[Diagnostic and therapeutic work-up of infected tibial nonunion]. / Diagnostik und Therapie der infizierten Tibia-Pseudarthrose.

BACKGROUND: The failure of bone fracture healing is one of the major complications of fracture treatment, especially of the tibia due to its limited soft tissue coverage and high rate of open injuries. Although implant development is constantly progressing and modern surgical techniques are continuously improving, infected tibial nonunion plays a decisive role in terms of its variable clinical presentation. OBJECTIVE: This article provides guidelines for the successful surgical treatment of infected tibial nonunion. MATERIAL AND METHOD: Strategies are presented to identify infection as a cause of failure of fracture healing and to achieve infection and bone healing. RESULTS: A significant amount of tibial nonunions primarily thought to be aseptic ultimately turn out to be infected nonunions. CONCLUSION: The treatment of infected tibial nonunion requires extensive clinical, radiological and laboratory diagnostics as well as a profound biomechanical and biological understanding of the bone situation. This is the only way to achieve rapid osseous healing with as few revision interventions as possible.

The value of sonication in the differential diagnosis of septic and aseptic femoral and tibial shaft nonunion in comparison to conventional tissue culture and histopathology: a prospective multicenter clinical study.

BACKGROUND: Septic and aseptic nonunion require different therapeutic strategies. However, differential diagnosis is challenging, as low-grade infections and biofilm-bound bacteria often remain undetected. Therefore, the examination of biofilm on implants by sonication and the evaluation of its value for differentiating between femoral or tibial shaft septic and aseptic nonunion in comparison to tissue culture and histopathology was the focus of this study. MATERIALS AND METHODS: Osteosynthesis material for sonication and tissue samples for long-term culture and histopathologic examination from 53 patients with aseptic nonunion, 42 with septic nonunion and 32 with regular healed fractures were obtained during surgery. Sonication fluid was concentrated by membrane filtration and colony-forming units (CFU) were quantified after aerobic and anaerobic incubation. CFU cut-off values for differentiating between septic and aseptic nonunion or regular healers were determined by receiver operating characteristic analysis. The performances of the different diagnostic methods were calculated using cross-tabulation. RESULTS: The cut-off value for differentiating between septic and aseptic nonunion was ≥ 13.6 CFU/10 ml sonication fluid. With a sensitivity of 52% and a specificity of 93%, the diagnostic performance of membrane filtration was lower than that of tissue culture (69%, 96%) but higher than that of histopathology (14%, 87%). Considering two criteria for infection diagnosis, the sensitivity was similar for one tissue culture with the same pathogen in broth-cultured sonication fluid and two positive tissue cultures (55%). The combination of tissue culture and membrane-filtrated sonication fluid had a sensitivity of 50%, which increased up to 62% when using a lower CFU cut-off determined from regular healers. Furthermore, membrane filtration demonstrated a significantly higher polymicrobial detection rate compared to tissue culture and sonication fluid broth culture. CONCLUSIONS: Our findings support a multimodal approach for the differential diagnosis of nonunion, with sonication demonstrating substantial usefulness. LEVEL OF EVIDENCE: Level 2 Trial registration DRKS00014657 (date of registration: 2018/04/26).

Advances in the Treatment of Implant-Associated Infections of the Pelvis: Eradication Rates, Recurrence of Infection, and Outcome.

INTRODUCTION: Surgical site infections after operative stabilization of pelvic and acetabular fractures are rare but serious complications. The treatment of these infections involves additional surgical procedures, high health care costs, a prolonged stay, and often a worse outcome. In this study, we focused on the impact of the different causing bacteria, negative microbiological results with wound closure, and recurrence rates of patients with implant-associated infections after pelvic surgery. MATERIAL AND METHODS: We retrospectively analyzed a study group of 43 patients with microbiologically proven surgical site infections (SSI) after surgery of the pelvic ring or the acetabulum treated in our clinic between 2009 and 2019. Epidemiological data, injury pattern, surgical approach, and microbiological data were analyzed and correlated with long-term follow-up and recurrence of infection. RESULTS: Almost two thirds of the patients presented with polymicrobial infections, with staphylococci being the most common causing agents. An average of 5.7 (±5.4) surgical procedures were performed until definitive wound closure. Negative microbiological swabs at time of wound closure were only achieved in 9 patients (21%). Long-term follow-up revealed a recurrence of infection in only seven patients (16%) with an average interval between revision surgery and recurrence of 4.7 months. There was no significant difference of recurrence rate for the groups of patients with positive/negative microbiology in the last operative revision (71% vs. 78%). A positive trend for a correlation with recurrent infection was only found for patients with a Morel-Lavallée lesion due to run-over injuries (30% vs. 5%). Identified causing bacteria did not influence the outcome and rate of recurrence. CONCLUSION: Recurrence rates after surgical revision of implant-associated infections of the pelvis and the acetabulum are low and neither the type of causing agent nor the microbiological status at the timepoint of wound closure has a significant impact on the recurrence rate.

