HKA Angle—A Reliable Planning Parameter for High Tibial Osteotomy: A Theoretical Analysis Using Standing Whole-Leg Radiographs

High tibial osteotomy (HTO) is a recognized treatment for early-stage medial compartment knee osteoarthritis. Preoperative planning with standing whole-leg radiographs (WLRs) is essential for ensuring optimal postoperative alignment. The primary purpose of this study is to investigate the theoretical accuracy of the wedge opening required for two different preoperative planning parameters in open-wedge HTO. The second purpose is to theoretically determine which parameter is superior. Preoperative planning for HTO was performed with standing WLRs for 39 knees with isolated medial osteoarthritis. The Miniaci preoperative planning method was applied to correct the hip-knee-ankle (HKA) angle to 3to 6 degrees of valgus and the weight-bearing line (WBL) percentage within 60 to 70% of the width of the tibial plateau. To ensure that the HKA angle was between 3 and 6 degrees of valgus, the required accuracy window for the Miniaci angle was 3.25 ± 0.03 degrees (range, 3.20–3.30°). To ensure that the WBL percentage was between 60 and 70%, the accuracy window required for the Miniaci angle was 2.35 ± 0.13 degrees (range, 2.10–2.65°). This study suggests that to correct the HKA angle and the WBL percentage within the target range on two-dimensional WLRs, the Miniaci angle must be controlled to an accuracy of ± 1.63 and ± 1.18 degrees, respectively. Theoretically, the HKA angle is highly suitable as a preoperative planning parameter for HTO with a large permissible error and a small variability in the degree of change in the Miniaci angle (ΔMiniaci).

DIN 18041:2016 – Eine Norm im raumakustischen „Abseits“?/DIN 18041:2016 – A norm in room acoustic offside?

Die Neufassung der wichtigsten deutschen Norm zur Raumakustik vor 3 Jahren hat zwar den bewerteten Absorptionsgrad aw als untauglichen Einzahlparameter für die Planung eliminiert. Dafür wurde aber der empfohlene Toleranzbereich für die maximal zulässige Nachhallzeit bei Frequenzen unter 250 Hz stark erweitert. Diese und einige andere Änderungen werden einer kritischen Betrachtung hinsichtlich Sprachverstehen und Schallbelastung unterzogen und Berater vor einer unkritischen Anwendung der DIN 18041 in der aktuellen Version gewarnt.   Summary A revision 3 years ago of the most relevant German room acoustics standard has eliminated the inadequate weighted absorption coefficient aw as a planning parameter. In its place, however, the recommended tolerance for the maximum allowed reverberation time below 250 Hz was heavily extended. These and a few other peculiarities are critically reviewed with respect to speech intelligibility and noise generation in communication rooms and consultants warned of an uncritical application of DIN 18041 in its present reading.

A Constructive Approach to the Evolution of the Planning Ability

Human beings have behavioral flexibility based on a general faculty of planning for future events. This paper describes the first stage of a study on the evolution of planning abilities. A blocks world problem is used as a task to be solved by the agents, and encode an inherent planning parameter into the genome. The result of computer simulation shows a general tendency that planning ability emerges when the problem is difficult to solve. When taking social relationships, especially in the collective situation, into account, planning ability is difficult to evolve in the case that the problem is complex because there is a conflict between personal and collective interests. Also, the simulation results indicate that sharing information facilitates evolution of the planning ability although the free rider problem tends to be more serious than the situation where agents do not share information. It implies that there is a strong connection between evolution of the planning ability and symbolic communication.

A Constructive Approach to the Evolution of the Planning Ability

Human beings have behavioral flexibility based on a general faculty of planning for future events. This paper describes the first stage of a study on the evolution of planning abilities. A blocks world problem is used as a task to be solved by the agents, and encode an inherent planning parameter into the genome. The result of computer simulation shows a general tendency that planning ability emerges when the problem is difficult to solve. When taking social relationships, especially in the collective situation, into account, planning ability is difficult to evolve in the case that the problem is complex because there is a conflict between personal and collective interests. Also, the simulation results indicate that sharing information facilitates evolution of the planning ability although the free rider problem tends to be more serious than the situation where agents do not share information. It implies that there is a strong connection between evolution of the planning ability and symbolic communication.