Neutrophil extracellular traps and citrullinated fibrinogen contribute to injury in a porcine model of limb ischemia and reperfusion.

Background: Ischemia/reperfusion injury (IRI) is a complex pathological process, triggered by the restoration of blood flow following an interrupted blood supply. While restoring the blood flow is the only option to salvage the ischemic tissue, reperfusion after a prolonged period of ischemia initiates IRI, triggering a cascade of inflammatory responses ultimately leading to neutrophil recruitment to the inflamed tissue, where they release neutrophil extracellular traps (NETs). NETs are web-like structures of decondensed chromatin and neutrophilic proteins, including peptidyl-arginine deiminase 2 and 4 (PAD2, PAD4), that, once outside, can citrullinate plasma proteins, irreversibly changing their conformation and potentially their function. While the involvement of NETs in IRI is known mainly from rodent models, we aimed to determine the effect of NET formation and especially PADs-mediated extracellular protein citrullination in a porcine model of limb IRI. Methods: We conducted our study on amputated pig forelimbs exposed to 1 h or 9 h of ischemia and then reperfused in vivo for 12 h. Limb weight, edema formation, compartmental pressure were measured, and skeletal muscle was analyzed by immunofluorescence (TUNEL assay and dystrophin staining) to evaluate tissue damage. Fibrin tissue deposition, complement deposition and NETs were investigated by immunofluorescence. Citrullinated plasma proteins were immunoprecipitated and citrullinated fibrinogen was identified in the plasma by Western blot and in the tissue by immunofluorescence and Western blot. Results: Our data consolidate the involvement of NETs in a porcine model of limb IRI, correlating their contribution to damage extension with the duration of the ischemic time. We found a massive infiltration of NETs in the group subjected to 9 h ischemia compared to the 1 h and citrullinated fibrinogen levels, in plasma and tissue, were higher in 9 h ischemia group. We propose fibrinogen citrullination as one of the mechanisms contributing to the worsening of IRI. NETs and protein citrullination represent a potential therapeutic target, but approaches are still a matter of debate. Here we introduce the idea of therapeutic approaches against citrullination to specifically inhibit PADs extracellularly, avoiding the downstream effects of hypercitrullination and keeping PADs' and NETs' intracellular regulatory functions.

Transcriptome profiling of immune rejection mechanisms in a porcine vascularized composite allotransplantation model.

Background: Vascularized composite allotransplantation (VCA) offers the potential for a biological, functional reconstruction in individuals with limb loss or facial disfigurement. Yet, it faces substantial challenges due to heightened immune rejection rates compared to solid organ transplants. A deep understanding of the genetic and immunological drivers of VCA rejection is essential to improve VCA outcomes. Methods: Heterotopic porcine hindlimb VCA models were established and followed until reaching the endpoint. Skin and muscle samples were obtained from VCA transplant recipient pigs for histological assessments and RNA sequencing analysis. The rejection groups included recipients with moderate pathological rejection, treated locally with tacrolimus encapsulated in triglycerol-monostearate gel (TGMS-TAC), as well as recipients with severe end-stage rejection presenting evident necrosis. Healthy donor tissue served as controls. Bioinformatics analysis, immunofluorescence, and electron microscopy were utilized to examine gene expression patterns and the expression of immune response markers. Results: Our comprehensive analyses encompassed differentially expressed genes, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes pathways, spanning various composite tissues including skin and muscle, in comparison to the healthy control group. The analysis revealed a consistency and reproducibility in alignment with the pathological rejection grading. Genes and pathways associated with innate immunity, notably pattern recognition receptors (PRRs), damage-associated molecular patterns (DAMPs), and antigen processing and presentation pathways, exhibited upregulation in the VCA rejection groups compared to the healthy controls. Our investigation identified significant shifts in gene expression related to cytokines, chemokines, complement pathways, and diverse immune cell types, with CD8 T cells and macrophages notably enriched in the VCA rejection tissues. Mechanisms of cell death, such as apoptosis, necroptosis and ferroptosis were observed and coexisted in rejected tissues. Conclusion: Our study provides insights into the genetic profile of tissue rejection in the porcine VCA model. We comprehensively analyze the molecular landscape of immune rejection mechanisms, from innate immunity activation to critical stages such as antigen recognition, cytotoxic rejection, and cell death. This research advances our understanding of graft rejection mechanisms and offers potential for improving diagnostic and therapeutic strategies to enhance the long-term success of VCA.

