Self-assembled nanocomposites of high water content and load-bearing capacity.

Biological tissues, such as cartilage, tendon, ligament, skin, and plant cell wall, simultaneously achieve high water content and high load-bearing capacity. The high water content enables the transport of nutrients and wastes, and the high load-bearing capacity provides structural support for the organisms. These functions are achieved through nanostructures. This biological fact has inspired synthetic mimics, but simultaneously achieving both functions has been challenging. The main difficulty is to construct nanostructures of high load-bearing capacity, characterized by multiple properties, including elastic modulus, strength, toughness, and fatigue threshold. Here we develop a process that self-assembles a nanocomposite using a hydrogel-forming polymer and a glass-forming polymer. The process separates the polymers into a hydrogel phase and a glass phase. The two phases arrest at the nanoscale and are bicontinuous. Submerged in water, the nanocomposite maintains the structure and resists further swelling. We demonstrate the process using commercial polymers, achieving high water content, as well as load-bearing capacity comparable to that of polyethylene. During the process, a rubbery stage exists, enabling us to fabricate objects of complex shapes and fine features. We conduct further experiments to discuss likely molecular origins of arrested phase separation, swell resistance, and ductility. Potential applications of the nanocomposites include artificial tissues, high-pressure filters, low-friction coatings, and solid electrolytes.

Integrated Probe System for Measuring Soil Carbon Dioxide Concentrations.

This article outlines the design and implementation of an internet-of-things (IoT) platform for the monitoring of soil carbon dioxide (CO2) concentrations. As atmospheric CO2 continues to rise, accurate accounting of major carbon sources, such as soil, is essential to inform land management and government policy. Thus, a batch of IoT-connected CO2 sensor probes were developed for soil measurement. These sensors were designed to capture spatial distribution of CO2 concentrations across a site and communicate to a central gateway using LoRa. CO2 concentration and other environmental parameters, including temperature, humidity and volatile organic compound concentration, were logged locally and communicated to the user through a mobile (GSM) connection to a hosted website. Following three field deployments in summer and autumn, we observed clear depth and diurnal variation of soil CO2 concentration within woodland systems. We determined that the unit had the capacity to log data continuously for a maximum of 14 days. These low-cost systems have great potential for better accounting of soil CO2 sources over temporal and spatial gradients and possibly flux estimations. Future testing will focus on divergent landscapes and soil conditions.

Incidence of Septic Arthritis After Vancomycin Soaking of the Graft During Arthroscopic Anatomic Anterior Talofibular Ligament and Calcaneofibular Ligament Reconstruction.

Background: Vancomycin soaking of the graft during arthroscopic anterior cruciate ligament reconstruction has been shown to be effective in reducing the rate of postoperative infection. Purpose/Hypothesis: The present study aimed to (1) analyze the effect of vancomycin-soaked grafts during arthroscopic anatomic reconstruction of the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL) on the incidence of infection and (2) evaluate the influence of infection on functional outcomes and identify the risk factors of infection. It was hypothesized that vancomycin soaking of the graft would reduce the postoperative infection rate. Study Design: Cohort study; Level of evidence, 3. Methods: Consecutive patients at 2 centers who underwent ATFL/CFL reconstruction between December 2011 and July 2022 were included. All patients had undergone anterolateral arthroscopic debridement of the ankle and anatomic ATFL/CFL reconstruction with a gracilis tendon autograft. Vancomycin soaking of the graft was begun in both centers in January 2021. Complications, functional scores, return to sports (RTS) rates, and the level of return were compared between patients with and without vancomycin-soaked grafts and between patients with and without infection. Results: Overall, 182 patients (48% men; mean age, 34 ± 11.9 years) were included, with a mean follow-up of 23 ± 16.1 months. The rate of postoperative infection was significantly lower in the group with vancomycin soaking versus without (0/92 [0%] vs 8/90 [8.9%]; P = .001). At the final follow-up, there were 26 complications (14.3%): 8 infections, 6 recurrent tears, and 12 peripheral neuropathies. The infections developed after a mean of 17 ± 11 days. The functional scores were excellent at the final follow-up (American Orthopaedic Foot and Ankle Society [AOFAS] Ankle-Hindfoot Score, 86.5 ± 18.7; Karlsson score, 85 ± 18.3). Patients with infection had significantly decreased AOFAS scores (52.8 ± 27.6 vs 83.3 ± 21.5; P = .003), Karlsson scores (57 ± 27.7 vs 83.6 ± 20; P = .006), and RTS rates (25% vs 77%; P = .005) versus patients without infection. Conclusion: Vancomycin-soaked grafts for arthroscopic anatomic ATFL/CFL reconstruction decreased the rate of postoperative infection. Infection led to a deterioration in results. Vancomycin-soaking of the graft did not have a negative effect on functional results.

Validation of the Parisian Hamstring Avulsion Score (PHAS) in the Evaluation and Follow-up of Patients Operated for Proximal Hamstring Avulsion.

