Patent Description:
An ankle joint may become severely damaged and painful due to arthritis from prior ankle surgery, bone fracture, infection, osteoarthritis, post-traumatic osteoarthritis or rheumatoid arthritis, for example. Options for treating the injured ankle have included antiinflammatory and pain medications, braces, physical therapy, amputation, joint arthrodesis, and total ankle replacement.

Current ankle joint replacement options include preparing the distal end of the tibia by drilling through the calcaneus and the talus from the bottom of the foot to access the distal end of the tibia to ream the tibial intramedullary canal. Such approaches require an additional incision in the heel. The patient's recovery time can be extended and can delay the weight-bearing time after the surgery.

A recent improved ankle joint replacement procedure involves approaching the ankle joint space with a broach from the anterior side and preparing the intramedullary canal of the tibia manually. Furthermore, <CIT> discloses a geared instrument for stem reaming and removal. This geared instrument may be sized and configured to facilitate an ankle resectioning and/or replacement: the geared instrument is configured to fit through an anterior incision formed during an ankle resectioning and/or replacement. The use of the geared instrument eliminates the need for additional incisions providing axial access to the tibial canal. Instead, a housing of the geared instrument fits within the ankle joint through the anterior incision and allows a channel to be formed in the tibial canal from the anterior incision. This geared instrument generally comprises a handle configured to rotate about a first axis. The handle is received in the aforementioned housing and couples to a handle gear that is coupled to a translation gear located within the housing. A stem extends longitudinally through the translation gear that is configured to translate rotation of the handle about the first axis to rotation of the stem about a second axis that may be perpendicular to the first axis. The stem comprises a modular connection configured to receive a modular head, such as a drill bit.

An object of the invention is a power driver adapter configured for cutting into an intramedullary canal of a tibia, as defined in claim <NUM>. Another objet of the invention is a surgical instrument kit as defined in claim <NUM>.

Disclosed is a method of preparing an intramedullary canal in a tibia for receiving a tibial implant. In some embodiments, the method comprises (a) resecting the distal end of the tibia and forming a resected joint space for the tibial implant, wherein the joint space comprises a tibial resection surface at the distal end of the tibia and is open at the anterior side; (b) positioning a power driver, equipped with a cutting tool bit, into the joint space from the anterior side, wherein the cutting tool bit is aimed toward the intramedullary canal of the tibia; and (c) cutting into the intramedullary canal using the power driver to form a tibial hole or a tibial cavity. The power driver can be used in conjunction with a guide assembly that can assist alignment of the cutting tool bit.

According to another aspect of the present disclosure, the method of preparing an intramedullary canal in a tibia for receiving a tibial implant can involve positioning the power driver, equipped with a cutting tool bit, into the joint space from the posterior side.

According to another aspect of the present disclosure, the method of preparing an intramedullary canal in a tibia for receiving a tibial implant can involve positioning the power driver, equipped with a cutting tool bit, into the joint space from the lateral side.

Also disclosed is a power driver adapter configured for cutting into an intramedullary canal of a tibia. The power driver adapter comprises an elongated body having a driving end, a cutting tool bit receiving end, and a longitudinal axis. The driving end comprises a drive shaft coaxially located with the longitudinal axis and is configured to mate with a power delivering unit that rotates the drive shaft coaxially about the longitudinal axis. The cutting tool bit receiving end comprises a cutting tool bit receiving base that is configured for engaging with a cutting tool bit and rotates the cutting tool bit for cutting action, where the cutting tool receiving base rotates with a rotational axis that is orthogonal to the longitudinal axis of the elongated body and translates superiorly and inferiorly. The elongated body comprises a series of gears connecting the drive shaft to the cutting tool bit receiving end. The series of gears are configured in an arrangement that converts the coaxial rotation of the drive shaft to the rotation and translation of the cutting tool bit receiving base.

A surgical instrument kit that includes the power driver adapter is also disclosed.

The inventive concepts of the present disclosure will be described in more detail in conjunction with the following drawing figures. The structures in the drawing figures are illustrated schematically and are not intended to show actual dimensions.

