Journal of Orthopaedic Research

BackgroundComputational modeling is a tool being deployed for orthopaedic solutions but its use in the hand and wrist remains limited. This work used a model to simulate a clinically relevant provocative scaphoid shift maneuver (SSM) with different levels of scapholunate interosseous ligament (SLIL) injuries to observe the effect on different metrics. MethodsA personalized model simulated the full SSM motion cycle from ulnar deviation with extension to radial deviation with flexion informed by the participants motion obtained from dynamic computed tomography. Models repeated the SSM under different levels of SLIL injury and reported changes in joint kinematics, contact mechanics, and ligament forces. ResultsThe fully injured model increased scaphoid dorsal translation, flexion, and radial deviation compared to the intact condition and caused a subluxation of the scaphoid. Radioscaphoid contact areas were approximately 200% greater in the fully injured model compared with all others and the fully injured model was the only condition where contact force decreased across the motion cycle. Ligament forces in the intact condition were on average 33.0 N and 54.2 N for the volar and dorsal SLIL, respectively. Lastly, the long radiolunate, an extrinsic stabilizer, had forces that increased following SLIL injury. ConclusionsComputational models can successfully recreate clinically observed behaviors of an SSM, including scaphoid subluxation, while providing new insights via quantification of contact mechanics and ligament forces. Contact mechanics metrics may be important for understanding the long-term progression of untreated SLIL injuries to osteoarthritis. Additionally, ligament force metrics may explain the progression of SLIL injuries from volar SLIL to dorsal SLIL and highlight the importance of repairing extrinsic stabilizers of the joint, due to increased force sharing following SLIL injury. This work provides a pathway to future studies investigating the effects of SLIL injury and repair, both acutely and chronically.

Anterior cruciate ligament (ACL) injuries disproportionately affect female adolescent athletes, with hormonal influences implicated in this sex disparity. However, the relationship between pubertal hormonal changes and ACL gene and protein expression remains poorly understood. This study characterized hormone receptor expression and transcriptional profiles in the anteromedial (AM) and posterolateral (PL) bundles of female porcine ACLs before and after puberty. ACL bundles were collected from pre-pubescent (8 weeks) and post-pubescent (>8 months) female Yorkshire cross-breed pigs (n=6/group) and analyzed using gene expression profiling, western blotting, and immunofluorescence. Pre-pubescent ACLs exhibited greater expression of primary matrix genes (COL1A1, COL1A2, ELN, TNMD), suggesting active matrix synthesis, while post-pubescent ACLs showed elevated secondary matrix genes (COL3A1, LUM, COMP), indicating a homeostatic state. Notably, estrogen receptor alpha (ER) gene and protein expression were significantly greater in post-pubescent ACLs, particularly in AM bundles, whereas G-protein coupled estrogen receptor (GPR30) expression was elevated pre-puberty. Both receptors were distributed homogeneously throughout the tissue. Progesterone receptor protein expression was not detected in any samples. Histologically, post-pubescent ACLs demonstrated decreased cellularity and thicker fascicles compared to pre-pubescent tissues. These findings indicate that ACL sensitivity to estrogen varies across development, with increased ER expression post-puberty potentially rendering the ligament more responsive to circulating estrogen. This work provides foundational evidence for age-dependent hormonal responsiveness in the ACL and motivates further investigation into how sex hormones influence ACL injury risk in adolescent females.

