Patent Description:
Conventional medical and surgical procedures routinely involve the use of surgical tools and instruments which allow surgeons to approach and manipulate surgical sites. By way of non-limiting example, rotary instruments such as handheld drills are commonly utilized in connection with orthopedic procedures to address various musculoskeletal conditions, such as trauma, sports injuries, degenerative diseases, joint reconstruction, and the like. In procedures where handheld drills or similar surgical instruments are employed, rotational torque selectively generated by an actuator (e.g., an electric motor) is used to rotate a releasably-attachable drill bit or other surgical attachments at different speeds.

A surgical handpiece assembly drills bores in the tissue against which the drill bit is applied. One type of surgical procedure in which it is necessary to drill a bore is a trauma procedure to repair a broken bone. In this type of procedure, an elongated rod, sometimes called a nail, is used to hold the fractured sections of the bone together. To hold the nail in place, one or more bores are driven into the bone. These bores are positioned to align with complementary holes formed in the nail. A screw is inserted in each aligned bore and nail hole. The screws hold the nail in the proper position relative to the bone.

In another type of procedure, an implant known as a plate is secured to the outer surfaces of the fractured sections of a bone to hold the sections together. Screws hold the plate to the separate sections of bone. To fit a screw that holds a plate to bone it is necessary to first drill a bore to receive the screw.

As part of a procedure used to drill a screw-receiving bore in a bone, it is desirable to know the end-to-end depth of the bore. This information allows the surgeon to select size of screw that is fitted in the bore hole. If the screw is too short, the screw may not securely hold the nail into which the screw is inserted in place. If the screw is too long, the screw can extend an excessive distance out beyond the bone. If the screw extends an excessive distance beyond the bone, the exposed end of the screw can rub against the surrounding tissue. If this event occurs, the tissue against which the screw rubs is affected.

Accordingly, an integral part of many bone bore-forming procedures is the measuring of the depth of the bore. Currently, this measurement is often taken with a depth gauge separate from the drill. This requires the surgeon to, after withdrawing the drill bit from the bore, insert the depth gauge into the bore. Then, based on tactile feedback, the surgeon sets the gauge so the distal end of the gauge only extends to the far opening of the bore. Once these processes are complete, the surgeon reads the gauge to determine the depth of the bore.

It is desirable to identify apparatus that improve these devices.

Document <CIT> discloses a device for drilling holes in bone and configured to determine bone screw length. The device includes a surgical power drill comprising: a) a housing and; b) a measuring device releasably attached or fixed to the housing. The measuring device is configured to measure the distance covered by the housing in the direction of the longitudinal axis and relative to a surface of an implant or a bone during a drilling process. The measuring device comprises a processing unit to record the distance covered with respect to time. The processing unit comprises one or more differentiators to determine at least the first and second derivatives of the distance covered with respect to time. The processing unit further comprises a peak detector to analyze one or more peaks occurring in the graph of the highest derivative with respect to time. The measuring device further comprises a laser device or an ultrasound position sensor for displacement assessment.

Document <CIT> discloses methods and apparatus for integrating an electromagnetic navigation system and a tool, and for aligning the tool with a target. An apparatus includes a sensor tool, a tool, a field generator, a display, and a computer. The sensor tool attaches to a target component in a unique position relative to target features. The field generator is fixed relative to the tool except in rotation about a tool axis. The display is adjustably mounted to the tool and automatically adjusts image parameters. Target registration and error compensation methods are disclosed. The system detects magnetic field and signal disturbances that may lead to inaccurate navigation, filters navigation data, and adjusts filtering parameters based on detected conditions.

The present disclosure relates generally to a system for calibrating a surgical handpiece system capable of determining drill depth to an orthopedic implant set. An exemplary configuration provides a system including a surgical handpiece system. The surgical handpiece system includes a first housing and a depth measurement extension movably coupled to the first housing. A displacement sensor assembly is coupled to the first housing and configured to generate a signal responsive to displacement of the depth measurement extension. A calibration fixture is configured to engage the depth measurement extension of the surgical handpiece system to determine an adjustment of the orthopedic implant set. The calibration fixture has a second housing that defines a lumen that is configured to receive a surgical screw of the orthopedic implant set. The second housing has a proximal end configured to engage a distal surface of the first housing of the surgical handpiece system to axially constrain the second housing relative to the first housing. A slider is movably coupled to the second housing of the calibration fixture. The slider is configured to move axially relative to the second housing. The slider has a proximal surface configured to engage with the depth measurement extension of the surgical handpiece system. The slider also has a distal surface configured to engage with the surgical screw. The adjustment of the orthopedic implant set is determined based on the signal from the displacement sensor assembly and a nominal size of the surgical screw.

