Journal of Orthopaedic Research

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

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.

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.

Purpose To determine whether clinically significant weight loss (>5% of body weight) is associated with slower 2-year knee cartilage degeneration in individuals with and without radiographic osteoarthritis. This study used a cartilage structural assessment score derived from the spatial distribution of cartilage thickness, referred to as the Cartilage Thickness Score (CTh-Score). It is based on cartilage thickness patterns and scores the cartilage between 0 and 100, with higher scores indicating greater severity. Methods We conducted a retrospective matched cohort study within the Osteoarthritis Initiative. High-resolution cartilage thickness maps (CTh-Maps), along with their corresponding CTh-Score, were extracted from a public repository. Participants with complete radiographic and MRI data at baseline and 24 months were stratified by baseline Kellgren-Lawrence (KL) grade into non-radiographic OA (non-ROA; KL<2) and radiographic OA (ROA; KL>=2). Within strata, cases (>5% 2-year weight loss) were propensity score-matched 1:2 to weight-stable controls on age, sex, height, weight, KL grade, joint space width (JSW), KOOS Pain, baseline CTh-Score, and mean cartilage thickness in the medial and lateral femoral and tibial compartments. The primary outcome was 2-year change (delta) in CTh-Score, where higher values indicate worsening. Secondary outcomes were delta JSW, delta regional mean cartilage thickness, and delta KOOS Pain. Non-parametric tests were used. Results We included 164 cases and 328 controls in non-ROA, and 266 cases and 532 controls in ROA. Median (interquartile range) weight loss was -6.10 kg (-8.90, -4.70) versus +0.30 kg (-1.30, 2.20) in non-ROA and -6.80 kg (-9.10, -5.02) versus +0.40 kg (-1.40, 2.82) in ROA (both p<0.001). Weight loss was associated with significantly smaller 2-year increases in CTh-Score: in non-ROA, median 1.58 (0.61, 6.53) vs 3.14 (0.44, 7.12) (p=0.005); in ROA, median 1.69 (0.97, 6.71) vs 2.90 (0.19, 7.38) (p=0.004). No between-group differences were detected for delta JSW or delta regional mean cartilage thickness in any of the 4 ROIs. A trend toward greater KOOS Pain improvement with weight loss was observed in ROA: 2.75 (-3.35, 13.40) vs 0.00 (-5.60, 8.40) (p=0.06). Conclusions Achieving >5% weight loss over 2 years is associated with approximately 50% lower progression in median cartilage degeneration, as assessed by CTh-Score, in both non-ROA and ROA. No change was observed with conventional structural metrics. These findings support weight management as a structural disease-modifying strategy and highlight CTh-Score as a sensitive endpoint.

Objective To evaluate the Cartilage Thickness Score (CTh-Score) as a quantitative measure of cartilage damage severity by assessing its association with three osteoarthritis (OA) milestones and comparing its performance with conventional morphometric measures (radiographic minimum joint space width (JSW) and regional average cartilage thickness). Methods Data were obtained from the Osteoarthritis Initiative (OAI) and the publicly available OAI CTh-Maps and CTh-Score dataset. Three matched case-control designs were used to represent major OA milestones: (i) incident radiographic OA onset, (ii) combined pain and structural progression, and (iii) knee replacement (KR) in the coming 2 years. Progression subjects were extracted from the FNIH Biomarkers Consortium cohort. Cases and controls were compared at 4 years (T-4Y), 2 years (T-2Y), and 0 years (T0) before the milestone. MRI-based CTh-Score and regional average cartilage thickness, as well as JSW, were analyzed cross-sectionally and longitudinally. Associations with case status were assessed using adjusted logistic regression models, and responsiveness was evaluated using longitudinal change and standardized response means. Results The onset cohort included 307 matched case-control pairs, the progression cohort 164 cases and 369 controls, and the KR cohort 81 cases and 324 controls. Across all three study designs, the CTh-Score significantly differentiated cases from controls at all timepoints. In the onset cohort, the CTh-Score was higher in future cases than controls at T-4Y (16.2 vs 12.6, p=0.007), T-2Y (23.5 vs 16.7, p<0.001), and T0 (39.8 vs 18.6, p<0.001), whereas JSW and regional thickness measures showed limited or later discrimination. Similar findings were observed for progression (43.2 vs 33.0 at T-4Y; p<0.001) and KR (55.4 vs 46.1 at T-4Y; p=0.02) cohorts. Longitudinally, CTh-Score changes differentiated cases from controls earlier and more consistently than JSW or regional average thickness, and its responsiveness was consistently the highest across OA milestones and time intervals. In adjusted models, the CTh-Score was independently associated with all outcomes at T-4Y and T-2Y, with odds ratios per standard deviation increase ranging from 1.3 to 2.2. Conclusion The CTh-Score captures high-resolution cartilage thickness patterns associated with OA onset, progression, and future knee replacement, outperforming conventional morphometric measures in early discrimination, responsiveness, and predictive association. These findings support CTh-Score as a sensitive quantitative marker of cartilage damage severity across the OA continuum.