Ex vivo models bridge in vitro and in vivo systems by preserving native extracellular matrix architecture and multicellular interactions. In articular joint research, osteochondral-synovial co-cultures are particularly valuable for studying bone-cartilage crosstalk and synovial inflammatory regulation. However, a lack of standardized culture conditions regarding glucose and oxygen, two key regulators of cellular metabolism, limits reproducibility and translational relevance. This study aims to define how glucose and oxygen conditions influence joint tissues maintenance in an ex vivo model. Bovine osteochondral explants and synovium are harvested from the stifle joint and co-cultured using either high glucose DMEM (HG, 4.5 g/L) or low glucose DMEM (LG, 1 g/L) under hyperoxic (21% O2) or physioxic (5% O2) conditions. Cell viability, gene expression, and metabolomic profiles are evaluated across tissues. LG conditions increase cell death in the deep zone of cartilage and in subchondral bone. Gene expression and metabolomic analyses reveal tissue-specific effects of glucose and oxygen. In cartilage and bone, glucose-dependent gene regulation and metabolic changes occur under hyperoxia but are largely absent under physioxia, indicating buffering of glucose responses. Gene-specific sensitivity to glucose and oxygen is observed in bone and synovium; however, glucose-induced metabolic responses persist under physioxia only in synovium. Overall, these findings identify oxygen and glucose as critical modulators of joint tissue physiology and support the use of HG, physioxic culture conditions to improve cell viability and stabilize molecular outcomes in ex vivo joint models. This optimized ex vivo model provides platforms for investigating mechanisms relevant to joint-related diseases. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=147 SRC="FIGDIR/small/704322v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@1393324org.highwire.dtl.DTLVardef@4c9393org.highwire.dtl.DTLVardef@16cc00eorg.highwire.dtl.DTLVardef@b4d9ea_HPS_FORMAT_FIGEXP M_FIG C_FIG This study evaluates the effects of glucose concentration and oxygen tension in an ex vivo joint co-culture system to define optimal culture conditions. High glucose medium and physioxic conditions support tissue viability, preserve homeostasis, and enhance the physiological relevance of the ex vivo model.

ObjectiveDuring osteoarthritis (OA) progression, the synovial membrane undergoes profound structural and compositional remodeling and fibrosis. We sought to elucidate how evolving synovial microenvironmental mechanics during fibrotic remodeling influence cell behavior and drive the progression of synovial pathology. MethodsSkeletally-mature male C57BL/6J mice were subjected to destabilization of the medial meniscus (DMM). To control for surgical confounders, both sham-operated and unoperated mice were included, with evaluation at 4- and 8-weeks. Synovial micromechanics were quantified via atomic force microscopy (AFM). Single-cell RNA sequencing (scRNA-seq), RNA fluorescence in situ hybridization (FISH), and flow cytometry were employed to investigate cellular heterogeneity, spatial organization, and crosstalk within fibrotic and non-fibrotic synovial niches. ResultsProgressive fibrotic remodeling and marked matrix stiffening were observed in DMM-operated synovium but absent in sham- and un-operated controls. While both sham and DMM joints mounted an acute stromal and immune response to surgery, these changes resolved over time in sham conditions but persisted in DMM synovium. During disease progression, distinct functional subsets of synovial fibroblasts and immune cells emerged, with mechanosignalling pathways and distinct immune cell-fibroblast crosstalk robustly activated within DMM-induced fibrotic microenvironments. ConclusionThis study demonstrates the complex cellular dynamics and crosstalk that differentiate the evolution of the pathological synovial response in the fibrotic DMM condition relative to surgical sham controls. Our findings highlight mechanotransduction as a central mechanism driving OA synovial pathogenesis and underscore the utility of the DMM model as a platform to dissect the molecular underpinnings of synovial fibrosis.

Traumatic joint injuries both disrupt chondrocyte metabolism and increase the risk for post-traumatic osteoarthritis. Yet the relationships between trauma, altered metabolism, and cartilage degradation remains unclear. This study compares the metabolic responses of bovine (normal) and osteoarthritic (OA) chondrocytes to physiological and injurious mechanical stimuli under normoxic (20% O2) and hypoxic (5% O2) conditions. Using primary chondrocytes encapsulated in agarose, physiological and injurious mechanical stimulation, targeted metabolomic profiling of central carbon metabolites, and O2 saturation measurements, we find that healthy bovine chondrocytes exhibit robust, time-dependent adaptation to mechanical stimuli, whereas OA chondrocytes display a blunted response, particularly under injury conditions. Injurious mechanical stimuli led to altered O2 consumption and glutamine accumulation, suggesting disrupted respiration and reduced protein synthesis hypothesized to be a result of altered mitochondrial metabolism in OA cells. These findings underscore the role of mechanical cues in chondrocyte metabolism and inform future studies aimed at identifying metabolic targets relevant to post-traumatic osteoarthritis progression.

