Silver-coated modular Megaendoprostheses in salvage revision arthroplasty after periimplant infection with extensive bone loss - a pilot study of 34 patients

Are silver-coated megaprostheses superior to uncoated megaprostheses in managing chronic end-stage periprosthetic hip and knee infection?

INTRODUCTION

Outcomes for silver coated megaprostheses (SC-MP) used in cases of end-stage periprosthetic joint infection (PJI) have not been clearly defined. Although attractive, concerns over implant longevity and the risk of infection relapse exist among the scientific community. Therefore, we sought to investigate the effect of silver coating in lower-extremity MPs used in such difficult-to-treat scenarios. The study's primary hypothesis was that the periprosthetic infection control rate would be higher in patients with silver-coated implants.

MATERIALS AND METHODS

Non-interventional retrospective study with a historical comparison group. We identified all consecutive end-stage hip and knee PJI cases at our center managed with exchange arthroplasty using a silver-coated megaprosthesis from January 2016 to March 2021, these cases were compared with a historical cohort of end-stage PJI cases managed with uncoated megaprostheses. The main outcome studied was infection control rate. Secondarily, we analyzed the short-to-medium-term survivorship of this type of silver-coated implant.

RESULTS

Fifty-nine megaprostheses used in cases of end-stage PJI were included in this study. We identified 30 cases of chronic hip or knee PJI in which a silver-coated modular megaprosthesis was implanted. Our non-coated megaprosthesis (NC-MP) historical group included 29 patients. Both groups had similar demographic characteristics. We found no statistically significant differences in infection control rate (80% vs. 82.8%, p = 0.47) or implant survivorship (90% vs. 89.65%, p = 1) after a mean follow-up for SC-MP of 46.43 months, and 48 months for the non-coated MP group. In relapsed cases, there were no differences in infection eradication after DAIR (66% SC-MP vs. 60% NC-MP success rate, p = 1). During the follow-up we observed one case of skin argyria without further repercussion.

CONCLUSION

We were unable to confirm our initial hypothesis that use of silver-coated implants in end-stage PJI scenarios may be associated with better outcomes in terms of infection control or implant survivorship.

Use of a silver-coated plate to treat a postoperative infection after high tibial osteotomy - a case report

Unilateral osteoarthritis of the knee can be treated by osteotomy. In case of postoperative infection after high tibial osteotomy, treatment can be challenging and often requires implant removal with the risk of loss of reduction. In the presented case, a 47-year old patient suffered postoperative infection after high tibial osteotomy using an angular stable plate with the need for multiple revision surgeries and anti-infective therapy. Implant exchange to a silver-coated angular plate led to infection control with undisturbed wound healing and further bone consolidation. Full bone consolidation could be achieved radiographically 12 months after the last revision surgery. One-step implant exchange using silver-coated implants could be a promising approach to address postoperative infections after high tibial osteotomy.

Silver-Coated Distal Femur Megaprosthesis in Chronic Infections with Severe Bone Loss: A Multicentre Case Series

Periprosthetic joint infections (PJI) and fracture-related infections (FRI) of the distal femur (DF) may result in massive bone defects. Treatment options include articulated silver-coated (SC) megaprosthesis (MP) in the context of a two-stage protocol. However, there is limited evidence in the literature on this topic. A retrospective review of the prospectively maintained databases of three Institutions was performed. Forty-five patients were included. The mean follow-up time was 43 ± 17.1 months. Eight (17.8%) patients had a recurrent infection. The estimated recurrence-free survival rate was 91.1% (93.5% PJI vs. 85.7% FRI) 2 years following MP implantation, and 75.7% (83.2% PJI vs. 64.3% FRI; p = 0.253) after 5 years. No statistically relevant difference was found according to the initial diagnosis (PJI vs. FRI). Among possible risk factors, only resection length was found to significantly worsen the outcomes in terms of infection control (p = 0.031). A total of eight complications not related to infection were found after reimplantation, but only five of them required further surgery. Above-the-knee amputation was performed in two cases (4.4%), both for reinfection. Articulated DF SC MP in a two-stage protocol is a safe and effective treatment for chronic knee infection with severe bone loss.

Management of complications of mega-implants following treatment of primary and periprosthetic fractures of the lower extremities

In recent years, indications for implanting mega-implants were established in managing major bone defects linked to revision arthroplasty due to loosening, periprosthetic fractures, re-implantation following periprosthetic joint infection, non-union following fractures as well as complex intraarticular primary fractures. This study was conducted to discuss and analyze the strategy of diagnosis and management of complications following the use of mega-implants in treating primary and periprosthetic fractures of the lower extremities. This is a monocentric retrospective study. Patients aged ≥ 18 years who underwent implantation of a megaendoprosthesis due to periprosthetic or primary fractures of the lower extremity between January 2010 and February 2023 were identified from the authors' hospital information system. We identified 96 patients with equal numbers of fractures (71 periprosthetic fractures and 25 primary fractures). 90 cases out of 96 were investigated in this study. The drop-out rate was 6.25% (six cases). The average follow-up period was 22 months (1 to 8 years) with a minimum follow-up of 1 year. The diagnosis of complications was provided on the basis of subjective symptoms, clinical signs, radiological findings and laboratory investigations such as C-reactive protein, leucocyte count and the microbiological findings. The indications for implantations of modular mega-implants of the lower extremities were periprosthetic fractures (65 cases/72.22%) and primary fractures (25 cases/27.78%). Pathological fractures due to malignancy were encountered in 23 cases (25.56%), in one case due to primary tumor (1.11%) and 22 cases due to metastatic lesions (24.44%). Two cases (2.22%) presented with primary intraarticular fractures with severe osteoporosis and primary arthrosis. In all cases with malignancy staging was performed. Regarding localization, proximal femur replacement was encountered in 60 cases (66.67%), followed by distal femur replacement (28 cases/31.11%) and total femur replacement (2 cases/2.22%). The overall complication rate was 23.33% (21 complications in 21 patients). The most common complication was dislocation which was encountered in nine cases (10%), all following proximal femoral replacement (9 cases out of 60, making 15% of cases with proximal femoral replacement). The second most common complication was infection (six cases, 6.67%), followed by four aseptic loosenings (4.44%), further intraoperative periprosthetic fracture in one case (1.11%) and a broken implant in one case (1.11%). We noticed no cases with wear and tear of the polyethylene components and no cases of disconnections of the modular components. Mega-endoprostheses enable versatile management options in the treatment of primary and periprosthetic fractures of the lower extremities. The rate of complications such as loosening, implant failure, dislocation and infection are within an acceptable range in this preliminary analysis. However, implantation of mega-endoprostheses must be strictly indicated due the limited salvage options following surgery.

