An increased number of neutrophils (NEUs) has long been associated with infections in the knee joints; their contribution to knee osteoarthritis (KOA) pathophysiology remains largely unexplored. This study aimed to compare the phenotypic and functional characteristics of synovial fluid (SF)-derived NEUs in KOA and knee infection (INF). Flow cytometric analysis, protein level measurements (ELISA), NEU oxidative burst assays, detection of NEU phagocytosis (pHrodo. TM. Green Zymosan Biparticles. TM. Conjugate for Phagocytosis), morphological analysis of the SF-derived/synovial tissue NEUs, and cultivation of human umbilical vein endothelial cells (HUVECs) using SF supernatant were used to characterise NEUs functionally/morphologically. Results: Compared with INF NEUs, KOA NEUs were characterised by a lower expression of CD11b, CD54 and CD64, a higher expression of CD62L, TLR2 and TLR4, and lower production of inflammatory mediators and proteases, except CCL2. Functionally, KOA NEUs displayed an increased production of radical oxygen species and phagocytic activity compared with INF NEUs. Morphologically, KOA and INF cells displayed different cell sizes and morphology, histological characteristics of the surrounding synovial tissues and influence on endothelial cells. KOA NEUs were further subdivided into two groups: SF containing <10% and SF with 10%–60% of NEUs. Analyses of two KOA NEU subgroups revealed that NEUs with SF <10% were characterised by 1) higher CD54, CD64, TLR2 and TLR4 expression on their surface; 2) higher concentrations of TNF-α, sTREM-1, VILIP-1, IL-1RA and MMP-9 in SFs. Our findings reveal a key role for NEUs in the pathophysiology of KOA, indicating that these cells are morphologically and functionally different from INF NEUs. Further studies should explore the mechanisms that contribute to the increased number of NEUs and their crosstalk with other immune cells in KOA. This study was supported by the Ministry of Health of the Czech Republic (NU20-06-00269; NU21-06-00370)

Specific and rapid detection methods for spinal tuberculosis, with sufficient sensitivity in HIV-1 co-infected individuals, are needed, to ensure early initiation of appropriate treatment to prevent physical disability and neurological fallout. In addition, understanding the systemic and local pathophysiology of spinal tuberculosis, and its interaction with HIV-1 infection, is crucial to guide future therapeutic interventions. We prospectively enrolled adult patients presenting with signs and symptoms of suspected spinal tuberculosis, at Groote Schuur Hospital, between November 2020 and December 2021. TB diagnostic testing was performed on open and CT-guided spinal biopsies using Xpert MTB/RIF Ultra compared to gold standards TB culture and histology. A highly sensitive droplet digital PCR assay for detecting and quantifying Mycobacterium tuberculosis complex (MTBC) and HIV-1 DNA was tested. Plasma inflammatory proteins were measured to assess systemic inflammation. Xpert Ultra had a high sensitivity of 94.7% and specificity of 100% for STB against TB culture and histology in both open and CT-guided biopsy samples. The ddPCR assay confirmed TB detection in 94% of patients with positive Xpert Ultra results. Four patients with negative TB diagnostic results had MTBC DNA detected by ddPCR. HIV-1 DNA was detected in the spinal tissues from all HIV-1-infected patients. MTBC DNA levels were significantly higher in HIV-1-co-infected spinal tissue samples (p< 0.01). We identified four biomarkers significantly associated with higher bacterial burden at the disease site (p< 0.01). Xpert Ultra and MTBC ddPCR improve the detection of STB. DdPCR can be utilized as an additional, highly sensitive tool for detecting and quantifying Mtb, in pathological samples that may be paucibacillary. These findings provide novel diagnostic and pathophysiologic insight into STB, in the context of HIV-1 infection, and provide rationale to include these tests in hospital and research settings for patients from communities burdened by TB and HIV-1

In approximately 20 years, surgical treatment of femoro-acetabular impingement (FAI) has been widely accepted, and its indications refined. However, the current approach of the disease prevents a good understanding of its pathophysiology, and numerous uncertainties remain. Comprehending inter-individual spine-hip relations (SHRs) can further clarify the pathophysiology of impingement, and explain occasional surprising mismatch between clinical assessment and imaging or intraoperative findings. The rational is simple, the more the spino-pelvic complex is mobile (sagittal ROM) and the more the hip is protected against hip impingement but would probably become at risk of spine-hip syndrome if the spino-pelvic complex comes to degenerate. Grouping patients based on their spine-hip relation can help predict and diagnose hip impingement, and assess the relevance of physiotherapy. With the proposed new classification of FAIs, every patient can be classified in homogeneous groups of complexity of treatment. The primary aim of this paper is to raise awareness of the potential impact that the spine-hip relations have on the hip impingement disease. Two new classifications are proposed, for FAIs and SHRs that can help surgeons in their comprehension, and could be beneficial in clinical and research areas

The pathophysiology of intervertebral disc degeneration has been extensively studied. Various factors have been suggested as influencing its aetiology, including mechanical factors, such as compressive loading, shear stress and vibration, as well as ageing, genetic, systemic and toxic factors, which can lead to degeneration of the disc through biochemical reactions. How are these factors linked? What is their individual importance? There is no clear evidence indicating whether ageing in the presence of repetitive injury or repetitive injury in the absence of ageing plays a greater role in the degenerative process. Mechanical factors can trigger biochemical reactions which, in turn, may promote the normal biological changes of ageing, which can also be accelerated by genetic factors. Degradation of the molecular structure of the disc during ageing renders it more susceptible to superimposed mechanical injuries. This review supports the theory that degeneration of the disc has a complex multifactorial aetiology. Which factors initiate the events in the degenerative cascade is a question that remains unanswered, but most evidence points to an age-related process influenced primarily by mechanical and genetic factors

Shoulder injury related to vaccine administration (SIRVA) is a prolonged episode of shoulder dysfunction that commences within 24 to 48 hours of a vaccination. Symptoms include a combination of shoulder pain, stiffness, and weakness. There has been a recent rapid increase in reported cases of SIRVA within the literature, particularly in adults, and is likely related to the mass vaccination programmes associated with COVID-19 and influenza. The pathophysiology is not certain, but placement of the vaccination in the subdeltoid bursa or other pericapsular tissue has been suggested to result in an inflammatory capsular process. It has been hypothesized that this is associated with a vaccine injection site that is “too high” and predisposes to the development of SIRVA. Nerve conduction studies are routinely normal, but further imaging can reveal deep-deltoid collections, rotator cuff tendinopathy and tears, or subacromial subdeltoid bursitis. However, all of these are common findings within a general asymptomatic population. Medicolegal claims in the UK, based on an incorrect injection site, are unlikely to meet the legal threshold to determine liability. Cite this article: Bone Joint J 2023;105-B(8):839–842

Introduction and Objective

Intervertebral disc (IVD) degeneration is one of the major contributors to low back pain, the leading cause of disability worldwide. This multifactorial pathological process involves the degradation of the extracellular matrix, inflammation, and cell loss due to apoptosis and senescence. While the deterioration of the extracellular matrix and cell loss lead to structural collapse of the IVD, increased levels of inflammation result in innervation and the development of pain. Amongst the known regulators of inflammation, toll-like receptors (TLRs) and more specifically TLR-2 have been shown to be specifically relevant in IVD degeneration. As strong post-transcriptional regulators, microRNAs (miRNAs) and their dysregulation has been connected to multiple pathologies, including degenerative diseases such as osteoarthritis and IVD degeneration. However, the role of miRNAs in TLR signalling in the IVD is still poorly understood and was hence investigated in this study.

Aims. This study explored the shared genetic traits and molecular interactions between postmenopausal osteoporosis (POMP) and sarcopenia, both of which substantially degrade elderly health and quality of life. We hypothesized that these motor system diseases overlap in pathophysiology and regulatory mechanisms. Methods. We analyzed microarray data from the Gene Expression Omnibus (GEO) database using weighted gene co-expression network analysis (WGCNA), machine learning, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis to identify common genetic factors between POMP and sarcopenia. Further validation was done via differential gene expression in a new cohort. Single-cell analysis identified high expression cell subsets, with mononuclear macrophages in osteoporosis and muscle stem cells in sarcopenia, among others. A competitive endogenous RNA network suggested regulatory elements for these genes. Results. Signal transducer and activator of transcription 3 (STAT3) was notably expressed in both conditions. Single-cell analysis pinpointed specific cells with high STAT3 expression, and microRNA (miRNA)-125a-5p emerged as a potential regulator. Experiments confirmed the crucial role of STAT3 in osteoclast differentiation and muscle proliferation. Conclusion. STAT3 has emerged as a key gene in both POMP and sarcopenia. This insight positions STAT3 as a potential common therapeutic target, possibly improving management strategies for these age-related diseases. Cite this article: Bone Joint Res 2024;13(8):411–426

Total joint arthroplasty is the most significant advance in the treatment of end-stage arthritic disease of major joints. Despite the clinical success of this surgical procedure, however, some total joint prostheses fail, and although a failed prosthesis can be replaced, the results of revision arthroplasty are not as good as the first time. Studying the failed prosthesis and the associated bone and soft tissues provides insight into the causes of failure.