Intervertebral disc degeneration (IVDD) compromises disc structures and mechanics, yet systematic evaluations of the mechanical responses and their relationship to morphological changes in preclinical models remain limited. This systematic review and meta-analysis synthesized mechanical and morphological alterations following experimental disc injury in in vivo animal models. Searches of MEDLINE, EMBASE and Web of Science databases were conducted in accordance with PRISMA guidelines. Study quality and risk of bias were assessed using modified CAMARADES and SYRCLE tools. Twenty-eight studies were included. Pooled analyses showed significant reductions in stiffness, Youngs modulus, and disc height, and significant increases in range of motion and degeneration grade, indicating both mechanical and structural deterioration. Youngs modulus appeared to be the most sensitive marker of functional degeneration. By contrast, creep and other viscoelastic responses showed non-significant changes. High heterogeneity was evident across studies, reflecting variability in injury models, species, timepoints, and testing methods. Evidence of publication bias was detected in several domains, and moderate methodological quality was noted with overall insufficient blinding and lack of sample size calculations. In vivo animal models of IVDD demonstrate robust and consistent mechanical and morphological degeneration after injury. Youngs modulus is a sensitive mechanical indicator, supporting its use in future preclinical research. Standardization of outcome definitions, methodology, and reporting is essential to improve comparability and enhance translation of preclinical findings to clinical research.

The osteochondral junction is a specialized region ensuring the biomechanical and biological integration of the unmineralized articular cartilage with the subchondral bone through an intermediate layer of mineralized cartilage. This location is of clinical relevance, being the target of osteoarthritis. While aging is considered a risk factor for osteoarthritis, the interplay between microstructural and material changes during aging and predisposing to joint degeneration is not fully clear. This is especially true for mineralized cartilage, which remains understudied despite its critical role in load transfer from unmineralized articular cartilage to bone. We investigate age-related alterations of mineralized cartilage and subchondral bone in rat tibiae of adult and aged animals using a multimodal, high-resolution, correlative analysis. Our approach includes micro-computed tomography to measure microstructural features, second harmonic generation imaging to visualize collagen organization, quantitative backscattered electron imaging to map local mineral content, and nanoindentation to obtain mechanical properties. Mineralized cartilage and subchondral bone exhibited distinct age-related modifications. At the architectural level, the subchondral plate thickened and the trabecular network became coarser, those changes being different from those observed in the metaphysis. At the tissue level, mineralized cartilage was less mineralized than bone but exhibits a greater relative increase of mineral content with age, underlying differences in mineralization. A central observation is that aging led to an abrupt transition in mineral content and mechanical properties across the interface between unmineralized and mineralized cartilage, with a conceivable impact on stress localization. Overall, these changes may alter load transfer and contribute to age-related joint degeneration.

IntroductionTrabecular bone exhibits brittle behaviour governed by microscale deformation and damage processes, yet quantitative characterisation of crack progression remains challenging because classical fracture mechanics approaches do not apply to architecturally discontinuous porous tissues. This study evaluates whether synchrotron X-ray computed tomography (XCT) combined with digital volume correlation (DVC) can provide a practical experimental approach for quantifying crack opening behaviour in human trabecular bone. MethodSemicylindrical specimens harvested from femoral heads of hip-fracture donors (n = 5) and non-fracture controls (n = 5) underwent stepwise three-point-bending during XCT imaging. Full-field displacement maps enabled direct measurement of crack mouth opening displacement (CMOD), crack length (a), and their ratio, CMOD/a, used here as a geometry-normalised comparative descriptor of brittle response. Automated crack segmentation using phase-congruency crack detection (PCCD) was compared against manual measurements. ResultsXCT-DVC successfully resolved three-dimensional displacement discontinuities during crack initiation and propagation in all specimens. Hip-fracture donors exhibited significantly lower critical crack-opening ratios (CMOD/a)* than Controls (0.31 vs 0.47; p = 0.008) and reached mechanical instability at lower applied loads, consistent with a more brittle structural response under this test configuration. Despite these differences, total crack extension ({Delta}a*) was similar between groups. Automated crack tracking using phase-congruency-based segmentation showed excellent agreement with manual measurements (r{superscript 2} = 0.98), confirming reliable extraction of crack geometry from DVC displacement fields. DiscussionThese results indicate that XCT-DVC can provide a practical approach for quantifying crack-opening behaviour in trabecular bone when classical fracture-mechanics parameters are not applicable in anatomically constrained specimens. The reduced critical crack-opening ratios and earlier instability observed in Hip-fracture donors are consistent with a more brittle comparative mechanical response that is not captured by crack extension alone. The strong agreement between automated and manual crack measurements further supports displacement-based descriptors as reliable comparative indicators of brittle behaviour in porous, architecturally discontinuous tissues. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=76 SRC="FIGDIR/small/714043v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@31c5d7org.highwire.dtl.DTLVardef@1b3d9a4org.highwire.dtl.DTLVardef@95df7borg.highwire.dtl.DTLVardef@1834216_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO C_FIG

