Clinical biomechanics
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Clinical biomechanics · Aug 2014
Biomechanical effects of calcar screws and bone block augmentation on medial support in locked plating of proximal humeral fractures.
The objective of this study was to investigate the biomechanical effects of medial fracture gap augmentation in locked plating of an unstable 2-part proximal humeral fracture with calcar screws and insertion of a corticocancellous bone block. Furthermore the mechanical behavior of dynamic locking screws in the non-parallel arrangement of a proximal humeral plate was of interest. ⋯ Additional calcar screws alone did not improve the initial biomechanical properties of an unstable 2-part proximal humeral fracture model. However bone block augmentation appeared to be a reliable alternative of additional bony support by raising stiffness and failure load. Dynamic locking screws did not show their expected dynamic component when used in a non-parallel arrangement.
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Clinical biomechanics · Aug 2014
Biomechanical assessment of composite versus metallic intramedullary nailing system in femoral shaft fractures: A finite element study.
Intramedullary nails are the primary choice for treating long bone fractures. However, complications following nail surgery including non-union, delayed union, and fracture of the bone or the implant still exist. Reducing nail stiffness while still maintaining sufficient stability seems to be the ideal solution to overcome the abovementioned complications. ⋯ Our results suggest that the composite nail can provide a preferred mechanical environment for healing, particularly in transverse shaft fractures. This may help bioengineers better understand the biomechanics of fracture healing, and aid in the design of effective implants.
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Clinical biomechanics · May 2014
Comparative StudyLocking plates and their effects on healing conditions and stress distribution: A femoral neck fracture study in cadavers.
Implants are used to stabilize femoral neck fractures to achieve successful fracture healing, but there is still a high rate of fracture non-unions. We compared micromotions in femurs with fractured femoral necks stabilized with three screws with or without a locking plate. We also investigated whether osteoporosis was associated with micromotion magnitudes, and explored the influence of implants on load distribution in the upper femur. ⋯ The locking plate group showed increased resistance to shear forces compared with the screw group. This effect was not associated with a diagnosis of osteoporosis. The locking plate did not affect the load distribution in the proximal femur.
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Clinical biomechanics · May 2014
Gait adaptation during walking on an inclined pathway following spinal cord injury.
Individuals with incomplete spinal cord injury need to be assessed in different environments. The objective of this study was to compare lower-limb power generation in subjects with spinal cord injury and healthy subjects while walking on an inclined pathway. ⋯ The most important differences are associated with the fact that individuals with spinal cord injury walk at a slower speed, except for the ankle power generation. This study demonstrated that, even with a good motor recovery, distal deficits remain and may limit the ability to adapt to uphill and downhill walking. Inclined pathways are indicated to train patients with spinal cord injury. Clinicians should focus on the speed of uphill and downhill walking and on the use of plantar flexors.
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Clinical biomechanics · May 2014
Comparative StudyBiomechanical behavior of MRI-signal-inducing bone cements after vertebroplasty in osteoporotic vertebral bodies: An experimental cadaver study.
Conventional water-free polymethylmethacrylate cements are not MRI visible due to the lack of free protons. A new MRI-visible bone cement was developed through the addition of a contrast agent and either a saline solution or a hydroxyapatite (Wichlas et al., 2010). The purposes of the study were to examine the influence of the two MRI-signal-inducing cements on the biomechanical behavior of cadaveric osteoporotic vertebral bodies after vertebroplasty and to compare the performance of the cements with conventional polymethylmethacrylate cement. ⋯ The elastic moduli of the cements appear to exert little influence on the biomechanical values when the cement is in the vertebral body. Based on the direct comparison with the classic polymethylmethacrylate cement, we believe that the implementation of such cements for MRI-guided vertebroplasties is feasible.