The socioeconomic impact of musculoskeletal infections

Identifying potential predictive indicators for reimplantation timing in two-stage revision: a meta-analysis and system review

PURPOSE

The two-stage exchange revision represents a pivotal strategy in the management of prosthetic joint infections, wherein the judicious timing of reimplantation serves as a crucial determinant for therapeutic success. At present, attempts have been made to utilize predictive models to establish the optimal timing for reimplantation; however, their predictive accuracy remains unsatisfactory. This inadequacy primarily arises from the lack of dependable predictive indicators, which demonstrate inconsistent effectiveness across various studies and occasionally yield contradictory outcomes. Therefore, identifying solid predictive indicators is in desperate need.

METHODS

Studies reporting outcomes of the two-stage exchange revision till June, 2023 were systematically retrieved, screened and subject to quality analysis. Basic characteristics of these studies were firstly summarized. Subsequently, factors of interest regarding clinical information, blood and body fluid test results, pathogen test results of the recurrent and recurrent-free cohorts were extracted and submitted to a fixed or random effects model. Meanwhile, evaluation of publication bias and sensitivity was performed.

RESULTS

After filtering, a total of 45 studies were finally involved. Pooled analysis suggested that the recurrent cohort exhibited elevated incidences of body mass index (BMI) > 30, smoking and alcohol habits, diabetes, sinus tract, positive culture, and G-, polymicrobial and drug-resistant infections. Additionally, higher levels of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), synovial white blood cell (WBC) count, and polymorphonuclear percentage (PMN%) were observed in the recurrent cohort. On the other hand, the results of D-dimer and fibrinogen were ambiguous, and no difference regarding peripheral WBC count was observed. Forest plots suggested a low risk of publication bias. Besides, sensitivity analysis indicated good stability of the aforementioned indicators, except D-dimer and fibrinogen.

CONCLUSION

To sum up, BMI > 30, smoking and alcohol habits, diabetes, sinus tract, positive culture, and G-, polymicrobial and drug-resistant infections, CRP, ESR, synovial WBC and PMN% exhibited significant differences between recurrent and recurrent-free cohorts. Therefore, these indicators may be considered as potential predictive factors for the further development of a prognostic model that aids the determination of reimplantation timing. Nevertheless, the efficacy of these indicators remains to be further confirmed.

REGISTRATION NUMBER

Prospero ID: CRD42022296568.

Multidisciplinary Teams in Musculoskeletal Infection - From a Pathologist's Perspective

Multidisciplinary team (MDT) meetings have emerged as a promising approach for the treatment of cancer patients. These meetings involve a team of healthcare professionals from different disciplines working together to develop a holistic, patient-centered treatment. Although MDT meetings are well established in oncology, they play a minor role in other diseases. Recent evidence suggests that the implementation of MDT meetings can improve patient outcomes in musculoskeletal infections. The aim of this retrospective, observational study was to present the agenda of our multidisciplinary limb board including live microscopy with a special focus on the pathologist's role. The descriptive analysis of the limb board included 66 cases receiving live microscopy at the meeting and a total of 124 histopathological findings and 181 stainings. We could elucidate that pathologists seem to play an important role especially in clarifying the correct diagnosis. In 80.3 % of the findings, the pathologist specified the clinical diagnosis of the requesting physician leading to a consensus-based treatment plan for each patient. The implementation of MDT meetings including live microscopy in patients with musculoskeletal infections holds potential benefits, such as improved communication, scientific collaboration, and raising clinicians' awareness and understanding of histopathology findings. However, potential challenges, such as organizational effort and technical prerequisites should be considered.

Fellowship Training in Arthroplasty Improves Treatment Success of Debridement, Antibiotics, and Implant Retention for Periprosthetic Knee Infections

Background

Debridement, antibiotics, and implant retention (DAIR) is a well-accepted surgical strategy for periprosthetic joint infection (PJI) following total knee arthroplasty (TKA). DAIR in TKA may be incorrectly thought of as a "simple" procedure not requiring formal specialized training in arthroplasty. Currently, there are no studies comparing the risk of treatment failure based on surgeon fellowship training.

Methods

A retrospective review was performed of consecutive patients who underwent DAIR for TKA PJI at our institution. Two cohorts were created based on whether DAIR was performed by an arthroplasty fellowship-trained (FT) surgeon or nonarthroplasty fellowship-trained (NoFT) surgeon. Primary outcome was treatment failure following DAIR at a minimum of 1 year postoperatively. Treatment failure was based on the Tier 1 International Consensus Meeting definition of infection control. Secondary outcomes were also recorded including death during the totality of PJI treatment.

Results

A total of 112 patients were identified (FT = 68, NoFT = 44). At a mean follow-up of 7.3 years [standard deviation = 3.9], 73 patients (59.8%) failed treatment. Fellowship training in arthroplasty significantly improved treatment success rates (FT, 35/68 [51.5%]; NoFT, 10/44 [22.7%]; odds ratio 2.5 [95% confidence interval 1.1 to 5.9; P = .002]). Survivorship also differed significantly between the cohorts; at timepoints of 1.5 months, 5 months, 30 months, and 180 months, survivorship of the FT cohort was 79.4%, 67.6%, 54.4%, and 50.7%, respectively, compared with a survivorship of 65.9%, 52.3%, 25%, and 22.7% in the NoFT cohort (P = .002).

Conclusions

TKA PJI treated with DAIR should not be considered a simple procedure. Improved treatment success may be associated with subspecialty fellowship training in arthroplasty.

Level of Evidence

IV.

Interactions of Neutrophils with the Polymeric Molecular Components of the Biofilm Matrix in the Context of Implant-Associated Bone and Joint Infections

In the presence of orthopedic implants, opportunistic pathogens can easily colonize the biomaterial surfaces, forming protective biofilms. Life in biofilm is a central pathogenetic mechanism enabling bacteria to elude the host immune response and survive conventional medical treatments. The formation of mature biofilms is universally recognized as the main cause of septic prosthetic failures. Neutrophils are the first leukocytes to be recruited at the site of infection. They are highly efficient in detecting and killing planktonic bacteria. However, the interactions of these fundamental effector cells of the immune system with the biofilm matrix, which is the true interface of a biofilm with the host cells, have only recently started to be unveiled and are still to be fully understood. Biofilm matrix macromolecules consist of exopolysaccharides, proteins, lipids, teichoic acids, and the most recently described extracellular DNA. The latter can also be stolen from neutrophil extracellular traps (NETs) by bacteria, who use it to strengthen their biofilms. This paper aims to review the specific interactions that neutrophils develop when they physically encounter the matrix of a biofilm and come to interact with its polymeric molecular components.

Biofilms in Periprosthetic Orthopedic Infections Seen through the Eyes of Neutrophils: How Can We Help Neutrophils?

Despite advancements in our knowledge of neutrophil responses to planktonic bacteria during acute inflammation, much remains to be elucidated on how neutrophils deal with bacterial biofilms in implant infections. Further complexity transpires from the emerging findings on the role that biomaterials play in conditioning bacterial adhesion, the variety of biofilm matrices, and the insidious measures that biofilm bacteria devise against neutrophils. Thus, grasping the entirety of neutrophil-biofilm interactions occurring in periprosthetic tissues is a difficult goal. The bactericidal weapons of neutrophils consist of the following: ready-to-use antibacterial proteins and enzymes stored in granules; NADPH oxidase-derived reactive oxygen species (ROS); and net-like structures of DNA, histones, and granule proteins, which neutrophils extrude to extracellularly trap pathogens (the so-called NETs: an allusive acronym for "neutrophil extracellular traps"). Neutrophils are bactericidal (and therefore defensive) cells endowed with a rich offensive armamentarium through which, if frustrated in their attempts to engulf and phagocytose biofilms, they can trigger the destruction of periprosthetic bone. This study speculates on how neutrophils interact with biofilms in the dramatic scenario of implant infections, also considering the implications of this interaction in view of the design of new therapeutic strategies and functionalized biomaterials, to help neutrophils in their arduous task of managing biofilms.