This description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. The drawing figures are not necessarily to scale and certain features may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness. In the description, relative terms such as "horizontal," "vertical," "up," "down," "top" and "bottom" as well as derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms including "inwardly" versus "outwardly," "longitudinal" versus "lateral" and the like are to be interpreted relative to one another or relative to an axis of elongation, or an axis or center of rotation, as appropriate. Terms concerning attachments, coupling and the like, such as "connected" and "interconnected," refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. When only a single machine is illustrated, the term "machine" shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. The term "operatively connected" is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. In the claims, means-plus-function clauses, if used, are intended to cover the structures described, suggested, or rendered obvious by the written description or drawings for performing the recited function, including not only structural equivalents but also equivalent structures.

Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus, specific orientations be required, unless specified as such. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

<FIG> illustrates an anatomic view of an ankle joint <NUM>. The ankle joint <NUM> comprises a talus <NUM> in contact with a tibia <NUM> and a fibula (not labelled). A calcaneus <NUM> is located adjacent to the talus <NUM>. In total ankle replacements, the talus <NUM> and the tibia <NUM> may be resected, or cut, to allow insertion of a talar implant and a tibial implant.

A total ankle replacement system can include a talar implant <NUM> and a tibial implant <NUM>. The talar implant <NUM> can include an articulation surface <NUM> configured to mimic a natural articulation surface of the talus <NUM>. The talar implant <NUM> can have a stem <NUM> that extends into the talus <NUM> to anchor the talar implant <NUM>. A tibial implant <NUM> can be sized and configured for installation into the tibia <NUM>. The tibial implant <NUM> can include a body comprising an articulation surface <NUM> configured to mimic a natural articulation of the tibia <NUM> and a tibial stem <NUM> extending into the intramedullary canal of the tibia <NUM> to anchor the tibial implant <NUM>. The articulation surfaces <NUM>, <NUM> of the respective implants <NUM>, <NUM> replace the natural ankle joint surfaces, which are removed, to restore a range of motion that mimics the natural joint.

<FIG> is an illustration of a resected tibial end 16a of the tibia <NUM> in a human ankle showing the resected joint space <NUM>.

Referring to <FIG>, and <FIG>, a power driver <NUM> configured for cutting into an intramedullary canal of a tibia is disclosed. The power driver <NUM> comprises a power driver unit <NUM> for hand-held operation and a power driver adapter <NUM>.

Preferably, the power driver unit <NUM> is a handheld drill-like power tool that can rotatably drive the power driver adapter <NUM> and comprises a chuck <NUM> that engages the drive shaft <NUM> of the power driver adapter <NUM>.

As shown in <FIG>, and <FIG>, the power driver adapter <NUM> comprises an elongated body <NUM> having a first end <NUM>, a second portion <NUM>, and a longitudinal axis L. The first end <NUM> is configured as a driving end and has a drive shaft <NUM> coaxially located with the longitudinal axis L and configured to engage with the power driver unit <NUM> that rotates the drive shaft <NUM> coaxially about the longitudinal axis L. The second portion <NUM> is configured as a cutting tool bit receiving portion. The cutting tool bit receiving portion <NUM> is configured to engage with a cutting tool bit <NUM> and rotates the cutting tool bit <NUM> for a cutting action. For example, as shown in <FIG> and <FIG>, the cutting tool bit receiving portion <NUM> can be provided with a cutting tool bit receiving base <NUM> that is configured to receive the cutting tool bit <NUM> and securely hold the bit. The cutting tool bit receiving base <NUM> is configured to rotate about a rotational axis R that is orthogonal to the longitudinal axis L.

