Infection after fracture osteosynthesis - Part I

Role of bone single photon emission computed tomography/computed tomography in managing chronic fracture-related infections: Determining the depth of infection and avoiding unnecessary bone procedures

PURPOSE

Fracture-related infections (FRIs) encompass a broad range of infections associated with bone fractures; they remain a significant clinical challenge. Here, we aimed to investigate the viability of focusing on soft-tissue management in patients suspected of chronic FRI, who exhibit no significant bony uptake on bone single photon emission computed tomography (SPECT)/computed tomography (CT) scans.

METHODS

Between January 2016 and January 2022, we managed 25 patients with chronic FRI or post-traumatic osteomyelitis using technetium 99m-methyl diphosphonate bone SPECT/CT to assess infection depth. Among them, 13 patients showing negligible bony uptake were included and categorized into two groups based on wound discharge reaching the bone/implant (Criteria 1, n = 6) or not (Criteria 2, n = 7).

RESULTS

Patients in the Criteria 1 group were treated with antibiotics and soft tissue debridement without bony procedure. The average duration of antibiotic therapy was 6.7 weeks. Treatments were individualized, including implant changes, local flaps, skin grafts, and negative pressure wound therapy. No recurrence was reported in the mean follow-up of 21.3 months. Patients in the Criteria 2 group were treated with oral antibiotics (mean duration: 5.9 weeks) and daily wound dressings. No recurrence was reported in the mean follow-up of 26.0 months, and no surgical interventions were required.

CONCLUSION

This study demonstrates the feasibility of focusing on soft-tissue management in patients with chronic FRI showing minimal bony uptake on bone SPECT/CT. Our treatment protocol avoided unnecessary surgical bone procedures, resulting in successful clinical outcomes with no recurrences.

In vitro elution characteristics of antibiotic-loaded polymethylmethacrylate cement and a calcium sulfate bone substitute using staphylococci isolated from orthopedic implant-associated infections

Polymethylmethacrylate (PMMA) remains the gold standard antibiotic carrier in the management of osteomyelitis. However, biodegradable ceramic carriers may exhibit more efficient antibiotic elution properties. Through zone of inhibition (ZOI) testing and biofilm killing assays, we assessed the in vitro elution efficacy of vancomycin released from calcium sulfate (PG-CSH) and PMMA beads as carriers on clinical strains of Staphylococcus aureus and Staphylococcus epidermidis, which were isolated from sonication fluid of orthopedic implant-associated infections. Overall, vancomycin-loaded PMMA and PG-CSH beads showed potency (ZOI above 4 cm² ) for up to 14 days against ATCC and clinical strains. Vancomycin-loaded PG-CSH beads displayed higher rates, exhibited a more stable antibiotic elution, had greater impacts on bacterial colony-forming unit counts and produced higher ZOIs; additionally, statistically significant differences (Student's t test) were observed in different time sets during the experiment. In the biofilm killing assay, PG-CSH loaded with vancomycin resulted in more bacterial deaths. In conclusion, in the present study, both PG-CSH and PMMA beads acted as good carriers, but greater antimicrobial elution and biofilm bacterial killing were observed with PG-CSH than PMMA. Future in vitro research should focus on testing other difficult-to-treat clinical strains, including multidrug resistant coagulase-negative staphylococci and Gram-negative bacilli.

Microbiology of fracture related infections

Fracture related infection remains a challenging complication that creates a heavy burden for orthopaedic trauma patients, their families, treating physicians and healthcare systems. Even current curative approaches (radical debridement, revision surgery and long-term antibiotics) often result in significant socioeconomic costs and the risk of life-long functional impairment to the patient. The prevalence of osteomyelitis due to trauma and surgical complications does not seem to be diminishing in our society and the emergence of antimicrobial resistance is a major health related concern with global relevance. Despite multi-drug resistant bacteria being on the rise universally, perioperative antibiotic prophylaxis in orthopaedic trauma care has only slightly changed in the last 25 years. Staphylococcus infections remain an increasing global concern, partially due to the resistance mechanisms developed by staphylococci to evade the host immune system and antibiotic treatment, and as such antibiotics are becoming increasingly ineffective. This paper will address fracture related infections in trauma patients, looking at the bacteriology of these infections, its clinical implications and evolving nature.

