Patient-specific sacroiliac guides and associated methods

[0001] This application is a continuation of U.S. patent application Ser. No. 14/753,560 filed Jun. 29, 2015, which is a continuation of U.S. patent application Ser. No. 13/221,968 filed on Aug. 31, 2011 now issued as U.S. Pat. No. 9,066,734. The entire disclosures of the above applications are incorporated herein by reference.

[0002] The present teachings provide various patient-specific alignment guides for sacro-pelvic, sacroiliac and/or posterior iliac fixation. The patient-specific alignment guides facilitate more accurate placement of bone screws and other fixation devices that are used in various spinal fixation systems, such as, for example, thoracic and lumbar rod systems. The patient-specific alignment guides are designed and constructed preoperatively based on three-dimensional digital images of portions of the patient's pelvis and spine, including the ilium and the sacrum. The digital images of the patient's anatomy can be reconstructed from medical scans of the patient using commercially available CAD (Computer Aided Design) and/or other imaging software.

[0003] The present teachings provide orthopedic devices that include patient-specific alignment guides for various lumbopelvic fixation procedures. In some embodiments, the patient-specific alignment guide can be preoperatively configured for unilateral fixation, bilateral fixation, sacral fixation and/or sacroiliac fixation and combinations thereof. In some embodiments, the patient-specific alignment guide can be modular and intraoperatively convertible and reconfigurable at the discretion of the operating surgeon.

[0004] In some embodiments, the patient-specific alignment guide includes a patient-specific portion and a guiding element having a through opening. The patient-specific portion has a patient-specific surface preoperatively configured to nestingly mate as a negative of a portion of an iliac crest of a pelvis of a specific patient and mate to the iliac crest only in one position. The guiding element has a preoperatively configured orientation and location relative to the patient-specific portion for preparing a bore in the bone of the patient to direct a bone screw at the preoperatively configured orientation and location for sacroiliac fixation.

[0005] In some embodiments, the patient-specific alignment guide includes first and second patient-specific portions coupled by an arcuate bridge. The first patient-specific portion has a patient-specific surface preoperatively configured to nestingly mate to a portion of a first iliac crest of a pelvis of a specific patient and mate to the first iliac crest only in one position. The second patient-specific portion is similarly constructed for a second iliac crest of the patient. The bridge is configured to span a posterior contour of the pelvis of the patient. The patient-specific alignment guide can include first and second iliac guiding elements coupled to the corresponding first and second patient-specific portions, and first and second sacral guiding elements coupled to the bridge. Each of the first and second iliac and sacral guiding elements has a through opening and a preoperatively configured orientation and location relative to one of the first and second patient-specific portions for preparing a corresponding bore in the bone of the patient to direct a corresponding bone screw for sacroiliac fixation.

[0006] The present teachings also provide a method for lumbopelvic fixation. The method includes providing a convertible patient-specific alignment guide for a patient's pelvis and intraoperatively selecting one of unilateral fixation, iliac fixation, sacral fixation and bilateral sacroiliac fixation procedure for the patient. The convertible patient-specific alignment guide is reconfigured intraoperatively to a corresponding patient-specific alignment guide for the selected procedure. The convertible patient-specific alignment guide includes first and second patient-specific portions coupled by a bridge.

[0007] Further areas of applicability of the present teachings will become apparent from the description provided hereinafter. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present teachings.

[0027] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

[0028] The following description is merely exemplary in nature and is in no way intended to limit the present teachings, applications, or uses. For example, although some of the present teachings are illustrated for sacroiliac fixation, the present teachings can be used for any other lumbopelvic procedure or lumbar and/or pelvic correction including trauma, deformation or disease.

[0029] The present teachings provide various patient-specific alignment guides for sacro-pelvic, sacroiliac and/or posterior iliac fixation. The patient-specific alignment guides can facilitate and improve the accuracy of the placement of bone screws and other fixation devices that are used in various spinal fixation systems, such as, for example, thoracic, lumbar and lumbopelvic fixation systems.

