Residual Stresses in Bone as Determined by a Slotting Method

To date, residual stresses in bone have been investigated primarily by X-ray diffraction. In recent years, the slitting method has become well-established for determining residual stresses in engineering materials. This study develops and applies a version of slitting using a small slot to find residual stresses vs. depth in layers near the surface of bovine femurs. Results are obtained at three locations around the circumference of the central region (diaphysis) of hydrated femurs from both mature and young cows. The magnitude of residual stresses was found to be greatest in thin layers near the surface, typically 100 to 200 μm deep. Residual stresses near the surface in mature femurs were compressive at two circumferential locations, and tensile at a third. In hydrated young femurs, residual stresses near the surface were tensile or minimal at similar locations. Large tensile residual stresses were found in experiments with intentionally air dried mature femurs.