[Infected nonunion: diagnostic and therapeutic work-up]. / Infizierte Pseudarthrose: diagnostischer und therapeutischer Ablauf.

BACKGROUND: Septic nonunion is one of the major complications in fracture healing. The challenge is to identify the infection as the cause of nonunion first and then to achieve healing of the infection and the bone. OBJECTIVE: Because of the more heterogeneous appearance of an infected nonunion, the prevalence of germ detection in surgical nonunion revision is often underestimated. MATERIAL AND METHODS: In a retrospective study between 2010 and 2017, 86 patients with radiologically confirmed femoral shaft nonunion without clinical evidence and unremarkable medical history of a florid infection as the cause of nonunion, who had undergone primary single-stage surgical nonunion revision were analyzed. At least four intraoperatively obtained samples were evaluated for microbiological diagnosis. A distinction was made between tissue samples with subsequent 48­h short-term incubation and tissue samples with 14-day long-term cultivation. The finding "germ detection" was made if at least two of the samples demonstrated bacterial growth. RESULTS: In 18 of 86 patients with a nonunion preoperatively judged to be aseptic, positive bacterial evidence was obtained after short-term incubation. After long-term cultivation, positive bacterial detection was possible in 38 of 86 patients with a femoral shaft nonunion initially classified as aseptic. Regarding potential risk factors, the two groups demonstrated no relevant differences. In 29 patients, 1 pathogen was isolated from the obtained samples, whereas in the remaining 9 patients, a mixed culture with an average of 2.9 ± 0.5 different bacteria was detected. Identification revealed mainly low-virulence bacteria, most commonly Staphylococcus epidermidis. CONCLUSION: If the preoperative diagnostics including clinical, laboratory and radiological examination as well as a careful anamnesis reveal indications of a possible infectious event, the surgical nonunion revision should be performed in two stages with specimen collection before definitive nonunion revision. For microbiological diagnosis, several representative tissue samples should independently be obtained from the nonunion site and incubated for 14 days. Only in the absence of evidence of septic nonunion is a single-stage procedure suggested.

The AO trauma CPP bone infection registry: Epidemiology and outcomes of Staphylococcus aureus bone infection.

Bone infection represents a serious complication of orthopedic surgery and Staphylococcus aureus is the most common pathogen. To improve the understanding of host-pathogen interaction, we developed a biospecimen registry (AO Trauma CPP Bone Infection Registry) to collect clinical data, bacterial isolates, and serum from patients with S. aureus bone infection. A prospective multinational registry with a 12-month follow-up was created to include adult patients (18 years or older) with culture-confirmed S. aureus infection in long bones after fracture fixation or arthroplasty. Baseline patient attributes and details on infections and treatments were recorded. Blood and serum samples were obtained at baseline, 6, and 12 months. Patient-reported outcomes were collected at 1, 6, and 12 months. Clinical outcomes were recorded. Two hundred and ninety-two patients with fracture-related infection (n = 157, 53.8%), prosthetic joint infection (n = 86, 29.5%), and osteomyelitis (n = 49, 16.8%) were enrolled. Methicillin-resistant S. aureus was detected in 82 patients (28.4%), with the highest proportion found among patients from North American sites (n = 39, 48.8%) and the lowest from Central European sites (n = 18, 12.2%). Patient outcomes improved at 6 and 12 months in comparison to baseline. The SF-36 physical component summary mean (95% confidence interval) score, however, did not reach 50 at 12 months. The cure rate at the end of the study period was 62.1%. Although patients improved with treatment, less than two-thirds were cured in 1 year. At 12-month follow-up, patient-reported outcome scores were worse for patients with methicillin-resistant S. aureus infections.

