Automatic planning and geometric analysis of the drilling path in core decompression surgery for osteonecrosis of the femoral head

Background and Objective: Core decompression surgery is an effective treatment method for patients with precollapse osteonecrosis of the femoral head (ONFH). The treatment relies on accurately predrilling the wire into the necrotic lesion. However, the surgical planning of this drilling path remains unclear. This paper aims to develop a framework to automatically plan the drilling path and analyze its geometric parameters. Methodology: The proposed system consists of two stages. The first stage is to detect the key points. Besides the entry point and target point for the drilling path, the center of the femoral head (FH) and the boundary points of the necrotic lesion are also detected for the subsequent geometric analysis. In the second stage, the geometric parameters of the drilling path are analyzed, including the size of the necrotic lesion, the length from the entry point to the target point, the relative location between the FH center and the necrosis center, and the angular range of the drilling path in the anterior -posterior (AP) direction and superior -inferior (SI) direction. Results: All of the drilling paths designed by the proposed system were considered successful, starting from the proximal subtrochanteric region, terminating at the center of the necrotic lesion, and remaining within the femoral neck. The relative coordinates of the centers of the femoral head and necrotic lesion were (-0.89, 5.14, 2.63) mm for the left femurs and (1.55, 5.92, 2.63) mm for the right femurs, on average. The angular range of the drilling path was 39.99 +/- 29.58 degrees in the SI direction and 46.18 +/- 40.73 degrees in the AP direction. Conclusion: This study develops a framework that allows for automatic planning and geometric analysis of the drilling path in core decompression surgery. The target point of the drilling path primarily resides in the lateralanterior -superior region relative to the femoral head center. Surgeons and researchers can benefit from our unified framework while still maintaining the flexibility to adapt to variations in surgical cases.