Fracture-Related infection - the role of the surgeon and surgery in prevention and treatment

Fracture-related infection (FRI) is a complication that impacts care costs, quality of life, and patient function. Great strides have been made in the last decade to obtain a common language for definition and diagnosis with the contribution of the Fracture-Related Infection Consensus. Although FRI treatment requires the participation of clinical specialists in infectious diseases for the management of antibiotics, it is necessary to understand that this complication is an eminently surgical pathology. The orthopedic surgeon must play a leadership role in the prevention and treatment of this complex disease. In this review, the most relevant aspects of prevention are updated, and a strategy for a sequential and comprehensive approach to the patient with this complication is presented.

Fracture-Related Infection in Bicolumnar Acetabular Fracture: A Case Report

Case: A 51-year-old man was affected by a fracture-related infection after a bicolumnar acetabular fracture. A significant alteration of the anatomy was present; thus, a 3D-printed model was useful for planning. A two-stage treatment was planned: in the first stage, implant removal with irrigation and debridement was performed, while in the second stage, a new osteosynthesis and implant of a THA were planned. During the second stage, the patient suffered a cardiogenic shock, so a third surgical procedure was necessary to implant THA. Targeted antibiotic therapy was administered eight weeks after the first stage, with the resolution of the infection. Conclusions: The infection was resolved following the recent guidelines and treating it like a periprosthetic infection with a two-stage revision. A collaboration between specialists in orthopaedics and infectious disease, respectively, and using multidisciplinary approach, were mandatory.

Prior use of antibiotics and immunosuppression are risk factors for fracture-related infection during the COVID-19 pandemic period: a Brazilian prospective cohort study

Background

Little is known about the role of COVID-19 pandemic period on the epidemiology of fracture-related infection (FRI). The present study summarizes the changes in the prevalence, microbiology, and risk factors of FRI during this period.

Methods

A prospective single-center cohort study assessed in the setting of COVID-19 pandemic (2020–2021), clinical, microbiological aspects, and independent risk factors (RF) of FRI. RFs were estimated by bivariate and multivariable analyses using prevalence ratio (PR) with significance at P < 0.05. Kaplan–Meier analysis was performed to evaluate treatment outcomes.

Results

Overall, 132 patients were analyzed, with patients with age over 65 years accounting 65.1%. FRI was diagnosed in 21(15.9%) patients. Independent RFs for FRI were recent and preoperative use of systemic antibiotics (PR: 7.0, 95% confidence interval (95% CI): 2.2 – 22.4, p = 0.001) and cancer (PR: 9.8, 95% CI: 2.0 – 48.8, p = 0.005). Cultures yielded Gram-negative bacteria in 77.8%, 33.3% were MDR.

Conclusions

We found higher rates of FRI, predominating in the elderly with closed femoral fractures during the COVID-19 pandemic. Prior use of antibiotics and immunosuppression conditions were independent factor for FRI. Our outcomes provide evidence to avoid the empirical use of antibiotics prior to surgery for fracture stabilization.

Use of Phage Cocktail BFC 1.10 in Combination With Ceftazidime-Avibactam in the Treatment of Multidrug-Resistant Pseudomonas aeruginosa Femur Osteomyelitis-A Case Report

