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Filippo Migliorini,1,2 Martina Feierabend,1 Ulf Krister Hofmann1 1Department of Orthopaedic, Trauma, and Reconstructive Surgery, RWTH University Medical Centre, Aachen, 52074, Germany; 2Department of Orthopedics and Trauma Surgery, Academic Hospital of Bolzano (SABES-ASDAA), Teaching Hospital of Paracelsus Medical University, 39100 Bolzano, ItalyCorrespondence: Filippo Migliorini, Department of Orthopaedic, Trauma, and Reconstructive Surgery, RWTH University Hospital, Pauwelsstraße 30, Aachen, 52074, Germany, Tel +49 0241 80-35529, Email migliorini.md@gmail.comAbstract: Osteoarthritis of the knee is common. Early sports trauma or cartilage defects are risk factors for osteoarthritis. If conservative treatment fails, partial or total joint replacement is often performed. A joint replacement aims to restore physiological biomechanics and the quality of life of affected patients. Total knee arthroplasty is one of the most performed surgeries in musculoskeletal medicine. Several developments have taken place over the last decades that have truly altered the way we look at knee arthroplasty today. Some of the fascinating aspects will be presented and discussed in the present narrative review.Keywords: knee, arthroplasty, replacement, implant, materials, robotic, artificial intelligence

Background: In healthy articular cartilage, chondrocytes are found along arcades of collagen fibers as Single Strings. With onset of cartilage degeneration this pattern changes to Double Strings. In the course of osteoarthritis Small Clusters, and finally Big Clusters form. In highly degenerated articular cartilage, another poorly understood pattern is found where chondrocyte morphology differs considerably, and the distribution of cells is diffuse. Progression of osteoarthritis is accompanied by key processes such as chondrocyte proliferation, apoptosis, hypertrophic differentiation, inflammation, and angiogenesis. The aim of this exploratory study was to identify biomarkers for these processes in the context of spatial cellular organizational changes in articular cartilage., Methods: Cartilage explants (n = 166 patients) were sorted according to their predominant cellular pattern. Quantitative or semi-quantitative analysis of 39 biomarkers were performed by multiplex assay (31) or ELISA (8), and qualitative analysis on 12 immunohistochemical markers., Results: Hypertrophic differentiation (e.g. type-X collagen, osteopontin, osteocalcin and interleukin-6) and angiogenesis were associated with changes in chondrocyte organisation. First changes take place already at the transition from Single Strings to Double Strings. Drastic changes in the appearance of numerous biomarkers are found at the transition from Big Clusters to Diffuse., Conclusion: Key processes in osteoarthritis and their biomarkers seem to depend on the spatial distribution of chondrocytes in articular cartilage. Abrupt changes in biomarker occurrence were observed between Big Clusters and Diffuse insinuating that the Diffuse pattern is composed of a different cell population or at least a different form of chondrocyte morphology., The Translational Potential of This Article: In situ identification of the different spatial chondrocyte patterns by fluorescence microscopy has already been established in the recent past. Analysing human in-situ cartilage explants rather than isolated OA chondrocytes closes the gap between in vitro and in vivo studies and as such, stretches a big step towards translation of the observed findings. The direct association between tissue biomarker profile and cellular arrangements representing different states of OA sheds new light on the molecular and cellular physiopathology, especially in the context of larger processes such as angiogenesis, cellular proliferation, differentiation, and apoptosis. This also opens an interesting perspective for future investigation of such biomarkers and processes in clinical studies., (© 2024 The Authors.)

Introduction: Venous thromboembolism (VTE) is a major concern following total knee arthroplasty (TKA). The optimal pharmacological prophylaxis remains, however, controversial. The present investigation compared several non-vitamin K antagonist oral anticoagulants commonly employed as VTE prophylaxis following TKA. A Bayesian network meta-analysis was conducted to compare apixaban, aspirin, dabigatran, edoxaban, enoxaparin, fondaparinux, and rivaroxaban. The outcomes of interest were to compare the rate of deep venous thrombosis (DVT), pulmonary embolism (PE), and major and minor haemorrhages., Methods: This study was conducted according to the PRISMA Extension Statement for Reporting of Systematic Reviews Incorporating Network Meta-Analyses of Health Care Interventions. In March 2024, PubMed, Web of Science, and Google Scholar were accessed with no time constraints. All randomised controlled trials (RCTs) comparing two or more drugs for the prevention of VTE following TKA were considered for inclusion., Results: Data from 29,678 patients were collected. Of them, 67% (19,884 of 29,678 patients) were women. The mean age of the patients was 66.8 ± 2.8 years, and the mean BMI was 29.2 ± 1.5 kg/m 2 . There was comparability in age, sex, and BMI at baseline. Apixaban 5 mg, dabigatran 220 mg, and rivaroxaban 10 mg were the most effective in reducing the rate of DVT. Apixaban 5 mg, enoxaparin 60 mg, and rivaroxaban 40 mg were the most effective in reducing the rate of PE. Apixaban 5 mg, rivaroxaban 10 mg, and apixaban 10 mg were associated with the lowest rate of major haemorrhages. Apixaban 5 mg and 20 mg, and dabigatran 220 mg were associated with the lowest rate of minor haemorrhages., Conclusion: Administration of apixaban 5 mg demonstrated the best balance between VTE prevention and haemorrhage control following TKA., Level of Evidence: Level I, network meta-analysis of RCTs., (© 2024. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

