Osteoarthritis and Cartilage

ObjectiveCellular senescence has been shown to underlie many age-related diseases, including osteoarthritis (OA). In addition to age, biological sex is an OA risk factor with females at greater risk of hand and knee OA. We profiled the senescence burden in OA human synovial fibroblasts while accounting for these factors to understand how senescence may contribute to the increased burden of OA in females. MethodsSynovial fibroblasts were isolated from tissue obtained at knee arthroplasty for OA from 10 male and 10 female donors. Single cell multiplexed immunofluorescence imaging was used to profile the senescence burden in samples age-matched to account for the differences in chronological age. Clustering was performed using stability and generalizability scoring. ResultsIndependent of chronological age, OA synovial fibroblasts from female donors showed higher levels of senescence associated proteins p16, p21, p53, phospho-p65, IL-6, and IL-8. Assessment of oxidative stress associated proteins NRF2, SEPP1, NQO1 and TXNIP indicated a lower capacity for female cells to respond to oxidative stress. Clustering analysis revealed male and female enriched clusters. The female-enriched clusters showed higher levels of senescence-associated proteins and an increased oxidative stress response. ConclusionsOA synovial fibroblasts from female donors demonstrated higher levels of senescence associated markers, lower ability to respond to oxidative stress, and increased senescence with increasing age. These findings indicate that female synovial fibroblasts are more likely to show markers of senescence and oxidative stress, suggesting senescence can contribute to the increased incidence of osteoarthritis in women.

BackgroundKnee osteoarthritis (KOA) is a prevalent degenerative joint disease in which synovial inflammation and fibrosis are closely linked to pain, stiffness, and functional limitation. Growing evidence suggests that metabolic dysregulation, particularly in lipid metabolism, is involved in KOA pathogenesis, but the underlying mechanisms remain incompletely defined. MethodsSprague Dawley rats underwent bilateral anterior cruciate ligament transection to establish a KOA model; sham-operated rats served as controls. RNA sequencing of synovial tissues was performed to identify differentially expressed genes (DEGs) and enriched pathways, followed by GO/KEGG and GSEA analyses. In vivo, adeno-associated virus vectors were used to overexpress or knock down PPAR-{gamma} and phosphoenolpyruvate carboxykinase 1 (PCK1) via intra-articular injection. Ex vivo, primary rat fibroblast-like synoviocytes (FLSs) were stimulated with IL-1{beta} and transfected with PPAR-{gamma} or PCK1 siRNA/overexpression plasmids. synovitis and fibrosis were evaluated by HE, Masson, and Sirius Red staining, immunofluorescence, ELISA, RT-qPCR, and Western blotting. ResultsRNA-seq revealed 621 up-regulated and 228 down-regulated genes in KOA synovium versus sham, with DEGs significantly enriched in PPAR signaling, adipocytokine, and AMPK pathways. Metabolism-related genes including Fabp5, Plin1, Adipoq, Lep, and Pck1 were up-regulated. GSEA indicated downregulation of PPAR-{gamma} signaling in KOA synovium. In vivo and ex vivo, PPAR-{gamma} expression was reduced in KOA, whereas PCK1, FABP5, and ADIPOQ were increased. PPAR-{gamma} overexpression alleviated synovial inflammation, collagen I deposition, and fibrosis, and suppressed FABP5, ADIPOQ, and PCK1 expression; PPAR-{gamma} knockdown produced the opposite effects. Functional studies showed that PCK1 overexpression aggravated synovial inflammatory cell infiltration and fibrosis, elevated IL-1{beta}, IL-18, and TGF-{beta}, and decreased TIMP1 levels in serum, synovial tissue, and FLSs supernatants, whereas PCK1 silencing reversed these changes. ConclusionsThe PPAR-{gamma}/PCK1 metabolic axis modulates synovitis and fibrosis in KOA. Downregulation of PPAR-{gamma} and consequent upregulation of PCK1 promote synovitis and fibrotic remodeling. These findings identify the PPAR-{gamma}/PCK1 pathway as a potential therapeutic target for KOA.