[0030] The patient-specific alignment guides of the present teachings are designed to guide and facilitate lumbopelvic fixation and help mitigate bone screw breaches of bone or neurovascular injury that can sometimes happen during unguided implantation of a lumbopelvic fixation system. Further, unguided implantation can be complicated by the characteristic three-dimensional geometry of the sacroiliac anatomy and/or the difficulty in directing bone screws toward strong bone anchorage, especially in the presence of cortical deficiencies, such as those that can be caused by previous autograft harvest from the posterior superior iliac spine (PSIS). Additionally, the receiver element of a bone screw assembly that is configured to receive a rod of a lumbopelvic fixation system and also support a corresponding bone screw can further complicate the placement of the bone screws connected to the corresponding receiver elements. The patient-specific alignment guides of the present teachings are preoperatively configured to alleviate or reduce some of these complications for each specific patient.

[0031] The patient-specific alignment guides are designed and constructed preoperatively based on three-dimensional digital images of portions of the patient's pelvis and spine, including the ilium, iliac wings and iliac crests and the sacrum. The three-dimensional digital images of the patient's anatomy can be reconstructed preoperatively from MRI, CT, ultrasound, X-ray, or other imaging and medical scans of the patient's anatomy using computer-assisted image methods. Various CAD programs and/or software can be utilized for three-dimensional image reconstruction, such as, for example, software commercially available by Materialise USA, Plymouth, Mich.

[0032] Various pre-operative planning procedures and patient-specific alignment guides are described in commonly assigned and co-pending U.S. patent application Ser. No. 11/756,057, filed May 31, 2007, now U.S. Patent Publication No. 2007/0288030; U.S. patent application Ser. No. 12/025,414, filed Feb. 4, 2008, now U.S. Patent Publication No. 2008/0114370; U.S. patent application Ser. No. 12/103,824, filed Apr. 16, 2008, now U.S. Patent Publication No. 2008/0257363; U.S. patent application Ser. No. 12/371,096, filed Feb. 13, 2009, now U.S. Patent Publication No. 2009/0151736; U.S. patent application Ser. No. 12/483,807, filed Jun. 12, 2009, now U.S. Patent Publication No. 2009/0254367; U.S. patent application Ser. No. 12/872,663, filed Aug. 31, 2010, now U.S. Patent Publication No. 2010/0324692; U.S. patent application Ser. No. 12/973,214, filed Dec. 20, 2010, now U.S. Patent Publication No. 2011/0092804; and, U.S. patent application Ser. No. 12/978,069, filed Dec. 23, 2010, now U.S. Patent Publication No. 2011/0093086. The disclosures of the above applications are incorporated herein by reference.

[0033] In the preoperative planning stage for lumbopelvic fixation, a preoperative surgical plan is formulated for a specific patient with interactive input from the patient's surgeon or other medical professional. Imaging data of the relevant anatomy of a patient can be obtained at a medical facility or doctor's office, using any of the medical imaging methods described above. The imaging data can include, for example, various medical scans of a relevant joint portion or other relevant portion of the patient's anatomy, as needed for the particular surgical procedure. The imaging data thus obtained and other associated information can be used to construct a three-dimensional computer (digital) image of a relevant portion of the anatomy of the patient, such as, in the present application, portions of the patient's pelvis and spine, including the sacral and iliac regions. The three-dimensional digital image of the patient's anatomy can be used to formulate a preoperative surgical plan specific to the patient. The preoperative surgical plan can include the design and construction of implants, patient-specific alignment guides and other instruments according to selected methods of surgical preparation and implantation. The preoperative surgical plan can also include planning for the location and orientation of bone modifications and/or resections and trajectory paths for various implant components, including, for example bone screws.

[0034] Generally, the patient-specific alignment guides of the present teachings are configured to match portions of the iliac and/or sacral anatomy of a specific patient and are generally designed and configured using computer modeling based on the reconstructed three-dimensional digital image of the patient's corresponding anatomy, as discussed above. The patient-specific alignment guides have a patient-specific anatomy-engaging surface that is configured as a mirror or negative or complementary surface that can conformingly contact and match a corresponding bone surface of the patient (with or without cartilage or other soft tissue). In this respect, a patient-specific alignment guide can register to and nestingly mate with the corresponding bone surface, such as, for example, a portion of the iliac crest, of the specific patient in only one position. The patient-specific alignment guides of the present teachings can be configured for use in any surgical procedure, such as open, mini-open and minimally invasive procedure.

