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

Jenkins PJ, Ramaesh R, Pankaj P, Patton JT, Howie CR, Goffin JM, Merwe Av, Wallace RJ, Porter DE, Simpson AH - Acta Orthop (2013)

Bottom Line: The greatest density and trabecular thickness was found in the central core that extended from the medial calcar to the physeal scar.The weakest area was found at the apex and peripheral areas of the head.The apical region was weaker.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics , University of Edinburgh.

ABSTRACT

Background and purpose: The 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 methods: 6 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.

Results: The 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.

Interpretation: The 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.

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Arrangement of volumes of interest (VOIs) on 2 planes orthogonal to the neck axis (z-direction). Plane 1 was located orthogonal to the neck axis halfway between the center of the head and the apex. Plane 2 was located similarly at the center of the head. The center was defined as the center of the largest sphere that could be contained in the femoral head.
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Figure 1: Arrangement of volumes of interest (VOIs) on 2 planes orthogonal to the neck axis (z-direction). Plane 1 was located orthogonal to the neck axis halfway between the center of the head and the apex. Plane 2 was located similarly at the center of the head. The center was defined as the center of the largest sphere that could be contained in the femoral head.

Mentions: The maximal diameter of the femoral head was measured. Thereafter, a virtual sphere was used to describe the femoral head, with the diameter fitting this maximal diameter. The z-axis of the scan was defined as a line passing up the center of the femoral neck. The point where it exited the femoral head was defined as the apex. This plane was defined anatomically and the x- and y-planes were defined orthogonal to this plane (Figure 1).


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

Jenkins PJ, Ramaesh R, Pankaj P, Patton JT, Howie CR, Goffin JM, Merwe Av, Wallace RJ, Porter DE, Simpson AH - Acta Orthop (2013)

Arrangement of volumes of interest (VOIs) on 2 planes orthogonal to the neck axis (z-direction). Plane 1 was located orthogonal to the neck axis halfway between the center of the head and the apex. Plane 2 was located similarly at the center of the head. The center was defined as the center of the largest sphere that could be contained in the femoral head.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3822129&req=5

Figure 1: Arrangement of volumes of interest (VOIs) on 2 planes orthogonal to the neck axis (z-direction). Plane 1 was located orthogonal to the neck axis halfway between the center of the head and the apex. Plane 2 was located similarly at the center of the head. The center was defined as the center of the largest sphere that could be contained in the femoral head.
Mentions: The maximal diameter of the femoral head was measured. Thereafter, a virtual sphere was used to describe the femoral head, with the diameter fitting this maximal diameter. The z-axis of the scan was defined as a line passing up the center of the femoral neck. The point where it exited the femoral head was defined as the apex. This plane was defined anatomically and the x- and y-planes were defined orthogonal to this plane (Figure 1).

Bottom Line: The greatest density and trabecular thickness was found in the central core that extended from the medial calcar to the physeal scar.The weakest area was found at the apex and peripheral areas of the head.The apical region was weaker.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics , University of Edinburgh.

ABSTRACT

Background and purpose: The 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 methods: 6 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.

Results: The 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.

Interpretation: The 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.

Show MeSH
Related in: MedlinePlus