Introduction: Osteoarthritis (OA) is a degenerative joint condition characterized by chronic pain and the need for pain management. Locally targeting the endocytotic AP2 complex in nociceptors presents a potential strategy for providing sustained pain relief in individuals with OA. Objective: We investigated whether pain behavior associated with OA can be mitigated by genetically silencing the AP2alpha2 subunit of the AP2 complex in nociceptors and by pharmacologically inhibiting the AP2 complex through the intraarticular administration of a small lipidated decoy peptide. Method: Monoiodoacetate (MIA) was employed to induce knee joint OA in mice and rats. Pain behavior was assessed using dynamic weight-bearing and von Frey filaments. Upon confirmation of established OA pain behavior, in vivo AP2alpha2 genetic knockdown in mice was achieved through sciatic nerve transfection of a targeting AP2alpha2 short hairpin RNA (shRNA). To pharmacologically target endocytosis, a single intraarticular injection of peptide was administered into the arthritic knee of rats. The injection contained either the AP2 inhibitor peptide or a scrambled peptide control. Results: Pain behavior was significantly reduced after both genetic and pharmacological disruption of AP2-driven endocytosis. Animals treated with the Ap2 inhibitor peptide exhibited reduced pain behavior throughout the 28-day assay period. Following the completion of behavioral testing, arthritic knee joints and contralateral healthy knee joints were subsequently collected to assess the impact of the treatment on disease progression. Micro-computed tomography analysis revealed a preservation of bone volume in the arthritic joints that received the AP2 inhibitor peptide treatment, in contrast to the scrambled peptide group. Conclusion: These findings demonstrate that the inhibition of nociceptor endocytosis by a small lipidated peptide presents a promising approach to provide sustained relief from joint pain in individuals with arthritis.

Successful cartilage repair remains one of the most significant challenges in the musculoskeletal field. Microfracture (MFx), a form of marrow stimulation, remains the predominant repair technique, but it exhibits routine failure due to inadequate defect fill and inferior fibrotic tissue formation. Whereas current strategies focus on augmenting MFx with scaffolds and bioactive factors, the potential to target the MFx clot itself and use the capabilities of this dynamic environment to guide MFx repair remains largely unexplored. We verified that MFx contraction and fibrosis hinder repair success in minipigs and become evident as early as one week in multiple animal models. Therefore, our objective was to investigate and direct microenvironmental interactions in the MFx clot to promote volumetric maintenance and reprogram cells from a fibrotic to more chondrogenic phenotype. Extracellular control of cell-environment interactions, through fibrinogen augmentation or anti-fibrinolytic treatment, limited contraction but had no effect on or even exacerbated the fibrotic susceptibility of marrow-derived cells (MDCs). Intracellular control of microenvironmental interactions, through modulation of the Rho-ROCK pathway, drove TGF-{beta}3 activity of MDCs along a "chondro-fibro axis". In particular, treatment with the ROCK inhibitor Fasudil drove TGF-{beta}3-treated cells away from a myofibroblast phenotype and towards chondrogenesis. Short-term Fasudil treatment prevented TGF-{beta}3-driven macroscale clot contraction and enhanced cartilage-specific matrix deposition in vitro. In a pilot rat study, this combination treatment improved GAG deposition and better protected surrounding cartilage. These findings suggest that Rho-ROCK modulates TGF-{beta} signaling along this chondro-fibro axis and its precise control could be the key to promoting precise and volumetric cartilage repair through microenvironmental interactions.

Background and purpose: Patellofemoral pain syndrome (PFPS) is a multifaceted condition where proximal, local, and distal factors may contribute to symptoms and limitations. How these factors collectively contribute to PFPS remains poorly understood. Therefore, this study compared proximal, local, and distal mechanical characteristics between individuals with and without PFPS and investigated their association with pain intensity and functional disability. Methods: Eighty participants were included: 40 individuals with unilateral or bilateral PFPS, 40 healthy controls. Isometric muscle strength of hip, trunk, and ankle was assessed using a handheld dynamometer. Joint alignment (Q-angle, rearfoot angle, pelvic tilt) and muscle flexibility (iliotibial band, hamstrings, quadriceps, gastrocnemius, and soleus) were measured using standard clinical techniques. Pain severity was assessed using a visual analog scale (VAS), and functional disability was evaluated using the Kujala score. Results: Individuals with PFPS showed reduced iliotibial band flexibility, decreased hamstring and soleus length, lower hip abductor strength, and greater anterior and lateral pelvic tilt (all p < 0.02). Multivariate analysis identified reduced iliotibial band flexibility (OR = 7.48) and greater anterior pelvic tilt (OR = 11.75) as independent associates of PFPS. Anterior pelvic tilt predicted pain severity, while anterior trunk muscle strength and Q-angle predicted disability. Discussion: Reduced iliotibial band flexibility and increased anterior pelvic tilt were independently associated with PFPS, while anterior pelvic tilt predicted pain severity and anterior trunk muscle strength and Q-angle predicted functional disability. Clinical assessment and rehabilitation of PFPS should therefore extend beyond the knee to include iliotibial band flexibility, pelvic alignment, and trunk muscle strength.