Serum versus synovial fluid interleukin-6 for periprosthetic joint infection diagnosis: a systematic review and meta-analysis of 30 diagnostic test accuracy studies

BACKGROUND

Early and accurate detection of periprosthetic joint infection (PJI) after hip and/or knee arthroplasty remains challenging. This systematic review and meta-analysis of diagnostic test accuracy studies aimed to evaluate the diagnostic accuracy of serum and synovial fluid interleukin (IL)-6 in detecting PJI.

METHODS

We searched 3 databases for studies through December 31, 2021, using medical sub-headings terms and keywords. Studies reported sensitivity and specificity of serum and synovial fluid IL-6 in detecting PJI were considered. We calculated the pooled sensitivity, specificity, positive and negative likelihood ratio, diagnostic odds ratio (DOR), and the area under the summary receiver operating characteristic curve (AUC) to evaluate the diagnostic accuracy of serum and synovial fluid IL-6.

RESULTS

Thirty studies were included. The pooled sensitivity, specificity, positive and negative likelihood ratio, DOR, and AUC of serum IL-6 in detecting PJI were 0.76 (0.69-0.81), 0.88 (0.82-0.92), 6.2 (4.3-9.0), 0.28 (0.22-0.35), 22 (14-36), and 0.88 (0.85-0.91), respectively. However, synovial fluid IL-6 achieved a pooled sensitivity of 0.87 (0.75-0.93), specificity of 0.90 (0.85-0.93), positive and negative likelihood ratio of 8.5 (5.3-13.6) and 0.15 (0.08-0.29), DOR of 57 (21-156), and AUC of 0.94 (0.92-0.96), which were higher than serum IL-6.

CONCLUSIONS

Synovial fluid IL-6 test may be a promising test for PJI after hip and/or knee arthroplasty. However, considering the limited volume of synovial fluid and invasive acquisition of synovial fluid IL-6, serum IL-6 test may be also considered.

Silver-coated versus uncoated locking plates in subjects with fractures of the distal tibia: a randomized, subject and observer-blinded, multi-center non-inferiority study

BACKGROUND

Antimicrobial coatings of implants are of interest to reduce infection rate in orthopedic surgery. Demonstration of clinical effectiveness of such coated implants to obtain market approval is challenging. The objective of this article is to define a design for a randomized controlled trial to evaluate the clinical performance of a silver-coating for locking plates for fracture treatment.

METHODS

The study design has to respect different criteria, such as feasibility, focus on overall complications, such as functional impairment, fracture healing, and particularly on infection rates. Distal tibia fractures were chosen due to the high prevalence of infections in this type of injuries, which warrants a particular benefit of antimicrobial prophylaxis and thus might allow to see a statistical trend in favor of the coated product. The study design was defined as a randomized, controlled, subject and observer-blinded, multi-center study in subjects with fractures of the distal tibia with a total of 226 patients. A number of 113 patients are planned for each of the two treatment arms with treatment of the fracture with a silver-coated device (first arm) or with an uncoated device (second arm). Inclusion criteria are closed fractures of the distal tibia according to the Tscherne-Oestern classification or open fractures of the distal tibia according to the Gustilo-Anderson classification in subjects older than 18 years. Primary outcome parameter is the Anticipated Adverse Device Effects (AADE) including all typical complications of this type of injury, such as functional impairment of the affected limb, non-union, and infections based on a non-inferiority study design. Also, silver-typical complications, such as argyria, are included. Secondary parameters are infection rates and fracture healing. Follow-up of patients includes five visits with clinical and X-ray evaluations with a follow-up time of 12 months.

DISCUSSION

Demonstration of clinical effectiveness of antimicrobial coatings of fracture fixation devices remains a challenge. Definition of a prospective randomized pre-market trial design and recruitment of clinical sites for such a study is possible. A confirmative proof of the expected clinical benefit in terms of reduction of device-related infections will be addressed with a prospective post-market clinical follow-up study in a second step due to the large sample size required.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05260463. Registered on 02 March 2022.

International Survey of Practice for Prophylactic Systemic Antibiotic Therapy in Hip and Knee Arthroplasty

(1) Background: Prophylactic systemic antibiotics are acknowledged to be an important part of mitigating prosthetic joint infections. Controversy persists regarding optimal antibiotic regimes. We sought to evaluate current international antibiotics guidelines for total joint arthroplasty (TJA) of the hip and knee. (2) Methods: 42 arthroplasty societies across 6 continents were contacted and their published literature reviewed. (3) Results: 17 societies had guidelines; of which 11 recommended an antibiotic agent or antibiotic class (10—cephalosporin; 1—cloxacillin); 15 recommended antibiotic infusion within an hour of incision and 10 advised for post-operative doses (8—up to 24 h; 1—up to 36 h; 1—up to 48 h). (4) Conclusions: Prophylactic antibiotic guidelines for TJA are often absent or heterogenous in their advice.

Microbial resistance to nanotechnologies: An important but understudied consideration using antimicrobial nanotechnologies in orthopaedic implants

Microbial resistance to current antibiotics therapies is a major cause of implant failure and adverse clinical outcomes in orthopaedic surgery. Recent developments in advanced antimicrobial nanotechnologies provide numerous opportunities to effective remove resistant bacteria and prevent resistance from occurring through unique mechanisms. With tunable physicochemical properties, nanomaterials can be designed to be bactericidal, antifouling, immunomodulating, and capable of delivering antibacterial compounds to the infection region with spatiotemporal accuracy. Despite its substantial advancement, an important, but under-explored area, is potential microbial resistance to nanomaterials and how this can impact the clinical use of antimicrobial nanotechnologies. This review aims to provide a better understanding of nanomaterial-associated microbial resistance to accelerate bench-to-bedside translations of emerging nanotechnologies for effective control of implant associated infections.

Preoperative contrast-enhanced ultrasound (CEUS) of long bone nonunions reliably predicts microbiology of tissue culture samples but not of implant-sonication

INTRODUCTION

Bacterial infection in the context of fracture repair remains a severe complication in trauma surgery and may result in long bone nonunion. Since treatment options for aseptic and infected nonunions vary greatly, diagnostic methods should ideally differentiate between these two entities as accurately as possible. Recently, contrast-enhanced ultrasound (CEUS) has been introduced as a preoperative imaging technique to evaluate hypervascularity at the fracture site as sign of bacterial infection.

HYPOTHESIS

Preoperative CEUS predicts results of microbiological evaluation obtained either by culture of tissue samples or by analyzing the sonication fluid following removal and sonication of the implant.

PATIENTS AND METHODS

Over the course of 6 months, 26 patients with long bone nonunions were included in this study. Patients' clinical data were evaluated. Tissue samples were collected intraoperatively and examined by standard microbiological techniques. The sonication method was applied to removed implants. Additionally, 1-3 days before surgery, CEUS was performed to determine hypervascularity at the nonunion site as a possible parameter for infection.

RESULTS

Culture of tissue samples indicated infection in 50% of cases and implant sonication in 57.7% of cases. However, there was merely a fair agreement (κ=0.231) between these two diagnostic methods. CEUS predicted results of tissue culture reliably (sensitivity 92.3% and specificity 100%), whereas implant sonication showed no significant correlations with results from CEUS. Hypertrophic and atrophic nonunions were evaluated separately to determine possible differences in vascularity. We found that contrast peak enhancement of CEUS was similar in atrophic and hypertrophic nonunions with positive culture of tissue samples. Both differed significantly from culture negative cases (p=0.0016 and 0.0062). Results of implant-sonication positive or negative cases in atrophic and hypertrophic nonunions, however, were less clear and could be misleading.

DISCUSSION

We were able to confirm CEUS as a valuable preoperative diagnostic tool that reliably predicts microbiology of tissue culture samples, but not of implant sonication.

LEVEL OF EVIDENCE

I; diagnostic study.