Conventional radiography is regularly used to evaluate complications after total hip arthroplasty. In various recent consensus meetings, however, plain radiographs of a potentially infected hip joint have been judged as being only relevant to exclude diagnoses other than infection. Solid data on radiographic presentations of periprosthetic joint infection (PJI) are scarce. As a result, the prognostic value of radiological features in low-grade PJI remains uncertain. The present review article aims to present an overview of the available literature and to develop ideas on future perspectives to define the diagnostic possibilities of radiography in PJIs of the hip. The primary outcome of interest of this systematic review was the radiologic presentation of periprosthetic joint infections of the hip. As secondary outcome of interest served the sensitivity and specificity of the radiologic presentation of periprosthetic joint infections. Of the included articles, 26 were reviews, essays, or case reports and only 18 were clinical studies. Typical radiologic abnormalities of PJI were a periosteal reaction, a wide band of radiolucency at the cement-bone or metal-bone interface, patchy osteolysis, implant loosening, bone resorption around the implant, and transcortical sinus tracts. The frequency of their occurrence is still inadequately defined. A deeper understanding of the underlying causes and the relation between microorganisms to radiologic abnormalities can probably help clinicians in the future to diagnose a PJI. This is why further research shall focus on the radiographic features of PJI., (© 2024. The Author(s).)

The pericellular matrix (PCM) serves a critical role in signal transduction and mechanoprotection in chondrocytes. Osteoarthritis (OA) leads to a gradual deterioration of the cartilage, marked by a shift in the spatial arrangement of chondrocytes from initially isolated strands to large cell clusters in end-stage degeneration. These changes coincide with progressive enzymatic breakdown of the PCM. This study aims to assess the role and involvement of specific matrix metalloproteinases (MMPs) in PCM degradation during OA. We selected cartilage samples from 148 OA patients based on the predominant spatial chondrocyte patterns. The presence of various MMPs (-1,-2,-3,-7,-8,-9,-10,-12,-13) was identified by multiplexed immunoassays. For each pattern and identified MMP, the levels and activation states (pro-form vs. active form) were measured by zymograms and western blots. The localization of these MMPs was determined using immunohistochemical labeling. To verify these results, healthy cartilage was exposed to purified MMPs, and the consecutive structural integrity of the PCM was analyzed through immunolabeling and proximity ligation assay. Screening showed elevated levels of MMP-1,-2,-3,-7, and -13, with their expression profile showing a clear dependency of the degeneration stage. MMP-2 and -7 were localized in the PCM, whereas MMP-1,-7, and -13 were predominantly intracellular. We found that MMP-2 and -3 directly disrupt collagen type VI, and MMP-3 and -7 destroy perlecan. MMP-2, -3, and -7 emerge as central players in early PCM degradation in OA. With the disease's initial stages already displaying elevated peaks in MMP expression, this insight may guide early targeted therapies to halt abnormal PCM remodeling. STATEMENT OF SIGNIFICANCE: Osteoarthritis (OA) causes a gradual deterioration of the articular cartilage, accompanied by a progressive breakdown of the pericellular matrix (PCM). The PCM's crucial function in protecting and transmitting signals within chondrocytes is impaired in OA. By studying 148 OA-patient cartilage samples, the involvement of matrix metalloproteinases (MMPs) in PCM breakdown was explored. Findings highlighted elevated levels of certain MMPs linked to different stages of degeneration. Notably, MMP-2, -3, and -7 were identified as potent contributors to early PCM degradation, disrupting key components like collagen type VI and perlecan. Understanding these MMPs' roles in initiating OA progression, especially in its early stages, provides insights into potential targets for interventions to preserve PCM integrity and potentially impeding OA advancement., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Objective: The decision on whether or not and how to treat a local cartilage defect is still made intraoperatively based on the visual presentation of the cartilage and findings from indentations with an arthroscopic probe. The treatment decision is then usually based on grading according to established classifications systems, which, therefore, need to have high reliability and accuracy. The aim of the present study was to evaluate the reliability and accuracy of the Outerbridge classification in staging cartilage defects., Methods: We performed an observer arthroscopic study using the Outerbridge classification on seven fresh-frozen human cadaveric knees, which collectively exhibited nine cartilage defects. To evaluate accuracy, defect severity was verified through histological examination. Interrater and intrarater reliabilites were calculated using Cohen's kappa and the intra-class correlation coefficient (ICC 3.1)., Results: The interrater and intrarater reliability for the Outerbridge classification ranged from poor to substantial, with 0.24 ≤ κ ≤ 0.70 and κ = 0.55 to κ = 0.66, respectively. The accuracy evaluated by comparison with the histological examination was 63% overall. The erroneous evaluations were, however, still often at the discrimination of grade 2 and 3. We did not find any relationship between higher experience and accuracy or intraobserver reliability. Taken together, these results encourage surgeons to further use diagnostic arthroscopy for evaluating cartilage lesions. Nevertheless, especially in grade 2 and 3, deviations from the histology were observed. This is, however, the point where a decision is made on whether to surgically address the defect or not., Conclusion: Diagnostic arthroscopy is the standard for cartilage lesion assessment, yet interobserver reliability is fair to substantial. Caution is warranted in interpreting varied observer results. The accuracy of the "simpler" Outerbridge classification is insufficient compared to histological examinations, highlighting the need for improved techniques in guideline-based intraoperative decision-making., (© 2024 The Authors. Orthopaedic Surgery published by Tianjin Hospital and John Wiley & Sons Australia, Ltd.)

