654 research outputs found
The chemical evolution of self-gravitating primordial disks
Numerical simulations show the formation of self-gravitating primordial disks
during the assembly of the first structures in the Universe, in particular
during the formation of Pop.~III and supermassive stars. Their subsequent
evolution is expected to be crucial to determine the mass scale of the first
cosmological objects, which depends on the temperature of the gas and the
dominant cooling mechanism. Here, we derive a one-zone framework to explore the
chemical evolution of such disks and show that viscous heating leads to the
collisional dissociation of an initially molecular gas. The effect is relevant
on scales of 10 AU (1000 AU) for a central mass of 10 M_sun (10^4 M_sun) at an
accretion rate of 10^{-1} M_sun yr^{-1}, and provides a substantial heat input
to stabilize the disk. If the gas is initially atomic, it remains atomic during
the further evolution, and the effect of viscous heating is less significant.
The additional thermal support is particularly relevant for the formation of
very massive objects, such as the progenitors of the first supermassive black
holes. The stabilizing impact of viscous heating thus alleviates the need for a
strong radiation background as a means of keeping the gas atomic.Comment: 13 pages, 5 figures, 6 tables, accepted at A&
Loss of chondroprotection of medial collagen meniscus implant (CMI) at 20-year follow-up
Objective: The mid-term results of the collagen meniscus implant (CMI) procedure for the replacement of partial meniscus defects have already been described. However, there is a paucity of long-term comparative studies. This study aimed to compare the clinical outcomes, failures, and osteoarthritis progression of patients who underwent partial medial meniscectomy and medial CMI implantation. Methods: Thirty-six nonconsecutive patients with medial meniscus injuries that underwent medial CMI (MCMI) implantation or partial medial meniscectomy (PMM) between 1997 and 2000 were included in a prospective study with an intermediate 10-year follow-up examination and a final follow-up examination at 20-year follow-up. Outcome measures at the 20-year follow-up included the Lysholm score, visual analogue scale (VAS) for pain, International Knee Documentation Committee (IKDC) knee form , and Tegner activity level. Bilateral weight-bearing radiographs were also performed to evaluate hip-knee-angle (HKA) and the medial joint line height (JL). Data regarding complications and failures were also collected. Results: At the 20-year follow-up, 31 patients (83% follow-up rate) with a mean age of 60.7 ± 8.9 years were included in the final analysis (21.1 ± 1.2 years follow-up). Four reoperations and one failure per group were reported. When comparing the clinical results of the two groups, no difference was found considering the Lysholm score, Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner, and the IKDC. Moreover, 20 patients underwent radiographic examination (10 MCMI, 10 MM), and no statistically significant difference was reported concerning the JL, HKA, and the presence and incidence of osteoarthritis between the two groups. Conclusion: The CMI implant for partial medial meniscectomy provided good long-term results and a low failure rate. However, differently from the 10 years follow-up, the clinical and the radiological outcomes were not superior compared to the medial meniscectomy group. The present study's result suggests that using a medial scaffold is not chondroprotective. Level of evidence: III, Prospective case-control study
Obsessive–Compulsive Disorder Comorbidity: Clinical Assessment and Therapeutic Implications
Obsessive–compulsive disorder (OCD) is a neuropsychiatric disorder affecting approximately 1–3% of the population. OCD is probably an etiologically heterogeneous condition. Individuals with OCD frequently have additional psychiatric disorders concomitantly or at some time during their lifetime. Recently, some authors proposed an OCD sub-classification based on comorbidity. An important issue in assessing comorbidity is the fact that the non-response to treatment often involves the presence of comorbid conditions. Non-responsive patients are more likely to meet criteria for comorbid axis I or axis II disorders and the presence of a specific comorbid condition could be a distinguishing feature in OCD, with influence on the treatment adequacy and outcome
Surgical technique: posterior cruciate ligament (PCL) reconstruction using double posteromedial arthroscopic portals
The posterior cruciate ligament (PCL) reconstruction is a technically demanding surgical procedure that requires optimal identification of both the femoral and the tibial anatomical footprints. To aid the tibial tunnel placement and many authors recommend creating a posteromedial (PM) portal. The further addition of a second PM portal, which could be used as a "working portal", may further allow a more straightforward reconstruction by improving the identification of the anatomical footprint, the clearing of the stump, and the graft passage