Surface coating of orthopedic implant to enhance the osseointegration and reduction of bacterial colonization: a review

The use of orthopedic implants in surgical technology has fostered restoration of physiological functions. Along with successful treatment, orthopedic implants suffer from various complications and fail to offer functions correspondent to native physiology. The major problems include aseptic and septic loosening due to bone nonunion and implant site infection due to bacterial colonization. Crucial advances in material selection in the design and development of coating matrixes an opportunity for the prevention of implant failure. However, many coating materials are limited in in-vitro testing and few of them thrive in clinical tests. The rate of implant failure has surged with the increasing rates of revision surgery creating physical and sensitive discomfort as well as economic burdens. To overcome critical pathogenic activities several systematic coating techniques have been developed offering excellent results that combat infection and enhance bone integration. This review article includes some more common implant coating matrixes with excellent in vitro and in vivo results focusing on infection rates, causes, complications, coating materials, host immune responses and significant research gaps. This study provides a comprehensive overview of potential coating technology, with functional combination coatings which are focused on ultimate clinical practice with substantial improvement on in-vivo tests. This includes the development of rapidly growing hydrogel coating techniques with the potential to generate several accurate and precise coating procedures.

Prevalence of psychological comorbidities in bone infection

OBJECTIVE

Bone infections represent a major complication in orthopedic and trauma surgery. Concomitant psychological disorders can significantly influence treatment outcomes. However, these are often overlooked. Therefore, we aimed to determine the nationwide epidemiology of fracture-related infection (FRI) and osteomyelitis in combination with psychological comorbidities.

METHODS

A dataset provided by the Federal Statistical Office (Destatis) consisting of annual, Germany-wide ICD-10 diagnosis codes from 2009 to 2019 was analysed. Incidences of the codes "T84.6, infection and inflammatory reaction due to internal fixation device" and "M86.-, osteomyelitis" were quantified. Proportions of secondary diagnoses of the chapter F of the ICD-10 were determined.

RESULTS

Incidences were 19.1/100,000 inhabitants for osteomyelitis and 10.5/100,000 inhabitants for FRI. Patients with psychological comorbidities constituted 14.6% of osteomyelitis cases and 26.5% of FRI cases, respectively. Between 2009 through 2019, the proportion of patients with a concomitant "F" diagnoses of the ICD-10 increased by 27.3% for osteomyelitis and by 24.1% for FRI. Most prevalent secondary diagnoses were organic, including symptomatic, mental disorders (F0), affective disorder (F3) and mental and behavioral disorders due to psychoactive substance use (F1), whereby the latter decreased over the years.

CONCLUSION

The implementation of prevention strategies, interdisciplinary approaches and psychological support in orthopaedics and trauma surgery is warranted.

Contamination Associated With Glove Changing Techniques in the Operating Theatre

Background

Sterility of the operative field during surgery is imperative in reducing the risk of infection. Most commonly, double gloves are worn by surgeons. When contamination occurs, the top gloves are changed intra-operatively. No studies have investigated which glove changing technique is best. Therefore, in this study, we aim to identify which top glove changing technique causes the least surface contamination.

Methods

Glitterbug™ (UV fluorescent powder) was applied to the top gloves of 3 individuals who changed their top gloves according to a randomised method – Method 1: 3 pairs worn, remove the outer pair; Method 2: 2 pairs worn, remove the top glove, replace unassisted; and Method 3: 2 pairs worn, remove the top glove, and replace assisted by a scrub nurse. A blinded investigator inspected for Glitterbug™ contamination under UV light.

Results

Two hundred and ten trials were performed and two types of contamination were identified, namely, direct contact and airborne spread. For absolute contamination, Method 1 had 59/64 (92%) contaminated trials, Method 2 had 49/65 (75%) contaminated trials, and Method 3 had 64/81 (79%) contaminated trials. This was statistically significant (p = 0.031). For direct contamination only, Method 1 had 38/64 (59%) contaminated trials, Method 2 had 24/65 (37%) contaminated trials, and Method 3 had 20/81 (25%) contaminated trials. This was statistically significant (p < 0.0001).

Conclusions

Method 2 had a statistically significant lower contamination rate overall, with Method 3 having the lowest direct contamination rate. We believe that wearing 2 gloves, removing the top glove and replacing it, either assisted or unassisted, could decrease surface contamination of the sterile field.

The relationship of C-reactive protein/interleukin-6 concentrations between serum and synovial fluid in the diagnosis of periprosthetic joint infection

Background

The relationship of C-reactive protein (CRP)/interleukin-6 (IL-6) concentrations between serum and synovial fluid and whether synovial CRP/IL-6 testing in addition to serum CRP/IL-6 testing would result in a benefit in the diagnosis of periprosthetic joint infection (PJI) deserves to be investigated.

Methods

From June 2016 to July 2019, 139 patients were included in the study. Synovial CRP and IL-6 were tested by ELISA. The serum CRP and IL-6 were obtained from medical records. The definition of PJI was based on the modified Musculoskeletal Infection Society (MSIS) criteria. The relationship of serum and synovial CRP and IL-6 and the value of each index in the diagnosis of PJI were evaluated.

Results

The receiver operating characteristic (ROC) curves showed that synovial IL-6 had the highest area under the curve (AUC) at 0.935, which was followed by synovial CRP, serum IL-6 and serum CRP 0.861, 0.847 and 0.821, respectively. When combining serum CRP and synovial CRP to diagnose PJI, the AUC was 0.849, which was slightly higher than the result obtained when using serum CRP alone. In contrast, when combining serum IL-6 and synovial IL-6 to diagnose PJI, the AUC increased to 0.940, which was significantly higher than that obtained using serum IL-6 alone.

Conclusion

The synovial IL-6 has the highest diagnostic accuracy for PJI. However, inferring the level of CRP/IL-6 in the synovial fluid from the serum level of CRP/IL-6 was not feasible. Synovial CRP testing did not offer an advantage when combined with an existing serum CRP result to diagnose PJI, while additional synovial IL-6 was worthy of testing even if there was an existing serum IL-6 result.

Treatment of postoperative tibial chronic osteomyelitis using bone transport techniques; an observational study

PURPOSE

Postoperative Tibial chronic osteomyelitis is one of the most challenging orthopaedic conditions especially when extensive, the anatomy of subcutaneous anteromedial part of the tibia with less soft tissue coverage complicates the situation. The extent of infected tibial part varies in size and duration from one patient to another. We report our experience using Bifocal and Monofocal bone transport techniques with regard to clinical outcome, recurrence of infection and re-fracture rate.

METHODS

This is a retrospective observational review of 49 patients with postoperative Tibial chronic osteomyelitis which were treated using either Bifocal distraction compression BFDCO technique group I (31 patients) or Monofocal compression osteosynthesis MFCO technique Group II (18 patients). The average age of the patients was (41.6 ± 13.1 years), (range: 17-67 years). Leg length discrepancy was measured in 33 (58.9%) patients with an average of (1.4 ± 1.7 cm). Contracture of the ankle joint and equinus deformity were detected in 36 (64.3%) patients. Pre and Post-operative radiography together with Modified Irzhansky A.A et al. leg functional assessment system were used to assess the functional outcome.

RESULTS

The time spent in the Ilizarov fixator (External Fixation Index) in the first group was (142 ± 72 days) and in the second group was (75 ± 54 days). The infection recurred in 2 patients (6%) in group I and in 5 patients (28%) in group II. Lack of consolidation or re-fracture within 6 months after the dismantling of the apparatus was detected in 6 patients (19.5%) in group I and in 5 patients (27.8%) in group II. Lack of consolidation or re-fracture within 6 months after dismantling of the apparatus in group I was detected in 6 patients (19.5%) in group I and in 5 patients (27.8%) in Group II. The average functional state score (AFSS) in the first group was (12.45 ± 2.41) on admission and increased to (16.16 ± 2.99) on the final follow-up which corresponded to a "good" result. In the second group II the AFSS was (12.11 ± 2.22) on admission and increased to (15.06 ± 2.88) at the final follow-up which corresponded to a "satisfactory" result.

CONCLUSION

Treatment of Tibial chronic osteomyelitis using either Bifocal or Monofocal bone transport is an effective method. However our results have demonstrated better functional outcome and less infection recurrence and re-fracture rates when using the Bifocal distraction compression technique (BFDCO).