The cutting tool bit receiving base <NUM> in the illustrated embodiment is a disc-like piece that comprises a threaded hole 232a into which the cutting tool bit <NUM> can thread into. The cutting tool bit <NUM> that is configured for attaching to the cutting tool bit receiving base <NUM> comprises a threaded base stem (not shown). In some other embodiments, the cutting tool bit receiving base <NUM> can comprise a socket hole instead for receiving the cutting tool bit <NUM>. The socket hole can have a square hole configuration or a hexagonal hole configuration and can have a spring-loaded detent system for holding the cutting tool bit <NUM>. These are just examples and there are other suitable configurations for engaging the cutting tool bit receiving base <NUM> with the cutting tool bit <NUM> that would be readily understood by those of ordinary skill in the art.

The elongated body <NUM> comprises a first portion 210a and a second portion 210b. The elongated body <NUM> comprises a slip clutch in the first portion 210a and a series of gears in the second portion 210b that connect the drive shaft <NUM> to the cutting tool bit receiving portion <NUM>. The series of gears are configured in an arrangement that converts the coaxial rotation of the drive shaft <NUM> to the rotation of the cutting tool bit receiving base <NUM>. An example of such series of gears is shown in the cross-sectional view of the elongated body <NUM> in <FIG>.

The first portion 210a comprises a drive shaft extension piece 222a that is connected to the drive shaft <NUM> by a slip-clutch mechanism <NUM>. When the cutting tool bit receiving portion <NUM> reaches the bottom (the START) or the top (FINISH) position against the housing of the second portion 210b, the slip clutch <NUM> allows the drive shaft <NUM> to continue to be turned by the power driver <NUM> while the drive shaft extension piece 222a (and, in turn, the spur gears <NUM>) stop turning. The second portion 210b comprises a group of spur gears <NUM> for transferring the rotational motion to the cutting tool bit receiving base <NUM>. Between the group of spur gears <NUM> and the drive shaft 222a, a bevel gear arrangement <NUM> is provided to convert the coaxial rotation motion of the drive shaft <NUM>, 222a, into the orthogonally oriented rotation motion of the cutting tool bit receiving base <NUM>.

In some embodiments, the cutting tool bit receiving base <NUM> is a spur gear and the cutting tool receiving portion <NUM> can comprise one or more additional spur gears <NUM> that connects the cutting tool bit receiving base <NUM> with the group of spur gears <NUM>. The cutting tool bit receiving base <NUM> and the additional spur gears in the group of spur gears <NUM> have a short or low profile and have a disc-like shape, which allows the cutting tool bit receiving portion <NUM> to maintain a low profile for positioning the cutting tool bit receiving portion <NUM> into the resected joint space <NUM>. The last spur gear 227a among the group of spur gears <NUM> engages with the first spur gear 229a among the additional spur gears <NUM>.

The cutting tool bit <NUM> can be one of many types of cutting tool bits that may be used in orthopedic procedures. In some embodiments of the power driver adapter <NUM>, the cutting tool bit <NUM> is a reamer bit.

In some embodiments of the power driver adapter <NUM>, the cutting tool bit receiving portion <NUM> can be configured to translate linearly along directions that are coaxial to the rotational axis R of the cutting tool bit <NUM> and orthogonal to the longitudinal axis L. The directions of the linear translation motion are illustrated by the arrows T1 and T2 in <FIG>. The illustration of <FIG> is a sectional view seen from the side. Therefore, when the power driver adapter <NUM> is in operational use in the resected joint space <NUM>, the arrow T1 represents the anatomical superior direction and the arrow T2 represents the anatomical inferior direction.

In some embodiments, in addition to the group of spur gears <NUM>, the second portion 210b further comprises a helical thread arrangement that enables the linear translation of the cutting tool bit receiving portion <NUM>. In the exemplary structure shown in <FIG>, this helical thread arrangement comprises a helical threaded stem <NUM> and the first spur gear 229a among the additional spur gears <NUM> in the cutting tool bit receiving portion <NUM>. The first spur gear 229a comprises a helical threaded hole in its rotational center that engages the helical threaded stem <NUM>, which extends through the helical threaded hole. The helical threaded stem <NUM> does not rotate. When the cutting tool bit <NUM> is being rotated for a cutting action, as the first spur gear 229a rotates, its helical threaded hole cooperates with the helical thread on the helical threaded stem <NUM> and translates along the length of the helical threaded stem <NUM>, thus, moving the whole cutting tool bit receiving portion <NUM> along the length of the helical threaded stem <NUM>.