BackgroundLongitudinal bone growth occurs via the process of endochondral ossification, involving a complex interplay of chondrocyte proliferation, differentiation, and matrix remodelling. As with all mammalian cells, chondrocytes require dynamin for mitochondrial fission, to shuttle vesicles from the Golgi apparatus, and for both clathrin- and caveolin-mediated endocytosis. Here, we aimed to test the functions of dynamin on bone growth. To do so, we applied dynasore - a small molecule that is a reversible dynamin inhibitor - to mouse metatarsal bones cultured ex vivo. We assessed gross changes using bone length measurements and histomorphometry, and combined this with EdU detection, immunostaining, super-resolution microscopy and transmission electron microscopy. ResultsDynasore induced a dose-dependent hormetic effect on bone elongation: while high concentrations (220 {micro}M) impaired growth and abolished chondrocyte proliferation, low-dose treatment (40 {micro}M) significantly increased longitudinal bone growth. Histological analysis demonstrated that low dose dynasore augmented epiphyseal cartilage expansion and matrix accumulation, particularly within the resting and proliferative zones, while reducing chondrocyte proliferation. Immunostaining indicated that 40 {micro}M dynasore preserved collagen type X synthesis, activated mTORC1 signalling, and blocked autophagy, based on SQSTM1 accumulation. Low dose dynasore treatment expanded the thickness of the filamentous actin layer at the plasma membrane and deepened collagen fiber-containing endocytic pits, indicating that impaired cartilage remodelling was associated with growth-associated matrix accumulation. ConclusionsThis study reveals that dynasore exerts hormetic effects on growth plate chondrocytes, wherein low doses stimulate bone elongation, and high doses impair chondrocyte function.

IntroductionSuccessful reinnervation following peripheral nerve injury is highly variable, and the molecular programs underlying human muscle degeneration and recovery remain poorly defined. There is a critical need for high-resolution, spatially resolved gene expression data from human skeletal muscle obtained in clinically relevant settings. This study aimed to establish the feasibility of applying spatial transcriptomics to intra-operatively human muscle biopsies and to generate a framework for identifying gene expression signatures associated with reinnervation outcomes. MethodsTo validate the workflow, we collected biopsies intraoperatively from upper-extremity muscles during standard-of-care orthopaedic surgical procedures 5 months after traumatic brachial plexus injury. The flash-frozen biopsy was processed using the 10x Genomics Visium HD high-resolution platform. Quality metrics confirmed high RNA integrity and robust transcript detection at 8 {micro}m resolution. ResultsGenes involved in neuromuscular junction formation, degeneration, and regeneration were identified at subcellular resolution and showed fiber-type-specific expression patterns. Analyses were performed using complementary approaches in Seurat and Loupe Browser. ConclusionsTogether, these findings demonstrate the feasibility of spatial transcriptomics in human muscle, establish baseline gene-expression signatures, and provide a foundation for future studies aimed at identifying biomarkers associated with successful reinnervation and improved nerve-repair strategies.

Intervertebral disc degeneration is associated with loss of nucleus pulposus (NP) cell phenotype and extracellular matrix, both processes linked to changes in cytoskeletal contractility and cell shape. Here, we tested whether microenvironment-specific modulation of RhoA signaling can restore NP-like morphology and gene expression in NP cells cultured in 2D and in 3D alginate. In 2D monolayer culture, where cells are spread and mechanically activated, pharmacologic inhibition of RhoA with CT04 reduced RhoA activity, decreased actomyosin contractility gene expression, and shifted morphology toward a smaller, more circular phenotype. Bulk RNA sequencing showed that CT04 treatment increased expression of NP phenotypic and matrix-related genes including ACAN, GDF5, CHST3, and MUSTN1 while decreasing expression of catabolic and fibroblast-associated genes including ADAMTS1/9 and COL1, consistent with enrichment of extracellular matrix pathways. In contrast, RhoA activation with CN03 in 2D culture increased actin and phosphorylated myosin light chain intensity but produced limited phenotypic improvement. In 3D alginate, which minimizes integrin-mediated adhesion, baseline actomyosin markers were reduced relative to 2D culture. In alginate, RhoA activation with CN03 increased the amount of actin, phosphorylated myosin light chain, and actomyosin gene expression, yet also promoted a more compact, circular morphology and increased NP markers, including ACAN and KRT19 with repeated dosing. Across culture conditions, increased cell roundness was consistently associated with increased ACAN expression, indicating strong coupling between cytoskeletal state, morphology, and NP matrix programs. Together, these findings demonstrate that RhoA pathway perturbation can promote NP phenotypic gene expression in both 2D and 3D culture, but the direction of optimal modulation depends on the microenvironment, supporting RhoA signaling as a context-dependent therapeutic target for disc regeneration.