Management strategies for prosthetic joint infection: long-term infection control rates, overall survival rates, functional and quality of life outcomes

DAIR (debridement, antibiotics, and implant retention), one-stage and two-stage revision surgery are the most common management strategies for prosthetic joint infection (PJI) management. Our knowledge concerning their efficacy is based on short to medium-term low-quality studies.

Most studies report infection recurrence rates or infection-free time intervals. However, long-term survival rates of the infection-free joints, functional and quality of life outcome data are of paramount importance.

DAIR, one-stage and two-stage revision strategies are not unique surgical techniques, presenting several variables. Infection control rates for the above strategies vary from 75% to 90%, but comparisons are difficult because different indications and patient selection criteria are used in each strategy.

Recent outcome data show that DAIR and one-stage revision in selected patients (based on host, bacteriological, soft tissue and type of infection criteria) may present improved functional and quality of life outcomes and reduced costs for health systems as compared to those of two-stage revision.

It is expected that health system administrators and providers will apply pressure on surgeons and departments towards the wider use of DAIR and one-stage revision strategies. It is the orthopaedic surgeon’s responsibility to conduct quality studies in order to fully clarify the indications and outcomes of the different revision strategies.

Cite this article: EFORT Open Rev 2021;6:727-734. DOI: 10.1302/2058-5241.6.210008

Uncoated vs. Antibiotic-Coated Tibia Nail in Open Diaphyseal Tibial Fracture (42 according to AO Classification): A Single Center Experience

Implant-associated infections remain one of the main problems in the treatment of open tibia fractures. The role of systemic antibiotic prophylaxis is now agreed and accepted; nevertheless, recent literature also seems to emphasize the importance of local antibiotic therapy at the fracture site. Several therapeutic strategies have been proposed to overcome this new need. Antibiotic-coated nails play crucial role in this, allowing both infection prevention and favoring the fracture stabilization. We describe the outcome of patients with open diaphyseal tibia fracture treated either with a standard uncoated nail or a gentamicin-coated nail from January 2016 to December 2018 at our second level emergency-urgency department. Primary outcomes were infection rate and bone union rate. Other outcomes reported are reoperation rate, time between injury and nailing, and safety of antibiotic nail. Numerical variables were tabulated using mean, standard deviation, minimum, maximum, and number of observations. Categorical variables were tabulated using number of observations. 23 patients treated with uncoated nail and 23 patients treated with antibiotic-coated tibia nail were included in the study and were evaluated for a minimum follow-up of 18 months. Among the 46 patients, 9 were Gustilo-Anderson type I, 21 type II, and 16 type III open fracture. Regarding the bone healing rate at 12 months, 16 fractures in the first group and 18 in the second were completely healed. 4 infections were found in the first group (3 superficial surgical site infection and 1 osteomyelitis) and 3 superficial infections in the second one. No adverse events have been recorded with antibiotic-coated nails. In this unicentric retrospective study observed no deep wound infections and good fracture healing in the use of antibiotic-coated nails. Antibiotic nails have been shown to play a role in the treatment of fractures in critically ill patients with severe soft tissue damage.

Patient-specific effects of soluble factors from Staphylococcus aureus and Staphylococcus epidermidis biofilms on osteogenic differentiation of primary human osteoblasts

Due to the frequency of biofilm-forming Staphylococcus aureus and Staphylococcus epidermidis in orthopedics, it is crucial to understand the interaction between the soluble factors produced by prokaryotes and their effects on eukaryotes. Our knowledge concerning the effect of soluble biofilm factors (SBF) and their virulence potential on osteogenic differentiation is limited to few studies, particularly when there is no direct contact between prokaryotic and eukaryotic cells. SBF were produced by incubating biofilm from S. aureus and S. epidermidis in osteogenic media. Osteoblasts of seven donors were included in this study. Our results demonstrate that the detrimental effects of these pathogens do not require direct contact between prokaryotic and eukaryotic cells. SBF produced by S. aureus and S. epidermidis affect the metabolic activity of osteoblasts. However, the effect of SBF derived from S. aureus seems to be more pronounced compared to that of S. epidermidis. The influence of SBF of S. aureus and S. epidermidis on gene expression of COL1A1, ALPL, BGLAP, SPP1, RUNX2 is bacteria-, patient-, concentration-, and incubation time dependent. Mineralization was monitored by staining the calcium and phosphate deposition and revealed that the SBF of S. epidermidis markedly inhibits calcium deposition; however, S. aureus shows a less inhibitory effect. Therefore, these new findings support the hypotheses that soluble biofilm factors affect the osteogenic processes substantially, particularly when there is no direct interaction between bacteria and osteoblast.

Toll-like receptor activation of equine mesenchymal stromal cells to enhance antibacterial activity and immunomodulatory cytokine secretion

OBJECTIVE

To evaluate effects of Toll-like and nucleotide-binding oligomerization domain (NOD)-like receptor (TLR, NLR) ligand stimulation of equine mesenchymal stromal cells (MSCs) on antibacterial and immunomodulatory properties in vitro.

STUDY DESIGN

Controlled laboratory study.

SAMPLE POPULATION

Equine bone-marrow-derived MSCs (three horses).

METHODS

MSCs were stimulated with TLR (polyinosinic:polycytidylic acid [pIC] and lipopolysaccharide [LPS]) and NLR agonists (γ-d-Glu-mDAP [IE-DAP]) for 2 h, and plated at 1 × 10⁵ cells/well 24 h. MSC-conditioned media (MSC-CM) were collected and assessed for antimicrobial peptide cathelicidin/LL-37 production, bactericidal action against multidrug-resistant planktonic and biofilm Staphylococcus aureus and neutrophil phagocytosis. Bacterial growth was measured by plating bacteria and counting viable colonies, reading culture absorbance, and live-dead staining with confocal microscopy imaging. Following initial comparison of activating stimuli, TLR3-agonist pIC protocols (cell density during activation and plating, culture time, %serum) were further optimized for bactericidal activity and secretion of interleukin-8 (IL-8), monocyte-chemoattractant-protein (MCP-1), and cathelicidin/LL37.

RESULTS

MSCs stimulation with pIC (p = .004) and IE-DAP (p = .03) promoted increased bactericidal activity, evidenced by reduced viable planktonic colony counts. PIC stimulation (2 × 10⁶ cells/ml, 2 h, 10 μg/ml) further suppressed biofilm formation (p = .001), enhanced neutrophil bacterial phagocytosis (p = .009), increased MCP-1 secretion (p < .0001), and enhanced cathelicidin/LL-37 production, which was apparent when serum concentration in media was reduced to 1% (p = .01) and 2.5% (p = .05).

CONCLUSION

TLR-3 pIC MSCs activation was most effective to enhance antibacterial and cytokine responses, which were affected by serum reduction.

CLINICAL SIGNIFICANCE

In vitro TLR-3 activation of equine MSCs tested here may be a strategy to improve antibacterial properties of MSCs to treat antibiotic-resistant infections.

Development of a Preoperative Risk Calculator for Reinfection Following Revision Surgery for Periprosthetic Joint Infection

BACKGROUND

A recent systematic review demonstrated that reinfection rates following eradication of hip and knee periprosthetic joint infection (PJI) may be as high as 29%. This study aimed to develop a preoperative risk calculator for assessing patient's individual risk associated with reinfection following treatment of PJI in total joint arthroplasty (TJA).

METHODS

A total of 1081 consecutive patients who underwent revision TJA for PJI were evaluated. In total, 293 patients were diagnosed with TJA reinfection. A total of 56 risk factors, including patient characteristics and surgical variables, were evaluated with multivariate regression analysis. Analysis of the area under the receiver operating characteristics curve was performed to evaluate the strength of the predictive model.

RESULTS

Of the 56 risk factors studied, 19 were found to have a significant effect as risk factor for TJA reinfection. The strongest predictors for TJA reinfection included previous PJI treatment techniques such as irrigation and debridement, the number of previous surgical interventions, medical comorbidities such as obesity, drug abuse, depression and smoking, as well as microbiology including the presence of Enterococcus species. The combined area under the receiver operating characteristics curve of the risk calculator for periprosthetic hip and knee joint reinfection was 0.75.

