Limits...
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.

Show MeSH

Related in: MedlinePlus

Coronal reformat of microCT scan of a femoral head and neck. The columns represent the major trabecular groups and physeal scar.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3822129&req=5

Figure 8: Coronal reformat of microCT scan of a femoral head and neck. The columns represent the major trabecular groups and physeal scar.

Mentions: We postulate a model of femoral head structure whereby the strongest bone is located at the center of the femoral head. This area coincides with the intersection of the compressive trabecular groups from the medial calcar and greater trochanter, along with the area of physeal scar (Figure 8). Placement of the screw in this “middle/middle” area may ensure that the implant device gains fixation in this area. “Inferior/middle” placement may also achieve stable fixation superior to the implant. Using TAD alone may result in the acceptance of superiorly, anteriorly, or posteriorly placed implants, leading to a higher risk of failure. This risk may increase further in smaller femoral heads. The surgeon should consider the particular characteristics of the implant used and the area of the implant that achieves fixation. This study has shown that the subchondral bone at the apex of the femoral head is of low density and strength.


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)

Coronal reformat of microCT scan of a femoral head and neck. The columns represent the major trabecular groups and physeal scar.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 8: Coronal reformat of microCT scan of a femoral head and neck. The columns represent the major trabecular groups and physeal scar.
Mentions: We postulate a model of femoral head structure whereby the strongest bone is located at the center of the femoral head. This area coincides with the intersection of the compressive trabecular groups from the medial calcar and greater trochanter, along with the area of physeal scar (Figure 8). Placement of the screw in this “middle/middle” area may ensure that the implant device gains fixation in this area. “Inferior/middle” placement may also achieve stable fixation superior to the implant. Using TAD alone may result in the acceptance of superiorly, anteriorly, or posteriorly placed implants, leading to a higher risk of failure. This risk may increase further in smaller femoral heads. The surgeon should consider the particular characteristics of the implant used and the area of the implant that achieves fixation. This study has shown that the subchondral bone at the apex of the femoral head is of low density and strength.

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