A modular skeletal hook has an upper module for connecting with larger support apparatus to maintain bones of the skeleton in fixed relationship. The upper module is connected to an attachment module by a modified ball and socket arrangement. The attachment module has a C-shaped hook for engaging the bone. The angular orientation of the upper module and the attachment module may be fixed by a set screw threaded through the upper module and the attachment module.

FIELD OF THE INVENTION

This invention relates to the field of orthopedic surgery. Particularly, the invention is directed to skeletal fixation apparatus and implants having adjustable angular orientation between the bone attachment element and the rods or plates connected thereto.

BACKGROUND OF THE INVENTION

The purpose of the implant is to reinforce certain parts of the skeleton by use of strategically placed bone attachment devices. In some cases, these devices may support alignment support rods placed bilateral along the vertebrae as well as cross-link plates that bridge the spine.

Conventionally, pedicle screws are use to attach the implants to the bone. However, there are instances in which it is not desirable or possible to use screws. Other attachment devices, such as hooks, may be used when it is not desirable to penetrate the bone. Usually, these hooks or screws are rigid one piece constructions. Due to the various anomalies of the skeleton, occurring naturally or by trauma, it is difficult to place a series of attachments in such a manner that a uniformly shaped plate or rod can be connected without creating additional stress on the skeleton.

Further, in the case of the hooks there is the possibility of movement of the attachment point.

DESCRIPTION OF THE PRIOR ART

U.S. Pat. No. 5,397,363 discloses a spinal stabilization implant system using pedicle screws. Also shown and described are hooks for attaching to the vertebrae. These screws and hooks are one piece devices without adjustment capabilities.

What is needed in the art is a bone attachment device that may be optimally attached to the bone, as dictated by the anatomy, with modular construction permitting changes in angular orientation of a portion of the device for connecting to support apparatus.

SUMMARY OF THE INVENTION

A modular skeletal hook is disclosed having an upper module for connecting to a larger support apparatus for maintaining bones of the skeleton in fixed relationship. The upper module is connected to an attachment module by a modified ball and socket arrangement. The attachment module has a C-shaped hook for engaging the bone. The angular orientation of the upper module and the attachment module may be fixed by a set screw threaded through the upper module and the attachment module.

Accordingly, it is an objective of the instant invention to teach a modular construction having a bone attachment portion and a polyaxial support portion.

It is a further objective of the instant invention to teach a bone hook formed with a ball socket with a threaded aperture through the socket.

It is yet another objective of the instant invention to teach a support module having a spherical area adapted to fit into the socket of the bone hook. The spherical area includes an aperture therethrough. Opposite the spherical area, the support module has a threaded connector for connecting to skeletal support devices.

It is a still further objective of the invention teach a set screw which has multiple functions of connecting the two major modules together, maintaining any angular orientation between the modules, and positively attaching the device to the bone.

DETAILED DESCRIPTION OF THE INVENTION

The modular polyaxial bone fixation device10, shown inFIG. 1, has an upper module11formed with a U-shaped connector12. The connector12has external threads13about the upstanding legs14and15for accepting a threaded nut (not shown) to connect bone support apparatus between the legs. A cross section of a spinal rod16is shown in phantom lines. The bottom portion of the U-shaped connector12is shaped as a portion of a ball17or nearly spherical, shown in FIG.3. As shown, there is a flattened area18. The bottom portion17also has an aperture19therethrough.

The attachment module20has a socket portion21, shown inFIG. 2, shaped to accept the ball17of the connector module11. The upper edge of the socket portion21has serrations22which act as stops for rotation when assembled. The socket portion has an aperture23extending through the thickened lower wall. The aperture has internal threads27to cooperate with the threads28of the set screw26.

Depending from the socket21is the C-shaped bone hook25, shown inFIG. 4, which attaches to the skeletal bone of a patient. The exterior and interior walls of the hook25are flattened for greater purchase on the bone. Aperture23penetrates the portion of the bone hook joined to the socket21. The set screw26, shown inFIG. 5, is threaded through the upper module and the attachment module to movably connect the two elements.

In use, the skeletal bone is exposed and an attachment site is chosen. The hook25is attached to the bone. If a series of the devices is necessary, the several separate hooks are placed. The support modules of the several devices are then brought into alignment for placing support apparatus by manipulating the support module in the attachment module. Once this alignment is established each of the set screws in each of the modular sets are tightened to fix the angular orientation of the support module to accept another apparatus spanning the several modules. The threaded set screw also contacts the bone within the arc of the C-shaped hook to positively fix the device. The other support apparatus is then placed in the aligned U-shaped modules and the nut is threaded onto the U-shaped module to secure the apparatus.