Patent Publication Number: US-2022233333-A1

Title: Surgical method and instrumentation assembly for positioning an ankle prosthesis

Description:
The present application claims priority to U.S. Provisional Application No. 62/129,593 filed Mar. 6, 2015 incorporated herein by reference. 
    
    
     The present invention concerns a surgical ankle repair method. The present invention also concerns a surgical instrumentation assembly for positioning an ankle prosthesis. 
     The ankle implants are generally positioned using the tibia as a reference, as disclosed in US-A-2013/0116797. A cutting block is attached to the tibia and aligned with the axis of the tibia, and resections of the talus are performed after having found the right foot position with respect to at least one rotational plane of the ankle. 
     The positioning of the resections of the talus may be challenging as the rotational plane of the talus is found by techniques whose accuracy can be improved. Inaccuracies in the positioning of the implants can result in excessive stresses on the bones and soft tissues around the implants, and may reduce longevity of the implants. 
     The aim of the invention is to provide a new surgical method which permits the physician to better position the prostheses with respect to the bones of the patient. 
     To this end, the invention concerns a surgical ankle repair method comprising the steps of: 
     a) providing an instrumentation assembly for positioning an ankle prosthesis, the instrumentation assembly including a talar alignment instrument and a cutting block, the talar alignment instrument comprising a front portion and two fins extending from the ends of the front portion, said fins being adapted to be positioned in gutters extending below a tibia of a patient and around the trochlea of a talus of the patient, each fin including a reference marker, the cutting block comprising a tibial alignment structure and a recess which engages a protrusion provided on the talar alignment instrument, 
     b) positioning the talar alignment instrument such that the fins are disposed in the gutters extending below the tibia and around the trochlea of the talus; 
     c) aligning the talar alignment instrument so that the fins are parallel to the rotational plane of the talus, perpendicular to the rotational axis of the talus, and so that the reference markers are aligned with a longitudinal axis of the tibia; 
     d) confirming alignment of the reference markers via imaging technology; 
     e) mechanically attaching the talar alignment instrument to the talus; 
     f) fastening the cutting block to the talar alignment instrument such that the recess engages the protrusion locked in a parallel orientation to the rotational plane of the talus; 
     g) rotating the talus such that the tibial alignment structure is in a parallel alignment to the longitudinal axis of the tibia, thereby correcting any varus or valgus deformity of the talus; 
     h) attaching the tibial alignment structure to the tibia; and 
     i) performing a first resection of the talus and several resections of the tibia using the cutting block. 
     Thanks to the invention, the resections of the tibia and the talus are performed using the talus as reference, resulting in better alignment and positioning of the implants. 
     According to further aspects of the invention which are advantageous but not compulsory, such a surgical method may incorporate one or several of the following features:
         The imaging technology is selected from the group consisting of X-ray, CT, and MR imaging.   The method comprises, after step i), a further step j) consisting in inserting, in at least one hole drilled in the talus at step e) for inserting screws adapted to mechanically attach the talar alignment instrument to the talus, a positioning element for positioning a cutting guide for performing a second resection of the talus.   The at least one resection performed on the talus at step i) is a posterior chamfer, whereas at step j) the cutting guide for performing the second resection is also positioned against the posterior chamfer.   The method comprises, after step j), a further step k) consisting in positioning, on the surface of the second resection, a cutting guide for performing a third resection of the talus, which forms with the second resection an anterior chamfer.   The talar alignment instrument is used to align a second cutting guide for performing a second resection of the talus.   The second cutting guide remains on the talus surface, the talar alignment instrument is removed and a third cutting guide is placed on the second cutting guide to perform a third resection of the talus which forms with the second resection an anterior chamfer.   At least one hole drilled in the talus at step e) for inserting screws adapted to mechanically attach the talar alignment instrument to the talus is used for drilling a hole destined to receive an anchoring peg of a talus implant.   The talar alignment instrument is mechanically attached to the talus using at least two screws.   The reference markers for the fins mark a direction perpendicular of the fins.
 
The invention also concerns a surgical ankle replacement method comprising the steps of:
   a) placing a talar alignment instrument on the talus,   b) positioning the talar alignment instrument on the talus   c) aligning a reference marker provided on the talar alignment instrument   d) mechanically attaching the talar alignment instrument to the talus,   e) fastening a cutting block to the talar alignment instrument,   f) locking a relative position of the cutting block and the tibia,   g) performing, using the cutting block, at least one resection of a lower surface of the tibia and at least one resection of a top surface of the talus.       