Objective: This analysis assessed the acceptability and recruitment implications of a high-throughput, community-based biomechanics protocol among individuals with knee osteoarthritis (OA). Design: During the Shared Strides Study, high-throughput markerless biomechanics assessment was conducted at community sites to help facilitate research engagement in the OA population. In this cross-sectional study, biomechanics data during a set of activities of daily living (ADLs) and questionnaire data were collected. Adults aged 40 years or older with knee OA participated at one of four sites across Gainesville, FL--two on-campus and two community-based. Eligible individuals were either screened over the phone and scheduled for a specific date and time or screened on site for potential same-day participation. Participant acceptability of the community-based biomechanics data collection approach was assessed using a 15-item custom questionnaire. Recruitment characteristics and participant preferences were compared across sites. Results: The high-throughput community-based data collection approach was well received. Compared with on-campus sites, community-based sites had higher engagement from walk-in participants and new research participants (40% of the sample). Familiarity with, and distance to, a data collection site were important factors in research engagement in this population. No differences in demographic characteristics existed between sites (p > 0.05), but recruitment resulted in a large sample size (n = 85) likely representative of the communities surrounding the selected sites. Conclusions: Integrating markerless motion capture with a community-based research approach may enhance the participant experience and facilitate larger, more heterogeneous sample sizes, ultimately reducing bias and homogeneity in current OA biomechanics research.

BACKGROUND: Cranioplasty is an essential procedure to restore cranial integrity, protect neural structures, and improve cosmetic outcomes. However, commercially available implants are often costly, limiting their accessibility in public healthcare systems. Three dimensional (3D) printing offers a low cost alternative for producing patient-specific solutions. METHODS: A retrospective case series of eight patients undergoing cranioplasty using customized polymethylmethacrylate (PMMA) implants fabricated with 3D printed molds was conducted. Computed tomography (CT) scans were used for segmentation and digital modeling. Patient specific molds were designed and printed preoperatively. Variables analyzed included design time, printing time, intraoperative workflow, and clinical outcomes. RESULTS: Design time ranged from approximately 1 hour for small defects to 3 hours for larger defects. Printing time ranged from 2 3 hours for smaller defects and up to 8 10 hours for larger reconstructions. Satisfactory aesthetic outcomes were achieved in 7 of 8 patients (87.5%). No major implant related complications were observed. CONCLUSION: Low cost 3D printing for PMMA cranioplasty is a feasible, accessible, and effective technique for cranial reconstruction, particularly in resource limited settings. Keywords: Cranioplasty; 3D printing; Cranial defect reconstruction; Low cost surgery; Patient specific implants; Polymethylmethacrylate; Skull reconstruction

Objectives: Knee osteoarthritis (KOA) is a leading cause of disability, yet which patients will experience structural decline remains unclear. Body mass index (BMI) and lower limb alignment are established risk factors for KOA, but their independent and interactive effects on compartment-specific cartilage loss and total knee replacement (TKR) have not been characterized at scale. Methods: We analyzed 5,832 limbs from 3,016 participants in the Osteoarthritis Initiative followed over 7 years. Cartilage thickness in the weight-bearing medial and lateral femur and tibia was quantified, and lower limb alignment was measured using hip-knee-ankle (HKA) angle obtained from full-limb radiographs. Linear mixed-effects models estimated the independent and interactive effects of BMI and lower limb alignment on longitudinal cartilage thinning, and mixed-effects logistic regression modeled TKR risk. Results: In the medial compartment, BMI and varus alignment interacted multiplicatively, with their combined effect exceeding the sum of independent contributions (femur: p = 0.011; tibia: p < 0.001). At +10 kg/m2 BMI and +10 degrees varus, the rate of medial femur cartilage thinning was 243.5% faster than the reference rate. In the lateral compartment, BMI and valgus alignment were independently associated with faster cartilage thinning, with no significant interaction. TKR risk increased exponentially with HKA deviation (odds ratio [OR] = 1.38 per 1 degree; ~five-fold at 5 degrees malalignment) but was not associated with BMI. Conclusion: BMI and lower limb alignment influence structural KOA progression through compartment-specific pathways. The multiplicative interaction in the medial compartment identifies high BMI combined with varus malalignment as a discrete high-risk phenotype, with implications for clinical risk stratification and disease-modifying intervention design.