ObjectiveTo validate SERPINB2 and SERPINA9 as chondrogenic biomarker candidates across independent transcriptomic platforms and cell sources, to characterise the complete SERPIN expression landscape during kartogenin (KGN)-induced chondrogenic differentiation of human mesenchymal stem cells (hMSCs), and to identify novel SERPIN biomarker candidates and their signalling context during cartilage lineage commitment. DesignMulti-platform transcriptomic analysis across three independent datasets: (i) Affymetrix HGU133+2 microarray of KGN-induced chondrocytes versus undifferentiated hMSCs (ATCC source); (ii) Affymetrix Clariom D whole-transcriptome array of KGN-treated versus control hMSCs from an independent Mexican source (SINREG Laboratories); and (iii) previously published qPCR validation. Differential expression was computed using limma with Benjamini,Hochberg correction. SERPIN-focused cross-platform correlation and targeted pathway analysis were performed. ResultsThe Clariom D dataset yielded 1,869 differentially expressed genes (925 upregulated, 944 downregulated; FDR < 0.05) from 29,124 transcripts tested. SERPINB2 was concordantly upregulated across all three platforms (Clariom D: fold-change [FC] +3.54, FDR = 0.006; HGU133+2: log2FC = +3.29, nominal P = 0.027; qPCR confirmed), establishing it as one of the most reproducible transcriptomic signals in chondrogenic differentiation. In the direct Bone versus Cart comparison, SERPINB2 showed [~]45-fold chondrogenic enrichment (log2FC = -5.45, adjusted P < 0.0001). Cross-platform SERPIN correlation was significant (Pearson r = 0.54, P = 0.0025; n = 29 shared genes). Four additional SERPINs reached genome-wide significance on Clariom D: SERPINE2 (FC +2.57), SERPING1, SERPIND1, and SERPINE1. SERPINA9 was not replicated in the independent SINREG source, identifying it as a context-dependent marker. ConclusionsSERPINB2 is a robust, cross-platform chondrogenic biomarker with translational potential for osteoarthritis (OA) monitoring. The coordinated SERPIN programme activates a multi-layered proteolytic and signalling network during cartilage lineage commitment, positioning SERPINB2 as a functional regulator of the chondro-osteogenic lineage decision.

BackgroundCranioplasty following decompressive craniectomy can be performed using various implant materials, with titanium and polyetheretherketone (PEEK) being the most commonly used synthetic options. However, their comparative safety and clinical performance remain debated. This systematic review and meta-analysis aimed to compare titanium-based cranioplasty with PEEK and other synthetic or autologous materials regarding implant survival, complications, functional outcomes, cosmetic results, and operative metrics. MethodsThis systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines and registered in PROSPERO (CRD). A comprehensive search was performed in PubMed, Embase, Scopus, Web of Science, and the Cochrane Database of Systematic Reviews (CDSR) without language or date restrictions. A total of 1,026 records were identified (Embase n = 263, Web of Science n = 272, Scopus n = 293, PubMed n = 193). After removal of 550 duplicates, 78 articles underwent full-text review, and 38 comparative studies met the eligibility criteria for qualitative synthesis. Three studies directly comparing titanium and PEEK with extractable infection data were included in the meta-analysis. Risk of bias was assessed using Joanna Briggs Institute (JBI) tools. ResultsForty-one studies encompassing heterogeneous patient populations and study designs were included, predominantly retrospective cohort studies. Titanium demonstrated shorter operative times and lower intraoperative blood loss compared with autologous bone and, in most studies, compared with PEEK and PMMA. Implant survival outcomes were heterogeneous: PEEK frequently showed lower exposure rates but higher rates of subgaleal fluid collection. Compared with autologous bone, titanium had higher exposure rates but avoided resorption-related failures. Infection outcomes varied across materials; however, pooled meta-analysis demonstrated a significantly lower odds of postoperative infection with titanium compared with PEEK (random-effects model), with moderate heterogeneity. Functional and neurological outcomes were largely comparable across materials, and cosmetic satisfaction was generally high regardless of implant type. ConclusionsTitanium cranioplasty provides favorable operative efficiency and competitive complication rates compared with alternative materials. While exposure risk may be higher than PEEK, pooled evidence suggests a lower infection risk with titanium. Overall, implant material selection should consider patient-specific risk factors, defect characteristics, and surgeon expertise. Further high-quality prospective studies are warranted to strengthen comparative evidence.

