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Background: Tendon injuries pose significant clinical challenges because of poor vascularity and complex biomechanics, often leading to suboptimal healing. While surgical advancements and rehabilitation protocols have improved outcomes, delayed healing and high retear rates remain prevalent. Vitamin D, a key regulator of musculoskeletal health, may influence tendon healing through extracellular matrix remodeling, inflammation modulation, and cell proliferation. However, its effect on tendon repair remains unclear, with most studies focusing on rotator cuff tendons. This scoping review synthesizes current evidence on vitamin D’s role in tendon healing and identifies gaps in the literature. Purpose/Hypothesis: The purpose of this scoping review is to evaluate the available literature on vitamin D’s role in tendon healing and its influence on postoperative recovery. It was hypothesized that vitamin D deficiency is associated with poorer healing outcomes and increased failure rates. Study Design: Scoping review; Level of evidence, 4. Methods: A systematic search of Embase, OVID Medline, and Emcare databases was conducted through November 2024. Eligible studies included observational studies and randomized controlled trials assessing vitamin D status in adults undergoing tendon repair. Two independent reviewers screened and extracted data, resolving discrepancies with a third reviewer. Study quality was evaluated using the methodological index for non-randomized studies score. Given the heterogeneity of studies, results were synthesized narratively, focusing on evidence gaps across different tendons. Results: A total of 10 studies met inclusion criteria, with the majority focusing on rotator cuff repairs (n = 8). Vitamin D deficiency was consistently associated with poorer postoperative outcomes, including delayed healing, higher retear rates, and decreased functional recovery. Mechanistic studies suggested that vitamin D enhances healing through extracellular matrix remodeling and inflammation modulation. However, the overall quality of evidence was low, with most studies being retrospective. Notably, half of the studies relied on the same large administrative database, leading to potential patient overlap and limiting independent conclusions. Research on vitamin D’s role in healing other tendons, such as the Achilles, patellar, and flexor tendons, was lacking. Conclusion: Although evidence suggests vitamin D may support tendon healing, particularly in rotator cuff repair, studies remain low quality and limited to a single tendon group. Future prospective cohort studies and randomized controlled trials are needed to establish causality, assess its effects across various tendons, and determine optimal supplementation strategies.

Background: The meniscus plays a critical role in knee stability and load distribution, with meniscal tears often resulting from trauma or degeneration. Rehabilitation protocols after meniscal repair lack standardization, particularly regarding weightbearing restrictions and their effect on outcomes. Hypothesis/Purpose: This systematic review hypothesizes that accelerated weightbearing protocols after isolated meniscal repair would lead to improved patient-reported outcomes and comparable failure rates relative to restricted rehabilitation protocols. The purpose was to evaluate the influence of different postoperative rehabilitation strategies on failure rates and functional outcomes after isolated meniscal repair. Study Design: Systematic review; Level of evidence, 4. Methods: Comprehensive searches of Embase, OVID Medline, and Emcare databases were conducted through November 2024. Studies were included if they reported on adult patients undergoing arthroscopic repair for isolated meniscal tears, described postoperative rehabilitation protocols, and had ≥10 months of follow-up. The primary outcome was repair failure (retears, revision surgery, or persistent symptoms). Secondary outcomes included patient-reported outcome measures (PROMs) and postoperative complications. Descriptive statistics summarized findings, with discrepancies resolved by a third investigator. Results: Ten studies (n = 313 patients) met the inclusion criteria. Most tears were medial (62%-93%) and primarily vertical or longitudinal, located in vascular zones. Rehabilitation protocols included accelerated/immediate weightbearing as tolerated (WBAT) (n = 7 studies), restricted weightbearing (n = 5 studies), and modified progressive programs (n = 1 study). Failure rates were 24.1% (accelerated WBAT), 28.3% (restricted), and 4.3% (modified progressive). PROMs (Lysholm and Tegner scores) were generally higher in accelerated WBAT protocols, with scores exceeding 85 and 7.2, respectively. Modified progressive rehabilitation yielded the lowest failure rate (4.3%) and favorable PROMs in the 1 study that utilized this method. Conclusion: The relationship between meniscal tear characteristics, repair techniques, and postoperative rehabilitation protocols plays a pivotal role in determining outcomes after isolated meniscal repair. Accelerated rehabilitation protocols may offer benefits such as faster recovery and improved patient satisfaction; nonetheless, they must be balanced against the increased risk of repair failure, particularly in complex tear patterns. Individualized rehabilitation protocols, accounting for tear characteristics, patient health, and surgical techniques, may optimize outcomes.

