Often after an acute injury of the knee the quadriceps muscle will not contract, which is called âquad inhibition.â. Inability to straighten the leg. Athletes with acute patellar injuries may find that they cannot flex the knee joint fully or straighten the leg. This may be exacerbated by swelling of the knee.
The alkali metals are a group (column) in the periodic table consisting of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr).
1 The alkali metals make up group 1 of the Table, and comprise Li through Fr. They have very similar behavior and characteristics. 2  Hydrogen is group 1 but exhibits few characteristics of a metal and is often categorized with the nonmetals. 3  Alkaline earth metals.