A local drug delivery system prolongs graft survival by dampening T cell infiltration and neutrophil extracellular trap formation in vascularized composite allografts.

Introduction: The standard treatment for preventing rejection in vascularized composite allotransplantation (VCA) currently relies on systemic immunosuppression, which exposes the host to well-known side effects. Locally administered immunosuppression strategies have shown promising results to bypass this hurdle. Nevertheless, their progress has been slow, partially attributed to a limited understanding of the essential mechanisms underlying graft rejection. Recent discoveries highlight the crucial involvement of innate immune components, such as neutrophil extracellular traps (NETs), in organ transplantation. Here we aimed to prolong graft survival through a tacrolimus-based drug delivery system and to understand the role of NETs in VCA graft rejection. Methods: To prevent off-target toxicity and promote graft survival, we tested a locally administered tacrolimus-loaded on-demand drug delivery system (TGMS-TAC) in a multiple MHC-mismatched porcine VCA model. Off-target toxicity was assessed in tissue and blood. Graft rejection was evaluated macroscopically while the complement system, T cells, neutrophils and NETs were analyzed in graft tissues by immunofluorescence and/or western blot. Plasmatic levels of inflammatory cytokines were measured using a Luminex magnetic-bead porcine panel, and NETs were measured in plasma and tissue using DNA-MPO ELISA. Lastly, to evaluate the effect of tacrolimus on NET formation, NETs were induced in-vitro in porcine and human peripheral neutrophils following incubation with tacrolimus. Results: Repeated intra-graft administrations of TGMS-TAC minimized systemic toxicity and prolonged graft survival. Nevertheless, signs of rejection were observed at endpoint. Systemically, there were no increases in cytokine levels, complement anaphylatoxins, T-cell subpopulations, or neutrophils during rejection. Yet, tissue analysis showed local infiltration of T cells and neutrophils, together with neutrophil extracellular traps (NETs) in rejected grafts. Interestingly, intra-graft administration of tacrolimus contributed to a reduction in both T-cellular infiltration and NETs. In fact, in-vitro NETosis assessment showed a 62-84% reduction in NETs after stimulated neutrophils were treated with tacrolimus. Conclusion: Our data indicate that the proposed local delivery of immunosuppression avoids off-target toxicity while prolonging graft survival in a multiple MHC-mismatch VCA model. Furthermore, NETs are found to play a role in graft rejection and could therefore be a potential innovative therapeutic target.

The Inlet and Outlet Ratio: Retrospective and Prospective Study on an Improved Diagnostic Ultrasound Tool for Carpal Tunnel Syndrome.

Purpose: This study hypothesized that ratios of sonographic cross-sectional areas (CSAs) throughout the median nerve provide a more reliable tool for diagnosing carpal tunnel syndrome (CTS) than a single CSA value. We first tested this hypothesis in a retrospective cohort and subsequently confirmed it in a prospective blinded case-control series. Methods: Seventy patients were included in the retrospective study, and 50 patients and matched controls were included for the prospective study. We evaluated 4 CSAs, at the forearm, inlet, tunnel, outlet, and their ratios (Rforearm, Rinlet, Routlet, Routlet forearm) to evaluate compression of the median nerve. All patients underwent nerve conduction studies. For the prospective cohort, Disabilities of the Arm, Shoulder, and Hand scores and Boston Carpal Tunnel Questionnaire scores were evaluated, and ultrasound was performed by 2 examiners for each participant. Results: The Boston and Disabilities of the Arm, Shoulder, and Hand scores showed worse subjective function in patients with CTS than in controls. Three ultrasonography parameters (CSAs at the inlet, Rinlet, and Routlet) correlated significantly with subjective function. Age and Rinlet were significantly correlated with severity of CTS in the nerve conduction studies. In both the retrospective and prospective patient groups, the numbers of CSAs at the inlet and outlet were significantly higher than that of CSAs at the tunnel, whereas in the control group, no such compression was found. Of the single measurements, CSAs at the inlet had the best diagnostic performance with an optimized cutoff of 11.75 mm2. The Rinlet and Routlet ratios performed even better and showed the highest adjusted odds ratios for predicting CTS of all parameters (cutoff Rinlet, 1.25; Routlet, 1.45). Inter-observer correlation was generally high, with better values for single CSAs than for ratios. Conclusions: The 3 CSA measurements of the median nerve and the associated ratios improved diagnostic power for ultrasonography in CTS in our study. Type of study/level of evidence: Diagnostic I.