Introduction: The present study evaluated whether patient demographic characteristics influence the subsidence of the stem in total hip arthroplasty (THA). The following characteristics were evaluated: age, height, weight, and sex. The association between the time elapsed from the THA implantation and the amount of stem subsidence was also investigated., Methods: The records of patients who underwent THA in the period between 2016 and 2023 were accessed. All patients underwent two-staged bilateral THA using cementless DePuy collarless Corail (DePuy Synthes, Raynham, MA, USA) stems. The following parameters were measured and compared to assess stem subsidence: distance from the proximal femur at the stem bone interface and the medial apex of the regular triangle built within the trochanter minor (point A); distance from the medial apex of the regular triangle built within the trochanter minor and the distal portion of the femoral stem (point B)., Results: Overall, 294 patients were included. 62% (182 of 294 patients) were women. 45% (134 of 296 THAs) were on the right side. The mean age was 64.9 ± 10.4 years. The mean BMI was 28.3 ± 5.1 kg/m 2 . The mean length of the follow-up was 14.4 ± 11.0 months. The mean subsidence in point A was 2.1 mm (P < 0.0001), and that in point B was 3.1 mm (P < 0.0001). There was evidence of a weak positive association between patient weight (P < 0.0001), age (P = 0.03), follow-up (P = 0.002) and the amount of stem subsidence. Patient height did not demonstrate any association with the amount of stem subsidence (P = 0.07). There was no difference in stem subsidence between women and men (P = 0.9)., Conclusion: Stem subsidence in THA using cementless DePuy collarless Corail implants is approximately 2.6 mm after 14.4 months. Greater patient weight, age, and longer time elapsed from THA implantation were associated with greater stem subsidence. Patient height and sex did not demonstrate any influence on the amount of stem subsidence. These results must be considered in light of the limitations of the present study., (© 2023. The Author(s).)

Background: The present systematic review investigated the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient-acceptable symptom state (PASS) of several frequent and established PROMs used to assess patients who have undergone TKA. This study was conducted according to the 2020 PRISMA statement., Methods: In September 2023, PubMed, Web of Science, and Embase were accessed with no time constraint All clinical studies investigating tools to assess the clinical relevance of PROMs used to evaluate patients having received TKA were accessed. Only studies which evaluated the MCID, PASS, or SCB were eligible. The PROMs of interest were the Forgotten Joint Score-12 (FJS-12), the Oxford Knee Score (OKS), the Knee Injury and Osteoarthritis Outcome Score (KOOS) and its related subscales activity of daily living (ADL), pain, quality of life (QoL), sports and recreational activities, and symptoms, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score, the Knee Society Score (KSS) and related function score, and the Short Form-12 (SF-12) and Short Form-36 (SF-36)., Results: Data from 29,737 patients were collected. The overall risk of bias was low to moderate. The great variability of thresholds for MCID, SCB and PASS between questionnaires but also between investigated aspects was noted, whereby MCIDs for the SF-36 appear lower than for knee-specific questionnaires., Conclusion: Despite its critical role from a patient's perspective, the dimension of SCB is still neglected in the literature. Moreover, thresholds for the different concepts need to be condition-specific. We encourage authors to specifically report such data in future studies and to adhere to previously reported definitions to allow future comparison. Level of evidence Level IV, systematic review and meta-analysis., (© 2024. The Author(s).)