Plantar tissue adaptation during activity is thought to contribute to diabetic foot ulceration (DFU), yet most existing studies only measure compressive quasi-static properties. This pilot study developed an ultrasound-loadcell measurement tool, PlantarSense, and used an infrared thermometer to measure dynamic compressive and shear energy dissipation ratio (EDR) and temperature of plantar-tissue at the first metatarsal head (1stMTH) and calcaneus in people living with and without diabetes at baseline, post-walk, and post-recovery. People living with diabetes showed significantly greater post-walk temperature increases (11.0 % vs 6.9% in controls at calcaneus, p=0.03) and less complete thermal recovery than controls. Baseline compressive EDR at the 1stMTH was significantly higher in people living with diabetes (67.8% vs 56.0% in controls, p=0.04). EDR modulation was greater from shear loading (21.5%) than compression (5.4%) and post-walk induced reductions in EDR were present in all participants, but people living with diabetes showed a 20% lower recovery than controls. Impaired thermoregulation and tissue adaptation in people living with diabetes was demonstrated by plantar temperature and EDR differences in post-walk and post-recovery. Future work is needed to test more participants with a greater range of diabetes progression to quantify statistically significant plantar tissue differences to inform DFU risk management.

Objective: To evaluate the feasibility of nurse-led ultrasound hip screening for newborns and infants during home visits, focusing on whether trained public health nurses (PHNs) can obtain interpretable images for orthopedic pediatric surgeons' diagnosis, imaging error patterns, immediate operational challenges, and follow-up results of infants with suspected developmental dysplasia of the hip (DDH). Design: Pilot prospective cohort study. Sample: Forty-two infants were screened. PHNs conducted ultrasound hip screenings during home visits. Measurements: Diagnostically interpretable images, as determined by two pediatric orthopedic surgeons. Results: Diagnostically interpretable images of 75/84 (89.3%) hips were obtained. Surgeons identified three error patterns: incomplete visualization of the ilium (n = 2), joint capsule (n = 1), or bony roof (n = 2). Infant crying was an operational challenge (n = 1). Thirty-three (78.6%) hips were normal, four (9.5%) had abnormal findings requiring abduction exercises, three (7.1%) were referred to a hospital, and two (4.8%) failed imaging. One hip was diagnosed with subluxation, which went undetected by physical or risk screening. Conclusion: Nurse-led ultrasound hip screening for newborns and infants during home visits is feasible and may aid in early DDH detection. Further studies should assess diagnostic accuracy, cost-effectiveness, and long-term outcomes.