Background Little evidence is available on the epidemiology of different knee injuries at a whole-of-population level. The objective of this article is to provide accurate estimates of knee injury incidence by harnessing the unique comprehensive, population-wide data of New Zealand's universal no-fault injury insurance provider, the Accident Compensation Corporation (ACC). Methods We obtained insurance claims data from ACC covering all knee injury insurance claims approved between 2015 and 2024. We calculated the number of injuries and the incidence rate per 100 000 population, by injury type, year, sex, ethnicity, and age. Results The total number of injuries increased from 184 710 (4 067 per 100 000 population) in 2015 to 244 155 (4 701 per 100 000) in 2024. The most common injuries were other/unspecified ligament sprains, contusions, and collateral ligament sprains. Ligament and cartilage injuries were more common for males than for females, while contusions were more common for females. Ligament tears and dislocations were more common in younger people (15 to 35 years of age), while cartilage injuries were more common at older ages (40 to 65 years). Discussion and Conclusions The rate of knee injuries observed in this study was higher than previously reported in other settings, probably due to broader coverage of injuries treated in primary and community care settings. A broad range of injuries were common, including those that have received less attention in the epidemiological literature to date. More research is needed on the prevention, burden, and outcomes of different knee injuries, beyond a narrow focus on cruciate ligament injuries.

Cellular senescence contributes to the progression of many age related musculoskeletal diseases. Cellular senescence is a biological state that arises from replicative exhaustion and various cellular stressors, including elevated oxidative stress, mitochondrial dysfunction, mechanical overload, and chronic exposure to pro-inflammatory cytokines and proteases. Although senolytic agents show promise for eliminating senescent cells, their translation has been hindered by the lack of physiologically relevant and scalable in vitro screening methods. In the present study, we developed a standardized, physiologically relevant senescence-induction model and validated a metabolic activity assay as a rapid, scalable method for screening senolytic compounds. We used primary human intervertebral disc cells (IVD) as an example, but the workflow applies to many other cell types. To mimic inflammatory and oxidative stress, we used a combination of TLR-2 activation (Pam2CSK4) and tert-butyl hydroperoxide (tBHP), a potent ROS generator. Senescence induction was validated by quantifying {beta}-galactosidase fluorescence intensity, {beta}-gal enzymatic activity, and the expression of the p16 senescence marker across 3 IVD cell types: nucleus pulposus (NP), inner annulus fibrosus (iAF), and outer annulus fibrosus (oAF) cells. The combined Pam2CSK4 + tBHP exposure generated a robust senescent phenotype across all 3 IVD cell types, with oAF cells exhibiting the strongest increases in {beta}-gal fluorescence, {beta}-gal enzymatic activity, and p16 expression. We then used oAF cells to evaluate if the metabolic activity assay (Alamar Blue) could be used to determine both cytotoxicity of senolytic drugs in non-senescent cells and senolytic activity in a mixed population of senescent and non-senescent cells. We validate the method by comparing metabolic activity results with {beta}-gal enzymatic activity and p16 expression in induced and noninduced cells following exposure to three known senolytics (o-Vanillin, RG-7112, and ABT-199). The metabolic activity assay reliably identified a therapeutic window in which the three senolytics were non-toxic to non-senescent cells while selectively reducing metabolic activity in a mixed population of senescent and non-senescent cells. The reductions in metabolic activity in the mixed population correlated with decreases in SA {beta}-gal enzymatic activity and p16 expression, validating metabolic activity as a sensitive and scalable senolytic readout.