Depending on the rotational direction; the helical threads on the first spur gear 229a and the helical threaded stem <NUM> are appropriately handed (i.e., right handed or left handed) so that the first spur gear 229a, and hence the cutting tool bit receiving portion <NUM>, translates in the direction T2 indicated by the arrow in <FIG> when the cutting tool bit <NUM> is being turned or driven in the cutting direction. Conversely, when the cutting procedure is completed, the power driving unit <NUM> is reversed and the cutting tool bit <NUM> is rotated in the opposite direction, the first spur gear 229a and the cutting tool receiving portion <NUM> will translate along the helical threaded stem <NUM> in the opposite direction T1.

When the power driver adapter <NUM> is used for reaming the distal end of a tibia, for example, the power driver adapter <NUM> is in position such that the cutting tool bit <NUM> is positioned and aimed toward the intramedullary canal of the tibia, the cutting tool receiving portion <NUM> would be in its START position, i.e., with the cutting tool receiving portion <NUM> at its most inferior position. This START configuration is shown in <FIG>. In <FIG>, one can tell that the cutting tool receiving portion <NUM> is in the START position because it is on the opposite side of the alignment pins <NUM>. The function of the alignment pins <NUM> are described below in conjunction with <FIG>. When the power driver unit <NUM> is turned on to its cutting mode, as the cutting tool bit <NUM> turns in the cutting direction, the cutting tool holding portion <NUM> translates in the direction T2. This enables the cutting tool bit <NUM> to be driven into the intramedullary canal of the tibia without moving the whole power driver unit <NUM> and the power driver adapter <NUM>. While the power driver unit <NUM> and the power driver adapter <NUM> assembly are being held stationary, the cutting tool bit <NUM> will automatically be driven into the intramedullary canal by the translation motion of the cutting tool bit receiving portion <NUM>.

Referring to <FIG>, <FIG>, and <FIG>, in some embodiments, the power driver adapter <NUM> can be used in conjunction with a guide assembly <NUM> that can assist with positioning and alignment of the power driver adapter <NUM> in the resected joint space <NUM> during the procedure of preparing the intramedullary canal of the tibia. The guide assembly <NUM> comprises a guide portion <NUM> configured for attaching to the resected surface at a distal end of the tibia, wherein the guide portion comprises a hole <NUM> for receiving and allowing the cutting tool bit <NUM> to extend therethrough. The guide assembly <NUM> also includes a guide head portion <NUM> extending in the proximal direction from the guide portion <NUM> and configured for attaching to the anterior side of the tibia as shown in <FIG>.

The power driver adapter <NUM> and the guide head portion <NUM> are configured to properly align and position the cutting tool bit <NUM> held in the power driver adapter <NUM> for cutting into the intramedullary canal of the tibia. The power driver adapter <NUM> can comprise of one or more alignment pins and the guide head portion <NUM> can comprise of one or more corresponding alignment slots for receiving the alignment pins to align the position of the power driver adapter <NUM>.

In the exemplary embodiment illustrated in <FIG>, the power driver adapter <NUM> comprises two alignment pins <NUM> and the guide head portion <NUM> comprises corresponding two alignment slots <NUM> for receiving the alignment pins <NUM>. After inserting the cutting tool bit receiving portion <NUM> of the power driver adapter <NUM> into the joint space <NUM> from the anterior side, the two alignment pins <NUM> are inserted into the corresponding alignment slots <NUM> on the guide head portion <NUM>. The power driver adapter <NUM> is oriented so that the cutting tool bit <NUM> is held in the cutting tool bit receiving portion <NUM> and positioned at the distal end of the resected tibia aimed toward the intramedullary canal of the tibia and ready to cut into the intramedullary canal of the tibia. In some embodiments, the alignment slots <NUM> are shaped and sized so that the alignment pins <NUM> and the alignment slots <NUM> establish a slip-fit engagement, which can help hold the power driver adapter <NUM> assembly securely in position during the cutting procedure. This arrangement would look very much like the ones illustrated in <FIG> and <FIG> except for the fact that <FIG> and <FIG> actually shows the arrangement at the end of the tibial intramedullary canal preparation procedure.