     According to further aspects of the invention which are advantageous but not compulsory, such a surgical replacement method may incorporate one or both of the following features:
         At step b) the talon alignment instrument is positioned relative to a rational plane of the talus and to a rational axis of the talus.   At step c) the reference marker allows matching of the instrument&#39;s axis and radii to the talus&#39;s radii and axis.       

     The invention also concerns a surgical instrumentation assembly for positioning an ankle prosthesis, the ankle prosthesis including a tibia implant and a talus implant, wherein the instrumentation assembly comprises:
         a talar alignment instrument adapted to be placed on a talus of a patient, and relative to the rotational plane of the talus, and centered on the rotational axis of the talus, and perpendicular to the rotational plane of the talus and mechanically attached to the talus,   a cutting block adapted to be fastened to the talar alignment instrument and locked with respect to the tibia.       

     According to further aspects of the invention which are advantageous but not compulsory, such a surgical instrumentation assembly may incorporate one or several of the following features:
         The talar alignment instrument comprises a front portion and two fins extending from the ends of the front portion, said fins being adapted to be positioned in gutters extending below the tibia and around the trochlea of the talus.   The front portion comprises holes for inserting screws for mechanically attaching the talar alignment instrument to the talus.   The front portion comprises a protruding portion adapted to be received in a recess of the cutting block, the recess and the protruding portion being configured to prevent relative displacement of the talar alignment instrument and the cutting block, and locking parallel to the rotational plane of the talus.   The recess and the protruding portion are complementary shaped.   The fins of the talar alignment instrument are provided with reference markers adapted to mark a direction perpendicular to the fins, and adapted to be aligned with the longitudinal axis of the tibia, and aligned to the rotational axis of the talus.   The reference markers are elongated slots.   The cutting block comprises a tibial alignment structure adapted to be aligned with the longitudinal axis of the tibia and mechanically attached to the tibia.   The cutting block is configured to permit the cutting of at least one surface or hole on the top surface of the talus and cutting of at least one surface or hole in the distal portion of the tibia.   The assembly further comprises one or several cutting guides configured to permit the cutting of additional surfaces or holes on the top surface of the talus, whereas said cutting guides are adapted to be positioned against prior cut surfaces or holes.   At least one of the cutting guides for cutting additional surfaces or holes comprises at least one positioning shape adapted to be positioned against a screw inserted in a hole previously drilled in the talus for inserting a screw for mechanically attaching the talar alignment instrument to the talus.   At least one of the cutting guides for the cutting additional surfaces comprises of at least one positioning shape adapted to be positioned against the talar alignment instrument attached to the talus.       

    
    
     
       The invention will now be explained in reference to the following figures, as an illustrative example. In the annexed figures: 
         FIG. 1  is a perspective view of a talar alignment instrument belonging to an instrumentation assembly according to the invention; 
         FIG. 2  is a perspective view of the positioning of the talar alignment instrument of  FIG. 1  on a talus; 
         FIG. 3  is a side view of the positioning of the talar alignment instrument of  FIG. 1  with respect to the talus and the tibia of a patient; 
         FIG. 4  is a front view of the positioning of the talar alignment instrument of  FIG. 1  on a talus; 
         FIG. 5  is a perspective view of a cutting block belonging to an instrumentation assembly according to the invention and a talar alignment instrument positioned on a talus; 
         FIG. 6  is a front view of the cutting block of  FIG. 5  positioned with respect to a talus and a tibia; 
         FIG. 7  is a side view of the talar alignment instrument and the cutting block during cutting of resections of the tibia and the talus; 
         FIG. 8  is a perspective view of an ankle after resections have been performed; 
         FIGS. 9 and 10  are perspective views similar to  FIG. 8 , during resection of other portions of the talus; 
         FIG. 11  is a front view of an ankle articulation equipped with tibia and talus implants shown in ghost lines; 
         FIG. 12  is a side view of the ankle articulation, tibia and talus implants of  FIG. 11 ; 
         FIG. 13  is a view similar to  FIG. 11  showing only the tibial implant. 
     
