Micro computed tomography (Micro-CT) was used to analyze the structural characteristics of trabecular bone in the femoral head in patients with steroid-induced osteonecrosis of femeral head and femoral neck fracture.

From September 2016 to September 2017, patients who underwent artificial total hip arthroplasty due to femoral neck fracture and steroid-induced osteonecrosis of femeral head at Affiliated Zhongshan Hospital of Dalian University, the fracture group and necrotic group were set respectively, 20 cases each(20 hips). Each femoral head was removed as research material. Using a computer to do three-dimensional reconstruction of the femoral head, the femoral head was divided into 27 parts by 2 parallel planes of x, y and z axes, the numbering rules of the 27 areas were: divided into inner, middle and outer areas, each area was numbered 1-9 in the order from front to back and from top to bottom. The inner area numbers were m1, m2……, m9; the intermediate area numbers were c1, c2, ……, c9; the outer area numbers were l1, l2, ……, l9. A Micro-CT tomography scan of the sample was performed to obtain a three-dimensional computer image of the femoral head sample. Manually selected the area of interest, subsequently, three-dimensional spatial parameters such as bone volume fraction, trabecular thickness, trabecular bone number and trabecular space were used to evaluate the trabecular bone in femoral head for steroid-induced osteonecrosis of femeral head and femoral neck fracture. Data were compared with t test and one-way analysis.

In the fracture group, the femoral head was divided into the innor, medial, and lateral regions according to the sagittal plane for comparison. The median region showed the largest average bone volume fraction, the largest average thickness, the largest trabecular number and the smallest mean gap, the differences were statistically significant (F=36.59, 73.50, 38.60, 48.50; with P values below 0.05). The femoral head was divided into anterior, middle, and posterior regions according to the coronal plane for comparison. The anterior region showed the largest average bone volume fraction, the largest average thickness, the largest trabecular number and the smallest mean gap, the differences were statistically significant(F=69.50, 43.92, 85.40, 36.00; with P values below 0.05). According to the horizontal plane, it was divided into upper zone, middle zone and lower zone for comparison. The upper zone showed the highest average bone volume fraction, the largest average thickness, the largest trabecular number and the minimum mean gap, the differences were statistically significant(F=37.03, 29.47, 255.50, 45.50; with P values below 0.05). The microstructural parameters of the trabecular bone of different parts of the femoral head in the femoral head necrosis group were compared, if the femoral head was divided into the medial area, the intermediate area, and the lateral area, the median zone exhibits the largest average bone volume fraction, the largest average thickness, the largest number average, and the smallest gap mean of the dominant trabecular bone area, the differences are statistically significant(F=41.42, 26.60, 400.00, 36.00; with P values below 0.05). If the femoral head was divided into an upper zone, a middle zone, and an inferior zone, the superior zone exhibits the largest average bone volume fraction, the largest average thickness, the largest number average, and the smallest gap mean of the dominant trabecular bone area, the differences are statistically significant(F=52.99, 25.33, 28.50, 37.33; with P values below 0.05). If the femoral head was divided into anterior, intermediate, and posterior areas, the anterior area exhibits the largest average bone volume fraction, the largest average thickness, the largest number average, and the smallest gap mean of the dominant trabecular bone area, the differences are statistically significant(F=2 567.17, 57.29, 42.11, 41.17; with P values below 0.05). Compared with the necrosis group, the average value of trabecular bone volume fraction in each area of the fracture group was larger (t=4.90, P=0.01), the average value of trabecular bone thickness was greater (t=-4.17, P=0.01), the number of trabecular bone was larger (t=-31.37, P=0.01), and the mean value of trabecular bone gap was smaller (t=-7.12, P=0.01).

The effect of hormones on the necrotic femoral head is not only the necrotic area, including the sclerotic area and normal trabecular area, it affects the entire femoral head.