Total hip arthroplasty (THA) is a common procedure for patients suffering from hip pain e.g. from osteoarthritis, osteonecrosis, or hip fractures. The satisfaction of patients undergoing THA is influenced by the choice of implant type and material, with one key factor being the selection of the appropriate material combination for the bearing surface. In this Bayesian network meta-analysis, we investigated the impact of material combinations for the bearing surface on the longevity of hip implants. The wear penetration rate per year and the total wear penetration in the liner resulting from different material combinations, as well as the survival rate at last follow-up, were examined. We analyzed a total of 663,038 THAs, with 55% of patients being women. Mean patient age was 59.0 ± 8.1 years and mean BMI 27.6 ± 2.6 kg/m 2 . The combination of an aluminium oxide (Al 2 O 3 ) head and an Al 2 O 3 liner demonstrated the lowest wear penetration at last follow-up and the lowest rate of wear penetration per year. Additionally, the combination of a crosslinked polyethylene (XLPE) liner and a zircon oxide (ZrO 2 ) head demonstrated the lowest rate of revision at last follow-up. These findings underscore the importance of careful material selection for hip implant bearing surfaces to optimize their longevity and patient satisfaction after THA., (© 2023. The Author(s).)

Introduction: In septic two-stage revision surgery, success depends on numerous factors. Key steps are the procedure of ex- and reimplantation and the choice of spacer in the interim phase. The latter is still a matter of debate. Recently, we showed the microbial non-inferiority of a spacer technique using prosthetic cemented implants with an individualized antibiotic mixture in the cement applying a mechanically inferior cementation method. The aim of the present study was to evaluate the clinical results of these spacers in view of either an endofemoral or a transfemoral procedure., Materials and Methods: Our collective consisted of 86 patients (45 endofemoral and 41 transfemoral procedures). The collective was analyzed with respect to complications, reinfection rate and clinical status at the end of the interim phase. Results of an endofemoral and transfemoral approach were compared., Results: With a median Staffelstein-Score of 60 (range 31-81) at the end of the interim phase, the first clinical results are promising. The reinfection-free rate after a median follow-up of 50 months was 90%. Spacer-related complications occurred in 8% of the total collective. Comparing the endo- and transfemoral procedure, there were no statistical differences in complications or regarding the clinical and infectiological outcome., Conclusions: In this study, we were able to show good clinical results for the presented spacer technique. With no relevant difference in outcome, the decision for an endofemoral or transfemoral technique can be based on technical deliberations. Further prospective comparative studies are necessary to show the clinical benefit of this procedure., (© 2023. The Author(s).)

Purpose: This systematic review evaluated the efficacy and safety of autologous chondrocyte implantation (ACI) for chondral defects of the knee in skeletally immature patients. Current available data from patients reported outcome measures (PROMs) and complications were collected, analyzed, and discussed., Methods: This systematic review was conducted according to the PRISMA guidelines. The following databases were accessed in May 2022: PubMed, Google scholar, Embase, and Scopus. All the clinical studies investigating the efficacy of ACI to manage chondral defects of the knee in skeletally immature patients were accessed. Articles treating patients with surgical procedures other than ACI were not eligible, nor were studies with a follow-up shorter than 12 months., Results: Data from 9 studies (251 procedures) were collected. 32% (80 of 251) of patients were females. The mean length of follow-up was 44.2 ± 29.4 (range, 12-115) months. The mean age of the patients was 16.4 ± 0.7 (range, 15-17) years. The Knee injury and Osteoarthritis Outcome Score (KOOS) and International Knee Document Committee (IKDC) increased of + 41.9/100 (P = 0.003) and + 33.2/100 (P =  < 0.0001) points, respectively. The Lysholm Knee Score improved of + 20.6/100 (P = 0.02) points. The Visual Analogue Scale (VAS) for pain reduced of - 3.6/10 (P = 0.004) points. The Tegner scale did not show any statistically significant improvement from baseline to follow-up (P = n.s.). The rate of graft hypertrophy was 12.5% (5 of 40 patients), and the rate of failure 5.6% (8 of 142 patients)., Conclusion: ACI for chondral defects of the knee is effective to improve PROMs in skeletally immature patients. The safety profile of ACI still remains controversial., Level of Evidence: III., (© 2022. The Author(s).)

Introduction: The management of periprosthetic joint infections (PJI) of the lower limb is challenging, and evidence-based recommendations are lacking. The present clinical investigation characterized the pathogens diagnosed in patients who underwent revision surgery for  PJI of total hip arthroplasty (THA) and total knee arthroplasty (TKA)., Methods: The present study follows the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE). The institutional databases of the RWTH University Medical Centre of Aachen, Germany, were accessed. The OPS (operation and procedure codes) 5-823 and 5-821 and the ICD (International Statistical Classification of Diseases and Related Health Problems) codes T84.5, T84.7 or T84.8 were used. All patients with PJI of a previous THA and TKA who underwent revision surgery were retrieved and included for analysis., Results: Data from 346 patients were collected (181 THAs and 165 TKAs). 44% (152 of 346 patients) were women. Overall, the mean age at operation was 67.8 years, and the mean BMI was 29.2 kg/m2. The mean hospitalization length was 23.5 days. 38% (132 of 346) of patients presented a recurrent infection., Conclusion: PJI remain a frequent cause for revisions after total hip and knee arthroplasty. Preoperative synovial fluid aspiration was positive in 37%, intraoperative microbiology was positive in 85%, and bacteraemia was present in 17% of patients. Septic shock was the major cause of in-hospital mortality. The most common cultured pathogens were Staph. epidermidis, Staph. aureus, Enterococcus faecalis, and Methicillin-resistant Staph aureus (MRSA). An improved understanding of PJI pathogens is important to plan treatment strategies and guide the choice of empirical antibiotic regimens in patients presenting with septic THAs and TKAs., Level of Evidence: Level III, retrospective cohort study., (© 2023. The Author(s).)

