Mechanical Stress, Functional Adaptation and the Variation Structure of the Human Femur Diaphysis

ISBN-13: 9783540054641 / Angielski / Miękka / 1971 / 90 str.

E. Amtmann

Opis

According to the classical theory of functional structure of bone which was developed by J. Wolff (1884, 1892) and W. Roux (1895) following the investigations of the functional architecture of the substantia spongiosa by H. von Meyer (1867), bone is "functionally" laid down in gross form as well as in minute architecture in accordance with the "maximum-minimum-law". As a result of functional adaptation, a maximum of efficiency is achieved with a minimum of material (Kummer, 1962a). In this sense functional adaptation is a reaction of adaptation of the idiotype-within the bounds of the reaction norm-to a changed internal environment, that is in this case an adaptation to changed mechanical stresses. 1. The Formation of the Normal Femur Shape The heredity basis of shape characteristics of human femora is really unknown. Identical twins show a significant lower variability of length of femur than binovular twins. Population variability of length of femur due to heritability may exceed twice the variability due to environmental factors (Knussmann, 1968). A significant part of the total variation of femur shape characteristics remains therefore unexplained supposing that the sources of variation due to heritability and environmental factors are also nearly the same for the other traits.

Spis treści

A. Introduction.- 1. The Formation of the Normal Femur Shape.- 2. The Functional Structure of the Femur Corticalis.- 3. Forces Acting on Human Femur Cross-sections.- 4. The Aim of the Present Investigation.- B. Materials and Methods.- C. Results.- 1. The Variation in Density of the Femur Shaft.- a) Differences in Side of Body.- b) Height of Cross-section and Position of Bone Sample.- c) Age and Sex.- d) The Density Distribution of the Shaft.- e) Summary.- 2. The Variation of Breaking Strength in the Femur Shaft.- a) Differences in Side of Body.- b) Height of Cross-section and Position of Bone Sample.- c) Age and Sex, Height of Cross-section and Position of Bone Sample.- d) The Distribution of Breaking Strength across the Shaft.- e) Summary.- 3. The Variation of Structure Strength in the Shaft.- a) The Correlation between Density and Breaking Strength.- b) The Distribution of Structure Strength throughout the Shaft.- 4. Cross-sectional Area and Shape.- 5. Thickness of Compacta and Breaking Strength.- 6. Factor Analysis of the Variation Structure of Human Femur Cross-sections.- a) Introduction.- b) The Correlation Matrix, the Estimation of Communalities and the Number of Factors to be Determined.- c) Results.- D. Discussion.- 1. The Problem of Lack of Bone Resorption in the Vicinity of the Neutral Surface.- 2. The Adaptation of Femur Cross-sections to Fluctuating Bending Stresses on the Assumption that Bone is an Isotropic Material.- 3. The Adaptation of the Femur Compacta to Fluctuating Bending Stresses by Means of Specific Distribution of Anisotropic Bone Material.- 4. The Factors Affecting the Variation of Size, Shape, and Structure of the Femur Diaphysis.- Summary.- Zusammenfassung.- Subject-Index.