Patient-Specific Acetabular Guide For Anterior Approach

[0001] The present teachings relate to patient-specific acetabular guides and associated instruments for hip joint arthroplasty.

[0002] The present teachings provide a patient-specific acetabular guide and associated instruments for implanting an acetabular implant into an acetabulum of a patient for hip joint arthroplasty.

[0003] The present teachings provide various instruments and methods for generally preparing the acetabulum of a patient to receive an acetabular implant, such as, for example, an acetabular cup along an alignment axis. The alignment axis and various patient-specific guides and other associated instruments can be designed during a pre-operative plan using a three-dimensional reconstruction of the patient's relevant anatomy, such as the pelvis or portions thereof, including the acetabular and periacetabular areas of the pelvis. The three-dimensional reconstruction can be based on medical images, including MRI, CT, ultrasound, or X-ray scans and prepared using commercially available imaging software.

[0004] The present teachings provide, for example, a patient-specific acetabular guide that can be used for preparing an acetabulum of a patient to receive an acetabular implant, such as an acetabular cup. The acetabular guide has a dome-shaped body with a peripheral annular rim and an outer three-dimensional surface configured to match an acetabulum of a specific patient's hip joint from three-dimensional medical images of the patient's hip joint during a preoperative plan for the patient. A patient-specific registration guide can be permanently or removably attached to the peripheral rim. The patient-specific registration guide has a longitudinal bore defining a patient-specific alignment axis with an alignment orientation configured for guiding an acetabular implant for the patient during the preoperative plan of the patient. The registration guide has a patient-specific undersurface configured to mate with a corresponding portion of a periacetabular surface and/or acetabular rim surface of the acetabulum of the patient.

[0005] In some embodiments, the acetabular guide can include a plurality of spaced-apart registration hooks. Each registration hook can extend from and be attached to the peripheral rim of the acetabular guide. Each registration hook has a patient-specific undersurface configured to mate with a corresponding surface of the acetabular rim of the patient's acetabulum.

[0006] The present teachings also provide a method for hip joint arthroplasty. The method includes inserting a patient-specific acetabular guide into an acetabulum of a patient. A patient specific undersurface of a dome-shaped body of the acetabular guide mates substantially as negative of a corresponding surface of the acetabulum. At least one patient-specific registration hook extends from a peripheral rim of the acetabular guide over a portion of an acetabular rim of the acetabulum. The method includes inserting an alignment pin into the patient's bone through a bore of a patient-specific registration guide. The patient-specific registration guide is removably attached to the peripheral rim of the acetabular guide. The patient-specific registration guide is preoperatively configured to define a patient-specific alignment orientation for inserting an acetabular implant. The method includes removing the acetabular guide without removing the alignment pin and inserting an acetabular implant along an orientation parallel to the alignment pin.

[0007] In some embodiments, the acetabular guide can be inserted into the acetabulum using an inserter with a removable adapter element. A distal bore of the adapter element can be coupled to a first post of the acetabular guide. A second post of the acetabular guide can held between first and second flanges extending from the adapter element.

[0008] 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.

[0023] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

[0024] The following description is merely exemplary in nature and is in no way intended to limit the present teachings, applications, or uses.

[0025] The present teachings generally provide patient-specific acetabular alignment guides, inserters and/or other associated instruments for use in orthopedic surgery, such as, for example, in joint replacement or revision surgery for the hip. The patient-specific alignment guides and associated instruments can be used either with conventional or with patient-specific implant components prepared with computer-assisted imaging methods based on medical scan of the specific patient.

[0026] As described in commonly assigned U.S. Pat. No. 8,092,465, issued Jan. 1, 2012, and co-pending U.S. patent application Ser. No. 13/400,652, filed Feb. 21, 2012, both of which are incorporated by reference herein, during a preoperative planning stage, imaging data of the relevant anatomy of a patient can be obtained at a medical facility or doctor's office. The imaging data can include, for example, a detailed scan of a pelvis, hip, knee, ankle or other joint or relevant portion of the patient's anatomy. The imaging data can be obtained using an MRI, CT, and X-Ray, ultrasound or any other imaging systems. The imaging data obtained can be used to construct a three-dimensional computer image of the joint or other portion of the anatomy of the patient and prepare an initial preoperative plan that can include bone or joint preparation, such as planning for resections, milling, reaming, broaching, as well as implant selection and fitting, design of patient-specific guides, templates, tools and alignment protocols for the surgical procedure. Additionally, physical modes of the patient's joint and associated bones can be prepared for visualization and trialing of the guides and implants prior to the surgical procedure.

