Systems and methods for determining changes in leg length in hip surgery

Abstract

Systems and methods receive pre-operative, volume data for a patient's pelvis and a femur. A three-dimensional (3D) model is generated of the patient's pelvis and femur. A hologram of the patient's native hip is generated from the 3D model. The patient's pelvis is registered relative to a pelvic coordinate system. The hologram is displayed and the patient is aligned with the hologram. The 3D coordinates of a selected point on the femur is determined relative to the pelvic coordinate system. Following implantation of prosthetic hip components, the hologram of the patient's native hip is displayed again and the patient is aligned with the hologram. The 3D coordinates of the selected point on the patient's femur are again determined. One or more changes to leg length, offset, or Anterior-Posterior (AP) position are determined based on the two 3D coordinates determined for the selected point. The one or more changes to leg length, offset, or Anterior-Posterior (AP) position are displayed

Description

[0001] SYSTEMS AND METHODS FOR DETERMINING CHANGES IN LEG LENGTH IN HIP SURGERY TECHNICAL FIELD

[0002] This application relates generally to systems, methods, and apparatuses for determining changes in leg length, offset, and / or Anterior Posterior (AP) position occurring during hip surgery.

[0003] BACKGROUND

[0004] Human hip joints can suffer deterioration, for example, due to aging, deformity, illness, or injury. In total hip replacement or total hip arthroplasty (THA), orthopedic prosthetic implants are used to replace some or all of a hip joint in order to restore its use. Fig. 1 is an exploded view of an example hip implant 100. The hip implant 100 may include a femoral assembly 102 and an acetabular assembly 104. The femoral assembly 102 may include a femoral hip stem 106, a neck portion 112, and a femoral head 1 14. The acetabular assembly 104 may include an acetabular cup 120 and a liner 122 that fits within the acetabular cup 120. During the surgery, a portion of the patient’s native femur including the femoral head and a portion of the femoral neck is resected and replaced with the femoral assembly. A portion of the femoral hip stem is positioned within a femoral canal of the patient’s femur. The cup component and liner are implanted in the patient’ s acetabulum and the femoral head is received within the cup component.

[0005] Exemplary hip implants include the G7 OsseoTi acetabular components and the Avenir Complete femoral components from Zimmer Biomet Holdings, Inc. of Warsaw, IN, the Synergy hip system from Smith & Nephew, Inc. of Memphis, Tennessee, the Summit hip system available from Depuy Orthopaedic, Inc. of Warsaw, Indiana, and the Epoc Hip System available from Biomet, Inc. of Warsaw, Indiana, among others. The present invention also may be used with non-modular hip implants.

[0006] When a hip joint is replaced, changes in leg length, offset, and / or anterior- posterior (AP) position may occur. Leg length refers to the longitudinal extent of the leg, and may be measured, e.g., from a location on the pelvis down to some location along the leg, such as a point on the femur. Offset refers to the lateral or transverse dimension through the hip. The AP position refers to changes along an axis orthogonal to the longitudinal and lateral or transverse axes. Substantial changes, such as changes of 10 mm or more, in leg length, offset, and / or AP position as a result of hip replacement surgery can be undesirable. For example, if a patient’s legs are of equal length before surgery, and the leg of the hip being operated on is lengthened, e.g., 10 mm or more, such an outcome may be undesirable as it can result in an unstable hip joint, potentially leading to repeated hip dislocations and the need for revision, i.e., corrective surgery. Unequal leg lengths can also lead to trunk imbalance, excessively tight tissues, and discomfort. Nonetheless, in some cases, it may be a goal for there to be a certain change in leg length, offset, and / or AP position following surgery.

[0007] Accordingly, the position and orientation of the prosthetic hip components can be of critical importance in achieving successful THA. The cup component, which has a partially spherical form, may have a center and the position of the cup component may be defined based on the x,y,z coordinates of the cup center. The orientation of the cup component may be defined relative to a cup axis, e.g., a line passing through the cup center and perpendicular to the plane of the cup’s opening face. Acetabular cup position is traditionally described in terms of the position of the center of rotation, anteversion, and inclination (also referred to as abduction). Improper acetabular cup placement is associated with higher dislocation rates, range of motion (ROM) limitations due to impingement, uneven component wear and, ultimately, higher rates of revision.

[0008] Prior to surgery, a surgeon may choose particular hip components, and may plan their position within the hip in order to accomplish a particular goal for the surgery, such as optimizing the changes in leg length, offset, and / or AP position for the patient. In some cases, optimizing the changes may mean minimizing changes to leg length, offset, and / or AP position resulting from the surgery. In other cases, it may mean achieving particular changes to leg length, offset, and / or AP position. The particular components and their locations and orientations may be selected based on patient-specific data, such as patient anatomy.

[0009] THA is typically performed using either posterior, superior, lateral, anterolateral or anterior approaches to the hip joint. For the anterior approach, the patient is placed in a supine position. SUMMARY

[0010] Briefly, the present disclosure relates to systems and methods for determining changes in leg length, offset, and / or Anterior Posterior (AP) position occurring during hip surgery, e.g., Total Hip Arthroplasty (THA). The systems and methods may include generating one or more patient- specific surgical plans, such as a plan for performing total hip arthroplasty (THA) on a patient. The systems and methods may generate a three-dimensional (3D) model of a portion of the patient’s anatomy, such as the patient’s pelvis, e.g., from volume data, such as Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) as examples. The systems and methods may include a library of 3D models of prosthetic hip components, such as femoral hip stems, femoral heads, acetabular cup components, liners, etc. The systems and methods may include a planning tool, which may be utilized to select particular hip component models from the library and to place them on or in the 3D pelvis and / or femur model. The component models may be placed on and / or integrated into the 3D models of the pelvis and femur at planned positions and / or in planned orientations, e.g., to achieve one or more goals of the surgery, such as planned inclination and / or anteversion of the cup component and / or restoration or changes to the patient’ s leg length, offset, and / or anterior-posterior (AP) position.

[0011] The surgical plan may specify the selected prosthetic components to be implanted in the patient’s body as well as the components’ positions and / or orientations. For example, the surgical plan may specify a particular cup component and its position at a patient’s acetabulum, e.g., depth, and an orientation within the acetabulum. The plan may also specify a planned position and / or orientation of prosthetic stem component at the patient’s femur. Based on the selected stem and its planned position at the patient’s femur, one or more cuts to the neck of the femur may be planned to remove the native head of the femur but preserve the greater trochanter.