Another exemplary configuration provides a system for calibrating a surgical handpiece system capable of determining drill depth to an orthopedic implant set. The system includes a surgical handpiece system. The surgical handpiece system includes a housing and a depth measurement extension movably coupled to the housing. A displacement sensor assembly is coupled to a distal portion of the housing. The displacement sensor assembly is configured to generate a displacement signal responsive to movement of the depth measurement extension relative to the housing. A processor is configured to receive the signal from the displacement sensor assembly. A calibration fixture is configured to engage the distal portion of the housing of the surgical handpiece system to engage the depth measurement extension of the surgical handpiece system. One of the surgical handpiece system and the calibration fixture includes a presence sensor and the other of the surgical handpiece system and the calibration fixture includes an emitter. The presence sensor is configured to generate a signal responsive to presence of the emitter when the calibration fixture engages the distal portion of the housing of the surgical handpiece system. The processor is configured to receive the signal from the presence sensor and determine the calibration fixture is engaging the distal portion of the housing of the surgical handpiece system to operate the surgical handpiece system in a calibration mode. An adjustment of the orthopedic implant set is determined based on the signal from the displacement sensor assembly while the surgical handpiece system is in the calibration mode and on a nominal size of the surgical screw.

Yet another exemplary configuration provides a method of calibrating a surgical handpiece system capable of determining drill depth to an orthopedic implant set, with the method not forming part of the claimed invention. The method including providing a surgical handpiece system including a first housing and a depth measurement extension movable relative to the first housing. The method also including providing a calibration fixture that includes a second housing defining a lumen and a slider movable relative to the second housing at least partially within the lumen. The method also including selecting a surgical screw having a certain nominal size from the orthopedic implant set. The method further including selecting a surgical plate to be used in an upcoming surgery from the orthopedic implant set. The method also including engaging the depth measurement extension of the surgical handpiece system with the slider of the calibration fixture. The method further including inserting the surgical screw through the surgical plate to engage a head of the surgical screw to abut the surgical plate. The method also including engaging the slider of the calibration fixture with the surgical screw. The method further including engaging a distal surface of the second housing with the surgical plate. The method also including depressing the depth measurement extension of the surgical handpiece system with the slider of the calibration fixture. The method further including determining an adjustment of the orthopedic implant set based on the nominal size of the surgical screw and a displacement of the depressed depth measurement extension to calibrate the surgical handpiece system.

Another exemplary configuration provides a method for calibrating a surgical handpiece system capable of determining drill depth to an orthopedic implant set, with the method not forming part of the claimed invention. The method including providing a calibration fixture and a surgical handpiece system that includes a displacement sensor assembly. One of the calibration fixture and the surgical handpiece system includes a presence sensor. The other of the calibration fixture and the surgical handpiece system includes an emitter. The method also including engaging a distal portion of the surgical handpiece system with a proximal end of the calibration fixture. The method further including determining the calibration fixture is engaging the distal portion of the surgical handpiece system with the presence sensor. The surgical handpiece system entering a calibration mode responsive to the presence sensor detecting the emitter. The method also including determining displacement of a depth measurement extension of the surgical handpiece system while in calibration mode. The method further including determining an adjustment of the orthopedic implant set based on displacement of the depressed depth measurement extension during calibration mode.

Yet another exemplary configuration provides a system for calibrating a surgical handpiece system capable of determining drill depth to an orthopedic implant set. The system includes the surgical handpiece system. The surgical handpiece system includes a depth measurement extension configured to determine a thickness of bone when a drill bit is attached and used to drill through the bone. A calibration block is configured to engage with a depth gauge supplied with the orthopedic implant set to determine an adjustment of the orthopedic implant set. The calibration block includes a top surface having a curved profile designed to interface with a plate from the orthopedic implant set. The top surface defines one or more holes to receive the depth gauge. A bottom surface of the block includes a depression intended to temporarily hold a distal portion of the depth gauge.