Most prosthetic failures are the result of structural limitations of the implant components. Although material failure may be sudden, a much more common cause is gradual aseptic loosening of the prostheses. Aseptic loosening is caused by both mechanical (gradual loss of material by wear) and biological (osteoclastic resorption of adjacent bone) factors. Wear particles induce a foreign body reaction characterized by a pseudomembrane composed of granulomatous tissues including macrophages, fibroblasts, giant cells, and osteoclasts in addition to debris particles. The extent of this response is driven by the number, size, composition, surface area, and types of particles present. Although there are differences in the relative local toxicity of each of these particles, the end result is the same. These mechanical and biological factors are unavoidable, and the success of a total joint prosthesis depends on the rate with which they occur. Polyethylene wear particles (1–200 ?) are the primary cause of loosening. They are strongly birefringent under polarized light microscopy. Smaller particles are phagocytized by histiocytes, whereas larger particles are surrounded by foreign body giant cells. Fragmentation of PMMA may also cause particulate debris. The presence of these particles (30–100 ?) may be deduced by empty spaces into the soft tissues, often bordered by foreign body giant cells, since PMMA is dissolved by xylene during routine histological techniques. Metal oxides form on the surface of chrome-cobalt or titanium alloys due to an electrolytic process, and stresses on the surface of the metal shear the oxides into the surrounding tissues, causing a black pigmentation of the tissues. Histologically, the black deposits of oxidized metals are seen extracellularly as well as in the cytoplasm of histiocytes. In addition to oxidation, metal undergoes corrosion and, as a result, metal ions enter the soft tissues and the bloodstream. A ceramic-on-ceramic coupling generates a significantly lower amount of debris as compared to the conventional metal-on polyethylene solution. When present, ceramic debris cause a mild histiocytic reaction without giant cells and virtually no osteoclastic bone resorption. There are various secretory proteins at the interfacial membrane that can affect bone turnover, including the cytokines IL-1, IL-6, Il-10, and TNF-a. Other factors involved with bone resorption include the enzymes responsible for catabolism of the organic component of bone, such as MMPs. Prostaglandins, in particular PGE2, are also known to be important intercellular messengers in the osteolytic cascade. More recently, several mediators known to be involved in stimulation or inhibition of osteoclast differentiation and maturation, such as RANKL and osteoprotegerin, have been suggested as key factors in the development and progression of osteolysis.

Infection around a prosthesis also causes loosening in approximately 1–5% of cases. Total joint prostheses become infected by two mechanisms, wound contamination at the time of surgery by Staph. aureus or Staph.epidermidis, and late hematogenous spread of organisms (Staphylo- and Streptococci, E. Coli, Pseudomonas, and anaerobes). The following factors facilitate bacterial growth. First, reaming and sawing, as well as PMMA polymerization, cause necrosis of necrotize bone adjacent to the implant, and such nonvascularized area permits bacteria to grow, safe from circulating host defenses. Second, a highly hydrated matrix of extracellular polymeric substances (biofilm) is formed that defends bacteria from antibiotics and phagocytosis. Third, some metals, such as nickel or cobalt, may depress macrophage function. The distinguishing histologic features of an infected prosthesis is an acute inflammatory reaction: a finding of > 5 PMN or of > 50 lymphocytes/hp field are presumptive for infection. Because some low-grade infections fail to stimulate an acute inflammatory reaction, they go undiagnosed until postoperative period when microbacterial culture results are available. To date, no single routinely used clinical or laboratory test has been shown to achieve ideal sensitivity and specificity for the diagnosis of prosthetic joint infection, and in most cases the diagnosis depends on a combination of clinical features, radiographic findings, and laboratory results. Intra-operative tissue cultures may be falsely negative because of prior antimicrobial exposure, a low number of organisms, inappropriate culture media, or atypical organisms. Conversely, cultures may be falsely positive because of contamination in the operating room, during transport, or in the laboratory. If the implant is removed, the entire prosthesis can be cultured. Moreover, because prosthetic joint infection is a biofilm-mediated infection, techniques that sample bacteria in biofilm, such as sonication or enzymatic treatment, may improve the diagnosis of prosthetic joint infection. More recently, molecular techniques are being used to detect nucleic acid in samples from infected patients even when conventional techniques are negative because of unusual microbial growth requirements or failure to grow after antimicrobial exposure or due to unfavourable environmental conditions. A disadvantage of such approach is its extreme sensitivity, leading to the possibility of false positive results.

The clinical presentation of prosthetic joint infection may be indistinguishable from that of aseptic implant failure. In many cases, culture of granulomatous tissue around failed prostheses, preoperatively diagnosed as aseptically loosened, reveals the presence of bacteria that may per se significantly contribute to the recruitment, maturation and activation of osteoclasts and that superimpose to the foreign body reaction to wear debris. The presence of a smouldering infection in case of “aseptic” failure observed in revision arthroplasties. A systematic investigation on all retrieved implants is mandatory to define the precise role of each potential factor contributing to the pathogenesis of failure, in order to further improve the quality of care of patients having total joint arthroplasty.

The paramount importance of synovial fluid in lubrication and protection of articular joints has long been recognized. Synovial fluid, a dialysate of plasma, forms an interface with both the synovium and cartilage and plays a crucial role in joint lubrication and bearing functions. In an osteoarthritic joint, damage to the articular cartilage causes modifications in the rheological properties of synovial fluid and, reducing the viscoelasticity and increasing the friction between articular surfaces. Viscosupplementation is a treatment for osteoarthritis that uses hyaluronic acid as a (visco)supplement to the diseased joint. The aim of this treatment is to restore the rheological properties of synovial fluid. Osteoarthritis is the most common disease affecting the joints in human population and among the most important causes of pain, disability and economic loss. Therefore, innovative methods are needed to more effectively treat osteoarthritis, directly addressing the disease process. Among various locomotor mechanisms that could serve to illustrate the integrated nature of functional morphology, perhaps none is more complex than the equine locomotor system.

Confronting the need for evaluating the current methods to control joint disease, the horse provides an excellent animal model. As it suffers similar clinical manifestations to those seen in human, it may provide tentative biomedical extrapolations.

Eleven patients with arthrogryposis multiplex congenita neurologica have been reviewed. Distinct patterns of deformity and muscle activity were identified which have been correlated with specific levels of segmental neurological motor deficit without sensory loss. The clinical picture was consistent with localised lesions of the anterior horn cell cell columns. This finding agreed with the recorded pathological lesions. Orthopaedic treatment should take account of the paralytic nature of the deformities.

Cite this article: Bone Joint Res 2022;11(8):514–517.

Avascular necrosis is poorly understood. The etiological factors have not been fully delineated. This disease process had a huge cost impact on the health system due to surgical treatment. Patients with avascular necrosis seen at a single institution underwent DNA extraction and analysis, coagulation-related analysis and buccal smears with DNA analysis. In this patient group 60% tested positive for at least one thrombophilic or hypofibrinolysis factor. We make recommendations depending on the defect in the cascade, allowing for potential non-surgical management of osteonecrosis in patients undergoing therapy with known antagonistic medications (i.e. corticosteroids).

The etiology and pathogenesis of nontraumatic AVN need to be better elucidated.

Our study identifies the potential association of thrombophilic and hypofibrinolytic factors and osteonecrosis of the hip, particularly genetic markers as identified through DNA markers

The significance of this study:

Osteonecrosis is a devastating musculoskeletal condition;

60% of patients had at least one tested thrombophilic or hypofibrinolysis factor positive. Most patients never had a thrombotic event.

Genetic screening, multiple hematological paramteres were tested on patients with avascular necrosis.

hypercoagulability plays a role in the development of AVN of the hip, mainly at the microvascular level;

Vascular inflammation and activation of myofibroblasts are significant contributors to the progression of fibrosis, which can severely impair tissue function. In various tissues, including tendons, Transforming growth factor beta 1 (TGF-β1) has been identified as a critical driver of adhesion and scar formation. Nevertheless, the mechanisms that underlie fibrotic peritendinous adhesions are still not well comprehended, and human microphysiological systems to help identify effective therapies remain scarce. To address this issue, we developed a novel human Tendon-on-a-Chip (hToC), comprised of an endothelialized vascular compartment harboring circulating monocytes and separated by a 5 μm/100 nm dual-scale ultrathin porous membrane from a type I/III collagen hydrogel with primary tendon fibroblasts and tissue-resident macrophages, all under defined serum-free conditions. The hToC models the crosstalk of the various cells in the system leading to the induction of inflammatory and fibrotic pathways including the activation of mTOR signaling. Consistent with phenotypes observed in vivo in mouse models and clinical human samples, we observed myofibroblast differentiation and senescence, tissue contraction, excessive extracellular matrix deposition, and monocytes’ transmigration and macrophages’ secretion of inflammatory cytokines, which were dependent on the presence of the endothelial barrier. This model offers novel insights on the role of vasculature in the pathophysiology of adhesions, which were previously underappreciated. Moreover, in testing whether the hToC could be used to evaluate efficacy of therapeutics, we were able to capture donor-specific variability in the response to Rapamycin treatment, which reduced myofibroblast activation regardless. Thus, our findings demonstrate the value of the hToC as a human microphysiological system for investigating the pathophysiology of fibrotic conditions in the context of peritendinous injury and similar fibrotic conditions, providing an alternative to animal testing