Megaprosthesis in Non-Oncologic Settings-A Systematic Review of the Literature

Modular megaprostheses (MPs) are commonly used after bone-tumor resection, but they can offer a limb salvage solution in massive bone defects. The aim of this systematic review of the Literature is to provide a comprehensive data collection concerning the use of MPs in non-oncologic cases, and to provide an overview of this topic, especially from an epidemiologic point of view. Three different databases (PubMed, Scopus, and Web of Science) were searched for relevant articles, and further references were obtained by cross-referencing. Sixty-nine studies met the inclusion criteria, reporting on cases of MP in non-oncologic cases. A total of 2598 MPs were retrieved. Among these, 1353 (52.1%) were distal femur MPs, 941 (36.2%) were proximal femur MPs, 29 (1.4%) were proximal tibia MPs and 259 (10.0%) were total femur MPs. Megaprostheses were most commonly used to treat periprosthetic fractures (1158 cases, 44.6%), in particular in the distal femur (859, 74.2%). Overall, complications were observed in 513 cases (19.7%). Type I (soft tissue failures) and type IV (infection) according to the Henderson classification were the most frequent (158 and 213, respectively). In conclusion, patients with severe post-traumatic deformities and/or significant bone loss who have had previous septic complications should be considered as oncologic patients, not because of the disease, but because of the limited therapeutic options available. The benefits of this treatment include relatively short operative times and immediate weight-bearing, thus making MP particularly attractive in the lower limb.

Staged Management of Infection with Adjustable Spacers After Megaprosthesis Implantation in Primary Sarcoma Patients

Background

While periprosthetic joint infection has always been a significant concern for orthopaedic surgeons, the rate of infection is five to ten times higher after tumor prosthesis implantation. With the growing use of mega-implants, the number of these infections has also increased. We aimed to investigate the results of our patients with a primary malignant musculoskeletal tumor, who underwent two-stage revision surgery for an infected mega-prosthesis. We also presented the emerging complicatons and required soft tissue reconstruction procedures.

Methods

The study included 32 primary bone and soft tissue sarcoma patients who underwent a two-stage revision procedure for infection. After a rigorous bone and soft tissue debridement procedure at the first stage, antibiotic-loaded bone cement was wrapped around a cloverleaf type intramedullary nail and inserted into the forming gap. After a minimum of 6 weeks of antibiotic therapy, depending on patients' clinical signs and serum infection markers, the reimplantation stage was undertaken.

Results

The mean oncologic follow-up period was 28 months (range 5-96 months). During this period, 11 patients died because of non-infection related causes, 12 patients were alive with their disease, whereas 9 patients were totally free of their oncologic condition. The infection was eradicated in all survivors except one patient, where a high-level transfemoral amputation became necessary.

Conclusion

Periprosthetic infection after tumor proshesis implantation in cancer patients can be managed with same principles as conventional arthroplaty procedures, taking care that they are immunocompromised and vulnerable patients and their bone stock loss is significant which makes surgical options more challenging.

Knee Arthrodesis with a Modular Silver-Coated Endoprosthesis for Infected Total Knee Arthroplasty with Extensive Bone Loss: A Retrospective Case-Series Study

INTRODUCTION

Knee arthrodesis is a limb salvage intervention for persistent periprosthetic joint infection (PJI) when revision total knee arthroplasty fails. Conventional arthrodesis techniques are associated with the increased rate of complications, especially in patients with extensive bone loss and extensor tendon deficiency.

METHODS

Eight patients with a modular silver-coated arthrodesis implant after failed exchange arthroplasty for infection, were retrospectively reviewed. All patients had significant bone loss, while 5 displayed extensor tendon deficiency. Survivorship, complications, leg length discrepancy, median Visual Analogue Scale (VAS) and Oxford Knee score (OKS) were evaluated.

RESULTS

The median follow up was 32 months (range 24-59 months). The survivorship rate of the prosthesis was 86% during the minimum time of follow up of 24 months. In one patient recurrence of the infection was observed and above-knee amputation was performed. The median postoperative leg length discrepancy was 2.07 ± 0.67 cm. Patients were able to ambulate with mild or no pain. The median VAS and OKS was 2.14 ± 0.9 and 34.7 ± 9.3, respectively.

CONCLUSIONS

The results of our study demonstrated that knee arthrodesis with a silver coated arthrodesis implant, performed for persistent PJI in patients with significant bone loss and extensor tendon deficit, provided a stable construct, allowed eradication of infection and was associated with good functional outcome.

Potential side effects of antibacterial coatings in orthopaedic implants: A systematic review of clinical studies

Objective: The systematic review aimed to determine the potential side effects of antibacterial coatings in orthopaedic implants. Methods: Publications were searched in the databases of Embase, PubMed, Web of Science and Cochrane Library using predetermined keywords up to 31 October 2022. Clinical studies reporting side effects of the surface or coating materials were included. Results: A total of 23 studies (20 cohort studies and three case reports) reporting the concerns about the side effects of antibacterial coatings were identified. Three types of coating materials, silver, iodine and gentamicin were included. All of studies raised the concerns regarding safety of antibacterial coatings, and the occurrence of adverse events was observed in seven studies. The main side effect of silver coatings was the development of argyria. For iodine coatings, only one anaphylactic case was reported as an adverse event. No systemic or other general side effects were reported for gentamicin. Conclusion: Clinical studies on the side effects of antibacterial coatings were limited. Based on the available outcomes, the most reported side effects of antibacterial coatings in clinical use were argyria with silver coatings. However, researchers should always pay attention to the potential side effects of antibacterial materials, such as systematic or local toxicity and allergy.

Prosthetic Joint Infection in Mega-Arthroplasty Following Shoulder, Hip and Knee Malignancy-A Prospective Follow-Up Study

INTRODUCTION

The risk of prosthetic joint infection (PJI) in mega-prosthesis for malignancy is increased compared with non-tumor cases. While several studies describe PJI in tumor-related arthroplasty, prospective studies comparing infection characteristics among different joints are limited. The present study analyzes mega-arthroplasty for hip, knee, and shoulder malignancy and compares the epidemiology, diagnosis, microbe spectrum, treatments, and outcomes between the different entities.

METHODS

The retrospective inclusion criteria were as follows: (1) mega-arthroplasty (2) in the hip, knee, or shoulder joint and a total femur arthroplasty (3) following a malignant bone tumor or metastasis (4) between 1996 and 2019. All included patients were prospectively followed and invited for a renewed hospital examination, and their PJI characteristics (if identified) were analyzed using both retrospective as well as newly gained prospective data. A PJI was defined according to the Infectious Disease Society of America (IDSA) and re-infection was defined according to the modified Delphi Consensus criteria.

RESULTS

In total, 83 cases of tumor mega-arthroplasty at a mean follow-up of 3.9 years could be included (32 knee, 30 hip, and 19 shoulder cases and 2 cases of total femur arthroplasty). In total, 14 PJIs were identified, with chondrosarcoma in 6 and osteosarcoma in 3 being the leading tumor entities. Knee arthroplasty demonstrated a significantly higher rate of PJI (p = 0.027) compared with hips (28.1% vs. 6.7%), while no significant difference could be found between the knee and shoulder (10.5%) (p = 0.134) or among shoulder and hip cases (p = 0.631). The average time of PJI following primary implantation was 141.4 months in knee patients, 64.6 in hip patients, and 8.2 months in shoulder patients. Age at the time of the primary PJI, as well as the time of the first PJI, did not show significant differences among the groups. Thirteen of the fourteen patients with PJI had a primary bone tumor. Statistical analysis showed a significant difference in the disadvantage of primary bone tumors (p = 0.11). While the overall cancer-related mortality in the knee PJI group (10%) was low, it was 50% in the hip and 100% in the shoulder group.

CONCLUSION

The risk of PJI in knee tumor arthroplasty is significantly increased compared with hips, while cancer-related mortality is significantly higher in hip PJI cases. At the same time, mega-prostheses appear to be associated with a higher risk of infection due to a primary bone tumor compared with metastases. The study confirms existing knowledge concerning PJI in tumor arthroplasty, while, being one of the few studies to compare three different joints concerning PJI characteristics.

