Joint lock

A joint lock is a grappling technique involving manipulation of an opponent's joints in such a way that the joints reach their maximal degree of motion.

In budo these are referred to as kansetsu-waza, "joint locking technique", and in Chinese martial arts as Chin na su which literally means "technique of catching and locking".

These typically involve isolating a particular joint, and leveraging it in an attempt to force the joint to move past its normal range of motion. Joint locks usually involve varying degrees of pain in the joints, and if applied forcefully and/or suddenly, may cause injury, such as muscle, tendon and ligament damage, even dislocation, or bone fractures.

Joint locks can be divided into five general types according to which section of the body they affect: These general types can be further divided into subtypes according to which specific joint(s) they affect, or the type of motion they involve.
 * Armlocks
 * Leglocks
 * Small joint manipulation
 * Spinal locks
 * Wristlocks

Usage
Joint locks are commonly featured in all forms of grappling, whether it be in martial arts, self-defense, combat sport or hand to hand combat application. The variants involving lesser leverage on a smaller joint (such as wristlocks) are often featured in law-enforcement or self-defense application, where they are used as pain compliance holds. Joint locks that involve full body leverage can on the other hand be used in hand to hand combat to partially or fully disable an opponent, by tearing major joints such as knees or elbows.

Common martial arts featuring joint locks include Aikido, Brazilian Jiu-Jitsu, Catch Wrestling, Hapkido, Jiu-Jitsu, Judo, Ninjutsu and mixed martial arts. They are usually practiced in a maximally safe manner, with controlled movements, and releasing the joint lock once it is apparent that it has been effectively applied. In combat sports, joint locks are used as submission holds, and are intended to force the opponent to submit; the lock will be controlled and held until an opponent submits or a referee recognizes the threat of injury and intervenes. The types of joint locks allowed in competitions featuring them varies according to the perceived danger in their application. Armlocks are generally considered safer, while small joint manipulation and spinal locks are banned in nearly all combat sports.

Main reference

 * Iverson, Steven. Unarmed Combat. Online excerpt: Atlasbooks. www.atlasbooks.com. URL last accessed March 6, 2006.