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Biomechanics and anthropology—A fruitful association
338
Abstracts
loading states. Using the entire loading range of an Instron materials testing machine, 150 pairs of canine radii were tested. One bone of each pair was subjected to either torsional or a combination of axial and torsional loads, and compared to a control specimen. Torque to failure and energy data was plotted versus loading rate. As loading rate increases, the torque and energy values were found to increase, reach a peak, and then decline at higher rates. The combined loading plots exhibit the same type of curve, only higher in magnitude, indicating an effect of axial loading. Fractures produced under this combined state of loading are representative of those clinically found in human trauma situations. BIOMECHANICS AND ANTHROPOLOGY-A
C. OWEN Lovuov
FRUITFUL ASSOCIATION
(Professor of Anatomy and Anthropology, Ohio 44242, U.S.A.)
Kent State University, Kent,
This paper will outline current data bases about normal human variation made available by modem physical anthropology and the techniques currently employed to interpret these data bases; will outline the generalcourse of human evolution during the past four million years as it relates to modern clinical problems in orthopaedic biomechanics; and will discuss relevant anatomical data from studies of other living and fossil primates. Particular foci will include the hip, knee, wrist, and ankle joints, which will be discussed both in terms of their structure and kinematics and the evolutionary history of these properties. By employing both comparative anatomy of extant primates and the human fossil record, specialized features of these joints peculiar to man and their biomechanical function can be more clearly understood. These data can provide a valuable background with which to approach biomechanical design and clinical practice. MECHANICS OF THE MEN&Cl
FREDERICKV~S~LJR~;H(Hospital for Special Surgery, New York, New York 10021, U.S.A.) A. JOHN BODINE(Beth Israel Hospital, Boston, MA, U.S.A.) In the knee, the menisci transmit a substantial portion of the compressive load passing between the femur and tibia. For this reason, the mechanical behavior of the menisci is of consequence to proper function and health in the knee. In the dog, the lateral meniscus has a significantly higher complex shear modulus, G*, than does the medial meniscus. For each, G* increases log-linearly with frequency of testing. However, the ratio of theviscous to elastic components of this stiffness increases only slightly. Because the men&i respond in time-dependent fashion, and with different moduli on the two sides, the distribution of stress that develops in the tibia1 cartilage should vary accordingly. CUMULATlVE
STRAIN IN TENDINOUS TISSUES IN RESPONSE TO PHYSIOLOGIC LOADS
S. A. GOLDSTEINand L. S. MATTHEWS(Section of Orthopaedic Surgery) T. J. ARMSTRONG and D. B. CHAFFIN(The Center for Ergonomics, The University of Michigan, Ann Arbor, MI, U.S.A.) Cumulative trauma disorders of the tendons and tendon sheaths in the hand and wrist have been associated with continuous repetitive tasks. This investigation was designed to examine the biomechanical aspects of tendon-tendon sheath articulations during physiologic usage patterns. Constitutive relationships, based on experimentally determined material properties of tendons in intact cadaver hands, were formulated. The results of the study indicate that an accumulation of strain does occur in tendinous tissues during physiologic loading. The results of the study also provide evidence that the accumulation of strain in collagenous tissues is an important etiological factor of chronic disorders of tendons and tendon sheaths. This study also supports the hypothesis that the tissues are strain limited.
MORPHOLOGY
OF COLLAGEN FIBERS IN INTESTINE AND ITS RELATlONSHlP TO MECHANICAL BEHAVIOR
J. W. ORRERC;,L. KLEIN and A. HILTNER(Case Western Reserve University, Cleveland, Ohio 44106, U.S.A.) Intestine is used commercially for its unusual tensile strength. Its mechanical behavior is related to the macrostructure of its collagen fibers. Fibers, about 14pm in diameter, biaxially oriented at + 30” and - 30” to the longitudinal direction, and a network of randomly oriented fibers, 0.2pm in diameter, were observed with optical polarizing and scanning electron microscopy. Initially the large fibers are crimped in undulating arrays which produces an extinction pattern in the optical microscope. Application of stress results in uncrimping of the large fibers, which is responsible for a “toe” region observed in load-elongation curves. The tissue is anisotropic
Abstracts
loading states. Using the entire loading range of an Instron materials testing machine, 150 pairs of canine radii were tested. One bone of each pair was subjected to either torsional or a combination of axial and torsional loads, and compared to a control specimen. Torque to failure and energy data was plotted versus loading rate. As loading rate increases, the torque and energy values were found to increase, reach a peak, and then decline at higher rates. The combined loading plots exhibit the same type of curve, only higher in magnitude, indicating an effect of axial loading. Fractures produced under this combined state of loading are representative of those clinically found in human trauma situations. BIOMECHANICS AND ANTHROPOLOGY-A
C. OWEN Lovuov
FRUITFUL ASSOCIATION
(Professor of Anatomy and Anthropology, Ohio 44242, U.S.A.)