Implant surface modifications as a prevention method for periprosthetic joint infection caused by Staphylococcus aureus: a systematic review and meta-analysis

Abstract. Background: Periprosthetic joint infection is the most common infection due to joint replacement. It has been reported that, over a 5-year time span, 3.7 % of cases occurred annually. This statistic has increased to 6.86 % over 16 years. Thus, an effective method is required to reduce these complications. Several strategies such as coating methods with various materials, such as antibiotics, silver, and iodine, have been reported. However, the best preventive strategy is still undetermined. Therefore, this systematic review aims to evaluate the outcome of coating methods on joint arthroplasty as a treatment or preventive management for infection complications. Methods: Eligible articles were systematically searched from multiple electronic databases (PubMed, Cochrane library, and ScienceDirect) up to 2 June 2022. Based on the criterion inclusion, eight articles were selected for this study. The Newcastle–Ottawa scale (NOS) was used to assess the quality of the study, and the meta-analysis test was conducted with Review Manager 5.4. Results: The quality of the articles in this study is in the range of moderate to good. It was found that the application of modified antibiotic coatings significantly reduced the occurrence of periprosthetic joint infection (PJI) (p 0.03), and silver coating could not significantly (p 0.47) prevent the occurrence of PJI. However, according to the whole aspect of coating modification, the use of antibiotics, silver, and iodine can minimize the occurrence of PJI (p <0.0001). Conclusion: Coating methods using antibiotics are an effective method that could significantly prevent the occurrence of PJI. On the other hand, coating with non-antibiotic materials such as silver could not significantly prevent the incidence of PJI.

Long-term changes in serum silver concentrations after extremity reconstruction with silver-coated megaprostheses

Silver-coated megaprostheses are considered to reduce infection rate following reconstruction of bone defects in tumour surgery or revision arthroplasty. However, little is known about systemic silver exposure and possible side effects. The aim of this study was to analyse serum silver concentrations in patients with silver-coated megaprostheses over a prolonged time period. Between 2004 and 2016, 46 patients (52.2% female, mean age at surgery 47.1 ± 24.2 years) received silver-coated megaprostheses for septic (n = 26) or oncological (n = 17; main implant since 2013) indications, or aseptic loosening (n = 3). Blood was drawn from all patients within the first few days following surgery (without silver ion levels) and thereafter every 6 months at the outpatient department (with silver ion levels). Inductively coupled plasma mass spectrometry was used to determine silver ion levels. Median follow-up was 47.3 months (IQR: 16.1–78.9). Overall, 29 revision surgeries became necessary in 20 patients, equivalent to a cumulative complication rate of 63.0%. Revisions were most commonly for periprosthetic joint infections (PJIs, n = 12) and instability/soft tissue problems (n = 10). Revision-free implant survival was 81.4%, 42.3% and 35.2% at one, 5 and 10 years. Incidence of local argyria was 8.7% (n = 4). Silver ion levels at two or more consecutive time points during follow-up were available for 26 patients. An increment of silver levels within the first months (“run-in”) was observed, followed by an unspecific undulating course. Median initial and latest follow-up (median, 49.5 months) serum silver ion levels were 16.0 ppb (IQR: 9.1–29.1) and 7.4 ppb (IQR: 2.7–14.1), respectively. According to the multivariate mixed linear random-effects model, development of PJI was associated with significantly higher silver ion levels over time (p = 0.002), irrespective of time from surgery (p = 0.274). In the current series, a cumulative complication rate of 63.0% was observed for patients receiving silver-coated megaprostheses for septic of oncological indications. An overall unspecific course of silver ion concentration was present. Development of PJI was significantly associated with increased silver ion levels over time. Yet, no systemic complication associated to high silver levels occurred. It can be concluded that silver-coated implants constitute a safe solution for megaprosthetic reconstruction, but monitoring of silver concentrations is recommended.

The Performances of Conventional Titanium and Silver-Coated Megaprostheses in Non-oncological and Post-oncological Patients: An Analysis of Infection Failures in 142 Patients

BACKGROUND

Megaprostheses are one of the preferred choices of reconstruction after tumor resection. Periprosthetic joint infections are one of the most serious complications of joint prostheses surgeries. In this study, our aim was to analyze the efficacy of silver-coated megaprostheses in reducing the risk of prosthesis-related infection.

METHODS

One hundred forty-two patients who had undergone implantation of a mega-endoprosthesis for non-neoplastic or post-neoplastic conditions were included in this retrospective study. The end-point of the survival analysis was the prosthesis failure due to infection.

RESULTS

Thirty-eight patients had undergone implantation of a silver-coated megaprosthesis and 104 patients a megaprosthesis without silver coating. The survival analysis showed an overall infection-free survival rate of 82.3% at five years and 61.9% at 10 years. Silver-coated prostheses had an HR of 0.72 (95% CI: 0.26-2.05; P=0.54).

CONCLUSION

Implantation of a silver-coated mega-prosthesis in non-oncological patients did not significantly reduce the risk of prosthesis-related infection.

Environmental, Microbiological, and Immunological Features of Bacterial Biofilms Associated with Implanted Medical Devices

The spread of biofilms on medical implants represents one of the principal triggers of persistent and chronic infections in clinical settings, and it has been the subject of many studies in the past few years, with most of them focused on prosthetic joint infections. We review here recent works on biofilm formation and microbial colonization on a large variety of indwelling devices, ranging from heart valves and pacemakers to urological and breast implants and from biliary stents and endoscopic tubes to contact lenses and neurosurgical implants. We focus on bacterial abundance and distribution across different devices and body sites and on the role of environmental features, such as the presence of fluid flow and properties of the implant surface, as well as on the interplay between bacterial colonization and the response of the human immune system.

Development of Silver-Containing Hydroxyapatite-Coated Antimicrobial Implants for Orthopaedic and Spinal Surgery

The prevention of surgical site infections is directly related to the minimization of surgical invasiveness, and is in line with the concept of minimally invasive spine therapy (MIST). In recent years, the incidence of postoperative infections has been increasing due to the increased use of spinal implant surgery in patients at high risk of infection, including the elderly and easily infected hosts, the limitations of poor bone marrow transfer of antibiotics, and the potential for contamination of surgical gloves and instruments. Thus, the development of antimicrobial implants in orthopedic and spinal surgery is becoming more and more popular, and implants with proven antimicrobial, safety, and osteoconductive properties (i.e., silver, iodine, antibiotics) in vitro, in vivo, and in clinical trials have become available for clinical use. We have developed silver-containing hydroxyapatite (Ag-HA)-coated implants to prevent post-operative infection, and increase bone fusion capacity, and have successfully commercialized antibacterial implants for hip prostheses and spinal interbody cages. This narrative review overviews the present status of available surface coating technologies and materials; describes how the antimicrobial, safety, and biocompatibility (osteoconductivity) of Ag-HA-coated implants have been demonstrated for commercialization; and reviews the clinical use of antimicrobial implants in orthopedic and spinal surgery, including Ag-HA-coated implants that we have developed.