Tendinopathy can commonly occur around the foot and ankle resulting in isolated rupture, debilitating pain and degenerative foot deformity. The pathophysiology and key cells involved are not fully understood. This is partly because the dense collagen matrix that surrounds relatively few resident cells limits the ability of previous techniques to identify and target those cells of interest. In this study, we apply novel single cell RNA sequencing (CITE-Seq) techniques to healthy and tendinopathic foot/ankle tendons. For the first time we have identified multiple sub-populations of cells in human tendons. These findings challenge the view that there is a single principal tendon cell type and open new avenues for further study. Healthy tendon samples were obtained from patients undergoing tendon transfer procedures; including tibialis posterior and FHL. Diseased tendon samples were obtained during debridement of intractable Achilles and peroneal tendinopathy, and during fusion of degenerative joints. Single cell RNA sequencing with surface proteomic analysis identified 10 sub-populations of human tendon derived cells. These included groups expressing genes associated with fibro-adipogenic progenitors (FAPs) as well as ITGA7+VCAM1- recently described in mouse muscle but, as yet, not human tendon. In addition we have identified previously unrecognised sub-classes of collagen type 1 associated tendon cells. Each sub-class expresses a different set of extra-cellular matrix genes suggesting they each play a unique role in maintaining the structural integrity of normal tendon. Diseased tendon harboured a greater proportion of macrophages and cytotoxic lymphocytes than healthy tendon. This inflammatory response is potentially driven by resident tendon fibroblasts which show increased expression of pro-inflammatory cytokines. Finally, identification of a previously unknown sub-population of cells found predominantly in tendinopathic tissue offers new insight into the underlying pathophysiology. Further work aims to identify novel proteins targets for possible therapeutic pathways

Aims. Children with spinal dysraphism can develop various musculoskeletal deformities, necessitating a range of orthopaedic interventions, causing significant morbidity, and making considerable demands on resources. This systematic review aimed to identify what outcome measures have been reported in the literature for children with spinal dysraphism who undergo orthopaedic interventions involving the lower limbs. Methods. A PROSPERO-registered systematic literature review was performed following PRISMA guidelines. All relevant studies published until January 2023 were identified. Individual outcomes and outcome measurement tools were extracted verbatim. The measurement tools were assessed for reliability and validity, and all outcomes were grouped according to the Outcome Measures Recommended for use in Randomized Clinical Trials (OMERACT) filters. Results. From 91 eligible studies, 27 individual outcomes were identified, including those related to clinical assessment (n = 12), mobility (n = 4), adverse events (n = 6), investigations (n = 4), and miscellaneous (n = 1). Ten outcome measurement tools were identified, of which Hoffer’s Functional Ambulation Scale was the most commonly used. Several studies used unvalidated measurement tools originally developed for other conditions, and 26 studies developed new measurement tools. On the OMERACT filter, most outcomes reported pathophysiology and/or the impact on life. There were only six patient- or parent-reported outcomes, and none assessed the quality of life. Conclusion. The outcomes that were reported were heterogenous, lack validation and failed to incorporate patient or family perceptions. Until outcomes can be reported unequivocally, research in this area will remain limited. Our findings should guide the development of a core outcome set, which will allow consistency in the reporting of outcomes for this condition. Cite this article: Bone Joint J 2024;106-B(3):277–285

Aims. Osteoarthritis (OA) is a common degenerative joint disease worldwide, which is characterized by articular cartilage lesions. With more understanding of the disease, OA is considered to be a disorder of the whole joint. However, molecular communication within and between tissues during the disease process is still unclear. In this study, we used transcriptome data to reveal crosstalk between different tissues in OA. Methods. We used four groups of transcription profiles acquired from the Gene Expression Omnibus database, including articular cartilage, meniscus, synovium, and subchondral bone, to screen differentially expressed genes during OA. Potential crosstalk between tissues was depicted by ligand-receptor pairs. Results. During OA, there were 626, 97, 1,060, and 2,330 differentially expressed genes in articular cartilage, meniscus, synovium, and subchondral bone, respectively. Gene Ontology enrichment revealed that these genes were enriched in extracellular matrix and structure organization, ossification, neutrophil degranulation, and activation at different degrees. Through ligand-receptor pairing and proteome of OA synovial fluid, we predicted ligand-receptor interactions and constructed a crosstalk atlas of the whole joint. Several interactions were reproduced by transwell experiment in chondrocytes and synovial cells, including TNC-NT5E, TNC-SDC4, FN1-ITGA5, and FN1-NT5E. After lipopolysaccharide (LPS) or interleukin (IL)-1β stimulation, the ligand expression of chondrocytes and synovial cells was upregulated, and corresponding receptors of co-culture cells were also upregulated. Conclusion. Each tissue displayed a different expression pattern in transcriptome, demonstrating their specific roles in OA. We highlighted tissue molecular crosstalk through ligand-receptor pairs in OA pathophysiology, and generated a crosstalk atlas. Strategies to interfere with these candidate ligands and receptors may help to discover molecular targets for future OA therapy. Cite this article: Bone Joint Res 2022;11(12):862–872

Imaging can provide valuable information about the function of tissues and organs. The capacity for detecting and measuring imaging biomarkers of biological activities, allows for a better understanding of the pathophysiology of any process in the human body, including the musculoskeletal system. This is of particular importance in oncologic, metabolic and rheumatologic diseases, but not limited to these. In the domain of the musculoskeletal system, functional imaging also means to be able to address biomechanical evaluations. Weight-bearing imaging and dynamic studies have a prominent role. All imaging techniques (X-rays, CT, MR, ultrasound) are in demand, and offer different applications, specific equipment and novel methods for addressing this. Functional imaging is also essential to drive minimally invasive treatments – i.e. interventional radiology, and new treatment approaches move together with the advances on imaging guidance methods. On both the diagnostic and the interventional side, the increasing availability of dedicated equipment and the development of specific imaging methods and protocols greatly helps the transition from research to clinical practice

The pathophysiological basis of alterations in trabecular bone of patients with osteonecrosis of the femoral head (ONFH) remains unclear. ONFH has classically been considered a vascular disease with secondary changes in the subchondral bone. However, there is increasing evidence suggesting that ONFH could be a bone disease, since alterations in the functionality of bone tissue distant from the necrotic lesion have been observed. We comparatively studied the transcriptomic profile of trabecular bone obtained from the intertrochanteric region of patients with ONFH without an obvious aetiological factor, and patients with osteoarthritis (OA) undergoing total hip replacement in our Institution. To explore the biological processes that could be affected by ONFH, we compared the transcriptomic profile of trabecular bone from the intertrochanteric region and the femoral head of patients affected by this condition. Differential gene expression was studied using an Affymetrix microarray platform. Transcriptome analysis showed a differential signature in trabecular bone from the intertrochanteric region between patients with ONFH and those with OA. The gene ontology analyses of the genes overexpressed in bone tissue of patients with ONFH revealed a range of enriched biological processes related to cell adhesion and migration and angiogenesis. In contrast, most downregulated transcripts were involved in cell division. Trabecular bone in the intertrochanteric region and in the femoral head also exhibited a differential expression profile. Among the genes differentially expressed, we highlighted those related with cytokine production and immune response. This study identified a set of differently expressed genes in trabecular bone of patients with idiopathic ONFH, which might underlie the pathophysiology of this condition. Acknowledgements: This work was supported by grants PI18/00643 and PI22/00939 from ISCIII-FEDER, Ministerio de Ciencia, Innovación y Universidades (MICINN)-AES

The aim of this study was to examine the incidence of obesity in patients undergoing primary total shoulder replacement (TSR) (stemmed and reverse) for osteoarthritis (OA) in Australia compared to the incidence of obesity in the general population. A 2017–18 cohort of 2,621 patients from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) who underwent TSR, were compared with matched controls from the Australian Bureau of Statistics (ABS) National Health Survey from the same period. The two groups were analysed according to BMI category, sex and age. According to the 2017–18 National Health Survey, 35.6% of Australian adults are overweight and 31.3% are obese. Of the primary TSR cases performed, 34.2% were overweight and 28.6% were obese. The relative risk of requiring TSR for OA increased with increasing BMI category. Class-3 obese females, aged 55–64, were 8.9 times more likely to require TSR compared to normal weight counterparts. Males in the same age and BMI category were 2.5 times more likely. Class-3 obese patients underwent TSR 4 years (female) and 7 years (male) sooner than their normal weight counterparts. Our findings suggest that the obese population is at risk for early and more frequent TSR for OA. Previous studies demonstrate that obese patients undergoing TSR also exhibit increased risks of longer operative times, higher superficial infection rates, higher periprosthetic fracture rates, significantly reduced post-operative forward flexion range and greater revision rates. Obesity significantly increases the risk of requiring TSR. To our knowledge this is the first study to publish data pertaining to age and BMI stratification of TSR Societal efforts are vital to diminish the prevalence and burden of obesity related TSR. There may well be reversible pathophysiology in the obese population to address prior to surgery (adipokines, leptin, NMDA receptor upregulation). Surgery occurs due to recalcitrant or increased pain despite non-op Mx

Osteoporosis can cause significant disability and cost to health services globally. We aim to compare risk fractures for both osteoporosis and fractures at the L1-L4 vertebrae (LV) and the neck of femurs (NOFs) in patients referred for DEXA scan in the North-West of England. Data was obtained from 31546 patients referred for DEXA scan in the North-West of England between 2004 and 2011. Demographic data was retrospectively analysed using STATA, utilising chi-squared and t-tests. Logistical models were used to report odds ratios for risk factors included in the FRAX tool looking for differences between osteoporosis and fracture risk at the LV and NOFs. In a study involving 2530 cases of LV fractures and 1363 of NOF fractures, age was significantly linked to fractures and osteoporosis at both sites, with a higher risk of osteoporosis at NOFs compared to LV. Height provided protection against fractures and osteoporosis at both sites, with a more pronounced protective effect against osteoporosis at NOFs. Weight was more protective for NOF fractures, while smoking increased osteoporosis risk with no site-specific difference. Steroids were unexpectedly protective for fractures at both sites, with no significant difference, while alcohol consumption was protective against osteoporosis at both sites and associated with increased LV fracture risk. Rheumatoid arthritis increased osteoporosis risk in NOFs and implied a higher fracture risk, though not statistically significant compared to LV. Results summarised in Table 1. Our study reveals that established osteoporosis and fracture risk factors impact distinct bony sites differently. Age and rheumatoid arthritis increase osteoporosis risk more at NOFs than LV, while height and steroids provide greater protection at NOFs. Height significantly protects LV fractures, with alcohol predicting them. Further research is needed to explore risk factors’ impact on additional bony sites and understand the observed differences’ pathophysiology. For any figures or tables, please contact the authors directly