Objectives To analyse the long-term effects of a cruciate ligament (CL) injury on health and socioeconomic outcomes. Methods We used a comprehensive national injury insurance database to identify CL injuries occurring in New Zealand between 2009 and 2022, and employed a doubly robust staggered difference-in-differences research design to identify the effects of these injuries on outcomes up to 10 years after injury. The outcomes of interest were healthcare use (hospitalisations, emergency department visits, medications, knee replacement surgery for osteoarthritis), associated healthcare costs, and labour market outcomes (employment rates, income, and government benefit payments). Results We identified 61 344 CL injuries for inclusion in the analysis. Over 10-year follow-up, a CL injury resulted in increased healthcare use (0.6 more hospitalizations [95%CI 0.4 to 0.7], 1.7 more days spent in hospital [95%CI 1.3 to 2.1], 0.4 more emergency department visits [95%CI 0.3 to 0.6], 2.5 more outpatient visits [95%CI 1.8 to 3.2], and 4.7 more medications dispensed [95%CI -1.8 to 11.2]) and public healthcare costs ($7 537; 95%CI 5 888 to 9 186), reduced income (-$6 060; 95%CI -11 644 to -475), and increased benefit payments ($1 152; 95%CI 542 to 1 761). Conclusion CL injuries have long-term impacts on healthcare use and socioeconomic outcomes. Strategies to reduce the incidence of CL injuries have the potential to realise large health and economic benefits.

Objective To characterize regional subchondral bone metabolism before and after acute mechanical loading in individuals with unilateral knee pain using dynamic [18F]sodium fluoride ([18F]NaF) positron emission tomography (PET)/magnetic resonance imaging (MRI), and to investigate relationships with cartilage composition and pain severity. Design Twenty-two individuals with unilateral knee pain and 22 age- and sex-matched healthy controls underwent bilateral dynamic [18F]NaF PET/MRI before and after a standardized stair-climbing protocol in this prospective feasibility study. Automated MRI-based segmentations were used to quantify regional PET standardized uptake values (SUVmean, SUVmax) and pharmacokinetic parameters (K1: bone perfusion, Ki: bone mineralization, extraction fraction) across subchondral bone regions. Quantitative cartilage T2 mapping was performed using qDESS MRI. Painful knees were compared with contralateral asymptomatic knees and healthy control knees using regional effect sizes and regression analyses. Exploratory analyses evaluated associations between PET metrics, cartilage T2, and pain severity. Results Painful knees demonstrated consistently higher baseline subchondral bone metabolic activity than healthy controls, with the largest differences in the medial tibial and medial femoral subchondral bone (Cohen's d=0.51-0.90). Following mechanical loading, exercise-induced increases in bone metabolism were more widespread and demonstrated predominantly moderate-to-large effect sizes (d=0.62-1.15), particularly within the medial and lateral femoral and medial tibial subchondral bone. In contrast, comparisons between painful and contralateral knees showed only localized metabolic differences with predominantly negligible-to-small effect sizes (d=0.16-0.55). Sensitivity analyses adjusting for age and BMI produced similar regional patterns. Exploratory analyses demonstrated generally weak associations between PET-derived metabolic measures, cartilage T2, and pain severity, with only isolated moderate regional correlations. Conclusions Dynamic [18F]NaF PET/MRI demonstrates increased baseline subchondral bone metabolic activity and an exaggerated metabolic response to mechanical loading in symptomatic knees compared with healthy controls. The modest differences between painful and contralateral knees suggest that the asymptomatic limb may not represent a truly unaffected reference. Dynamic [18F]NaF PET provides complementary information beyond cartilage MRI and patient-reported pain and shows promise for investigating subchondral bone metabolism in knee pain, early joint degeneration, and treatment response.