CONCLUSIONS

The study findings demonstrate that surgical factors, including previous PJI surgical treatment techniques as well as the number of previous surgeries, alongside microbiology including the presence of Enterococcus species have the strongest effect on the risk for periprosthetic THA and TKA joint reinfection, suggesting the limited applicability of the existing risk calculators for the development of PJI following primary TJA in predicting the risk of periprosthetic joint reinfection.

Similar risk of complete revision for infection with single-dose versus multiple-dose antibiotic prophylaxis in primary arthroplasty of the hip and knee: results of an observational cohort study in the Dutch Arthroplasty Register in 242,179 patients

Background and purpose - The optimal type and duration of antibiotic prophylaxis for primary arthroplasty of the hip and knee are subject to debate. We compared the risk of complete revision (obtained by a 1- or 2-stage procedure) for periprosthetic joint infection (PJI) after primary total hip or knee arthroplasty between patients receiving a single dose of prophylactic antibiotics and patients receiving multiple doses of antibiotics for prevention of PJI. Patients and methods - A cohort of 130,712 primary total hip and 111,467 knee arthroplasties performed between 2011 and 2015 in the Netherlands was analyzed. We linked data from the Dutch arthroplasty register to a survey collected across all Dutch institutions on hospital-level antibiotic prophylaxis policy. We used restricted cubic spline Poisson models adjusted for hospital clustering to compare the risk of revision for infection according to type and duration of antibiotic prophylaxis received. Results - For total hip arthroplasties, the rates of revision for infection were 31/10,000 person-years (95% CI 28-35), 39 (25-59), and 23 (15-34) in the groups that received multiple doses of cefazolin, multiple doses of cefuroxime, and a single dose of cefazolin, respectively. The rates for knee arthroplasties were 27/10,000 person-years (95% CI 24-31), 40 (24-62), and 24 (16-36). Similar risk of complete revision for infection among antibiotic prophylaxis regimens was found when adjusting for confounders. Interpretation - In a large observational cohort we found no apparent association between the type or duration of antibiotic prophylaxis and the risk of complete revision for infection. This does question whether there is any advantage to the use of prolonged antibiotic prophylaxis beyond a single dose.

Characteristics of Antibiotic Prophylaxis and Risk of Surgical Site Infections in Primary Total Hip and Knee Arthroplasty

BACKGROUND

Despite numerous antibiotic prophylaxis options for total hip arthroplasty (THA) and total knee arthroplasty (TKA), an assessment of practice patterns and comparative effectiveness is lacking. We aimed to characterize antibiotic utilization patterns and associations with infection risk and hypothesized differences in infection risk based on regimen.

METHODS

A retrospective cohort study was performed using data from 436,724 THA and 862,918 TKA (Premier Healthcare Database; 2006-2016). Main exposures were antibiotic type and duration: day of surgery only (day 0) or through postoperative day 1 (day 1). The primary outcome was surgical site infection (SSI) <30 days postoperation. Mixed-effect models measured associations between prophylaxis regimen and SSI as odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

SSI prevalence was 0.21% (n = 914) for THA and 0.22% (n = 1914) for TKA. Among THA procedures, the most commonly used antibiotics were cefazolin (74.1%), vancomycin (8.4%), "other" antibiotic combinations (7.1%), vancomycin + cefazolin (5.1%), and clindamycin (3.3%). Here, 51.8% received prophylaxis on day 0 only, whereas 48.2% received prophylaxis through day 1. Similar patterns existed for TKA. Relative to cefazolin, higher SSI odds were seen with vancomycin (OR = 1.36; CI 1.09-1.71) in THA and with vancomycin (OR = 1.29; CI = 1.10-1.52), vancomycin + cefazolin (OR = 1.35; CI = 1.12-1.64), clindamycin (OR = 1.38; CI = 1.11-1.71), and "other" antibiotic combinations (OR = 1.28; CI = 1.07-1.53) in TKA. Prophylaxis duration did not alter SSI odds. Results were corroborated in sensitivity analyses.

CONCLUSION

Antibiotic prophylaxis regimens other than cefazolin were associated with increased SSI risk among THA/TKA patients. These findings emphasize a modifiable intervention to mitigate infection risk.

Prevalence and burden of orthopaedic implantable-device infections in Italy: a hospital-based national study

BACKGROUND

Healthcare-associated infections (HAIs) represent a serious burden to individual safety and healthcare sustainability. Identifying which patients, procedures and settings are most at risk would offer a significant contribution to HAI management and prevention. The purpose of this study is to estimate 1) orthopaedic implantable device-related infection (OIDRI) prevalence in Italian hospitals and 2) the gap between the remuneration paid by the Italian healthcare system and the real costs sustained by Italian hospitals to treat these episodes.

METHODS

This is a cross-sectional study based on hospital discharge forms registered in 2012 and 2014. To address the first goal of this study, the national database was investigated to identify 1) surgical procedures associated with orthopaedic device implantation and 2) among them, which patient characteristics (age, sex), type of admission, and type of discharge were associated with a primary diagnosis of infection. To address the second goal, 1) each episode of infection was multiplied by the remuneration paid by the Italian healthcare system to the hospitals, based on the diagnosis-related group (DRG) system, and 2) the total days of hospitalization required to treat the same episodes were multiplied by the average daily cost of hospitalization, according to estimates from the Ministry of the Economy and Finance (MEF).

RESULTS

In 2014, 1.55% of the total hospitalizations for orthopaedic device implantation procedures were associated with a main diagnosis of infection, with a negligible increase of 0.04% compared with 2012. Hip and knee replacement revisions, male patients and patients older than 65 years were more exposed to infection. A total of 51.63% of patients were planned admissions to the hospital, 68.75% had an ordinary discharge to home, and 0.9% died. The remuneration paid by the healthcare system to the hospitals was € 37,519,084 in 2014, with 3 DRGs covering 70.6% of the total. The cost of the actual days of hospitalization to treat these episodes was 17.5 million more than the remuneration received.

CONCLUSIONS

The OIDRI prevalence was lower than that described in recent surveys in acute care settings, although the numbers were likely underestimated. The cost of treatment varied significantly depending on the remuneration system adopted.

Antibacterial coating of implants: are we missing something?

Implant-related infection is one of the leading reasons for failure in orthopaedics and trauma, and results in high social and economic costs. Various antibacterial coating technologies have proven to be safe and effective both in preclinical and clinical studies, with post-surgical implant-related infections reduced by 90% in some cases, depending on the type of coating and experimental setup used. Economic assessment may enable the cost-to-benefit profile of any given antibacterial coating to be defined, based on the expected infection rate with and without the coating, the cost of the infection management, and the cost of the coating. After reviewing the latest evidence on the available antibacterial coatings, we quantified the impact caused by delaying their large-scale application. Considering only joint arthroplasties, our calculations indicated that for an antibacterial coating, with a final user's cost price of €600 and able to reduce post-surgical infection by 80%, each year of delay to its large-scale application would cause an estimated 35 200 new cases of post-surgical infection in Europe, equating to additional hospital costs of approximately €440 million per year. An adequate reimbursement policy for antibacterial coatings may benefit patients, healthcare systems, and related research, as could faster and more affordable regulatory pathways for the technologies still in the pipeline. This could significantly reduce the social and economic burden of implant-related infections in orthopaedics and trauma. Cite this article: C. L. Romanò, H. Tsuchiya, I. Morelli, A. G. Battaglia, L. Drago. Antibacterial coating of implants: are we missing something? Bone Joint Res 2019;8:199-206. DOI: 10.1302/2046-3758.85.BJR-2018-0316.

Surgical masks as source of bacterial contamination during operative procedures

Background

Surgical masks (SMs) are used to reduce bacterial shedding from the mouth, nose and face. This study aimed to investigate whether SMs may be a potential source of bacterial shedding leading to an increased risk of surgical site infection.

Methods

Bacterial contamination of the SMs was tested by making an impression of the external surface of the mask on sterile culture media immediately. We investigated the difference in bacterial counts between the SMs worn by surgeons and those placed unused in the operating room (OR), and the bacterial count variation with indicated wearing time. Moreover, the difference in bacterial counts on the external surface between the first and second layers of double-layered SMs was also assessed.