Background: Femoroacetabular impingement (FAI) syndrome is a common cause of hip pain in elite athletes and frequently necessitates hip arthroscopy in National Hockey League (NHL) players. While high return-to-sport (RTS) rates are reported, the long-term impact of surgery on player performance using advanced analytics has not been well studied. Hypothesis: Players undergoing surgery would exhibit steeper performance declines in defensive performance metrics relative to matched controls, despite similar RTS rates. Study Design: Cohort study; Level of evidence, 3. Methods: This matched cohort study identified NHL skaters who underwent hip arthroscopy for FAIS between 2000 and 2024 using publicly available databases. Surgical confirmation was established through ≥2 independent sports news outlets. Players active for ≥2 seasons between 2007 and 2025 were matched 1:1 to controls based on position and performance at age 24. Outcomes included Wins Above Replacement per 60 minutes (WAR/60) and offensive and defensive Goals Above Replacement per 60 minutes (Off GAR/60, Def GAR/60), obtained from Evolving-Hockey. Fixed-effects panel regression with joint F tests was used to model longitudinal aging curves and isolate surgical effects from natural performance decline. Results: A total of 63 NHL skaters (42 forwards, 21 defensemen) were included and matched to controls. Among forwards, hip arthroscopy was associated with a statistically significant decline in Def GAR/60 across the aging curve (interaction P = .04), while Off GAR/60 (P = .64) and WAR/60 (P = .40) showed no significant differences. No statistically significant performance differences were observed among defensemen. Conclusion: This study demonstrated that hip arthroscopy was associated with a steeper age-related decline in defensive performance among NHL forwards, while offensive metrics and overall player value remained unaffected. No significant performance differences were noted in defensemen. Integrating surgical history into performance models may improve player evaluation and recovery strategies.

Despite surgical reconstruction, some patients develop persistent residual rotatory laxity following anterior cruciate ligament (ACL) reconstruction (ACLR). Lateral extra-articular tenodesis (LET) has been shown to be a successful adjunctive procedure to address anterolateral instability in high-risk patients with ACL tears. It is often performed during ACLR; however, there is growing interest in understanding possible indications for the LET as an isolated procedure. To consolidate the current evidence on isolated LET (iLET) following ACLR, explore its indications, and evaluate outcomes such as laxity, patient-reported outcome (PRO) measures (PROMs), and complication rates. Systematic review; Level of evidence, 4. This systematic review was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A comprehensive literature search was performed across Ovid MEDLINE, Embase, EBM Reviews, and Emcare from inception to April 2025. Studies were eligible if they reported outcomes in patients undergoing iLET for residual laxity following ACLR with evidence of an intact ACL graft. Biomechanical, cadaveric, and non-English studies were excluded. Two reviewers independently screened studies, extracted data, and assessed methodological quality. A narrative synthesis was conducted, with descriptive statistics (frequencies, percentages, or weighted means with measures of variability) reported where appropriate. Four studies (N = 69 patients, 70 knees) were included, with a mean ± SD patient age of 25.3 ± 2.9) and follow-up period of 26.3 ± 3.6 months. Patients demonstrated significant reductions in rotatory laxity following iLET, with only 6 patients reporting positive postoperative pivot shift (grade ≥1). Reported PROMs improved across all studies. Complication rates ranged from 15.8% to 36.8% while failure rates ranged from 0% to 10.5%. This review demonstrated that iLET may provide favorable PROs, reduction in laxity, and low failure rates in patients with residual laxity following ACLR. These findings suggest that the use of iLET may be a viable option for residual laxity following ACLR with evidence of an intact ACL graft; however, a limited number of reporting studies and small sample size require these results to be interpreted with caution.

In the Arctic, shrubs are expanding and are covered by snow most of the year. Shrub branches buried in snow absorb solar radiation, reducing irradiance. This modifies the profile of radiative energy absorption in the snowpack and therefore its temperature gradient and metamorphism. Perhaps more importantly, it also reduces photochemical reaction rates and the emission of reactive and climatically active molecules to the atmosphere. No study is currently available to quantify the reduction in photochemical rates caused by shrubs buried in snow. Here, we monitor irradiance in the photochemically active range using a filter at 390 ± 125 nm in snow-covered Alnus incana (gray alders) shrubs in the boreal forest near Université Laval and on nearby grassland during a whole winter by placing light sensors at fixed heights in shrubs and on grassland and observed that irradiance in shrubs was greatly reduced. We performed radiative transfer simulations, testing the hypothesis that shrub branches behave as homogeneous absorbers such as soot. At 390 nm, dense shrub branches reduce irradiance similarly to about 140 ppb of soot. Since ice is much more absorbent at longer wavelengths, we also used a filter to monitor the 715–1000 nm wavelengths (effective 760 nm) to investigate the spectral dependence of shrub impacts on radiative energy absorption. Because of competing ice absorption at 760 nm, the effect of shrubs was much weaker than at 390 nm. We calculate that a high branch density will reduce photochemical reaction rates integrated over the whole snowpack by about a factor of 2. This may affect the composition of the lower-Arctic atmosphere in winter and spring in numerous ways, including a lower oxidative capacity, lower level of nitrogen oxides and modified secondary aerosol production. Climatic effects are expected from these compositional changes.