The invention is defined in the claims and provides a surgical handpiece system to determine a suitable screw length for bone fixation with a bone plate that compensates an initial screw length value based on orientation of the surgical handpiece system during a drilling process. The surgical handpiece system includes a surgical handpiece assembly. The surgical handpiece assembly has a handpiece housing and a motor disposed within the handpiece housing and configured to generate torque. A depth measurement extension is movably coupled to the handpiece housing. A sensor is configured to generate an orientation signal responsive to orientation of the depth measurement extension. A drill bit is configured to be coupled to and receive torque from the motor of the surgical handpiece assembly. A processor is configured to receive the signals from the sensor and determine the suitable screw length for bone fixation based on signals from the sensor.

With reference to the drawings, where like numerals are used to designate like structure throughout the several views, a surgical handpiece system is shown at <NUM> in <FIG> for performing an operational function associated with medical and/or surgical procedures. In the representative configuration illustrated herein, the surgical handpiece system <NUM> is employed to facilitate penetrating tissue of a patient, such as bone. To this end, the illustrated configuration of the surgical handpiece system <NUM> comprises a surgical handpiece assembly <NUM> and an end effector assembly, generally indicated at <NUM>. The end effector assembly <NUM>, in turn, comprises a drill bit <NUM> and a tip protector <NUM>. As is best depicted in <FIG>, the drill bit <NUM> extends generally longitudinally along an axis AX between a cutting tip portion, generally indicated at <NUM>, and an insertion portion, generally indicated at <NUM>. As is described in greater detail below, the cutting tip portion <NUM> is configured to engage tissue, and the insertion portion <NUM> is configured to facilitate releasable attachment of the drill bit <NUM> to the surgical handpiece assembly <NUM>.

In order to help facilitate attachment of the drill bit <NUM> to the surgical handpiece assembly <NUM>, in some configurations, the tip protector <NUM> is configured to releasably secure to the cutting tip portion <NUM> of the drill bit <NUM> while concealing at least a portion of the cutting tip portion <NUM> of the drill bit <NUM>, thereby allowing a user (e.g., a surgeon) of the surgical handpiece system <NUM> to handle and position the drill bit <NUM> safely during attachment to the surgical handpiece assembly <NUM>. Once the end effector assembly <NUM> has been attached to the surgical handpiece assembly <NUM>, the tip protector <NUM> is subsequently removed from the cutting tip portion <NUM> of the drill bit <NUM>, and the surgical handpiece system <NUM> can then be utilized to penetrate tissue.

A variety of different orthopedic implant sets, which can include screws, plates, nails, or pins along with a depth gauge, may be used from various manufacturers, each implant set may include a variety of different screws with a nominal identification of screw length. The depth gauge accompanying an orthopedic implant set is configured to measure the bore depth and provide a user with a measurement that corresponds to the nominal screw length in that orthopedic implant set. The depth gauge accounts for items like the thickness of the plate and how the manufacturer determines screw length, e.g. with or without the thickness of the screw head. The difference between the thickness of the bone and the nominal screw length is referred to as an adjustment.

Referring now to <FIG>, in the representative configuration illustrated herein, the surgical handpiece assembly <NUM> is realized as a handheld drill with a pistol-grip shaped handpiece housing assembly <NUM> which releasably attaches to a battery <NUM> (battery attachment not shown in detail). However, it is contemplated that the handpiece housing assembly can have any suitable shape with or without a pistol grip. While the illustrated surgical handpiece assembly <NUM> employs a battery <NUM> which is releasably attachable to the handpiece housing assembly <NUM> to provide power to the surgical handpiece assembly <NUM> utilized to rotate the drill bit <NUM>, it will be appreciated that the surgical handpiece assembly <NUM> may be configured in other ways, such as with an internal (e.g., non-removable) battery, or with a tethered connection to an external console, power supply, and the like. Other configurations are contemplated.