Megaprosthesis anti-bacterial coatings: A comprehensive translational review

Periprosthetic joint infections (PJI) are catastrophic complications for patients with implanted megaprostheses and pose significant challenges in the management of orthopaedic oncology patients. Despite various preventative strategies, with the increasing rate of implanted orthopaedic prostheses, the number of PJIs may be increasing. PJIs are associated with a high rate of amputation. Therefore, novel strategies to combat bacterial colonization and biofilm formation are required. A promising strategy is the utilization of anti-bacterial coatings on megaprosthetic implants. In this translational review, a brief overview of the mechanism of bacterial colonization of implants and biofilm formation will be provided, followed by a discussion and classification of major anti-bacterial coatings currently in use and development. In addition, current in vitro outcomes, clinical significance, economic importance, evolutionary perspectives, and future directions of anti-bacterial coatings will also be discussed. Megaprosthetic anti-bacterial coating strategies will help reduce infection rates following the implantation of megaprostheses and would positively impact sarcoma care. STATEMENT OF SIGNIFICANCE: This review highlights the clinical challenges and a multitude of potential solutions to combating peri-prosthetic join infections in megaprotheses using anti-bacterial coatings. Reducing infection rates following the implantation of megaprostheses would have a major impact on sarcoma care and major trauma surgeries that require reconstruction of large skeletal defects.

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.

Biomaterials and technologies in the management of periprosthetic infection after total hip arthroplasty: An updated review

Although total hip arthroplasty (THA) is considered one of the most efficacious procedures for managing various hip conditions, failures due to different mechanisms are still being reported. Periprosthetic joint infection (PJI) is one of the devastating causes of failure and revision of THA. PJI carries a burden on the patient, the surgeon, and the health-care system. The diagnosis and management of PJIs carry many morbidities and increased treatment costs. The development of PJI is multifactorial, including issues related to the patient’s general condition, the surgeon’s efficiency, surgical technique, and the implants used. Recent advances in the area of diagnosis and predicting PJI as well as introducing new technologies and biomaterials update for the prevention and treatment of PJI. Local implant coatings, advancement in the bearing surfaces technologies, and new technologies such as immunotherapy and bacteriophage therapy were introduced and suggested as contemporary PJI eradication solutions. In this review, we aimed at discussing some of the newly introduced materials and technologies for the sake of PJI control.

Individual Revision Knee Arthroplasty Is a Safe Limb Salvage Procedure

Introduction: Revision total knee arthroplasty after multiple pre-surgeries is challenging. Due to severe bone defects, standard implants for metaphyseal and diaphyseal anchoring may no longer be suitable. The primary aim of this case series is to evaluate the early complication rate for individual knee implants with custom-made cones and stems after two-stage revision with severe bone defects. Methods: Ten patients who were treated with custom-made 3D-printed knee revision implants were included. Inclusion criteria were a two-stage revision due to late-onset or chronic periprosthetic joint infection as well as aseptic loosening. All severe bone defects were AORI type III. All procedure-related complications were evaluated. Postoperative range of motion after one year was measured. The time between the two surgeries was evaluated. Results: The mean follow-up was 21 months (range: 12–40). The mean time between the two-stage surgeries was 71.6 days. No fractures were observed intra- and postoperatively. Two patients were revised without changing metal components due to persistent hematoma (three weeks post-surgery) and persistent PJI (three months post-surgery). The mean passive postoperative range of motion was 92° (range: 80–110°). Conclusions: Individual custom-made implants for rTKA provide a safe procedure for patients with huge bone defects after several pre-surgeries. If standard knee systems with standard cones or sleeves are not suitable anymore, custom-made treatment offers the patient the last option for limb preservation. However, this is associated with increased costs.

The role of silver coating for arthroplasty components

Periprosthetic joint infection (PJI) is one of the most dreaded complications after arthroplasty surgery; thus numerous approaches have been undertaken to equip metal surfaces with antibacterial properties. Due to its antimicrobial effects, silver is a promising coating for metallic surfaces, and several types of silver-coated arthroplasty implants are in clinical use today. However, silver can also exert toxic effects on eukaryotic cells both in the immediate vicinity of the coated implants and systemically. In most clinically-used implants, silver coatings are applied on bulk components that are not in direct contact with bone, such as in partial or total long bone arthroplasties used in tumour or complex revision surgery. These implants differ considerably in the coating method, total silver content, and silver release rates. Safety issues, such as the occurrence of argyria, have been a cause for concern, and the efficacy of silver coatings in terms of preventing PJI is also controversial. The application of silver coatings is uncommon on parts of implants intended for cementless fixation in host bone, but this option might be highly desirable since the modification of implant surfaces in order to improve osteoconductivity can also increase bacterial adhesion. Therefore, an optimal silver content that inhibits bacterial colonization while maintaining osteoconductivity is crucial if silver were to be applied as a coating on parts intended for bone contact. This review summarizes the different methods used to apply silver coatings to arthroplasty components, with a focus on the amount and duration of silver release from the different coatings; the available experience with silver-coated implants that are in clinical use today; and future strategies to balance the effects of silver on bacteria and eukaryotic cells, and to develop silver-coated titanium components suitable for bone ingrowth. Cite this article: Bone Joint J 2021;103-B(3):423-429.

Antibacterial hydrogel coating in joint mega-prosthesis: results of a comparative series

PURPOSE

Joint mega-prosthesis after bone tumors, severe trauma or infection is associated with high rates of post-surgical septic complications. A fast-resorbable antibacterial hydrogel coating (DAC®, Defensive Antibacterial Coating) has previously been shown to be able to significantly reduce surgical site infection in various clinical settings. Aim of the present study was to evaluate the safety and efficacy of the DAC hydrogel coating to prevent early periprosthetic joint infection after joint mega-prosthesis.

METHODS

In this three-centers, case-control study, 43 patients, treated with an antibacterial hydrogel coated mega-prosthesis for oncological (N = 39) or non-oncological conditions (N = 4), were retrospectively compared with 43 matched controls, treated with mega-implants without the coating. Clinical, laboratory and radiographic examinations were performed to evaluate the occurrence of post-surgical infection, complications and adverse events.

RESULTS

At a mean follow-up of 2 years, no evidence of infection or adverse events were observed in the DAC-treated group, compared to six cases of post-surgical infection in the control group.

CONCLUSION

This matched case-control study shows that a fast-resorbable, antibiotic-loaded coating can be safely used to protect joint mega-prosthesis, providing a reduction of early surgical site infections with no side effects. Larger prospective trials with longer follow-ups are warranted to confirm this report.

TRIAL REGISTRATION

RS1229/19 (Regina Elena National Cancer Institute Experimental Registry Number).

Management of Modular Mega-Implant Infection of the Lower Extremity

INTRODUCTION

Revision arthroplasty involving mega-implants is associated with a high complication rate. In particular, infection is a serious complication of revision arthroplasty of hip and knee joints and has been reported to have an average rate of 18%, and for mega-implants, the range is from 3 to 36%. This study was designed to analyze the strategy of treatment of infection of mega-endoprostheses of the lower extremities in our patient cohort, particularly the management of chronic infection.

MATERIAL AND METHODS

This was a retrospective study that focused on the results of the treatment of periprosthetic infections of mega-implants of the lower extremities. We identified 26 cases with periprosthetic infections out of 212 patients with 220 modular mega-endoprostheses of the lower extremities who were treated in our department between September 2013 and September 2019. As a reinfection or recurrence, we defined clinical and microbiological recurrences of local periprosthetic joint infections after an antibiotic-free period.

