Volume And Distribution Of Necrotic Area In Patients With Osteonecrosis Of The Femoral Head:3-dimensional Anatomical Study

Objective: To investigate the volume and distribution of femoral head necrosis in Association Research Circulation Osseous(ARCO)stage I,Ⅱ,and Ⅲ by three-dimensional reconstruction.Materials and methods: A total of 56 patients(91 hips)diagnosed as having osteonecrosis of the femoral head,but with no collapse,were included in this study.All patients underwent X-ray and MRI examination of the hip joint and ARCO staging before operation.A three-dimensional reconstruction was performed using Mimics 15.0 software based on preoperative MRI data.The femoral head was divided into eight regions using three-dimensional coordinates,which were established based on the anterior plane of the femoral neck using 3-matic 7.0 software.We calculated the volume of the necrosis of the femoral head and analyzed the necrosis distribution in different ARCO stages.Results: The volume and distribution of the necrosis of the femoral head correlated with ARCO stages.The largest necrosis volume distribution was not similar in different ARCO stages.The necrosis volume of ARCO ⅡC and ARCO ⅢB was significantly higher than that of ARCO I and IB.In the eight regions of the femoral head,the harder-hit region was the posterior superior medial(PSM)region in ARCO IA and IB.In ARCO ⅡA,the volume was mainly distributed in the PSM region;in ARCO ⅡB,in the anterior superior medial(ASM)and PSM regions;in ARCO ⅡC,in the PSM and anterior superior lateral(ASL)regions;and in ARCO ⅢB,in the ASL region.Conclusion: Based on the division of the femoral head by three-dimensional coordinates,which were set up based on the anterior plane of the femoral neck,differences in the distribution of the largest necrosis volume in different ARCO stages were observed,which provides essential information for clinical treatment.