. A checklist was devised for monitoring purposes.

RESULTS

GLs were presented to orthopaedic surgeons and nurse coordinators during two educational events. Meetings were organised in each unit to present the results of the surveillance of SSIs in arthroplasty and to discuss the reasons why the prophylaxis regimens adopted were not consistent with GLs. It was emphasised that the most important issue, on which there is consensus in the scientific literature, was related to the duration of prophylaxis beyond 24h. The review process for GLs was presented and pocket-sized GLs were given to surgeons. The importance of documenting on medical record any deviations from the GLs was emphasised.

CONCLUSIONS

Any changes in behaviour in clinical practice must be monitored and evaluated regularly. The monitoring of GLs in terms of correct choice of drug, timing of administration and duration of prophylaxis is made using a special checklist on a representative sample of medical records.

Two-stage hip revision arthroplasty with a hexagonal modular cementless stem in cases of periprosthetic infection

Background

Two-stage revision arthroplasty is today regarded as the gold standard treatment method for deep prosthetic joint infection. The aim of the present study was to evaluate clinical and functional outcomes with the Modular Universal Tumor And Revision System (MUTARS) RS stem in patients undergoing two-stage revisions.

Methods

The functional and clinical outcomes for 43 patients who had undergone two-stage revision procedures for PJI were analyzed in a retrospective study. The minimum follow-up period was 24 months. Shorter follow-up periods were only observed when there were complications such as loosening or recurrent infection. The mean follow-up period was 3.86 years (range 7 months to 11.6 years).

Results

The success rate with infection control for PJI was 93%. Reinfection occurred in four cases (7%). The risk of reinfection after MRSA infection was 20.5 times greater (P >0.01) than with sensitive or unknown bacteria. Two aseptic loosening occurred after 7 and 20 months. The average Harris Hip Score was 80 (range 62–93).

Conclusion

This retrospective study showed a 93% rate of eradication using specific antibiotic therapy. With the modular MUTARS RS stem, there was a low rate of aseptic loosening of 4.6%. MRSA infection was identified as a risk factor for reinfection. The two-stage procedure with modular cementless implants used is therefore appropriate for treating periprosthetic infections associated with hip endoprostheses.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-398) contains supplementary material, which is available to authorized users.

Deep infection after total hip replacement: a method for national incidence surveillance

OBJECTIVE

The purpose of this study was to estimate the incidence of deep periprosthetic joint infections (PJIs) after primary total hip replacement (THR) in Sweden prior to the introduction of a national initiative to reduce these infections.

DESIGN

Prospective open cohort study with 2 years follow-up of each subject.

SETTING

All THR-performing clinics in Sweden.

METHODS

All patients registered for a primary THR in the Swedish Hip Arthroplasty Register between July 1, 2005, and December 31, 2008, were selected for the study (45,531 patients with 49,219 THRs) and were matched with the Swedish Prescribed Drug Register. All patients with a minimum of 4 weeks of continuous outpatient antibiotic treatment within 2 years after their primary THR (1,989 patients with 2,219 THRs) were selected for a medical records review, and the number of cases with PJI was determined.

RESULTS

The cumulative incidence of PJI within 2 years after primary THR was 0.9% (95% confidence interval, 0.85-1.02; n = 443), and 405 of these had been reoperated. The incidence rate of PJI for the first 3 months was 5 per 10,000 THR-weeks and, thereafter, 0.3 per 10,000 THR-weeks. Staphylococcus aureus and coagulase-negative staphylococci were the most common bacteria isolated.

CONCLUSIONS

This study describes a new method of national postoperative infection surveillance. The incidence is similar to previous smaller reports and is useful for monitoring changes over time to evaluate the national initiative to reduce infections.

The Swedish Knee Arthroplasty Register: a review

We are entering a new era with governmental bodies taking an increasingly guiding role, gaining control of registries, demanding direct access with release of open public information for quality comparisons between hospitals. This review is written by physicians and scientists who have worked with the Swedish Knee Arthroplasty Register (SKAR) periodically since it began. It reviews the history of the register and describes the methods used and lessons learned. Cite this article: Bone Joint Res 2014;3:217-22.