Osteoarthritis is characterized by inflammation, chondrocyte dysfunction, and progressive cartilage degradation. Boric acid (BA), a physiologically relevant boron compound, has shown anti-inflammatory properties, but its effects on human articular chondrocytes remain unclear. This study investigated whether BA could protect primary human chondrocytes against lipopolysaccharide-induced inflammatory injury. Cell survival, membrane damage, apoptosis, inflammatory mediator production, and expression of genes related to inflammation and extracellular matrix degradation were assessed. BA improved chondrocyte survival and reduced membrane damage and apoptosis following inflammatory stimulation. It also suppressed inflammatory and matrix-degrading gene expression, nitrite production, and the release of proinflammatory mediators. These protective effects were generally more pronounced with the higher treatment dose. Analysis of publicly available human chondrocyte RNA-sequencing datasets provided complementary support for the relevance of several investigated inflammatory and catabolic targets. Overall, these findings demonstrate that BA protects primary human chondrocytes against inflammatory and catabolic injury and support its further investigation as a potential chondroprotective approach in osteoarthritis.

Purpose: The primary objective of the Stanford Knee Osteoarthritis PET/MRI Evaluation (SKOPE) study is to develop and evaluate a multimodal, dynamic [18F]NaF PET-MRI framework for characterizing whole-joint physiology and its relationship to osteoarthritis (OA) risk, pain, and disease progression. Specifically, we aim to integrate dynamic PET with quantitative and anatomical MRI, to characterize structural, compositional, and metabolic features across the knee and surrounding musculoskeletal system, evaluate acute tissue responses to exercise, and identify imaging biomarkers associated with OA risk, pain, and disease progression. Methods: The SKOPE study includes multimodal PET-MRI of the knee and surrounding musculoskeletal tissues, with imaging of the knee, tibia, ankle, thigh, hip, pelvis, and lumbosacral spine. Dynamic [18F]NaF PET is combined with conventional anatomical MRI and quantitative MRI techniques, including quantitative double-echo steady-state (qDESS) T2 mapping of cartilage, Dixon fat-fraction imaging, ultrashort echo time (UTE) T2* mapping of short-T2 tissues, UTE imaging of tibial bone, and zero echo time (ZTE) imaging for bone morphology and pseudo-CT generation. Additional MRI sequences characterize muscle composition, bone and joint anatomy, intervertebral discs, and regional vascular anatomy. Selected scans are acquired before and after a standardized exercise protocol to assess the acute physiological response of the joint. Automated segmentation is used to generate subject-specific masks of muscles, bones, vertebrae, and intervertebral discs. A subset of the MRI protocol is repeated at 1- and 2-year follow-up to assess longitudinal changes. Expected Impact: By combining dynamic bone metabolic imaging with quantitative measures of cartilage, menisci, muscle, bone, fat, vascular structures, and the spine and hip, the SKOPE protocol provides a whole-joint and multijoint framework for studying the structural, metabolic, and physiological processes associated with OA and pain. Exercise and longitudinal imaging further enable assessment of acute tissue responses and changes over time, supporting the development of quantitative imaging biomarkers for OA risk, pain, and disease progression.

Osteochondral repair requires restoration of zonally organised articular cartilage and subchondral bone, yet translatable implants rarely reproduce this spatial complexity. Here, we developed an off-the-shelf, cell-free multilayer scaffold comprising a superficial 2% (w/v) articular cartilage extracellular matrix (AC-ECM) phase, an intermediate 5% AC-ECM phase and a basal 6% bone ECM (BN-ECM) phase. The scaffold formed continuous interfaces, displayed regionally distinct pore sizes and resisted permanent deformation during cyclic compression. In vitro, constructs seeded with caprine mesenchymal stromal and articular cartilage progenitor cells supported cell expansion and the accumulation of sulfated glycosaminoglycan- and collagen-rich matrix, with regional differences in collagen I, II and X deposition. Following eight weeks of subcutaneous implantation, cell-seeded scaffolds contained more collagenous matrix than unseeded controls, while vascularisation preferentially localised to the BN-ECM phase. The scaffold was then evaluated against empty defects in a caprine osteochondral model for six months. Scaffold treatment significantly improved macroscopic and histological repair, increased chondral tissue fill (~60% versus ~40%), limited cartilage-like tissue extension into the subchondral region and generated a more native-like superficial collagen organisation. Repair tissue further exhibited greater collagen II immunoreactivity, increased ACAN and COL2A1 expression and reduced COL1A2 expression relative to empty defects, although deeper bone repair was not significantly improved. These findings demonstrate that tissue-specific ECM layering can spatially guide endogenous repair and substantially improve cartilage restoration without exogenous cells or growth factors in a clinically relevant large-animal model, while identifying subchondral bone regeneration as the remaining design challenge for complete osteochondral repair.