Results

The bacterial count on the surface of SMs increased with extended operating times; significant difference was found between the 4- to 6-hour and 0-hour groups (p < 0.05). When we analysed the bacterial counts from the same surgeon, a significant increase was noted in the 2-hours group. Moreover, the bacterial counts were significantly higher among the surgeons than the OR. Additionally, the bacterial count of the external surface of the second mask was significantly higher than that of the first one.

Conclusions

The source of bacterial contamination in SMs was the body surface of the surgeons rather than the OR environment. Moreover, we recommend that surgeons should change the mask after each operation, especially those beyond 2 hours. Double-layered SMs or those with excellent filtration function may also be a better alternative.

The translational potential of this article

This study provides strong evidence for the identification that SMs as source of bacterial contamination during operative procedures, which should be a cause for alarm and attention in the prevention of surgical site infection in clinical practice.

BAG-S53P4 as bone graft extender and antimicrobial activity against gentamicin- and vancomycin-resistant bacteria

AIM

To evaluate the suitability of bioactive glass (BAG)-S53P4 as a bone-graft extender for large bony defect filling in bone and joint infection.

MATERIALS & METHODS

Antimicrobial activity of BAG-S53P4 against clinically relevant strains isolated from bone and joint infections was evaluated by means of time-kill curves in presence of bone graft. Furthermore, the susceptibility to BAG of strains resistant to vancomycin and gentamicin was assessed.

RESULTS

Though attenuated, BAG maintains a good in vitro antimicrobial activity in presence of human body fluids and tissues contained in bone graft, with the exception of Enterococcus faecalis.

CONCLUSION

BAG-S53P4 is a suitable bone substitute that can be used as an extender with autologous bone graft to promote better fusion and healing.

Initial peri- and postoperative antibiotic treatment of infected nonunions: results from 212 consecutive patients after mean follow-up of 34 months

PURPOSE

Infected nonunions of the long bones belong to the most feared complications in the field of orthopedic and trauma surgery. Optimal antibiotic therapy should start early with the first revision surgery. Therefore, the aim of this study was to evaluate our peri- and postoperative antibiotic regime in context with the microbial spectrum and antibiotic resistances of patients with infected nonunions and to assess the possible impact on healing rates.

METHODS

We included all patients with first revision surgery during 2010-2015 due to nonunion of long bones with a clinical history of infection treated with radical debridement, local application of a gentamicin-impregnated bone cement, and systemic cefuroxime. Mean follow-up was 34.2 months. Data collection was performed retrospectively using a computerized databank with information about microbial species from intraoperatively acquired tissue samples and respective antibiograms. Bone fusion rates were evaluated based on findings of the latest X-rays and computed tomography scans.

RESULTS

Two hundred and twelve patients with nonunion and history of infection were selected; 171 patients had positive intraoperative microbial evidence of infection. Bacterial testing was mostly positive in fractures of the tibia (47.4%) and the femur (27.5%). Coagulase-negative Staphylococcus spp. were the most frequently detected (44.4%) followed by mixed infections (18.7%) and Staphylococcus aureus (10.5%). Antibiograms revealed that 62.6% of our cases were cefuroxime sensitive; 87.7% were gentamicin sensitive. Only 10.5% showed resistance to both cefuroxime and gentamicin. There was no statistically significant difference of fusion rates between patients with different microbial species or different antibiograms.

CONCLUSION

Our data suggest that besides the high variety of different detected species, initial antibiotic treatment with a combination of systemic cefuroxime and local gentamicin-loaded bone cement is effective and in almost 90% the later determined microbial infection was sensitive to this treatment. Therefore, we recommend initial treatment according to this algorithm until specific antibiograms are available from intraoperatively acquired tissue samples.

Surgical site infections following instrumented stabilization of the spine

Background

Implant-associated infections are still a feared complication in the field of orthopedics. Bacteria attach to the implant surface and form so-called biofilm colonies that are often difficult to diagnose and treat. Since the majority of studies focus on prosthetic joint infections (PJIs) of the hip and knee, current treatment options (eg, antibiotic prophylaxis) of implant-associated infections have mostly been adapted according to these results.

Objective

The aim of this study was to evaluate patients with surgical site infections following instrumented stabilization of the spine with regard to detected bacteria species and the course of the disease.

Patients and methods

We performed a retrospective single-center analysis of implant-associated infections of the spine from 2010 to 2014. A total of 138 patients were included in the study. The following parameters were evaluated: C-reactive protein serum concentration, microbiological evaluation of tissue samples, the time course of the disease, indication for instrumented stabilization of the spine, localization of the infection, and the number of revision surgeries required until cessation of symptoms.

Results

Coagulase-negative Staphylococcus spp. were most commonly detected (n=69, 50%), followed by fecal bacteria (n=46, 33.3%). In 23.2% of cases, no bacteria were detected despite clinical suspicion of an infection. Most patients suffered from degenerative spine disorders (44.9%), followed by spinal fractures (23.9%), non-degenerative scoliosis (20.3%), and spinal tumors (10.1%). Surgical site infections occurred predominantly within 3 months (64.5%), late infections after 2 years were rare (4.3%), in particular when compared with PJIs. Most cases were successfully treated after 1 revision surgery (60.9%), but there were significant differences between bacteria species. Fecal bacteria were more difficult to treat and often required more than 1 revision surgery.

Conclusion

In summary, we were able to demonstrate significant differences between spinal implant-associated infections and PJIs. These aspects should be considered early on in the treatment of surgical site infections following instrumented stabilization of the spine.

Understanding long-term silver release from surface modified porous titanium implants

Prevention of orthopedic device related infection (ODRI) using antibiotics has met with limited amount of success and is still a big concern during post-surgery. As an alternative, use of silver as an antibiotic treatment to prevent surgical infections is being used due to the well-established antimicrobial properties of silver. However, in most cases silver is used in particulate form with wound dressings or with short-term devices such as catheters but not with load-bearing implants. We hypothesize that strongly adherent silver to load-bearing implants can offer longer term solution to infection in vivo. Keeping that in mind, the focus of this study was to understand the long term release study of silver ions for a period of minimum 6months from silver coated surface modified porous titanium implants. Implants were fabricated using a LENS™ system, a powder based additive manufacturing technique, with at least 25% volume porosity, with and without TiO2 nanotubes in phosphate buffer saline (pH 7.4) to see if the total release of silver ions is within the toxic limit for human cells. Considering the fact that infection sites may reduce the local pH, silver release was also studied in acetate buffer (pH 5.0) for a period of 4weeks. Along with that, the osseointegrative properties as well as cytotoxicity of porous titanium implants were assessed in vivo for a period of 12weeks using a rat distal femur model. In vivo results indicate that porous titanium implants with silver coating show comparable, if not better, biocompatibility and bonding at the bone-implant interface negating any concerns related to toxicity related to silver to normal cells. The current research is based on our recently patented technology, however focused on understanding longer-term silver release to mitigate infection related problems in load-bearing implants that can even arise several months after the surgery.

STATEMENT OF SIGNIFICANCE

Prevention of orthopedic device related infection using antibiotics has met with limited success and is still a big concern during post-surgery. Use of silver as an antibiotic treatment to prevent surgical infections is being explored due to the well-established antimicrobial properties of silver. However, in most cases silver is used in particulate form with wound dressings or with short-term devices such as catheters but not with load-bearing implants. We hypothesize that strongly adherent silver to load-bearing implants can offer longer-term solution towards infection in vivo. Keeping that in mind, the focus of this study was to understand the long-term release of silver ions, for a period of minimum 6months, from silver coated surface modified porous titanium implants.

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.