In use, after the guide assembly <NUM> is positioned in the resected joint space <NUM> as shown in <FIG>, the guide assembly <NUM> can be secured to the tibia by employing one or more fixation pins, such as k-wires or Steinmann pins. The guide head portion <NUM> can be provided with one or more holes extending therethrough for receiving such fixation pins. In the example shown in <FIG>, the guide head portion <NUM> is provided with a plurality of holes <NUM>; fixation pins <NUM> are shown inserted therethrough securing the guide assembly <NUM> to the tibia <NUM>.

In some embodiments, the power driver adapter <NUM> can be aligned within the joint space <NUM> without the use of the alignment guide <NUM>. For example, the power driver adapter <NUM> can be configured with an alignment arms <NUM> like the ones shown in <FIG> where the alignment arms <NUM> and the alignment pins <NUM> are radiopaque. The power driver adapter <NUM> can be inserted into the joint space <NUM> and viewed under a fluoroscopy to align the cutting tool bit <NUM>. In some embodiments, the power driver adapter <NUM> can be made of radiolucent material and provided with radiopaque markers (a bullseye, for example) for alignment cues.

According to another aspect of the present disclosure, a surgical instrument kit is disclosed. The surgical instrument kit comprises a power driver adapter <NUM> configured for cutting into an intramedullary canal of a tibia, and one or more bone cutting tool bits (e.g. one or more reaming bits <NUM>). The structure of the power driver adapter <NUM> is as described above. In some embodiments, the surgical instrument kit can also comprise a guide assembly <NUM> whose structure is as described above.

According to another aspect of the present disclosure, some methods for preparing the intramedullary canal in a tibia for receiving a tibial implant are disclosed. According to some embodiments, the flowchart 1000a in <FIG> in conjunction with <FIG> illustrates an example of such a method where the power driver adapter <NUM> equipped with a cutting tool bit <NUM> approaches the resected joint space <NUM> of an ankle from the anterior side for preparing the intramedullary canal in the distal end of the tibia for receiving a tibial implant according to an embodiment. The method comprises resecting the distal end of the tibia and forming a resected joint space <NUM> for receiving the tibial implant, where the joint space comprises a tibial resection surface at the distal end of the tibia and is open at the anterior side, see step <NUM>. If necessary, the proximal end of the talus may also need to be resected to properly form the resected joint space <NUM>. Then, a power driver unit <NUM> with a power driver adapter <NUM> equipped with a cutting tool bit <NUM> is positioned into the joint space <NUM> from the anterior side, where the cutting tool bit <NUM> is aimed toward the intramedullary canal of the tibia, see step <NUM>. Next, the power driver unit <NUM> is turned on to drive the cutting tool bit <NUM> to cut into the intramedullary canal, see step <NUM>.

In some embodiments of the method, cutting into the intramedullary canal forms a void or a tibial cavity extending into the intramedullary canal for receiving a tibial stem or a tibial extension of an ankle replacement implant.