[0027] Computer modeling for obtaining three-dimensional computer images of the relevant patient's anatomy can be provided by various CAD programs, applications and/or software commercially available from various vendors or developers, such as, for example, from by Object Research Systems or ORS, Montreal, Canada. The computer modeling program or other application can be configured and used to plan a preoperative surgical plan, including planning various bone preparation procedures, to select or design/modify implants and design patient-specific guides and tools including patient-specific prosthesis components, and patient-specific tools, including reaming, broaching, milling, drilling or cutting tools, alignment guides, templates and other patient-specific instruments.

[0028] The preoperative plan can be stored in any computer storage medium, in a computer file form or any other computer or digital representation, including three-dimensional graphical files or digital data sets. The preoperative plan, in a digital form associated with interactive software or other application, can be made available via a hard medium, a web-based or mobile or cloud service, or a cellular portable device to the surgeon or other medical practitioner, for review. Using the interactive software or application, the surgeon can review the plan, and manipulate the position of images of various implant components relative to an image of the anatomy. The surgeon can modify the plan and send it to the manufacturer with recommendations or changes. The interactive review process can be repeated until a final, approved plan, is sent to a manufacturing facility for preparing the actual physical components. In other embodiments, physical and digital patient-specific bone models guides and instruments and can be provided preoperatively to the surgeon for trialing and marking.

[0029] After the surgical plan is approved by the surgeon, patient-specific implants and associated tools, including, for example, alignment guides, cutting/milling/reaming/broaching or other tools for the surgical preparation of the joint or other anatomy portion of the specific patient can be designed using a CAD program or other three-dimensional modeling software, such as the software provided by Object Research Systems or ORS, Montreal, Canada, for example, according to the preoperative surgical plan. Patient-specific guides and other instruments can be manufactured by various stereolithography methods, selective laser sintering, fused deposition modeling or other rapid prototyping methods. In some embodiments, computer instructions of tool paths for machining the patient-specific guides and/or implants can be generated and stored in a tool path data file. The tool path data can be provided as input to a CNC mill or other automated machining system, and the tools and implants can be machined from polymer, ceramic, metal or other suitable material depending on the use, and sterilized. The sterilized tools and implants can be shipped to the surgeon or medical facility for use during the surgical procedure.

[0030] Patient-specific implants, guides, templates, tools or portions thereof are defined herein as those constructed by a preoperative plan for a specific patient from three-dimensional images of the specific patient's anatomy reconstructed from preoperative medical scans of the patient. The patient-specific components are constructed to closely conform and mate or match substantially as a negative mold or negative surface or inverse or mirror surface of corresponding surface portions of the patient's anatomy, including bone surfaces with or without associated soft tissue, such as articular cartilage, for example, depending on the particular procedure, implant and tool use. Minute irregularities of the patient's joint surfaces need not be mirrored.

[0031] As discussed above, patient-specific alignment guides and implants are generally configured to match the anatomy of a specific patient and can fit in only one position on a corresponding surface of the specific patient because anatomic features that are unique to each patient can function as landmarks and can guide placement of the alignment guide or implant in only one position without the need of intraoperative navigation, patient marking or other intraoperative guidance. The patient-specific alignment guides are generally configured and manufactured using computer modeling based on the patient's 3-D anatomic image and have an engagement surface that is made to conformingly contact and match as a mirror or negative or inverse surface to a corresponding surface of a three-dimensional image/model of the patient's bone surface (with or without cartilage or other soft tissue), by the computer methods discussed above. Generally, the patient specific guide has an exterior surface that contacts about 80% of the patient's anatomy when properly positioned, including about 90%, and about 98%. The exterior surface of the patient matched guide can, therefore, substantially mate with the selected portion of the anatomy. It is understood, however, that certain exterior portions of a patient specific guide may not have substantial contact with the patient, while other portions are designed to ensure contact even when other portions are not contacting the patient. Thus, a patient matched guide can have portions that are substantially patient matched and have or can achieve the selected amount of contact with the patient.