Extracellular matrix (ECM) proteins assemble to form a heterogeneous connective scaffold that supports cells. Physical interactions between cells and the matrix regulate cellular behaviors and influence subsequent tissue construction. However, there is a lack of fundamental understanding regarding the contributions of individual native ECM proteins to the matrix. This gap arises from the need for nanoscopic characterization, which operates on a much smaller length scale than typical assessments in cell and tissue cultures, as well as in tissue reconstruction and clinical implantation. This study aims to systematically investigate how individual ECM proteins affect lipid membranes structurally and mechanically, and how these influences regulate cell migration. Results from Langmuir isotherm analysis, X-ray reflectivity measurements, and cell scratch assays demonstrate that strong collagen adsorption on the membrane surface disrupts lipid packing. However, its rigid network provides a sturdy scaffold for cell adhesion, thereby enhancing cell attachment and promoting cell migration. In contrast, elastin has a minimal structural or mechanical impact on the membrane during both adsorption and compression, but it benefits cells by facilitating migration and reducing the risk of infection. Fibronectin, on the other hand, exhibits complex mechanical responses to compression, characterized by significant structural rearrangements that occur during adsorption. This strong interaction with the membrane can result in excessively high adhesion forces, ultimately limiting cell motility. These findings lay the foundation for the design of artificial scaffolds that can manipulate cellular responses, a critical step toward advancing regenerative medicine and tissue engineering. SignificanceFabricating extracellular matrix (ECM) scaffolds from cells offers advantages over traditional approaches, such as decellularized tissues, which face donor limitations, and artificial scaffolds, which may hinder cellular communication. However, the slow harvesting process of cell-derived ECM has limited its clinical applications. This research is part of a larger mission to engineer ECM prescaffolds on lipid carriers tailored to cell requirements, enhancing ECM production and regulating cell behavior. The first step involves systematically analyzing the structural and mechanical effects of ECM on lipid membranes and how these effects regulate cellular behavior. This work confirms distinct characteristics of ECM proteins, advancing fundamental understanding of cell-matrix interactions and paving the way for scaffold engineering.

The bone matrix is precisely maintained and optimized to resist fractures. However, aging and disease deteriorate the bone matrix and increase fragility. Individuals with type 2 diabetes (T2D) have an elevated risk of bone fracture despite apparently normal bone mass. The chronic hyperglycemia in T2D promotes the formation of advanced glycation end-products (AGEs) in the bone tissue and modify the matrix mechanics. AGEs also bind to its receptor, RAGE, to activate inflammation and alter homeostasis. Using a leptin-receptor deficient mouse model of diabetes, we used a combination of high-resolution methods across multiple scales to evaluate the microarchitectural-, material- and cellular- level changes affected by the modulation of RAGE. To demonstrate the relevance of RAGE, we genetically ablated RAGE (RAGE-null) before the onset of diabetes; and to demonstrate the potency of RAGE as a disease modifying therapy, a RAGE antagonist (FPS-ZM1) was administered after prolonged diabetes. Diabetes impaired bone microstructure, the homeostatic actions of bone cells, the bone matrix nanomechanics, and whole- bone strength. The constitutive ablation of RAGE in diabetic animals prevented AGEs accumulation and the decline of trabecular connectivity; protected against the loss of osteocyte lacunae density and morphology; and maintained the matrix nanomechanics and bone strength. The inhibition of RAGE after the onset of diabetes reversed AGE accumulation and loss of bone volume; rescued osteocyte lacunae density and osteoclast activity; and restored matrix nanomechanics and bone strength. These results suggest that RAGE is a viable therapeutic target for diabetes-mediated impairments of bone quality. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=129 SRC="FIGDIR/small/716153v1_ufig1.gif" ALT="Figure 1000"> View larger version (26K): org.highwire.dtl.DTLVardef@6d8a5borg.highwire.dtl.DTLVardef@1967b5borg.highwire.dtl.DTLVardef@7cb1edorg.highwire.dtl.DTLVardef@85491d_HPS_FORMAT_FIGEXP M_FIG C_FIG

Objectives. The association between skeletal muscle gene expression and knee osteoarthritis (OA) was examined among older adult participants of the Study of Muscle, Mobility and Aging (SOMMA). Methods. Inclusion criteria included knee radiographs and bulk RNA sequencing (RNAseq) in vastus lateralis muscle, resulting in 523 participants (56% female). Radiographic knee OA was determined by Kellgren-Lawrence (KL) grades. Differential gene expression was analyzed using a control group (KL [&le;] 1, n = 326) and two nested case groups: (a) KL [&ge;] 2 (n = 197), (b) KL [&ge;] 3 (n = 112). Results. Compared with controls, there were 27 and 41 genes associated (FDR [&le;] 0.05) with KL [&ge;] 2 and KL [&ge;] 3, respectively, and 16 genes significantly associated in both contrasts. For 15 of the 16 genes, the association magnitude was larger with more severe OA (KL [&ge;] 3). Genes associated in both contrasts included brain-derived neurotrophic factor (BDNF) and interferon regulatory factor-2 (IRF2). Gene sets enriched in KL [&ge;] 2 and KL [&ge;] 3 contrasts included DNA repair and branched chain amino acid (BCAA) catabolism. Conclusions. Our results in older adult SOMMA participants indicate that knee OA is associated with genes and pathways expressed in skeletal muscle that are involved in pain sensitization, BCAA catabolism, muscle function preservation, calcium transport and storage, inflammation, and extracellular matrix remodeling. Additional longitudinal studies will be needed to determine how these genes could affect the progression of knee OA.

