BACKGROUND: Our aim was to evaluate the prevalence and impact of unexpected positive intraoperative cultures (UPICs) on the outcome of presumed aseptic total knee and hip revision surgery.
METHODS: Data regarding patients who underwent elective total hip or knee revision surgery from January 2003 to July 2017 due to preoperatively presumed aseptic reasons was retrospectively reviewed. Partial revisions and patients who had follow-ups below 60 months were excluded from the study. In all surgeries, at least three intraoperative samples were taken for microbial culture. Failure was defined as the need for re-revision due to any cause at 5 years and/or the need for antibiotic suppressive therapy. Overall, 123 total hip and 431 total knee revisions were eligible for the study. All cases had at least a 5 year follow-up.
RESULTS: There were 420 cases (75.8%) that had all cultures negative, 108 (19.5%) had a single UPIC, and 26 (4.7%) had either ≥ 2 UPICs for the same microorganism or 1 UPIC for a virulent microorganism. This latter group was not associated with a significantly higher failure rate (2 of 26, 7.7%) compared to those in the aseptic group (54 of 528, 10.2%). Revisions performed within the first 24 months after primary implantation had a higher 5-year re-revision rate (19.3 versus 8.4%, P = 0.01), mainly attributable to aseptic causes.
CONCLUSIONS: Total hip and knee revisions with UPICs were not significantly associated with a higher re-revision risk at 5 years. Those revisions performed within the first 24 months after primary arthroplasty had a higher rate of any-cause failure.

Background: The aim of this study was to evaluate detection rates and risk factors for unsuspected proof of bacteria, as well as clinical and radiologic outcomes following femoral shaft nonunion without clinical signs of infection treated by a single-stage surgical revision procedure including reamed intramedullary exchange nailing. Methods: A retrospective cohort study was performed in a European level I trauma center between January 2015 and December 2022. Fifty-eight patients were included who underwent reamed intramedullary exchange nailing as a single-step procedure for surgical revision of posttraumatic diaphyseal femoral nonunion without any indications of infection in medical history and without clinical signs of local infection. Clinical details of the patients were analyzed and functional and radiologic long-term outcomes were determined. Results: In all patients, with and without proof of bacteria osseous, healing could be observed. The physical component summary of the SF-12 demonstrated significantly better results at least one year after the final surgical revision in case of a negative bacterial culture during exchange nailing. Conclusions: Clinical long-term outcomes demonstrated a trend towards better results following femoral shaft nonunion revision if there was no evidence for the presence of low-grade infected nonunion. In this case, a single-stage surgical procedure may be recommended.

Low back pain is one of the most common pathologies worldwide. When conservative treatment fails to yield good results, surgery is the recommended approach. Despite spinal fusion, some patients continue to experience persistent low back pain. This is where a series of studies come into play to detect the source of treatment failure. The use of bone scintigraphy with SPECT (single-photon emission computed tomography) in combination with computed tomography (CT) has greatly improved the anatomical localization of abnormalities found in SPECT. While pseudoarthrosis is a significant cause of spinal fusion failure, in recent years, it has been observed that certain low-virulence pathogens are also implicated in persistent low back pain. This is the focus of our study, in which we identified two patients with persistent low back pain after surgery, both of whom tested positive for chronic low-grade infection using SPECT/CT.

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.
METHODS: 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.
CONCLUSIONS: 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.
UNASSIGNED: HINTERGRUND: Die ausbleibende Knochenbruchheilung stellt gerade an der Tibia wegen ihrer begrenzten Weichteildeckung und hohen Rate an offenen Verletzungen eine der entscheidenden Komplikationen bei der Frakturbehandlung dar, obwohl die Implantatentwicklung ständig fortschreitet und die modernen Operationsverfahren kontinuierlich weiterentwickelt werden. Die infizierte Tibia-Pseudarthrose nimmt wegen ihres variablen klinischen Erscheinungsbildes eine besondere Rolle ein.
UNASSIGNED: Die vorliegende Arbeit möchte einen Handlungsleitfaden zur erfolgreichen chirurgischen Behandlung infizierter Tibia-Pseudarthrosen anbieten.
UNASSIGNED: Es werden Strategien präsentiert, wie die Infektion als Ursache der ausbleibenden Frakturheilung identifiziert sowie die Infekt- und Knochenheilung erreicht werden kann.
UNASSIGNED: Ein erheblicher Teil der primär als aseptisch eingeschätzten Tibia-Pseudarthrosen stellt sich letztlich als infizierte Pseudarthrose heraus.
UNASSIGNED: Die Behandlung der infizierten Tibia-Pseudarthrose erfordert eine umfangreiche klinische, radiologische und laborchemische Diagnostik sowie ein profundes biomechanisches und biologisches Verständnis der Knochensituation. Nur so lässt sich eine rasche knöcherne Heilung mit möglichst wenigen Revisionseingriffen erreichen.