    
    
     A surgical method and an instrumentation assembly are described below for replacing an ankle articulation on a patient, by implanting tibia and talus prostheses. The method and the instruments described below can be used for implanting ankle prostheses having a wide variety of structures, for example having tibia and/or talus implants that are constituted by a plurality of parts assembled to one another, and that may be made of metal, polymer, ceramic, composite, and a variety of other materials. 
     For convenience, the description below describes directions relative to the bones of an ankle in their anatomical position, the terms posterior or rear, anterior, front, right, left, upper, lower, etc. should be understood relative to the ankle of a patient standing on a substantially horizontal surface and viewed from the ankle. 
     Initially, the bones of the ankle of the patient which include a talus T and a tibia B, need to be prepared by performing resections for receiving the implants. 
     The instrumentation assembly comprises a talar alignment instrument  2  represented in  FIG. 1 . This talar alignment instrument  2  is adapted to be placed on the talus T during a first step of the surgical method according to the invention. The talus alignment instrument  2  comprises a front portion  20  and two fins  22  and  24  extending from the lateral most portions or ends  22   a  of front portion  20  in a substantially perpendicular direction. In the example, the fins  22  and  24  are independent parts which are fixed to the front portion  20 , for example, by screws  26 . Advantageously, the fins  22  and  24  may be made of an elastic metal, such as nitinol, so as to provide a flexibility suitable for adaptation of the talar alignment instrument to various ankle anatomies. 
     The resections performed on the talus T and the tibia B are performed using as a reference the talar alignment instrument  2 , which is fixed to the talus T and positioned with respect to the rotational plane P 1 , and the talus T. The rotational plane P 1  is best defined by the interface between the tibia, fibula, and talus. Since the tibia and fibular share this interface, the talus is the singular bone that best defines this surface. This part of the talus is called the trochlea, and where the talar alignment instrument directly attaches. This permits to provide better accuracy for the positioning of the implants and therefore to obtain a better comfort for the patient and a longer longevity of the implants. 
     The use of the talus T as reference for the bone resections also permits to determine the size of the implants. The trochlea of the talus as described above, also defines the width of the implant. Since the talar alignment instrument attaches directly to the trochlea, the width is determined accurately and therefore the size of the implant is accurately selected. 
     According to a non-shown embodiment, the talar alignment instrument  2  may be a monolithic or unitary structure, with the fins  22  and  24  and front portion  20  comprising 1 piece. 
     The fins  22  and  24  are adapted to be positioned in gutters G 1  and G 2  of talus T which extend around a trochlea T 1  of the talus T, which is a globally cylindrical portion of the talus T. The gutters G 1  and G 2  extend below a portion of a tibia B and a portion of a fibula F. The gutter G 1  is the vertical joint spaces comprised of the lateral side of the trochlea and inner side of the fibula. The gutter G 2  is the vertical joint space comprised of the medial side of the trochlea and inner side of tibia&#39;s medial malleolus. The tibia B, the fibula F and the talus T together form the ankle articulation of a patient. 
     A second step of the surgical method consists in positioning the talus alignment instrument  2  so that the fins  22  and  24  are substantially parallel to a rotational plane P 1  of the talus T. The rotational plane P 1  is the plane defined by the rotation of the talus T with respect to the tibia B around a rotational axis X 1  which is substantially parallel to a horizontal surface on which the patient is virtually standing, and which extends along a right-left direction of the ankle. The fins  22  and  24  have a substantially planar shape perpendicular to rotational axis X 1 . The fins  22  and  24  are also positioned in alignment of rotational axis X 1 . 
     A further step of the surgical method, which is represented on  FIG. 3 , consists in aligning reference markers provided on the talar alignment instrument  2  with a longitudinal axis XB (illustrated in  FIG. 6 ) of the tibia B. In the example shown, the reference markers are elongated slots, which may be holes  220  and  240  which are provided on fins  22  and  24  and adapted to mark a direction perpendicular to a longitudinal axis X 22  of the fins  22  and  24 . The alignment of the reference markers  220  and  240  is checked by imaging using for example X-rays, magnetic resonance imaging (MRI) or computed tomography (CT). 