[0012] The systems and methods may generate virtual images, such as holograms (or files from which holograms may be rendered) from the surgical plan. For example, holograms may be generated of the selected components at their planned locations. In addition, holograms of surgical tools in planned positions for preparing the patient’s anatomy may also be generated. Holograms of the patient’s hip with the selected components at their planned locations may also be generated. During the surgery, the surgeon may wear a Virtual Reality (VR) and / or Mixed Reality (MR) Head-Mounted Device (HMD). The holograms generated during the planning phase may be transmitted to the VR / MR HMD. With the patient on the operating table, the patient’s pelvis may be registered in space. In some embodiments, a tracker may be attached to the patient’s pelvis and the registration of the patient’s pelvis may be set and / or transferred to this tracker. An exemplary registration is relative to an Anterior Pelvic Plane (APP) coordinate system having an origin. Optionally, the patient’s femur may also be registered. The registration may be performed by the VR / MR HMD, which may then display one or more of the holograms based on the registered pelvis and / or femur. For example, a hologram of the patient’s native hip - pelvis and operative femur may be presented. The surgeon may move the patient so that the patient’s pelvis and leg are aligned with the hologram of the pelvis and femur. A point may be selected on the patient’ s femur. The point may be a landmark located on the femur, such as the greater trochanter, the lesser trochanter, etc. Nonetheless, the selected point need not be a landmark. The tip of a digitizer may be placed at the selected point. With the tip of the digitizer placed at the selected point, the VR / MR HMD may detect the digitizer and compute leg length, offset, and / or AP position relative to the APP coordinate system based on the selected point.

[0013] The surgeon may then proceed with the surgery. For example, the surgeon may prepare the acetabular cup bed and implant the acetabular cup component. The surgeon may also resect the native femoral head and implant the femoral components. For example, The surgeon may move physical surgical tools to coincide with the holograms displayed by the VR / MR HMD and may implant physical components to coincide with the holograms. In addition, the surgeon may cut the patient’s femur based on the holograms illustrating the neck cuts. With the prosthetic components implanted, the surgeon may reduce the patient’s hip.

[0014] Following the reduction of the patient’s hip, the VR / MR HMD may again display the hologram of the patient’s native hip - pelvis and operative femur. The surgeon may again move the patient so that the patient’s pelvis and leg are aligned with the hologram of the pelvis and femur. The tip of the digitizer may again be placed at the selected point on the patient’ s femur. With the tip of the digitizer placed at the selected point, following implantation of the prosthetic components and a reduction of the hip, the VR / MR HMD may detect the digitizer and compute post- reduction leg length, offset, and / or AP positions relative to the APP coordinate system based on the selected point. The VR / MR HMD may also compare the pre-surgery leg length, offset, and / or AP positions to the post-reduction leg length, offset, and / or AP positions and present changes to the leg length, offset, and / or AP positions as a result of the surgery.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The description below refers to the accompanying drawings, of which:

[0017] Fig. 1 is an exploded view of an example hip implant;

[0018] Fig. 2 is a schematic illustration of an example data capture system in accordance with one or more embodiments;

[0019] Fig. 3 is a schematic illustration of an example of the surgical planning system in accordance with one or more embodiments;

[0020] Fig. 4 is an illustration of an example planning window in accordance with one or more embodiments;

[0021] Fig. 5 is an illustration of another example planning window in accordance with one or more embodiments;

[0022] Fig. 6 is an illustration of another example planning window in accordance with one or more embodiments;

[0023] Fig. 7 is an illustration of another example planning window in accordance with one or more embodiments;

[0024] Fig. 8 is an illustration of another example planning window in accordance with one or more embodiments;

[0025] Fig. 9 is an illustration of another example planning window in accordance with one or more embodiments;

[0026] Fig. 10 is a schematic illustration of an example of an operating room environment in accordance with one or more embodiments;

[0027] Fig. 11 is an illustration showing an example of a randomly placed tracker attached to a pelvis. In some embodiments the tracker may be affixed to the pelvis using pins in accordance with one or more embodiments;

[0028] Fig. 11 A is a schematic illustration of an example of a digitizer in accordance with one or more embodiments; Fig. 12 is an illustration showing an example of an instruction screen appearance when a first point is being entered using a mixed reality head-mounted device as a first step in registration of a planned surgery relative to the patient in surgery in accordance with one or more embodiments;

[0029] Fig. 13 is an illustration of an example of the ipsilateral anterior superior iliac spine point being entered in accordance with one or more embodiments;

[0030] Fig. 14 is an illustration showing an example of the distance information provided to the surgeon as the third point is entered in an accordance with one or more embodiments;

[0031] Fig. 15 is an illustration showing an example of a result of the completed linked-pair point patient-specific registration process in accordance with one or more embodiments;

[0032] Fig. 16 is a schematic illustration of an example of a User Interface (UI) in accordance with one or more embodiments;

[0033] Fig. 17 is a schematic illustration of an example of a UI in accordance with one or more embodiments;

[0034] Fig. 18 is a schematic illustration of an example of a UI in accordance with one or more embodiments;

[0035] Fig. 19 is a schematic illustration of an example of a view through a Virtual Reality and / or Mixed Reality device in accordance with one or more embodiments;

[0036] Fig. 20 is a schematic illustration of an example of a UI in accordance with one or more embodiments;

[0037] Fig. 21 is a schematic illustration of an example of a UI in accordance with one or more embodiments;

[0038] Fig. 22 is a schematic illustration of an example of a UI in accordance with one or more embodiments;

[0039] Fig. 23 is a schematic illustration of an example of a hologram in accordance with one or more embodiments;

[0040] Fig. 24 is a schematic illustration of an example of a view through a Virtual Reality and / or Mixed Reality device;

[0041] Fig. 25 is a schematic illustration of an example of a UI in accordance with one or more embodiments; and

[0042] Fig. 26 is a schematic illustration of an example of a UI in accordance with one or more embodiments. DETAILED DESCRIPTION OF ILLUSTRATIVE

[0043] EMBODIMENTS

[0044] Pre-operative Planning Phase

[0045] Fig. 2 is a schematic illustration of an example data capture system 200 in accordance with one or more embodiments. The system 200 may include an imaging apparatus 202, such as Computed Tomography (CT) scanner, for generating patientspecific, pre-operative volume data 204. The CT scanner 202 may generate a three- dimensional (3D) data set, e.g., an array, of volume elements, i.e., voxels, each having a radiographic density value. The volume data may be in the form of files or objects. The data capture system 200 may further include or be in communication with a surgical planning system 300. Specifically, data, such as the volume data 204, may obtained for a patient who is to undergo a surgical procedure. The volume data 204 may be obtained of that portion of the patient’ s anatomy on which the surgery is to be performed. For example, a patient may be diagnosed with hip joint failure, and may require total hip arthroplasty (THA) surgery. In this case, one or more low cost, low dose CT scans of the patient’s hip may be taken.