Risk Factors Affecting the Survival Rate of Collagen Meniscal Implant for Partial Meniscal Deficiency: An Analysis of 156 Consecutive Cases at a Mean 10 Years of Follow-up
Background: Collagen meniscal implant (CMI) is a biologic scaffold that can be used to replace meniscus host tissue after partial meniscectomy. The short-term results of this procedure have already been described; however, little is known about risk factors for failure. Purpose: To determine the factors that predict failure of meniscal scaffold implantation in a large series of patients treated at a single institution and to better define the indications for surgery. Study Design: Case-control study; Level of evidence, 3. Methods: The analysis included 186 consecutive patients with a minimum 5-year follow-up who underwent CMI scaffold implantation or combined procedures. Patients' characteristics and details of the surgery were obtained via chart review. Patients with a Lysholm score Results: The final analysis included 156 patients (84%) at a mean follow-up of 10.9 +/- 4.3 years. The patients' mean age at surgery was 42.0 +/- 11.1 years, and the survival rate was 87.8%. Subgroup analysis identified Outerbridge grade 3-4 (Hazard ratio [HR], 3.8; P = .004) and a lateral meniscal implant (HR, 3.2; P = .048) as risk factors for failure. The survival rate was 90.4% for medial implants and 77.4% for lateral implants. An Outerbridge grade 3-4 (HR, 2.8; P < .001) and time from meniscectomy to scaffold >10 years (HR, 2.8; P = .020) were predictive of surgical or clinical failure. Conclusion: CMI for partial meniscal deficiency provided good long-term results, with 87.8% of the implants still in situ at a mean 10.9 years of follow-up. Outerbridge grade 3-4, lateral meniscal implants, and longer time from the meniscectomy to implantation of the CMI were identified as risk factors for clinical and surgical failure
High survivorship rate and good clinical outcomes after high tibial osteotomy in patients with radiological advanced medial knee osteoarthritis: a systematic review
IntroductionThe role of valgus producing high tibial osteotomy (HTO) for the treatment of advanced knee osteoarthritis (OA) is still controversial. The aim of the current systematic review was to assess survivorship and patient-reported outcomes (PROMs) of high tibial osteotomy in patients with radiological advanced medial knee OA.MethodsA systematic search of PubMed, Cochrane and EMBASE database was performed in July 2023 in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines. Inclusion and exclusion criteria were applied to identify studies investigating the survivorship rate and PROMs of valgus-producing high tibial osteotomy in patients with advanced knee OA at x-ray assessment in the medial compartment at minimum-two-years follow up. Advanced radiological OA was defined as Kellgren Lawrence (K-L) >= 3 or Ahlbach >= 2. Survivorship was defined as percentage of patients free of total knee arthroplasty (TKA) at follow-up. Clinical interpretation of provided PROMs were performed according to minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) target values reported in literature. Survivorship data and PROMs scores were extracted, and studies were stratified based on selected study features. The quality of included studies was assessed with modified Coleman score.ResultsA total of 18 studies, totalling 1296 knees with a mean age between 46.9 and 67 years old, were included. Average survivorship was of 74.6% (range 60 - 98.1%) at 10-years follow up. The subjective scoring systems showed good results according to MCID and PASS, and postoperative improvements were partially maintained until final follow-up.ConclusionHTO is worth considering as treatment choice even in patients affected by radiological advanced medial knee osteoarthritis. Long term survivorship and good patient reported clinical outcomes could be expected in this population.Level of evidenceIV; systematic review of level III-IV studies
Good long-term patients reported outcomes, return-to-work and return-to-sport rate and survivorship after posterior cruciate ligament (PCL)-based multiligament knee injuries (MLKI) with posteromedial corner tears as significant risk factor for failure
