If an incorrect selection (either the head or sleeve) is made the sleeve can become stuck within an implant head, such as a hip implant head. In such circumstances, manual force applied directly by a user, i.e. without the aid of a device/tool, can be insufficient to remove the sleeve. Accordingly, a suitable device is required.
Existing taper sleeves have an internal screw thread at the base of the taper. To remove such taper sleeves, a device with a threaded spigot is used to thread through the bottom surface of the taper sleeve and bear against the recessed internal face of the implant head, thereby forcing the sleeve and the implant head apart. Such a device will not work with a sleeve lacking a screw thread.
Such sleeves require there to be sufficient space for a bottom surface at the base of the sleeve. In some cases where space is limited there is not sufficient space and therefore such sleeves cannot be used.
Sleeves having threaded portions are more difficult to manufacture than those without threaded portions.
Sleeves having threaded portions are prone to failure due to thread burring caused by the threaded spigot separation device.
USPTO Backgrounds
USPTO Backgrounds