Time course of muscle activation, energetics and mechanics of running in minimalist and traditional cushioned shoes during level running.

The study aimed to compare the ankle muscles activation, biomechanics and energetics of running in male runners during submaximal level run using minimalist (MinRS) and traditional cushioned (TrdRS) running shoes. During 45-min running in MinRS and TrdRS, the ankle muscles pre- and co-activation, biomechanics, and energetics of running of 16 male endurance runners (25.5 ± 3.5 yr) were assessed using surface electromyography (tibialis anterior and gastrocnemius lateralis), instrumented treadmill and indirect calorimetry, respectively. The net energy cost of running (Cr) was similar for both conditions (P = 0.25) with a significant increase over time (P < 0.0001). Step frequency (P < 0.001), and total mechanical work (P = 0.001) were significantly higher in MinRS than in TrdRS with no evolution over time (P = 0.28 and P = 0.85, respectively). The ankle muscles pre- and co-activation during the contact phase did not differ between the two shoe conditions (P ≥ 0.33) or over time (P ≥ 0.15). In conclusion, during 45-min running, Cr and muscle pre- and co-activation were not significantly different between MinRS and TrdRS with significantly higher step frequency and total mechanical work noted in the former than in the latter. Moreover, Cr significantly increased during the 45-min trial in both shoe conditions along with no significant change over time in muscle activation and biomechanical variables.

[Partial knee arthroplasty - Which parameters to consider for the correct indication and to achieve an optimal result?] / Prothèse unicompartimentale du genou - Quels paramètres considérer pour poser la bonne indication et obtenir un résultat optimal ?

Unicompartmental knee arthroplasty (UKA) is considered an excellent alternative to total knee arthroplasty (TKA) in the treatment of unicompartmental femoro-tibial degeneration with superior functional scores, reduced morbidity and fewer complications. However, revision rates are higher, mainly during the early postoperative period. Failures are attributed to incorrect indications, surgical technical errors and to the low threshold to revision. Several clinical and radiological parameters have to be considered for a correct indication. A high surgical volume is mandatory to assure optimal outcome and survivorship.

La prothèse unicompartimentale du genou (PUC) est considérée comme une excellente alternative à la prothèse totale du genou (PTG) dans le traitement de l'arthrose monocompartimentale avec des scores fonctionnels supérieurs, une morbidité réduite et des taux de complications plus faibles. Cependant, les taux de révision sont plus élevés et se produisent principalement durant la période postopératoire précoce. Ils sont attribués à des indications incorrectes, à des erreurs chirurgicales et au fait que le seuil de révision est plus bas que pour une PTG. Plusieurs paramètres cliniques et radiologiques doivent être pris en considération afin de poser la bonne indication. Un volume chirurgical suffisant est nécessaire pour obtenir un résultat optimal et une survie prolongée de la PUC.

Total knee arthroplasty in achondroplasia without deformity correction: A case report with 11 years' follow-up.

Knee osteoarthritis in patients with achondroplasia is rare. Bowleg deformity is typical but corrective surgery is limited. Thus, primary total knee arthroplasty (TKA) might be challenging due to the particular anatomy. We report on a patient with 11 year's follow-up after a TKA performed maintaining bowleg alignment, using a posterior stabilized, fixed-bearing design. Sequential X-rays showed radiolucencies on the femoral component within two years postoperatively, slightly increasing over time but stable at last follow-up. The Oxford Knee Score showed an excellent result at 11 years. Despite the peculiarities of a case report, TKA without concomitant osteotomies might be an option for such patients. Nevertheless, a thorough discussion about pros and cons is paramount.

Perioperative Contamination of Orthopaedic Polyethylene Implants, Targeting Devices and Arthroscopes. Experts' Decision Tree and Literature Review.

