A Feasibility Study for Usefulness of Preoperative Simulation of Medial Open-wedge High Tibial Osteotomy for Predicting Postoperative Realignment

Three-dimensional preoperative surgical realignment simulation of medial open-wedge high tibial osteotomy (OWHTO), in which simplified as the rigid rotation around the hinge axis, has been performed to predict the postoperative change and to develop a patient specific instrument for accurate osteotomy. However, the realistic practicality of this extremely simplified simulation method has not been verified. The purpose of this study was to investigate the usefulness of realignment simulation, in which medial OWHTO is simplified as a rotation around a hinge axis, in comparison with a postoperative CT model. Three-dimensional surface model of the tibia and femur was created from preoperative computed-tomography (CT) images (preoperative model) of three patients. Sixty computer simulation models of the medial OWHTO in each patient were created by realignment simulation, in which medial OWHTO is simplified as the rigid rotation of proximal part of tibia relative to the distal part from 1 degree to 20 degrees around three type of hinge axes. The simulation models were compared with the actual postoperative model created from postoperative CT images to assess the reality of the simulation model. After the distal parts of the tibia between each simulation model and postoperative CT model were aligned by a surface registration, average surface distance between two models was calculated as an index representing the similarity of the simulation model to the postoperative model. The minimum average surface distance between the simulation and postoperative CT models were almost 1mm in each patient. The rotation angles at which the minimum average surface distance was represented were almost identical to the actual correction angles. Overlaying the simulation and the postoperative CT models, we found that the posterior tibial tilt and the axial rotation of the proximal tibia of the simulation model well represented that of the postoperative CT model as well as the valgus correction. Therefore, the realignment simulation of medial OWHTO simplified as the rigid rotation around the hinge axis can generate the realistic candidates of postoperative realignment that includes the actual postoperative realignment, suggesting the usefulness for the preoperative simulation method.

Estudo do movimento de Bennett

Forty patients, twenty female and twenty male were selected, from a individual group. All the selected patients had twenty six teeth or more. lndividual alginate impressions were takenin the upper and lower arches. After each individual impression had taken, an índividual hinge axis procedure was effectived with a kinematic face bow. Determined the hínge axis each patient was tatued and a arbitrary face - bow was used to mount the upper cast in the gnathothesíometer. The lower cast was related to upper cast throught a centric relation registration (individual). Mounted both casts (upper and lower) in the instrument, two laterals bite registration were taken (one rigth, one left) on the patient and transfered to the gnatho-thesíometer for measurements. The results showed that Bennett moviment, occurred in 1,5 mm average and thus was related to an intimate occlusal scheme for each patient.

Determinação do eixo intercondilar

This study is for the arbitrary intercondilar to the real intercondilar hinge axis, with the help of a kinematic face bow. In the 21 patients we determined the real and the arbitrary hinge axis, registering the results in a melimetred paper. The results obtained were compared confirming that 58% the real intercondilar hinge axis was localized into a radius of 4 mm from the arbitrary intercondilar hinge axis.

Human Temporomandibular Joint Motion: A Synthesis Approach for Designing a Six-Bar Kinematic Simulator

The human earcanal can accommodate several types of in-ear devices including hearing aids, earphones, hearing protectors and earplugs. This canal-type home has a neighbor called the Temporomandibular Joint (TMJ) whose movements slightly deform the shape of the earcanal. While these cyclic deformations can influence the positioning, comfort and functioning of ear-fitted devices, they can also provide a significant amount of energy to harvest. Given their importance, the TMJ movements and earcanal deformations have been well studied. However, their mutual actions are still not fully understood. This paper presents the development of a six-bar kinematic TMJ simulator capable of replicating the complicated motion of the jaw. The development relies on a two-phase mechanism design algorithm to numerically optimize and analytically synthesize linkage mechanisms for which the classical optimization approaches cannot return a converged solution. The proposed algorithm enables the design of a kinematic simulator to generate the TMJ path with an average error as low as 1.65 % while respecting all the hinge-axis parameters of the jaw. This algorithm can be subsequently used to solve nonlinear complex linkage synthesis problems and ultimately, the developed kinematic simulator can be used to further investigate TMJ-earcanal interactions.

Computer Program for Digital Data Analysis of Facebow Records – Part І

The purpose of the study is to create computer program for the achievement of precise digital data processing of records performed with the “Facebow Mini-Maxi” and the facilitation of information transfer to the articulator.Material and method: A conceptual project was developed in order to create a new software product and requirements were defined towards its capacities, which are to provide guidance for its creation. With the assistance of computer programmer, the project was implemented.Results: The computer program “Facebow Mini-Maxi Analyzer” for digital data processing of registrants performed with the auricular type facebow was created. The program provides automatic recognition, reading, calibration and measurement of data obtained by “Facebow Mini-Maxi”. The main module gives us opportunities for measuring the values of: the sagittal condylar pathway; the arrow point angle and the length of the hinge axis. After finalizing the calculations, the software automatically generates a scheme with visualization of the parameters that significantly supports the dental technician when it comes to defining the accurate position of the models in dental articulator with individual parameters.Conclusion: The computer program provides accurate analysis of facebow records and assists in determining individual patient movement parameters of the lower jaw. The obtained results from the analysis improve the precision of casts mounting in articulator. The program cuts down the risk of subjective error when analysing the data via manual measurement of the recorded parameters on paper carrier.

A linear guide-based actuation concept for a novel morphing aileron

ABSTRACTThis paper deals with the actuation system design of a full-scale morphing aileron for regional aircraft. The aileron is allowed to smoothly change its geometrical configuration and perform the in-flight transition from a baseline shape to a set of optimal morphed ones pre-defined on the basis of aerodynamic requirements. The design of such innovative aileron is aimed not only at substituting the conventional aileron installed on a real aircraft but also to provide additional functionality. The aileron is free to rotate around its main hinge axis and it is also allowed to smoothly modify camber with two independent actuation systems. In such manner it can be used also during cruise with a symmetric deflection between the two half wings in order to reduce drag in off design condition. To accomplish variable aileron shape, a rigid-body mechanism was designed. The proposed aileron architecture is characterised by segmented adaptive ribs rigidly linked each other with spanwise reinforcements such as spars and stringers in a multi-box arrangement. Each rib is split into two movable plates connected by means of rotational hinges in a finger-like mechanism. The mechanism is driven by a load-bearing actuator by means of a kinematic chain opportunely tied based on the structural requirements in terms of shape to be matched and load to be withstood. The proposed device is an innovative arrangement of the quick-return mechanism composed of a beam leverage, commercial linear guides and a crank. The actuator shaft is directly inserted in the crank, which transmits the rotation to the linear guide that slide along a rail moving upward or downward the beam thus resulting in a camber variation. The entire aileron is moved by three leverages internally contained and distributed along the first two bays while the most external ribs are considered passive and their movement slaved. Two actuation layouts are analytically and numerically studied, the analytical theory is presented and validated by means of a multi-body simulation. Moreover, a linear static analysis was carried out under the hypothesis of glued contact between linear guides components simulating a jamming condition. This assumption has been formulated because it represents the most severe condition that envelop all the operative loads to which the actuation system is subjected. The analyses conducted are preliminarily aimed to verify that no failure occur under the imposed loads. In this first design loop, the vertical static force acting on the linear carriage exceeded allowable value and then a new configuration with double-sided linear guides was then investigated.