Aims. The increase in prescription opioid misuse and dependence is now a public health crisis in the UK. It is recognized as a whole-person problem that involves both the medical and the psychosocial needs of patients. Analyzing aspects of pathophysiology, emotional health, and social wellbeing associated with persistent opioid use after injury may inform safe and effective alleviation of pain while minimizing risk of misuse or dependence. Our objectives were to investigate patient factors associated with opioid use two to four weeks and six to nine months after an upper limb fracture. Methods. A total of 734 patients recovering from an isolated upper limb fracture were recruited in this study. Opioid prescription was documented retrospectively for the period preceding the injury, and prospectively at the two- to four-week post-injury visit and six- to nine-month post-injury visit. Bivariate and multivariate analysis sought factors associated with opioid prescription from demographics, injury-specific data, Patient Reported Outcome Measurement Instrumentation System (PROMIS), Depression computer adaptive test (CAT), PROMIS Anxiety CAT, PROMIS Instrumental Support CAT, the Pain Catastrophizing Scale (PCS), the Pain Self-efficacy Questionnaire (PSEQ-2), Tampa Scale for Kinesiophobia (TSK-11), and measures that investigate levels of social support. Results. A new prescription of opioids two to four weeks after injury was independently associated with less social support (odds ratio (OR) 0.26, p < 0.001), less instrumental support (OR 0.91, p < 0.001), and greater symptoms of anxiety (OR 1.1, p < 0.001). A new prescription of opioids six to nine months after injury was independently associated with less instrumental support (OR 0.9, p < 0.001) and greater symptoms of anxiety (OR 1.1, p < 0.001). Conclusion. This study demonstrates that potentially modifiable psychosocial factors are associated with increased acute and chronic opioid prescriptions following upper limb fracture. Surgeons prescribing opioids for upper limb fractures should be made aware of the screening and management of emotional and social health. Cite this article: Bone Jt Open 2021;2(2):119–124

In the past decades, a huge amount of effort has been devoted to translate evidence based on standard preclinical models of bone tumours to effective tools for clinical applications. Although cancer is a genetic disease, hence the emphasis on -omics approaches, the complexity of cancer tissue, a mix of competing clones of transformed elements that react differently to microenvironmental stimuli, may hardly be reproduced by standard approaches. Cost, biological differences and ethical concerns are increasingly recognized as weaknessess of animal models. To overcome these limitations and provide reliable, reproducible, and affordable tools for predicting the effectiveness of treatments, environmental-controlled 3D cultures and co-cultures (spheroids, organoids) coupled with microfluidics and advanced imaging have recently being considered as effective instrument to increase knowledge on the pathophysiology of bone tumours and define effective therapeutic solutions

Osteogenesis Imperfecta (OI) is a heritable bone disorder characterized by bone fragility and often caused by mutations in the Type I collagen-encoding genes COL1A1 and COL1A2. The pathophysiology of OI, particularly at the cellular level, is still not well understood. This contributes to the lack of a cure for this disorder as well as an effective preventive or management options of its complications. In the bone environment, mesenchymal stem cells (MSCs) and osteoblasts (Ob) exert their function, at least partially, through the secretion of extracellular vesicles (EV). EV is a heterogeneous group of nanosized membrane-enclosed vesicles that carry/transfer a cargo of proteins, lipid and nucleic acids from the secreting cell to its target cells. Our objective is to characterize EVs secreted by human control (HC)- and OI-MSCs and their derived Obs, with focus on their protein content. We hypothesize that there will be differences in the protein content of EVs secreted by OI-Obs compared to HC-Ob, which may indicate a deviation from healthy Ob behavior and, thus, a role in OI pathophysiology. MSCs were harvested from the adipose tissue of four COL1A1-OI and two HC patients. They were proliferated in an EV-depleted media, then induced to differentiate to extracellular matrix (ECM)-producing osteoblasts, which then gets mineralized. EVs secreted by MSCs (MSC-EV) and Obs (Ob-EV) were then purified and concentrated. Using liquid chromatography- tandem mass spectrometry, proteomic analysis of the EV groups was done. A total of 384 unique proteins were identified in all EVs, 373 were found in Vesiclepedia indicating a good enrichment of our samples with EV proteins. 67 proteins of the total 384 were exclusively or significantly upregulated (p-value < 0 .05) in OI-Ob-EV and 28 proteins in the HC-Ob-EVs, relative to each other. These two groups of differentially expressed proteins were compared by Gene Ontology (GO) analysis of their cellular compartment, molecular functions and biological processes. We observed that there were differences in the cellular origin of EV-proteins, which may indicate heterogeneity of the isolated EVs. Molecular function and biological process analyses of the HC-Ob-EV proteins showed, as expected, predominantly calcium-related activities such as extracellular matrix (ECM) mineralization. OI-Ob-EV proteins were still predominantly exhibiting ECM organization and formation functions. Annexins A1,2,4,5 and 6 were differentially and significantly upregulated by the HC-Ob-EVs. Fibronectin (FN), Fibulin-1 and −2, and Laminins (α4 & γ1), which are amongst the early non-collagenous proteins to form the ECM, were differentially and significantly upregulated in the OI-Ob-EVs. We concluded that the persistent expression of Fibronectin (FN), Fibulin-1 and −2, and Laminins in OI-Ob-EVs might indicate the presence of an immature ECM that the OI-Obs are trying to organize. ECM mineralization is largely dependent on the presence of an organized mature ECM, and this being compromised in OI bone environment, may be a contributor to the bone fragility seen in these patients. Annexins, which are calcium-binders that are vital for ECM mineralization, were significantly downregulated in the OI-Ob-EVs and this may be a further contributor to ECM mineralization impairment and bone fragility

Breast cancer is the most frequent malignancy in women with an estimation of 2.1 million new diagnoses in 2018. Even though primary tumours are usually efficiently removed by surgery, 20–40% of patients will develop metastases in distant organs. Bone is one of the most frequent site of metastases from advanced breast cancer, accounting from 55 to 58% of all metastases. Currently, none of the therapeutic strategies used to manage breast cancer bone metastasis are really curative. Tailoring a suitable model to study and evaluate the disease pathophysiology and novel advanced therapies is one of the major challenges that will predict more effectively and efficiently the clinical response. Preclinical traditional models have been largely used as they can provide standardization and simplicity, moreover, further advancements have been made with 3D cultures, by spheroids and artificial matrices, patient derived xenografts and microfluidics. Despite these models recapitulate numerous aspects of tumour complexity, they do not completely mimic the clinical native microenvironment. Thus, to fulfil this need, in our study we developed a new, advanced and alternative model of human breast cancer bone metastasis as potential biologic assay for cancer research. The study involved breast cancer bone metastasis samples obtained from three female patients undergoing wide spinal decompression and stabilization through a posterior approach. Samples were cultured in a TubeSpin Bioreactor on a rolling apparatus under hypoxic conditions at time 0 and for up to 40 days and evaluated for viability by the Alamar Blue test, gene expression profile, histology and immunohistochemistry. Results showed the maintenance and preservation, at time 0 and after 40 days of culture, of the tissue viability, biological activity, as well as molecular markers, i.e. several key genes involved in the complex interactions between the tumour cells and bone able to drive cancer progression, cancer aggressiveness and metastasis to bone. A good tis sue morphological and microarchitectural preservation with the presence of lacunar osteolysis, fragmented trabeculae locally surrounded by osteoclast cells and malignant cells and an intense infiltration by tumour cells in bone marrow compartment in all examined samples. Histomorphometrical data on the levels of bone resorption and bone apposition parameters remained constant between T0 and T40 for all analysed patients. Additionally, immunohistochemistry showed homogeneous expression and location of CDH1, CDH2, KRT8, KRT18, Ki67, CASP3, ESR1, CD8 and CD68 between T0 and T40, thus further confirming the invasive behaviour of breast cancer cells and indicating the maintaining of the metastatic microenvironment. The novel tissue culture, set-up in this study, has significant advantages in comparison to the pre-existent 3D models: the tumour environment is the same of the clinical scenario, including all cell types as well as the native extracellular matrix; it can be quickly set-up employing only small samples of breast cancer bone metastasis tissue in a simple, ethically correct and cost-effective manner; it bypasses and/or decreases the necessity to use more complex preclinical model, thus reducing the ethical burden following the guiding principles aimed at replacing/reducing/refining (3R) animal use and their suffering for scientific purposes; it can allow the study of the interactions within the breast cancer bone metastasis tissue over a relatively long period of up to 40 days, preserving the tumour morphology and architecture and allowing also the evaluation of different biological factors, parameters and activities. Therefore, the study provides for the first time the feasibility and rationale for the use of a human-derived advanced alternative model for cancer research and testing of drugs and innovative strategies, taking into account patient individual characteristics and specific tumour subtypes so predicting patient specific responses