[0032] The patient-specific alignment guides can include one or more custom-made guiding formations, such as, for example, guiding bores or cannulated guiding posts or cannulated guiding extensions or receptacles that can be used for supporting or guiding other instruments, such as drill guides, reamers, cutters, cutting guides and cutting blocks or for inserting pins or other fasteners according to a surgeon-approved pre-operative plan. The patient-specific alignment guides can be used in minimally invasive surgery, and also in surgery with multiple minimally-invasive incisions. Various alignment guides and pre-operative planning procedures are disclosed in commonly assigned U.S. Pat. No. 8,092,465, issued Jan. 10, 2012; U.S. Pat. No. 8,070,752, issued Dec. 6, 2011; U.S. Pat. No. 8,133,234, issued Mar. 13, 2012; co-pending U.S. patent application Ser. No. 12/211,407, filed Sep. 16, 2008; co-pending U.S. patent application Ser. No. 12/025,414, filed Feb. 4, 2008; co-pending Ser. No. 13/111,007, filed May 19, 2011; co-pending U.S. patent application Ser. No. 13/041,469, filed Mar. 7, 2011; and co-pending U.S. patent application Ser. No. 13/400,652, filed Feb. 21, 2012. The disclosures of the above patents and applications are incorporated herein by reference.

[0033] Referring to FIGS. 1A-9, the present teachings provide a patient-specific acetabular guide 100 and an acetabular guide inserter 300 an adapter element 350. As discussed herein, the adapter element may or may not be removable from a handle portion during operation. The acetabular guide 100 can be used in connection with various other instruments to generally provide a patient-specific alignment axis A. The patient-specific alignment axis A is used to insert an alignment pin 230 and generally to orient, insert, and implant an acetabular implant or acetabular cup 250 in an acetabulum (or acetabulum cavity) 82 of the patient, to facilitate guided reaming of the acetabulum 82, and generally guide any instruments and procedures relative to the alignment axis A or the alignment pin 230. The alignment axis A is determined during the preoperative plan from the three-dimensional image of the hip joint of the patient as the axis along which the acetabular implant 250 is to be centered and inserted. The alignment axis A is generally perpendicular the acetabulum 82 and corresponding acetabular engagement surface 252 of the acetabular implant 250. More specifically, with reference to FIG. 2B, the orientation (i.e., angles) of the alignment axis A can be selected and specified relative the axial plane (AP), sagittal plane (SP) and anterior pelvic plane (APP). The coronal plane is a vertical plane that is orthogonal to the axial and sagittal planes (not shown). The anterior pelvic plane (APP) is defined as a plane passing through the two anterior iliac spines and the pubic symphysis of the pelvis 80 of the patient. The APP may deviate from being parallel to the coronal plane when viewed in the weight-bearing profile of the patient (standing). Additionally, the APP plane may have a different orientation in the supine position. The deviation varies from patient to patient, such that the anterior pelvic plane cannot be relied on by the surgeon without additional information to guide the acetabular implant and avoid impingement during motion. The angle between the anterior pelvic plane and the coronal plane can be referenced as a pelvic tilt and is zero when the anterior pelvic plane is parallel to the coronal plane. The present teachings determine a patient-specific axis for inserting an acetabular implant. The patient-specific alignment axis is physically and uniquely identified by the orientation of an alignment pin inserted into the bone using the patient-specific acetabular guide and landmark registration incorporated into the acetabular guide during the preoperative plan. Specifically, the preoperative plan that is based on images of the hip joint of the patient can accurately determine the orientation of the alignment axis A and fix it intraoperatively via the patient-specific acetabular guide 100 on the pelvis 80 of the patient to guide the surgeon during the surgical procedure.

[0034] The patient-specific acetabular guide 100 can engage the acetabulum 82 of the specific patient in a unique (only one) position and can provide an accurate alignment axis A relative to the planned orientation of the acetabular implant 250. The patient-specific acetabular guide 100 can also provide secure fitting and rotational stability in a design that is lightweight and has compact size and small bulk.

[0035] FIGS. 1A-3 illustrate a patient-specific acetabular guide 100 that has a dome-shaped body 102 with a three dimensional patient-specific undersurface or outer surface 104 configured to contact and engage the acetabulum 82. The outer surface 104 is designed and/or formed to match as a negative of a corresponding surface of the acetabulum 82 from the three-dimensional image of the patient's hip joint. Thus, the outer surface 104 is formed to mate closely, such as to contact about 85% to about 100% of the acetabulum 82 when positioned in the acetabulum 82.

