Foot Deformity Correction with Hexapod External Fixator, the Ortho-SUV Frame™

External fixators enable distraction osteogenesis and gradual foot deformity corrections. Hexapod fixators have become more popular than the Ilizarov apparatus. The Ortho-SUV Frame™ (OSF; Ortho-SUV Ltd, St. Petersburg, Russia), a hexapod that was developed in 2006, allows flexible joint attachment such that multiple assemblies are available. We assessed the reduction capability of several assemblies. An artificial bone model with a 270-mm-long longitudinal foot was used. A 130-mm tibial full ring was attached 60 mm proximal to the ankle joint. A 140-mm, two-third ring forefoot was attached perpendicular to the metatarsal bone axis. A 130-mm, two-third ring hindfoot was attached parallel to the tibial ring. A V-osteotomy, which was combined with 2 oblique osteotomies at the navicular-cuboid bone and the calcaneus, was performed. The middle part of the foot, including the talus, was connected to the tibial ring. We assessed 5 types of forefoot applications and 4 types of hindfoot applications. The range of correction included flexion/extension in the sagittal plane, adduction/abduction in the horizontal plane, and pronation/supination in the coronal plane. Additionally, we reported the short-term results in 9 clinical cases. The forefoot applications in which the axis of the hexapod was parallel to the axis of the metatarsal bones had good results, with 52°/76° for flexion/extension, 48°/53° for adduction/abduction, and 43°/51° for pronation/supination. The hindfoot applications in which the hexapod encircled the ankle joint also had good results, with corresponding values of 47°/58°, 20°/35°, and 28°/31°. Clinically, all deformities were corrected as planned. Thus, multiple assemblies and a wide range of corrections are available with the OSF. © 2013 American College of Foot and Ankle Surgeons

Introducing Assignment Functions to Bayesian Optimization Algorithms

In this paper we improve Bayesian optimization algorithms by introducing proportionate and rank-based assignment functions. A Bayesian optimization algorithm builds a Bayesian network from a selected sub-population of promising solutions, and this probabilistic model is employed to generate the offspring of the next generation. Our method assigns each solution a relative significance based on its fitness, and this information is used in building the Bayesian network model. These assignment functions can improve the quality of the model without performing an explicit selection on the population. Numerical experiments demonstrate the effectiveness of this method compared to a conventional BOA. Key words: evolutionary computation, Bayesian optimization algorithms, assignment functions

Spring technique for correction of multilevel deformity using hexapod external fixator

Context: Osteotomies in several parts of one long bone are recommended for correction of a long, curved, and wide-angled deformity. Hexapod external fixators (HEFs) allow for the single-stage correction of multiplanar deformity, but they are heavy, expensive, and requires continuous management of 12 struts, if at more than one level. Aims: We proposed the use of springs with HEF to support the intermediate ring. Deformity between the proximal and distal rings is corrected using one HEF, and the intermediate fragment is automatically corrected by the tension of the springs. Settings and Design: This was a retrospective descriptive study. Subjects and Methods: We treated seven males and eight females with 17 affected limbs. Four patients with familial hypophosphatemic rickets, five posttraumatic deformities, two osteogenesis imperfectas, three fibrous dysplasias, and one neurofibromatosis were included. The mean preoperative angle between the most proximal and distal fragments was 62.5°. First, small distraction at each level was initiated with one HEF fixed to the most proximal and distal rings, and Ilizarov hinges applied between the proximal and intermediate rings. Then, a set of three springs was applied for each interval between the rings. Gradual correction using HEF was performed, considering only the axes of the proximal and distal bone fragments. Results: Good alignment was achieved in all patients without severe complications. The mean correction period was 5.5 weeks and mean fixation period was 33.8 weeks. Conclusion: Combination of HEF and springs is capable of correcting severe deformity

Exploiting diversity in an asynchronous migration model for distributed differential evolution

In this paper an improved version of a general-purpose asynchronous adaptive multi-population model for distributed Differential Evolution algorithm is investigated. Specifically, in addition to an asynchronous mechanism for a multi-population recombination employed to exchange information, the distributed algorithm is endowed also with an innovative mechanism able to exploit diversity for the selection of the subpopulations involved in the asynchronous communication. Moreover the model is provided with a specific updating scheme to randomly update the control parameter values. The asynchronous migration mechanism and the adaptive procedure allow reducing the number of control parameters to be set and tuned in the distributed model respectively. The proposed distributed algorithm has been tested on the benchmarks of the CEC2016 real parameter single objective competition without adopting any specific mechanism opportunely tailored for solving such test problems. The results compared with the basic version of the distributed algorithm reveal an improvement in the performance in most of the considered benchmarks