Introduction Sterility errors during orthopaedic procedures can be stressful for the surgeon or scrub nurse and lead to devastating infectious complications and liability issues. This paper aims to review orthopaedic surgeon practices and propose possible attitudes to adopt. Methods Out of 1023 questionnaires sent, 170 orthopaedic surgeons answered a Volunteer Feedback Template (multiple-choice test) by SurveyMonkey® (San Mateo, CA, USA) anonymously. The survey questioned surgeon's response to a sterility mistake during a standard total knee joint replacement, trauma surgery and arthroscopic procedure. Those "sterility mistake" situations occurred when there was contamination of 1) a sterile polyethylene (PE) 2) a sterile targeting device, and 3) an arthroscope. Results When the definitive PE is contaminated, and if a new definitive PE will only be available 2 hours later, 52% of surgeons would wait for the new definitive PE (p<0.001). In the same situation, if a new PE will only be available in 4 hours, the results showed a significant difference favoring two other options: "putting a definitive PE one size smaller or bigger with balance adjustment" (31%); and "leaving the provisional PE in the joint, closing the wound and re-operating the patient in the coming days when the definitive PE arrives" (29%) (p<0.001). When the new PE is only available 24 hours later results were 34% and 31%, respectively (p<0.001). In the case of a surgical procedure for a classic intertrochanteric fracture, if the carbon fiber targeting device is contaminated, most surgeons (50%) chose to put the nail without the targeting device and finish the surgery (p<0.001). When the arthroscope is desterilized, 39% of participants would wait until the arthroscope has been sterilized again (approximately 2 hours), while 24% would use another procedure (p<0.001). Sixty-two percent of surgeons would adapt their strategy. No clear trend could be identified in terms of antibiotic treatment following a sterility error. Conclusions There are no established guidelines on how to deal with sterility breaches during surgery and on the antibiotic strategy following the prolonged surgical time resulting from the delay for a new implant. The most common course of action chosen by participating surgeons is detailed in our expert decision tree - if another sterile component is not available within 2 hours - : insertion of another PE size, rescheduling the operation, adapting the surgical technique (for trauma procedures), or soaking the arthroscope in disinfectant solution. As instances of contamination cannot be avoided, it is recommended to have a minimum of two copies of sterile PE implants, arthroscopes or targeting devices readily available before surgery begins-.

Population Variation and Genetic Control of Modular Chromatin Architecture in Humans.

Chromatin state variation at gene regulatory elements is abundant across individuals, yet we understand little about the genetic basis of this variability. Here, we profiled several histone modifications, the transcription factor (TF) PU.1, RNA polymerase II, and gene expression in lymphoblastoid cell lines from 47 whole-genome sequenced individuals. We observed that distinct cis-regulatory elements exhibit coordinated chromatin variation across individuals in the form of variable chromatin modules (VCMs) at sub-Mb scale. VCMs were associated with thousands of genes and preferentially cluster within chromosomal contact domains. We mapped strong proximal and weak, yet more ubiquitous, distal-acting chromatin quantitative trait loci (cQTL) that frequently explain this variation. cQTLs were associated with molecular activity at clusters of cis-regulatory elements and mapped preferentially within TF-bound regions. We propose that local, sequence-independent chromatin variation emerges as a result of genetic perturbations in cooperative interactions between cis-regulatory elements that are located within the same genomic domain.

Identification of the transcription factor ZEB1 as a central component of the adipogenic gene regulatory network.

Adipose tissue is a key determinant of whole body metabolism and energy homeostasis. Unraveling the regulatory mechanisms underlying adipogenesis is therefore highly relevant from a biomedical perspective. Our current understanding of fat cell differentiation is centered on the transcriptional cascades driven by the C/EBP protein family and the master regulator PPARγ. To elucidate further components of the adipogenic gene regulatory network, we performed a large-scale transcription factor (TF) screen overexpressing 734 TFs in mouse pre-adipocytes and probed their effect on differentiation. We identified 22 novel pro-adipogenic TFs and characterized the top ranking TF, ZEB1, as being essential for adipogenesis both in vitro and in vivo. Moreover, its expression levels correlate with fat cell differentiation potential in humans. Genomic profiling further revealed that this TF directly targets and controls the expression of most early and late adipogenic regulators, identifying ZEB1 as a central transcriptional component of fat cell differentiation.

Coordinated effects of sequence variation on DNA binding, chromatin structure, and transcription.

DNA sequence variation has been associated with quantitative changes in molecular phenotypes such as gene expression, but its impact on chromatin states is poorly characterized. To understand the interplay between chromatin and genetic control of gene regulation, we quantified allelic variability in transcription factor binding, histone modifications, and gene expression within humans. We found abundant allelic specificity in chromatin and extensive local, short-range, and long-range allelic coordination among the studied molecular phenotypes. We observed genetic influence on most of these phenotypes, with histone modifications exhibiting strong context-dependent behavior. Our results implicate transcription factors as primary mediators of sequence-specific regulation of gene expression programs, with histone modifications frequently reflecting the primary regulatory event.