[0035] The three-dimensional model of the patient's anatomy can be viewed on a computer display or other electronic screen and can also be reproduced as a hard copy on film or other medium and viewed by direct or indirect or backlight illumination. The model can be sized for viewing on any appropriate screen size and may be cropped, rotated, etc., as selected by the individual (e.g., the surgeon) viewing the screen.

[0036] The patient-specific alignment guides can be manufactured by rapid prototyping methods, such as stereolithography or other similar methods, or by CNC milling, or other automated or computer-controlled machining or robotic methods. The patient-specific alignment guides can be manufactured from any biocompatible materials, including metals, polymers and combinations thereof. The patient-specific alignment guides, the implants for the surgical procedure and, optionally, other disposable instruments can be sterilized, packaged and forwarded to the surgeon or the surgeon's medical facility for the surgical procedure.

[0037] As a brief overview, and referring to FIGS. 1-13, prior art spinal fixation systems are briefly described in reference to FIGS. 1-3. Various embodiments of patient-specific alignment guides are described in reference to FIGS. 4-8. For example, FIG. 6 illustrates a patient-specific “iliac” guide 100A for inserting fixation screws starting from and into the ilium of the patient, according to the present teachings. FIG. 7 illustrates a patient-specific “sacral” guide 100B for inserting fixation screws from the sacrum and into the ilium, according to the present teachings. FIGS. 4, 5 and 5A illustrate “universal” patient-specific guides 100, 100′ for inserting bilaterally or unilaterally fixation screws from and into the ilium and/or from the sacrum and into the ilium according to the present teachings. FIG. 8 illustrates a patient-specific unilateral iliac guide 1000 for inserting fixation screws into the left ilium according to the present teachings. FIG. 9 illustrates screw bores prepared in the bone using an alignment guide of the present teachings and shown after the alignment guide is removed. Post implantation details of the lumbopelvic fixation system implanted using the bores pre-drilled with the alignment guides of the present teachings are shown in FIGS. 8-13.

[0038] Referring to FIGS. 1-3, portions of prior art spinal fixation systems (or rod systems) are illustrated. Various spinal and/or lumbopelvic fixation systems are commercially available from Biomet Manufacturing Corp., Warsaw, Ind., and include, for example, the Polaris® fixation system and the Array® system. An exemplary spinal fixation system 50 can include elongated fixation members or rods 52 that can be attached to the patient's anatomy with bone screw assemblies 60 inserted into thoracic pedicles, lumbar pedicles 45, sacrum 40 and/or iliac wings 30 or iliac crest 32 of a patient's pelvis depending on the surgical technique and the corrective procedure selected for the patient. The bone screw assembly 60 can include a bone screw 62 with a bone anchoring portion inserted into the bone, a U-shaped (“tulip”) receiver 64, and a securing cap 66. The receiver 64 is configured to receive or support the head of the bone screw 62 and optionally allow multi-axial pivoting of the bone screw 62. The receiver 64 is also configured to transversely hold the rod 52. The securing cap 66 is received and/or engaged to the receiver 64 and locks the rod 52 and the bone screw 62. In other embodiments, the bone screw assembly 60 can include fixed, rather than polyaxial, bone screws.

[0039] With continued reference to FIGS. 1-3, cross-connectors 70 between two rods 52 can be used to provide additional stability to the spinal fixation system 50 along the spine. Further, lateral connectors 76 can be used to provide iliac fixation and extend the spinal fixation system 50 over the iliac wings, as shown in FIG. 1. The lateral connector 76 shown in FIG. 1 includes, for example, a receiver portion 75 coupled to the rod 52 and an elongated shaft 78 coupled to a bone screw assembly 60 that is positioned through the iliac crest 32. Exemplary embodiments of the spinal fixation system 50 and associated instruments and implants, including the bone screw assembly 60 with the optional cross connectors 70 and lateral connectors 76 are commercially available from Biomet Manufacturing Corp., Warsaw, Ind. It will be appreciated, however, that other spinal fixation systems can be used according to the present teachings including, for example, the spinal fixation systems, bone screw assemblies, cross connectors and lateral connectors described in U.S. Pat. Nos. 7,294,129, 6,302,888, 6,616,668 and 7,699,876, the disclosures of which are incorporated herein by reference.