BackgroundOsteoarthritis (OA) is a chronic degenerative joint disease characterized by the progressive deterioration of articular cartilage, significantly impacting the quality of life in middle-aged and elderly populations. The Ras and Hippo signaling pathways play critical roles in regulating cell proliferation, differentiation, and stress responses; however, their interactive mechanisms in OA remain unclear. This study aimed to identify key genes associated with these two pathways using bioinformatic approaches and to elucidate their potential mechanisms in OA. MethodsTranscriptomic data of OA along with Ras signaling pathway-related genes (RSPRGs) and Hippo signaling pathway-related genes (HSPRGs) were obtained from public databases. Differentially expressed genes (DEGs) were identified, and key genes were screened through machine learning, expression validation, and receiver operating characteristic (ROC) curve analysis. Functional insights were further explored via gene set enrichment analysis (GSEA), subcellular localization, immune infiltration analysis, regulatory network construction, and drug prediction. Finally, the expression of key genes was validated in clinical samples. ResultsKIT and CSF1R were identified as key genes. GSEA indicated their involvement in pathways such as the lysosome pathway. Subcellular localization predicted that KIT and CSF1R are distributed in the nucleus, extracellular region, and plasma membrane. Immune infiltration analysis revealed that KIT showed a positive correlation with eosinophils and a negative correlation with immature dendritic cells, while CSF1R was positively correlated with macrophages and negatively correlated with CD56 natural killer cells. Drug prediction suggested interactions between the key genes and several therapeutic agents, including avapritinib and IMC-CS4. Subsequently, we validated our findings in cartilage tissue samples and discovered that compared to the control group, both CSF1R mRNA and protein expression was significantly upregulated in OA tissue, while KIT expression was significantly downregulated.The same results were also validated in immunofluorescence staining of chondrocytes. ConclusionThis study identified KIT and CSF1R as key genes in OA, providing new theoretical insights and potential targets for mechanistic research and targeted therapy.

BackgroundAnterior knee pain (AKP) is common in adolescent athletes and encompasses heterogeneous osseous and soft tissue pathologies, yet its developmental mechanisms remain poorly integrated. HypothesisPain-generating tissues within the knee extensor mechanism are redistributed from osseous to soft tissue structures with skeletal maturation. Study DesignRetrospective observational cohort study. Level of EvidenceLevel 3. MethodsA total of 1,595 patients with sports-related knee injuries (2017-2025) were included. Skeletal maturity was determined by proximal tibial physeal status on radiographs, classifying participants into open-physes (n = 707) and closed-physes (n = 888) groups. AKP was classified into bony and non-bony subtypes based on maximal tenderness. Prevalence was compared using odds ratios (ORs) with 95% confidence intervals (CIs). ResultsOverall, 575 patients (36.1%) had AKP. AKP was more prevalent in the open-physes group than in the closed-physes group (60.1% vs 16.9%; OR, 7.4; 95% CI, 5.9-9.3; p < 0.001). Bony AKP showed a marked difference (42.4% vs 3.7%; OR, 19.1; 95% CI, 12.8-28.6; p < 0.001), whereas non-bony AKP showed only a modest difference (17.7% vs 13.2%; OR, 1.4; 95% CI, 1.1-1.9; p = 0.013). ConclusionThe association between AKP and skeletal maturity was primarily driven by bony AKP, supporting structural redistribution of pain-generating tissues during growth. Clinical RelevanceTenderness-based classification may aid identification of tissue-specific vulnerability and inform growth-stage-specific load management.