Conventional transfemoral amputation disrupts native neuromuscular pathways, limiting prosthetic joint control, sensory feedback, and the perception of the prosthesis as part of the body. To ameliorate these pathologies, we restored the agonist-antagonist relationship of residual muscles in two individuals with above-knee amputation through an interventional surgical revision. Participants trained with a bionic knee prosthesis before and after the surgical revision while generating neuromuscular, cortical, functional, and affective data. Both individuals demonstrated improvements after the revision that could not readily be attributed to training effects, including: 1) increased proprioceptive afferents and stronger activation in cortical regions associated with sensorimotor integration of their missing joints, 2) improved control of the bionic knee during functional tasks including sit-to-stand and stair ascent, and 3) generally greater prosthesis embodiment, proprioception, and phantom limb definition as assessed through questionnaires and interviews. In contrast, training outcomes were more participant-specific and more variably correlated with amount of exposure, especially before the revision. These pilot findings suggest that revisional augmentation of residual neuromuscular tissues to restore agonist-antagonist dynamics may promote sensorimotor coherence and enhance both functional and perceptual integration with a bionic prosthesis, and remaining participant-specific heterogeneities may be attributable to inter-individual difference in residual limbs neuromuscular system, amputation history, and personal beliefs about prosthesis usage.

Chondrosarcoma is a hyper-vascularised, chemoresistant cartilage malignancy driven by VEGF-centred angiogenesis, and local adipose depots are increasingly recognised as paracrine drivers of tumour angiogenesis via adipokines and extracellular vesicles (EVs). The infrapatellar fat pad (IFP), an inflammatory adipose depot within the articular joint in direct cartilage contact, is a key local source of adipose-derived EVs, and thus a candidate driver of angiogenesis in chondrosarcoma. The aim of this study was to determine whether the IFP is a productive source of EVs, and whether IFP-derived EVs induce angiogenesis in articular chondrocytes. The IFP released significantly more EVs than subcutaneous fat (n = 8 per depot; p = 0.027). Treating primary human articular chondrocytes with IFP EVs for 24 h upregulated VEGFA (+1.6-fold, p = 0.036) and downregulated BMP4 (-2.4-fold, p = 0.011), engaging the VEGF/eNOS/ERK axis that drives chondrosarcoma angiogenesis. Re-analysis of a previously published phospho-kinase dataset from the same donor EVs, corroborated by a pooled donor-group analysis (n = 3), supported activation of eNOS, ERK1/2, PLC-{gamma}1 and HSP27. These findings identify the IFP as a dominant source of EVs within the articular joint, which can induce a pro-angiogenic, VEGF-axis switch in articular cartilage cells, supporting a signalling model relevant to chondrosarcoma angiogenesis.

Rationale: Dislocation is the leading reason for early revision surgery. To address the problem of dislocation, the dual-mobility (DM) cup was developed in France in the 1970s. This cup should provide more stability and biomechanically reduce the risk of dislocation. In the Netherlands, most DM cups are placed in specific patients, e.g. with cognitive impairment and for revisions due to recurrent dislocations. Despite the increased and, in some countries, broad use of DM cups, high quality evidence of their (cost)effectiveness is lacking. This study aims to perform a trial to fill this gap in knowledge. Much of the information needed to judge the effectiveness of DM cups is already incorporated in the Dutch Arthroplasty Register (LROI). This register lends itself perfectly for a nested RCT towards this aim. Objective: The primary objective is to investigate whether there is a difference in the number of hip dislocations following primary total hip arthroplasty (THA), using the posterolateral approach, with a DM cup compared to a unipolar cup in elderly patients 1 year after surgery. The secondary objectives are: to investigate whether there is a difference in the number of revisions; to investigate what the cost-effectiveness and cost-utility is of a DM cup compared to a unipolar cup at 1 year follow-up; to investigate whether there is a difference in the number of hip dislocations and revisions between a DM cup and a unipolar cup 2 years after surgery; to investigate whether there is a difference in patient reported outcomes between a DM cup compared to a unipolar cup 1 and 2 years after surgery; to compare the number of hip dislocations, revisions and PROM data between patients in the randomized DM group and patients in an observational cohort DM group. Finally, long-term survival of DM and unipolar cups will be evaluated based on revision and mortality data registered in the LROI. Study design: Prospective multi-center international wide within the European Union (EU), single blinded RCT, nested in the national registry. Study population: Patients [&ge;] 70 years old, undergoing an elective primary THA. Intervention (if applicable): The intervention group receives a THA with a dual mobility cup, the control group receives a THA with a unipolar cup. Main study parameters/endpoints: Primary: The number of dislocations. Secondary: costs, patient reported outcomes and implant survival.

