Patent Description:
It is important to take precautions when cutting around sensitive anatomy. While existing cutting devices, such as bone drills, are suitable for their intended use, they are subject to improvement. The present disclosure advantageously includes a cutting device with a safety mechanism for use in anatomical and non-anatomical applications. One skilled in the art will appreciate that the present disclosure includes numerous additional advantages and unexpected results as well.

<CIT> discloses a drill-type cranial perforator of the type which comprises a front drill head assembly made up of a leading inner drill and a trailing outer drill, and a rear support and drive assembly adapted to enable both drills so long as the leading inner drill is encountering a resistive surface and to disable both drills when the leading inner drill stops encountering the resistive surface. The leading inner drill has at least one drilling flute with a forward cutting edge including a reentrant cutting segment axially rearward from the outer end of the forward cutting edge and extending inwardly towards the longitudinal axis of the perforator.

The invention provides a drill assembly according to claim <NUM> and a method for cutting a non anatomical object according to claim <NUM>. Methods for cutting anatomical objects are also described herein, but they do not form part of the invention as claimed.

The drawings described herein are for illustrative purposes only of select embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

With initial reference to <FIG> and <FIG>, an exemplary drill assembly attachment in accordance with the present disclosure is illustrated at reference numeral <NUM>. The attachment <NUM> is configured for use to cut any suitable anatomical or non-anatomical objects. As illustrated in the example of <FIG>, the attachment <NUM> may be used to cut bone of a patient <NUM>, such as the patient's cranium. The attachment <NUM> is connected to any suitable motor <NUM>, and is directed to the patient <NUM> by a user <NUM>, such as a surgeon, or any automated surgical navigation device. In non-anatomical applications, the user <NUM> may be any person or automated device capable of using the attachment <NUM> to cut an object.

With particular reference to <FIG>, the attachment <NUM> generally includes a base <NUM>, which is configured to be connected to the motor <NUM>. A locking collar <NUM> is adjacent to the base <NUM>. Rotation of the locking collar <NUM> rotationally locks a cutting tool <NUM> to the attachment <NUM>. The motor <NUM> may be any suitable pneumatic motor, electric motor, etc..

Proximate to the locking collar <NUM> is a grip collar <NUM>, which provides a roughened surface to facilitate grip of the attachment <NUM> by the user <NUM>. Extending from the grip collar <NUM> is a tube <NUM> into which the cutting tool <NUM> is inserted. The cutting tool <NUM> will typically include a cutting head <NUM>. The cutting tool <NUM> may be any suitable cutting tool. Suitable cutting tools include any suitable drill bits, burs, and saw, for example. The cutting tool <NUM> may be configured for any suitable plunge cut or lateral cut. With respect to plunge cuts and as described in detail herein, the cutting tool <NUM> is slidably or axially movable along a longitudinal axis A of the attachment <NUM>. In some applications, the cutting tool <NUM> is also rotatable about the longitudinal axis A.

With additional reference to <FIG> and <FIG>, additional details of the attachment <NUM> will now be described. The attachment <NUM> further includes a tool shaft <NUM> defined by the tube <NUM>. The tool <NUM> extends through the tool shaft <NUM>, through the grip collar <NUM>, and into the locking collar <NUM>. The tool shaft <NUM> is supported within the tube <NUM> by one or more bearings <NUM>. The bearings <NUM> closest to the grip collar <NUM> are preloaded by a spring <NUM> to ensure that the bearings <NUM> do not overheat during use. Within the locking collar <NUM> is a locking assembly <NUM>. The locking assembly <NUM> is any suitable locking mechanism configured to lock the tool <NUM> to the attachment <NUM>, and allow the tool <NUM> to be unlocked and replaced with another tool.

The attachment <NUM> further includes a pressure loaded drive control assembly <NUM>. The pressure loaded drive control assembly <NUM> generally includes a driven member <NUM> and a drive member <NUM>. The driven member <NUM> is slidably mounted within the attachment <NUM>, and axially slides in unison with the tool <NUM> along the longitudinal axis A. The drive member <NUM> is configured to be driven by the motor <NUM>. The drive member <NUM> includes a drive shaft <NUM> accessible at a receptacle <NUM> defined by the base <NUM>. A connector of the motor <NUM> is plugged into the receptacle <NUM> and placed into cooperation with a connector <NUM> of the drive shaft <NUM>. Energy or force, generated by the motor <NUM> is transferred to the drive member <NUM> by way of the drive shaft <NUM> thereof. For example, rotational energy from the motor <NUM> is transferred to the driveshaft <NUM> for rotating the drive member <NUM>.

