Patent Description:
This application further relates to customized, computer-aided bone distraction systems, wherein patient-specific customized bone plates or footplates matching the contours of the patient's anatomy are provided, the bone plates having been designed using virtual planning based on digitized data derived from the patient's anatomy, such as for example CT scan data. In a typical method, a virtual three-dimensional model of the bone is created, virtual bone plate templates conforming to the surface topography of the bone are created based on the virtual three-dimensional model, and then actual bone plates are produced based on the virtual bone plate templates. In this manner the customized bone plates conform to the surface topography or configuration of the patient's bone to provide an optimized fit onto the bone segments, including the locations of the mounting apertures so as to receive bone screws in the optimum locations for secure attachment and reduced damage to nerves or weak bone portions. Examples of computer-aided implant formation methodology are shown in <CIT>, <CIT>, and<CIT>.

The use of distractor devices to modify or reconstruct bones through osteogenesis is well known in the art. Such systems and methods are utilized in connection with mandibles, maxillae, midface, palates, craniums, thoracic bones and others. In a basic embodiment, the surgeon takes standardized, pre-manufactured bone plates (e.g., rectangular plates with an evenly spaced array of holes to receive bone screws) and contours the bone plates to the patient anatomy by hand. The surgeon then cuts then off the portion of the plate that is not needed and hopes that they are able to position the device such that it is in the proper vector. The use of computer-aided implant design in the non-distractor, i.e., fixed, systems and methods is also well known in the art. In this advanced embodiment, the surgeon, working from patient CT or similar computer-aided data showing patient anatomy, either alone or in conjunction with computer skilled technicians, determines the desired reconfiguration or movement of the bone, the optimum vector for distraction, which distraction device is preferred, where the osteotomy should be performed, and where the screw holes should be situated. A planned case report is prepared and an anatomical model is provided to the surgeon. The surgeon uses the plan and the model to contour standard bone plates, already attached to the distraction mechanism, and cuts off unnecessary portions of the plates. The surgeon then uses a provided cutting or marking guide to mark a few screw holes and the desired location and orientation of the osteotomy directly on the bone. If a cutting guide is provided, the guide is temporarily affixed to the bone and is used to cut the osteotomy. The cutting guide is then removed and the distraction device is mounted to the bone segments by affixing the bone plates, the distraction device being oriented and located as close to the optimum location and orientation as shown in the plan as they can get, which is dependent on the surgeon's ability to properly contour the bone plate and find the marked screw holes.

These and other known devices, systems and methods suffer from certain problems. For example, in the creation of typical customized distractor bone plates, the optimal distraction vector is not taken into consideration, such that the final configuration of the bone after osteotomy, elongation and then regeneration may not be optimal. Another problem is that plates are affixed after the osteotomy has been performed, making it more difficult to properly position and attach each bone plate on its bone segment, especially if one of the bone segments is unanchored, such as will occur for example with the anterior segment of a mandible if an osteotomy has been performed on both sides. Still another problem is that the osteotomy is performed freeform or with a separate cutting guide member.

It is the object of this invention to address these problems in various embodiments of the device. The following example, which represent background art that is useful for understanding the invention, provides an improved bone distraction device, method and system, wherein patient specific customized bone plates matching the patient's anatomy are provided, the bone plates having been designed using computer-aided virtual planning based on the patient's anatomy, whereby in addition to providing customized contoured bone plates relative to the anatomy, the location and orientation of the bone plates relative to the distraction mechanism is based on the desired distraction vector as determined by the surgeon. In this manner, when the bone plates are affixed to the bone segments using mechanical fasteners, the distraction mechanism will be properly oriented on the desired distraction vector once it is attached to the bone plates.

A further example provides a device, system and method wherein in certain embodiments the bone plates are created independent of the distraction mechanism, such that the bone plates are mechanically fastened, in interlocking manner or with mechanical fasteners, to the distraction mechanism, in a manner allowing for attachment, detachment and re-attachment. It is a further object to provide a device, system and method wherein in certain embodiments a set of bone plates is attachable to various types of distractor mechanisms. A further example provides a device, system and method wherein in certain embodiments at least one of the bone plates includes a cutting guide structure, such that the distraction device with attached bone plates can be affixed to the bone prior to creation of the osteotomy, the distraction mechanism removed from the bone plates to expose the cutting guide structure, the osteotomy performed with the bone plates affixed to the bone, and the distraction mechanism then re-attached to the bone plates.

