Topology of microfractures in osteonecrotic femoral heads at μCT and histology

• Published in: Bone (New York, N.Y.) N.Y.), 2020-12, Vol.141, p.115623-115623, Article 115623
• Main Authors: Mourad, Charbel, Galant, Christine, Wacheul, Emilie, Kirchgesner, Thomas, Michoux, Nicolas, Vande Berg, Bruno
• Format: Article
• Language: English
• Subjects: Epiphyseal collapse; Histology; Microfracture; Osteonecrosis; μCT
• ISSN: 8756-3282; 1873-2763
• DOI: 10.1016/j.bone.2020.115623

To assess the topology of bone and cartilage microfractures in osteonecrotic femoral heads. Sixteen resected human femoral heads with collapsed osteonecrosis (ON, n = 11) or osteoarthritis (OA, n = 5) were imaged at μCT with 12 μ nominal resolution. Forty-seven histological sections and μCT reformats with (n = 30) or without (8 from ON and 9 from OA femoral heads) osteonecrotic lesions were obtained and divided in 2 × 2 mm segments by a superposed grid. A radiologist and a pathologist separately assessed the presence of bone and cartilage microfractures in each segment on μCT and histological images, respectively. We determined the frequency and distribution of segments with bone microfractures according to a zonal distribution. Matrix analysis was performed by using Matlab to calculate the connectivity index and long/short axis ratios of clustered segments with microfractures. Segments with bone microfractures but not with cartilage microfractures were found more frequently in ON than in OA femoral heads. In the 38 matched μCT and histological images from ON femoral heads, 86%/82% of segments with cortical microfracture, 91%/96% of segments with trabecular microfractures involved ON lesions at μCT/histology. At histology, 83% of segments with cartilage microfractures involved ON lesions. In the 30 paired μCT and histological images containing necrotic lesions, the frequency of segments with trabecular microfractures in the superficial layers (55% at μCT/51% at histology) was statistically significantly higher than in the deep layer (25% P 2.0/20.0 and mean long/short axis ratio > 2.35/2.2, respectively. Segments with bone microfractures predominate in necrotic lesions. Segments with trabecular microfractures form elongated clusters near the femoral head surface. [Display omitted] •Cortical and trabecular bone microfractures are frequent in collapsed ON femoral heads and are ubiquitous.•Trabecular microfractures predominate in the superficial layer of the epiphysis and form elongated clusters.•Microfractures in viable areas of ON and OA femoral heads are scattered and do not form clusters.