ObjectiveTo observe the volume and distribution of necrotic tissue of femoral head in steroid-induced osteonecrosis of femoral head (SONFH) patients by three-dimensional reconstruction of CT.MethodsA clinical data of 25 patients with SONFH between September 2016 and December 2018 was analyzed. There were 22 males and 3 females, with an average age of 38.8 years (range, 20-63 years). The necrosis of the femoral head was in stage Ⅱ of Association Research Circulation Osseous (ARCO). The disease duration ranged from 3 to 18 months, with an average of 9.2 months. A three-dimensional reconstruction with CT data of SONFH patients were performed by Mimics Research 21.0 software and the femoral head was segmented into eight regions by 3-matic Research 13.0 software. The volume of necrotic tissue of the femoral head and the volume rate of necrotic tissue to femoral head were calculated and the distribution was also analyzed.ResultsThe three-dimensional digital model of the femoral head showed that the necrotic tissue of the femoral head was located above the anterior superior medial, and the area of the necrotic tissue was in a dome-like shape. The results showed that the necrotic tissue in the femoral head was mainly concentrated on the anterior superior internal area, the anterior superior outer area, and the posterior superior internal area. The volume of femoral head was (48 399.52±9 408.90) mm3, and the volume of necrotic tissue was (20 917.08±6 566.94) mm3, and the volume ratio of necrotic tissue to femoral head was 44.75%±15.72%. The proportion of necrotic volume in different regions was different, and the necrotic tissues were mainly distributed in the anterior superior internal area, the anterior superior outer area, and the posterior superior internal area.ConclusionThe volume and distribution of necrotic tissue in femoral head can be evaluated quickly and intuitively by three-dimensional reconstruction of CT in Mimics software.