Recently, the use of metal-on-metal articulations in total hip arthroplasty (THA) has led to an increase in adverse events owing to local soft-tissue reactions from metal ions and wear debris. While the majority of these implants perform well, it has been increasingly recognised that a small proportion of patients may develop complications secondary to systemic cobalt toxicity when these implants fail. However, distinguishing true toxicity from benign elevations in cobalt ion levels can be challenging. . The purpose of this two part series is to review the use of cobalt alloys in THA and to highlight the following related topics of interest: mechanisms of cobalt ion release and their measurement, definitions of pathological cobalt ion levels, and the pathophysiology, risk factors and treatment of cobalt toxicity. Historically, these metal-on-metal arthroplasties are composed of a chromium-cobalt articulation. . The release of cobalt is due to the mechanical and oxidative stresses placed on the prosthetic joint. It exerts its pathological effects through direct cellular toxicity. . This manuscript will highlight the pathophysiology of cobalt toxicity in patients with metal-on-metal hip arthroplasties. Take home message: Patients with new or evolving hip symptoms with a prior history of THA warrant orthopaedic surgical evaluation. Increased awareness of the range of systemic symptoms associated with cobalt toxicity, coupled with prompt orthopaedic intervention, may forestall the development of further complications. Cite this article: Bone Joint J 2016;98-B:6–13

OA pathophysiology has a vascular component consisting of venous stasis resulting in intraosseous hypertension and hypoxia. In response, osteoblasts change their cytokine expression, accelerating bone remodelling and cartilage breakdown consistent with OA. We have characterized circulatory kinetics in OA bone in animal models with dynamic contrast enhanced MRI (DCE-MRI) and . 18. F PET and have demonstrated venous stasis and reduced perfusion that temporally precede and spatially coincide with OA lesions. Osteoblast uptake of . 18. F is consistent with abnormal perfusion, bone remodelling, and severity of OA. Circulatory kinetics with DCE-MRI in humans with OA of the knee exhibit similar venous outflow obstruction. Venous stasis is associated with hypoxia in subchondral bone. As an example of the effects of hypoxia on OA osteoblasts, we have described upregulation of fibrinolytic peptides, but a deficiency in the upregulation of PAI-1, leading to the generation of plasmin by human OA osteoblasts exposed to hypoxia in vitro. Plasmin is a serine protease that has been shown to degrade cartilage in OA. Abnormal circulatory kinetics by DCE-MRI may be an imaging biomarker of OA. Pharmacologic modulation of venous stasis would have a salutary effect on the physicochemical microcirculation of subchondral osteoblasts and the pathophysiology of OA

Evaluating musculoskeletal conditions of the lower limb and understanding the pathophysiology of complex bone kinematics is challenging. Static images do not take into account the dynamic component of relative bone motion and muscle activation. Fluoroscopy and dynamic MRI have important limitations. Dynamic CT (4D-CT) is an emerging alternative that combines high spatial and temporal resolution, with an increased availability in clinical practice. 4D-CT allows simultaneous visualization of bone morphology and joint kinematics. This unique combination makes it an ideal tool to evaluate functional disorders of the musculoskeletal system. In the lower limb, 4D-CT has been used to diagnose femoroacetabular impingement, patellofemoral, ankle and subtalar joint instability, or reduced range of motion. 4D-CT has also been used to demonstrate the effect of surgery, mainly on patellar instability. 4D-CT will need further research and validation before it can be widely used in clinical practice. We believe, however, it is here to stay, and will become a reference in the diagnosis of lower limb conditions and the evaluation of treatment options. Cite this article: Bone Joint J 2021;103-B(5):822–827

Introduction. Missile injuries are very serious injuries particularly in the cervical region. They are classified into high and low missile injuries when it involves the cervical spine. In modern guerrilla warfare, one must be aware of ballistic pathology with bullets as well as from explosives. In particular, improvised explosive devices commonly known as IED's play a new and important pathophysiology whether they are suicided vests or roadside bombs. They usually produce severe or lethal injuries and serious neurovascular deficit is frequent. We present the details of 40 patients with local experience on how to handle serious penetrating cervical missile injuries. Methods. All cases were collected from the record of Basrah University Hospital, Iraq. Healthy military gentlemen with ages ranging between 20–35 years were included. Results. 11 patients had bullet injuries and 29patients had fragments of shell injuries. The sites of injuries were 9: C2–C3, 12: C5–C6, 12: C4–C5 and 7: C7-T1. Bullet entrance was anterior in 23 patients, posterior in 7 patients and lateral in 10 patients. The cervical vertebrae were injured in 37 patients at body or lamina level while in 3 patients it was only neural tissue injuries. Missiles were retained in 13 patients. All injuries showed some degree of neurological deficit with quadriplegia in 26 patients. 9 patients presented with very serious injuries. No relation was found between the size of the missile and the extent of damage. Outcome of treatment in all patients was poor. Conclusion. Gunshot wounds only account for approximately one third of penetrating missile injuries in patients who survive and are well enough to receive medical treatment. 62% of patients' cohort were from explosive devices, consistent with data from 2010, where 58% of fatalities were from IED's occurring in foreign soldiers in Afghanistan. We discuss the importance of general supportive measures, generous wound excision, removal of the retained missiles and heavy cover of antibiotics

A previously fit and well 58 year old male suffered from a bilateral psoas haematoma (PH) following 52 days of veno-venous extracorporeal membranous oxygenation (VV-ECMO) for severe Coronavirus disease (COVID-19), refractory to all non-invasive and medical therapies. He developed multiple complications, including inability to walk or weight-bear, due to lumbar plexopathy triggered by bilateral PH compression, compounded by COVID-19-related mononeuritis multiplex. The patient was referred to our institution with a known diagnosis of bilateral PH and after spinal multidisciplinary team (MDT) input, was deemed not for surgical or interventional radiology treatments. The patient received extensive neurorehabilitation, coordinated by multiple MDTs. Although PH has been correlated to COVID-19, to the best of our knowledge this is the first reported case of such a complex presentation resulting in a dramatic bilateral PH. Health records from 3 large UK teaching hospitals were collected regarding treatment and follow up appointments, following patient's written informed consent. Patient's comorbidities, duration in hospital units, MDT inputs, health assessments, mobilisation progress and neurologic assessments, were all recorded. Data was collected retrospectively then prospectively due to lengthy in-patient stay. The literature review was conducted via PubMed and open access sources, selecting all the relevant studies and the ECMO guidelines. Patient received treatment from 3 different units in 3 hospitals over 212 days including 103 days in neurorehabilitation. Involvement of physiotherapy, dietitians, speech and language teams, neurologist, neurophysiotherapists, occupational therapists was required. The patient progressed from a bed-bound coma and inability to walk, to standing with lower limb backslab at discharge. Additionally, he was referred for elective exploratory surgery of the psoas region for scar debridement and potential nerve graft repair of the lumbosacral plexus. The surgery outcome is cautiously optimistic, with some improvement in nerve conduction studies, however is currently unknown regarding recovery progress and return to premorbid functional baseline. The novelty of this presentation yields significant learning points regarding early recognition of PH, requirements for vast MDT input and specialist use of VV-ECMO in severe COVID-19 patients. It also highlights the broad pathophysiology of SARS-CoV-2 causing neuropathy and coagulopathy; understanding this will optimise robust anticoagulation guidelines, required in VV-ECMO

Aims. Patient engagement in adaptive health behaviours and interactions with their healthcare ecosystem can be measured using self-reported instruments, such as the Patient Activation Measure (PAM-13) and the Effective Consumer Scale (ECS-17). Few studies have investigated the influence of patient engagement on limitations (patient-reported outcome measures (PROMs)) and patient-reported experience measures (PREMs). First, we assessed whether patient engagement (PAM-13, ECS-17) within two to four weeks of an upper limb fracture was associated with limitations (the Quick Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH), and Patient-Reported Outcome Measurement Information System Upper Extremity Physical Function computer adaptive test (PROMIS UE PF) scores) measured six to nine months after fracture, accounting for demographic, clinical, and psychosocial factors. Secondly, we assessed the association between patient engagement and experience (numerical rating scale for satisfaction with care (NRS-C) and satisfaction with services (NRS-S) six to nine months after fracture. Methods. A total of 744 adults with an isolated fracture of the proximal humerus, elbow, or distal radius completed PROMs. Due to multicollinearity of patient engagement and psychosocial variables, we generated a single variable combining measures of engagement and psychosocial factors using factor analysis. We then performed multivariable analysis with p < 0.10 on bivariate analysis. Results. Patient engagement and psychosocial factors combined to form a single factor (factor 1) accounting for 20% (QuickDASH, semi-partial R. 2. = 0.20) and 14% (PROMIS UE PF, semi-partial R. 2. = 0.14) of the variation in limitations six to nine months after fracture. Factor 1 also accounted for 17% (NRS-C, semi-partial R. 2. = 0.17) of variation in satisfaction with care, and 21% (NRS-S, semi-partial R. 2. = 0.21) of variation in satisfaction with services. Demographic factors (age, sex, work status) and measures of greater pathophysiology (type of fracture, high-energy injury, post-surgical complications), accounted for much less variation. Conclusion. Patients who actively manage their health and demonstrate effective emotional and social functioning share a common underlying trait. They have fewer limitations and greater satisfaction with care during recovery from upper limb fractures. Future efforts should focus on evaluating initiatives that optimize patient engagement, such as patient education, coaching, and a communication strategy for healthcare professionals. Cite this article: Bone Joint J 2020;102-B(1):42–47