Background: After total knee arthroplasty, 10-30% of patients still complain about knee pain, even after exact positioning of the components. Altered knee kinematics are crucial in this regard. The aim of our study was to experimentally determine the influence of different degrees of component coupling of knee prostheses on joint kinematics during muscle-loaded knee flexion in-vitro., Methods: Femoral rollback and femoral rotation of a standard cruciate retaining (GCR), a posterior stabilized (GPS), a rotational hinge (RSL) and a total hinge (SSL) design of the same series of knee replacement implants (SL-series) of one single manufacturer (Waldemar Link GmbH, Hamburg, Germany) were analyzed and set in relation to the motion of the corresponding native knee in a paired study design. All different coupling degrees were analyzed in the same human knees. To simulate muscle loaded knee flexion, a knee simulator was used. Kinematics were measured with an ultrasonic motion capture system and integrated in a calculated coordinate system via CT-imaging., Results: The largest posterior motion on the lateral side was found for the native knee (8.7 ± 7.0 mm), followed by the GPS (3.2 ± 5.1 mm) and GCR (2.8 ± 7.3 mm) implants, while no motion was found for the RSL (0.1 ± 3.0 mm) and the SSL (-0.6 ± 2.7 mm) implants. In contrast, on the medial side, only the native knee showed a posterior motion (2.1 ± 3.2 mm). Regarding femoral external rotation, the only implant where the observed difference did not reach statistical significance when compared to the native knee was the GCR (p = 0.007)., Conclusion: The GCR and GPS kinematics closely imitate those of the native joint. Medial femoral rollback is reduced, however, with the joint pivoting around a rotational center located in the medial plateau. Without additional rotational forces, the coupled RSL and SSL prostheses closely resemble each other with no femoral rollback or relevant rotational component. The femoral axis, however, shifts ventrally in both models when compared with their primary counterparts. The positioning of the coupling mechanism in the femoral and tibial component thus can already lead to altered joint kinematics even in prostheses with an identical surface geometry., (© 2023. The Author(s).)

Malignant melanoma is the most lethal form of skin cancer. Y-box binding protein 1 (YB-1) plays a prominent role in mediating metastatic behavior by promoting epithelial-to-mesenchymal transition (EMT). Migratory melanoma cells exhibit two major migration modes: elongated mesenchymal or rounded amoeboid. Using A375 melanoma cell line and the YB-1 knock-out model, we aimed to elucidate biochemical and biomechanical changes in migration signaling pathways in the context of melanoma metastases. We subjected A375 YB-1 knock-out and parental cells to atomic force microscopy (stiffness determination), immunolabelling, and proteome analysis. We found that YB-1 expressing cells were significantly stiffer compared to the corresponding YB-1 knock-out cell line. Our study demonstrated that the constitutive expression of YB-1 in A375 melanoma cell line appears to be closely related to known biomarkers of epithelial-to-mesenchymal transition, nestin, and vimentin, resulting in a stiffer phenotype, as well as a wide array of proteins involved in RNA, ribosomes, and spliceosomes. YB-1 knock-out resulted in nestin depletion and significantly lower vimentin expression, as well as global upregulation of proteins related to the cytoskeleton and migration. YB-1 knock-out cells demonstrated both morphological features and biochemical drivers of mesenchymal/ameboid migration. Melanoma is a highly plastic, adaptable, and aggressive tumor entity, capable of exhibiting characteristics of different migratory modes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Cykowska, Hofmann, Tiwari, Kosnopfel, Riester and Danalache.)

Purpose: Prior to the COVID-19 pandemic, telemedicine in orthopaedics and trauma surgery had mostly developed for joint arthroplasty, fracture management, and general pre- and postoperative care including teleradiology. With the corona-outbreak, telemedicine was applied on a broad scale to prevent assemblage and to guarantee access to medical care protecting critical areas. The purpose of the present study was to give an overview of the spectrum of clinical applications and the efficacy of telemedicine in orthopaedic and trauma surgery as published in times of the COVID-19 pandemic., Methods: All published studies investigating the application of telemedicine related to orthopaedics and trauma during the COVID-19 pandemic were accessed and screened for suitability. The primary outcome of interest was the efficacy of telemedicine in various clinical applications. The secondary outcome of interest was the spectrum of different applications in which telemedicine applications were investigated., Results: The literature search resulted in 1047 articles. After the removal of duplicates, 894 articles were screened of which 31 finally met the inclusion criteria. Dimensions that were described by studies in the literature to have positive effects were preoperative patient optimisation, the usefulness of telemedicine to correctly diagnose a condition, conservative treatment, willingness to and feasibility for telemedicine in patients and doctors, and postoperative/post-trauma care improvement. The efficacy of telemedicine applications or interventions thereby strongly varied and seemed to depend on the exact study design and the research question addressed., Conclusion: Various successful applications of telemedicine have already been reported in orthopaedics and trauma surgery, with a strong increase in scientific output during the COVID-19 years 2020-2021. Whether the advantages of such an approach will lead to a relevant implementation of telemedicine in everyday clinical practice should be monitored after the COVID-19 pandemic., (© 2023. The Author(s).)