ObjectivePhysical activity is a first-line therapeutic intervention for managing osteoarthritis-related pain and functional impairment. However, the growing literature questions the long-term relevance of exercise-induced improvements in patients, while pre-clinical research evidence base is limited by reliance on stressful, forced exercise paradigms which do not reflect voluntary engagement. Here, we aimed to investigate the effects of voluntary wheel running on the pain experience in mice with joint pain. DesignWe investigated the impact of free access to a running wheel on sensory, functional and affective outcomes following unilateral intra-articular injection of monoiodoacetate in single-housed male and female C57Bl/6J mice. ResultsMonoiodoacetate injection transiently reduced running activity in both sexes; however, females rapidly resumed and sustained high activity levels over a two-month period, while males showed a progressive decline in running distance. Active males and females showed improvements in the monoiodoacetate-induced hindpaw secondary mechanical hypersensitivity. Moreover, mechanical thresholds positively correlated with the distance ran after injury, suggesting a functional relationship between exercise and secondary pain relief. However, access to a wheel temporarily exacerbated several monoiodoacetate-induced gait impairments in both sexes. Finally, while there were no obvious effects of running on anxio-depressive-like behaviours or cognitive functioning, exercise significantly impacted stress-induced faecal output and phenotypic regulation of body weight. ConclusionsOur findings suggest that persistent loading of an injured knee joint may compromise functional outcomes independently of pain relief away from the joint, underscoring a critical consideration for exercise-based therapeutic strategies in osteoarthritis.

ObjectiveTo investigate the effects of different gait patterns on knee joint biomechanics and dynamic stability during stair ascent. MethodsFourteen healthy males were recruited to ascend stairs using two distinct gait patterns: the "single-step" (leading with the same leg) and "cross-step" (alternating legs) strategies. Kinematic and kinetic data were collected synchronously using a Qualisys infrared motion capture system and a Kistler 3D force plate. Dynamic stability was quantified using the Margin of Stability (MOS), and knee joint biomechanics were evaluated using Patellofemoral Joint Stress (PFJS) and other relevant metrics. ResultsThroughout the gait cycle, there was no significant difference in the Medio-Lateral (ML) MOS between the single-step and cross-step patterns (P=0.318). However, in the Anterior-Posterior (AP) direction, the MOS for both patterns remained negative and decreased over time, with the cross-step pattern exhibiting significantly lower AP MOS values than the single-step pattern (P=0.002). At the moment of left foot-off, significant differences were observed in the right knee joint angle, right knee joint moment, net joint moment, effective quadriceps muscle lever arm, Quadriceps Force (QF), the angle between the quadriceps tendon and patellar ligament, Patellofemoral Joint Force (PFJF), patellofemoral joint stress, and patellofemoral contact area (all P<0.001). ConclusionsDuring stair ascent, the cross-step pattern reduces body stability, thereby increasing the risk of backward falls. Furthermore, this pattern increases patellofemoral joint stress, subjecting the knee to greater loading. Therefore, it is recommended to enhance lower limb muscle strength through targeted training to reduce fall risk. Additionally, adopting a more cautious gait strategy (such as the single-step pattern) can help minimize patellofemoral joint loading and mitigate the risk of patellofemoral pain.

BackgroundArthroscopic release for elbow stiffness is considered a minimally invasive and effective treatment. However, the extent to which each intraoperative step contributes to improvement in range of motion (ROM) has not been well investigated. PurposeTo sequentially evaluate the relationship between intraoperative surgical steps and changes in elbow ROM during arthroscopic release for severe elbow stiffness, and to identify the key procedural stage contributing most significantly to ROM improvement. MethodsFive elbows in five patients with severe elbow stiffness following fracture or dislocation were retrospectively reviewed. Arthroscopic release was performed using a stepwise posterior-based approach, starting from the posterior soft-spot portal, followed by exposure of the olecranon fossa and progression into the posteromedial compartment. Changes in elbow ROM were assessed at each intraoperative step, and ROM at final follow-up was also evaluated. ResultsAll patients demonstrated improvement in elbow ROM at final follow-up. Intraoperative ROM improvement did not occur in a continuous manner but rather in a stepwise fashion. Gradual improvement was observed with establishment of the posterior and posteromedial working spaces, followed by the most substantial increase in ROM immediately after release of the soft tissue attached to the posterior aspect of the humeral medial epicondyle. Although the maximum ROM achieved intraoperatively was not fully maintained at final follow-up, no patient experienced deterioration to preoperative ROM levels. ConclusionsIn arthroscopic release for severe elbow stiffness, improvement in elbow ROM occurs in a stepwise rather than continuous pattern. Release of the posteromedial structures attached to the posterior aspect of the humeral medial epicondyle may represent a critical turning point contributing significantly to ROM improvement.

