Mineralogical assessment of the femoral heads and articular cartilage of the femur in patients with avascular necrosis (AVN)

The aim of this study was to analyze changes in the mineralization of the femoral head and articular cartilage of the femur in patients with primary avascular necrosis (AVN). The study included the femoral heads of nine patients with AVN, aged between 30 and 68 years. The surgical specimens of femoral heads were obtained during the procedure of hip replacement. The measurements of bone mineral density (DXA method) included in vivo examination of patients with AVN, conducted prior to the hip replacement procedure, as well as the densitometry of surgical specimens of the whole femoral heads and their 1.0-1.5 cm thick slices. The surgical specimens were also examined under digital, polarization, and scanning electron microscope, and analyzed chemically by means of electron dispersive spectroscopy (EDS). Moreover, the cartilage isolated from surgical specimens was subjected to X-ray diffractometry. Our study revealed that densitometry of the proximal femoral epiphysis is not useful in the evaluation of AVN. We observed that AVN is associated with severe osteoporosis of subchondral bone at a periphery of the femoral heads, leading to complete bone loss (“holes”) in extreme cases. Moreover, articular cartilage over the necrotic areas showed the signs of occult mineralization, resulting in its alterations and more rapid wear.