Knee arthrodesis versus above-the-knee amputation after septic failure of revision total knee arthroplasty: comparison of functional outcome and complication rates.

BACKGROUND: After septic failure of total knee arthroplasty (TKA) and multiple revision operations resulting in impaired function, bone and/or soft-tissue damage a reconstruction with a revision arthroplasty might be impossible. Salvage procedures to regain mobility and quality of life are an above-the-knee amputation or knee arthrodesis. The decision process for the patient and surgeon is difficult and data comparing arthrodesis versus amputation in terms of function and quality of life are scarce. The purpose of this study was to analyse and compare the specific complications, functional outcome and quality of life of above-the-knee amputation (AKA) and modular knee-arthrodesis (MKA) after septic failure of total knee arthroplasty. METHODS: Eighty-one patients treated with MKA and 32 patients treated with AKA after septic failure of TKA between 2003 and 2012 were included in this cohort study. Demographic data, comorbidities, pathogens and complications such as re-infection, implant-failure or revision surgeries were recorded in 55MKA and 20AKA patients. Functional outcome with use of the Lower-Extremity-Functional-Score (LEFS) and the patients reported general health status (SF-12-questionnaire) was recorded after a mean interval of 55 months. RESULTS: A major complication occurred in more than one-third of the cases after MKA and AKA, whereas recurrence of infection was with 22% after MKA and 35% after AKA the most common complication. Patients with AKA and MKA showed a comparable functional outcome with a mean LEFS score of 37 and 28 respectively (p = 0.181). Correspondingly, a comparable physical quality of life with a mean physical SF-12 of 36 for AKA patients and a mean score of 30 for MKA patients was observed (p = 0.080). Notably, ten AKA patients that could be fitted with a microprocessor-controlled-knee-joint demonstrated with a mean LEFS of 56 a significantly better functional outcome than other amputee patients (p < 0.01) or MKA patients (p < 0.01). CONCLUSION: Naturally, the decision process for the treatment of desolate situations of septic failures following revision knee arthroplasty is depending on various factors. Nevertheless, the amputation should be considered as an option in patients with a good physical and mental condition.

The diagnostic value of [(18)F]FDG PET for the detection of chronic osteomyelitis and implant-associated infection.

PURPOSE: The diagnosis of osteomyelitis and implant-associated infections in patients with nonspecific laboratory or radiological findings is often unsatisfactory. We retrospectively evaluated the contributions of [(18)F]FDG PET and [(18)F]FDG PET/CT to the diagnosis of osteomyelitis and implant-associated infections, enabling timely and appropriate decision-making for further therapy options. METHODS: [(18)F]FDG PET or PET/CT was performed in 215 patients with suspected osteomyelitis or implant-associated infections between 2000 and 2013. We assessed the diagnostic accuracy of both modalities together and separately with reference to intraoperative microbial findings, with a mean clinical follow-up of 69 ± 49 months. RESULTS: Infections were diagnosed clinically in 101 of the 215 patients. PET and PET/CT scans revealed 87 true-positive, 76 true-negative, 38 false-positive, and 14 false-negative results, indicating a sensitivity of 86 %, a specificity of 67 %, a positive predictive value (PPV) of 70 %, a negative predictive value (NPV) of 84 % and an accuracy of 76 %. The sensitivity of PET/CT was 88 %, but specificity, PPV, NPV and accuracy (76 %, 76 %, 89 % and 82 %, respectively) were higher than those of stand-alone PET. CONCLUSION: [(18)F]FDG PET is able to identify with high sensitivity the presence of osteomyelitis in orthopaedic surgery patients with nonspecific clinical symptoms of infection.

FDG PET/CT dataset for navigation on femoral bone: a feasibility study.