Analogous to articular cartilage, changes in spatial chondrocyte organisation have been proposed to be a strong indicator for local tissue degeneration in the intervertebral disc (IVD). While a progressive structural and functional degradation of the extracellular (ECM) and pericellular (PCM) matrix occurs in osteoarthritic cartilage, these processes have not yet been biomechanically elucidated in the IVD. We aimed to evaluate the local stiffness of the ECM and PCM in the anulus fibrosus of the IVD on the basis of local chondrocyte spatial organisation. Using atomic force microscopy, we measured the Young's modulus of the local ECM and PCM in human and bovine disc samples using the spatial chondrocyte patterns as an image-based biomarker. By measuring tissue from 31 patients and six bovine samples, we found a significant difference in the elastic moduli (E) of the PCM in clusters when compared to the healthy patterns single cells ( p = 0.029), pairs ( p = 0.016), and string-formations ( p = 0.010). The ECM/PCM ratio ranged from 0.62-0.89. Interestingly, in the bovine IVD, the ECM/PCM ratio of the E significantly varied ( p = 0.002) depending on the tissue origin. Overall the reduced E in clusters demonstrates that cluster formation is not only a morphological phenomenon describing disc degeneration, but it marks a compromised biomechanical functioning. Immunohistochemical analyses indicate that collagen type III degradation might be involved. This study is the first to describe and quantify the differences in the E of the ECM in relation to the PCM in the anulus fibrosus of the IVD by means of atomic force microscopy on the basis of spatial chondrocyte organisation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Höflsauer, Bonnaire, Bamberger, Danalache, Feierabend and Hofmann.)

Introduction: The modified Broström operation (MBO) has found widespread use in the therapy of lateral chronic ankle instability (CAI). However, alternative surgical techniques like the open reconstruction using a periosteal flap (RPF) are still an important part of the surgical treatment of lateral CAI. Both procedures differ in terms of the reconstruction material used and the surgical procedure. Comparative studies on the surgical therapy of CAI are limited and generally refer to similar surgical procedures. Aim of this study was to compare the arthroscopic MBO and the RPF., Materials and Methods: We retrospectively analysed 25 patients with lateral CAI after a tear of the anterior talofibular ligament (ATFL). 14 patients received arthroscopic MBO and 11 patients received RPF. We compared the postoperative outcome between both groups with respect to subjective instability, the number of ankle sprains, pain, complications and follow-up operations as well as the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score., Results: Both surgical procedures resulted in a significant improvement in pain, in subjective instability, in the reduction in the frequency of ankle sprains and improvement in the AOFAS ankle-hindfoot score one year postoperatively. Three months postoperatively, the values for pain and instability of the MBO group were significantly better compared to the RPF. One year after the operation, these differences were evened out. Also in terms of complications and follow-up operations, no significant difference was found between the two procedures., Conclusions: Both surgical procedures give very good results one year postoperatively in terms of pain, instability, function and complication rate. With significantly better results regarding pain and instability three months postoperatively, the MBO allows a faster recovery in patients operated with this technique., (© 2021. The Author(s).)

Purpose: This study investigated the impact of the Covid-19 pandemic in Europe on consultations, surgeries, and traumas in the field of orthopaedic and trauma surgery. Strategies to resume the clinical activities were also discussed., Methods: This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses: the 2020 PRISMA statement. All the comparative studies reporting data on the impact of Covid-19 in the field of orthopaedic and trauma surgery in Europe were accessed. Only comparative clinical studies which investigated the year 2020 versus 2019 were eligible., Results: 57 clinical investigations were included in the present study. Eight studies reported a reduction of the orthopaedic consultations, which decreased between 20.9 and 90.1%. Seven studies reported the number of emergency and trauma consultations, which were decreased between 37.7 and 74.2%. Fifteen studies reported information with regard to the reasons for orthopaedic and trauma admissions. The number of polytraumas decreased between 5.6 and 77.1%, fractures between 3.9 and 63.1%. Traffic accidents admissions dropped by up to 88.9%, and sports-related injuries dropped in a range of 59.3% to 100%. The overall reduction of the surgical interventions ranged from 5.4 to 88.8%., Conclusion: The overall trend of consultations, surgeries, and rate of traumas and fragility fractures appear to decrease during the 2020 European COVID pandemic compared to the pre-pandemic era. Given the heterogeneities in the clinical evidence, results from the present study should be considered carefully., Level of Evidence: Level IV, systematic review., (© 2022. The Author(s).)