BackgroundDexamethasone (DEX) is used in vitro to promote osteogenic differentiation of human bone marrow mesenchymal stromal cells (hBMSCs). In clinical use, however, glucocorticoids induce osteoblast and osteocyte apoptosis while increasing osteoclast survival, leading overall to osteoporosis and high fracture risk. The overall impact of DEX on the differentiation of human progenitor cells remains contradictory and not fully understood, highlighting the need for further investigation using sequencing approaches as in vitro results will naturally influence further translational research. MethodshBMSCs were induced to osteogenic differentiation for 7 days using different concentrations of either DEX or the nonsteroidal glucocorticoid receptor agonist (+)-ZK216348. cDNA library preparation and RNA sequencing (RNAseq) were performed using Oxford Nanopore Technologies. Differentially expressed genes and pathways associated to the transactivation or transrepression activity of DEX were identified. Sequencing results were validated by qPCR, protein analysis, and with a functional assay on peripheral blood mononuclear cells to determine the overall effect of the BMSC supernatant. ResultsHierarchical clustering of RNAseq data identified eight subclusters with shared regulatory patterns. Enrichment analysis revealed that both upregulated and downregulated genes are involved in ossification and extracellular matrix organization pathways. Several pro- and anti-inflammatory genes were differentially regulated. qPCR analysis validated the upregulation of CXCL1, CXCL8, IL18, and COL8A1, while MMP1 and CXCL12 expression decreased in response to DEX. Comparing DEX results with those obtained using (+)-ZK216348 helped distinguish the potential mechanisms regulating the expression of specific genes. Notably, CXCL8 upregulation occurred through transactivation, whereas COL8A1 upregulation is downstream of a transrepressed gene. Further in vitro experiments confirmed that DEX significantly increased CXCL8 expression and IL-8 secretion. However, hPBMC responses indicated no significant pro- or anti-inflammatory effects from hBMSC conditioned medium. ConclusionsIn conclusion, the effects of DEX on the transcriptome of hBMSCs in a pro-osteogenic environment do not fully replicate the acquisition of an osteogenic phenotype. Several genes associated with ossification, extracellular matrix organization, and inflammation were dysregulated. The unique expression patterns of pro-inflammatory cytokines and collagen types warrant further investigation to elucidate their roles in osteogenic differentiation and bone homeostasis.

ObjectivesThis study examined methylglyoxal (MGO) as a collagen crosslinker to reinforce demineralized dentin, enhance its enzymatic resistance, and improve long-term durability of the resin-dentin bond. MethodsDemineralized dentinal collagen films were treated with 0.5, 1, or 3 M MGO and subsequently exposed to collagenase to assess their resistance to enzymatic degradation. MGO-induced crosslink formation was monitored using Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR) spectroscopy by tracking the carbohydrate-associated band at 1180 cm-{superscript 1}. The apparent elastic modulus of the treated specimens was measured using a three-point bending test. For bond strength evaluation, resin-dentin beams were prepared and tested using microtensile bond strength (TBS) to assess the influence of MGO pretreatment on interfacial adhesion. ResultsThe ATR-FTIR spectra demonstrated increased intensity in the carbohydrate double bands (1000-1180 cm-{superscript 1}) in glycated samples compared to the control. Glycation with 3 M MGO exhibited the highest resistance to enzymatic degradation, persisting for up to 60 hours with a 78-fold increase in resistance factor compared to the control group (p < 0.05). Furthermore, glycation with 3 M MGO resulted in a 4-fold increase in elastic modulus compared with the control group. Notably, the functionalized dentin retained its improved mechanical properties even after collagenase exposure, whereas the control group experienced a significant 68.2% reduction in elastic modulus (p = 0.002). While MGO pretreatment did not influence resin infiltration or initial TBS ({approx}30-35 MPa), it maintained its original bond strength after one month of collagenase challenge. In contrast, the control group exhibited a significant reduction, decreasing to 17 {+/-} 5.5 MPa compared with its initial value (p < 0.01). ConclusionMGO demonstrated efficacy in enhancing the mechanical properties and enzymatic stability of collagen as well as improving the resistance of the bonded interface to enzymatic degradation. SignificanceMGO pretreatment maintains the long-term stability of the resin-dentin interface by protecting dentinal collagen from enzymatic degradation, without compromising initial bonding performance. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/701305v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@54ae32org.highwire.dtl.DTLVardef@1787fdforg.highwire.dtl.DTLVardef@130b40org.highwire.dtl.DTLVardef@47c5f9_HPS_FORMAT_FIGEXP M_FIG C_FIG