Knee bar

Knee bar is the spaced-form name for the kneebar — the leg-lock submission in which the attacker forces the opponent’s leg into full extension to load the knee joint past safe range.

Etymology. “Knee bar” with a space is the alternate orthographic form of “kneebar.” Both spellings appear in instructional material; the closed form predominates in published vocabulary.

Mechanics. The leg extension loads the knee against its natural hinge range — the lock finishes faster than an armbar because the knee has a shorter hyperextension margin than the elbow.

Cross-reference. “Leg straightener” is the descriptive alternate. Full mechanical coverage on Kneebar.