[0036] The dome-shaped body 102 of the patient-specific acetabular guide 100 can have one or more openings in the form of windows 106 that reduce the weight of the patient-specific acetabular guide 100 and provide improved visualization of the underlying anatomy. The dome-shaped body 102 can also include additional holes or other apertures 109 for drilling holes in the acetabulum 82 and corresponding to holes 254 for fixation screws of the acetabular implant 250. The dome-shaped body 102 of the patient-specific acetabular guide 100 is bounded by a guide rim 108 in the form of a closed-contour peripheral annular surface that has an uneven, irregular, jagged or wavy shape that follows the corresponding irregular shape of an acetabular rim 84 (and periacetabular surface) around the acetabulum 82 of the patient. Additionally, the patient-specific acetabular guide 100 can include one or more registration hooks or extensions 110 that extend from the guide rim 108 along a three-dimensional curved surface around the acetabular rim 84 at different and spaced-apart positions. The registration hooks 110 are configured to provide additional registration locations for the patient-specific acetabular guide 100 by replicating corresponding underlying surface portions or landmarks of the acetabular rim 84 in a patient-specific manner. Specifically, each registration hook 110 can have a curved (three-dimensional) undersurface 112 that is patient-specific and negative of the surface of the acetabular rim 84 at specific locations selected as landmark locations during the preoperative plan for the patient. Each registration hook 110 can include a hole 114 for receiving a fixation pin or other fixation element 116 (shown in FIG. 4) for attaching the patient-specific acetabular guide 100 to the pelvis of the patient.

[0037] The patient-specific acetabular guide 100 can include a removable or non-removable registration and alignment guide 120 (referenced as registration guide 120, for short) that has a longitudinal bore 124 along the patient-specific alignment orientation A. A removable drill insert 122 with a longitudinal bore 126 can be received concentrically in the bore 124 of the registration guide 120. The wall of the bore 124 of the registration guide 120 can define a taper that engages a complementary taper 127 of an end of the removable drill insert 122. The complementary tapers can ensure appropriate and selected alignment of the bore 124 and the insert bore 126. Thus, the bore 124 and the insert bore 126 can be concentric and coextensive.

[0038] The drill insert 122 can provide stability during the insertion of an alignment pin 230 that can define the alignment axis A. The alignment pin 230 can include a drill tip 231 that can drill into the bone of or near the acetabulum. The alignment pin 230 is received into the concentric and coextensive bores 124, 126 of the registration guide 120 and of the drill insert 122. Accordingly, the alignment pin 230 is oriented along the alignment axis A. The drill insert 122 can be formed of a tough and/or strong material. For example, the drill insert 122 can be metallic and reusable, while the registration guide 120 and the acetabular guide 100 are patient-specific and can be made of a softer material, such as a polymer material, and can be disposable. The tough material of the drill insert 122 can engage the alignment pin 230 without deformation and protect the registration guide 120 from damage due to engaging the alignment pin 230.

[0039] The registration guide 120 has an undersurface portion that is a patient-specific undersurface 128 that can hook around or snap-on or otherwise engage and contact the guide rim 108 at a pre-defined marked location determined during the preoperative plan of the patient. The registration guide 120 that includes the patient-specific undersurface 128 matches the surface of the acetabular rim 84 and/or periacetabular area of the pelvis 80 of the patient at a corresponding location. The bore 124 of the registration guide 120 and the bore 126 of the drill insert 122 can have an open (i.e., non-continuous) periphery defining a longitudinal slit 133 that is configured to allow the patient-specific acetabular guide 100 to be removed from the pelvis of the patient without removing the alignment pin 230 that is inserted into the pelvis 80 and defines the alignment axis A. In other words, the patient-specific acetabular guide 100 can be also removed by side or lateral motion relative to the slit 133 and the longitudinal axis A and not necessarily by only motion along the alignment axis A or along the alignment pin 230.

[0040] The patient-specific acetabular guide 100 can include first and second posts 130, 132 extending from an interior surface 105 (opposite to outer surface 104) of the dome-shaped body 102 of the patient-specific acetabular guide 100. The first post 130 can be tubular and can define a bore 134 that passes through the dome-shaped body 102 of the acetabular guide for optional fixation to the acetabulum 82 using a pin or other fastener. The bore 134 is not necessary, however, and the post 130 can be a closed hollow post or a solid post. The first post 130 can be centrally located and perpendicular relative to the dome-shaped body 102 of the patient-specific acetabular guide 100 and the underlying surface of the acetabulum 82. The second post 132 can be offset relative to the first post 130 along a radial direction relative to the periphery of the guide rim 108. The second post 132 can be shorter in height relative to the first post 130. The posts 130, 132 can be used to insert the patient-specific acetabular guide 100 using an acetabular guide inserter, such as the acetabular guide inserter 300 shown in FIG. 8.