[0046] It should be understood that patient-specific volume data may be obtained in other ways besides or in addition to CT scans. For example, one or more of Magnetic Resonance Imaging (MRI), conventional radiographs (X-rays), bi-planar or multiplanar simultaneous radiographs, or ultrasonic images, may be taken of the patient. The one or more digital images (CT, magnetic, radiographic, ultrasonic, etc.) may provide three-dimensional (3D) volume data regarding the surface and / or structure of the portion of the patient’s anatomy that was scanned, e.g., the patient’s hip.

[0047] 3D volume data may be generated in other ways. For example, 3D volume data for a patient’s hip may be predicted or derived from a single image, a statistical model, one or more measurements taken of the patient’s hip, etc.

[0048] The obtained volume data may be transferred to the surgical planning system 300, as indicated by arrow 208. Fig. 3 is a schematic illustration of an example of the surgical planning system 300 in accordance with one or more embodiments. The surgical planning system 300 may include a user interface (UI) engine 302, a modeling tool 304, a planning tool 306, and a data store 308. The surgical planning system 300 may include or have access to a display 312. The surgical planning system 300 may receive the patientspecific volume data 204. The surgical planning system 300 may create one or more surgical plans, such as plan 314, for the surgical procedure, e.g., THA. In some embodiments, the system 300 may also include a hologram generator 318 and may generate one or more holograms 320 or files from which the one or more holograms 320 may be generated.

[0049] Suitable tools for generating 2D and / or 3D models of anatomical structures from volume or shape data include the OsiriX image processing software from Pixmeo S ARL of Bernex Switzerland, the TraumaCad pre-operative planning system, and the MAKOplasty Total Hip Application prc-opcrativc and intra-operative planning system. Nonetheless, those skilled in the art will understand that other image processing software may be used.

[0050] One or more of the patient data 204, the surgical plan 314, and the holograms 320 may be implemented through one or more data structures, such as files, objects, etc., stored in the electronic memory of a data processing device.

[0051] One or more components of the surgical planning system 300 may be or may include software modules or libraries containing program instructions pertaining to the methods described herein, that may be stored on non-transitory computer readable media, and executed by one or more processors of a data processing device. In some embodiments, one or more components of the surgical planning system 300 may each comprise registers and combinational logic configured and arranged to produce sequential logic circuits. In other embodiments, various combinations of software and hardware, including firmware, may be utilized to implement the present disclosure.

[0052] As noted, the surgical planner may select one or more prosthetic components, e.g., implants, to be used in a surgical procedure, such as a cup component and / or a femoral stem component and plan their placement in the patient’s body. The plan for the cup component in addition to the make, model, and size of cup component may include a planned position, including a depth and / or an orientation within the acetabulum. The plan may also include the shape of the cup bed at the patient’s acetabulum to receive the cup component. For the femoral stem component, the plan may identify the make, model, and size of femoral stem and may specify the position of the femoral stem component within the femur and / or its orientation relative to the femoral coordinate system and / or tibial coordinate system.

[0053] In some embodiments, the plan may incorporate 3D models of one or more tools, such as a registration and tracking device, an acetabular reamer, and a cup impactor, among others.

[0054] Fig. 4 is an illustration of an example planning window 400 generated by the surgical planning system 300 and presented on the display 314 in accordance with one or more embodiments. The planning window 400, which may be created by the UI engine 302, includes a model pane 402 presenting a 3D model of at least a portion of the patient’s hip 404 and a planning pane 406. The hip model 404 may be a 3D surface model generated by the modeling tool 304 from the volume data 204, e.g., the CT scan data. In other embodiments, the hip model 404 may be a solid model. User controls 408a-c, such as rotate, translate, and zoom in / out, respectively, may be provided for controlling how the hip model 404 appears in the model pane 402. The hip model 404 may include the pelvis 410 and the operative femur 412, e.g., the right femur. In other embodiments, modeling tool 304 may generate and operate on 3D solid models and / or a combination of surface and solid models.

[0055] The hip model 404 may present the patient’ s hip as captured during the CT scan, e.g., with the right native hip joint. The modeling tool 304 may be configured to create sub-volumes from the original volume data 204. More specifically, the modeling tool 304 may create a pelvis sub-model that includes the patient’s pelvis and a femur sub-model that only includes the operative side femur, e.g., the right femur. In some embodiments, the modeling tool 300 may create a sub- volume by changing the radiographic density of the voxels that are not part of the sub-volume to a value for soft tissue such that the voxels will not appear on a synthetic DR. In other embodiments, the modeling tool 304 may create the sub-models by removing the voxels from the original volume data 204 that correspond to structures or elements not included in the particular sub-model. The modeling tool 304 can thus generate separate models of both the operative femur and the pelvis.

[0056] The modeling tool 304 and / or the predictive synthetic DR generator 308 can the use the models as masks, e.g., to edit the voxels within the femoral model for example. This can also all be automated with machine learning, just having a machine study what we do so that it can be replicated. For example, to model the pelvis and the cup component, the modeling tool 304 may use the 3D surface model of the femur as a mask. The predictive synthetic DR generator 308 may take all of the voxels that exist inside of the femur model and change their values, e.g., to new radiographic density values, such as soft tissue, air, etc. In addition, since the modeling tool 304 knows where the cup component will be (position and / or orientation), the modeling tool 304 may identify the volume of bone that is overlapping the volume of the cup component and remove that volume of bone so it is not shown in the planning images because it would have been removed by the surgery. That is, the modeling tool 304 can determine where two objects (the acetabular bone and the cup) are overlapping and determine which object to keep and which to remove.