In various examples is a device, system and method of distraction osteogenesis wherein patient-specific, customized bone or foot plates matching the surface contours of the patient's anatomy are provided, the bone plates having been designed using computer-aided virtual planning based on the patient's anatomy, whereby in addition to providing customized, contoured bone plates relative to the anatomy, the location and orientation of the bone plates relative to the distraction mechanism is based on the desired distraction vector as previously determined by the surgeon.

An example of computer-aided, virtual three dimensional model of the bone to be distracted is produced based on actual patient data showing patient anatomy. The optimal operational parameters are then determined, such as the desired reconfiguration or movement of the bone, the optimum vector for distraction, which distraction device is preferred, the location of the osteotomy to be performed, and the best locations for the screw holes. A preferred distraction mechanism or body is chosen and the desired bone plate shape and thickness is determined. Screw hole locations designed to find the best bone portions for secure attachment and to avoid damage to tissues, nerves, tooth roots, etc. are determined. From this input, virtual bone plate templates are produced having inner surfaces matching the surface contours, topography or configuration of the patient at the chosen affixation locations. This design information is then used to produce actual bone plates based on the virtual bone plates for connection to a distraction mechanism and implantation on the patient's bone.

The surgeon assembles the distractor device by attaching the modular bone plates onto the distraction mechanism. The fully assembled distractor device is then positioned and the bone plates are affixed to the bone with mechanical fasteners such as bone screws. Because the bone plates are contoured to the specific patient anatomy at chosen locations, the bone plates will only fit in the proper locations. The distraction mechanism is removed from the bone plates. The surgeon then cuts between the bone plates using a guide edge on at least one of the bone plates as a cutting guide. The bone plates may be configured such that a cutting gap is present between and defined by the two bone plates. Furthermore, at least one of the bone plates may be provided with a cutting guide shoulder, such as a raised or thickened edge portion, to help the surgeon make the osteotomy in the desired shape and location. The distraction mechanism is then screwed back on to bone plates. In this manner proper orientation and placement is guaranteed because the bone plates can only be affixed in one location on the bone and the distraction mechanism can only attach to the affixed bone plates in previously determined orientation such that the distractor mechanism is in the proper position and aligned on the proper vector.

In some cases, the surgeon may want a plate or multiple bone plates to remain affixed to the patient permanently on the bone after distraction and regeneration has been accomplished. These bone plates may be designed to be thickened and contoured on the exterior surface to increase strength or to provide a desired base for cosmetic purposes.

According to the invention is a bone distractor device comprising: a distractor mechanism, a first bone plate and a second bone plate, wherein the first bone plate and second bone plate are releasably attached to the distractor mechanism and structured for attachment to a bone, and wherein the first bone plate and the second bone plate are configured using computer-aided design to conform to the exterior surface of the bone; wherein at least one of the first bone plate and second bone plate is provided with a guide edge, the guide edge determining the location of an osteotomy and guiding a bone saw through the bone after the distractor device is affixed to the bone and the distractor mechanism is detached from the first and second bone plates. The invention further comprises such device wherein the at least one of the first bone plate and second bone plate having a guide edge further comprises a guide shoulder; wherein the guide edge is provided on both the first bone plate and the second bone plate; further comprises a first connector assembly attaching the first bone plate to the distractor mechanism and a second connector assembly attaching the second bone plate to the distractor mechanism; the first connector assembly comprising a plate connector extension disposed on the first bone plate, a plate connector member disposed on the plate connector extension, a body connector member disposed on the distractor mechanism, and a connection fastener received in the body connector member which mates with the body connector member; the second connector assembly comprising a plate connector extension disposed on the second bone plate, a plate connector member disposed on the plate connector extension, a body connector member disposed on the distractor mechanism, and a connection fastener received in the body connector member which mates with the body connector member; and/or wherein the exterior surfaces of the first bone plate and the second bone plate are configured to present a cosmetically appealing support surface for overlying tissue.