High-energy trauma with severe bone fractures can be complicated by infection, leading to the development of osteomyelitis. Pseudomonas aeruginosa is an important causative agent of such infections because of its high virulence profile and ability to develop resistance against a wide range of antimicrobials quickly. P. aeruginosa biofilms cause treatment failure and relapsing infections. Bacteriophages are viruses that can be used to treat biofilm-associated infections. Moreover, the combination of phages with certain antimicrobials have demonstrated synergistic and additive effects. We present a case of a 21-year-old patient with relapsing multidrug-resistant (MDR) P. aeruginosa femur osteomyelitis that developed after a road accident, with a proximal right femoral Grade III B open fracture and severe soft tissue damage. Despite extensive antimicrobial treatment and multiple surgical interventions with wound debridement, the infection persisted, with subsequent development of femoral osteomyelitis with a fistula. Patient care management included femoral head excision with wound debridement, intravenous (IV) ceftazidime-avibactam, and the local application of the lytic Pseudomonas bacteriophage cocktail BFC 1.10. Nine months after the intervention, the patient did not show any clinical, radiological, or laboratory signs of inflammation; therefore, hip replacement was performed. Nevertheless, recurrent P. aeruginosa infection evolved at the distal side of the femur and was successfully treated with conventional antimicrobials. In this case, wound debridement combined with antibiotics and bacteriophages resulted in bacterial eradication of proximal femoral segment, avoiding leg amputation, but failed to treat osteomyelitis in distal bone segment. An in vitro assessment of the isolated MDR P. aeruginosa strain for biofilm formation and phage susceptibility was performed. Additionally, the antimicrobial effects of ceftazidime-avibactam and BFC 1.10 were determined on planktonic cell growth and bacterial biofilm prevention was evaluated. The isolated bacterial strains were susceptible to the bacteriophage cocktail. Strong biofilm formation was detected 6 h after inoculation. Ceftazidime-avibactam combined with BFC 1.10 was most effective in preventing planktonic cell growth and biofilm formation. In both cases, the required concentration of ceftazidime-avibactam decreased two-fold. This study demonstrates the possible use of bacteriophages and antibiotics in difficult-to-treat bone and soft tissue infections, where the additive effects of phages and antibiotics were observed.

Off-label use of orthopedical trauma implants in a low-income country

PURPOSE

Lack of resources, severe injuries, and logistical flaws force surgeons in low-income countries (LIC) to improvise during surgery and use implants "off-label." These off-label treatments are specific for the work of trauma surgeons in non-governmental (NGO) hospitals in LIC. The aim of this study is to show the need of off-label surgery in an environment of low resources by means of typical examples.

METHODS

Off-label treated fractures, the implant used instead, and the reason for off-label treatment were investigated in 367 injuries over a three month period in an NGO hospital in Sierra Leone.

RESULTS

Twenty-seven fractures were treated off-label with mostly K-wires (88.89%) and external fixators (51.85%). Three reasons for off-label use could be defined: no suitable implants (N = 14), the condition of soft tissues that did not allow internal osteosyntheses (N = 10), and implants not ready for surgery due to logistic flaws (N = 3). The implants needed were mostly locking plates.

CONCLUSION

Surgeons in similar settings must use K-wires and external fixators to treat complex fractures. Using implants off-label can help surgeons to treat fractures otherwise left untreated.

The use of negative pressure wound therapy for fracture-related infections following internal osteosynthesis of the extremity: A systematic review

This study aimed to systematically review the current literature on studies using negative pressure wound therapy (NPWT) or dressings following fracture-related infection (FRI) in internal osteosynthesis of the extremity. Articles were analyzed on fracture and wound healing and included when comparing or describing the use of either NPWT or dressings in FRI. We conducted a systematic literature search in four electronic databases: Embase, Medline, the Cochrane Library, and Scopus. The studies were screened by two authors using Covidence.org and evaluated for risk of bias. A total of 8576 records were identified. No articles compared NPWT to dressings. Seven case reports and three case series included a total of 115 patients treated for FRI. Fracture healing was achieved in 21 out of 67 patients treated with NPWT (4 amputations and 46 not described) and all 48 patients in the dressing group (4 patients needed additional sequestrectomy procedures). Five studies did not describe fracture healing. In 57 out of 67 patients treated with NPWT, the wounds were described as healed, closed, or requiring soft tissue reconstruction (4 amputations and six lacking description). The dressing group had complete wound coverage in 18 patients and partial coverage in 30 patients. Studies were generally at high risk of bias because of insufficient descriptions of both patient demographics and outcomes. No studies compared NPWT to dressings, and the existing literature is at high risk of bias. The included studies were of low-level evidence. NPWT can be neither recommended nor advised against to cover infected osteosynthesis.