In the arrangement shown in <FIG>, an embodiment of the power driver adapter <NUM> that is provided with a pair of alignment arms <NUM> is shown. The alignment arms <NUM> assist with aligning the trajectory of the cutting tool bit <NUM> as the power driver adapter <NUM> is positioned into the resected joint space <NUM>. The alignment arms <NUM> extend out from the power driver adapter <NUM> and have end portions <NUM> that curve around forward. The alignment arms <NUM> comprise of alignment posts <NUM> provided on the end portions <NUM> that represents the cutting trajectory of the cutting tool bit <NUM> and can be used to position the power driver adapter <NUM> visually while maintaining the alignment/trajectory of the cutting tool bit <NUM> before and during the cutting procedure. As shown in <FIG> and <FIG>, the alignment arms <NUM> and the alignment posts <NUM> are configured so that the alignment posts <NUM> are parallel with the rotation axis R of the cutting tool bit <NUM> installed on the cutting tool bit receiving base <NUM> and the two alignment posts <NUM> are also in the same plane as the rotation axis R. This configuration allows the surgeon to use the alignment posts <NUM> as visual guides to align the power driver adapter <NUM> into the joint space <NUM>. The side view in <FIG> shows the power driver adapter <NUM> in aligned position where the cutting tool bit's rotation axis R has been aligned with the intramedullary canal of the tibia <NUM> by using the alignment posts <NUM> as guides.

The flowchart 1000b in <FIG> in conjunction with <FIG> and <FIG> illustrates another embodiment of the method in which a guide assembly <NUM> is used to align the trajectory of the cutting tool bit <NUM>. The method illustrated in flowchart 1000b further comprises the step <NUM> of installing a guide assembly <NUM> in the joint space from the anterior side of the ankle after the step <NUM>. Then, after positioning the power driver adapter <NUM> equipped with a cutting tool bit <NUM> into the resected joint space <NUM> from the anterior side in step <NUM>, one engages the power driver adapter <NUM> with the guide assembly <NUM> from the anterior side to align the position of the cutting tool bit <NUM>, see step <NUM>. Next, the power driver unit <NUM> is turned on to drive the cutting tool bit <NUM> to cut into the intramedullary canal to prepare the intramedullary canal for a tibial implant, see step <NUM>.

The flowchart 2000a in <FIG> in conjunction with <FIG> illustrates an example of a posterior approach method of preparing an intramedullary canal in a tibia for receiving a tibial implant according to an embodiment. The method comprises resecting the distal end of the tibia forming a resected joint space <NUM> for receiving the tibial implant, where the joint space comprises a tibial resection surface at the distal end of the tibia and is open at the posterior side, see step <NUM>. If necessary, the proximal end of the talus may also need to be resected to properly form the resected joint space <NUM>. Then, a power driver adapter <NUM> equipped with a cutting tool bit <NUM> is positioned into the joint space <NUM> from the posterior side, where the cutting tool bit <NUM> is aimed toward the intramedullary canal of the tibia, see step <NUM>. Next, the power driver unit <NUM> is turned on to drive the cutting tool bit <NUM> to cut into the intramedullary canal to prepare the intramedullary canal for a tibial implant, see step <NUM>.

The flowchart 2000b in <FIG> illustrates another embodiment of the posterior approach method in which the method further comprises the step <NUM> of installing a guide assembly <NUM> in the joint space from the posterior side of the ankle after the step <NUM>. Then, after positioning the power driver adapter <NUM> equipped with the cutting tool bit <NUM> into the resected joint space <NUM> from the posterior side in step <NUM>, one engages the power driver adapter <NUM> with the guide assembly <NUM> from the posterior side to align the position of the cutting tool bit <NUM>, see step <NUM>. Next, the power driver unit <NUM> is turned on to drive the cutting tool bit <NUM> to cut into the intramedullary canal to prepare the intramedullary canal for a tibial implant, see step <NUM>.