     According to a non-shown embodiment, the reference markers may be other geometrically shaped holes allowing visualization and alignment utilizing, for example, X-rays, CT or MRI of the fins  22  and  24  to obtain perpendicular images to the talar alignment instrument  2 . Alternatively, the reference markers may also be protrusions or recesses adapted to be visible in the above-mentioned imaging techniques. 
     The talar alignment instrument  2  is then mechanically attached to the talus T, using at least two screws  3  represented on  FIGS. 8 and 9 . The screws  3  are inserted through holes  30  provided in the front portion  20  and in the holes drilled in the talus T. 
     During the positioning and attachment steps of the talar alignment instrument  2 , the instrument  2  is handled or connected to a rod  4  having an end adapted to be inserted in a protruding portion  32  of front portion  20 . The protruding portion  32  comprises an inner recess  320  having a hexagonal shape complementary with the distal end of the rod  4 , which prevents rotation of the instrument  2  around the longitudinal axis of the rod  4 . 
     According to a non-shown embodiment of the invention, instead of having a hexagonal shape, the inner recess  320  may present any other different shape adapted to prevent relative rotation between the rod  4  and the talar alignment instrument  2 , for example a square shape, an ovoid shape, etc. 
     The instrumentation assembly also includes a cutting block  5 , represented on  FIG. 5 . The cutting block  5  comprises slots  50  for passing cutting instruments which perform resections of a top surface T 2  of the talus T and a lower surface B 1  of the tibia B, as it will be described later. 
     The slots  50  are provided on a lower portion  55  of the cutting block  5 . This lower portion  55  also includes a recess  54  adapted to receive the protruding portion  32  of the talar alignment instrument  2 . The recess  54  and the protruding portion  32  are therefore complementary shaped in order to prevent relative rotation between the cutting block  5  and the talar alignment instrument  2 . In the example, recess  54  and protruding portion  32  have a parallelepiped shape. In a non-shown embodiment, the shape of recess  54  and protruding portion  32  may be of any other shape adapted to prevent relative rotation. 
     The cutting block  5  also includes a tibial alignment structure  56  which extends substantially vertically from an upper portion  52  of the cutting block  5 . The tibial alignment structure  56  is terminated by an upper alignment device  560 . 
     In a further step, the cutting block  5  is attached to the talar alignment instrument  2  by mounting the recess  54  on the protruding portion  32  and by inserting a screw  7  through the recess  54  and in a threaded bore  322  provided in protruding portion  32 . 
     Once the cutting block  5  is fastened to the talar alignment instrument  2 , the talus T is rotated with respect to the tibia B by moving the foot of the patient so that the tibial alignment structure  56  is in parallel alignment to the longitudinal axis XB of the tibia B, as shown on  FIG. 6 . In this step, the talus T is rotated in a plane perpendicular to the rotational plane P 1  and comprising the longitudinal axis XB. By aligning the tibial alignment structure  56  with the longitudinal axis XB, varus or valgus deformities of the talus T are corrected. 
     Following the varus or valgus deformities correction, the cutting block  5  and the tibia B are mechanically attached so that the relative position of the talus T and the tibia B is locked in the subsequent steps of the surgical method. Several holes are drilled in the tibia B using drilling guides  58  provided on the lower portion  55  and on the tibial alignment structure  56 . Pins  8  are inserted into the drilling guides  58  and in the holes drilled in the tibia B, as shown on  FIG. 7 , so that the cutting block  5  cannot move with respect to the tibia B. The alignment device  560  is also attached to a non-shown upper portion of the tibia B using non-shown attaching means. 
     Once the cutting block  5  is fixed with respect to the talus T and the tibia B, resections of the talus T and the tibia B can be performed so as to prepare the bones of the patient for the mounting of the ankle replacement implants. A top portion of the talus T is resected by cutting a posterior chamfer  10  represented on  FIG. 8 . This resection is performed using a saw blade  11  inserted in an angled slot of lower portion  55 . 
     As represented on  FIG. 8 , resections of the lower surface B 1  of the tibia B are performed by non-shown cutting blades, so as to form a square-shaped lodgment B 2  comprising flat surfaces adapted to receive a tibial implant. A cylindrical recess  13  is drilled in the tibia B using a drill bit  15  inserted into a drilling guide  60  of cutting block  5 . The recess  13  is destined to receive an anchoring keel of a tibial implant. A vertical hole  13 B is also cut for linking the cylindrical recess  13  to the outer resected surface of the lodgment B 2 . The cutting block  5  is then removed. It should be noted that no additional holes are required to attach the cutting block to the talus, which may be referred to as “bonus holes”. In reducing the number of holes created in the bone, bone loss is minimized. 