[0040] Referring to FIGS. 4-5A, 9 and 10, two embodiments of a universal patient-specific sacroiliac alignment guide 100, 100′ (“the universal guide” for short) are illustrated. The universal guide 100, 100′ is preoperatively configured to guide the drilling of one or more “iliac” (starting at the iliac wing or iliac crest) bores 150, 152 and one or more “sacral” (starting at the sacrum) bores 154 (see FIG. 9) to implant corresponding iliac and sacral bone screws 61, 63, 65 for a spinal fixation system 50 (see FIG. 10). As can be seen in FIG. 9, the iliac bores 150, 152 are initiated from an iliac crest 32 and are directed into an iliac wing 30. The sacral bores 154 initiated from the sacrum 40 and are also directed into the iliac wing 30 through a corresponding sacroiliac joint. The two embodiments of the universal guide 100, 100′ have many similar elements and will be commonly described, except as noted to highlight any differences. Each universal guide 100, 100′ can include first and second patient-specific portions 102 (right 102R, left 102L) that can be either integrally (monolithically) or modularly (removably) connected to one another by an elongated curved or arcuate connector or bridge 104. The bridge 104 can include a tab portion 106 with a through hole 108 for receiving a locating pin 140 (K-wire or other type of pin) referencing the first sacral process (S1) of the spine, as shown in FIGS. 5 and 9. The locating pin 140 can be used to confirm the accurate placement of the universal guide 100, 100 by intraoperatively trialed to confirm contact with the S1 sacral process. The locating pin 140 can also be used for other anatomic landmarks, such as one or more sacral or spinous processes. The arcuate shape of the bridge 104 generally follows the contour of the posterior surface of the pelvis and can facilitate an effortless placement of the universal guide 100, 100′ on the specified anatomy. The bridge 104 can also function as a handle for holding or guiding the universal guide 100, 100′ on the pelvis. The bridge 104 can be removably coupled to each patient-specific portion 102 by a taper-to-taper or other releasable connection, as shown in the exemplary illustration of FIG. 4A.

[0041] With continued reference to FIGS. 4-5A, 9 and 10, each patient-specific portion 102 is preoperatively configured from a three-dimensional image of the pelvis of the patient that is reconstructed from medical scans of the patient, as discussed above. Specifically, the patient-specific portion 102 has a patient-specific surface 103 configured as a negative or mirror of a portion of the iliac crest 32 and, optionally, adjacent areas. The patient-specific surface 103 tracks the unique anatomy of the specific patient's iliac crest 32 that provides natural referencing landmarks. Accordingly, the patient-specific portion 102 can be positioned intraoperatively with accuracy, and without our intraoperative guidance, in a preoperative determined single location of the iliac crest 32. The patient-specific portion 102 nests and nestingly mates to the corresponding iliac crest 32, as shown in FIGS. 5 and 5A. In some embodiments, the patient-specific portion 102 can snap onto the corresponding iliac crest 32.

[0042] Each patient-specific portion 102 includes one or more “iliac” guiding elements 122, 124 with corresponding openings 123, 125 passing through the patient-specific portion 102 for guiding a drill or other cutting instrument and forming corresponding iliac bores 150, 152 from the iliac crest 32 through the iliac wing 30. The iliac guiding elements 122, 124 are configured preoperatively with patient-specific orientations and locations. The openings 123, 125 of the iliac guiding elements 122, 124 can be tapered and sized to receive a drill bit either directly or indirectly by receiving a sleeve or other drill guide to stabilize and guide a drill. In other embodiments, the openings 123, 125 can be cylindrical to limit space requirements. In some embodiments, a metal sleeve may be press-fitted into a corresponding opening 123, 125 to provide additional rigidity and stability, especially when the universal guide 100, 100′ (or any of the patient-specific alignment guides) is made of polymer or other plastic.

[0043] In some embodiments, a drill guide can be used to guide a drill, such as the drill guide 200 shown in FIGS. 4C and 4D. The drill guide 200 can have a space-saving cylindrical shaft 202 with a cylindrical bore 208 and can be configured to be received into a corresponding opening 123, 125 of a corresponding iliac element 122, 124. Each drill guide 200 can be marked with color-coded and/or raised or embossed marking (e.g., X.Xmm) indicating the size of the corresponding guiding element 122, 124 with which it can be used. The marking 210 can be placed on an outer surface of a block element 204 that is connected to the shaft 202. The block element 204 can be used as a handle and can include grooves 206 or other tactile or frictional formations for facilitating secure hand gripping. The block element 204 can be offset relative to the shaft 202 in a direction that avoids interfering with visualization during the surgical procedure.

