Biphasic creep and stress relaxation of articular cartilage in compression? Theory and experiments.
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Animals↗
Biomedical subjects
C G Armstrong
Publications and source records attributed to C G Armstrong.
In vitro measurement of articular cartilage deformations in the intact human hip joint under load.
Using a new roentgenographic technique for measuring cartilage deformation in intact joint specimens, twenty-eight normal human hip joints from subjects twenty-five to eighty-five years old were loaded with a force of five times body weight in a testing machine. The initial unloaded thickness of the articular cartilage of the femoral head and the changes in thickness of this cartilage under load were measured roentgenographically at seven to twelve sites on each femoral head. These measurements showed that the deformations of femiral-head articular cartilage under load in the intact joint are non-uniform and increase greatly with age. In twelve specimens measurements were also made of the increase in cartilage deformation with time when the load of five times body weight was maintained on the joint. A single osteoarthrotic joint was also studied. The experimental findings imply changes in the fundamental mechanical properties of the cartilage with age, which probably result from age-related alterations in cartilage microstructure and chemical composition.
Adult↗
Alteration with age in compliance of human femoral-head cartilage.
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Adult↗
Thickness and distribution of human femoral head articular cartilage. Changes with age.
The distribution of hyaline cartilage in the sagittal plane of the normal human femoral head was examined. 28 specimens from persons aged 10 to 68 years subject to post-mortem examination in a teaching hospital were anatomically orientated and x-rayed in a lateromedial projection. An optical technique was used to measure the cartilage thickness from the x-ray films thus produced. Measurements were made with a sensitivity of +/- 0-01 mm using a metrological projector. 11 defined sites on each femoral head were surveyed to give the distribution of cartilage thickness. The greatest thickness was identified anterior to the zenith. Between the ages of 20 and 45 years the thickness of this zone increased with age. The thickness of femoral head cartilage was not evidently related to femoral head diameter, femur length, or body weight.
Adolescent↗