Background: Peak height velocity (PHV) is a critical indicator of pubertal growth timing and is widely used in orthodontics to determine optimal timing for growth modification interventions. Secular trends toward earlier maturation have been reported, but a quantitative synthesis of PHV age reduction across generations is lacking. Objective: To systematically review and quantitatively synthesize evidence for secular trends in age at PHV and to estimate the pooled mean difference in PHV age between historical and contemporary cohorts. Methods: A systematic search was conducted in PubMed and Google Scholar from January 1990 to December 2021. The Directory of Open Access Journals (DOAJ) was also searched but yielded no eligible studies due to the specificity of the search string. Studies were included if they reported age at PHV in two or more birth cohorts separated by at least 20 years, used objective methods to determine PHV (longitudinal growth data with curve fitting), and reported means with standard deviations or standard errors. Risk of bias was assessed using the Newcastle-Ottawa Scale. A random-effects quantitative synthesis (meta-analytic approach) was performed to calculate the pooled mean difference in PHV age between historical and contemporary cohorts. Between-study variance (tau-squared) was estimated using the restricted maximum likelihood (REML) method. Heterogeneity was assessed using I-squared statistics. Given the limited number of eligible studies, findings should be interpreted as preliminary. Results: Two high-quality longitudinal studies met inclusion criteria, comprising 171 participants from historical cohorts (1969-1973) and 71 participants from contemporary cohorts (1996-2000). The pooled mean difference in PHV age was -0.48 years (95% CI: -0.72 to -0.24, P < 0.001), indicating that contemporary children reach PHV approximately 0.5 years earlier than their historical counterparts. PHV velocity showed a pooled increase of 0.71 cm/year (95% CI: 0.48 to 0.94, P < 0.001). Heterogeneity was low (I-squared = 0% for both analyses). Both studies were rated as low risk of bias. These findings are based on a limited number of studies and should be interpreted as preliminary. Conclusions: This preliminary quantitative synthesis provides evidence of a secular decline in age at peak height velocity of approximately 0.5 years in contemporary children compared to historical cohorts, accompanied by an increase in growth velocity. These findings suggest that orthodontic growth modification strategies may need to be initiated earlier than traditionally recommended. However, given the limited evidence base, results should be interpreted with caution and require confirmation in large-scale longitudinal studies.

BackgroundPhotobiomodulation (PBM) therapy has demonstrated therapeutic potential in promoting cellular repair, modulating inflammation, and enhancing mitochondrial function. Platelet-rich plasma (PRP) is widely used in regenerative medicine due to its concentration of growth factors and cytokines. Very small embryonic-like stem cells (VSELs), a rare population of pluripotent stem cells present in adult tissues, have emerged as a potential contributor to tissue regeneration. While PBM and PRP are used in combination, how VSELs or Multi-lineage stress enduring (MUSE) cells are at play, and the biological mechanisms underlying their synergistic effects remain incompletely characterized. ObjectiveThis exploratory pilot study aimed to evaluate whether application of the MD Biophysics laser to autologous PRP is associated with measurable changes in VSEL-related antibody marker expression, and to identify directional trends to inform future controlled studies. MethodsPRP samples were collected from participants across seven test dates (July 2024 to February 2025), yielding 18 participant-session datasets. Samples were analyzed before (Pre) and after (Post) laser application using flow cytometry conducted at a UCLA Flow Cytometry Laboratory. Four VSEL-associated antibody markers were assessed: CD45-CD34+, CXCR4+, CD133+, and SSEA-4+. Analyses were descriptive and focused on paired differences and directional trends due to the exploratory design and absence of a control group. ResultsThree of four VSEL-associated markers (CXCR4+, CD133+, and SSEA-4+) demonstrated a group-level increase in median paired differences following laser application. Directional increases were observed in 12/18 sessions for CXCR4+, 10/18 for CD133+, and 9/18 for SSEA-4+. CD45-CD34+ showed a near-equal distribution of increases and decreases. Ki-67 positivity indicated the presence of viable, proliferative cells. While no findings reached statistical significance due to limited sample size, consistent directional trends were observed across multiple markers. ConclusionApplication of PBM to autologous PRP was associated with directional increases in multiple VSEL-associated antibody markers, suggesting a potential role for stem cell activation or mobilization in the mechanism of action. Although preliminary and not statistically powered, these findings provide hypothesis-generating evidence supporting further investigation. The observed trends informed iterative protocol refinement and establish a foundation for future controlled, adequately powered studies to evaluate clinical efficacy and underlying biological mechanisms.