<FIG> illustrates the pressure loaded drive control assembly <NUM> with additional detail. The pressure loaded drive control assembly <NUM> further includes a driven gear head <NUM> of the driven member <NUM>, which has driven gear teeth <NUM>. The drive member <NUM> further includes a drive gear head <NUM> having drive gear teeth <NUM>. In the active configuration of <FIG>, the driven gear teeth <NUM> mesh with the drive gear teeth <NUM>. Thus, in the exemplary active configuration of <FIG>, the drive member <NUM> rotates the driven member <NUM>, which rotates the tool <NUM>.

The pressure loaded drive control assembly <NUM> further includes a bearing <NUM> seated on a bearing case <NUM>. The bearing case <NUM> is axially slidable along the longitudinal axis A. The bearing case <NUM> includes a bearing flange <NUM>. A biasing member <NUM>, such as a spring, is in direct or indirect cooperation with the bearing case <NUM>, such as at the bearing flange <NUM>. The biasing member <NUM> biases the bearing case <NUM> in an inactive configuration, which is described below in conjunction with the description of <FIG>. The driven member <NUM> is connected to the bearing case <NUM>, and axially moves along the longitudinal axis A with the bearing case <NUM>. As a result, the driven member <NUM> is biased in the inactive configuration of <FIG> by the biasing member <NUM>. The driven member <NUM> also slides in unison with the tool <NUM> along the longitudinal axis A. The driven member <NUM> is connected directly to, or indirectly to, the tool <NUM>.

<FIG> and <FIG> illustrate the attachment <NUM> in use with the head <NUM> of the tool <NUM> moved in a first direction A as a result of the head <NUM> being pressed or loaded against the object <NUM> to be cut. Depressing the attachment <NUM> against the object <NUM> applies pressure to the tool <NUM> to axially move the tool <NUM> along the longitudinal axis A further into the tube <NUM> in the first direction A. Because the driven member <NUM> moves with the tool <NUM>, the driven member <NUM> also axially moves along the longitudinal axis A in the first direction A. The driven member <NUM> moves into cooperation with the drive member <NUM> such that the driven gear teeth <NUM> mesh with the drive gear teeth <NUM> for transferring energy or a force from the motor <NUM> to the tool <NUM> to drive the tool <NUM> for cutting the object <NUM>, such as a rotational force.

<FIG> illustrate the attachment <NUM> in the inactive configuration. The biasing member <NUM> moves the attachment <NUM> to the inactive configuration after the head <NUM> disengages or penetrates the object <NUM>. In the inactive configuration, the tool <NUM> is no longer driven by the motor and no longer rotates, thus decreasing any possibility that objects and/or tissue beyond the object <NUM> will be cut by the head <NUM>. Specifically, once the head <NUM> passes through the object <NUM>, sufficient opposing axial pressure or force is no longer applied to the head <NUM>. As soon as pressure or opposing axial force is not applied to the head <NUM>, the biasing member <NUM> pushes the driven member <NUM> away from the drive member <NUM>, which in turn axially moves the tool <NUM> along the longitudinal axis A in a second direction B such that the tool <NUM> extends further out from within the tube <NUM>. In this inactive configuration, the driven gear teeth <NUM> are no longer in cooperation with the drive gear teeth <NUM>, and thus energy or driven force is no longer transferred from the drive member <NUM> to the driven member <NUM>. This idles the cutting tool <NUM> so that it is no longer rotated or driven by the motor, which advantageously provides an additional safety feature to further protect protects an area beyond the object <NUM> from being cut by the tool <NUM>.

With reference to <FIG>, another pressure (i.e., force) loaded drive control assembly in accordance with the present disclosure is illustrated at reference numeral 50A. The drive control assembly 50A includes numerous features that are substantially similar to the drive control assembly <NUM>, which are illustrated using the same reference numerals but also including the letter "A. " The pressure loaded drive control assembly 50A is similar to the assembly <NUM>, but the driven member 52A and the drive member 54A are both at a distal end of the tube <NUM>. The driven member 52A is connected directly to the tool 30A, or is monolithic with the tool 30A. The biasing member 96A biases the driven member 52A in the inactive configuration such that the driven gear teeth 72A of the driven member 52A are spaced apart from (and decoupled from) the drive gear teeth 82A of the drive member 54A.

With reference to <FIG>, when the tool 30A is pressed against the object <NUM> to be cut, the driven member 52A is axially moved along the longitudinal axis A in direction A until the driven gear teeth 72A cooperate with the drive gear teeth 82A to rotate the tool 30A. With reference to <FIG>, after the head 32A cuts through the object <NUM>, the head 32A is no longer under opposed axial loads or forces, which allows the biasing member 96A to decouple the driven and drive members 52A, 52B, and move the driven member 52A outward along the longitudinal axis A in direction B back to the inactive position. As a result, the driven gear teeth 72A are no longer in cooperation with the drive gear teeth 82A, the drive member 54A no longer drives the driven member 52A, and the tool <NUM> is not rotated.