RESULTS

In this study, 200 cases out of 220 were investigated. The average follow-up period was approximately 18 months (6 months to 6 years). Endoprosthesis infections after implantation of mega-implants occurred in 26 cases (13%). This group comprised 2 early infections (within the first 4 weeks) and 24 chronic infections (between 10 weeks and 6 years after implantation). Nineteen cases out of the identified 26 cases with infection (73.1%) belong to the group of patients who were operated on due to major bone loss following explantation of endoprosthetic components due to previous periprosthetic joint infection. The remaining seven cases with infection comprised four cases following management of periprosthetic fracture, two cases following treatment of aseptic loosening, and one case following tumor resection. All infections were treated surgically. In all cases, the duration of continuous antibiotic treatment did not exceed 6 weeks. Both cases with early infection were treated by exchanging polyethylene inlays and performing debridement with lavage (two cases). In two (7.7%) cases with chronic infection, one-stage surgery was performed. In all remaining cases with chronic infection (22 cases; 84.6%), explantation of all components and temporary implantation of cement spacers were carried out prior to reimplantation.

CONCLUSION

There is still no gold standard therapeutic regimen for the management of periprosthetic infection of mega-implants, though radical surgical debridement and lavage accompanied by systemic antibiotic therapy are the most important therapeutic tools in all cases of periprosthetic infections, regardless of the time of onset. Further studies are needed to standardize management strategies of such infections. Nevertheless, it is not uncommon for compromises to be made based on the particular condition of the individual.

Interaction of Differently Coated Silver Nanoparticles With Skin and Oral Mucosal Cells

Silver nanoparticles (AgNP) can be found in different consumer products and various medical devices due to their excellent biocidal properties. Despite extensive scientific literature reporting biological effects of AgNP, there is still a lack of scientific evidence on how different surface functionalization affects AgNP interaction with the human skin and the oral epithelium. This study aimed to investigate biological consequences following the treatment of HaCaT and TR146 cells with AgNP stabilized with negatively charged sodium bis(2-ethylhexyl)-sulfosuccinate (AOT), neutral polyvinylpyrrolidone (PVP), and positively charged poly-l-lysine (PLL). All AgNP were characterized by means of size, shape and surface charge. Interactions with biological barriers were investigated in vitro by determining cell viability, particle uptake, oxidative stress response and DNA damages following AgNP treatment. Results showed a significant difference in cytotoxicity depending on the surface coating used for AgNP stabilization. All three types of AgNP induced apoptosis, oxidative stress response and DNA damages in cells, but AOT- and PVP-coated AgNP exhibited lower toxicity than positively charged PLL-AgNP. Considering the number of data gaps related to the safe use of nanomaterials in biomedicine, this study highlights the importance of particle surface functionalization that should be considered during design and development of future AgNP-based medical products.

Transglutaminase Cross-Linked Gelatin-Alginate-Antibacterial Hydrogel as the Drug Delivery-Coatings for Implant-Related Infections

Implant-related infection may be catastrophic and result in poor functional outcome, chronic osteomyelitis, implant failure or even sepsis and death. Based on a transglutaminase (TGase) cross-linked/antibiotics-encapsulated gelatin-alginate hydrogel, the main aim of this study is to establish an effective antibiotic slow-release system. The second aim is to evaluate the efficacy of a hydrogel-encapsulated antibiotic-containing titanium pin in preventing implant-related infections in a rat model. The prepared gelatin/alginate/gentamicin or vancomycin hydrogel was covalently cross-linked with transglutaminase (TGase). Its drug release profile and cytotoxicity were determined and the Wistar rat animal model was performed to validate its efficacy by radiographic examination, Micro-CT (computed tomography) evaluation and histo-morphological analysis at 12 weeks after surgery. When gelatin and alginate were thoroughly mixed with TGase, both 0.5% and 1.0% TGase can effectively cross link the hydrogel; the release of antibiotic is slowed down with higher degree of TGase concentration (from 20 min to more than 120 h). In the animal study, antibiotic-impregnated hydrogel is effective in alleviating the implant-related infections. Relative to that of a positive control group, the experimental group (vancomycin treatment group) showed significant higher bone volume, more intact bony structure with only mild inflammatory cell infiltration. This newly designed hydrogel can effectively deliver antibiotics to reduce bacterial colonization and biofilm formation on the implant surface. The remaining challenges will be to confer different potent antibacterial medications with good biocompatibility and fulfill the safety, practical and economic criteria for future clinical translation.

An Evolution of Shoulder Periprosthetic Infections Management: MicroDTTect, Bioactive Glass and Tantalum Cones Employment

Periprosthetic joint infections of the shoulder (PJIS) are the major cause for revision within the first two post-operative years, and are challenging both to diagnose and treat. Success depends on early identification of microorganisms, appropriate surgical procedures and efficient antibiotic administration. The peculiar microbiology of the shoulder may render the criteria for hip/knee PJI management inappropriate. In addition, later cases with clinically subtle signs often present diagnostic challenges. In recent years, specific issues of PJIS have been managed through the use of new instruments, such as MicroDTTect in pathogen detection and Bioactive Glass and tantalum cones in humeral bone loss. In the literature to date, no reports have been found that discuss the application in shoulder revisions and infections. The early identification of the microorganisms that cause infection may help improve both treatment strategies and the efficacy of therapy. MicroDTTect proved to be more efficient than swab collection for bacterial identification in orthopedic surgery, thus reducing analysis costs. The increasing number of shoulder arthroplasties is associated with an increase in the number of revisions. In cases of massive metaphyseal humeral bone loss, several techniques have been described; no reports have been reported regarding tantalum in humeral bone loss management. In some cases the tantalum cones required adaptation for femoral diaphysis in the augmentation of the humerus metaphysis and bone loss management improvement. Obtaining stable osseointegration of prosthetic implants is one of the greatest issues in orthopedic surgery, and even more crucial in revisions. Bioactive glasses demonstrated good regenerative and osseointegration properties, and an excellent candidate as a bone graft, scaffold and antibiotics deliverer. The Bioactive glasses were used to increase prosthesis-bone interface stability and fill bone defects in PJIS revision surgeries, contributing to the prevention of re-infection. Longer-term follow-up will be necessary to determine if construction durability is improved in the long term.

Toward Antibacterial Coatings for Personalized Implants

The complex reconstructive surgeries for which patient-specific orthopedic, maxillofacial, or dental implants are used often necessitate wounds that are open for a considerable amount of time. Unsurprisingly, this allows bacteria to establish implant-associated infection, despite the scrupulous sterilization efforts made during surgery. Here, we developed a prophylactic bactericidal coating via electrophoretic deposition technology for two 3D-printed porous titanium implant designs. The surface characteristics, antibiotic release behavior, antibacterial properties, and impact on osteoblast cell proliferation of the optimized coatings were investigated. The results unequivocally confirmed the biofunctionality of the implants in vitro. This study reveals a new avenue for future antibacterial patient-specific implants.