Does a mobile laminar airflow screen reduce bacterial contamination in the operating room? A numerical study using computational fluid dynamics technique

Background

Air-borne bacteria in the operating room (OR) may contaminate the surgical wound, either by direct sedimentation from the air or indirectly, by contaminated sterile instruments. Reduced air contamination can be achieved with an efficient ventilation system. The current study assesses the additive effect of a mobile laminar airflow (MLAF) unit on the microbiological air quality in an OR supplied with turbulent-mixing air ventilation.

Methods

A recently designed OR in NKS (Nya Karolinska Sjukhuset, Stockholm, Sweden) was the physical model for this study. Simulation was made with MLAF units adjacent to the operating table and the instrument tables, in addition to conventional turbulent-mixing ventilation. The evaluation used numerical calculation by computational fluid dynamics (CFD). Sedimentation rates (CFU/m²/h) were calculated above the operating table and two instrument tables, and in the periphery of the OR. Bacterial air contamination (CFU/m³) was simulated above the surgical and instrument tables with and without the MLAF unit.

Results

The counts of airborne and sedimenting, bacteria-carrying particles downstream of the surgical team were reduced to an acceptable level for orthopedic/implant surgery when the MLAF units were added to conventional OR ventilation. No significant differences in mean sedimentation rates were found in the periphery of the OR.

Conclusions

The MLAF screen unit can be a suitable option when the main OR ventilation system is unable to reduce the level of microbial contamination to an acceptable level for orthopedic implant surgery. However, MLAF effect is limited to an area within 1 m from the screen. Increasing air velocity from the MLAF above 0.4 m/s does not increase the impact area.

The risk of surgical site infection and re-admission in obese patients undergoing total joint replacement who lose weight before surgery and keep it off post-operatively

This study evaluated whether obese patients who lost weight before their total joint replacement and kept it off post-operatively were at lower risk of surgical site infection (SSI) and re-admission compared with those who remained the same weight.

We reviewed 444 patients who underwent a total hip replacement and 937 with a total knee replacement who lost weight pre-operatively and sustained their weight loss after surgery. After adjustments, patients who lost weight before a total hip replacement and kept it off post-operatively had a 3.77 (95% confidence interval (CI) 1.59 to 8.95) greater likelihood of deep SSIs and those who lost weight before a total knee replacement had a 1.63 (95% CI 1.16 to 2.28) greater likelihood of re-admission compared with the reference group.

These findings raise questions about the safety of weight management before total replacement of the hip and knee joints.

Cite this article: Bone Joint J 2014;96-B:629–35.

Impact of perioperative allogeneic and autologous blood transfusion on acute wound infection following total knee and total hip arthroplasty

BACKGROUND

Patients undergoing total hip or knee arthroplasty frequently receive blood transfusions. The relationship between transfusion and the risk of infection following total joint arthroplasty is unclear. In this study, we sought to examine the impact of allogeneic and autologous transfusion on the risk of acute infection following total hip and total knee arthroplasty.

METHODS

We performed a retrospective study of consecutive primary total knee arthroplasties and total hip arthroplasties. Patients who had a reoperation for suspected infection within three months after the arthroplasty were identified. Differences in risk factors were assessed across transfusion groups: no transfusion, autologous only, and allogeneic exposure (allogeneic with or without additional autologous transfusion). Backward-stepwise logistic regression analysis was used to compare reoperations (as outcomes) between cases with and those without allogeneic exposure. Prespecified covariates were body mass index, diabetes, an American Society of Anesthesiologists (ASA) score of >2, preoperative hematocrit, and total number of units transfused perioperatively.

RESULTS

We identified 3352 patients treated with a total hip or knee arthroplasty (1730 total knee arthroplasties and 1622 total hip arthroplasties) for inclusion in the study. Transfusion was given in 1746 cases: 836 of them had allogeneic exposure, and 910 had autologous-only transfusion. There were thirty-two reoperations (0.95%) for suspected infection. Between-group risk-factor differences were observed. The mean age and the rates of diabetes, immunosuppression, ASA scores of >2, and bilateral surgery were highest in the allogeneic group, as were estimated blood loss, surgery duration, and total number of units transfused (p < 0.001). In the unadjusted analyses, the rate of reoperations for suspected infection was higher in the cases with allogeneic exposure (1.67%) than in those without allogeneic exposure (0.72%) (p = 0.013). Autologous-only transfusion was not associated with a higher reoperation rate. However, multivariable logistic regression demonstrated that the total number of units transfused (p = 0.011) and an ASA score of >2 (p = 0.008)-but not allogeneic exposure-were significantly predictive of a reoperation.

