Notch strength insensitivity of self-setting hydroxyapatite bone cements.

The effect of notches on the strength properties of self-setting hydroxyapatite (HA) cements is examined. Such stress concentrators may be present at orthopedic repair sites employing cements and significantly affect their mechanical reliability. Notched tensile specimens were prepared from two cement compositions that resulted in HA and carbonated apatite. The notch radii was varied from 0.15 to 6 mm with a fixed length of 6 mm. The strength of the cements was found to be surprisingly insensitive to the presence of the notches over the range of notch radii examined. A fracture statistics model incorporating a Weibull statistical approach was employed to rationalize the observed notch insensitivity.