Silver-coated megaprosthesis in prevention and treatment of peri-prosthetic infections: a systematic review and meta-analysis about efficacy and toxicity in primary and revision surgery

AIM

Prosthetic joint infection (PJI) is a common complication following orthopedic megaprosthetic implantations (EPR), estimated up to 50%. Silver coatings were introduced in order to reduce the incidence of PJI, by using the antibacterial activity of silver. Three different silver coatings are available: MUTARS^® (Implantcast), Agluna^® (Accentus Medical), PorAg^® (Waldemar Link). The aim of this review is to provide an overview on efficacy and safety of silver-coated EPR both in primary and revision surgery, comparing infection rate according to the type of implant.

METHODS

Through an electronic systematic search, we reviewed the articles concerning silver-coated EPRs. Infection rate, silver-related complications, local and blood concentrations of the silver were evaluated. Meta-analyses were performed to compare results from each study included.

RESULTS

Nineteen studies were included. The overall infection rate in patients with silver-coated implants was 17.6% (133/755). Overall infection rate in primary silver-coated EPR was been 9.2% (44/445), compared to 11.2% (57/507) of non-silver-coated implants. The overall infection rate after revisions was 13.7% (25/183) in patients with silver-coated EPR and 29.2% (47/161) when uncoated EPR were used, revealing a strength statistically significative utility of silver coatings in preventing infections in this group (p: 0.019). Generally, the use of MUTARS^® EPR had produced an almost constant decrease in the incidence of primary PJI but there are few data on the effectiveness in revisions. The results from the use of Agluna^® in both primary and revisions implants are inconstant. Conversely, PorAg^® had proven to be effective both in PJI prevention but, especially, when used in PJI revision settings. Local argyria was reported in 8 out of 357 patients (2.2%), while no systemic complications were described. Local and blood concentrations of silver were always reported very far to the threshold of toxicity, with the lowest concentration found using PorAg^®.

CONCLUSIONS

Silver-coated EPRs are safe and effective in reduction in PJI and re-infection rate, in particular when used in higher risk patients and after two-stage revisions to fight PJI.

Defensive antibacterial coating in revision total hip arthroplasty: new concept and early experience

BACKGROUND

Infections remains the most feared complication in total hip arthroplasty (THA). New strategies of PJI prevention includes coating of conventional implants. Defensive Antibacterial Coating (DAC), an antibacterial hydrogel coating made of hyaluronan, poly-D and L-lactide can protect biomaterials as an effective barrier at the time of implantation. In addition, it can be used with topical antibiotics to prevent early colonisation of the implant.

SCOPE

This manuscript describes the detailed function of the DAC in general as well as an analysis of its use in revision THA in a series of 28 patients in a short-term follow-up.Its use in patients undergoing cementless re-implantation after 2-staged procedures in THA is described in detail within the manuscript.

CONCLUSION

DAC found to be effective in terms of infection control and safety in our patient cohort and has been expanded for cementless 1-staged revisions in PJI of the hip in our institution.

Prevention of Prosthetic Joint Infection: From Traditional Approaches towards Quality Improvement and Data Mining

A projected increased use of total joint arthroplasties will naturally result in a related increase in the number of prosthetic joint infections (PJIs). Suppression of the local peri-implant immune response counters efforts to eradicate bacteria, allowing the formation of biofilms and compromising preventive measures taken in the operating room. For these reasons, the prevention of PJI should focus concurrently on the following targets: (i) identifying at-risk patients; (ii) reducing “bacterial load” perioperatively; (iii) creating an antibacterial/antibiofilm environment at the site of surgery; and (iv) stimulating the local immune response. Despite considerable recent progress made in experimental and clinical research, a large discrepancy persists between proposed and clinically implemented preventative strategies. The ultimate anti-infective strategy lies in an optimal combination of all preventative approaches into a single “clinical pack”, applied rigorously in all settings involving prosthetic joint implantation. In addition, “anti-infective” implants might be a choice in patients who have an increased risk for PJI. However, further progress in the prevention of PJI is not imaginable without a close commitment to using quality improvement tools in combination with continual data mining, reflecting the efficacy of the preventative strategy in a particular clinical setting.

Silver-coated (PorAg®) endoprosthesis can be protective against reinfection in the treatment of tumor prostheses infection

INTRODUCTION

We aim to evaluate the use of silver (PorAg^®) coated compared to uncoated prosthesis in two-stage revision for prosthetic joint infection (PJI) of distal femur and proximal tibia megaprosthesis in oncological patients.

MATERIALS AND METHODS

In total, 68 patients were retrospectively evaluated. Median age was 30 years (range 14-83). In total, 29 patients were re-implanted with PorAg^® prosthesis and 39 with uncoated prosthesis (Megasystem C^®, Waldemar Link GmbH & Co. KG, Hamburg, Germany). All patients had PJI confirmed according to Musculoskeletal Infection Society (MSIS) criteria. In 10 cases, no microorganism was identified at the time of first-stage revision, but all had a sinus communicating with the prosthesis. Successful eradication of the infection was defined by the absence of clinical/serologic evidence of infection at 6 months after the second stage or at latest follow-up. Infection was again defined according to the MSIS criteria.

RESULTS

At 3-year follow-up, estimated reinfection rate in the silver group was slightly lower than in uncoated EPR (10.3% vs. 17.5%, p = 0.104). Among reinfected patients, only one out of three patients (33%) in the silver group required an amputation compared to 80% in the nonsilver group (p = 0.047).

CONCLUSIONS

Our results show the efficacy of PorAg^® coating in the two-stage revision of knee EPR. PorAg^®-coated EPR may have possible advantages over this traditional strategy, in particular when applied to patients with a higher risk of reinfection.

Prevention of infection in open fractures: Where are the pendulums now?

Soft tissue management and fracture fixation including initial external fixation in Gustilo-Anderson type II and type III open fractures are cornerstones in the treatment but details on timing and type of wound closure, irrigation and debridement, systemic and local antibiotics, antimicrobial-coated implants and the use of Bone Morphogenetic Protein-2 remain controversial. This article looks at current clinical evidence of these items for the management of open fractures. Timing of debridement and wound closure remains critical. Early debridement by an experienced team within 24 h seems adequate while gross contamination, a devascularized limb, a multi-injured patient and compartment syndrome require immediate surgical intervention. Wound closure during the first surgery was shown to result in reduced rates for infections and nonunion. If soft-tissue reconstruction is needed, it should be performed within the first 7 days. Regarding types of irrigation fluid, antiseptic and antibacterial solutions did not prove to be superior to saline. High pressure irrigation has not been demonstrated to be beneficial whereas antibiotic administration as soon as possible has been proven to be favorable. Administration of more than 72 h was not superior to shorter systemic antibiotic intervals. For Gustilo-Anderson type I and II, broad spectrum antibiotic therapy is reasonable. Additional aminoglycosides for broader coverage are recommended in Gustilo-Anderson type III fractures. There is newer literature on the beneficial effects of the use of local antibiotics, e.g. by antibiotic beads. Coating of internal fixation devices is a modern approach to improve infection prophylaxis and gentamicin-coated implants have been demonstrated to be safe in clinical application. Vacuum assisted closure (VAC) could not evidence negative pressure wound therapy to reduce infection risk, improve self-rated disability or quality of life in open fractures, however, enhance treatment costs. Recombinant human bone morphogenetic proteins (rhBMP)-2 showed promising data in Gustilo-Anderson type III open tibial shaft fractures with lower rates of invasive secondary procedures. In conclusion, there is evidence for thorough debridement and irrigation with saline, early soft tissue coverage and the use of systemic and local antibiotics. Except for a short-term soft tissue coverage VAC seems not to be beneficial and rhBMP-2 is an additional tool in Gustilo-Anderson type III open fractures.