Background: Pain relief is the principal patient-centered goal of surgery for symptomatic lumbar synovial facet cysts, yet comparative reviews have often emphasized cyst recurrence. Whether adding fusion improves postoperative pain or reduces later surgery remains uncertain. Objective: To compare decompression alone with decompression plus fusion, with postoperative back- and leg-pain outcomes as the primary domain. Methods: PubMed, Embase, Scopus, Web of Science, and the Cochrane Library were searched from inception to 2 June 2026. Comparative cohorts and case series with at least five patients were eligible. Twenty-two studies were re-extracted for VAS/NRS scores, change scores, and persistent or recurrent pain. Random-effects restricted maximum likelihood models with Hartung-Knapp inference were used; clinically distinct pain outcomes were analyzed separately. Results: Twenty-two studies (16 cohorts, 6 case series; 51,899 participants) were included. Two studies provided compatible final VAS data. Fusion did not improve postoperative back pain (MD -0.04, 95% CI -0.17 to 0.10; I2=0%) or leg pain (MD -0.03, 95% CI -0.28 to 0.21; I2=0%). Postoperative back pain (RR 0.58, 95% CI 0.14-2.30) and leg/radicular symptoms (RR 0.75, 95% CI 0.42-1.32) were also not significantly reduced. Fusion decreased confirmed cyst recurrence (RR 0.29, 95% CI 0.15-0.57) but not reoperation or subsequent lumbar surgery (RR 0.80, 95% CI 0.42-1.50). Conclusion: Current comparative evidence does not demonstrate superior postoperative pain control with routine fusion. Fusion reduces cyst recurrence without clearly reducing reoperation, supporting selective use when instability is present or anticipated.

Tear fluid is amenable to non-invasive and repeated collection, making it a practical specimen for evaluating exercise-related physiological responses. However, the immediate proteome-wide alterations in tear fluid following acute exercise have not been characterised. In this study, we performed quantitative proteomic profiling of paired tear samples from healthy female participants before and immediately after a single exercise session using data-independent acquisition liquid chromatography-tandem mass spectrometry (DIA-LC-MS/MS). Among the 3,173 identified proteins, 744 were significantly altered post-exercise, of which 484 were up-regulated and 260 down-regulated. Functional enrichment analysis revealed that up-regulated proteins were predominantly associated with translation and ribosome biogenesis, whereas down-regulated proteins were involved in glycan metabolism, lysosomal processing, and extracellular matrix organisation. Collectively, these findings indicate that acute exercise elicits a rapid and coordinated reconfiguration of the tear proteome. This investigation provides a molecular basis for understanding exercise-mediated modulation of tear composition and ocular surface homeostasis.

