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.