Antibacterial hydrogel coating in joint mega-prosthesis: results of a comparative series.

PURPOSE: Joint mega-prosthesis after bone tumors, severe trauma or infection is associated with high rates of post-surgical septic complications. A fast-resorbable antibacterial hydrogel coating (DAC®, Defensive Antibacterial Coating) has previously been shown to be able to significantly reduce surgical site infection in various clinical settings. Aim of the present study was to evaluate the safety and efficacy of the DAC hydrogel coating to prevent early periprosthetic joint infection after joint mega-prosthesis. METHODS: In this three-centers, case-control study, 43 patients, treated with an antibacterial hydrogel coated mega-prosthesis for oncological (N = 39) or non-oncological conditions (N = 4), were retrospectively compared with 43 matched controls, treated with mega-implants without the coating. Clinical, laboratory and radiographic examinations were performed to evaluate the occurrence of post-surgical infection, complications and adverse events. RESULTS: At a mean follow-up of 2 years, no evidence of infection or adverse events were observed in the DAC-treated group, compared to six cases of post-surgical infection in the control group. CONCLUSION: This matched case-control study shows that a fast-resorbable, antibiotic-loaded coating can be safely used to protect joint mega-prosthesis, providing a reduction of early surgical site infections with no side effects. Larger prospective trials with longer follow-ups are warranted to confirm this report. TRIAL REGISTRATION: RS1229/19 (Regina Elena National Cancer Institute Experimental Registry Number).

Non-unions.

Non-union of long bones is a significant consequence of fracture treatment. Bone regeneration is a complex physiological process of bone formation which can be seen during normal fracture healing. An improved understanding of the molecular and cellular events that occur during bone repair and remodelling has led to the development of biologic agents that can augment the biological microenvironment and enhance bone repair. Currently, there are different strategies to augment the impaired or "insufficient" bone-regeneration process, including the "gold standard" autologous bone graft, free fibula vascularised graft, allograft implantation, and use of growth factors, osteoconductive scaffolds, osteoprogenitor cells and distraction osteogenesis. A lack of standardized outcome measures for comparison of biologic agents in clinical fracture repair trials, frequent off-label use and a limited understanding of the biological activity of these agents at the bone repair site have limited their efficacy in clinical applications.

Atypical lipomatous tumors: should they be treated like other sarcoma or not? Surgical consideration from a bi-institutional experience.

BACKGROUND: To identify the best surgical approach to atypical lipomatous tumors we reviewed 171 patients who underwent surgery at two sarcoma referral centers with different surgical policies. METHODS: Of the 151 patients (88 %) with primary tumors, 95 were treated at Institution A and 76 were treated at Institution B. At Institution A, a wide surgical resection, including a slight cuff of soft tissue around the mass, was adopted, which was defined as marginal resection (MR) according to the Enneking classification. At Institution B, a simple tumor resection (SR), according to the Enneking classification, was employed. En bloc surgical resection was the goal in both centers. The primary outcomes of the study were local recurrence-free survival (LRFS), incidence of secondary dedifferentiation at recurrence, and presence of residual tumor after re-excision. RESULTS: Sixteen patients (9 %) had local recurrence. The 10-year LRFS was 82 %. No cases of secondary dedifferentiation were observed. Residual tumor after re-excision was found in 46 % of cases. In univariate analysis, sclerosing subtype, tumor rupture, and SR were unfavorable prognostic factors for LRFS. Sclerosing subtype and tumor rupture were independent prognostic factors for LRFS in multivariate analysis. SR was significantly associated with tumor rupture. CONCLUSIONS: Sclerosing subtype and tumor rupture are unfavorable prognostic factors for local recurrence. MR is associated with a lower risk of tumor rupture than SR. Neurovascular and major muscle resections are not necessary in principle. Re-excision after unplanned surgery is not always mandatory. A preoperative core needle biopsy could be useful in identifying the sclerosing subtype.

Dynamics of cooperative excavation in ant and robot collectives.

The solution of complex problems by the collective action of simple agents in both biologically evolved and synthetically engineered systems involves cooperative action. Understanding the resulting emergent solutions requires integrating across the organismal behavior of many individuals. Here, we investigate an ecologically relevant collective task in black carpenter ants Camponotus pennsylvanicus: excavation of a soft, erodible confining corral. These ants show a transition from individual exploratory excavation at random locations to spatially localized collective exploitative excavation and escape from the corral. Agent-based simulations and a minimal continuum theory that coarse-grains over individual actions and considers their integrated influence on the environment leads to the emergence of an effective phase space of behaviors, characterized in terms of excavation strength and cooperation intensity. To test the theory over the range of both observed and predicted behaviors, we use custom-built robots (RAnts) that respond to stimuli to characterize the phase space of emergence (and failure) of cooperative excavation. Tuning the amount of cooperation between RAnts, allows us to vary the efficiency of excavation and synthetically generate the entire range of macroscopic phases predicted by our theory. Overall, our approach shows how the cooperative completion of tasks can arise from simple rules that involve the interaction of agents with a dynamically changing environment that serves as both an enabler and a modulator of behavior.