<FIG> is an illustration of the posterior approach arrangement after the guide assembly <NUM> is positioned in the resected joint space <NUM>. The guide head portion <NUM> is provided with a plurality of holes <NUM> for receiving one or more fixation pins <NUM> for securing the guide assembly <NUM> to the tibia <NUM> from the posterior side. The fixation pins <NUM> are shown inserted through the holes <NUM> securing the guide assembly <NUM> to the tibia <NUM>. In this embodiment, the guide assembly <NUM> itself can include an alignment guide arm <NUM>. The alignment guide arm <NUM> can be attached to the guide head portion <NUM> via an appropriate attachment mechanism. In the illustrated example, the guide head portion <NUM> is configured with one or more pins/screws <NUM> to which the alignment guide arm <NUM> is attached. The key feature of the alignment guide arm <NUM> is that it extends out sideways from the guide head portion <NUM> and is provided with an alignment post <NUM>. This allows the operator/surgeon to visually align the guide assembly <NUM> during installation on to the tibia <NUM>, which ensures that the cutting tool bit <NUM> will be properly aligned. The power driver adapter <NUM> equipped with the cutting tool bit <NUM> is then positioned into the joint space <NUM> from the posterior side of the patient and mated with the guide assembly <NUM>. The alignment post <NUM> and the guide head portion <NUM> are configured so that when the power driver adapter <NUM> is engaged and aligned with the guide head portion <NUM> by slip-fitting the alignment pins <NUM> into the corresponding alignment slots <NUM> in the guide head portion <NUM>, the alignment post <NUM> is in parallel relation to the rotational axis R of the cutting tool bit <NUM>.

The flowchart 3000a in <FIG> in conjunction with <FIG> illustrates an example of a lateral approach method of preparing an intramedullary canal in a tibia for receiving a tibial implant according to an embodiment. The method comprises resecting the distal end of the tibia and, if necessary, the proximal end of the talus forming a resected joint space <NUM> for receiving the tibial implant, where the joint space comprises a tibial resection surface at the distal end of the tibia and is open at the lateral side, see step <NUM>. Then, the power driver adapter <NUM> equipped with the cutting tool bit <NUM> is positioned into the joint space <NUM> from the lateral side, where the cutting tool bit <NUM> is aimed toward the intramedullary canal of the tibia, see step <NUM>. Next, the power driver unit <NUM> is turned on to drive the cutting tool bit <NUM> to cut into the intramedullary canal to prepare the intramedullary canal for a tibial implant, see step <NUM>.

The flowchart 1000b in <FIG> illustrates another embodiment of the lateral approach method in which the method further comprises the step <NUM> of installing a guide assembly <NUM> in the joint space from the lateral side of the ankle after the step <NUM>. Then, after positioning the power driver adapter <NUM> equipped with the cutting tool bit <NUM> into the resected joint space <NUM> from the lateral side in step <NUM>, one engages the power driver adapter <NUM> with the guide assembly <NUM> from the lateral side to align the position of the cutting tool bit <NUM>, see step <NUM>. Next, the power driver unit <NUM> is turned on to drive the cutting tool bit <NUM> to cut into the intramedullary canal to prepare the intramedullary canal for a tibial implant, see step <NUM>.

<FIG> is an illustration of the lateral approach arrangement where the guide assembly <NUM> is then positioned in the resected joint space <NUM>. The guide head portion <NUM> is provided with a plurality of holes <NUM> for receiving one or more fixation pins <NUM> for securing the guide assembly <NUM> to the tibia <NUM> from the posterior side. The fixation pins <NUM> are shown inserted through the holes <NUM> securing the guide assembly <NUM> to the tibia <NUM>. The power driver adapter <NUM> equipped with the cutting tool bit <NUM> is then positioned into the joint space <NUM> from the lateral side of the patient and mated with the guide assembly <NUM>. Similar to the description provided above in connection with <FIG>, in some embodiments of the lateral approach arrangement, the guide assembly <NUM> can include an alignment guide arm <NUM> that is provided with an alignment post <NUM>. The function of the alignment guide arm <NUM> and the alignment post <NUM> in this embodiment is similar to the embodiment shown in <FIG> and described.

The flowchart 4000a in <FIG> in conjunction with <FIG> illustrates an example of an anterior approach method of preparing the proximal end of a talus for receiving a talar implant according to an embodiment. The method comprises resecting the distal end of the tibia and, if necessary, the proximal end of the talus forming a resected joint space <NUM>, where the joint space comprises a tibial resection surface at the distal end of the tibia and a talar resection surface at the proximal end of the talus and the joint space <NUM> is open at the anterior side, see step <NUM>. Then, the power driver adapter <NUM> equipped with the cutting tool bit <NUM> is positioned into the joint space <NUM> from the anterior side, where the cutting tool bit <NUM> is aimed toward the talus, see step <NUM>. Next, the power driver unit <NUM> is turned on driving the cutting tool bit <NUM> to cut into the talar resection surface and form a void extending into the talus for receiving a tarlar stem and/or augment for a talar implant, see step <NUM>.