Not being part of the invention, an example describes a bone distraction method comprising the steps of:
creating a virtual three-dimensional model of a bone to be distracted using computer-aided design; determining desired affixation locations on the virtual three-dimensional model for a first bone plate and a second bone plate and determining a desired distraction vector; creating a virtual three-dimensional template of a first bone plate and a virtual three-dimensional template of a second bone plate such that the inner surface of the virtual three-dimensional first bone plate template conforms to the surface topography of the bone at the desired attachment location for the virtual three-dimensional first bone plate template on the virtual three-dimensional model and the inner surface of the virtual three-dimensional second bone plate template conforms to the surface topography of the bone at the desired attachment location virtual three-dimensional second bone plate template on the virtual three-dimensional model; determining the desired osteotomy location on the bone, and creating a virtual guide edge defining the desired osteotomy location on at least one of the virtual three-dimensional first bone plate template and second bone plate template; creating a first bone plate based on the virtual three-dimensional first bone plate template and a second bone plate based on the virtual three-dimensional second bone plate template, the inner surfaces of each bone plate conforming to the exterior surface of the bone at the affixation location and the guide edge defining the osteotomy location on the bone; providing a distraction mechanism, wherein the first bone plate and the second bone plate are releasably attachable to the distraction mechanism to create a distractor device such that the distraction mechanism is oriented in the desired distraction vector when the distractor device is affixed to the bone; attaching the first bone plate the second bone plate to the distraction mechanism; affixing the first bone plate and the second bone plate to the bone; detaching the distraction mechanism from the first and second bone plates; performing an osteotomy on the bone using the guide edge to create a first bone segment and a second bone segment wherein the first bone plate is affixed to the first bone section and the second bone plate is affixed to the second bone segment; and re-attaching the bone distractor to the first and second bone plates and incrementally distracting the bone segments during osteogenesis. Further, such method wherein the step of creating a virtual guide edge comprises creating a virtual guide edge on both the virtual three-dimensional first bone plate template and on the virtual three-dimensional second bone plate template.

With reference to the drawings, which are provided for illustrative and descriptive purposes of disclosure and are not intended to be limiting, the device of the invention is now described.

The invention in various embodiments is a device of distraction osteogenesis wherein patient-specific, customized bone or foot plates <NUM>/<NUM> matching the surface contours of the patient's bone are provided using known computer-aided design and manufacturing technology, whereby in addition to providing customized, contoured bone plates relative to the bone structure, the location and orientation of the bone plates <NUM>/<NUM> relative to the distraction mechanism <NUM> is based on the desired distraction vector as previously determined by the surgeon.

Not being part of the invention, a computer-aided, virtual three dimensional model of the bone <NUM> to be distracted is produced based on actual patient data showing patient anatomy. The optimal operational parameters are then determined, such as the desired reconfiguration or movement of the bone segment or segments <NUM>/<NUM>, the optimum vector for distraction, which distractor device <NUM> is preferred, the location of the osteotomy <NUM> to be performed, and the best locations for the plate apertures or screw holes <NUM>. A preferred distraction mechanism or body <NUM> is chosen and the desired bone plate <NUM>/<NUM> shape and thickness is determined. Screw hole <NUM> locations designed to find the best areas of the bone <NUM> for secure attachment and to avoid damage to tissues, nerves, tooth roots, etc. are determined. From this input, virtual bone plate templates are produced having inner surfaces matching the surface topography or configuration of the patient's bone <NUM> at the chosen locations.

In addition to the overall configuration and shape of the bone plates <NUM>/<NUM>, a virtual guide edge is determined for at least one of the virtual templates using the computer-aided, virtual three-dimensional model, the virtual guide edge being an indicator for the desired location of the osteotomy <NUM> and providing a physical structure to at least partially control the movement of the cutting saw during creation of the osteotomy <NUM>. The virtual guide edge may be linear or non-linear as required. All of the design information is then used to produce actual first and second bone plates <NUM>/<NUM> based on the virtual bone plate templates for connection to a distraction mechanism <NUM> and implantation on the patient's bone <NUM>. Both the first and second bone plates will have inner surfaces corresponding and conforming to the exterior surface of the bone <NUM> at the affixation location for each. At least one of the first and second bone plates <NUM>/<NUM> is provided with a cutting guide <NUM>.

The surgeon assembles the distractor device <NUM> by attaching the modular first and second bone plates <NUM>/<NUM> onto the distraction mechanism <NUM> in readily detachable manner. For example, a first connector assembly <NUM> comprising a plate connector member <NUM>, such as a threaded rod, mounted onto a plate connector extension <NUM>, such as an arm, foot or flange, is structured to releasably mate with a body connection fastener <NUM>, such as an internally threaded screw, retained within a body connector member <NUM> affixed to the distraction mechanism <NUM>, such that the first bone plate <NUM> is connected to the distraction mechanism <NUM> in a manner that allows the distraction member <NUM> to be detached from and then re-attached to the first body plate <NUM> after the first body plate <NUM> has been affixed to the bone <NUM> using bone screws <NUM> disposed in screw-receiving apertures <NUM>. In like manner, a second connector assembly <NUM> comprising a plate connector member <NUM>, such as a threaded rod, mounted onto a plate connector extension <NUM>, such as an arm, foot or flange, is structured to releasably mate with a body connection fastener <NUM>, such as an internally threaded screw, retained within a body connector member <NUM> affixed to the distraction mechanism <NUM>, such that the second bone plate <NUM> is connected to the distraction mechanism <NUM> in a manner that allows the distraction member <NUM> to be detached from and then re-attached to the second body plate <NUM> after the second body plate <NUM> has been affixed to the bone <NUM> using bone screws <NUM> disposed in screw-receiving apertures <NUM>. Alternative embodiments for the first and second connector assemblies <NUM>/<NUM> utilizing different connection fasteners or mechanical interlocking structures may be used, provided the bone plates <NUM>/<NUM> are detachable and re-attachable after the bone plates <NUM>/<NUM> have been affixed to the bone <NUM>.

