The degree of fracture reduction does not compromise the clinical efficacy of arthroscopic reduction and fixation of tibial posterior cruciate ligament avulsion fractures: A retrospective study.

This study aimed to explore the postoperative outcomes of patients who underwent arthroscopic internal fixation with repositioning sutures for the treatment of posterior cruciate ligament (PCL) avulsion fractures with poorly reduced fracture fragments. It was hypothesized that improperly repositioned fracture fragments might not influence the postoperative clinical outcomes in patients with PCL avulsion fractures treated by arthroscopic sutures. From January 2020 to December 2021, patients admitted to our hospital with PCL avulsion fractures were evaluated. Our inclusion criteria were as follows: diagnosis of PCL avulsion fracture as Meyers & McKeever Type II or Type III; underwent arthroscopic double tunnel suture fixation; and age below 70. Of the patients meeting these criteria, data from 34 individuals were collected by a designated follow-up officer. Based on postoperative imaging, the patients were divided into 2 groups: well fracture reduction and poor fracture reduction groups. Prior to the surgery, the Lysholm score, knee mobility, and international knee documentation committee (IKDC score) were recorded for both groups. At the 3-month post-surgery mark, CT-3D reconstruction was performed. Statistical analysis was conducted on the collected data. For data that conformed to a normal distribution, the t test was applied. For data that didn't conform, we used a non-parametric test. Both groups achieved successful wound healing without encountering any adverse events, such as fracture nonunion infection. Fracture healing was observed in both groups at the 3-month postoperative mark. The average follow-up duration was 13.24 ± 6.18 months. There were no significant differences in Lysholm score, IKDC score, or knee mobility between the well- and poorly-reduced groups at the final follow-up (P > .05). Postoperatively, both groups demonstrated significant improvements in knee function compared to the preoperative scores, with statistically significant differences observed in Lysholm score, IKDC score, and knee mobility (P < .05). Arthroscopic fixation with double-tunnel sutures proved to be a highly effective treatment approach for PCL avulsion fractures, even in cases where the fractures were poorly reduced. Remarkably, there were no significant differences observed in postoperative knee function between the well- and poorly-reduced groups, indicating that both groups achieved favorable outcomes.

Determination of nitrogen sources and losses in surface runoff from different lands at a watershed scale.

Nitrogen (N) loss by surface runoff inevitably results in severe N pollution and eutrophication of aquatic ecosystems. In this study, surface runoff from different land uses in the East Tiaoxi River watershed was collected, and the N concentrations, sources and losses were measured using the dual isotope (δ15N-NO3- and δ18O-NO3-), a Bayesian isotopic mixing (SIAR) model and Soil Conservation Service Curve Number (SCS-CN) method. The results showed that the N concentrations in surface runoff from agricultural lands were higher than those from urban areas and forestlands, and nitrate (NO3-), particulate nitrogen (PN) and dissolved organic nitrogen (DON) were the major forms of N in surface runoff in the East Tiaoxi River watershed. The total loss rate of total nitrogen (TN) from surface runoff in the East Tiaoxi River watershed was 5.38 kg·ha-1·a-1, with NO3--N (46%) contributing the most to TN loss. The TN, and NO3--N loss rates in surface runoff from tea planting lands (21.08 kg·ha-1·a-1, 11.98 kg·ha-1·a-1) and croplands (16.93 kg·ha-1·a-1, 10.96 kg·ha-1·a-1) were high, those from vegetable lands and urban areas were medium, and those from economic and natural forestlands were low in the East Tiaoxi River watershed. The NO3--N contributions of chemical fertiliser (CF), soil N (SN), sewage/manure (SM), and atmospheric deposition (AD) in surface runoff in the East Tiaoxi River watershed were 124.32 × 103, 104.84 × 103, 82.25 × 103 and 58.69 × 103 kg·a-1, respectively. The N pollutant losses in surface runoff from agricultural lands (croplands with rice growing, vegetable lands and tea planting lands) were responsible for most of the N pollutants being transported into the East Tiaoxi River systems.

Combining dual isotopes and a Bayesian isotope mixing model to quantify the nitrate sources of precipitation in Ningbo, East China.

Nitrate (NO3-) is becoming a significant contributor to acid deposition in many cities in China. Based on the chemical compositions and stable isotopes of NO3- in precipitation (δ15N-NO3- and δ18O-NO3-), the NO3- sources and their formation pathways were determined to aid in reducing NOx emissions in Ningbo, an important port city. The acid rain frequency in Ningbo was 67%, and the mean SO42-/NO3- ratio was 1.07. The δ18O-NO3- (49.5‰-82.8‰) and δ15N-NO3- values (-4.3‰-2.7‰) both varied seasonally, with high values during the cold season and low values during the warm season. The seasonal variations in the δ18O-NO3- values were mainly controlled by the NO3- formation pathways, following the OH· pathway during the warm season and N2O5 pathway during the cold season. The Monte Carlo simulation results indicated that the contributions of the OH· pathway ranged from 28.3% to 75.4%, with the remainder contributed by the N2O5 pathway. The improved Bayesian model incorporating nitrogen (N) isotopic fractionation (Ԑ = 4‰) indicated that mobile sources, including ship emissions (35.0%) > coal combustion (26.0%) > biomass burning (20.0%) > soil emissions (19.0%), were the major sources of NOx emissions in Ningbo. The results indicate that the influence of isotopic fractionation on source apportionment must be considered in a Bayesian model.