[0044] Similarly, the guiding elements 122, 124 can be identified with color-coding and/or raised markings indicating size. Embossed or raised markings 113 can also be provided on the bridge 104 to indicate caudal and cephalad directions for the placement of the universal guide 100, 100′ (and the other patient-specific alignment guides of the present teachings).

[0045] With continued reference to FIGS. 4-5A, 9 and 10, the universal guide 100, 100′ can include one or more elongated arms 132 extending from the bridge 104 toward the sacrum 40 (left and right arms 132 are illustrated). In some embodiments, the arm 104 can extend from the patient-specific portion 102, rather than from the bridge 104. In some embodiments, the arm 132 can be removably coupled to the patient-specific portion 102 or the bridge 104 by a quick-connect/disconnect coupling, such as snap-fit, tongue and groove, taper-to-taper, etc., as shown in an exemplary illustration of FIG. 4A. Each arm 132 can support one (or more) sacral guiding elements 130 having corresponding openings 131. The arm 132 can be curved and oriented such that the sacral guiding element 130 is positioned in a preoperatively determined position and orientation for the specific patient based on the preoperative plan for the patient. The opening 131 of the sacral guiding element 130 can be tapered and sized to receive a drill bit or a sleeve (not shown) for stabilizing and guiding a drill. The sacral guiding element 130 is configured preoperatively with patient-specific orientation and location for guiding a sacral bone screw 65 through a bore 154 drilled from the sacrum 40 into the iliac wing 30 of the patient, as shown in FIGS. 9 and 10. Additionally, the orientations and positions of the iliac guiding elements 122, 124 and sacral guiding elements 130 are configured to avoid interference among the trajectories of the corresponding bone screws and provide anchoring in non-deficient cortical bone. In some embodiments, placement of the bone screws at patient-specific distances from the sciatic notch is preoperatively configured by the arrangement of the iliac and sacral guiding elements 122, 124, 130. Further, in some embodiments, all or some of the iliac and/or sacral guiding elements 122, 124, 130 can be modular or removable and couplable to the corresponding patient-specific portions 102 with taper-to-taper connections, bayonet connections, threadable connections, snap-fit connections or other removable or releasable connections, as illustrated in FIG. 4B. The iliac sacral guiding elements 122, 124, 130 can be color-coded and marked for size with raised or embossed markings, as discussed above.

[0046] Each of the patient-specific portions 102 can also include a fixation guiding element 120 with a corresponding opening 121 for guiding a temporary fixation guiding element such as a trocar pin or the pin 140 shown in FIG. 6A for temporarily attaching the universal guide 100, 100′ on the pelvis of the patient. The opening 121 of the fixation guiding element 120 can be smaller in diameter than the openings 123, 125 and 131 of the corresponding iliac and sacral guiding elements 122, 124 and 130 that are used for drilling bores for the bone screws 62 of the iliac and sacral screw assemblies, as shown in FIG. 9. The fixation guiding element 120 is shown as located cephaladly (superiorly) on the patient-specific portion 102 of the universal guide 100 in FIGS. 4 and 5, and caudally (inferiorly) on the patient-specific portion 102 of the universal guide 100′ shown in FIG. 5A. In some embodiments, the patient-specific portion 102 of the universal guide 100′ can extend further caudally along the iliac crest 32, and the bridge 104 of the universal guide 100′ can extend from a position cephalad to the fixation guiding element 120, as shown in FIG. 5A. The locations of the temporary fixation pins 140 that are used to support the universal alignment guide 100 on the pelvis are shown at 157 in FIG. 9.

[0047] Referring to FIGS. 9-13, after the iliac and sacral bores 150, 152, 154 have been formed using the universal guide 100, 100′, the universal guide 100, 100′ is removed from the pelvis and preoperatively selected and determined portions 37 of the iliac crests 32 can be resected to create a planar recess or seat 38 to accommodate the receivers 64 of the first and second iliac screw assemblies 61, 63 shown in FIGS. 11-13.

