Fracture toughnessIn materials science, fracture toughness is the critical stress intensity factor of a sharp crack where propagation of the crack suddenly becomes rapid and unlimited. A component's thickness affects the constraint conditions at the tip of a crack with thin components having plane stress conditions and thick components having plane strain conditions. Plane strain conditions give the lowest fracture toughness value which is a material property.
Bone resorptionBone resorption is resorption of bone tissue, that is, the process by which osteoclasts break down the tissue in bones and release the minerals, resulting in a transfer of calcium from bone tissue to the blood. The osteoclasts are multi-nucleated cells that contain numerous mitochondria and lysosomes. These are the cells responsible for the resorption of bone. Osteoblasts are generally present on the outer layer of bone, just beneath the periosteum. Attachment of the osteoclast to the osteon begins the process.
Segond fractureThe Segond fracture is a type of avulsion fracture (soft tissue structures pulling off fragments of their bony attachment) from the lateral tibial plateau of the knee, immediately below the articular surface of the tibia (see photo). Because of the high rate of associated ligamentous and meniscal injury, the presence of a Segond or reverse Segond fracture requires that these other pathologies must be specifically ruled out. Or more pragmatically, the orthopaedic team assume that the presence of Segond fracture equals ACL rupture, as the correlation is close to 100%.
MenopauseMenopause, also known as the climacteric, is the time when menstrual periods permanently cease, marking the end of reproduction. It typically occurs between the ages of 45 and 55, although the exact timing can vary. Menopause is usually a natural change. It can occur earlier in those who smoke tobacco. Other causes include surgery that removes both ovaries or some types of chemotherapy. At the physiological level, menopause happens because of a decrease in the ovaries' production of the hormones estrogen and progesterone.
Primary ovarian insufficiencyPrimary ovarian insufficiency (POI) (also called premature ovarian insufficiency, premature menopause, and premature ovarian failure) is the partial or total loss of reproductive and hormonal function of the ovaries before age 40 because of follicular (egg producing area) dysfunction or early loss of eggs. POI can be seen as part of a continuum of changes leading to menopause that differ from age-appropriate menopause in the age of onset, degree of symptoms, and sporadic return to normal ovarian function.