In epidemiologic and exposure research, biomonitoring is often used as the basis for assessing human exposure to environmental chemicals. Studies frequently rely on a single urinary measurement per participant to assess exposure to non-persistent chemicals. However, there is a growing consensus that single urine samples may be insufficient for adequately estimating exposure. The question then arises: how many samples would be needed for optimal characterization of exposure? To help researchers answer this question, we developed a tool called the Biomarker Reliability Assessment Tool (BRAT). The BRAT is based on pharmacokinetic modeling simulations, is freely available, and is designed to help researchers determine the approximate number of urine samples needed to optimize exposure assessment. The BRAT performs Monte Carlo simulations of exposure to estimate internal levels and resulting urinary concentrations in individuals from a population based on user-specified inputs (e.g., biological half-life, within- and between-person variability in exposure). The BRAT evaluates—through linear regression and quantile classification—the precision/accuracy of the estimation of internal levels depending on the number of urine samples. This tool should guide researchers towards more robust biomonitoring and improved exposure classification in epidemiologic and exposure research, which should in turn improve the translation of that research into decision-making.

This paper is a state-of-the-art review of computational damage and fracture mechanics methods applied to model ductile fracture at the microscale. An emphasis is made on robust and stable methods that can handle heterogeneous structures, large deformations, and cracks initiation and coalescence. Ductile materials’ microstructures feature brittle and ductile components whose heterogeneous behavior can give raise to cracks initiation due to stress concentration. Due to large deformations, cracks initiated by brittle components failure transform into large voids. These major voids interact and coalesce by plastic localization within ductile components and lead to final failure. This process can involve minor voids nucleated directly within ductile components at sub-micron scales. State-of-the-art discontinuous approaches can be applied to discretize accurately brittle components and model their failure, given that large deformations can be handled. For ductile components, continuous approaches are discussed in this review as they can model the homogenized influence of minor voids, hence alleviating the burden and computational cost overhead that an explicit discretization of those voids would require. Close to final failure, when major voids are coalescing, and the influence of minor voids becomes comparable to that of major voids, the transition from a continuous damage process within ductile components to the initiation and propagation of discontinuous cracks within these components has to be modeled. This review ends with a discussion on computational methods that have successfully been applied to model the continuous-discontinuous transition, and that could be coupled to discontinuous approaches in order to model ductile fracture at the microscale in its full three-dimensional complexity.

A lasting legacy of the International Polar Year (IPY) 2007–2008 was the promotion of the Permafrost Young Researchers Network (PYRN), initially an IPY outreach and education activity by the International Permafrost Association (IPA). With the momentum of IPY, PYRN developed into a thriving network that still connects young permafrost scientists, engineers, and researchers from other disciplines. This research note summarises (1) PYRN’s development since 2005 and the IPY’s role, (2) the first 2015 PYRN census and survey results, and (3) PYRN’s future plans to improve international and interdisciplinary exchange between young researchers. The review concludes that PYRN is an established network within the polar research community that has continually developed since 2005. PYRN’s successful activities were largely fostered by IPY. With >200 of the 1200 registered members active and engaged, PYRN is capitalising on the availability of social media tools and rising to meet environmental challenges while maintaining its role as a successful network honouring the legacy of IPY.

Progress in defining genomic fitness landscapes in cancer, especially those defined by copy number alterations (CNA), has been impeded by lack of time series single cell sampling of polyclonal populations and temporal statistical models1–7. Here, we generated 42,000 genomes from multi-year time series single cell whole genome sequencing (scWGS) of breast epithelium and primary triple negative breast cancer (TNBC) patient derived xenografts (PDX), revealing the nature of CNA defined clonal fitness dynamics induced by TP53 mutation and cisplatin chemotherapy. Using a new Wright-Fisher population genetics model8,9 to infer clonal fitness, we found that TP53 mutation alters the fitness landscape, reproducibly distributing fitness over a larger number of clones associated with distinct CNAs. Furthermore, in TP53 mutant TNBC PDX models, inferred fitness coefficients from CNA-based genotypes accurately forecast experimentally enforced clonal competition dynamics. Drug treatment in three long-term serially passaged TNBC PDX resulted in cisplatin resistant clones emerging from low fitness phylogenetic lineages in the untreated setting. Conversely, high fitness clones from treatment naive controls were eradicated, signaling an inversion of the fitness landscape. Finally, upon release of drug selective pressure dynamics were reversed, indicating a fitness cost of treatment resistance. Taken together, our findings define clonal fitness linked to both CNA and therapeutic resistance in polyclonal tumours.

When the original article was first published the given name and family names of Francophone Group for Enhanced Recovery After Surgery (GRACE) individually cited within the author list were inadvertently interchanged. The author list are correctly cited in this Correction.