Sustained release vancomycin-coated titanium alloy using a novel electrostatic dry powder coating technique may be a potential strategy to reduce implant-related infection

In order to tackle the implant-related infection, a novel way was developed in this study to coat vancomycin particles mixed with controlled release coating materials onto the surface of titanium alloy by using an electrostatic dry powder coating technique. To characterize this sustained release antibacterial coating, surface morphology, in vitro and in vivo drug release were sequentially evaluated. In vitro cytotoxicity was tested by Cell Counting Kit-8 (CCK-8) assay and cytological changes were observed by inverted microscope. The antibacterial properties against MRSA, including a bacterial growth inhibition assay and a colony-counting test by spread plate method were performed. Results indicated that the vancomycin-coated sample was biocompatible for Human osteoblast cell line MG-63 and displayed effective antibacterial ability against MRSA. The coating film was revealed uniform by scanning electron microscopy. Both the in vitro and in vivo drug release kinetics showed an initially high release rate, followed by an extended period of sustained drug release over 7 days. These results suggest that with good biocompatibility and antibacterial ability, the sustained release antibacterial coating of titanium alloy using our novel electrostatic dry powder coating process may provide a promising candidate for the treatment of orthopedic implant-related infection.

Antimicrobial coated implants in trauma and orthopaedics-A clinical review and risk-benefit analysis

Implant-associated infections remain a major issue in orthopaedics and antimicrobial functionalization of the implant surface by antibiotics or other anti-infective agents have gained interest. The goal of this article is to identify antimicrobial coatings, for which clinical data are available and to review their clinical need, safety profile, and their efficacy to reduce infection rates. PubMed database of the National Library of Medicine was searched for clinical studies on antimicrobial coated implants for internal fracture fixation devices and endoprostheses for bone surgery, for which study design, level of evidence, biocompatibility, development of resistance, and effectiveness to reduce infection rates were analyzed. Four different coating technologies were identified: gentamicin poly(d, l-lactide) coating for tibia nails, one high (MUTARS^®) and one low amount silver (Agluna) technology for tumor endoprostheses, and one povidone-iodine coating for titanium implants. There was a total of 9 published studies with 435 patients, of which 7 studies were case series (level IV evidence) and 2 studies were case control studies (level III evidence). All technologies were reported with good systemic and local biocompatibility, except the development of local argyria with blue to bluish grey skin discoloration after the use of silver MUTARS^® megaendoprostheses. For the local use of gentamicin, there is contradictory data on the risk of emergence of gentamicin-resistance strains, a risk that does not seem to exist for silver and iodine based technologies. Regarding reduction of infection rates, one case control study showed a significant reduction of infection rates by Agluna silver coated tumor endoprostheses. Based on socio-economic data, there is a strong need for improvement of infection prevention and treatment strategies, including implant coatings, in fracture care, primary and revision arthroplasty, and bone tumor surgery. The reviewed gentamicin, silver Agluna, and povidone-iodine technologies have shown a good risk benefit ratio for patients. Further data from randomized control trials are desirable, although this will remain challenging in the context of infection prevention due to the required large sample size of such studies.

Hyaluronic Acid and Its Composites as a Local Antimicrobial/Antiadhesive Barrier

Living in biofilms is probably the most common condition for bacteria and fungi and biofilm-related infections account for the majority of bacterial infectious diseases worldwide. Among others biofilm-related infections, those associated with implanted biomaterials have an enormous and still largely underestimated impact in orthopaedics and trauma, cardio-surgery and several other surgical disciplines. Given the limited efficacy of existing antibiotics in the prevention and treatment of bacterial biofilms, new strategies are needed to protect implants and host tissues, overcoming the striking ability of the microorganisms to adhere on different surfaces and to immediately protect themselves by forming the biofilm matrix. Adhesion is a necessary first step in microbial colonization and pathogenesis and provides a potential target for new preventive and treatment approach. Among various polymers, tested as antibacterial coatings, hyaluronic acid and some of its composites do offer a well-established long-term safety profile and a proven ability to reduce bacterial adhesion and biofilm formation. Aim of the present review is to summarize the available evidence concerning the antiadhesion/antibiofilm activity of hyaluronic acid and some of its derivatives to reduce/prevent bacterial adhesion and biofilm formation in various experimental and clinical settings.

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.

The osteoblast as an inflammatory cell: production of cytokines in response to bacteria and components of bacterial biofilms

BACKGROUND

Implant infections are a major complication in the field of orthopaedics. Bacteria attach to the implant-surface and form biofilm-colonies which makes them difficult to treat. Not only immune cells exclusively respond to bacterial challenges, but also local tissue cells are capable of participating in defense mechanisms. The aim of this study was to evaluate the role of osteoblasts in the context of implant infections.

METHODS

Primary osteoblasts were cultivated and stimulated with free-swimming bacteria at 4 °C and 37 °C. Supernatants were harvested for ELISA and expression of pro-inflammatory cytokines evaluated by RT-PCR. Bacterial binding to osteoblasts was evaluated using cytofluorometry and uptake was investigated by (3)H thymidine-labelling of bacteria. Osteoblasts were additionally stimulated with the extracellular polymeric substance (EPS) of Staphylococcus epidermidis biofilms, as well as components of the EPS; the bacterial heat shock protein GroEL in particular.

RESULTS

We demonstrated that binding of bacteria to the osteoblast cell surface leads to an increased production of pro-inflammatory cytokines. Bacteria are capable of surviving intracellular. Furthermore, osteoblasts do not only respond to free-swimming, planktonic bacteria, but also to components of the EPS, including lipoteichoic acid and the heat shock protein GroEL.

CONCLUSION

In conclusion, local tissue cells, specifically osteoblasts, might contribute to the persistence of the inflammatory response associated with implant-infections.

Gentamicin coating of plasma chemical oxidized titanium alloy prevents implant-related osteomyelitis in rats

Implant related infection is one of the most feared and devastating complication associated with the use of orthopaedic implant devices. Development of anti-infective surfaces is the main strategy to prevent implant contamination, biofilm formation and implant related osteomyelitis. A second concern in orthopaedics is insufficient osseointegration of uncemented implant devices. Recently, we reported on a macroporous titanium-oxide surface (bioactive TiOB) which increases osseointegration and implant fixation. To combine enhanced osseointegration and antibacterial function, the TiOB surfaces were, in addition, modified with a gentamicin coating. A rat osteomyelitis model with bilateral placement of titanium alloy implants was employed to analyse the prophylactic effect of gentamicin-sodiumdodecylsulfate (SDS) and gentamicin-tannic acid coatings in vivo. 20 rats were randomly assigned to four groups: (A) titanium alloy; PBS inoculum (negative control), (B) titanium alloy, Staphylococcus aureus inoculum (positive control), (C) bioactive TiOB with gentamicin-SDS and (D) bioactive TiOB plus gentamicin-tannic acid coating. Contamination of implants, bacterial load of bone powder and radiographic as well as histological signs of implant-related osteomyelitis were evaluated after four weeks. Gentamicin-SDS coating prevented implant contamination in 10 of 10 tibiae and gentamicin-tannic acid coating in 9 of 10 tibiae (infection prophylaxis rate 100% and 90% of cases, respectively). In Group (D) one implant showed colonisation of bacteria (swab of entry point and roll-out test positive for S. aureus). The interobserver reliability showed no difference in the histologic and radiographic osteomyelitis scores. In both gentamicin coated groups, a significant reduction of the histological osteomyelitis score (geometric mean values: C = 0.111 ± 0.023; D = 0.056 ± 0.006) compared to the positive control group (B: 0.244 ± 0.015; p < 0.05) was observed. The radiographic osteomyelitis scores confirmed these histological findings.

Innate Immune Response in Implant-Associated Infections: Neutrophils against Biofilms

Biofilm has been recognized as a well-protected form of living for bacteria, contributing to bacterial pathogenicity, particularly for opportunistic species. Biofilm-associated infections are marked by their persistence. Extensive research has been devoted to the formation and composition of biofilms. The immune response against biofilms remains rather unexplored, but there is the notion that bacteria within a biofilm are protected from host defences. Here we glance at the mechanisms by which neutrophils recognize and face biofilms in implant infections and discuss the implications of this interplay, as well as speculate on its significance.

