Early post-operative walking bouts are associated with improved gait speed and symmetry at 90 days.

INTRODUCTION: There is a paucity of literature on optimal patterns of daily walking following joint arthroplasty, which are now evaluated with consumer technologies like smartphones, and can enhance our understanding of post-operative mobility. When smartphone-recorded, daily walking patterns are captured, qualities of gait-recovery such as gait speed or symmetry can be analyzed in real-world environments. RESEARCH QUESTION: Are the daily distribution of walking bouts in the early post-operative period associated with 90-day gait quality measures following hip and knee arthroplasty? METHODS: Gait data was collected passively using a smartphone-based care management platform in patients undergoing hip and knee arthroplasty. As recorded via subjects' free-living smartphone-collected gait bouts, data were investigated as a function of the walking session length and were used to create a ratio to the total time logging bouts, representing the fraction of walking performed during a single session per day (aggregation score). Quantile regression was performed to evaluate the association between early walking session lengths or aggregation score at 30 days post-operatively and the gait-sampled speed and asymmetry of walking at 90 days. RESULTS: In total, 2255 patients provided evaluable data. The walking session length at 30 days was positively associated with 90-day mean gait speed across procedure types where quantile regression coefficients ranged from 0.11 to 0.17. In contrast, aggregation score was negatively associated with gait speed at 90 days, with coefficients ranging from -0.18 to -0.12. SIGNIFICANCE: The duration and frequency of walking bouts was associated with recovery of gait speed and symmetry following lower limb arthroplasty. The findings may help clinicians design walking protocols that are associated with improved gait metrics at 3 months.

Utilidad de la conformación del túnel liso antes de usar limas rotatorias endodónticas de níquel-titanio / Usefulness of shaping the glide path before using rotary nickel-titanium endodontic files

Introducción: para prevenir la fractura de instrumentos endodonticos actualmente se siguen investigando materiales, técnicas y diseños los cuales buscan reducir su incidencia. La conformación de túnel liso (Glide Path) se ha propuesto con este fin, sin embargo su utilidad ha sido controvertida. Objetivo: comprobar teóricamente mediante la utilización de un análisis de elementos finitos, la utilidad de la conformación de túnel liso, antes de la utilización de limas rotatorias endodonticas de níquel-titanio. Métodos: se realizó una simulación numérica mediante un análisis de elementos finitos, para lo cual se construyeron modelos matemáticos de las limas rotatorias de níquel-titanio S1 y S2 de la serie Protaper®. Con el software Simulation multyphisics de Autodesk® se programaron las propiedades mecánicas de las limas y un límite de falla por fractura de 1270,588 MPa. Posteriormente se aplicó el torque recomendado por el fabricante y se fijo la punta del instrumento (sin conformación de túnel liso) aplicando allí restricciones en todos los grados de libertad.Para simular la realización de la conformación de túnel liso, se aplicaron restricciones en todos los grados de libertad a una determinada distancia de la punta del instrumento, simulando de esta forma que la punta del instrumento permanecía libre. Resultados: al fijar la punta de las limas, los esfuerzos máximos fueron 1545,77 MPa para la S1 y 1306,47 MPa para la S2, observando fractura de los instrumentos. Al fijar las limas a distancia de la punta no se observó fractura. Conclusiones: se demostró teóricamente que al impedir que se atrapen la punta de las limas, se previene su fractura y que dicho atrapamiento se evita con una conformación de túnel liso, por lo que se concluye que este procedimiento es útil para prevenir la fractura de los instrumentos rotatorios de níquel-titanio(AU)

Introduction: materials, techniques and designs continue to be studied with the purpose of reducing the incidence of fracture in endodontic instruments. Shaping of the glide path has been proposed for this end; however, its usefulness has been a matter of controversy. Objective: based on the finite element method, carry out a theoretical analysis of the usefulness of shaping the glide path before using rotary nickel-titanium endodontic files. Methods: numerical simulation was performed based on finite element analysis, to achieve which mathematical models were built of rotary nickel-titanium files S1 and S2 of the Protaper™ series. Autodesk™ Simulation Multiphysics software was used to program the mechanical properties of the files, as well as a fracture failure limit of 1270.588 MPa. The torque recommended by the manufacturer was then applied and the instrument tip fixed into place (without shaping the glide path) with restrictions on all degrees of freedom. In order to simulate glide path shaping, restrictions were applied to all degrees of freedom at a certain distance from the instrument tip, thus simulating that the instrument tip remained free. Results: on fixing the file tips, maximum efforts were 1545.77 Mpa for S1 and 1306.47 Mpa for S2. Instrument fracture was observed. When files were fixed at a distance from the tip, no fracture was observed. Conclusions: it was theoretically demonstrated that when file tips are prevented from being caught, fracture is prevented as well, and such catch is avoided by shaping the glide path. It is therefore concluded that the procedure is useful to prevent the fracture of rotary nickel-titanium instruments(AU)