     In a further step of the surgical method, an anterior chamfer  17  is resected on the top surface of the talus T. This anterior chamfer  17 , which is visible on  FIG. 12 , is obtained in two consecutive operations, shown in  FIGS. 9 and 10 . 
     In  FIG. 9 , a second cutting guide  19  of the instrumentation assembly, comprising a backwards extending portion  190  having a planar lower surface, is positioned against the posterior chamfer  10 . The second cutting guide  19  also includes a front portion  192  which comprises a plate  192   a  adapted to be positioned against protruding portion  32  thanks to non-shown complementary shaped surfaces. The front portion  192  is extended by a rod  194  for handling the cutting guide  19 . 
     As an optional feature, the second cutting guide  19  comprises two lodgments  196  which define cylindrical slots for passing two pins  21 , which are inserted in non-shown holes drilled in the talus T. The pins  21  permit to further lock the position of the second cutting guide  19  with respect to the talus T. 
     The second cutting guide  19  comprises several cylindrically shaped lodgments  198  adapted to receive a drilling bit  23  used to cut a first portion  17   a , visible on  FIG. 10  of the anterior chamfer  17 . As shown on  FIG. 9 , the first portion  17   a  of the anterior chamfer  17  is obtained by five adjacent consecutive drilling operations. As an alternative, the first portion  17   a  of the anterior chamfer  17  may be obtained using different drilling or cutting means. 
     On  FIG. 10 , a second portion  17   b  of the anterior chamfer  17  is resected. During this operation, the second cutting guide  19  is kept into place, the talar alignment instrument  2  is dismounted, leaving open a hole  100  of the talus T, in which one of the screws  3  was present to attach the talar alignment instrument  2  to the talus T. The front portion  192  of the second cutting guide  19  is removable from a main portion of the second cutting guide  19 , which comprises the lodgments  198 . This front portion  192  is removed and replaced by a third cutting guide  9  of the instrumentation assembly. The third cutting guide  9  comprises five adjacent lodgments  90  adapted to receive a drilling bit  25 , which could be the same as drilling bit  23 , and which is adapted to drill the second portion  17   b  of the entire chamfer  17  in five drilling operations. The third cutting guide  9  also comprises, extending besides lodgments  90 , a positioning block  92  adapted to be inserted in the lodgments  198  of the second cutting guide  19  to lock in position the third cutting guide  9  with respect to the second cutting guide  19 . The positioning block  92  is inserted in the second cutting guide  19 , a lower end of the positioning block  92  is in contact with the first portion  17   a  of the anterior chamfer  17 . 
     When the second portion  17   b  is obtained, the resection of the anterior chamfer  17  is complete and a talus implant  16  can be mounted on the talus T, as shown on  FIGS. 11 and 12 . The talus implant  16  comprises an articulation surface  160 , and two anchoring pegs  162 , which are inserted in the holes  100  in which the screws  3  for fixing the talar alignment instrument  2  were inserted. The holes  100  may be prepared for the reception of the pegs  162  by a drilling at the diameter of the pegs  162 . 
     A tibia implant  18  is inserted in the recess  13  prepared in the tibia B. Suitable tibia implants include, for example, Salto Talaris™ Total Ankle Prosthesis (manufactured by Tornier), INFINITY® total ankle system (manufactured by INBONE), Scandinavian Total Ankle Replacement (START™ Ankle) (manufactured by Stryker), Integra® Total Ankle Prosthesis (manufactured by Integra), Zenith™ Total Ankle Replacement (manufactured by Corin), BOX® Total Ankle Replacement (manufactured by MatOrtho®). 
     The holes  100  which are drilled for receiving screws  3  for attaching talus alignment instrument  2  to the talus T are used to receive anchoring pegs  162  of the talus implant  16 . This permits the physician to reduce the number of holes drilled in the bones during the surgical procedure and which are left unused after the ankle replacement. 
     According to a non-shown embodiment of the invention, after the cutting of the posterior chamfer  10 , the talar alignment instrument  2  may be removed. In such a case, the holes  30  of the front portion  20  may be provided with a lateral getaway formed by a slot so that the talar alignment instrument  2  can be removed without dismounting the screws  3 , which are left inserted in the talus T. 
     To cut the first portion  17   a  of the anterior chamfer  17 , a cutting guide similar to the cutting guide  19  is positioned against the screws  3  and against the posterior chamfer  10 . 
