Anterior cruciate ligament injury should not be considered a contraindication for medial unicompartmental knee arthroplasty: Finite element analysis.

PURPOSE: The research objective of this study is to use finite element analysis to investigate the impact of anterior cruciate ligament (ACL) injury on medial unicompartmental knee arthroplasty (UKA) and explore whether patients with ACL injuries can undergo UKA. METHODS: Based on the morphology of the ACL, models of ACL with diameters ranging from 1 to 10mm are created. Finite element models of UKA include ACL absence and ACLs with different diameters. After creating a complete finite element model and validating it, four different types of loads are applied to the knee joint. Statistical analysis is conducted to assess the stress variations in the knee joint structure. RESULTS: A total of 11 finite element models of UKA were established. Regarding the stress on the ACL, as the diameter of the ACL increased, when a vertical load of 750N was applied to the femur, combined with an anterior tibial load of 105N, the stress on the ACL increased from 2.61 MPa to 4.62 MPa, representing a 77.05% increase. Regarding the equivalent stress on the polyethylene gasket, a notable high stress change was observed. The stress on the gasket remained between 12.68 MPa and 14.33 MPa in all models. the stress on the gasket demonstrated a decreasing trend. The equivalent stress in the lateral meniscus and lateral femoral cartilage decreases, reducing from the maximum stress of 4.71 MPa to 2.61 MPa, with a mean value of 3.73 MPa. This represents a reduction of 44.72%, and the statistical significance is (P < 0.05). However, under the other three loads, there was no significant statistical significance (P > 0.05). CONCLUSION: This study suggests that the integrity of the ACL plays a protective role in performing medial UKA. However, this protective effect is limited when performing medial UKA. When the knee joint only has varying degrees of ACL injury, even ACL rupture, and the remaining structures of the knee joint are intact with anterior-posterior stability in the knee joint, it should not be considered a contraindication for medial UKA.

Increasing sensitivity of dryland water use efficiency to soil water content due to rising atmospheric CO2.

Examining the intricate interplay between ecosystem carbon-water coupling and soil moisture sensitivity serves as a crucial approach to effectively assess the dilemma arising from escalating global carbon emissions and concomitant water scarcity. Using the Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ), this study investigated the potential effects of climate change and soil water content (SWC) on terrestrial ecosystem water use efficiency (WUE) across China from 1982 to 2060. The results revealed that: (1) WUE was higher in South China and Northeast China, but lower in Northwest China and it had shown a significant upward trend in the past 40 years, especially in Northwest China where grasslands were widely distributed. The increase in WUE was mainly closely related to the greening of vegetation. In the past 40 years, the area of net primary productivity (NPP), evapotranspiration (ET), and WUE showing an upward trend accounted for 85.85 %, 63.66 %, and 83.88 % of the total area of the country, respectively. Although ET also showed an increasing trend nationwide, the increase of NPP was more obvious; (2) The control experiment showed that WUE showed a significant increase trend in arid and semi-arid areas of Northwest China with the increase of CO2 concentration, while SWC showed a significant drying trend, but both WUE and SWC showed an increasing trend in humid areas. The sensitivity of WUE to SWC was enhanced in arid and semi-arid areas, and the effect of soil drought was partially offset by the increase of WUE; (3) Future climate projections also indicated that the CO2 fertilization effect will contribute to an increase in WUE while causing drier soil moisture conditions in the arid and semi-arid regions. Especially under the SSP5-8.5 scenario, CO2 fertilization in Northwest China contributed more than 14 % to WUE from 2015 to 2060, while the impact on SWC depletion exceeded 3 %. This highlights the potential implications of rising atmospheric CO2 concentration, as it may promote a significant rise in WUE and exacerbate the drying of soil moisture in these areas. These findings emphasize the need for careful attention and consideration in managing water resources in arid and semi-arid regions in the face of future climate change.

Effect of the altitudinal climate change on growing season length for deciduous broadleaved forest in southwest China.

The altitudinal changes of plant phenology in response to climate change remain poorly understood in subtropical mountain areas. Using the satellite phenology and climate dataset (temperature, precipitation and solar radiation) from 2001 to 2016 in southwest China, we analyzed the spatiotemporal changes of climate and phenological characteristics of the growing season length (LOS), start of the growing season (SOS) and end of the growing season (EOS) for the deciduous broadleaf forest (DBF). Results show that LOS was shortened by 25 and 15.2 days/km rise in elevation, respectively, using two regression methods based on "Hopkins' bioclimatic law" (expressing LOS as a function of altitude, latitude and longitude) and altitudinal mean annual LOS. The majority of the shortened LOS towards high elevations was attributed to the postponed SOS and the advanced EOS as the elevation is higher and lower than 2.2-2.3 km, respectively. The recent climate warming has significantly prolonged LOS in the entire DBF area. This increase in LOS differs with altitude due to altitudinal heterogeneity of climate change. In the cold high mountain environment, changes of phenological parameters are more sensitive to climate warming, characterized by a significantly advanced SOS, postponed EOS and prolonged LOS driven by spring and autumn warming. In the warm environment of the low elevation areas, changes of phenological parameters are relatively smaller even though the temperature rise is greater than that in the cold high mountains. Furthermore, winter wetting can significantly weaken the advanced SOS and prolonged LOS at lower elevations in the warm south, but winter drying and declining solar radiation in spring can enhance the advanced SOS and prolonged LOS at the extremely high elevations in the cold north. These results highlight the critical need to include altitudinal heterogeneity when assessing phenological changes from remote sensing platforms.