Simulating the evolution of bipedalism and the absence of static bipedal hexapods.

In nature, very few animals locomote on two legs. Static bipedalism can be found in four limbed and five limbed animals like dogs, cats, birds, monkeys and kangaroos, but it cannot be seen in hexapods or other multi-limbed animals. In this paper, we present a simulation with a novel perspective on the evolution of static bipedalism, with a virtual creature evolving its body and controllers, and we apply an evolutionary algorithm to explore the locomotion transition from octapods to bipods. We find that the presence of four limbs in the evolutionary trajectory of the creature scaffolds a parametric jump that enables bipedalism, and shows that hexapods, without undergoing such transformation, struggle to evolve into bipeds. An analysis of the transitional parameters points to the role of a shorter femur length in helping maintain the stability of the body, and the tibia length is responsible for improving the forward speed.

Reachability Improvement of a Climbing Robot Based on Large Deformations Induced by Tri-Tube Soft Actuators.

Locomotion of soft-bodied organisms, such as amoeba, worms, and octopuses, is safe, robust, and adaptable and has great promise for applications in complex environments. While such organisms fully exploit the potential provided by their soft structures, engineering solutions commonly constrain soft deformation in favor of controllability. In this study, we study how soft deformations can enhance the climbing capabilities of a robot. We introduce a robot called Longitudinally Extensible Continuum-robot inspired by Hirudinea (LEeCH), which has few shape constraints. Inspired by real leeches, LEeCH has a flexible extensible body and two suction cups at the ends. It is capable of performing 3D climbing locomotion using two suction cups driven by vacuum pumps and tri-tube soft actuators which have only three DC motors. The large deformations occurring in LEeCH extend its workspace compared to robots based on constant curvature models, and we show successful locomotion transition from one surface to another at angles between 0° and 180° in experiment. We develop a model based on multibody dynamics to predict the nonlinear deformations of the robot, which we verify in the experiment. The model reveals a nondimensional morphological parameter, which relates the robot's shape to its mass, stiffness, and size. The workspace of LEeCH as a function of this parameter is studied in simulation and is shown to move beyond that of robots based on constant curvature models.

Physics driven behavioural clustering of free-falling paper shapes.

Many complex physical systems exhibit a rich variety of discrete behavioural modes. Often, the system complexity limits the applicability of standard modelling tools. Hence, understanding the underlying physics of different behaviours and distinguishing between them is challenging. Although traditional machine learning techniques could predict and classify behaviour well, typically they do not provide any meaningful insight into the underlying physics of the system. In this paper we present a novel method for extracting physically meaningful clusters of discrete behaviour from limited experimental observations. This method obtains a set of physically plausible functions that both facilitate behavioural clustering and aid in system understanding. We demonstrate the approach on the V-shaped falling paper system, a new falling paper type system that exhibits four distinct behavioural modes depending on a few morphological parameters. Using just 49 experimental observations, the method discovered a set of candidate functions that distinguish behaviours with an error of 2.04%, while also aiding insight into the physical phenomena driving each behaviour.

Collision-based energetic comparison of rolling and hopping over obstacles.

Locomotion of machines and robots operating in rough terrain is strongly influenced by the mechanics of the ground-machine interactions. A rolling wheel in terrain with obstacles is subject to collisional energy losses, which is governed by mechanics comparable to hopping or walking locomotion. Here we investigate the energetic cost associated with overcoming an obstacle for rolling and hopping locomotion, using a simple mechanics model. The model considers collision-based interactions with the ground and the obstacle, without frictional losses, and we quantify, analyse, and compare the sources of energetic costs for three locomotion strategies. Our results show that the energetic advantages of the locomotion strategies are uniquely defined given the moment of inertia and the Froude number associated with the system. We find that hopping outperforms rolling at larger Froude numbers and vice versa. The analysis is further extended for a comparative study with animals. By applying size and inertial properties through an allometric scaling law of hopping and trotting animals to our models, we found that the conditions at which hopping becomes energetically advantageous to rolling roughly corresponds to animals' preferred gait transition speeds. The energetic collision losses as predicted by the model are largely verified experimentally.

Identification of a new nonsense mutation (Tyr129Stop) of the SRY gene in a newborn infant with XY sex-reversal.

Point mutations and deletions of SRY gene have been described in several cases of XY gonadal dysgenesis. To date, most of these mutations affect the HMG domain of SRY which plays a central role in DNA binding activity of SRY. We report on a non-mosaic XY sex-reversed newborn girl (completely female external genitalia). The direct sequencing of SRY showed a new nonsense mutation in a codon of SRY gene flanking the 3' end of the HMG domain: a thymine is replaced by a guanine at position +387 in codon 129, resulting in the replacement of the amino acid tyrosine (TAT) by a stop codon (TAG). The new mutation of this patient provides further evidence to support the functional importance of the putative DNA binding activity of the HMG-box domain.