Outcomes of acute perilunate injuries-a systematic review.

PURPOSE: The objective of this systematic review was to perform epidemiological as well as clinical, radiological and patient-reported outcome analysis of surgically treated perilunate dislocations and fracture dislocations (PLDs and PLFDs) based on the so far largest pooled patient population to date. MATERIAL AND METHODS: This systematic review was written according to the updated guideline for reporting systematic reviews by the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. A comprehensive literature search of Pubmed, Embase, CENTRAL, and CINAHL databases was performed. All studies reporting on complications, radiological, functional and/or patient-reported outcomes of surgically treated acute PLDs and PLFDs with a minimum follow-up of 12 months were included. RESULTS: Twenty-six studies encompassing 550 patients with 553 operatively treated acute perilunate injuries (106 PLDs and 447 PLFDs) were included. The overall postoperative complication rate was 15.0% with secondary reduction loss representing the main contributing factor (10.1%). The overall reoperation rate was 10.4% and the incidence of salvage procedures was 2.8%. The risk for secondary reduction loss was higher for PLD than for PLFD injuries (24.2% vs. 7.0%, relative risk [RR] 3.5, 95% confidence interval [CI] 1.6-7.5). There was a higher overall complication rate for the combined dorsopalmar approach when compared to the isolated dorsal approach (17.4% vs. 8.4%, RR 0.5, 95% CI 0.2-1.0, number needed to treat [NNT] 11.2) and for open surgery versus arthroscopic surgery (17.4% vs. 4.8%, RR 0.3, 95% CI 0.1-0.9, NNT 8.0). A significant correlation was found between radiological osteoarthritis (rOA) and follow-up duration of the individual studies, while functional and patient-rated outcomes were comparable. CONCLUSIONS: Regardless of surgical technique, PLFDs appear to be less susceptible to secondary reduction loss than PLDs. Whenever possible, less invasive (e.g. arthroscopic) surgery should be performed to minimize postoperative complications. The rate of rOA is high and increases significantly with follow-up duration. Interestingly, rOA does not seem to correlate with reduced wrist function nor patient dissatisfaction and the need for salvage surgery is surprisingly rare. LEVEL OF EVIDENCE: Systematic review of level IV studies.

Schwannomas mistaken for metastases of melanoma in PET-CT: A diagnostic challenge with consequences.

The incidence of skin cancer and especially cutaneous malignant melanoma is rising, as are indications for staging examinations to detect metastasis. Schwannomas are common benign nerve tumors, which can be mistaken for metastasis even in highly specialized imaging. Risk of nerve lesion is high in inadvertent biopsy.

Atypical Pleomorphic Lipomatous Tumor of the Right Hand Mimicing Venous Malformation.

We present the case of a 31-year-old woman who was referred with a 12-month history of a tumor on the ulnar side of her dominant right hand. The eventual histopathologic diagnosis was an atypical pleomorphous lipomatous tumor, an entity that has only been recently classified in the World Health Organization Classification of Soft Tissue and Bone Tumors.

Trapeziometacarpal osteoarthritis - a stepwise therapeutic approach.

Osteoarthritis of the trapeziometarcarpal joint, also called rhizarthrosis, is a common finding in the second half of life. It has a higher prevalence in females and is of growing importance in ageing societies. A variety of conservative and surgical treatment options are known, including conservative treatment up to joint replacement. Without treatment, rhizarthrosis can lead to disabling pain and loss of hand function. The goal of this overview of treatment options is to present a stepwise approach that can be initiated by any physician. Treatment of trapeziometacarpal osteoarthritis should be started early with conservative measures such as splinting and physical therapy, which can be supplemented by oral and topical analgesics and local infiltrations subsequently. If all of these interventions do not provide sufficient relief, referral to a hand surgeon should be considered. Surgical strategies vary from arthroscopic debridement over trapeziectomy, with or without tendon interposition and ligament reconstruction, to interposition implants and total joint replacements. The planned intervention should be based on clinical and subjective functional limitations and associated degenerative changes, as well as the patient’s expectations and needs. The goal of this paper is to develop a treatment algorithm, leading to higher levels of patient functionality and satisfaction. Below we discuss the current literature and point out key treatment options used in our department.  .