Introduction: A common reason for painful shoulder arthroplasties and revision surgery is a low-grade periprosthetic joint infection (PJI). Diagnosing a low-grade infection is, however, a major diagnostic challenge. This applies even more to the shoulder, which differs from other large joints in terms of clinical features and microbiological spectrum. Aim of this study was to evaluate the diagnostic value of the synovial biopsy in the diagnostic workup of low-grade PJI of the shoulder., Materials and Methods: A retrospective evaluation was conducted on 56 patients receiving revision surgery on their shoulder arthroplasty. A standardized preoperative workup was performed comprising CRP value, leukocyte blood count, synovial fluid microbiological analyses and leukocyte count from joint aspiration, and five synovial biopsy samples for bacteriologic and histologic analysis obtained through an arthroscopic approach. During revision surgery, five samples of periprosthetic tissue were harvested for bacteriologic and histologic analyses. The MSIS-Criteria 2014 were used to evaluate the diagnostic results., Results: In total, 15 of 56 revised prostheses turned out as PJI (27%). When applying our diagnostic workup, we obtained a sensitivity of 67% with a specificity of 95%. When performing a subgroup analysis on those patients that had received diagnostic biopsy, a sensitivity of 100% and a specificity of 83% could be achieved. With a sensitivity and specificity of 90% and 83%, respectively, the biopsy is the single method with the highest diagnostic value., Conclusions: The sensitivity of only 67% of our standard workup emphasizes the difficulty to adequately diagnose low-grade infections after shoulder arthroplasty. The excellent specificity of 95% ensures, however, that non-infected prostheses are not incorrectly explanted. This study highlights that synovial biopsy has a high diagnostic value and should be done prior to complex revision surgeries to raise sensitivity in diagnosing a PJI., (© 2021. The Author(s).)

Background: Cartilage is a mechanically highly stressed tissue in the human body and an important part of synovial joints. The joint cartilage is lubricated by synovial fluid with hyaluronic acid (HA) as main component. However, in joints with osteoarthritis HA has a lower concentration and molecular weight compared to healthy joints. In recent years, the intra-articular injection of therapeutic HA lubricant, has become a popular therapy. The effect of HA application on the friction of a complete joint with physiological movement needs to be further determined., Methods: The aim of the present study was to evaluate the lubrication effect of the joint by three lubricants (NaCl, fetal calf serum (FCS) and HA) and their effect on the friction in nine complete ovine carpo-metacarpal joints. The joints were mounted on a material testing machine and a physiological movement with 10° rotation was simulated with ascending axial load (100 - 400 N). Specimens were tested native, with cartilage damage caused by drying out and relubricated. Dissipated energy (DE) as a measure of friction was recorded and compared., Results: Investigating the effect of axial load, we found significant differences in DE between all axial load steps (p < .001), however, only for the defect cartilage. Furthermore, we could document an increase in DE from native (Mean: 15.0 mJ/cycle, SD: 8.98) to cartilage damage (M: 74.4 mJ/cycle, SD: 79.02) and a decrease after relubrication to 23.6 mJ/cycle (SD: 18.47). Finally, we compared the DE values for NaCl, FCS and HA. The highest values were detected for NaCl (M Norm  = 16.4 mJ/cycle, SD: 19.14). HA achieved the lowest value (M Norm  = 4.3 mJ/cycle, SD: 4.31), although the gap to FCS (M Norm  = 5.1 mJ/cycle, SD: 7.07) was small., Conclusions: We were able to elucidate three effects in joints with cartilage damage. First, the friction in damaged joints increases significantly compared to native joints. Second, especially in damaged joints, the friction increases significantly more with increased axial load compared to native or relubricated joints. Third, lubricants can achieve an enormous decrease in friction. Comparing different lubricants, our results indicate the highest decrease in friction for HA., (© 2022. The Author(s).)

The diagnostic value of C-reactive protein (CRP) and the serum white blood cell (WBC) count is still barely defined for decision making during septic two-stage revision surgery of hip arthroplasty. We, therefore, compared these values between stages as well as between the groups without and with reinfection in 117 patients. A total of 106 patients were reinfection-free (91%). The median follow-up was 51 months. With a ΔCRP of -10 mg/L and a ΔWBC count of -1000/µL, a significant decrease between stages ( p = 0.001) could be observed. When comparing the CRP and WBC count values between groups, however, no significant difference was found at stage one, stage two and even the difference between these two time points (reinfection-free ΔCRP of -11 mg/L and ΔWBC count of -1000/µL vs. reinfection ΔCRP of -5 mg/L ( p = 0.131) and ΔWBC count of -1100/µL) ( p = 0.424). The diagnostic value was poor for the calculated parameters (area under the curve (AUC) 0.5-0.6). The courses of the mean CRP values of both groups were similar. We conclude that the CRP and WBC count are not helpful to guide the decision making in individual cases.