Kent State University, Kent,
This paper will outline current data bases about normal human variation made available by modem physical anthropology and the techniques currently employed to interpret these data bases; will outline the generalcourse of human evolution during the past four million years as it relates to modern clinical problems in orthopaedic biomechanics; and will discuss relevant anatomical data from studies of other living and fossil primates. Particular foci will include the hip, knee, wrist, and ankle joints, which will be discussed both in terms of their structure and kinematics and the evolutionary history of these properties. By employing both comparative anatomy of extant primates and the human fossil record, specialized features of these joints peculiar to man and their biomechanical function can be more clearly understood. These data can provide a valuable background with which to approach biomechanical design and clinical practice. MECHANICS OF THE MEN&Cl
FREDERICKV~S~LJR~;H(Hospital for Special Surgery, New York, New York 10021, U.S.A.) A. JOHN BODINE(Beth Israel Hospital, Boston, MA, U.S.A.) In the knee, the menisci transmit a substantial portion of the compressive load passing between the femur and tibia. For this reason, the mechanical behavior of the menisci is of consequence to proper function and health in the knee. In the dog, the lateral meniscus has a significantly higher complex shear modulus, G*, than does the medial meniscus. For each, G* increases log-linearly with frequency of testing. However, the ratio of theviscous to elastic components of this stiffness increases only slightly. Because the men&i respond in time-dependent fashion, and with different moduli on the two sides, the distribution of stress that develops in the tibia1 cartilage should vary accordingly. CUMULATlVE
STRAIN IN TENDINOUS TISSUES IN RESPONSE TO PHYSIOLOGIC LOADS
S. A. GOLDSTEINand L. S. MATTHEWS(Section of Orthopaedic Surgery) T. J. ARMSTRONG and D. B. CHAFFIN(The Center for Ergonomics, The University of Michigan, Ann Arbor, MI, U.S.A.) Cumulative trauma disorders of the tendons and tendon sheaths in the hand and wrist have been associated with continuous repetitive tasks. This investigation was designed to examine the biomechanical aspects of tendon-tendon sheath articulations during physiologic usage patterns. Constitutive relationships, based on experimentally determined material properties of tendons in intact cadaver hands, were formulated. The results of the study indicate that an accumulation of strain does occur in tendinous tissues during physiologic loading. The results of the study also provide evidence that the accumulation of strain in collagenous tissues is an important etiological factor of chronic disorders of tendons and tendon sheaths. This study also supports the hypothesis that the tissues are strain limited.
MORPHOLOGY
OF COLLAGEN FIBERS IN INTESTINE AND ITS RELATlONSHlP TO MECHANICAL BEHAVIOR
J. W. ORRERC;,L. KLEIN and A. HILTNER(Case Western Reserve University, Cleveland, Ohio 44106, U.S.A.) Intestine is used commercially for its unusual tensile strength. Its mechanical behavior is related to the macrostructure of its collagen fibers. Fibers, about 14pm in diameter, biaxially oriented at + 30” and - 30” to the longitudinal direction, and a network of randomly oriented fibers, 0.2pm in diameter, were observed with optical polarizing and scanning electron microscopy. Initially the large fibers are crimped in undulating arrays which produces an extinction pattern in the optical microscope. Application of stress results in uncrimping of the large fibers, which is responsible for a “toe” region observed in load-elongation curves. The tissue is anisotropic