FDG PET/CT has become a valuable tool in the diagnosis of the activity of chronic osteomyelitis. The surgical strategy in the treatment of chronic osteomyelitis is the identification of the bone focus and radical debridement of sequesters. The aim of the current study was the registration and use of the FDG PET/CT imaging datasets on a navigation system to provide diagnostic imaging based feedback during surgical procedures. For the present study, FDG PET/CT scans were acquired from artificial bones and cadaver bones with a local focus of activity. The DICOM data sets were merged using a navigation system. The referenced regions of interest were matched with fluoroscopic pictures to register the PET/CT DICOM datasets to the bone and direct visual control. Navigated targeting led to accurate results when verified with fluoroscopic images by targeting previously inserted reference points in artificial and cadaver bone. FDG PET/CT datasets are suitable for navigation and compatible with conventional planning and navigation software. The combination of diagnostic FDG PET/CT imaging with surgical navigation techniques could be a valuable tool for the accurate treatment of chronic osteomyelitis.

Clinical course, complication rate and outcome of segmental resection and distraction osteogenesis after chronic tibial osteitis.

INTRODUCTION: Radical segmental resection and subsequent distraction osteogenesis are considered the gold standard in the treatment of chronic tibial osteitis. We investigated the clinical course of treatment, particularly with respect to patients' quality of life, and the complication rate associated with this technique. METHODS: In this prospective case series, 25 patients (22 men, 3 women, average age: 46 years) with chronic post-traumatic tibial osteitis were managed operatively from 2006 to 2009. Standardised treatment included bacterial eradication by segmental resection, bone transport using Ilizarov apparatus, and docking manoeuvre. The follow-up rates during bacterial eradication, bone transport, post docking, and complete osseous consolidation were 100% while follow-up two years after completed consolidation was 76%. The main outcome measurements consisted of the quality of life (Medical Outcomes Study 36-Item Short Form Health Survey (SF-36 score)) and the virtual analogue scale (VAS) of pain during the five stages of therapy. Additionally, all complications and difficulties were documented. RESULTS: The average defect size was 5.3 cm (range: 3-13). The healing index was 57 days per cm transport (range: 18-172). The overall treatment time averaged 93 weeks (range: 38-183). Patients suffered 22 minor and 13 major complications including one amputation. The average complication rate per patient consisted of 0.88 minor and 0.52 major complications. After the period of bone transport, the physical and mental component summary scores increased continuously. After completed consolidation, the average mental summary score was comparable to a normal collective. CONCLUSIONS: Distraction osteogenesis is challenging for both the patient and the surgeon. The arduous and demanding nature of the clinical course subjects the patient to considerable mental and physical stress. Thankfully, the average physical and mental status of health continues to improve during the clinical course of treatment. The 2-year success rate of the distraction osteogenesis in an infected tibia is 96%.

Risk factors for failed two-stage procedure after chronic posttraumatic periprosthetic hip infections.

INTRODUCTION: The aim of the study was to identify risk factors of failed two-stage procedures in cases of chronic posttraumatic periprosthetic hip infections. PATIENTS AND METHODS: Between 2006 and 2008, 26 patients with chronic posttraumatic periprosthetic infections after hip arthroplasty were included. In all cases operative bacterial eradication was initiated. The therapy was carried out according to a standardized treatment protocol including the eradication of the bacterial infection and the prosthetic replacement after three negative intra-operative specimens as a two-stage procedure. Follow-up was performed at least 2 years after revision procedure. RESULTS: Twelve patients showed no signs of infectious recurrence 2 years after prosthetic hip revision therapy (46 %) and were assigned to group I. Group II is constituted by the other 14 patients (54 %). Four of them (16 %) suffered from an infectious recurrence after prosthetic hip replacement, ten patients (38 %) were characterised by a failed bacterial eradication. The spectrum of pathogens showed a significantly higher resistance pattern (p = 0.001) in group II, with a majority of methicillin-resistant Staphylococcus epidermidis (MRSE) and highly resistant Pseudomonas. In addition, patients of group II offered significantly higher American Society of Anesthesiology (ASA) scores (p = 0.015), the body mass index (BMI) was significantly elevated (p = 0.031) and received a significantly higher number of operative procedures (p = 0.016). CONCLUSIONS: A reduced general state of health, a high BMI and highly resistant pathogens are the main risk factors for a failed two-stage procedure after chronic posttraumatic periprosthetic hip infections. Therefore, different treatment strategies are required for a defined subgroup of patients.