While knee osteoarthritis (OA) is now recognized as a complex disease affecting the whole joint, not just the cartilages, there remains a paucity of data regarding the interactions between knee components. One relationship of particular interest is between the spatial variations in cartilage thickness (CTh) and subchondral bone mineral density (BMD). Indeed, bone and cartilage are two mechanosensitive tissues that interact as a functional unit and there is evidence of a biomechanical coupling between both tissues. Particularly, a recent in vivo study has shown a positive relationship in non-OA knees with thicker cartilage where bone is denser, and an alteration of this relationship in OA knees. These observations support the concept of an osteochondral unit and warrant additional research to assess the influence of bone depth. Therefore, this study aimed to characterize the relationship between spatial variations in CTh and BMD measured at various depths below the bone surface. CT-arthrography of 20 non-OA tibias and 20 severe medial-compartment OA tibias were segmented to build 3D mesh models of the bones and cartilages. Each individual tibia model was registered to a reference tibia, allowing to calculate BMD maps at 1, 3, 5 and 10mm below the bone-cartilage interface in the medial compartment. Pearson correlations between CTh maps and the four BMD maps were then calculated for each knee. Lastly, differences in correlation coefficients between successive bone layers were assessed using Wilcoxon signed-rank tests. In both OA and non-OA tibias, the correlation coefficients were higher with the BMD measured in the 1mm layer, and followed a pattern of statistically significant decrease with bone layers of increasing depth (p < 0.021). In non-OA tibias, the median relationship was positive with a strong effect size in the 1, 3 and 5mm layers, while in OA tibias the median relationship was positive only in the 1mm layer and with a medium effect size. In the OA tibias, the median relationship was negative with a weak effect size in the 3 and 5mm layers, and it was negative with a medium effect size in the 10mm layer. In conclusion, the results of the present study support the value of considering bone and cartilage as a unit, and more generally support OA pathophysiology models based on relationships among knee properties

Spinal cord injury (SCI) is a devastating disorder for which the identification of exacerbating factors is urgently needed. Although age, blood pressure and infection are each considered to be prognostic factors in patients with SCI, exacerbating factors that are amenable to treatment remain to be elucidated. Microglial cells, the resident immune cell in the CNS, form the first line of defense after being stimulated by exposure to invading pathogens or tissue injury. Immediately after SCI, activated microglia enhance and propagate the subsequent inflammatory response by expressing cytokines, such as TNF-α, IL-6 and IL-1β. Recently, we demonstrated that the activation of microglia is associated with the neuropathological outcomes of SCI. Although the precise mechanisms of microglial activation remain elusive, several basic research studies have reported that hyperglycemia is involved in the activation of resident monocytic cells, including microglia. Because microglial activation is associated with secondary injury after SCI, we hypothesized that hyperglycemia may also influence the pathophysiology of SCI by altering microglial responses. The mice were anesthetized with pentobarbital (75 mg/kg i.p.) and were subjected to a contusion injury (70 kdyn) at the 10th thoracic level using an Infinite Horizons Impactor (Precision Systems Instrumentation). For flow cytometry, the samples were stained with the antibodiesand analyzed using a FACS Aria II flow cytometer and the FACSDiva software program (BD Biosciences). We retrospectively identified 528 SCI patients admitted to the Department of Orthopaedic Surgery at the Spinal Injuries Center (Fukuoka, Japan) between June 2005 and May 2011. The patients' data were obtained from their charts. We demonstrate that transient hyperglycemia during acute SCI is a detrimental factor that impairs functional improvement in mice and human patients after acute SCI. Under hyperglycemic conditions, both in vivo and in vitro, inflammation was enhanced through promotion of the nuclear translocation of the nuclear factor kB (NF-kB) transcription factor in microglial cells. During acute SCI, hyperglycemic mice exhibited progressive neural damage, with more severe motor deficits than those observed in normoglycemic mice. Consistent with the animal study findings, a Pearson χ2 analysis of data for 528 patients with SCI indicated that hyperglycemia on admission (glucose concentration ≥126 mg/dl) was a significant risk predictor of poor functional outcome. Moreover, a multiple linear regression analysis showed hyperglycemia at admission to be a powerful independent risk factor for a poor motor outcome, even after excluding patients with diabetes mellitus with chronic hyperglycemia (regression coefficient, −1.37; 95% confidence interval, −2.65 to −0.10; P < 0.05). Manipulating blood glucose during acute SCI in hyperglycemic mice rescued the exacerbation of pathophysiology and improved motor functional outcomes. Our findings suggest that hyperglycemia during acute SCI may be a useful prognostic factor with a negative impact on motor function, highlighting the importance of achieving tight glycemic control after central nervous system injury

Periprosthetic joint infection (PJI) is a potentially devastating complication of joint replacement surgery. Osteocytes comprise 90–95% of all cells in hard bone tissue, are long-lived and are becoming increasingly recognised as a critical cell type in the regulation of bone and systemic physiology. The purpose of this study was to examine role of these cells in PJI pathophysiology and aetiology, with the rationale that their involvement could contribute to the difficulty in detecting and clearing PJI. This study examined the ability of human osteocytes to become infected by Staphylococcus aureus and the responses of both the host cell and pathogen in this scenario. Several S. aureus (MRSA) strains were tested for their ability to infect human primary osteocyte-like cells in vitro and human bone samples ex vivo. Bone biopsies were retrieved from patients undergoing revision total hip arthroplasty for either aseptic loosening associated with osteolysis, or for PJI. Retrieved bacterial colony number from cell lysates and colony morphology were determined. Gene expression was measured by microarray/bioinformatics analysis and/or real-time RT-PCR. Exposure to planktonic S. aureus (approx. 100 CFU/cell) resulted in intracellular infection of human osteocyte-like cells. We found no evidence of increased rates of osteocyte cell death in bacteria exposed cultures. Microarray analysis of osteocyte gene expression 24h following exposure revealed more than 1,500 differentially expressed genes (fold-change more than 2, false discovery rate p < 0.01). The gene expression patterns were consistent with a strong innate immune response and altered functionality of the osteocytes. Consistent patterns of host gene expression were observed between experimentally infected osteocyte-like cultures and human bone, and in PJI patient bone samples. Internalised bacteria switched to the quasi-dormant small colony variant (SCV) form over a period of 5d, and the ensuing infection appeared to reach a stable state. S. aureus infection of viable osteocytes was also identified in bone taken from PJI patients. We have demonstrated [1] that human osteocytes can become infected by S. aureus and respond robustly by producing immune mediators. The bony location of the infected osteocyte may render them refractory to clearance by immune cells, and osteocytes may therefore be an immune-privileged cell type. The phenotypic switch of S. aureus to SCV, a form less sensitive to most antibiotics and one associated with intracellular survival, suggests that infection of osteocytes may contribute to a chronic disease state. The osteocyte may therefore serve as a reservoir of bacteria for reinfection, perhaps explaining the high prevalence of infections that only become apparent after long periods of time or recur following surgical/medical treatment. Our findings also provide a biological rationale for the recognised need for aggressive bone debridement in the surgical management of PJI

Tendon disease causes widespread morbidity ranging from mild pain to catastrophic end-stage rupture. The pathophysiology of tendon disease is not certain. An overuse exercise model was developed using rats with the aim of developing tissue with histological, biochemical and biomechanical features similar to those in human tendinosis. Results indicate that the biological response to over-exercise of the rat Achilles tendon is similar to the literature description of pathological specimens of human with disease. Biochemical and histological analysis of the rat Achilles tendons suggest that the patho-physiology is more consistent with a repair response than with a classical inflammatory response. Tendon disease causes widespread morbidity ranging from mild pain to catastrophic end-stage rupture and the pathophysiology of tendon disease is not certain. To develop an overuse exercise animal model to study the pathophysiology of Achilles tendon disease. Experimental rats were subjected to an over-exercise running regime, while control rats were maintained under normal cage activity. Achilles tendons were analyzed for histological features, glycosaminoglycan content, collagen content, collagen subtype, collagen crosslinking (hydrothermal isometric tension testing), and mechanical properties. Experimental rat Achilles tendons demonstrated: increased nuclear numbers per high-power field (527 vs. 392, p < 0.05), decreased semi-quantitative grade for collagen organization (2.9 vs. 3.7, p < 0.05) and decreased semi-quantitative grade for collagen staining (1.9 vs 3.5, p < 0.05). The total collagen content remained unchanged (84.3 vs. 89.0% p=0.38), while the glycosaminoglycan content was increased (17.5 vs. 9.0% p=0.02). Increased levels of collagen type III were not demonstrated, however. Experimental tendons were determined to have distinct differences in the collagen crosslinking patterns, with reduced total cross links and a greater population of immature, hydrolytically unstable cross links. These differences did not, however, translate into a decrease in ultimate tensile failure during mechanical testing (UTS of 77.8 vs. 88.8 N, p=0.26). The histology and biochemistry observed in the experimental rat Achilles tendons were similar to those described in the literature on human Achilles tendon disease. The rat Achilles tendon over-exercise model has demonstrated histopathology that was different from a control group and was consistent with the human literature for Achilles tendon disease. Research Grants were received from the following organizations:. Canadian Orthopaedics Foundation. American Foot and Ankle Society. Dalhousie University Department of Surgery. Nova Scotia Capitol District Health Authority Research Fund