In the illustrated configuration, the battery <NUM> or other power source provides power to a controller <NUM> which, in turn, is disposed in communication with a user input device <NUM> and an actuator assembly <NUM>. The user input device <NUM> and the actuator assembly <NUM> are each supported by the handpiece housing assembly <NUM>. The controller <NUM> is generally configured to facilitate operation of the actuator assembly <NUM> in response to actuation of the user input device <NUM>. The user input device <NUM> is shown as a trigger-style configuration in the illustrated configuration, is responsive to actuation by a user (e.g., a surgeon), and communicates with the controller <NUM>, such as via electrical signals produced by magneto-resistive sensors (e.g., Hall effect sensors) and magnets. Thus, when the surgeon actuates the user input device <NUM> to operate the surgical handpiece assembly <NUM>, the controller <NUM> directs power from the battery <NUM> to the actuator assembly <NUM> which, in turn, generates rotational torque employed to rotate the drill bit <NUM> or other surgical end effector, as described in greater detail below. Those having ordinary skill in the art will appreciate that the handpiece housing assembly <NUM>, the battery <NUM>, the controller <NUM>, and the user input device <NUM> could each be configured in a number of different ways to facilitate generating rotational torque without departing from the scope of the present disclosure.

Referring now to <FIG>, the illustrated configuration of the surgical handpiece system <NUM> further comprises a measurement module, generally indicated at <NUM>, which may be optionally configured to releasably attach to the surgical handpiece assembly <NUM> to provide the surgeon with measurement functionality during use. To this end, and as is shown in <FIG> and <FIG>, the measurement module <NUM> generally comprises a module housing <NUM>, a guide bushing <NUM>, a depth measurement extension <NUM>, a displacement sensor assembly <NUM>, and a rotatable gear <NUM>. In some configurations, the module housing <NUM> is releasably attachable to the handpiece housing assembly <NUM>. In other configurations, the measurement module <NUM> is releasably attached to the surgical handpiece assembly <NUM> in another manner. In certain configurations, the measurement module <NUM> may include one or more buttons for controlling a function of the measurement module <NUM>. The module housing <NUM> generally supports the various components of the measurement module <NUM>. In still other configurations, the surgical handpiece assembly <NUM> and the measurement module <NUM> are not releasably attached to each other. Instead, the surgical handpiece assembly <NUM> and the measurement module <NUM> form one integral assembly such that the module housing <NUM> forms a portion of the handpiece housing assembly <NUM>.

The depth measurement extension <NUM> is disposed within the guide bushing <NUM> and is supported for translational movement along a measurement axis MX. When the measurement module <NUM> is attached to the surgical handpiece assembly <NUM>, the measurement axis MX is arranged to be coaxial with the axis AX. An elongated recessed slot <NUM> (partially depicted in <FIG>) is optionally formed transversely into the depth measurement extension <NUM> and extends longitudinally.

The depth measurement extension <NUM> further comprises a plurality of rack teeth <NUM> disposed linearly along at least a partial length of the depth measurement extension <NUM> which are disposed in meshed engagement with the gear <NUM> arranged adjacent a distal end of the guide bushing <NUM>. As shown in <FIG>, the window <NUM> of the guide bushing <NUM> is arranged adjacent to the gear <NUM> to facilitate the meshed engagement between the rack teeth <NUM> and the gear <NUM> such that rotation of the gear <NUM> and movement of the depth measurement extension <NUM> are directly proportional. The displacement sensor assembly <NUM> is responsive to rotation of the gear <NUM> resulting from axial movement of the depth measurement extension <NUM>, and may be realized with a potentiometer <NUM> (shown in <FIG>), a rotary encoder, and the like, in order to generate electrical signals representing changes in the position of the depth measurement extension <NUM> along the measurement axis MX. Thus, it will be appreciated that the displacement sensor assembly <NUM> is able to provide the surgical handpiece system <NUM> with enhanced functionality. By way of example, in some configurations, the displacement sensor assembly <NUM> may be disposed in communication with the controller <NUM>, which may be configured to interrupt or adjust how the motor <NUM> is driven based on movement of the depth measurement extension <NUM>, such as to slow rotation of the drill bit <NUM> at a specific drilling depth into tissue. In some configurations, the controller <NUM> may be disposed in the measurement module <NUM>. In still other configurations, the displacement sensor assembly <NUM> may be disposed in communication with a sub-controller (not shown) of the measurement module <NUM> and the sub-controller may be disposed in communication with the controller <NUM>. The displacement sensor assembly <NUM> may also be disposed in communication with a display <NUM>, such as a display screen, one or more light-emitting diodes (LEDs), and the like, to provide the surgeon with information relating to movement of the depth measurement extension <NUM>, such as to display a real-time drilling depth, a recorded historical maximum drilling depth, and the like. Other configurations are contemplated. This same information may also be communicated to the user with a speaker to provide audio indications of the real-time drilling depth, a recorded historical maximum drilling depth, and the like. The disclosure of <CIT> entitled "Powered Surgical Drill With Integral Depth Gauge That Includes A Probe That Slides Over A Drill Bit" and filed on September <NUM>, <NUM>.