[0048] Referring to FIGS. 6-8, the iliac guide 100A, sacral guide 100B and unilateral guide 100C are more specialized versions of the universal guide 100, 100′. The iliac guide 100A, as shown in FIG. 6, is similar to the universal guide 100 shown in FIG. 5, but with the sacral guiding elements 130 omitted. It will be appreciated, however, that in other embodiments, the iliac guide 100A can be arranged as the universal guide 100′ shown in FIG. 5A, but with the sacral guiding elements 130 omitted.

[0049] The sacral guide 100B, as shown in FIG. 7, is similar to the universal guide 100 shown in FIG. 5, but with the iliac guiding elements 122, 124 omitted. It will be appreciated, however, that in other embodiments, the sacral guide 100B can be arranged as the universal guide 100′ shown in FIG. 5A, but with the iliac guiding elements 122, 124 omitted.

[0050] The unilateral guide 100C, as shown in FIG. 8, is similar to the one side (left side is shown) of the universal guide 100′ shown in FIG. 5A, without the bridge 104 and without the sacral guiding element 130. It will be appreciated, however, that in other embodiments, the unilateral guide 100C can be arranged as the universal guide 100 shown in FIG. 5, without the bridge 104 and without the sacral element 130. The unilateral guide 1000, as shown in FIG. 8, is a left side iliac unilateral guide. A right side iliac unilateral guide can be similarly constructed. Additionally, unilateral (left or right side) sacral guides can be constructed by using the arrangement of the sacral guide 100B shown in FIG. 7 without the bridge 104 and without the opposite side patient-specific portion 102.

[0051] Although various separate patient-specific unilateral, iliac and sacral can be constructed for a specific patient and surgeon, the patient-specific universal guide 100, 100′ forms a bilateral sacroiliac guide that can be utilized intraoperatively to cover any intraoperative change in plan or intraoperative event for the specific patient. For example, if the surgeon decides to only do a unilateral fixation using sacral and/or iliac bone screws on the left (right) side only, then the corresponding iliac and/or sacral guiding elements of the opposite right (left) side can simply not be used (no drilling on that side). In this respect, removable plugs or covers can be provided in all or some of the guiding elements, such that attention is directed to which guiding elements should be used by positively removing the plugs and exposing the corresponding guiding openings.

[0052] Another option is to decouple the bridge 104 and the right (left) side of the universal guide 100, 100′ from the left (right) side and completely remove it. Similarly, the universal guide 100, 100′ can be used for iliac fixation only or for sacral fixation only by not using or by removing those iliac or sacral guiding elements that are not needed. Additionally, the universal guide 100, 100′ can be fully modular, as described above, and constructed as a bilateral sacroiliac guide with a removable bridge 104 and removable iliac and sacral guiding elements 122, 124, 130 and/or arms 132. The modular universal guide 100, 100′ is intraoperatively convertible and reconfigurable at the discretion of the operating surgeon. Accordingly, the same universal patient-specific guide 100, 100′ can be used in several different fixation options of the same patient. As these fixation options are changed or selected intraoperatively, the modular universal guide 100, 100′ provides the surgeon with intraoperative flexibility, reconfigurability and adaptability to an intraoperative change of plan and surgical procedure informed by intraoperative and possibly unanticipated circumstances. Color-coding and raised or embossed markings indicating size, orientation or other relevant information, such as, for example, patient identification, guide or element type and position, can help streamline intraoperative assembling, positioning and use and help avoid errors. At the same time, and regardless of the fixation option selected, the features and advantages of using a patient-specific guide are retained.

[0053] The universal guide 100, 100′ (or the iliac guide 100A, or the sacral guide 100B, or the unilateral guide 100C) is removed from the pelvis after the bone bores (150, 152, 154) for the selected fixation procedure have been drilled into the bone. The bone bores (150, 152, 154) are used to guide corresponding bone screw assemblies of a selected fixation system 50 according to the surgical technique associated with the fixation system.

[0054] Example embodiments are provided so that this disclosure is thorough, and fully conveys the scope to those who are skilled in the art. Numerous specific details are set forth, such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure.

[0055] It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Accordingly, individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.