Antibiotic-laden cement wrap: A simple but effective way of treating patients with megaprosthesis infection

Infection is one of the commonest causes for megaprosthesis failure. The current treatment includes antibiotics but no surgery, debridement, prosthesis removal and joint fusion, prosthesis revision or amputation. Success in controlling infection may be less than 50% in implant revision. The overall risk of amputation is more than 20%. We believe that repeated debridement with antibiotic-laden cement wrap (ALCW) may be a reliable alternative for managing the megaprosthesis infection. The purposes of this article are to identify whether ALCW is an effective way of eradicating the megaprosthesis infection, the associated complications and the functional outcome after management by ALCW.

METHODS

This was a retrospective study of patients with megaprosthesis infection. From January 2014 to June 2016, there were five patients with tumour megaprosthesis infection who had undergone the ALCW procedure. Ages ranged from 17 to 59 years of age. Male to female ratio was 4:1. The patients studied had humeral (1), proximal femoral (1), distal femoral (1) and proximal tibial (2) prostheses. All patients had follow-ups more than 1 year (21-52 months) after treatment.

RESULTS

All patients recovered from their implant infection and the implants were retained in all patients. There was no sign of infection in the most recent follow-up. One patient died of osteosarcoma recurrence. One patient had a large block of cement causing plastic insert dislodgement in the shoulder joint 1 year after surgery. Another patient with a dislocated hip cup had revision carried out in the final debridement. The most recent Musculoskeletal Tumor society (MSTS) scores ranged from 21 to 30. All patients were satisfied with their treatment.

CONCLUSIONS

In this preliminary report of a small number of patients, ALCW has achieved 100% infection control. ALCW may be an easy and effective alternative for managing the megasprosthesis infection. The complications associated can be avoidable. The functional outcome is excellent.

Antimicrobial silver-coating for locking plates shows uneventful osteotomy healing and good biocompatibility results of an experimental study in rabbits

Infections after internal fixation of fractures remain a challenge. Silver is known for its antimicrobial activity, including activity against multi-resistant strains. The aim of the current study was to analyze the biocompatibility and potential influence on the osteotomy healing process of a silver-coating technology for locking plates compared to silver-free locking plates in an established rabbit model. The implants used in this study were 7-hole titanium locking plates, and plasma electrolytic oxidation (PEO) silver-coated equivalents. A total of 24 rabbits were used in this study (12 coated, 12 non-coated). An osteotomy of the midshaft of the humerus was created and the humerus stabilized with the 7-hole locking plates with a total of 6 screws. Radiographs were taken on day 0, week 2, 4, 6, 8, and 10 for continuous radiographical evaluation. All animals were euthanized after 10 weeks and further assessment was performed using X-rays, micro-CT, non-destructive four-point bending biomechanical testing and semi-quantitative histopathological evaluation. Furthermore, silver concentration was measured in the blood, kidney, liver, spleen, brain, feces and soft tissue around the plate. Radiographs showed normal undisturbed and completed healing of the osteotomy in all animals without any differences between the two groups over the entire observation period. Micro-CT analysis revealed overall tissue volume as well as tissue density to be comparable between the two groups. Mechanical testing showed comparable stiffness with an average stiffness relative to contralateral bones of 75.7 ± 16.1% in the silver-free control group compared to 69.7 ± 18.5% (p-value: 0.46). Semi-quantitative histopathological evaluation showed no remarkable difference in the analysis of the osteotomy gap healing or in the surrounding soft tissue area. There were detectable silver concentrations in the soft tissue around the plate after 10 weeks. Silver in the blood was only found in 3 animals within the first two weeks and all animals were free of silver afterwards. There were no detectable silver concentrations in the brain, liver, spleen, axillary lymph nodes and kidney. This study shows undisturbed osteotomy healing of the presented antimicrobial silver surface coating and a good biocompatibility in this rabbit model.

Antimicrobial Silver Multilayer Coating for Prevention of Bacterial Colonization of Orthopedic Implants

Due to increasing rates of periprosthetic joint infections (PJI), new approaches are needed to minimize the infection risk. The first goal of this study was to modify a well-established infection model to test surface-active antimicrobial systems. The second goal was to evaluate the antimicrobial activity of a silver multilayer (SML) coating. In vitro tests with SML items showed a >4 Log reduction in a proliferation assay and a 2.2 Log reduction in an agar immersion test (7 d). In the in vivo model blank and SML coated K-wires were seeded with ~2 × 104 CFU of a methicillin-sensitive Staphylococcus epidermidis (MSSE) and inserted into the intramedullary tibial canal of rabbits. After 7 days, the animals were sacrificed and a clinical, microbiological and histological analysis was performed. Microbiology showed a 1.6 Log pathogen reduction on the surface of SML items (p = 0.022) and in loosely attached tissue (p = 0.012). In the SML group 7 of 12 SML items were completely free of pathogens (cure rate = 58%, p = 0.002), while only 1 of 12 blank items were free of pathogens (cure rate = 8%, p = 0.110). No silver was detected in the blood or urine of the SML treated animals and only scarcely in the liver or adjacent lymph nodes. In summary, an in vivo infection model to test implants with bacterial pre-incubation was established and the antimicrobial activity of the SML coating was successfully proven.

A retrospective study of antibacterial iodine-coated implants for postoperative infection

Postoperative infection is one of the most serious complications in orthopedic surgery. We have developed and use iodine-coated implants to prevent and treat postoperative infection in compromised hosts. This study evaluated outcomes using iodine-coated implants for postoperative infections.We treated 72 postoperative infected patients using iodine-coated implants. Of these, 38 were males and 34 were females, with a mean age of 59.3 years. The mean follow-up period was 5.6 years. The patients included 23 with an infection following total knee arthroplasty, 20 following total hip arthroplasty, 11 following osteosynthesis, 11 following spine surgery, 6 following tumor excision, and 1 following osteotomy. Of these, 37 underwent single-stage surgery and 35 underwent staged revision surgery. We performed staged surgery in any case with active infection. The survival of iodine-coated implants was determined using Kaplan-Meier analysis. White blood cell (WBC) and C-reactive protein (CRP) levels were measured pre- and postoperatively. To evaluate the systemic effects of iodine, serum thyroid hormone levels were examined.Five patients underwent re-revision surgery. In 3 patients, periprosthetic infection recurred at an average of 18 months after surgery. The reinfection rate was 4.2%. These patients recovered following reimplantation of iodine-coated prostheses. No patients required amputation. The survival rate of iodine-coated implants was 91%. There were no signs of infection at the latest follow-up. The median WBC level was nearly in the normal range, and CRP levels returned to normal within 4 weeks after surgery. No abnormalities of thyroid gland function were detected.Iodine-coated titanium implants can be very effective in the treatment of postoperative infections. An iodine coating can be safely applied to infected regions.

Is surface modification effective to prevent periprosthetic joint infection? A systematic review of preclinical and clinical studies

BACKGROUND

With increasing recognition of the importance of biofilm formation in the pathogenesis of periprosthetic joint infection (PJI), a push towards finding solutions to prevent PJI via surface modification of prostheses is occurring. Unlike the promising in vitro antimicrobial effects of these surface modifications, the preclinical and clinical prophylactic effects vary and are debated. Therefore, we performed this systematic review to answer: (1) what kinds of methods of surface modification are used in preclinical and clinical studies to prevent PJI, (2) whether these modifications are effective to prevent PJI.