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.
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.
METHODS: Level 2 Trial registration DRKS00014657 (date of registration: 2018/04/26).

Low-virulent microorganisms identified on pedicle screws by sonication fluid culture (SFC) are an important cause of implant loosening. While sonication of explanted material improves the detection rate, the risk of contamination exists and no standardized diagnostic criteria for chronic low-grade spinal implant-related infection (CLGSII) are stablished. Besides, the role of serum C-reactive protein (CRP) and procalcitonin (PCT) in CLGSII has not been adequately investigated.
Blood samples were collected prior to implant removal. To increase sensitivity, the explanted screws were sonicated and processed separately. Patients exhibiting at least one positive SFC were classified in the infection group (loose criteria). To increase specificity, the strict criteria only considered multiple positive SFC (≥ 3 implants and/or ≥ 50% of explanted devices) as meaningful for CLGSII. Factors which might promote implant infection were also recorded.
Thirty-six patients and 200 screws were included. Among them, 18 (50%) patients had any positive SFCs (loose criteria), whereas 11 (31%) patients fulfilled the strict criteria for CLGSII. Higher serum protein level was the most accurate marker for the preoperative detection of CLGSSI, exhibiting an area under the curve of 0.702 (loose criteria) and 0.819 (strict criteria) for the diagnosis of CLGSII. CRP only exhibited a modest accuracy, whereas PCT was not a reliable biomarker. Patient history (spinal trauma, ICU hospitalization and/or previous wound-related complications) increased the likelihood of CLGSII.
Markers of systemic inflammation (serum protein level) and patient history should be employed to stratify preoperative risk of CLGSII and decide the best treatment strategy.

Treatment of an infected shoulder prosthesis differs significantly from other joint infections because of the unique microbiome, dominated by Cutibacterium acnes. The cause of an infection, its time of onset, the bacterial spectrum and comorbidities have to be considered for evaluation and treatment. The diagnostic workup is sometimes complex, and the recognition of a chronic and low-grade infection is often difficult because typical clinical and laboratory markers may be normal. Treatment is surgical; the therapeutic spectrum ranges from arthroscopic irrigation and open debridement with the exchange of components to one- and two-stage revisions using antibiotic-loaded spacers. Early detection and a targeted, appropriate therapy are crucial to avoid extensive soft tissue and bone damage.
UNASSIGNED: Die Behandlung einer infizierten Schulterprothese ist eine Domäne der operativen Therapie. Sie unterscheidet sich von der anderer Gelenkinfektionen insbesondere wegen des besonderen Keimspektrums der Schulter, allen voran wegen der Besiedelung mit Cutibacterium acnes. Infektursache, Zeitpunkt des Auftretens, Keimspektrum und Komorbiditäten müssen zur Beurteilung und Therapieentscheidung herangezogen werden. Bei chronischen und „Low-grade-Infekten“ ist v. a. die Erkennung schwierig, weil typische Infektmerkmale und laborchemische Marker völlig normal sein können. Das Therapiespektrum reicht von der arthroskopischen Spülung über das offene Débridement mit Komponententausch bis hin zu ein- und zweizeitigen Prothesenwechseln unter Verwendung antibiotikabeladener Interimsprothesen. Entscheidend ist immer die frühzeitige Erkennung einer Infektion und deren sachgerechte Therapie, um ausgedehnte Folgeschäden an den Weichteilen und am Knochenlager zu vermeiden. Der Wechsel einer infizierten Schulterprothese wird aufgrund der hohen Anforderungen meist nur von spezialisierten Abteilungen sicher beherrscht.