[0041] It should be noted that other inserters can also be used to connect to one or both posts 130, 132 and be coupled to the patient-specific acetabular guide 100. According to various embodiments, the acetabular guide inserter 300 can be modular and include an elongated portion 302 and the adapter element (or inserter tip) 350 can be removable from the elongated portion 302. The elongated portion 302 can include a handle portion 308 and a shaft 304 having a distal post or boss 306. The adapter element 350 includes a tubular post 352 with a first bore 354 configured to connect and receive the boss 306 of the elongated portion 302 of the acetabular guide inserter 300. The elongated portion 302 can be interconnected to the adapter 350 at an appropriate time to insert the guide 100 (e.g. after the adapter 350 has engaged the post 130). It is understood, however, that the adapter can be manufactured to be fixed to the elongated portion 302 for use. For example, the elongated portion 302 and the adapter 350 can be formed as one piece or fixed together, such as with welding or an adhesive. Accordingly, it is understood that the inserter 300 need not be separable for use by a user.

[0042] The adapter element 350 includes a second bore 355 opposite to the first bore 354 and configured to receive the first tubular post 130 of the acetabular guide 100. The adapter element 350 includes first and second arms or flanges 356, 358 extending from a distal end of the adapter element 350 opposite to the post 352 and around the second bore 355. The first and second flanges 356, 358 define an open channel or a U-shaped inner surface 360 that can receive and hold the second post 132. The first and second flanges 356, 358 can be resiliently coupled to adapter element 350 and can be configured to snap-on to the second post 132 of the patient-specific acetabular guide 100 while the first post 130 of the acetabular guide 100 is received in the second bore 355 of the adapter element 350, as shown in FIGS. 3, 4 and 10.

[0043] The patient-specific acetabular guide 100 can be inserted in the acetabulum 82 using the inserter 300, as shown in FIG. 9. The inserter 300 can be removed, and the patient-specific acetabular guide 100 can be stabilized to the bone with fixation pins 232. A hole can be drilled through the drill insert 122 into the bone and the alignment pin 230 can be inserted along the alignment axis A defined by the registration guide 120. It is understood, that inserting the alignment pin 230 need not be a two-step process. For example, the alignment pin 230 can include a drill tip or portion 231 such that the alignment pin 230 is directly drilled into the bone.

[0044] Other holes can also be drilled into the bone through the holes 109 of the patient-specific acetabular guide 100 for attaching the acetabular implant 250. The fixation pins 232 can be removed and then the patient-specific acetabular guide 100 can be removed sideways without removing the alignment pin 230 and without disturbing its orientation along the alignment axis A. The acetabular implant 250 can be inserted in the acetabulum along an axis A′ parallel to the alignment axis A defined by the alignment pin 230 that is still attached to the bone. Additionally, reaming or other acetabular bone preparations can be performed using the orientation defined by the alignment pin 230 prior to the insertion of the acetabular implant 250.

[0045] The patient-specific acetabular guide 100 does not require the use of additional secondary guides to provide an alignment orientation for inserting an acetabular implant 250 or guiding other instruments. As such, the patient-specific acetabular guide 100 can be conveniently used in hip arthroplasty with an anterior supine incision along a patient-specific alignment axis A. The alignment axis A is preoperatively determined and transferred to the pelvis 80 using an alignment pin 230 guided by the registration guide 120 of the patient-specific acetabular guide 100, as discussed above.

[0046] Various patient-specific guides, secondary guides, reamers, guide handles, inserters, impactors, support devices, electronic positioners and other instruments can be used in various combinations and based on surgeon preferences or patient and preoperative or intraoperative circumstances for preparing an acetabulum and guiding and implanting an acetabular implant along a preoperatively determined alignment orientation. In this respect, tools and instrumentation providing redundant functionality and of different embodiments may provide to the surgeon in a kit or per surgeon's request.

[0047] For example, adaptors and other instruments described above can be provided and used in various combinations within the scope of the methods described herein.

[0048] The foregoing discussion discloses and describes merely exemplary arrangements of the present teachings. Furthermore, the mixing and matching of features, elements and/or functions between various embodiments is expressly contemplated herein, so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise above. Moreover, many modifications may be made to adapt a particular situation or material to the present teachings without departing from the essential scope thereof. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the present teachings as defined in the following claims.