Although the driven members <NUM>/52A and the drive members <NUM>/54A are described above as including gear teeth, any other suitable coupling and decoupling configuration may be used to selectively transfer energy from the drive members <NUM>/54A to the driven members <NUM>/52A. For example and as illustrated in <FIG>, the present disclosure further provides for a pressure loaded drive control assembly 50B. The assembly 50B is generally a friction clutch configuration. Specifically, the assembly 50B includes a driven member 52B having a driven surface <NUM>, and a drive member 54B having a drive surface <NUM>. In the inactive configuration of <FIG>, the driven member 52B and the drive member 54B are spaced apart so that the tool 30B and the head 32B thereof are not rotated. The biasing member 96B biases the driven member 52B and the drive member 54B in this inactive, spaced apart configuration.

When the cutting tool 30B is depressed against the object <NUM> to be cut, the driven member 52B is moved along the longitudinal axis until the driven surface <NUM> is received within the drive surface <NUM>. The driven surface <NUM> and the drive surface <NUM> each include any suitable surface treatments and/or inserts to provide a friction lock between the driven surface <NUM> and the drive surface <NUM>. Thus, with the driven surface <NUM> seated within the drive surface <NUM>, rotation of the drive member 54B by the motor <NUM> rotates driven member 52B and the cutting tool 30B. After the tool 30B cuts through the object <NUM>, pressure is no longer applied against the cutting tool <NUM>, which allows the biasing member <NUM> to move the driven member 52B back to the inactive configuration illustrated in <FIG> so that the cutting tool <NUM> is no longer driven.

With reference to <FIG>, the pressure loaded drive control assembly <NUM>, 50B may be self-contained within a housing <NUM>. The housing <NUM> including the pressure loaded drive control assembly <NUM> or 50B may be removably coupled to any suitable existing drill assembly attachment <NUM>' to "retrofit" the attachment <NUM> with a safety feature for reducing any possibility of unintentionally cutting sensitive tissue, organs, or non-anatomical material/device located beyond the object <NUM>.

The pressure loaded drive control assemblies <NUM>, 50A, 50B may be used with any suitable tool <NUM> in addition to a bur or drill tip. For example and as illustrated in <FIG>, the tool <NUM> may include a saw tip <NUM>. Any of the pressure loaded drive control assemblies <NUM>, 50A, 50B may be used to control energy transfer to the saw tip <NUM> as described above and as one skilled in the art will appreciate.

The present disclosure thus advantageously provides for the drill assembly attachment <NUM> and the pressure loaded drive control assemblies <NUM>, 50A, and 50B described above, which advantageously reduce any risk of cutting through the object <NUM> and damaging an anatomical organ, tissue, etc., or a non-anatomical object. With respect to anatomical applications, the present disclosure applies to use of the drill assembly attachment <NUM> to carry out any suitable procedure, such as the following examples: mastoidectomy, craniotomy, bur hole formation, pilot hole formation for spinal fusion, laminectomy/ laminectomies, bone resection, tissue resection, and robotic surgical procedures. The present disclosure provides an additional layer of safety and control when cutting around sensitive anatomy. With respect to robotic applications in particular, the present disclosure provides a primary layer of safety and control when cutting around sensitive areas instead of relying entirely on software control.

Claim 1:
A drill assembly (<NUM>) comprising:
a cutting tool (30B) slidably movable along a longitudinal axis (A) of the drill assembly (<NUM>) and drivable to cut an object (<NUM>);
a pressure loaded drive control assembly (50B) configurable in an active configuration and an inactive configuration, in the active configuration the pressure loaded drive control assembly (50B) transfers energy from a motor (<NUM>) to the cutting tool (30B) to drive the cutting tool (30B), in the inactive configuration the pressure loaded drive control assembly (50B) prevents energy transfer from the motor (<NUM>) to the cutting tool (30B); and
a biasing member (96B) of the pressure loaded drive control assembly (<NUM>) configured to bias the pressure loaded drive control assembly (<NUM>) in the inactive configuration;
wherein depressing the cutting tool (30B) against the object (<NUM>) applies a load to the cutting tool (30B) to move the cutting tool (30B) along the longitudinal axis (A) in a first direction and moves the pressure loaded drive control assembly (50B) from the inactive configuration to the active configuration;
wherein the biasing member (96B) moves the cutting tool (30B) along the longitudinal axis (A) in a second direction that is opposite to the first direction and returns the pressure loaded drive control assembly (50B) to the inactive configuration from the active configuration when the load is no longer applied to the cutting tool (30B); and
characterised in that the pressure loaded drive control assembly (50B) is a friction clutch configuration.