BACKGROUND: No validated score is available for the prediction of return to sport (RTS) after proximal hamstring avulsion (PHA) surgery. PURPOSE: To validate a new assessment tool for patients after PHA surgery: the Parisian Hamstring Avulsion Score (PHAS). STUDY DESIGN: Cohort study (Diagnosis); Level of evidence, 3. METHODS: All patients at our clinic who had surgery for PHA between January 2015 and March 2018 were included in this study. A suspected clinical diagnosis of PHA was confirmed by magnetic resonance imaging. PHA was repaired by surgical reinsertion with suture anchors. Minimum postoperative follow-up was 2 years, and the PHAS, University of California, Los Angeles (UCLA), score, and Tegner score were used. The PHAS is a patient-reported outcome measure, evaluating the effect of PHA injury with 9 items. It was validated by calculating its psychometric properties, and then correlation analysis was performed to determine the relationship between the PHAS, UCLA score, and Tegner score. Cutoff values for the prediction of RTS were determined. RESULTS: A prospective case series study was performed. A total of 156 patients were included. Median age (first quartile; third quartile) was 54.2 years (44.7 years; 61.3 years), and the mean ± SD time of the final follow-up was 69 ± 11.6 months. Two years after surgery, 66.7% (n = 104) of patients were able to RTS. A strong correlation was noted between all 3 scores at 1 year postoperatively. Overall internal consistency was high, with a Cronbach alpha coefficient of 0.86. The intraclass correlation coefficient was 0.96, showing excellent reliability. The minimal detectable change was 12.9. No patients reached the maximum score at 2 years. Analysis of the receiver operating characteristic curves of the 3 scores at postoperative 9 months in relation to the RTS at 1 and 2 years showed area under the curve values of >0.7, indicating significant discriminant capacity for the RTS. A PHAS cutoff value of 86 at 9 months for the prediction of RTS at postoperative 1 year had a sensitivity of 65.6% (95% CI, 53.7%-77.5%) and a specificity of 81.4% (95% CI, 69.8%-93%). CONCLUSION: PHAS is a valid and reliable tool for follow-up after PHA surgery. It also offers a simple way to predict RTS.

Descriptive analysis of pediatric orthopedic surgical emergencies during the COVID-19 lockdown: Single-center observational study in a pandemic red-zone area in France.

INTRODUCTION: Lockdown involved strict confinement of children at home, radically affecting their way of life, with increased risk of domestic accidents and the temptation to step outside of the legal framework. The aim of the present study was to analyze the impact of lockdown on pediatric emergency turnover in a university reference center situated in a high-risk "red zone" and to describe specific management measures. HYPOTHESIS: Pediatric emergency turnover and the corresponding lesion mechanisms were altered by lockdown. MATERIALS AND METHODS: All children undergoing emergency orthopedic surgery during lockdown (group 1) were prospectively included, then retrospectively compared to series operated on during the same period in the previous 3 years. Demographic and surgical data were analyzed, and the pathway changes that were developed were detailed. RESULTS: Turnover fell by a mean 33.5%, without change in indications. The most frequent lesions were wounds (54.3%), followed by fractures (34.3%) and infections (11.4%); the upper limbs were involved in 84.6% of cases. Lockdown had been infringed in 9.7% of traumas, mainly concerning fractures (55%). Postoperative management was modulated during lockdown in 34% of cases, without complications at the time of writing. DISCUSSION: Pediatric emergency turnover decreased, without major change in lesion mechanisms. Accidents associated with lockdown infringement were rare (<10%), demonstrating good adaptation on the part of these children living in an urban area. The adapted care pathway was beneficial, and will no doubt continue to optimize management in future, with accelerated circuits and use of telemedicine. LEVEL OF EVIDENCE: IV, comparative retro-prospective study.

S2-Alar-iliac screw fixation for paediatric neuromuscular scoliosis: Preliminary results after two years.

BACKGROUND: Correcting pelvic obliquity is among the main goals of surgery for neuromuscular scoliosis. Spino-pelvic fixation must be stable and capable of withstanding the considerable mechanical forces applied at the lumbo-sacral junction. Selection of the best anchoring option is therefore crucial. S2-alar-iliac (S2AI) screws, which are used in adults, are less often chosen in the French paediatric spinal-surgery community. The objective of this study was to report our preliminary experience with S2AI screws used in the treatment of paediatric patients with neuromuscular scoliosis. HYPOTHESIS: Pelvic anchoring by means of S2AI screws is reliable and technically feasible in non-ambulatory children with neuromuscular scoliosis. MATERIALS AND METHODS: Consecutive non-ambulatory patients who underwent scoliosis surgery with S2AI screw fixation to the pelvis between 2016 and 2018 were retrospectively included. The surgical procedure consisted in either posterior spinal fusion (PSF) or magnetic growing rod (MGR) implantation. In all patients, radiographs were obtained before surgery, within 3 months after surgery, and at last follow-up; and low-dose computed tomography (CT) was performed before and after surgery. RESULTS: We included 25 patients with a mean age of 13.8±4.0 years, 18 managed by PSF and 7 by MGRs. Screw diameters ranged from 7.5 to 9.5mm and all screws were at least 60mm in length. The diameters and lengths were the same on both sides in 16 (89%) patients in the PSF group and in all patients in the MGR group. At last follow-up after a mean of 35.5±3.0 months, pelvic obliquity was corrected in all 23 patients with this abnormality before surgery. Complications consisted of lateral cortical screw breakthrough in 8 (32% of screws) patients and screw malposition in 2 (8% of screws) patients. No clinically significant complications related to the fixation material were recorded. DISCUSSION: The results of our study demonstrate the feasibility of S2AI screw fixation in paediatric patients with neuromuscular scoliosis. Pelvic asymmetry and dysmorphism do not contra-indicate the procedure but must be evaluated before surgery. Further work is needed to assess the potential long-term consequences on pain and growth of screw passage through the sacro-iliac joints. LEVEL OF EVIDENCE: IV, retrospective study.