The flowchart 4000b in <FIG> illustrates an example of a posterior approach method of preparing the proximal end of a talus for receiving a talar implant according to an embodiment. The method comprises resecting the distal end of the tibia and, if necessary, the proximal end of the talus forming a resected joint space <NUM>, where the joint space comprises a tibial resection surface at the distal end of the tibia and a talar resection surface at the proximal end of the talus and the joint space <NUM> is open at the posterior side, see step 4010b. Then, the power driver adapter <NUM> equipped with the cutting tool bit <NUM> is positioned into the joint space <NUM> from the posterior side, where the cutting tool bit <NUM> is aimed toward the talus, see step 4020b. Next, the power driver unit <NUM> is turned on driving the cutting tool bit <NUM> to cut into the talar resection surface and form a void extending into the talus for receiving a talar stem and/or augment for a talar implant, see step 4030b.

The flowchart 4000c in <FIG> illustrates an example of a lateral approach method of preparing the proximal end of a talus for receiving a talar implant according to an embodiment. The method comprises resecting the distal end of the tibia and, if necessary, the proximal end of the talus forming a resected joint space <NUM>, where the joint space comprises a tibial resection surface at the distal end of the tibia and a talar resection surface at the proximal end of the talus and the joint space <NUM> is open at the lateral side, see step 4010c. Then, the power driver adapter <NUM> equipped with the cutting tool bit <NUM> is positioned into the joint space <NUM> from the lateral side, where the cutting tool bit <NUM> is aimed toward the talus, see step 4020c. Next, the power driver unit <NUM> is turned on driving the cutting tool bit <NUM> to cut into the talar resection surface and form a void extending into the talus for receiving a talar stem and/or augment for a talar implant, see step 4030c.

In the various embodiments of the methods described herein, the power driver adapter <NUM> equipped with the cutting tool bit <NUM> can be positioned into that ankle joint space between the tibia and the talus before any resection cuts of the tibia or the talus are made. In such examples, an appropriately configured guide assembly jig (not shown) can be inserted into the joint between the tibia and the talus, then guide and position the cutting tool bit end of the power driver adapter <NUM> between the tibia and the talus before the resection cuts are made to the distal end of the tibia or the proximal end of the talus.

Claim 1:
A power driver adapter (<NUM>) configured for cutting into an intramedullary canal of a tibia (<NUM>), the power driver adapter comprising:
an elongated body (<NUM>) having a driving end (<NUM>), a cutting tool bit receiving end (<NUM>), and a longitudinal axis (L);
wherein the driving end (<NUM>) has a drive shaft (<NUM>) coaxially located with the longitudinal axis (L) and configured to mate with a power delivering unit (<NUM>) that rotates the drive shaft coaxially about the longitudinal axis;
wherein the cutting tool bit receiving end (<NUM>) comprises a cutting tool bit receiving base (<NUM>) that is configured for engaging with a cutting tool bit (<NUM>) and rotates the cutting tool bit for cutting action, wherein the cutting tool receiving base (<NUM>) rotates with a rotational axis (R) that is orthogonal to the longitudinal axis (L) of the elongated body (<NUM>) such that the cutting tool bit receiving end (<NUM>) is configured to translate linearly in a direction that is coaxial to the rotational axis (R) and orthogonal to the longitudinal axis (L) when the cutting tool bit is being rotated;
wherein the elongated body (<NUM>) comprises a series of gears connecting the drive shaft (<NUM>) to the cutting tool bit receiving end (<NUM>);
wherein the series of gears are configured in an arrangement that converts the coaxial rotation of the drive shaft (<NUM>) to the rotation of the cutting tool bit receiving base (<NUM>).