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.
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 48‑h 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.
CONCLUSIONS: 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.
UNASSIGNED: HINTERGRUND: Die infizierte Pseudarthrose stellt eine der schwerwiegendsten Komplikationen bei der Frakturheilung dar. Die Herausforderung besteht darin, die Infektion zuerst als Ursache einer Pseudarthrose zu erkennen und dann die Heilung der Infektion und des Knochens zu erreichen.
UNASSIGNED: Aufgrund des heterogeneren Erscheinungsbildes infizierter Pseudarthrosen wird die Prävalenz eines Keimnachweises bei der operativen Pseudarthrosenrevision häufig unterschätzt.
UNASSIGNED: In einer retrospektiven Untersuchung zwischen 2010 und 2017 wurden 86 Patienten, die aufgrund einer radiologisch gesicherten Femurschaftpseudarthrose primär revidiert wurden und die ohne klinische Hinweise auf einen floriden Infekt als Ursache der Pseudarthrose waren, analysiert. Es wurden mindestens 4 intraoperativ gewonnene Proben mikrobiologisch ausgewertet. Dabei wurde zwischen Gewebeproben mit anschließender 48-stündiger Kurzzeitbebrütung und Gewebeproben mit 14-tägiger Langzeitkultivierung unterschieden. Der Befund „Keimnachweis“ wurde gestellt, wenn mindestens 2 der Proben ein Keimwachstum zeigten.
UNASSIGNED: Bei 18 der 86 präoperativ als aseptisch eingeschätzten Pseudarthrosen konnte nach Kurzzeitbebrütung ein positiver Keimnachweis erhoben werden. Nach Langzeitbebrütung war bei 38 von 86 Patienten ein positiver Keimnachweis möglich. Hinsichtlich potenzieller Risikofaktoren zeigten die beiden Gruppen keine relevanten Unterschiede. Bei 29 Patienten wurde ein einzelner Erregertyp aus den gewonnenen Proben isoliert, während bei den übrigen 9 Patienten eine Mischkultur mit durchschnittlich 2,9 ± 0,5 verschiedenen Bakterien nachgewiesen wurde. Bei der Keimidentifizierung fanden sich mit Staphylococcus epidermidis am häufigsten niedrigvirulente Bakterien.
UNASSIGNED: Ergibt die präoperative Diagnostik unter Einbeziehung der klinischen, laborchemischen und radiologischen Untersuchung sowie der Anamnese Hinweise auf ein mögliches Infektgeschehen, sollte die operative Revision zweizeitig mit Probengewinnung vor der definitiven Pseudarthrosenrevision erfolgen. Zur mikrobiologischen Diagnostik sollten mehrere repräsentative Gewebeproben unabhängig voneinander aus der Pseudarthrosenzone gewonnen und für 14 Tage bebrütet werden. Nur bei fehlenden Hinweisen auf eine infizierte Pseudarthrose wird das einzeitige Vorgehen vorgeschlagen.

METHODS: Monocentric, prospective, observational study.
OBJECTIVE: The clinical relevance of bacterial colonization of intervertebral discs is controversial. This study aimed to determine a possible relationship between bacterial and viral colonization and low-grade infection of the discs.
METHODS: We investigated 447 disc samples from 392 patients. Microbiological culture was used to examine the samples for bacterial growth, polymerase chain reaction (PCR) was used for detection of herpes simplex virus types 1 and 2 (HSV-1, HSV-2) and Cytomegalovirus (CMV), and histopathological analysis was used to detect signs of inflammation. The results were compared between subgroups organized according to gender, age, location of the samples, surgical approach, preoperative C-reactive protein (CRP), preoperative and 6 months postoperative Oswestry Disability Index (ODI) and Neck Disability Index (NDI), and Modic changes (MC) of the corresponding endplates. Also, we assessed the occurrence of postoperative infections within 6 months.
RESULTS: Microbiological culture was positive in 38.78% of the analyzed intervertebral discs. Altogether, 180 bacteria were isolated. Coagulase-negative staphylococci (CONS) (23.41%) and Cutibacterium acnes (18.05%) were the most frequently detected microorganisms. None of HSV-1, HSV-2, or CMV were detected. Male patients (p = 0.00036) and cervical segments (p = 0.00001) showed higher rates of positive culture results. Ventral surgical approaches ( p < 0.001) and Type 2 MC (p = 0.0127) were significantly associated with a positive microbiological result ( p< 0.001). Neither pre- nor postoperative ODI and NDI are associated with positive culture results. In 4 (1.02%) patients, postoperative spondylodiscitis occurred.
CONCLUSIONS: With 447 segments from 392 patients, we present one of the largest studies to date. While disc degeneration caused by HSV-1, HSV-2, and CMV seems unlikely, we found positive microbiological culture results in 38.78% of all discs. The role of local skin flora and sample contamination should be the focus of further investigations.
METHODS: III.
BACKGROUND: The study was registered at ClinicalTrials.gov (ID: NCT04712487, https://www.
RESULTS: gov/ct2/show/study/NCT04712487 ).

All implants are rapidly coated by the host with glycoproteins forming a thin capsule, and this is a normal response. Where an inflammatory stimulus such as infection is present, the capsule can thicken and become microvascularised and sometimes calcified. This inflammatory stimulus can take the form of leachable chemicals from the implant, or bacteria live or dead. The presence of live bacteria can lead to biofilm development, which is part of the chronic infective, inflammatory process. Staphylococcus epidermidis and Cutibacterium acnes have been implicated in chronic infection around breast implants, and some animal models suggest their involvement in capsule contracture. Molecular methods have revealed an array of microorganisms from samples of removed capsular material, though they are extremely sensitive to contamination. The relevance of the results to capsular contracture remains poorly understood. Bacteria of low virulence are shown associated with capsular contracture and calcification, and measures beyond those conventionally applied need to be investigated to limit perioperative contamination.