Osteoblasts actively generate cell
traction force (CTF) to sense
chemical and mechanical microenvironments. Fluid shear stress (FSS)
is a principle mechanical stimulus for bone modeling/remodeling. FSS
and CTF share common interconnected elements for force transmission,
among which the role of the protein-material interfacial force (F
ad) remains unclear. Here, we found that, on
the low F
ad surface (5.47 ± 1.31
pN/FN), CTF overwhelmed F
ad to partially
desorb FN, and FSS exacerbated the desorption, resulting in disassembly
of the actin cytoskeleton and focal adhesions (FAs) to reduce CTF
and establishment of a new mechanical balance at the FN-material interface.
Contrarily, on the high F
ad surface (27.68
± 5.24 pN/FN), pure CTF or the combination of CTF and FSS induced
no FN desorption, and FSS promoted assembly of actin cytoskeletons
and disassembly of FAs, regaining new mechanical balance at the cell-FN
interface. These results indicate that F
ad is a mechanical regulator for transmission of CTF and FSS, which
has never been reported before.
Artificial joint revision surgery, as an increasingly common surgery in orthopedics, often requires patient-specific prostheses to repair the bone defect. Porous tantalum is a good candidate due to its excellent abrasion and corrosion resistance and good osteointegration. Combination of 3D printing technology and numerical simulation is a promising strategy to design and prepare patient-specific porous prostheses. However, clinical design cases have rarely been reported, especially from the viewpoint of biomechanical matching with the patient’s weight and motion and specific bone tissue. This work reports a clinical case on the design and mechanical analysis of 3D-printed porous tantalum prostheses for the knee revision of an 84-year-old male patient. Particularly, standard cylinders of 3D-printed porous tantalum with different pore size and wire diameters were first fabricated and their compressive mechanical properties were measured for following numerical simulation. Subsequently, patient-specific finite element models for the knee prosthesis and the tibia were constructed from the patient’s computed tomography data. The maximum von Mises stress and displacement of the prostheses and tibia and the maximum compressive strain of the tibia were numerically simulated under two loading conditions by using finite element analysis software ABAQUS. Finally, by comparing the simulated data to the biomechanical requirements for the prosthesis and the tibia, a patient-specific porous tantalum knee joint prosthesis with a pore diameter of 600 μm and a wire diameter of 900 μm was determined. The Young’s modulus (5719.32 ± 100.61 MPa) and yield strength (172.71 ± 1.67 MPa) of the prosthesis can produce both sufficient mechanical support and biomechanical stimulation to the tibia. This work provides a useful guidance for designing and evaluating a patient-specific porous tantalum prosthesis.
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