Contents
What is a stress riser orthopedics?
Abstract. Background: A stress-riser fracture develops when stress in an object is higher than that in the surrounding material. The aim of this retrospective study was to evaluate all consecutive femoral stress-riser fractures during a period of >10 years and to verify high-risk factors by using mechanical analysis.
What is meant by stress raiser?
Stress-raisers are sharp corners, grooves, notches or acute changes of section that cause stress concentrations under normal loadings. They can be found on both rotating and static components. The stress concentration factors of sharp corners and grooves are high, and difficult to determine accurately.
What is stress riser in medical terms?
A mechanical defect, such as a hole, in bone or other materials, which concentrates stress in the area and increases the risk of failure of the bone or material at that site.
What is fastener stress concentration?
For the deep thread models the stress concentration factor increases 6.67 percent between the 12 and 16-mm bolts, 0.97 percent between the 16-mm and 20-mm bolts, and 0.97 percent between the 20 and 24-mm bolts. The values are 3.18, 3.23, 3.63, 3.58, and 3.90 for the 8, 12, 16, 20, and 24-mm bolts.
What is stress shielding effect?
Stress shielding refers to the reduction in bone density (osteopenia) as a result of removal of typical stress from the bone by an implant (for instance, the femoral component of a hip prosthesis).
What causes stress concentration?
Stress concentrations occur when there are irregularities in the geometry or material of a structural component that cause an interruption to the flow of stress. This arises from such details as holes, grooves, notches and fillets. Stress concentrations may also occur from accidental damage such as nicks and scratches.
Why does stress shielding occur?
Stress shielding-related bone loss occurs after total hip arthroplasty because the stiffness of metallic implants differs from that of the host femur. Although reducing stem stiffness can ameliorate the bone resorption, it increases stress at the bone-implant interface and can inhibit fixation.
What is strain shielding?
Strain shielding, a mechanical effect occurring in structures combining stiff with more flexible materials, is considered to lead to a reduction of density in bone surrounding the implant. This effect can be related to the weakness of the implant fixation, which can promote implant loosening.
What are the stresses on a stress riser?
This limit ensures that the maximum tension applied to the riser is within the capacity of the riser connector. In this check, axial, bending, and hoop stresses are considered. In addition to maximum stresses, alternating stresses are limited by a recipe given in the API RP 16Q.
When to remove a stress riser in bone?
Just like the posts on the highway, stress risers in bone will be a focal area for fracture. That’s why your doctor will often remove your hardware after internal fixation is used to treat a fracture. Stress risers are probably the only downside of the science of fixation as described by the AO Foundation in Davos, Switzerland.
What does stress Ris ER mean in medical terms?
stress ris·er (stres rīz’ĕr), A mechanical defect, such as a hole, in bone or other materials, which concentrates stress in the area and increases the risk of failure of the bone or material at that site. Farlex Partner Medical Dictionary © Farlex 2012
What causes a stress riser in a femoral pipe?
The weakening of the proximal bony support can lead to a stress riser between the region without bone ingrowth and the distal well-fixed femoral disphysis. To date, the company has identified three contributing factors – the presence of a stress riser, differential soil settlement, and excessive stress at the bottom of the pipe.