[0057] The modeling tool 304 also may create 3D models for the different submodels, e.g., pelvis, femur, etc. The planning pane 406 may include an area 414 through which the planner may select, e.g., using checkbox elements, which submodels to display on the model pane 402. fhe planning pane 406 also may include sub-panes containing user interface elements for planning the surgery. For example, the planning pane 406 may include a ‘Cup Plan’ sub-pane 416 for planning the cup component and a ‘Stem Plan’ sub-pane 418 for planning the femoral stem.

[0058] Fig. 5 is an illustration of another example planning window 500 in accordance with one or more embodiments. Here, the operative, e.g., right, femur is removed and models 502 and 504 of the selected cup component and liner are displayed at the patient’ s acetabulum. In addition, an image 506 representing the Anterior Pelvic (AP) Plane is shown. In some embodiments, the planner may plan the location, e.g., position and orientation, of the cup component 502 in the acetabulum relative to the AP Plane 506. For example, the planning pane 406 may include elements 508 and 510 for setting the operative anteversion (OA) and operative inclination (OI) of the cup component. The elements 508 and 510 may include sliders, numeric data entry boxes, and plus / minus controls.

[0059] In some embodiments, the patient’s pelvis and / or femur may be registered and tracked during the surgical procedure. For example, a physical device may be docked to the patient's pelvis to register the pelvis. The device may also be tracked to maintain registration of the pelvis during the procedure. In some embodiments, the planning phase may include planning the device used to register and track the patient’s pelvis.

[0060] Fig. 6 is an illustration of another example planning window 600 in accordance with one or more embodiments. Here, a 3D model 602 of a registration and tracking device may be docked to the model of the pelvis 402. The model of the device 602 may include a tracker 604 that can be detected by a VR / MR HMD. A code on the tracker may expose a spatial 3D coordinate system. The planning tool 306 may construct one or more translation matrices that translate positions and / or orientations from the AP Plane coordinate system to the spatial coordinate systems of the tracker 604. The surgical planner may determine one or more adjustments to the registration and tracking device in order for the physical device to dock to the patient’s pelvis as planned.

[0061] The surgical planner may plan the position, shape, and orientation of the cup bed to receive the cup component, c.g., to achieve the one or more goals of the surgery. The cup bed refers to the ideal surgically created bone surface to receive the cup component in the planned position and / or orientation.

[0062] In some embodiments, computer-generated, three-dimensional (3D) models, such as Computer Aided Design (CAD) models, of one or more surgical tools may be stored in the data store 310. 3D surface models of the surgical tools may be generated from these models and also stored in the data store 310. In some embodiments, only the 3D surface models may be included in the data store 310. In some embodiments, 3D surface models of one or more standard surgical tools, such as a standard acetabular reamer with a standard cutting basket and a standard acetabular cup impactor may be included in the data store 310. Holograms that include a reamer and / or cup impactor may be based on these surface models of a standard reamer and / or cup impactor.

[0063] However, in other embodiments, 3D models for actual, physical reamers and / or cup impactors including entire product families from one or more manufacturers, e.g., Stryker Corp, of Kalamazoo, MI, Greatbatch, Inc. (now Integer Holdings Corp.) of Plano, TX, Ortho Solutions UK Ltd. of Essex, UK, Zimmer Biomet Holdings, Inc. of Warsaw, IN, Depuy Synthes of Raynham, MA, etc., may be included in the data store 310. Furthermore, 3D models for different sizes of cutting baskets and different sizes of acetabular cups may be included in the data store 310. During the surgical planning phase, 3D models corresponding to the particular reamer and the particular cup impactor planned for use by the surgeon may be selected from the data store 310 and used in creating the surgical plan 314.

[0064] In some embodiments, the surgical planner may determine the location of an acetabular reamer at the 3D model of the pelvis, e.g., relative to the AP Plane coordinate system, to prepare the cup bed as planned. For example, the acetabular reamer may have a handle defining a longitudinal axis. The surgical planner may position a 3D model of the acetabular reamer so that the cutting basket of the reamer is positioned in the acetabulum to prepare the cup bed as planned.

[0065] Fig. 7 is an illustration of another example planning window 700 in accordance with one or more embodiments. In addition to the pelvis model 410, the model pane 402 also includes a model of a reamer tool 702. The planner may position and / or orient the reamer tool 702 at the final position and / or orientation for preparing the patient’s acetabulum to receive the cup component.

[0066] The surgical planner also may determine the location of a cup impactor at the 3D model of the pelvis, e.g., relative to the AP Plane coordinate system, to implant the cup component in the cup bed as planned. For example, the cup impactor may have a handle defining a longitudinal axis. The surgical planner may position a 3D model of the cup impactor so that the longitudinal axis defined by the handle positions the cup component at the end of the cup impactor in the cup bed as planned.

[0067] Fig. 8 is an illustration of another example planning window 800 in accordance with one or more embodiments. In addition to the pelvis model 410, the model pane 402 also includes a model of a cup impactor tool 802. The planner may position and / or orient the cup impactor tool 802 at the final position and / or orientation for implanting the cup component in the patient’s acetabulum at the planned position and / or orientation.

[0068] As noted, in addition to planning the cup component, the planner may also plan the femoral stem component.

[0069] Fig. 9 is an illustration of another example planning window 900 in accordance with one or more embodiments. In addition to the pelvis model 410, the cup component 402, and the liner 404, the model pane 402 also includes a model of the stem component 902 as planned.

[0070] In some embodiments, the hologram generator 318 may generate the following holograms, which may be included in the surgical plan 314: the intact, native femur and pelvis; the modified pelvis with the planned acetabular components; the modified femur with the planned femoral component(s), e.g., femoral stem and head; and the modified pelvis and the modified femur as reduced.

[0071] Surgical Phase

[0072] The surgical plan 314 and the holograms 320 may be transmitted to the surgeon performing the surgical procedure who may review them.