Altres ajuts: acords transformatius de la UABTo assess the survival rate and associated risk factors of a wide cohort of patient's underwent surgical treatment for posterior cruciate ligament (PCL)-based multiligament knee injury (MLKI) at long-term follow-up and to investigate the long-term patient's reported outcomes (PROMS) and functional activity. All cases of PCL-based MLKI performed at one single sport-medicine institution were extracted and patient's with a minimum 2 years of follow-up included. VAS, Lysholm, KOOS, Tegner Activity level scores, the incidence and time of return to sport (RTS) and return to work (RTW) were collected before, after surgery and at final follow-up. A multivariate logistic regression was performed to investigate the outcomes associated with the patient's acceptable symptoms state (PASS) for each sub-score of the KOOS. The Kaplan-Meier method with surgical failure (re-operation to one of the reconstructed ligaments) as endpoint was used to perform the survivorship analysis for the entire cohort. Forty-two patients were included and evaluated at an average of 10 years. All PROMS significantly improved from pre- to post-surgery (range η 2 0.21-0.43, p < 0.05) except for the Tegner score which significantly improved from pre-surgery and to final follow-up (η 2 = 0.67, p < 0.001). RTW was achieved in the 95.2% after 2.4 ± 1.9 months. RTS was achieved in 78.6% after 6.7 ± 5.0 months. The higher number of surgeries were the significant negative predictors of PASS for the KOOS sub-scales Sport (p = 0.040) and Quality of Life (p = 0.046), while the presence of meniscal lesions was a significant negative predictor of PASS only for the KOOS sub-scale of Sport (p = 0.003). Six patients (14.3%) underwent reoperation and were considered as surgical failures. The global survivorship was 95.2%, 92.6%, 87.1%, and 74.7% at 2, 5, 12, and 15 years, respectively. The survivorship in patient undergoing PMC reconstruction surgery was significantly lower (p = 0.004; HR 7.1) compared to patients without a PMC lesion. Good-to-excellent PROMS could be obtained and maintained at long-term follow-up after surgery, with the higher number of surgeries and meniscal lesions as significant negative predictors of the PASS. Moreover, the presence of a PMC lesion significantly increases the risk of the PCL reconstruction failure. III
Custom-Made Devices Represent a Promising Tool to Increase Correction Accuracy of High Tibial Osteotomy: A Systematic Review of the Literature and Presentation of Pilot Cases with a New 3D-Printed System
Background: The accuracy of the coronal alignment corrections using conventional high tibial osteotomy (HTO) falls short, and multiplanar deformities of the tibia require consideration of both the coronal and sagittal planes. Patient-specific instrumentations have been introduced to improve the control of the correction. Clear evidence about customized devices for HTO and their correction accuracy lacks. Methods: The databases PUBMED and EMBASE were systematically screened for human and cadaveric studies about the use of customized devices for high tibial osteotomy and their outcomes concerning correction accuracy. Furthermore, a 3D-printed customized system for valgus HTO with three pilot cases at one-year follow-up was presented. Results: 28 studies were included. The most commonly used custom-made devices for HTO were found to be cutting guides. Reported differences between the achieved and targeted correction of hip-knee-ankle angle and the posterior tibial slope were 3 degrees or under. The three pilot cases that underwent personalized HTO with a new 3D-printed device presented satisfactory alignment and clinical outcomes at one-year follow-up. Conclusion: The available patient-specific devices described in the literature, including the one used in the preliminary cases of the current study, showed promising results in increasing the accuracy of correction in HTO procedure
May Measurement Month 2019: an analysis of blood pressure screening results from Italy
: Cardiovascular (CV) diseases are burdened by high mortality and morbidity, being responsible for half of the deaths in Europe. Although hypertension is recognized as the most important CV risk factor, hypertension awareness, and blood pressure (BP) control are still unsatisfactory. In 2017 and 2018, respectively >10 000 and >5000 individuals took part in the May Measurement Month (MMM) campaign in Italy, of whom 30.6% and 26.3% were found to have high BP, respectively. To raise public awareness on the importance of hypertension and to collect BP data on a nation-wide scale in Italy. In the frame of the MMM campaign, an opportunistic cross-sectional survey of volunteers aged ≥18 years was carried out in May 2019. BP measurement, the definition of hypertension, and statistical analysis followed the standard MMM protocol. Screening was conducted in multiple sites by health personnel. Among the 10 182 people screened (females: 52.3%, mean age 58 ± 16years) mean BP was 127/78 mmHg, and 3171 (31.1%) participants had arterial hypertension, of whom 62.1% were aware of being hypertensive. Diabetes, body mass index >25 kg/m2 were associated with higher BP and previous myocardial infarction with lower BP. For the third consecutive year we collected a nation-wide snapshot of BP control in a large sample of individuals. The high participation, with some yearly fluctuations likely due to the limitations of the sampling technique, confirms the power of this kind of health campaign in reaching a significant number of people to raise awareness on health topics
- …