Objectives. Diabetes mellitus (DM) is known to impair fracture healing. Increasing evidence suggests that some microRNA (miRNA) is involved in the pathophysiology of diabetes and its complications. We hypothesized that the functions of miRNA and changes to their patterns of expression may be implicated in the pathogenesis of impaired fracture healing in DM. Methods. Closed transverse fractures were created in the femurs of 116 rats, with half assigned to the DM group and half assigned to the control group. Rats with DM were induced by a single intraperitoneal injection of streptozotocin. At post-fracture days five, seven, 11, 14, 21, and 28, miRNA was extracted from the newly generated tissue at the fracture site. Microarray analysis was performed with miRNA samples from each group on post-fracture days five and 11. For further analysis, real-time polymerase chain reaction (PCR) analysis was performed at each timepoint. Results. Microarray analysis showed that there were 14 miRNAs at day five and 17 miRNAs at day 11, with a greater than twofold change in the DM group compared with the control group. Among these types of miRNA, five were selected based on a comparative and extended literature review. Real-time PCR analysis revealed that five types of miRNA (miR-140-3p, miR-140-5p, miR-181a-1-3p, miR-210-3p, and miR-222-3p) were differentially expressed with changing patterns of expression during fracture healing in diabetic rats compared with controls. Conclusions. Our findings provide information to further understand the pathology of impaired fracture healing in a diabetic rat model. These results may allow the potential development of molecular therapy using miRNA for the treatment of impaired fracture healing in patients with DM. Cite this article: S. Takahara, S. Y. Lee, T. Iwakura, K. Oe, T. Fukui, E. Okumachi, T. Waki, M. Arakura, Y. Sakai, K. Nishida, R. Kuroda, T. Niikura. Altered expression of microRNA during fracture healing in diabetic rats. Bone Joint Res 2018;7:139–147. DOI: 10.1302/2046-3758.72.BJR-2017-0082.R1

Aim. Cutibacterium acnes (CA) is one of the crucial actors in spine instrumentation or shoulder prosthesis. Its population is subdivided into 6 major phylotypes: IA1, IA2, IB, IC, II and III. Recent methods for discriminating subpopulations within CA phylotypes highlight the predominance of SLST types H1 to 6 or K1 to 20 in bone and joint infection (BJI). The impact of their ability to produce a biofilm during the development of the infection (with resistance / tolerance to antibiotics used for treatment) remains little studied. Method. The purpose of this study was to determine whether the ability to establish a biofilm varied according to the different subtypes of clinical strains of CA previously characterized and involved in BJI (hip, knee and shoulder prosthesis). The BioFilm ring test (BioFilm Control®) method with index determination, called BFI (BioFilm Index) inversely proportional to the level of biofilm production was used (BFI = 0.00 indicates a high production of biofilm versus BFI = 20.00 indicates zero production). The BFI was determined after 3 h (T3) and 6 h (T6) incubation. The strains used came from patients, 5 belonging to the IA1 phylotype (SLST A1 and D1 types) and 4 to different phylotypes (IA2, IB, II and III). Results. The results show that the kinetics of establishment of an early CA biofilm turns out to be phylotype dependent. The most productive strains are those belonging to phylotype II (BFI T3 = 5.73, BFI T6 = 0.00) and to type SLST D1 belonging to phylotype IA1 (BFI T3 = 4.07, BFI T6 = 0.00). The other strains did not demonstrate saturated BFI, even after 6 h of incubation. Conclusions. The exact role of CA, as well as its ability to produce a biofilm in the pathophysiology of BJI, remains poorly understood and the prolonged use of antibiotics to treat these infections is necessary, especially if devices have not been removed, with potential risk of increasing antibiotic resistance and therapeutic failures. CA's different phylotypes demonstrate different biofilm production capabilities, which could have an impact on the antibiotic efficacy suggesting the interest of effective anti-biofilm molecules on metabolically less active strains

Human in vitro models of the neuromuscular junction (NMJ) are currently moving from embryonic stem cells to induced Pluripotent Stem Cells (iPSCs). With this, a robust model could be optimised for physiology and pathophysiology studies, as well as representing a drug screening platform. For this reason, the work presented here represents the optimisation of a human co-culture model of skeletal muscle (hSkM)/ iPSC-derived motor neurons (MNs) both in monolayer and in 3D tissue engineering collagen constructs. Firstly, human iPSC-derived motor neurons (MNs) were characterised over a period of 35 days to test their cholinergic potential. Then, primary human skeletal muscle (hSkM) and MNs were co-cultured on different substrates (gelatin and SureBond+ReadySet (Axol Bioscience)) and differentiated in various combinations of media to allow both myotube formation and neurite extension. Morphological (β-III Tubulin and Rhodamine Phalloidin) and interaction (α-Bungarotoxin and Synaptic Vesicle 2) immunofluorescent stainings were used to evaluate cell differentiation and co-localisation of pre and post-synaptic markers. Results from this study showed that the MNs presented a cholinergic phenotype up to 21 days; hSkM and MNs co-existed in culture and differentiated in neuronal Maintenance Medium (MM, Axol Bioscience); the 3D constructs allowed alignment and maturation of the muscle tissue, while providing a matrix for neurite extension and NMJ formation. This model has the potential to become a valid tool for in vitro drug screening while reducing the use of animals in research and providing the scientific community with a platform for personalised medicine

Appropriate in vivo models can be used to understand atrophic non-union pathophysiology. In these models, X-ray assessment is essential and a reliable good quality images are vital in order to detect any hidden callus formation or deficiency. However, the radiographic results are often variable and highly dependent on rotation and positioning from the detector/film. Therefore, standardised A-P and lateral x-ray views are essential for providing a full radiological picture and for reliably assessing the degree of fracture union. We established and evaluated a method for standardised imaging of the lower limb and for reliably obtaining two perpendicular views (e.g. true A-P and true lateral views). The normal position of fibula in murine models is posterolateral to the tibia, therefore, a proper technique must show fibula in both views. In order to obtain the correct position, the knee joint and ankle joints were flexed to 90 degrees and the foot was placed in a perpendicular direction with the x-ray film. To achieve this, a leg holder was made and used to hold the foot and the knee while the body was in the supine position. Lateral views were obtained by putting the foot parallel to the x-ray film. Adult Wister rat cadavers were used and serial x-rays were taken. A-P view in supine position showed the upper part of the fibula clearly, however, there was an unavoidable degree of external rotation in the whole lower limb, and the lower part of the fibula appeared behind the tibia. Therefore, a true A-P view whilst the body was in the supine position was difficult. To overcome this, a P-A view of the leg was performed with the body prone position, this allowed both upper and lower parts of the fibula to appear clearly in both views. This method provides two true perpendicular views (P-A and lateral) and helped to optimise radiological assessment

Complex pathophysiologies involve different signalling mechanisms, with a multitude of often interconnected potential therapeutic targets. Therefore, there is a need for the development of multi-compartment delivery vehicles for combinatorial and synergistic therapeutic approaches. In this study it was hypothesized that multi-compartment crosslinked collagen type I systems can deliver multiple bioactive agents in a controlled manner in an in vitro model condition of skin fibrosis. Multi-compartment collagen-based systems were made using solutions of dialyzed type I collagen mixed with 10× PBS, after which they were neutralised and crosslinked with 1 and 2.0 mM 4 arm-succinimidyl glutarate ester PEG (4 arm-PEG-SG), respectively, followed by incubation at 37ºC. The systems were characterised through swelling assessment, collagenase degradation assay and compression tests. The release of encapsulated drugs from the hydrogels was studied by ELISA and the effect of the delivered bioactive agents was assessed through imaging and quantification for fibrotic markers in an in vitro model. A pilot study using FITC-dextran proved that the inner compartment was capable of promoting a sustained release over a long period of time (7 days), which was further confirmed with drug release assays using a TNF-α antagonist and recombinant decorin, fitting the intended therapeutic release profile. Protein expression studies showed a decrease of endogenous collagen type I and α-smooth muscle actin expression (p<0.05) indicating amelioration of fibrosis. In summary, this indicates that this system is suitable for dual delivery of multiple bioactive agents, resulting in a controlled release in vitro and illustrating its potential in therapy

Dynamic loading is necessary for the preservation of native cartilage, but mechanical disuse is one major risk factor for osteoarthritis (OA). As post-transcriptional regulators, microRNAs (miRs) represent promising molecules to quickly adjust the cellular transcriptome in a stimulus-dependent manner. Several miR clusters were related to skeletal development, joint homeostasis and OA pathophysiology but whether miRs are associated with mechanosensitivity and regulated by mechanotransduction is so far unknown. We aimed to investigate the influence of mechanical loading on miR expression and to identify mechanosensitive miR clusters characteristic for non-beneficial loading regimes which may serve as future tools for improved diagnosis or intervention during OA development. Loading regimes leading to an anabolic or catabolic chondrocyte response were established based on an increase or decrease of proteoglycan synthesis after loading of human engineered cartilage. miR microarray profiling at termination of loading revealed only small changes of miR expression (7 significantly upregulated miRs) by an anabolic loading protocol while catabolic stimulation produced a significant regulation of 80 miRs with a clear separation of control and compressed samples by hierarchical clustering. Overall regulation of 8/14 miR was confirmed by qRT-PCR with mean amplitudes of up to 2.5-fold for catabolic loading. Cross-testing revealed that 2 miRs were upregulated by both loading conditions and 6 were specifically elevated by the catabolic loading regime. Conclusively, this study defines the first mechanosensitive miR cluster associated with non-beneficial compressive cyclic loading of human engineered cartilage which can now be tested for its diagnostic potential in healthy versus OA-affected human cartilage

