Abstract: A strut for use with an external fixation system may include first and second joints proximate the first and second ends of the strut, the first and second joints configured to couple to first and second rings of the external fixation system. The strut may include a threaded rod coupled to the first joint, a tube that receives the threaded rod, a fluctuation counter coupled to the tube, and a needle coupled to the fluctuation counter. The needle may extend through a bore in the outer tube, and the needle may have a free end in contact with the threaded rod. The strut may be an adjustable-length strut whereby the threaded rod is moveable axially into or out of the tube, and while the threaded rod moves into or out of the tube, the free end of the needle may be configured to maintain contact with the threaded rod.

Abstract: A strut for use with an external fixation system may include first and second joints proximate the first and second ends of the strut, the first and second joints configured to couple to first and second rings of the external fixation system. The strut may include a threaded rod coupled to the first joint, a tube that receives the threaded rod, a fluctuation counter coupled to the tube, and a needle coupled to the fluctuation counter. The needle may extend through a bore in the outer tube, and the needle may have a free end in contact with the threaded rod. The strut may be an adjustable-length strut whereby the threaded rod is moveable axially into or out of the tube, and while the threaded rod moves into or out of the tube, the free end of the needle may be configured to maintain contact with the threaded rod.

Abstract: A reference assembly connected to a support ring of an external fixation frame. The reference assembly includes a mount device. The mount device includes a mount body, a static member, and a dynamic member. The static member is fixedly secured to and extends from the mount body and is configured to be received within a first hole of the support ring of the external fixation frame. The dynamic member is slidably connected to the mount body and is configured to be received within a second hole of the support ring. The reference assembly also includes a reference device that is connectable to the mount body. The reference device includes reference body and a plurality of reference objects disposed within the reference body. The reference objects are each made from a radiopaque material, and the reference body is made from a radiolucent material.