Two weeks versus four weeks of antibiotic therapy after surgical drainage for native joint bacterial arthritis: a prospective, randomised, non-inferiority trial.

OBJECTIVE: The optimal duration of postsurgical antibiotic therapy for adult native joint bacterial arthritis remains unknown. METHODS: We conducted a prospective, unblinded, randomised, non-inferiority study comparing either 2 or 4 weeks of antibiotic therapy after surgical drainage of native joint bacterial arthritis in adults. Excluded were implant-related infections, episodes without surgical lavage and episodes with a follow-up of less than 2 months. RESULTS: We enrolled 154 cases: 77 in the 4-week arm and 77 in the 2-week arm. Median length of intravenous antibiotic treatment was 1 and 2 days, respectively. The median number of surgical lavages was 1 in both arms. Recurrence of infection was noted in three patients (2%): 1 in the 2-week arm (99% cure rate) and 2 in the 4-week arm (97% cure rate). There was no difference in the number of adverse events or sequelae between the study arms. Of the overall 154 arthritis cases, 99 concerned the hand and wrist, for which an additional subgroup analysis was performed. In this per-protocol subanalysis, we noted three recurrences: one in the 2-week arm (97 % cure); two in the 4-week arm (96 % cure) and witnessed sequelae in 50% in the 2-week arm versus 55% in the 4-week arm, of which five (13%) and six (13%) needed further interventions. CONCLUSIONS: After initial surgical lavage for septic arthritis, 2 weeks of targeted antibiotic therapy is not inferior to 4 weeks regarding cure rate, adverse events or sequelae and leads to a significantly shorter hospital stay, at least for hand and wrist arthritis. TRIAL REGISTRATION NUMBER: NCT03615781.

The Benefice of Mobile Parts' Exchange in the Management of Infected Total Joint Arthroplasties with Prosthesis Retention (DAIR Procedure).

Background: The management of prosthetic joint infections (PJI) with debridement and retention of the implant (DAIR) has its rules. Some authors claim that lacking the exchange of mobile prosthetic parts is doomed to failure, while others regard it as optional. Methods: Single-center retrospective cohort in PJIs treated with DAIR. Results: We included 112 PJIs (69 total hip arthroplasties, 9 medullary hip prostheses, 41 total knee arthroplasties, and 1 total shoulder arthroplasty) in 112 patients (median age 75 years, 52 females (46%), 31 (28%) immune-suppressed) and performed a DAIR procedure in all cases-48 (43%) with exchange of mobile parts and 64 without. After a median follow-up of 3.3 years, 94 patients (84%) remained in remission. In multivariate Cox regression analysis, remission was unrelated to PJI localization, pathogens, number of surgical lavages, duration of total antibiotic treatment or intravenous therapy, choice of antibiotic agents, immune-suppression, or age. In contrast, the exchange of mobile parts was protective (hazard ratio 1.9; 95% confidence interval 1.2⁻2.9). Conclusions: In our retrospective single-center cohort, changing mobile parts of PJI during the DAIR approach almost doubled the probability for long-term remission.

Chronic anterior sternoclavicular instability: technique and results of corrective clavicular osteotomy.

BACKGROUND: Chronic anterior sternoclavicular (SC) instability is a rare but potentially disabling condition. It can arise in conjunction with trauma or hyperlaxity, or both. Numerous surgical techniques have been described, but no gold standard exists. SC instability is often position-dependent and can be reduced with the arm in a specific position. METHODS: To directly address this issue, we used a technique of corrective osteotomy of the clavicle with the goal to reorient the articular portion of the medial end of the clavicle so that it remains stable in all functional positions of the arm. To illustrate the technique and the correction in space, we performed postoperative 3-dimensional computed tomography analyses of the shoulder girdle of 4 patients. Clinical scores were obtained at the final follow-up and compared with preoperative scores. RESULTS: Mean follow-up was 64 months (range, 19-191 months). The mean Constant score improved from 58 (range, 45-68) preoperatively to 73 (range, 69-84) postoperatively and the Subjective Shoulder Value from 42 (range, 15-80) to 79 (range, 50-100). All patients reported good or very good stability of the SC joint at the last follow-up. We recorded no intraoperative or direct postoperative complications. During follow-up, 3 patients underwent removal of the plate, 1 of them for plate breakage. The mean postoperative correction for combined rotations is given as a 3-dimensional angle and averaged 28.0° (range, 8.6°-39.7°). CONCLUSION: In this pilot study, medial corrective clavicular osteotomy using the described technique treated anterior SC instability with improvement of clinical shoulder function scores and good patient satisfaction. The technique appears simple and safe and deserves further evaluation.

