Cripple

Especially powerful blows to the Marine's legs can severely maim him, or otherwise compromise his Power Armor's leggings. This forces him to move with a limp, broken bones, and reduced power to his servo-joints. The end result is the same thing, a crippled soldier barely able to keep pace with his companions, and almost unable to outrun enemies.

Causes
Any hit has a very small chance to inflict cripple, so long as the hit brings the player under 80% life. However, hits inflicted by larger enemies such as Agrons and Slashers have a much higher chance because of their high damage amount.

Menoetes
The Mini-Boss Menoetes is infamous for his ability to cripple players. Although possessing no direct attack, the beast will summon Nydus Worms that almost always inflict cripple on whatever they hit. Through luck or skill, especially clever players can cause the boss to cripple himself, or even cripple Erebos. It should be worth noting that on top of crippling their victims, said worms inflict a steep amount of damage.

Time
There are very few sure-fire cures for Cripple. The easiest, if tedious, is to simply wait the three minutes until ailment wears off. However, your diminished ability to move, and therefore kite, will almost certainly make you a vulnerable burden on your teammates.

Surgical Laser
Hopefully, as with most teams, there will be a Medic at your disposal. The medic's skill Surgical Laser will instantly cure you, just make sure to remind him you're wounded.

Saline
While under the effect of repulse, Salines used by the Survival Rifleman will also cure cripple in addition to its other effects.

Combat Hardened
When playing as the venerable Subtlety Commando, the skill Combat Hardened will instantly cure cripple, so long as you have the energy to use it.