Biomechanical Evaluation of the Accuracy in Radiographic Assessment of Femoral Component Migration Measurement after Total Hip Arthroplasty

Introduction: Implant subsidence is one criteria utilized to monitor for prosthesis loosening after total hip arthroplasty (THA) with initial implant subsidence assessment often done utilizing plain radiographs. The specific aim of this study was to identify the most reliable references when using plain radiographs to establish an image magnification with the goals being easy to use, inexpensive, reliable, and accurate. Methods: Two femoral stem implants (stem lengths: 127mm, 207mm) were utilized to simulate hemiarthroplasty of the hip with composite femurs. Different combinations of femoral stem distances from the radiographic film (ODD), source-detector differences (SDD), hip rotation, and hip flexion were elected. Standardized anterior-posterior pelvis for each parameter combination setup were taken. Radiographic measurements (head diameter, stem length, stem seating length) were undertaken five times by three examiners. Radiographic image magnification factors were generated from two references (head diameter and stem length). Radiograph measurement reproducibility and stem seating length errors using these magnification factors were evaluated. Results: High level of repeated measurements reliability was found for head diameter (99 ± 0%) and stem length (90 ± 7%) measurements, whereas seating length measurements were less reliable (76 ± 6%). Stem length error using the femoral head magnification factor yielded 11% accuracy. Stem seating length error using both magnification factors were not reliable (< 7% accuracy). All parameters, except SDD, showed significant effect on calibrated measurement error. Conclusions: Current methods of assessing implant subsidence after THA using plain radiographs are inaccurate or reliable. Clinicians should recognize these limitations and be cautious when diagnosing implant stability using plain radiographs alone

The plasticity of near space: evidence for contraction

The distinction between near space and the space farther away has been well established, as has the relation of this distinction to arm length. Recent studies provide evidence for the plasticity of near space, showing that it is possible to expand its extent ("size") through tool-use. In the present study, we examine the converse effect, whether contraction of near space results from increasing the effort involved on a line bisection task. Adult participants bisected lines at different distances, while, in some cases, wearing weights. In Experiment 1, the arms, specifically, were weighted (wrist weights), and in Experiment 2, more general body weights were used (heavy backpack). As in previous studies, unencumbered participants showed leftward bias when bisecting lines at the closest distances and a rightward shift in bias with increasingly farther distances. With wrist weights, but not a heavy backpack, participants showed more rightward bias at the closest distances, and a more gradual rightward shift with increasing distance, as if the nearest locations were represented as being farther away. These results suggest that increased effort, when specifically related to the arm, can serve to reduce the size of near space, providing support for the generally symmetrical plasticity of near space representations

Изготовление и исследование образцов из неметаллического материала для визуального контроля

В ходе практических экзаменов в рамках аттестации персонала в области неразрушающего контроля используются аттестационные образцы, содержащие один или несколько дефектов. В настоящее время существуют разные образцы для аттестации персонала, например стальные трубы, металлические пластины с дефектными сварными швами, но они выполнены из металлов, а т. к. аттестовать специалистов необходимо на образцах из материала, соответствующего действительному объекту контроля из перечня опасных производственных объектов, то предлагается вариант изготовления экзаменационного образца из неметаллического материала. Был разработан аттестационный образец из неметаллического материала для аттестации персонала в области неразрушающего контроля по визуальному и измерительному контролю.During the practical examinations in the framework of personnel certification in the field of nondestructive testing, attestation samples containing one or more defects are used. Currently, there are different samples for personnel certification, for example steel pipes, metal plates with defective welds, but they are made of metals, and since it is necessary to certify specialists on samples from the material corresponding to the actual object of control from the list of hazardous production objects, a variant of manufacturing an examination sample made of nonmetallic material. A certification sample was prepared from non-metallic material for the certification of personnel in the field of nondestructive testing by visual and measuring control

The Non-Unconscionability of Condominium Recreation Leases

The authors evaluate the theory of unconscionability as a basis for challenging long-term condominium recreation leases in Florida. They discuss the situation underlying such challenges and examine recent attempts to apply common law and U.C.C. unconscionability principles to recreation leases. An analysis of the realities of condominium development serves to dispel several commonly held misconceptions about recreation leases. The authors also analyze the presumption of unconscionability under the Florida Condominium Act, contrasting it with the proposed Federal Condominium Act. Recognizing the inefficacy of the unconscionability approach, the authors briefly discuss the recreation lease buy-out as a more feasible alternative solution