Characterization of the effect of microfracture surgery and angle of incidence on the structural properties of femoral bone

Abstract

Microfracture surgery is one of the most common treatment options for knee osteoarthritis, a chronic inflammatory disease of the knee joint. However, a recent study by Theodoropoulos et al. (2012) has shown that there are significant variations in the angle of surgical awl used by surgeons in microfracture surgery as well as in the rehabiliation regimen prescribed following surgery. The purpose of this experiment was to characterize the structural properties of femoral bone before and after microfracture, with varying awl angles of impact. Microfracture at three different awl angles of impact, each between 0 and 30 degrees, was conducted on bone cubes cut from femoral condyles. Uniaxial compressive testing was conducted pre- and post- microfracture to determine changes in the stiffness of the bone. The results from this study show that there are significant decreases in the stiffness of femoral bone following microfracture surgery. However, different awl angles do not seem to result in significant decreases in bone stiffness. In addition, these results suggest that at the relatively low awl angles that were tested, differences in the angle of surgical awl used do not significantly affect the structural integrity of knee bone. Uniaxial testing appears a useful tool for characterizing the structural properties of bone, and further animal studies on the stiffness of bone at different timepoints following microfracture surgery could assist physicians in prescribing more suitable rehabilitation regimens. Keywords: knee osteoarthritis; microfracture; biomechanical testing; femoral condyle; awl angle; bone stiffness