Corrective Osteotomies of Phalangeal and Metacarpal Malunions Using Patient-Specific Guides: CT-Based Evaluation of the Reduction Accuracy.

BACKGROUND: Surgical planning of corrective osteotomies is traditionally based on conventional radiographs and clinical findings. In the past 10 years, 3-dimensional (3D) preoperative planning approaches with patient-specific guides have been developed. However, the application of this technology to posttraumatic deformities of the metacarpals and phalangeal bones has not yet been investigated. Our goal was to evaluate the feasibility of the surgical application to the latter and to evaluate the extent and precision of correction. METHODS: We present results of 6 patients (8 osteotomies) treated with phalangeal or metacarpal corrective osteotomy. Deformities were located in the third ray in 1, fourth ray in 3, and fifth ray in 4 cases. Six malunited metacarpal bones (1 intra-articular) and 2 deformed proximal phalanges were treated. Computer-based 3D preoperative planning using the contralateral hand as a template allowed the production of 3D-printed patient-specific guides that were used intraoperatively for navigation. The precision of the reduction was assessed using pre- and postoperative computed tomography by comparing the postoperative bone model with the preoperatively simulated osteotomy. Range of motion and grip strength were documented pre- and postoperatively. RESULTS: The mean follow-up time was 6 months (range: 5-11 months). Rotational deformity was reduced from a mean of 10.0° (range: 7.2°-19.3°) preoperatively to 2.3° (range: 0.7°-3.7°) postoperatively, and translational incongruency decreased from a mean of 1.4 mm (range: 0.7-2.8 mm) to 0.4 mm (range: 0.1-0.9 mm). CONCLUSION: Preliminary results indicate that a precise reduction for corrective osteotomies of metacarpal and phalangeal bones can be achieved by using 3D planning and patient-specific guides.

Three-Dimensional Correction of Complex Ankle Deformities With Computer-Assisted Planning and Patient-Specific Surgical Guides.

Three-dimensional computer-assisted preoperative planning, combined with patient-specific surgical guides, has become an effective technique for treating complex extra- and intraarticular bone malunions by corrective osteotomy. The feasibility and accuracy of such a technique has not yet been evaluated for ankle deformities. Four surgical cases of varying complexity and location were selected for evaluation. Three-dimensional bone models of the affected and contralateral healthy lower limb were generated from computed tomography scans. The preoperative planning software permitted quantification of the deformity in 3 dimensions and subsequent simulation of reduction, yielding a precise surgical plan. Patient-specific surgical guides were designed, manufactured, and finally applied during surgery to reproduce the preoperative plan. Evaluation of the postoperative computed tomography scans indicated adequate reduction accuracy with residual translational and rotational errors of <3 mm and <6°, respectively. Two patients required revision surgery owing to anterior osseous impingement or delayed union of the osteotomy. All patients were satisfied with the postoperative course and were pain free at a mean follow-up period of 2.5 (range 1 to 4) years. These promising results require confirmation in a clinical study with a larger sample size.

Danger signals activating the immune response after trauma.

Sterile injury can cause a systemic inflammatory response syndrome (SIRS) that resembles the host response during sepsis. The inflammatory response following trauma comprises various systems of the human body which are cross-linked with each other within a highly complex network of inflammation. Endogenous danger signals (danger-associated molecular patterns; DAMPs; alarmins) as well as exogenous pathogen-associated molecular patterns (PAMPs) play a crucial role in the initiation of the immune response. With popularization of the "danger theory," numerous DAMPs and PAMPs and their corresponding pathogen-recognition receptors have been identified. In this paper, we highlight the role of the DAMPs high-mobility group box protein 1 (HMGB1), interleukin-1α (IL-1α), and interleukin-33 (IL-33) as unique dual-function mediators as well as mitochondrial danger signals released upon cellular trauma and necrosis.