Background: A previous meta-analysis by Singh-Ospina et al. (2017) suggested that Gender affirming hormone treatment (GAHT) does not change transgender mens bone mineral density (BMD) at any clinically relevant site; emerging studies and advances in synthesis methods necessitate an updated evaluation. The primary aim was to update the bone measures of Singh-Ospina et al. (2017), with the secondary aim to expand measures to how GAHT affects musculoskeletal health. Methods: A systematic review with meta-analysis was conducted using studies published in English up to 31 July 2024, identified through three electronic databases (PubMed, Embase, SportDiscus), and final cross-referencing in summer 2025. Primary outcomes were longitudinal changes in femoral neck (FN), lumbar spine (LS), and total hip (TH) bone mineral density (BMD). Secondary outcomes included body composition and muscle strength. Standardised effect sizes (Hedges g) were pooled using the inverse heterogeneity (IVhet) model. Results: GAHT (4 years) was not associated with significant longitudinal changes in FN, LS, or TH BMD. In contrast, substantial anabolic effects were observed, including increases in BMI (g = 0.13), body mass (g = 0.18), fat-free mass (g = 0.59), and muscle strength (g = 0.86). Heterogeneity was high for muscle strength, FN and TH BMD, limiting confidence in pooled estimates. Conversely, changes in LS BMD, BMI, body mass and fat-free mass demonstrated low heterogeneity and greater consistency across studies. Conclusion: Masculinising GAHT does not negatively affect clinically relevant BMD sites while reliably increasing lean mass and muscle strength; however, the evidence base remains methodologically weak and highly variable, particularly for FN and TH. The need for continued clinical monitoring of bone health and muscle function, alongside high-quality longitudinal research incorporating advanced imaging modalities such as HR pQCT is emphasised. Strengthening the evidence base will be essential for clarifying long-term skeletal trajectories as transgender men age. PROSPERO registration: CRD42024573102

Study design A retrospective case control study Objective To predict proximal junctional kyphosis (PJK) risk by normalizing individual vertebral bone strength using the ratio of vertebral Hounsfield unit (HU) values around the upper instrumented vertebrae (UIV). Summary of background data PJK poses a significant challenge in treating patients after adult spinal deformity (ASD) surgery. While the vertebral body HU value is associated with PJK risk, the optimal threshold remains unclear, and a relative assessment of HU values within individuals has not been conducted. Methods Data on patients who underwent corrective fusion of the middle to lower thoracic region of the pelvis for ASD were assessed. The 126 patients were categorized into PJK and non-PJK groups. We compared the patients' backgrounds, vertebral body HU, and junctional HU ratio, defined as the HU value of UIV+1 divided by the HU value of UIV (HUUIV+1/HUUIV). The UIV+2/UIV+1 HU ratio was calculated similarly. Results The PJK and non-PJK groups included 30 and 96 patients, respectively. After propensity score matching, 28 patients from each group were analyzed. HU values at UIV+2 and UIV+1 (117.0 {+/-} 46.6 vs 145.1 {+/-} 45.9, p=0.018, and 105.5 {+/-} 36.2 vs 147.3 {+/-} 44.9, p<0.001, respectively) were lower in the PJK group. Junctional HU ratio was significantly lower in the PJK group (0.88 {+/-} 0.18 vs 1.13 {+/-} 0.25, p<0.001), and receiver operating characteristic analysis showed that the junctional HU ratio had the highest discriminative ability (area under the curve 0.812). At the optimal cutoff value (HU ratio of 0.905), the sensitivity and specificity for PJK were 64.3% and 89.3%, respectively. Conclusions A low junctional HU ratio was strongly associated with PJK after ASD surgery. This parameter reflects the bone strength mismatch at the proximal junction and may help improve preoperative risk assessment and UIV selection.