The qualitative analysis of trabecular architecture of the proximal femur based on the P45 sectional plastination technique.

The primary weight-bearing structure of the proximal femur, trabecular bone, has a complex three-dimensional architecture that was previously difficult to comprehensively display. This study examined the spatial architecture of trabecular struts in the coronal, sagittal, and horizontal sections of the proximal femur using 21 cases prepared with P45 sectional plasticization. The primary compressive strut (PCS) exhibited a "mushroom-like" shape with upper and lower parts. The lower part extended from the medial inferior cortical bone of the femoral neck to the central region of the femoral head, while the upper part radiated from the epiphyseal line to the subchondral cortical bone of the femoral head. The secondary compressive strut (SCS), originated below the distal end of the PCS, ran diagonally upward, and intersected with the secondary tensile strut (STS) within the greater trochanter. The primary tensile strut (PTS) comprised anterior (aPTS) and posterior (pPTS) components originating from the anterior- and posterior-superior cortical bone of the femoral neck. These converged, entered the femoral head, intersected with the PCS beneath the epiphyseal line, forming a dense trabecular center, and terminated at the subchondral cortical bone below the fovea of the femoral head. The secondary tensile strut (STS) originated from the cortical bone around the lower edge of the greater trochanter, converging upwards and medially to terminate at the superior cortical bone of the femoral neck. The trabecular system of the proximal femur consists of two subsystems: one between the femoral head and neck, and another between the femoral neck and shaft. The head-neck system comprises intersecting PCS, aPTS, and pPTS, facilitating stress transmission. The neck-shaft system features intersecting STS and SCS, enabling stress transmission between these regions. These independent systems are separated by Ward's triangle. The findings of this study offer anatomical guidance for the improvement of internal fixation methods, orthopedic implants, and the design of surgical robots.