METHODS

Electronic searches were performed using PubMed, Embase and the Cochrane library databases up to and including December 2017 with predetermined criteria: (1) in vivo studies with (2) surface modification for prophylactic effects against infection. Both animal studies and clinical trials were included. Data were extracted and presented systematically.

RESULTS

Overall, 21 studies were included. Among these, fourteen were carried out in animal models and seven were clinical studies. In the animal studies, six used antibiotics and six silver modifications, while copper and Cationic Steroidal Antimicrobial-13 were each used for one study. In the seven clinical studies targeting patients with high infection risk, five of them focused on silver-coated prostheses and the remaining two studied iodine-coated implants. In all of the animal studies, when compared with the control group, the surface modified groups had a lower infection risk (RR ranging from 0 to 0.71). Clinical studies using silver-coated prostheses also demonstrated a lower infection risk (RR ranging from 0.24 to 0.70), while iodine-coated implants showed a 0% and 5% incidence of PJI in the two case series included.

DISCUSSION

The results from the publications included in this review indicate that surface modification, especially antibiotic and silver modifications, are helpful preventing PJI in both preclinical animal models and in clinical trials.

LEVEL OF EVIDENCE

III, systematic review of level III retrospective comparative studies and level IV case series and animal experiments.

High complication and revision rates after total femoral replacement: a retrospective single center analysis of indication, function, and complication

INTRODUCTION

Total femoral replacement (TFR) is a limb salvage procedure performed for large bony defects. However, it is often associated with major complications and reduced function. Data on limb preservation rates and functional outcomes after TFR are limited. The primary objective of this study is to assess indications, functional outcomes, and complications after TFR.

MATERIALS AND METHODS

We retrospectively analyzed all patients after TFR between 2006 and 2016. All patients received a modular mega endoprosthesis (MUTARS^®). Patients were grouped according to their initial indication for TFR: (1) fracture, (2) tumor, or (3) infection. We evaluated (i) patient survival, (ii) postoperative function with the Musculoskeletal Tumor Society Score (MSTS), knee strength, range of motion, and (iii) complications.

RESULTS

Between 2006 and 2016, TFR was performed in 22 patients with a mean age of 64 +/-17 years. Indications for TFR were tumor (n = 6), infection (n = 8) and fracture (n = 8). The mean follow-up (f/up) was 18 months. At final follow-up, mean MSTS was 24%. Mean knee flexion strength was reduced 63% compared to the contralateral leg (p = 0.004). At time of final f/up, 5 patients (22%) died, 5 (22%) underwent secondary hip exarticulation, and 12 (54%) suffered a major complication. At f/up, 11 patients had infections. Of these 11 patients, 5 died, 4 were treated with debridement, and 5 were treated with hip exarticulation. Fifteen patients survived with preserved limbs at f/up.

CONCLUSION

TFR is a salvage procedure with limited functional outcome and high complication rates. Nevertheless, the majority of our cohort could be treated successfully with limb salvage.

Bone ongrowth of a cementless silver oxide-containing hydroxyapatite-coated antibacterial acetabular socket

BACKGROUND

The silver oxide-containing hydroxyapatite-coated socket (KYOCERA, Osaka, Japan) is a cementless antibacterial implant that has both the osteoconductivity of the HA and the antibacterial activity of silver. The silver oxide-containing hydroxyapatite coating was shown to have good osteoconductivity and new bone formation in vitro and in vivo. However, the histological bone ongrowth of this implant has not been proven in a clinical study.

METHODS

We analyzed bone ongrowth using two silver oxide-containing hydroxyapatite-coated sockets that were removed in revision total hip arthroplasty for recurrent dislocation. A histomorphometric analysis was performed using a scanning electron microscope (SEM) connected to a CCD camera and an elemental analysis was performed by energy-dispersive elemental spectrometry (EDS).

RESULT

A white structure thought to be osseous tissue was attached to the retrieved socket surface macroscopically, and histological bone ongrowth of the silver oxide-containing hydroxyapatite coating of the socket was confirmed by SEM. In addition, the presence of silver in the silver oxide-containing hydroxyapatite coating was confirmed in an elemental analysis by EDS.

CONCLUSION

Histologically, the silver oxide-containing hydroxyapatite-coated socket presented bone ongrowth in this clinical study.

[Silver coating on tumour prostheses]

BACKGROUND

Modular endoprostheses, so-called "tumour or megaprostheses" are mainly used for limb salvage surgery after resection of malignant soft tissue or a bone tumour. Sometimes, this type of prosthesis is also used for revision surgeries after failed primary joint arthroplasty. Despite continuously improving techniques and quality management systems, periprosthetic infection is one of the most serious complications.

AIM OF THE STUDY

Review of the literature in the PubMed data base with the main focus on silver coatings in joint arthroplasty and their effect on infection rate, outcome and patients' safety.

RESULTS

The current literature shows that there is a beneficial role of silver coatings in megaprostheses in terms of revision rates for septic complications, especially following tumour resection with bad soft tissue coverage or in (multimorbid) high-risk patients, compared to uncoated implants.

DISCUSSION

Based on the results of previous publications examining blood or serum silver concentrations or silver levels in urine, silver coatings do not appear to have side effects, except for local argyria. Continuous monitoring of silver levels in blood or serum is still recommended, and additional long-term studies will be necessary to verify the effectiveness and safety of silver coatings.

The use of silver coating in hip megaprostheses: a systematic review

Retrospective studies of silver-coated hip implants have demonstrated promising results and safety profile, however, the potential benefits are so far unproven in prospective studies. Silver-coated implants may have a role in patients undergoing revision or primary surgery with a high risk of infection but as yet there are no human studies investigating silver in primary hip arthroplasty. Adequately powered robust prospective studies are needed in this area to determine if silver-coated implants would be efficacious and cost-effective. The purpose of this systematic review article is to review the current literature regarding the use of silver in hip arthroplasty. Our review showed that there is some encouraging evidence that silver coatings can reduce infection.

Two-stage cementless hip revision for peri-prosthetic infection with an antibacterial hydrogel coating: results of a comparative series

PURPOSE

The aim of this study was to investigate the hypothesis that a two-stage exchange procedure, performed with an antibiotic-loaded, fast-resorbable hydrogel coating, may provide better infection cure rate than a two-stage procedure without the coating, in patients affected by peri-prosthetic hip infection.

METHODS

In this case-control study, 27 patients, treated with a two-stage procedure, using cementless implants coated with an antibiotic-loaded hydrogel (DAC®, "Defensive Antibacterial Coating"), were compared with 27 matched controls, treated with a two-stage cementless revision procedure, without the coating.

RESULTS

At a mean follow-up of 2.7 (minimum 2.1-maximum 3.5) years, no evidence of infection, implant loosening, or adverse events were observed in the DAC-treated group, compared to four cases of infection recurrence in the control group.

CONCLUSIONS

Although in a relatively limited series of patients our data show that cementless two-stage hip revision, performed with an antibacterial hydrogel coating, may provide better infection control than two-stage without the coating, with reduced hospitalization time, these findings warrant further studies in the possible applications of antibacterial coating technologies to treat implant-related infections.