Orthopaedic device-related infection: current and future interventions for improved prevention and treatment

Orthopaedic and trauma device-related infection (ODRI) remains one of the major complications in modern trauma and orthopaedic surgery.Despite best practice in medical and surgical management, neither prophylaxis nor treatment of ODRI is effective in all cases, leading to infections that negatively impact clinical outcome and significantly increase healthcare expenditure.The following review summarises the microbiological profile of modern ODRI, the impact antibiotic resistance has on treatment outcomes, and some of the principles and weaknesses of the current systemic and local antibiotic delivery strategies.The emerging novel strategies aimed at preventing or treating ODRI will be reviewed. Particular attention will be paid to the potential for clinical impact in the coming decades, when such interventions are likely to be critically important.The review focuses on this problem from an interdisciplinary perspective, including basic science innovations and best practice in infectious disease. Cite this article: Moriarty TF, Kuehl R, Coenye T, et al. Orthopaedic device related infection: current and future interventions for improved prevention and treatment. EFORT Open Rev 2016;1:89-99. DOI: 10.1302/2058-5241.1.000037.

Are atrophic long-bone nonunions associated with low-grade infections?

Impaired fracture healing, especially when associated with bacterial infection, is a severe complication following long-bone fractures and requires special treatment. Because standard diagnostic techniques might provide falsely negative results, we evaluated the sonication method for detection of bacteria on implants of patients with fracture nonunions. A total of 49 patients with a nonunion (group NU) and, for comparison, 45 patients who had undergone routine removal of osteosynthetic material (group OM), were included in the study. Five different diagnostic methods (culture of tissue samples, culture of intraoperative swabs, histopathology of tissue samples, culture of sonication fluid, and 16S ribosomal DNA polymerase chain reaction of sonication fluid) were compared and related to clinical data. Among the diagnostic tests, culture of sonication fluid demonstrated by far the highest detection rate of bacteria (57%) in group NU, and rather unexpectedly 40% in group OM. Culture of sonication samples also revealed a broad spectrum of bacteria, in particular Propionibacterium spp. In conclusion, our results indicate that more bacteria can be detected on implants of patients with atrophic nonunions of long-bone fractures by means of the sonication procedure, which provides a valuable additional diagnostic tool to decide on a surgical procedure (eg, two-step procedure) and to further specify antimicrobial therapy.

Risk Factors for Recurrence of Periprosthetic Knee Infection

We retrospectively reviewed 110 patients who underwent two-stage revision surgery in order to identify potential risk factors for recurrence of periprosthetic infection. We found that patients with inflammatory arthritis (P=0.0125), perioperative hematoma formation (P=0.0422), wound dehiscence (P=0.042), and those who are chronic Staphylococcus carriers (P=0.0177) were associated with an increased incidence of re-infection. The duration of intravenous antibiotic therapy less than 6 weeks was associated with a reduced risk of reinfection to greater than 6 weeks (P=0.03). Multivariate analysis indicated that wound dehiscence (odds ratio [OR], 5.119; 95% confidence interval [CI], 1.367-19.17), and Staphylococcus carriers (OR, 11.419; 95% CI, 1.376-94.727) are significant predictors of recurrence (P=0.0153 and 0.0241, respectively).

Postoperative antibiotic prophylaxis in total hip and knee arthroplasty: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Postoperative antibiotic prophylaxis is currently the standard of care for patients undergoing total hip and knee arthroplasty. We evaluated the evidence for this practice in the reduction of surgical-site infections.

METHODS

We systematically searched MEDLINE, Embase and the Cochrane Library for randomized controlled trials (RCTs) published up to Aug. 15, 2014. We included all RCTs that compared postoperative antibiotic prophylaxis with postoperative placebo or no treatment in patients undergoing primary total hip or knee arthroplasty for osteoarthritis. We combined outcomes for surgical-site infection using a random-effects model and quantified heterogeneity using the χ2 test and the I2 statistic. We assessed the overall quality of the evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

We identified 4 RCTs (n = 4036) that met the inclusion criteria. Surgical-site infections occurred in 3.1% (63/2055) of patients in the prophylaxis group and 2.3% (45/1981) in the control group. Postoperative prophylaxis did not reduce the rate of surgical-site infections compared with placebo (risk difference 0.01, 95% confidence interval 0.00 to 0.02; I2 = 26%). This result was robust to sensitivity testing for losses to follow-up. According to the GRADE approach, the overall quality of evidence was very low.

INTERPRETATION

The available evidence did not show efficacy of postoperative antibiotic prophylaxis for the prevention of surgical-site infections in patients undergoing total hip or knee arthroplasty. Multicentred RCTs are likely to have an important impact on the confidence in the effect estimate and to change the estimate itself.

RhBMP-7 for the treatment of nonunion of fractures of long bones

We report the outcome of 84 nonunions involving long bones which were treated with rhBMP-7, in 84 patients (60 men: 24 women) with a mean age 46 years (18 to 81) between 2003 and 2011. The patients had undergone a mean of three previous operations (one to 11) for nonunion which had been present for a mean of 17 months (4 months to 20 years). The nonunions involved the lower limb in 71 patients and the remainder involved the upper limb. A total of 30 nonunions were septic. Treatment was considered successful when the nonunion healed without additional procedures. The relationship between successful union and the time to union was investigated and various factors including age and gender, the nature of the nonunion (location, size, type, chronicity, previous procedures, infection, the condition of the soft tissues) and type of index procedure (revision of fixation, type of graft, amount of rhBMP-7) were analysed. The improvement of the patients' quality of life was estimated using the Short Form (SF) 12 score. A total of 68 nonunions (80.9%) healed with no need for further procedures at a mean of 5.4 months (3 to 10) post-operatively. Multivariate logistic regression analysis of the factors affecting union suggested that only infection significantly affected the rate of union (p = 0.004).Time to union was only affected by the number of previous failed procedures (p = 0.006). An improvement of 79% and 32.2% in SF-12 physical and mental score, respectively, was noted within the first post-operative year. Rh-BMP-7 combined with bone grafts, enabled healing of the nonunion and improved quality of life in about 80% of patients. Aseptic nonunions were much more likely to unite than septic ones. The number of previous failed operations significantly delayed the time to union.

Abdominal Hysterectomy: Reduced Risk of Surgical Site Infection Associated with Robotic and Laparoscopic Technique

BACKGROUND

Hysterectomy is one of the most common procedures performed in the United States. New techniques utilizing laparoscopic and robotic technology are becoming increasingly common. It is unknown if these minimally invasive surgical techniques alter the risk of surgical site infections (SSI).

METHODS

We performed a retrospective review of all patients undergoing abdominal hysterectomy at our institution between January 2011 and June 2013. International Classification of Diseases, Ninth edition (ICD-9) codes and chart review were used to identify patients undergoing hysterectomy by open, laparoscopic, or robotic approach and to identify patients who developed SSI subsequently. Chi-square and analysis of variance (ANOVA) tests were used to identify univariate risk factors and logistic regression was used to perform multivariable analysis.

RESULTS

During this time period, 986 patients were identified who had undergone abdominal hysterectomy, with 433 receiving open technique (44%), 116 laparoscopic (12%), 407 robotic (41%), and 30 cases that were converted from minimally invasive to open (3%). Patients undergoing laparoscopic-assisted hysterectomy were significantly younger and had lower body mass index (BMI) and American Society of Anesthesiologists (ASA) scores than those undergoing open or robotic hysterectomy. There were no significant differences between patients undergoing open versus robotic hysterectomy. The post-operative hospital stay was significantly longer for open procedures compared with those using laparoscopic or robotic techniques (5.1, 1.7, and 1.6 d, respectively; p<0.0001). The overall rate of SSI after all hysterectomy procedures was 4.2%. More SSI occurred in open cases (6.5%) than laparoscopic (0%) or robotic (2.2%) (p<0.0001). Cases converted to open also had an increased rate of SSI (13.3%). In both univariate and multivariable analyses, open technique, wound class of III/IV, age greater than 75 y, and morbid obesity were all associated with increased risk of SSI.

CONCLUSION

Laparoscopic and robotic hysterectomies were associated with a significantly lower risk of SSI and shorter hospital stays. Body mass index, advanced age, and wound class were also independent risk factors for SSI.