     Once the first portion  17   a  is drilled, the cutting guide is removed and a second cutting guide is positioned against the posterior chamfer  10  and the first portion  17   a  of the anterior chamfer  17 . The second portion  17   b  of the anterior chamfer  17  is then drilled. Other embodiments are envisioned and within the scope of this application including patient specific instruments and implants. Ankle prosthesis instruments including tibial and talar guides may be prepared or manufactured based on patient specific anatomical data obtained using imaging technology including but not limited to X-ray, CT, and MRI imaging. In one embodiment, a physician may use anatomical imaging data of a patient and transmit this anatomical data to an instrument/implant manufacturer, wherein the instrument/implant manufacturer can create an instrument and/or implant which is designed based on the patient&#39;s specific anatomical data. Talar alignment instruments, cutting guides, cutting blocks, screws, and jigs may be manufactured with surfaces, angles, orientations, and structures which conform or complement the specific anatomy of the patient. For example, cutting guides having slots and (pin) holes for cutting the talus and aligning the ankle may include geometries conforming to anatomical surfaces or regions of the tibia, talus, other anatomical ankle bones, tendons, muscles, and markers. 
     In one particular embodiment, the talar alignment instrument  2  of the present disclosure may be created using patient specific anatomical data. More specifically, images of a patient may be obtained using MRI, X-ray, CT and combinations thereof. Images/scans may be represented as a virtual model of the patient&#39;s anatomy whereupon a physician may create and size patient specific implants and instruments. Alternatively images and/or scans of a patient&#39;s anatomy may be sent to an implant/instrument manufacturer whereupon a custom designed, or patient specific implant/instrument may be created. Specifically, scans of the hard and soft tissues can be used to create custom instrumentation, tools and implants for total ankle prostheses, including, but not limited to, talar alignment instruments, and cutting blocks and jigs having cutting slots and drill guides which are specific to the patient&#39;s anatomy/geometry. With regards to the current invention, the talar alignment instrument may include fins corresponding to patient anatomy including the gutters on the trochlea and taking into account any varus and valgus deformities. 
     In another embodiment, patient specific instruments/implants can be created by first taking into account a patient&#39;s corrected anatomy and then building the implants, instruments and tools to correspond to the corrected anatomy. In more detail, a surgeon can use patient anatomical images, such as x-ray and CT images and load those images into 3-D CAD software and correct a varus or valgus deformity first in a 3-D software, next a patient specific cutting jig or block is generated based on the corrected deformity. Once the block is manufactured, the surgeon may secure the patient specific block when the ankle is plantar flexed, enabling the surgeon to attach the patient specific cutting block to the talus only. The surgeon can correct the varus or valgus deformity by rotating the cutting block left and right, or medially and laterally. Next, the surgeon may then align the cutting block with the longitudinal axis of the tibia and place a pin in the tibia to attach the patient specific cutting block to the tibia. It should be noted that the aforementioned surgical steps are all performed while the ankle is plantar flexed, exposing maximum surface area of the talus to accurately position and attach the talus. The invention also concerns a kit for positioning an ankle prosthesis including a talar alignment instrument and a cutting block, the talar alignment instrument comprising a front portion and two fins extending from the ends of the front portion, said fins being adapted to be positioned in gutters extending below a tibia of a patient and around the trochlea of a talus of the patient, each fin including a reference marker of a direction perpendicular to the fins, the cutting block comprising a tibial alignment structure and a recess which engages a protrusion provided on the talar alignment instrument. 
     The invention also concerns a surgical ankle repair method comprising, before the step of providing an instrumentation assembly, a first step consisting in performing MRI, CT or X-ray imaging of the anatomy of a patient, and wherein the step of providing an instrumentation assembly is realized on the basis of the anatomical data of the patient provided by said imaging. More specifically, the imaging data may be used to design a talar alignment instrument adapted to be placed on a talus of a patient, and relative to the rotational plane of the talus, and centered on the rotational axis of the talus, and perpendicular to the rotational plane of the talus and mechanically attached to the talus, and a cutting block adapted to be fastened to the talar alignment instrument and locked with respect to the tibia. 
     In certain embodiments, the imaging data collected can be used by the surgeon in planning procedural steps, including, but not limited to, planning surgical cuts or bone and tissue resection. 
     The technical features of the above-described embodiment and variants can be combined to form new embodiments of the invention.