A polyaxial pivot housing for an external fixation system, comprising a first plate； a second plate substantially parallel to the first plate； a spherical member positioned between the first and second plates, the spherical member having a threaded post that is configured to attach to a support member of an external fixation frame； and a pivotably rotatable locking arm, the locking arm being configured to orientationally lock the threaded post with respect to the external fixation frame by compressing the first and second plates against the spherical member.
