Medical devices in accordance with various embodiments of the present invention employ one or more coaxial screw gear sleeve mechanisms. In various embodiments, coaxial screw gear sleeve mechanisms include a post with a threaded exterior surface and a corresponding sleeve configured to surround the post, the corresponding sleeve having a threaded interior surface configured to interface with the threaded exterior surface of the post and a geared exterior surface. A drive mechanism can be configured to interface with the geared exterior surface of the sleeve, causing the device to expand.

Shoulder arthroplasty systems and configurations for components thereof are described. For example, implant systems for a total should arthroplasty (TSA), hemi shoulder arthroplasty, and reverse should arthroplasty (RSA) are described. In addition, exemplary configurations for baseplates, glenoid components, glenosphere components, humeral components, humeral head components, humerosocket components, connectors, and adaptors, are described.

System, including methods and apparatus, for replacing an end of a bone, such as a radial bone, with a prosthesis. In exemplary embodiments, the prosthesis is a radial head prosthesis having a stem portion and a head portion. The head portion may be configured to be (a) placed onto the stem portion by movement of the head and stem portions relative to one another transverse to a longitudinal axis of the stem portion, and then (b) rotated with respect to the stem portion to produce friction that firmly attaches the head portion to the stem portion.

A facet joint replacement system includes an inferior implant with an inferior articular surface, a superior implant with a superior articular surface, and an optional crossbar. The inferior implant and the superior implant are each polyaxially adjustably connected to fixation elements which anchor the implants to adjacent vertebrae. The optional crossbar may be polyaxially adjustably connected to bilateral implants. The system components may be provided in kits which provide components of various sizes and shapes. A set of surgical instruments may facilitate implantation of the facet joint replacement system by providing tools for bone preparation, trialing, implant insertion, implant alignment, and lock-out of modular interconnections.

An intervertebral implant has a hollow space formed within the implant and accessible through an elongate opening extending through a recessed portion of the side wall, and the hollow space is shaped to receive an engagement portion of a drive shaft of an insertion tool; and the intervertebral implant includes at least two guiding surfaces facing each other and being configured for sliding engagement by a portion of a sleeve of the insertion tool movably holding the drive shaft.

Superior and/or inferior facets of one or more facet joints may be replaced by superior and/or inferior facet joint prostheses. In one embodiment, a kit of superior or inferior prostheses is provided, in which the prostheses have at least two dimensions that vary among members of the kit independently of each other. Each prosthesis may have a bone engaging surface having a surface that is polyaxially rotatable against a corresponding resection of a vertebra. Each prosthesis may also have an articulating surface shaped such that, after attachment to the spine, the replaced or partially replaced facet joints provide a larger medial-lateral range of motion when the spine is flexed than when the spine is extended. Crosslinks may be used to connect left and right prosthesis together in such a manner that they are stabilized in a position in which they are seated directly against the vertebra.

A trial kit for a hinged knee implant system is disclosed. The trial kit includes a tibial base plate trial, an adaptor and a tibial bearing insert trial. The adaptor and insert trial can be assembled and the assembly mounted on the tray trial by sliding the assembly in an anterior-posterior direction on the tray trial. The adaptor has a post with a cross-piece. The insert trial has openings and channels to receive the post and cross-piece. The openings are sized, shaped and oriented so that the cross-piece of the elongate post must be oriented in different directions to pass through the different openings.

Captured element shoulder joint implant may be configured with a captured humeral ball; in a reverse shoulder configuration; to have a barrel- or disc-like humeral head to recessed glenoid articulation; and so forth. Multi-point fixation glenoid component may be provided. A humeral implant may have a universal joint connection, which can be mounted to or in a humeral bone and provide for a center of movement generally within a volume defined by an upper head of a normal humerus.

A facet joint replacement system includes an inferior implant with an inferior articular surface, a superior implant with a superior articular surface, and an optional crossbar. The inferior implant and the superior implant are each polyaxially adjustably connected to fixation elements which anchor the implants to adjacent vertebrae. The optional crossbar may be polyaxially adjustably connected to bilateral implants. The system components may be provided in kits which provide components of various sizes and shapes. A set of surgical instruments may facilitate implantation of the facet joint replacement system by providing tools for bone preparation, trialing, implant insertion, implant alignment, and lock-out of modular interconnections.

Surgical cutting instruments and methods of use are described. The surgical cutting instrument (100) comprises an instrument body (102) with a first attachment mechanism (106) at a distal end. A cutter (104) has a central core (110), a plurality of cutting formations (130, 136) and a plurality of lobes (112, 114, 116) extending from the central core. The central core has side walls (118, 120, 122) which define an entirely open mouth and the side walls include a second attachment mechanism (140, 142, 144) which can interact with the first attachment mechanism to releasably attach the cutter to the distal end of the instrument body. At least one cutting formation (136) is provided on an end outer face (138) of the cutter opposite the entirely open mouth.