[0073] Fig. 10 is a schematic illustration of an operating room environment 1000 in accordance with one or more embodiments. Disposed in the operating room 1000 is an operating table 1002 on which a patient 1004 (partially shown) is positioned for a surgical procedure. One or more surgeons and / or assistants may be in the operating room 1000, such as surgeons 1006 and 1008. One or more of the surgeons 1006 and 1008 may be wearing a Virtual Reality (VR) and / or Mixed Reality (MR) device, such as VR / MR headsets or head mounted devices (HMDs) 1010 and 1012 worn by the surgeons 1006 and 1008, respectively. fhe patient 1004 may be undergoing a Total Hip Arthroplasty (THA) procedure on his right hip 1014. The patient 1004 may be lying on the operating table 1002 in a supine position. For example, the patient 1004 may be lying on his back. Also shown in phantom are the patient’s pelvis 1016 and his right femur 1018. In other embodiments, the patient may be lying in a lateral position. To perform the THA procedure the surgeons 1006 and 1008 may use one or more surgical instraments and may implant one or more prosthetic components in the patient 1004. For example, the surgeon 1006 is using a cup impactor instrument 1020, which may be used to implant a prosthetic cup component in the patient’s acetabulum. The surgeon 1008 is using a retractor 1022 to provide access to the patient’s right hip 1014, e.g., through an incision.

[0074] Fig. 10 is a highly schematized illustration meant for explanation purposes only. For example, it should be understood that the patient and / or the surgeon(s) may be in other places during actual THA surgery.

[0075] The specific prosthetic components and the locations and orientations, e.g., positions, at which they are to be implanted in the patient 1004 may be specified in the surgical plan 124. The VR / MR HMDs 1010 and 1012 may present information to the surgeons 1006 and 1008 during the surgical procedure. For example, the VR / MR HMDs 1010 and 1012 may present holograms of one or more implants and / or surgical instruments at least portions of which may otherwise be hidden from the surgeons 1060 and 1008, e.g., portions of physical implants or tools represented by the holograms may be located below the patient’s skin. The VR / MR HMDs 1010 and 1012 may also present information that assists the surgeons 1006 and 1008 in implanting the prosthetic components at the desired, e.g., planned, positions and / or orientations. For example, the VR / MR HMDs 1010 and 1012 may present holograms of the positions of surgical instruments for preparing the patient’s anatomy to receive the prosthetic components. The surgeons 1006 and 1008 may move, e.g., position, the physical instruments so that they are aligned with the holograms. The VR / MR HMDs 1010 and 1012 may also present holograms of the prosthetic components at the desired, e.g., planned locations. The surgeons 1006 and 1008 may implant the prosthetic components so that they are aligned with the holograms of the components. That is, the VR / MR HMDs 1010 and 1012 may be configured to operate as surgical navigation systems.

[0076] Suitable VR / MR HMDs include the HoloLens series of mixed reality devices from Microsoft Corp, of Redmond, WA, the Vision Pro device from Apple, Inc., the Magic Leap Two device from Magic Leap, Inc. of Plantation, FL, and the Blade smart glasses from Vuzix Corp, of West Henrietta, NY, among others.

[0077] In some embodiments, the patient’s pelvis 1016 may be registered during the THA procedure. In some embodiments, the patient’s pelvis 1016 may also be tracked.

[0078] A navigation application running on the VR / MR HMDs 1010 and 1012 may be opened and the surgical plan 124 and the exported files 126 (e.g., holographic content to be projected) may be opened. A tracker 1030 may be affixed to the patient’s pelvis. The tracker 1030 may be randomly attached to the patient’s pelvis. Registration of the patient’s pelvis may be achieved using a linked-paired-point matching method. This is similar to a basic paired-point matching method except the system knows the exact distances between the points and so the workflow may proceed as follows.

[0079] In some embodiments, the tracker 1030 used to register the patient’s pelvis may be configured such that it may be detected and recognized by the VR / MR HMDs 1010 and 1012. For example, the tracker 1030 may include a planar target plate, which may have a front face or surface and a back face or surface. A two-dimensional (2D) code may be disposed on the front face. The 2D code may be formed from an arrangement of black and white blocks. For example, the 2D code may be formed from a plurality of black and white pixels. A 2D code may also be presented on the back face of the target plate. The codes on the front and back faces may be different from each other. That is, the arrangement of pixels may be different. In some embodiments, the target plate may be square. However, it should be understood that the target plate may take other two-dimensional shapes, such as rectangular, oval, round, etc.

[0080] A spatial coordinate system may be associated with the 2D codes of the target plate, and the VR / MR HMDs 1010 and 1012 may be configured to detect the 2D code in the operating room environment and access the spatial coordinate system associated with the detected 2D code. The coordinate system may include an origin and three orthogonal axes, such as an x-axis, a y-axis, and a z-axis. The x-axis may point to the right, the y-axis may point up, and the z-axis may point out of the target plate. In some embodiments, the origin may be in the middle of the target plate on a line connecting the centers of the 2D codes on the front and back surfaces.

[0081] In some embodiments, the blocks or pixels of the 2D codes may be aligned in rows and columns that are orthogonal to each other. The x-axis and the y-axis may be aligned with these rows and columns. Furthermore, the 2D codes may be planar and the z-axis may extend at a right angle to the plane of the 2D code. The spatial coordinate system may thus be aligned with the 2D code. That is, the spatial coordinate system can be derived by the VR / MR HMDs 1010 and 1012 upon detecting the 2D code in space.

[0082] In some embodiments, one or more computer program applications (apps) may be created and loaded onto the VR / MR HMDs 1010 and 1012. The apps may include a planning application for running a surgical plan created for a patient and a navigation application for detecting a 2D code, deriving the coordinate system associated with the detected 2D code, and utilizing a transformation matrix to present and anchor one or more holograms at planned positions. The navigation app running on the VR / MR HMDs 1010 and 1012 may be configured to associate the 2D codes on the front and back faces with the coordinate system. Fig. 11 shows a randomly placed tracker attached to a pelvis. In some embodiments the tracker may be affixed to the pelvis using pins in accordance with one or more embodiments. Fig. 11 also shows a digitizer. Next, once the VR / MR HMD identifies the tracker attached to the pelvis, the VR / MR HMD may search for the digitizer. Fig. 11 A is a schematic illustration of another digitizer in accordance with one or more embodiments.