Safety of Tedizolid as Suppressive Antimicrobial Therapy for Patients With Complex Implant-Associated Bone and Joint Infection due to Multidrug-Resistant Gram-Positive Pathogens: Results From the TediSAT Cohort Study

A prospective cohort study was conducted to evaluate long-term safety of tedizolid as suppressive antimicrobial treatment in patients with implant-associated bone and joint infection caused by multidrug-resistant gram-positive pathogens. Seventeen patients received tedizolid with a median duration of treatment of 6 months. No patients developed a serious adverse event.

The value of conventional radiographs for diagnosing internal fixation-associated infection

Background

The aim of the study is to  assess the diagnostic value of preoperative conventional radiographs for diagnosing infection associated with internal fixation devices.

Methods

We prospectively collected data of patients undergoing removal of internal fixation devices for any reason. Infection was diagnosed in case of purulence, sinus tract, positive histopathology and/or positive peri-implant tissue or sonication fluid culture. In radiographs radiolucent lines, implant breakage or displacement, or periosteal reaction were assessed. White blood cell count (WBC) and serum C-reactive protein (CRP) were determined at admission.

Results

We included 421 surgeries in 380 patients (median age 53.6 years, range 11–98 years), mainly indicated for infection (24.9%), nonunion (20.0%) and symptomatic implants (13.5%). Radiologic signs of infection included radiolucent lines (11.4%); implant breakage (12.4%) or displacement (10.7%); and periosteal reaction (7.1%). Infection was confirmed in 116 cases (27.6%). Only radiolucent lines (OR = 1.86 [95%CI: 1.00–3.38]) and periosteal reaction (OR = 2.48 [95%CI: 1.17–5.26]) were associated with infection, with a low sensitivity (16.4 and 12.1%, respectively), and high specificity (90.5 and 94.8%, respectively). Preoperative WBC and CRP had a sensitivity of 23.0 and 35.3%, and specificity of 91.7 and 89.5%, respectively.

Conclusions

Radiological signs suggestive of infection were uncommon. Radiolucency and periosteal reaction were associated with infection, though with low sensitivity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04170-3.

Current concepts in the prevention, diagnosis and treatment of fracture-related infection (FRI)

Fracture-related infection (FRI) is one of the most challenging complications following operative management of fractures. It can have profound implications for the patient, can be associated with considerable morbidity and often lead to impaired outcomes. There are significant healthcare-related costs. In recent years, there has been significant progress towards developing preventative strategies. Furthermore, diagnostic algorithms and management protocols have recently been reported. Lack of a strong evidence base has previously hindered efforts to implement these and develop established standards of care. There are multiple aspects of care that need to be considered and a multi-disciplinary approach is recommended. In this narrative review, we present the most up-to-date recommendations in the prevention, diagnosis and management of FRI.

[Management of suspected early infection after osteosynthesis]

The infection rate after fracture osteosynthesis depends on many factors. The postoperative infection rate after osteosynthesis (inpatient treatment) was between 1.15% and 2.04% for the years 2017-2019. The total number of postoperative wound infections was estimated at around 225,000 annually in 2018. Essential factors for reducing the infection rate after osteosynthesis are the favorable choice of the timing of the operation and the surgical procedure as well as the treatment of relevant secondary diseases. If a postoperative wound infection is suspected critical assessment of the wounds in the postoperative course is essential in order to be able to identify and treat this complication at an early stage. After osteosynthesis, early diagnosis of a peri-implant infection and differentiated surgical and antibiotic treatment are the prerequisites for the best possible treatment success.

Classifying Intracortical Brain-Machine Interface Signal Disruptions Based on System Performance and Applicable Compensatory Strategies: A Review