Synovitis has been shown to play a role in pathophysiology of OA promoting cartilage destruction and pain. Synovium is mainly composed of synovial fibroblast (SF) and macrophage (SM) that guide synovial inflammation. Adipose stromal cells (ASC) promising candidate for cell therapy in OA are able to counteract inflammation. Two different subsets of macrophages have been described showing a pro-inflammatory (M1) and an anti-inflammatory (M2) phenotype. Macrophage markers: CD68, CD80 (M1-like) and CD206 (M2-like) were evaluated in osteoarthritic synovial tissue. GMP-clinical grade ASC were isolated from subcutaneous adipose tissue and M1-macrophages were differentiated from CD14+ obtained from peripheral blood of healthy donors. ASC were co-cultured in direct and indirect contact with activated (GM-CSF+IFNγ)-M1 macrophages for 48h. At the end of this co-culture we analyzed IL1β, TNFα, IL6, MIP1α/CCL3, S100A8, S100A9, IL10, CD163 and CD206 by qRT-PCR or immunoassay. PGE2 blocking experiments were performed. In moderate grade OA synovium we found similar percentages of CD80 and CD206. M1-activated macrophage factors IL1β, TNFα, IL6, MIP1α/CCL3, S100A8 and S100A9 were down-modulated both co-culture conditions. Moreover, ASC induced the typical M2 macrophage markers IL10, CD163 and CD206. Blocking experiments showed that TNFα, IL6, IL10, CD163 and CD206 were significantly modulated by PGE2. We confirmed the involvement of PGE2/COX2 also in CD14+ OA synovial macrophages. In conclusion we demonstrated that ASC are responsible for the switching of activated-M1-like to a M2-like anti-inflammatory phenotype, mainly through PGE2. This suggested a specific role of ASC as important determinants in therapeutic dampening of synovial inflammation in OA

Ligaments and tendons are vital musculoskeletal soft tissues, which are commonly injured due to overuse and trauma. Their distinct functions are well known however their unique structure and biochemical composition and how they change with disease is poorly described. The most commonly injured ligament in the dog and man is the cranial cruciate (CCL) and anterior cruciate ligament (ACL) respectively. Therefore, the structure, function and pathophysiology of disease of this ligament has been most commonly studied in both species. Canine cranial cruciate ligament rupture (CCLR) most commonly occurs following gradual ligament degeneration or disease (CCLD) followed by a non-contact injury or a minor trauma. Several studies have described marked degenerative histological changes in ligament structure prior to and following rupture which consist of loss of the collagen fascicular structure, areas of poor collagen fibril staining, a marked increase in “chondroid” type cells and mineralisation. The ECM protein profile is also altered with increased sulphated glycosaminoglycans content, increased immature collagen cross-links as well as enzymes involved in collagen remodelling. In man, similar findings have been described in the ACL with age and in osteoarthritis (OA). Previously it had been thought that ligament degeneration occurred following OA but these more recent studies suggest that ligament degeneration can lead to joint destabilisation and OA. Being able to determine early degenerative ligament changes in spontaneous clinical cohorts and the mechanisms which cause them are ideal starting points to determine targets for future therapies in the prevention of ligament degradation and rupture. Further identification of ligament cell types in terms of degenerative, responsive and regenerative (stem) types is essential to try and alter ligament cellular and extracellular matrices harnessing their therapeutic potential

Objectives. To evaluate the contribution of leptin, an adipose-derived hormone, to the pathophysiology of osteoarthritis (OA), by determining leptin in both synovial fluid and cartilage specimens from human joints, and by investigating the effect on cartilage of intra-articular injection of leptin in rat. Methods. Leptin levels were measured by enzyme-linked immunosorbent assay (ELISA) in synovial fluids sampled from OA patients undergoing either knee replacement surgery or knee arthroscopy. Besides, histological sections of articular cartilage and osteophytes obtained during surgery for total knee replacement, were graded using the Mankin score, and were immunostained using antibodies to leptin, TGF_ and IGF-1. For experimental studies, various doses of leptin (10, 30, 100 and 300μg) were injected into the rat knee joint. Tibial plateaus were collected and further processed for proteoglycan synthesis by radiolabeled sulfate incorporation, and for expression of leptin, its receptor (Ob-Rb), and growth factors by RT-PCR and immunohistochemistry. Results. Leptin was found in synovial fluids from human OA-affected joints, and concentrations were correlated to Body Mass Index. A marked expression of the protein was seen in OA cartilage and in osteophytes, while few chondrocytes produced leptin in normal cartilage. Furthermore, the pattern and level of leptin expression were related to the grade of cartilage destruction, and paralleled those of growth factors (IGF-1 and TGFb-1). Animal studies showed that leptin strongly stimulated anabolic functions of chondrocytes, and induced the synthesis of IGF-1 and TGFb-1 in cartilage at both mRNA and protein levels. Conclusion. These findings provide a new peripheral function to leptin as a key regulator of chondrocytes metabolism, and indicate that leptin may play an important role in the pathophysiology of OA

Objectives. Legg–Calvé–Perthes’ disease (LCP) is an idiopathic osteonecrosis of the femoral head that is most common in children between four and eight years old. The factors that lead to the onset of LCP are still unclear; however, it is believed that interruption of the blood supply to the developing epiphysis is an important factor in the development of the condition. Methods. Finite element analysis modelling of the blood supply to the juvenile epiphysis was investigated to understand under which circumstances the blood vessels supplying the femoral epiphysis could become obstructed. The identification of these conditions is likely to be important in understanding the biomechanics of LCP. Results. The results support the hypothesis that vascular obstruction to the epiphysis may arise when there is delayed ossification and when articular cartilage has reduced stiffness under compression. Conclusion. The findings support the theory of vascular occlusion as being important in the pathophysiology of Perthes disease. Cite this article: M. Pinheiro, C. A. Dobson, D. Perry, M. J. Fagan. New insights into the biomechanics of Legg-Calvé-Perthes’ disease: The Role of Epiphyseal Skeletal Immaturity in Vascular Obstruction. Bone Joint Res 2018;7:148–156. DOI: 10.1302/2046-3758.72.BJR-2017-0191.R1

Introduction. Degenerative disc disease results from mechanical alteration of the intervertebral disc. Biochemical modifications of the nucleus matrix are also incriminated. Furthermore, genetic predispositions as well as vascular factors have been advocated in the process of disc degeneration. A relationship between sciatica and Propionibacterium acnes has been described. However, it remains unclear if the hypothesis of a subclinical spondylodiscitis might play a role in the pathophysiology of degenerative disc disease. The purpose of this study was to analyze the possible presence of bacteria in lumbar discs of patients with degenerative disc disease. Methods. We prospectively analyzed the presence of bacteria in 83 patients (34 males and 49 females, average age 41 years) treated by lumbar disc replacement at L3-L4, L4-L5 or L5-S1. An intraoperative biopsy and microbiological culture were performed for each disc to determine if intradiscal bacteria were present. Great care was taken to avoid any source of contamination during the conditioning process of the biopsy. Microbiological results were compared to the magnetic resonance stages of disc degeneration according to the Pfirrmann and Modic classifications. Possible sources of previous iatrogenic disc contamination after discography or nucleotomy were analyzed. Results. The magnetic resonance stages were Pfirrmann IV or V, with Modic I signs in 32 and Modic II in 25 cases. A preoperative discography was performed in 49 patients, and 24 had previous nucleotomy. Germs were found in 40 discs, 43 cultures were steriles. The following bacteria were evidenced: Propionibacterium acnes 18, Staphylococcus coagulase negative 16, Staphylococcus aureus 3, Gram negative bacilli 3, Micrococcus 3, Corynebacterium 3, others 5. Ten biopsies presented several different germs. Bacteria were predominantly found in males (p=0.012). The mostly positive level was L4-L5 (p=0.075). Histological examination of 31 discs found inflammatory cells in 33 % of the biopsies with positive bacterial culture, versus 5 % of the sterile biopsies (p=0.038). There was no significant relationship between bacterial evidence and Modic sign. A preoperative discography or previous nucleotomies did not represent significant contamination sources. None of the patients presented clinical signs of infection. Conclusions. The finding of bacteria in 48 % of disc biopsies, presence of inflammatory cells at histological examination, the absence of responsibility of the discography as a factor of contamination, and the absence of clinical post-operative infection, defend the hypothesis of a low-grade spondylodiscitis which might play a role in the pathophysiology of degenerative disc disease. On the other hand, the presence of skin commensal bacteria, of ¼ of polymicrobial biopsies, and the fact that previous nucleotomy doesn't seem to be involved in inoculation, cannot allow to eliminate a contamination of the samples. Further studies are necessary to elucidate the responsability of intradiscal bacteria in degenerative disc disease. This could influence our treatment strategy of back pain, which could be based in the future on antibiotics

In this study, we describe a morphological classification for greater tuberosity fractures of the proximal humerus. We divided these fractures into three types: avulsion, split and depression. We retrospectively reviewed all shoulder radiographs showing isolated greater tuberosity fractures in a Level I trauma centre between July 2007 and July 2012. We identified 199 cases where records and radiographs were reviewed and included 79 men and 120 women with a mean age of 58 years (23 to 96). The morphological classification was applied to the first 139 cases by three reviewers on two occasions using the Kappa statistic and compared with the AO and Neer classifications. The inter- and intra-observer reliability of the morphological classification was 0.73 to 0.77 and 0.69 to 0.86, respectively. This was superior to the Neer (0.31 to 0.35/0.54 to 0.63) and AO (0.30 to 0.32/0.59 to 0.65) classifications. The distribution of avulsion, split and depression type fractures was 39%, 41%, and 20%, respectively. This classification of greater tuberosity fractures is more reliable than the Neer or AO classifications. These distinct fracture morphologies are likely to have implications in terms of pathophysiology and surgical technique. Cite this article: Bone Joint J 2014;96-B:646–51

Aims

CRP is an acute-phase protein that is used as a biomarker to follow severity and progression in infectious and inflammatory diseases. Its pathophysiological mechanisms of action are still poorly defined. CRP in its pentameric form exhibits weak anti-inflammatory activity. The monomeric isoform (mCRP) exerts potent proinflammatory properties in chondrocytes, endothelial cells, and leucocytes. No data exist regarding mCRP effects in human intervertebral disc (IVD) cells. This work aimed to verify the pathophysiological relevance of mCRP in the aetiology and/or progression of IVD degeneration.