[0083] The VR / MR HMD may direct the surgeon to enter a first point (e.g., Point 1) on the pelvis relative to the randomly attached tracker using the digitizer. The first point (Point 1) may be the ipsilateral anterior superior iliac spine point. The first point may be a landmark that can be identified by the surgeon. The surgeon may place the tip of the digitizer in the location of the first point and use a verbal command, such as “store point”, to enter the first point. In other embodiments, a gesture option may be used to enter the first point. Fig. 12 shows an instruction screen appearing when the first point is being entered in accordance with one or more embodiments. The first point may be the pubic symphysis. However, in other embodiments different first points may be used.

[0084] The VR / MR HMD may then direct the surgeon to enter a second point (Point 2) on the pelvis using the digitizer. The second point may be the contralateral anterior superior iliac spine The VR / MR HMD “knows” the distance between Point 1 and Point 2. Therefore, as the surgeon moves the digitizer toward the contralateral anterior superior iliac spine, the VR / MR HMD may displays how close the digitizer is to the anticipated location of the second point. The objective being to reach the “0 mm” distance between the known distance from the surgical plan and the distance as calculated by the VR / MR HMD between the stored first point and the current location of the digitizer in the surgical field. When the digitizer reaches the second point, e.g., the VR / MR HMD displays “0 mm”, the surgeon may store the second point. In this way, the second landmark’s position is refined beyond an “unlinked paired-point”. This restricts possible error to be along a radius from the first point.

[0085] Since the VR / MR HMD knows both the first and second points from the surgical plan, the VR / MR HMD device can track and display how close the tip of the digitizer is to being the known distance from the first point. This is significant because if the ipsilateral ASIS is digitized by the surgeon independently, e.g., not tethered to the first point, then there is a larger potential error. By displaying the known distance and moving the digitizer to get it to zero, the VR / MR HMD assists in finding the second point. This technique reduces the potential error in that any new error can only be on a tangent to the radius from the first point to the second point. This method improves the accuracy of the registration process.

[0086] Fig. 13 is an illustration of the ipsilateral anterior superior iliac spine point being entered in accordance with one or more embodiments. Note that the difference between the known distance between the first and second point, and the actual distance between the entered basepoint and the entered ipsilateral ASIS point is zero. This information improves the accuracy of the registration of the patient’s pelvis in surgery.

[0087] Once the second point is entered, the VR / MR HMD may automatically switch to assisting the surgeon locate and digitize the third point. Since the VR / MR HMD has the planned locations for the three points, it knows the linear distance from the first and third points as well as from the second and third points, e.g., the distance between Point 1 and Point 3 and Point 2 and Point 3. The VR / MR HMD may display the differences between both of those distances and the tip of the digitizer. So as the surgeon moves the digitizer to the third point, the VR / MR HMD can display the distances from the first and second points, again with the objective to reach “Omm” for both distances. When the surgeon moves the digitizer such that displayed distance relative to both the first and second points is as close to zero as possible, the surgeon may again give the command “store point” and the linked-pair point registration process is completed. Instead of just freely entering the third point, having the distance information tethers the third point to the first two. So the accuracy of this third point is greater than it would be with free hand digitization because the point is at the intersection of being on the surface of the bone and also specific distances from the other two.

[0088] Fig. 14 shows the distance information provided to the surgeon as the third point is entered in an accordance with one or more embodiments.

[0089] Once the third point is entered, the VR / MR HMD now knows where the randomly placed tracker is in space relative to the pelvis and all of the holographic content can be displayed relative to the patient’s AP Plane. That is, with the patient’s pelvis is registered, the VR / MR HMD knows the position and orientation of the patient's pelvis in space and the position and orientation of the planned cup in space. A hologram of an acetabular reamer with its center coincident with the planned cup center can be displayed and a hologram of the cup and cup impactor in the planned position and orientation can also be displayed to allow the surgeon to prepare and place the cup correctly as planned relative to that patient.

[0090] When digitizing the points on the patient’s pelvis, the digitizer may include a sharp tip, which may be used to pierce the patient’s skin and directly contact the respective point or landmark, e.g., the two ASIS points and the pubic symphysis. In other embodiments, instead of piercing the patient’s skin, the tip of the digitizer may be pushed down on the skin above the respective points or landmarks. The tip of the digitizer may compress the skin and approach but not directly contact the points or landmarks. This technique will likely provide an accurate angular registration of the patient’s pelvis. For example, it will accurately determine the orientation of the APPlane of the patient’s pelvis. However, because the digitizer is not being brought into direct contact with the landmarks, e.g., the two ASIS points and the pubic symphysis, this technique may be less accurate in determining the position of the APPlane.

[0091] With the patient on the operating table in the supine position, the surgeon may direct the VR / MR HMD to display the femur hologram. Fig. 15 is a schematic illustration of a femur hologram as displayed by the VR / MR HMD overlaid on a model of a pelvis and a femur. The surgeon may move the patient so that the patient’ s pelvis and femur are aligned with the femur hologram. For example, the surgeon may move the patient’s leg so that the patient’s femur is aligned with the femur portion of the femur hologram.

[0092] The surgeon may next enter a ‘Measure Length’ command in the VR / MR HMD. Fig. 16 is a schematic illustration of an example of a User Interface (UI) 1600 as displayed by the VR / MR HMD. The UI 1600 may include a ‘Measure Length’ command 1602, which may be selected by the surgeon as shown.

[0093] In some embodiments, the VR / MR HMD may accept measurements by digitizers having different lengths. The surgeon may enter a command choosing the length of the digitizer being used by the surgeon. Fig. 17 is a schematic illustration of a UI 1700 as displayed by the VR / MR HMD. The UI 1700 may include a ‘Short’ command option 1702 and a ‘Long’ command option 1704. The surgeon may select the ‘Short’ command option 1702, as shown.

[0094] The surgeon may next select a ‘Turn On Digitizer’ command as presented by the VR / MR HMD. Fig. 18 is a schematic illustration of an example of a UI 1800 with a ‘Turn On Digitizer’ command button 1802. The surgeon may then place the tip of the digitizer at the selected point on the patient’s femur. Fig. 19 is a schematic illustration of the view through the VR / MR HMD as the surgeon places the tip of the digitizer at the selected point on the patient’s femur.

[0095] In some embodiments, the selected point may be a landmark on the femur that may be readily identified by the surgeon, such as the greater trochanter or the lesser trochanter. In other embodiments, the selected point is not a landmark. For example, the surgeon may mark the selected point on the femur, such as with a drill bit, a pin, etc. so that the surgeon may return to the selected point following the acetabular and femoral components being implanted.