Background: In Denmark, perioperative high-dose glucocorticoid treatment were step-wisely implemented for total hip arthroplasty (THA), total knee arthroplasty (TKA), and unicompartmental knee arthroplasty (UKA). We aimed to estimate the effect of a single high dose of glucocorticoids on opioid consumption following primary THA, TKA, and UKA. Methods: This was a prespecified analysis of a multicenter natural experiment using electronic health record data. We included elective THA, TKA, or UKA surgeries performed in Eastern Denmark from 2017-2025. At each center, surgeries before implementation of high-dose glucocorticoids served as controls, whereas surgeries after implementation comprised the intervention group. The primary outcome was the between-group difference in cumulative 0-24h opioid consumption, which included preemptive end-of-surgery doses. The predefined minimal important difference was set at 5 mg IV morphine equivalents. Secondary outcomes were maximum 0-10 numerical rating scale (NRS) pain score and incidence of opioid-related adverse events within 24 hours, hospital length of stay, and days alive and out of hospital at 30 days. Results: A total of 47,317 surgeries performed at nine centers were analyzed: 13,010 controls and 34,307 in the intervention group. During the study period, five centers implemented high-dose glucocorticoids for THA patients, two for TKA/UKA patients. High-dose glucocorticoids were administered to 6% of patients before implementation versus 92% after. High-dose glucocorticoids resulted in a mean reduction of 3.8 mg intravenous (IV) morphine equivalents (95% CI 3.3;4.3). The intervention also reduced the maximum 0-24h NRS pain score by 0.8 points (99% CI 0.7;0.9), but there was no difference in adverse events, length of stay, or days alive and out of hospital. Conclusions: Implementation of high-dose glucocorticoids reduced 0-24-hour opioid consumption by 3.8 mg IV morphine equivalents after elective hip and knee arthroplasty. This difference was below the prespecified minimal important difference threshold. Online registration: https://doi.org/10.1101/2025.11.11.25339982

The foreign body response (FBR) is an immune mediated event that occurs with every material implant. The extent of the fibrosis is dependent on many factors including the biomaterial design, tissue location, and host factors such as age, sex, ancestry, diet. There are known clinical outcomes of implants dependent on age and sex, including increased fibrosis and implant failure in aged and female patients. As the population ages, there is a growing need to understand how aging affects the FBR, and how preclinical models can capture this to guide biomaterial design. Here, we investigated how chronic fibrosis in a murine model of the FBR is altered by two biological factors: age and sex. We investigated changes in fibrosis using a volumetric muscle loss (VML) injury model coupled with polycaprolactone (PCL) or polyethylene (PE) microparticle implants. Fibrosis was quantified through gene expression, microscopic analysis of histologic sections, and the corresponding immune response measured via gene expression and flow cytometry data. We found gene expression differences with immune pathways enriched in female mice, and microscopy revealed collagen birefringence area increased in young male mice. Both the innate and adaptive immune response were altered by age and sex via T cell and macrophage phenotype, and the effects of aging differed between sexes. These results reveal both variables contribute to discrepant outcomes in both fibrosis and the local immune response to synthetic material implants. This demonstrates a clear need to understand and account for the influence of biological factors in biomaterial design.

Background Chronic postsurgical pain (CPSP) affects between 7-23% and 13-44% of patients after hip and knee arthroplasty, respectively. Standardised methods of pain assessment provide superior evaluation of pain, including the Oxford Joint Score Pain Subscale (OJS-PS). We aim to estimate the proportion of patients with a phenotype consistent with CPSP through a k-medoids clustering technique and identify a threshold on the OJS-PS to highlight such patients at a population level. Methods In this cross-sectional study Patient Reported Outcomes Measures data 6-months after hip and knee arthroplasty from 2017 to 2025 were examined. An adapted k-medoid clustering technique utilising subsampling, batch assignment and probabilistic consensus allocated clusters. A receiver operator characteristic analysis identified a threshold on the OJS-PS noting the lowest scoring cluster. Our categorisation was compared to self-reported severe or moderate pain; sensitivity, specificity and accuracy of this categorisation were calculated. Results We analysed 109,542 hip and 113,799 knee arthroplasty patients; three clusters were used in each analysis. After hip arthroplasty: 14.4% of patients were assigned to the cluster with the lowest median OJS-PS of 11 [IQR 8 - 13]. A threshold of 15.5 classified patients as severe or moderate pain with 60.6% sensitivity, 91.0% specificity and 85.7% accuracy. Similarly, after knee arthroplasty, 25.3% were assigned to the cluster with the lowest median OJS-PS of 14 [IQR 11 - 16]. A threshold of 18.5 on the OJS-PS had an 85.4% sensitivity, 88.4% specificity and 87.8% accuracy for classifying patients with self-reported severe or moderate pain. Conclusions This robust and scalable clustering technique on ordinal clinical data estimates the proportion of patients reporting a phenotype consistent with CPSP. On a population level the thresholds identified on the OJS-PS could aid screening for potential CPSP patients 6 months after hip and knee arthroplasties.