The fully assembled distractor device <NUM> is positioned on the patient's bone. Because the inner surfaces of the bone plates <NUM>/<NUM> are contoured to conform to the exterior surface of the patient's bone <NUM>, the bone plates <NUM>/<NUM> only seat properly in the desired locations. The bone plates <NUM>/<NUM> are then affixed to the bone <NUM> with bone screws <NUM> such as bone screws. The location and orientation of the distractor device <NUM> now correlates to the desired location and distraction vector as previous determined during the computer-aided design steps.

The distraction mechanism <NUM> is then removed from the bone plates <NUM>/<NUM>, as shown in <FIG>. This exposes the guide edge <NUM>, such that the surgeon knows the precise proper location for the osteotomy as previously determined during the computer-aided design stage. The guide edge <NUM> may be disposed on the first bone plate only, as shown in <FIG>, on the second bone plate <NUM>, as shown in <FIG>, or on both bone plates <NUM>/<NUM>, as shown in <FIG>, which creates a defined cutting gap. In a preferred embodiment, as shown in <FIG>, at least one of the bone plates <NUM>/<NUM> is provided with a guide shoulder <NUM>, a raised edge portion at the guide edge <NUM> which is thicker than the bone plate <NUM>/<NUM> to better guide the cutting saw during the osteotomy.

The surgeon then cuts between the bone plates <NUM>/<NUM>, using the guide edge or edges <NUM> as a cutting guide, to produce a first bone segment <NUM>, to which the first bone plate <NUM> remains affixed, and a second bone segment <NUM>, to which the second bone plate <NUM> remains affixed. Once the osteotomy has been performed, as shown in <FIG>, the distraction mechanism <NUM> is then re-attached to the bone plates <NUM>/<NUM>. In this manner proper orientation and placement of the distractor device <NUM> is guaranteed because each of the bone plates <NUM>/<NUM> remain properly affixed on the bone segments <NUM>/<NUM> in the pre-chosen location and orientation, and the distraction mechanism can only attach to the affixed bone plates in the previously determined orientation.

With the bone plates <NUM>/<NUM> secured to the distraction mechanism <NUM>, the distractor device <NUM> may now be utilized in regular manner to slowly reposition and elongated the bone <NUM> by gradually increasing the distance between the first and second bone segments <NUM>/<NUM> as bone regeneration occurs within the osteotomy gap <NUM>. Once the process is completed, the distraction mechanism <NUM> and the bone plates <NUM>/<NUM> are removed from the bone <NUM>.

Claim 1:
A bone distractor device comprising:
a distractor mechanism (<NUM>), a first bone plate (<NUM>) and a second bone plate (<NUM>), wherein the first bone plate (<NUM>) and second bone plate (<NUM>) are releasably attached to the distractor mechanism (<NUM>) and structured for attachment to a bone (<NUM>), and wherein the first bone plate (<NUM>) and the second bone plate (<NUM>) are configured using computer-aided design to conform to the exterior surface of the bone (<NUM>);
wherein at least one of the first bone plate and second bone plate (<NUM>, <NUM>) is provided with a guide edge (<NUM>), wherein the guide edge (<NUM>) is configured to define the location of an osteotomy and to guide a bone saw through the bone (<NUM>) after the distractor device is affixed to the bone (<NUM>) and the distractor mechanism (<NUM>) is detached from the first and second bone plates (<NUM>, <NUM>); and
the at least one of the first bone plate and the second bone plate (<NUM>, <NUM>) having the guide edge (<NUM>) further comprises a guide shoulder (<NUM>), and wherein the guide shoulder (<NUM>) comprises a raised portion of the guide edge (<NUM>) of greater thickness than the thickness of the at least one of the first bone plate and the second bone plate (<NUM>, <NUM>) having the guide edge (<NUM>).