[0096] The VR / MR HMD may capture the 3D coordinates of the location of the tip of the digitizer when placed at the selected point. The VR / MR HMD may determine the 3D coordinates relative to the APP coordinate system as previously determined for the patient’s pelvis, when the patient’s pelvis was registered in the operating room. Next, the VR / MR HMD may compute the leg length, offset, and / or AP position relative to the origin of the APP coordinate system based on the selected point whose 3D coordinates were captured by the VR / MR HMD.

[0097] In some embodiments, the VR / MR HMD may determine a longitudinal vector from the origin of the APP coordinate system to the selected point. The VR / MR HMD also may determine a horizontal vector from the origin of the APP coordinate system to the selected point. The VR / MR HMD may utilize these vectors to determine the leg length, offset, and / or AP position of the femur based on the selected point.

[0098] The VR / MR HMD may display the computed leg length, offset, and / or AP position to the surgeon. Fig. 20 is a schematic illustration of an example of a UI 2000 as presented to the surgeon with the computed leg length, offset, and / or AP position.

[0099] The surgeon may proceed to implant the planned acetabular and femoral components and reduce the patient’s hip.

[0100] With the prosthetic components implanted and hip reduced, the surgeon may direct the VR / MR HMD to detect the digitizer. Fig. 21 is a schematic illustration of an example of a UI 2100 as presented by the VR / MR HMD with a ‘Turn On Digitizer’ command, which may be selected by the surgeon as shown. The surgeon may next direct the VR / MR HMD to perform a compare length operation. Fig. 22 is a schematic illustration of a UI 2200 as presented by the VR / MR HMD with a ‘Compare Length’ command, which may be selected by the surgeon as shown.

[0101] Again, to the extent different length digitizers are supported by the VR / MR HMD, the surgeon may enter a command choosing the length of the digitizer being used by the surgeon.

[0102] The surgeon may direct the VR / MR HMD to once again display the femur hologram. Fig. 23 is a schematic illustration of an example of a femur hologram as displayed by the VR / MR HMD overlaid on a model of a pelvis and a femur. While not shown by the model of Fig. 22, at this point the femur native head would be removed and replaced with the femoral components. Furthermore, the prosthetic femoral head would be placed in the prosthetic acetabular components. Again, the surgeon may move the patient so that the patient’s pelvis and femur arc aligned with the femur hologram. For example, the surgeon may move the patient’s leg so that the patient’s femur is aligned with the femur portion of the femur hologram.

[0103] The surgeon may then place the tip of the digitizer at the same selected point on the patient’ s femur that was used to measure leg length, offset, and / or AP position of the patient’s native hip. Fig. 24 is a schematic illustration of an example of the view through the VR / MR HMD as the surgeon places the tip of the digitizer at the same selected point on the patient’s femur.

[0104] The VR / MR HMD may capture the 3D coordinates of the location of the tip of the digitizer when placed at the same selected point. The VR / MR HMD may determine the 3D coordinates of the tip of the digitizer relative to the origin of the APP coordinate system. Next, the VR / MR HMD may compute new leg length, offset, and / or AP position values relative to the origin of the APP coordinate system based on the selected point whose 3D coordinates were captured by the VR / MR HMD.

[0105] The VR / MR HMD may compare the newly determined values with the values computed for the patient’s native hip and may calculate any changes in leg length, offset, and / or AP position. The VR / MR HMD may presented the determined changes in leg length, offset, and / or AP position to the surgeon. Fig. 25 is a schematic illustration of an example of a UI 2500 as presented and seen through the VR / MR HMD. The UI 2500 may present the newly determined values of leg length, offset, and / or AP position as determined and the changes relative to the values determined for the native hip. In some embodiments, the changes may be shown in parentheses. As illustrated in Fig. 25, no changes to either leg length or offset were determined as shown by the zero values in the parentheses.

[0106] Suppose, however, that the prosthetic acetabular and femoral components result in a change in leg length, offset, and / or AP position.

[0107] Fig. 26 is a schematic illustration of an example of a UI 2600 as presented and seen through the VR / MR HMD. The UI 2600 may present the newly determined values of leg length, offset, and / or AP position as determined and the changes relative to the values determined for the native hip. Here, the newly determined values differ from the original values as shown by the change values appearing in the parentheses. For example, the new leg length of 111 mm is a 4 mm change from the original value. The new offset of 112 mm is a 10 mm change from the original value.

[0108] As described, the present disclosure is free from having to place a tracker on the patient’s femur. The present disclosure is also free from having to register the femur or determine a femoral axis.

[0109] It should be understood that, in addition to being in the supine position, the patient may be in other positions for the surgical procedure. For example, in some embodiments, the patient may be in a lateral position, e.g., for the lateral approach. As described, the VR / MR HMD may display a hologram of the native hip with the hip in a lateral position and the surgeon may move the patient’s leg to be aligned with the hologram of the native hip. The surgeon may then digitize a point on femur, prior to the THA procedure, and the VR / MR HMD may calculate leg length, offset, and / or AP position of the femur. After the prosthetic components are implanted and the hip is reduced, the VR / MR HMD may again display the hologram of the native hip (or a hologram of the hip with the planned prosthetic components), and the surgeon may again digitize the same point on the femur. The VR / MR HMD may then compute the leg length, offset, and / or AP position. The VR / MR HMD may also compute changes in leg length, offset, and / or AP position. It should be understood that, in some embodiments, the order of the steps of the procedure may be changed, one or more steps may be added, and / or one or more steps may be removed. For example, in some embodiments, the surgeon may digitize the selected point on the femur before registering the pelvis. After digitizing the selected point, the VR / MR HMD may register the pelvis. With this embodiment, the step of displaying a hologram of the native pelvis and femur may be skipped. This embodiment may still provide sufficient accuracy in the determining leg length, offset, and / or AP position, including changes in leg length, offset, and / or AP position.