Bone sarcomas are rare primary malignant mesenchymal bone tumors. The three main entities are osteosarcoma, chondrosarcoma, and Ewing sarcoma. While prognosis has improved for affected patients over the past decades, bone sarcomas are still critical conditions that require an interdisciplinary diagnostic and therapeutic approach. While radiotherapy plays a role especially in Ewing sarcoma and chemotherapy in Ewing sarcoma and osteosarcoma, surgery remains the main pillar of treatment in all three entities. After complete tumor resection, the created bone defects need to be reconstructed. Possible strategies are implantation of allografts or autografts including vascularized bone grafts (e.g., of the fibula). Around the knee joint, rotationplasty can be performed or, as an alternative, the implantation of (expandable) megaprostheses can be performed. Challenges still associated with the implantation of foreign materials are aseptic loosening and infection. Future improvements may come with advances in 3D printing of individualized resection blades/implants, thus also securing safe tumor resection margins while at the same time shortening the required surgical time. Faster osseointegration and lower infection rates may possibly be achieved through more elaborate implant surface structures.

The goal of this study was to compare operative outcomes after lesser toe deformity correction with either proximal interphalangeal (PIP) joint arthrodesis or PIP joint resection arthroplasty. A prospective randomized controlled trial was performed with 37 patients (48 toes) operated on with one of these two procedures. Evaluation of the numeric rating scale score, the American Orthopedic Foot and Ankle Society score, osseous consolidation, and clinical outcome was performed preoperatively and at 6 weeks and 6 months postoperatively. Both study groups showed significant improvement at 6 months postoperatively. Although osseous consolidation was significantly higher for the arthrodesis group ( P =.001), this difference did not affect clinical outcomes, and at 6 months postoperatively, pain on the numeric rating scale was 0 (range, 0-7) for the arthroplasty group and 0 (range, 0-5) for the arthrodesis group ( P =.669). The American Orthopedic Foot and Ankle Society score was 83 (range, 39-95) and 80 (range, 59-95), respectively ( P =.879). No difference was observed for signs of inflammation or axis correction. Even a direct comparison of toes with radiologically osseous fusion (n=16) with those without fusion (n=32) did not show any clinical differences. This randomized controlled study showed no clinical differences in outcome between PIP joint arthrodesis and PIP joint resection arthroplasty for correction of lesser toe deformities, with good to excellent outcomes for both groups. [ Orthopedics . 2022;45(2):86-90.].

Osteoarthritis (OA) is a degenerative joint disease currently affecting half of all women and one-third of all men aged over 65 and it is predicted to even increase in the next decades. In the variety of causes leading to OA, the first common denominator are changes in the extracellular matrix of the cartilage. In later stages, OA affects the whole joint spreading to higher levels of tissue architecture causing irreversible functional and structural damage. To date, the diagnosis of OA is only formulated in the late stages of the disease. This is also, where most present therapies apply. Since a precise diagnosis is a prerequisite for targeted therapy, tools to diagnose early OA, monitor its progression, and accurately stage the disease are wanted. This review article focuses on recent advances in indentation technologies to diagnose early OA through describing biomechanical cartilage characteristics. We provide an overview of microindentation instruments, indentation-type Atomic Force Microscopy, ultrasound, and water-jet ultrasound indentation, Optical Coherence Tomography-based air-jet indentation, as well as fiber Bragg grating., (Copyright © 2022. Published by Elsevier Ltd.)

Background: Targeted infiltrations to the lumbar spine are used to identify the correct scope for surgery in patients with chronic lumbar back pain (CLBP) and multi-segmental pathologies, where radiologic imaging and clinical presentation do not match. Conclusions from that method have so far been based on individual statements of pain relief. The main principle for the infiltrations is the assumption that by locally administering an analgesic agent to possible surgical target areas, the effect of surgery can be temporarily simulated. The aim was to investigate the use of rasterstereographic posture measurements to substantiate reported pain reduction after infiltrations., Methods: In this case-control study (Level II), rasterstereography was performed on 57 patients and 28 reference subjects to evaluate changes in posture during 1 week of injections under fluoroscopic guidance and correlated with changes in the Numeric Pain Rating Scale (NRS). Statistical analysis was performed with SPSS ( α  = .05, two-sided) and presented in the form of box, scatter, and Bland-Altman plots., Results and Conclusion: The CLBP patients' trunk inclination (median 6°) and absolute lateral tilt were significantly increased (p < .01 each) compared to the reference group. No significant difference was observed for trunk length, kyphotic/lordotic angle, or lateral deviation. During infiltration, no significant difference in posture could be observed. A subgroup analysis of patients reporting the highest pain improvement indicated no significant difference. No correlation was observed with pain improvement reported by the patients during injections. Subsequent rasterstereography does not seem to be able to verify results of injections in the diagnostics of lumbar spine pathologies, as patients' reported pain relief does not correlate with a relevant alteration in posture. The short-term effect of the targeted infiltrations may not suffice to change false posture being developed over years., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)