A micro-architectural evaluation of osteoporotic human femoral heads to guide implant placement in proximal femoral fractures

Abstract

Background and purposeThe micro-architecture of bone has been increasingly recognized as an important determinant of bone strength. Successful operative stabilization of fractures depends on bone strength. We evaluated the osseous micro-architecture and strength of the osteoporotic human femoral head.Material and methods6 femoral heads, obtained during arthroplasty surgery for femoral neck fracture, underwent micro-computed tomography (microCT) scanning at 30 μm, and bone volume ratio (BV/TV), trabecular thickness, structural model index, connection density, and degree of anisotropy for volumes of interest throughout the head were derived. A further 15 femoral heads underwent mechanical testing of compressive failure stress of cubes of trabecular bone from different regions of the head.ResultsThe greatest density and trabecular thickness was found in the central core that extended from the medial calcar to the physeal scar. This region also correlated with the greatest degree of anisotropy and proportion of plate-like trabeculae. In the epiphyseal region, the trabeculae were organized radially from the physeal scar. The weakest area was found at the apex and peripheral areas of the head. The strongest region was at the center of the head.InterpretationThe center of the femoral head contained the strongest trabecular bone, with the thickest, most dense trabeculae. The apical region was weaker. From an anatomical and mechanical point of view, implants that achieve fixation in or below this central core may achieve the most stable fixation during fracture healing.

Linear viscoelasticity - bone volume fraction relationships of bovine trabecular bone

“…treatment of proximal femoral fractures (using sliding hip screws or gamma nails) (Jenkins et al. 2013; Goffin et al. 2013, 2014), and in total knee replacements (Meneghini et al.…”

Comparison of the Lag Screw Placements for the Treatment of Stable and Unstable Intertrochanteric Femoral Fractures regarding Trabecular Bone Failure

“…It was assumed that the femur consisted of isotropic material and homogeneous trabecular bone density. Upon taking a glance at studies about bone density, we realized that the central region of the femoral head had the strongest trabecular bone, whereas the superior regions of the head had the weakest trabecular bone [29, 30]. Under these circumstances, the cut-out risk may increase at the superior region and decrease at the center and inferior regions.…”

“…A significant number of clinical studies have been carried out for the relation between TAD and the cut-out. These studies regard TAD as the best predictor for the cut-out risk [5, 9–12, 30]. Nevertheless, it is not an accurate predictor in that it cannot reflect the inhomogeneous distribution of the bone in femoral head regions [9].…”

Focal osteoporosis defects play a key role in hip fracture

“…In older adults, those regions have often become thin and porous through decades of age-associated bone loss, since they are stress-shielded during activities such as walking [8]. Micro CT measurements of trabecular bone from femoral head and neck biopsies support this notion, with substantially more bone present in areas directly loaded by walking than in fracture-prone zones [9], [10].…”