[0110] In some cases, a patient’s hip may be severely damaged, such that the hip may be in a clinically less useful position during the CT scan. For example, the femur may be externally rotated, such as 45 degrees, on the scanner. Such less useful scan positions may reduce the amount of offset measured by the VM / MR HMD compared to the amount of offset actually achieved during the THA procedure. In some embodiments, the modeling tool 304 and / or the planning tool 306 may be configured to rotate the model of the femur relative to the model of the pelvis in the planning application. The rotation may be around a user defined and / or calculated center of rotation. With the model of the femur rotated, the hologram generator 318 may proceed to generate one or more holograms, including a hologram of the native hip with the femur rotated. This hologram of the native hip with the femur rotated may be displayed and the surgeon may align the patient’s leg with the femur as displayed in the hologram when digitizing the selected point on the femur both before the surgical procedure and after the prosthetic components are implanted and the hip is reduced. By rotating the model of the femur, the accuracy of the offset determination or measurement may be improved.

[0111] The foregoing description of embodiments is intended to provide illustration and description, but is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from a practice of the disclosure. For example, while a series of acts has been described above, the order of the acts may be modified in other implementations. In addition, the acts, operations, and steps may be performed by additional or other modules or entities, which may be combined or separated to form other modules or entities. Further, non-dependent acts may be performed in parallel. Also, the term “user”, as used herein, is intended to be broadly interpreted to include, for example, a computer or data processing system, such as a computer running a chatbot or generative Artificial Intelligence (Al) system, or a human user of a computer or data processing system, unless otherwise stated.

[0112] Further, certain embodiments of the disclosure may be implemented as logic that performs one or more functions. This logic may be hardware-based, softwarebased, or a combination of hardware-based and software-based. Some or all of the logic may be stored in one or more tangible non-transitory computer-readable storage media and may include computer-executable instructions that may be executed by a computer or data processing system. The computer-executable instructions may include instructions that implement one or more embodiments of the disclosure. The tangible non-transitory computer-readable storage media may be volatile or nonvolatile and may include, for example, flash memories, dynamic memories, removable disks, and non-removable disks.

[0113] No element, act, or instruction used herein should be construed as critical or essential to the disclosure unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. Where only one item is intended, the term “one” or similar language is used. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

[0114] The foregoing description has been directed to specific embodiments of the present disclosure. It will be apparent, however, that other variations and modifications may be made to the described embodiments, with the attainment of some or all of their advantages. For example, the compiler 132 and the code generation system 200 may be combined into a single entity. Therefore, it is the object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of the disclosure.

[0115] What is claimed is:

Claims

CLAIMS1. A computer-implemented method comprising: receiving pre-operative, volume data for at least a portion of a patient’s pelvis and a femur; generating, by at least one processor, a three-dimensional (3D) model of the at least a portion of the patient’s pelvis and the femur from the volume data or from image data generated from the volume data; generating a hologram of the patient’s native hip from the 3D model of the at least the portion of the patient’ s pelvis and the femur; registering the patient’s pelvis in space, wherein the registering includes determining a pelvic coordinate system having an origin; displaying the hologram of the patient’s native hip a first time; aligning the patient with the hologram of the patient's native hip a first time; determining 3D coordinates of a selected point on the patient’s femur relative to the pelvic coordinate system; displaying the hologram of the patient’s native hip a second time; aligning the patient with the hologram of the patient’s native hip a second time; determining 3D coordinates of the selected point on the patient’s femur relative to the pelvic coordinate system; determining one or more changes to leg length, offset, or Anterior-Posterior (AP) position based on the two 3D coordinates determined for the selected point; and displaying the one or more changes to leg length, offset, or Anterior- Posterior (AP) position.

2. The computer-implemented method of claim 1 wherein the hologram is displayed by a Virtual Reality (VR) / Mixed Reality (MR) head mounted device (HMD).

3. The computer-implemented method of claim 2, wherein registering of the patient’s pelvis in space is performed by the VR / MR HMD.

4. The computer-implemented method of claim 1 , wherein the selected point on the patient’s femur comprises a landmark selected from a greater or lesser trochanter.

5. The computer-implemented method of claim 1, wherein determining 3D coordinates of the selected point on the patient’s femur relative to the pelvic coordinate system comprises: providing a digitizer in communication with the at least one processor; and placing a tip of the digitizer at the selected point to orient the selected point in the pelvic coordinate system.

6. The computer-implemented method of claim 1, wherein an event has occurred between the first time and the second time.

7. The computer-implemented method of claim 6, wherein the event comprises total hip arthroplasty (TH A).

8. The computer-implemented method of claim 1, further comprising, between the first time and the second time: implanting one or more acetabular components at a planned position or orientation at the patient’s pelvis; and implanting one or more femoral components at a planned position or orientation at the patient’s pelvis.

9. A system comprising: a memory, a display, and one or more processors in communication with the memory and the display, the one or more processors configured to: receive pre-operative, volume data for at least a portion of a patient’s pelvis and a femur; generate a three-dimensional (3D) model of the at least a portion of the patient’s pelvis and the femur from the volume data or from image data generated from the volume data; generate a hologram of the patient’s native hip from the 3D model of the at least the portion of the patient’s pelvis and the femur; register the patient’s pelvis in space, wherein the registering includes determining a pelvic coordinate system having an origin; display the hologram of the patient’s native hip on the display a first time;determine 3D coordinates of a selected point on the patient’ s femur relative to the pelvic coordinate system after alignment of the patient with the hologram of the patient’s native hip a first time; display the hologram of the patient’s native hip on the display a second time; determine 3D coordinates of the selected point on the patient’s femur relative to the pelvic coordinate system after alignment of the patient with the hologram of the patient’s native hip a second time; determine one or more changes to leg length, offset, or Anterior-Posterior(AP) position based on the two 3D coordinates determined for the selected point; and display the one or more changes to leg length, offset, or Anterior- Posterior(AP) position on the display.

10. The system of claim 9, wherein the display comprises a Virtual Reality (VR) / Mixcd Reality (MR) head mounted device (HMD).

11. The system of claim 10, wherein the one or more processors are part of the VR / MR HMD.

12. The system of claim 9, wherein the selected point on the patient’ s femur comprises a landmark selected from a greater or lesser trochanter.

13. The system of claim 9, further comprising a digitizer in communication with the at least one processor, the system operable to determine tje 3D coordinates of the selected point on the patient’s femur relative to the pelvic coordinate system by orienting a tip of the digitizer placed at the selected point.

14. The system of claim 9, wherein an event has occurred between the first time and the second time.

15. The system of claim 14, wherein the event comprises total hip arthroplasty (THA).

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