CONCLUSIONS

Perioperative allogeneic transfusion was associated with a higher rate of reoperations for suspected acute infection. However, patients with allogeneic exposure had increased infection risk factors. After adjustment for the total number of units transfused and an ASA score of >2, allogeneic exposure was not significantly predictive of a reoperation for infection.

Prevention of surgical site infection in total joint arthroplasty: an international tertiary care center survey

BACKGROUND

Prevention strategies are critical to reduce infection rates in total joint arthroplasty (TJA), but evidence-based consensus guidelines on prevention of surgical site infection (SSI) remain heterogeneous and do not necessarily represent this particular patient population.

QUESTIONS/PURPOSES

What infection prevention measures are recommended by consensus evidence-based guidelines for prevention of periprosthetic joint infection? How do these recommendations compare to expert consensus on infection prevention strategies from orthopedic surgeons from the largest international tertiary referral centers for TJA?

PATIENTS AND METHODS

A review of consensus guidelines was undertaken as described by Merollini et al. Four clinical guidelines met inclusion criteria: Centers for Disease Control and Prevention's, British Orthopedic Association, National Institute of Clinical Excellence's, and National Health and Medical Research Council's (NHMRC). Twenty-eight recommendations from these guidelines were used to create an evidence-based survey of infection prevention strategies that was administered to 28 orthopedic surgeons from members of the International Society of Orthopedic Centers. The results between existing consensus guidelines and expert opinion were then compared.

RESULTS

Recommended strategies in the guidelines such as prophylactic antibiotics, preoperative skin preparation of patients and staff, and sterile surgical attire were considered critically or significantly important by the surveyed surgeons. Additional strategies such as ultraclean air/laminar flow, antibiotic cement, wound irrigation, and preoperative blood glucose control were also considered highly important by surveyed surgeons, but were not recommended or not uniformly addressed in existing guidelines on SSI prevention.

CONCLUSION

Current evidence-based guidelines are incomplete and evidence should be updated specifically to address patient needs undergoing TJA.

Two-stage arthroplasty for prosthetic joint infection: a systematic review of acute kidney injury, systemic toxicity and infection control

Periprosthetic infections of hip and knee joints are now treated by two-stage revision arthroplasty with an infection control rate of 91%. The present systematic review studied the reported incidence of acute kidney injury (AKI) and infection recurrence from January 1989 to June 2012 to assess the risk-benefit ratio of antibiotic spacer use. Ten observational studies (n=544 patients) with clinical outcomes showed an average incidence of AKI of 4.8%. The average reported persistence or recurrence rate of infection was 11% during a follow-up period that ranged from 13 to 108 months. The risk-benefit ratio presently favors treatment although there appears to be higher complication rates and incidence of AKI than previously reported. Marked heterogeneity in practice and lack of detail in reporting precluded more robust quantitative synthesis. Clinicians need to be aware of the potential risk of AKI, particularly in high-risk patients; practice patterns for the use of antibiotic spacers need to be standardized.

Clinical characteristics, microbiology, and outcomes of prosthetic joint infection in Taiwan

BACKGROUND

Prosthetic joint infection (PJI) after total knee or hip replacement is a devastating complication associated with substantial morbidity and economic cost. The incidence of prosthetic joint infection is increasing as the use of mechanical joint replacement increases. The treatment approach to prosthetic joint infection is based on different clinical situations such as a patient's comorbidities, epidemic microbiology data, and surgical procedures. The aim of our study was to understand clinical characteristics of prosthetic joint infection, the microbiology of the prosthetic joint infection, and the outcomes of different treatment strategies during 2006-2011.

METHODS

We retrospectively collected cases of prosthetic joint infection in the National Taiwan University Hospital between January 1, 2006 and December 31, 2011. The patients' characteristics, microbiology, outcomes, and factors associated with treatment success were recorded.

RESULTS

One hundred and forty-four patients were identified as having PJI. Of these, 92 patients were entered into per-protocol analysis. Staphylococcus aureus was the most common causative organism (29.9%), followed by coagulase-negative Staphylococci (16.7%), and Enterococci (9.7%). The overall treatment success rate was 50%. Patients who received a two-stage revision had a better outcome, compared to patients who underwent other types of surgeries (70% vs. 32.7%, respectively; p < 0.001). In multivariate analysis, the two-stage revision was significantly associated with treatment success (odds ratio = 3.923, 95% confidence interval = 1.53-10.04).