Brain-machine interfaces (BMIs) record and translate neural activity into a control signal for assistive or other devices. Intracortical microelectrode arrays (MEAs) enable high degree-of-freedom BMI control for complex tasks by providing fine-resolution neural recording. However, chronically implanted MEAs are subject to a dynamic in vivo environment where transient or systematic disruptions can interfere with neural recording and degrade BMI performance. Typically, neural implant failure modes have been categorized as biological, material, or mechanical. While this categorization provides insight into a disruption's causal etiology, it is less helpful for understanding degree of impact on BMI function or possible strategies for compensation. Therefore, we propose a complementary classification framework for intracortical recording disruptions that is based on duration of impact on BMI performance and requirement for and responsiveness to interventions: (1) Transient disruptions interfere with recordings on the time scale of minutes to hours and can resolve spontaneously; (2) Reversible disruptions cause persistent interference in recordings but the root cause can be remedied by an appropriate intervention; (3) Irreversible compensable disruptions cause persistent or progressive decline in signal quality, but their effects on BMI performance can be mitigated algorithmically; and (4) Irreversible non-compensable disruptions cause permanent signal loss that is not amenable to remediation or compensation. This conceptualization of intracortical BMI disruption types is useful for highlighting specific areas for potential hardware improvements and also identifying opportunities for algorithmic interventions. We review recording disruptions that have been reported for MEAs and demonstrate how biological, material, and mechanical mechanisms of disruption can be further categorized according to their impact on signal characteristics. Then we discuss potential compensatory protocols for each of the proposed disruption classes. Specifically, transient disruptions may be minimized by using robust neural decoder features, data augmentation methods, adaptive machine learning models, and specialized signal referencing techniques. Statistical Process Control methods can identify reparable disruptions for rapid intervention. In-vivo diagnostics such as impedance spectroscopy can inform neural feature selection and decoding models to compensate for irreversible disruptions. Additional compensatory strategies for irreversible disruptions include information salvage techniques, data augmentation during decoder training, and adaptive decoding methods to down-weight damaged channels.

General treatment principles for fracture-related infection: recommendations from an international expert group

Fracture-related infection (FRI) remains a challenging complication that creates a heavy burden for orthopaedic trauma patients, their families and treating physicians, as well as for healthcare systems. Standardization of the diagnosis of FRI has been poor, which made the undertaking and comparison of studies difficult. Recently, a consensus definition based on diagnostic criteria for FRI was published. As a well-established diagnosis is the first step in the treatment process of FRI, such a definition should not only improve the quality of published reports but also daily clinical practice. The FRI consensus group recently developed guidelines to standardize treatment pathways and outcome measures. At the center of these recommendations was the implementation of a multidisciplinary team (MDT) approach. If such a team is not available, it is recommended to refer complex cases to specialized centers where a MDT is available and physicians are experienced with the treatment of FRI. This should lead to appropriate use of antimicrobials and standardization of surgical strategies. Furthermore, an MDT could play an important role in host optimization. Overall two main surgical concepts are considered, based on the fact that fracture fixation devices primarily target fracture consolidation and can be removed after healing, in contrast to periprosthetic joint infection were the implant is permanent. The first concept consists of implant retention and the second consists of implant removal (healed fracture) or implant exchange (unhealed fracture). In both cases, deep tissue sampling for microbiological examination is mandatory. Key aspects of the surgical management of FRI are a thorough debridement, irrigation with normal saline, fracture stability, dead space management and adequate soft tissue coverage. The use of local antimicrobials needs to be strongly considered. In case of FRI, empiric broad-spectrum antibiotic therapy should be started after tissue sampling. Thereafter, this needs to be adapted according to culture results as soon as possible. Finally, a minimum follow-up of 12 months after cessation of therapy is recommended. Standardized patient outcome measures purely focusing on FRI are currently not available but the patient-reported outcomes measurement information system (PROMIS) seems to be the preferred tool to assess the patients' short and long-term outcome. This review summarizes the current general principles which should be considered during the whole treatment process of patients with FRI based on recommendations from the FRI Consensus Group.Level of evidence: Level V.

Current therapies in treatment and prevention of fracture wound biofilms: why a multifaceted approach is essential for resolving persistent infections

Traumatic orthopedic injuries, particularly extremity wounds, are a significant cause of morbidity. Despite prophylactic antibiotic treatment and surgical intervention, persistent infectious complications can and do occur. Persistent bacterial infections are often caused by biofilms, communities of antibiotic tolerant bacteria encased within a matrix. The structural and metabolic differences in this mode of growth make treatment difficult. Herein, we describe both established and novel, experimental treatments targeted at various stages of wound healing that are specifically aimed at reducing and eliminating biofilm bacteria. Importantly, the highly tolerant nature of these bacterial communities suggests that most singular approaches could be circumvented and a multifaceted, combinatorial approach will be the most effective strategy for treating these complicated infections.