CONCLUSION

Our study demonstrates that Staphylococcus aureus was the most common causative organisms in PJI. Performing two-stage revisions was significantly associated with a better outcome.

Clinical outcome following surgical intervention for periprosthetic hip fractures at a tertiary referral centre

Complications following surgical intervention for periprosthetic hip fractures are not uncommon. We report the clinical outcome following definitive surgical intervention for this indication at a single tertiary referral centre. All patients admitted between 2003 and 2009 undergoing such treatment were included. Patient demographics, all surgical interventions, complications following definitive fracture treatment, and postoperative mortality were recorded. Radiographs were reviewed to determine the Vancouver classification for each fracture. There were 67 patients (mean age at revision 76.7 years; 61% female). Fractures occurred around primary total hip arthroplasties (43%), revision arthroplasties (34%), and hip hemiarthroplasties (23%). Mean time to fracture from the most recent arthroplasty performed was 7.0 years. Most fractures were Vancouver type B2 (49%). The majority of patients underwent revision total hip arthroplasty (96%), using long-stemmed prostheses or proximal femoral endoprostheses, with cables for fracture fixation. Wound infection and systemic complications were seen in 16% and 13% respectively. One or more further surgical interventions were performed in 12%. There were no deaths in-hospital or at 30-days, with 10 fatalities (15%) at a mean 2-year follow-up. Lower rates of re-intervention and mortality were observed when surgery for acute periprosthetic hip fractures was performed at a tertiary centre. Revision hip arthroplasty with or without fracture fixation proved an effective and safe treatment of periprosthetic hip fractures in a high-risk patient population.

The future of biologic coatings for orthopaedic implants

Implants are widely used for orthopaedic applications such as fixing fractures, repairing non-unions, obtaining a joint arthrodesis, total joint arthroplasty, spinal reconstruction, and soft tissue anchorage. Previously, orthopaedic implants were designed simply as mechanical devices; the biological aspects of the implant were a byproduct of stable internal/external fixation of the device to the surrounding bone or soft tissue. More recently, biologic coatings have been incorporated into orthopaedic implants in order to modulate the surrounding biological environment. This opinion article reviews current and potential future use of biologic coatings for orthopaedic implants to facilitate osseointegration and mitigate possible adverse tissue responses including the foreign body reaction and implant infection. While many of these coatings are still in the preclinical testing stage, bioengineers, material scientists and surgeons continue to explore surface coatings as a means of improving clinical outcome of patients undergoing orthopaedic surgery.

Bacterial colonization and resistance patterns in 133 patients undergoing a primary hip- or knee replacement in Southern Sweden

BACKGROUND AND PURPOSE

Prosthetic joint infections can be caused by bacteria derived from the patient's skin. The aim of the study was: (1) to determine which bacteria colonize the nose and groin in patients planned for primary hip or knee arthroplasty, (2) to determine the antimicrobial resistance patterns, and (3) to monitor changes in bacterial colonization and resistance patterns connected to surgery.

PATIENTS AND METHODS

2 weeks before scheduled primary hip or knee arthroplasty, culture samples were taken from the anterior nares and from the groin of 133 consecutive patients. At surgery, cloxacillin was given prophylactically and cement with gentamicin was used. 2 weeks after surgery, another set of samples were taken from 120 of these patients. Bacterial findings and resistance patterns were analyzed.

RESULTS

Preoperatively, 95% of the patients had coagulase-negative staphylococci (CNS) in the groin and 77% in the nose. The proportion of patients with a methicillin-resistant CNS in the groin increased from 20% preoperatively to 50% postoperatively (p < 0.001), and the proportion of patients with a gentamicin-resistant CNS in the groin increased from 5% to 45% (p < 0.001). 28% of the patients had Staphylococcus aureus in the nose preoperatively, and 7% in the groin. Methicillin-resistant Staphylococcus aureus (MRSA) was found in the nose of 1 patient.

INTERPRETATION

In southern Sweden, beta-lactams were effective against 99% of the Staphylococcus aureus strains and 80% of the CNS strains colonizing the patients undergoing primary hip or knee arthroplasty. Gentamicin protects against most CNS strains in cemented primary joint replacements.