Various components of the measurement module <NUM> could be arranged in a number of different ways. Moreover, while the illustrated measurement module <NUM> attaches to the illustrated surgical handpiece assembly <NUM> and is compatible with the calibration fixtures <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> of the present disclosure, it is contemplated that the surgical handpiece system <NUM> could omit the measurement module <NUM> in some configurations, such as to employ different types of modules, housings, covers, and the like. The measurement module <NUM> may also be affixed to the surgical handpiece assembly <NUM> in a different location and may be detachable or may be a permanent part of the surgical handpiece assembly <NUM>. In configurations where the measurement module <NUM> is not attached to the distal end of the surgical handpiece assembly <NUM>, components described or depicted herein as abutting the measurement module <NUM> may instead abut the surgical handpiece assembly <NUM>. Further, while the depth measurement extension <NUM> is illustrated as a cannula it could instead partially enclose the drill bit <NUM>, or the depth measurement extension <NUM> could be parallel to and offset from the drill bit <NUM>. In other words, any device that includes a depth measurement extension <NUM> may be compatible with the devices and methods described herein.

<FIG> depicts the basic electrical components of surgical handpiece system <NUM> that, based on position of the depth measurement extension <NUM>, provide an indication of the depth of the bore formed by the drill bit <NUM>. Not identified are the voltage regulating components that ensure the drive signals of the appropriate potentials are supplied to the bore depth displaying components. The components that provide the information about bore depth include the potentiometer <NUM>. A voltage is applied to one end of the potentiometer <NUM>. The opposed end of the potentiometer <NUM> is tied to ground. The voltage present at the wiper of the potentiometer <NUM> is applied to a processor <NUM>. Also shown attached to the processor <NUM> is a zeroing switch <NUM>. In the zeroing switch <NUM> may be mounted to the display <NUM>.

Each set of plate(s) <NUM> and screws <NUM> may provide a nominal screw length to identify the various screw sizes within the set. The nominal screw length provided for any particular set of plate(s) <NUM> and screws <NUM> does not necessarily correspond to any consistent metric. The nominal screw length could be the actual screw length with or without the screw head. The nominal screw length may or may not take into account the thickness of the plate <NUM> that the screw will ultimately be used with. To ensure that the surgeon correctly selects a screw <NUM> that is appropriate for the particular surgical procedure, a manufacturer-specific depth gauge <NUM> (See, e.g. <FIG>) is provided with each set of plates <NUM> and screws <NUM>.

The depth gauge <NUM> is used to measure thickness of a bone <NUM>, as shown in <FIG>, and the measurement markings <NUM> on the depth gauge <NUM> associated with a given set correspond to the nominal screw length of the screws <NUM> provided with the set.

In order for the surgical handpiece system <NUM> to provide sufficient information to enable selection of the screw <NUM>, the surgical handpiece system <NUM> must be calibrated to work with any one of over <NUM>,<NUM> different plate <NUM> and screw <NUM> sets. As will be described below, the surgical handpiece system <NUM> may be calibrated using a plate <NUM> and screw <NUM> provided with a particular implant set <NUM> or with a depth gauge <NUM> provided with the implant set <NUM>.

A system for calibrating a surgical handpiece system <NUM> is shown in <FIG>. In this system, a screw <NUM> and plate <NUM> from the set are used in conjunction with the measurement module <NUM> and a calibration fixture <NUM> to calibrate the measurement module <NUM> for the surgical handpiece system <NUM>.

In this system, the calibration fixture <NUM> has an elongated housing <NUM>, such as a tubular or rectangular housing, with a proximal end opening <NUM> on a proximal end <NUM> and distal end opening <NUM> on a distal end <NUM>. The housing <NUM> defines a lumen <NUM>.

The housing <NUM> contains a slider <NUM> that is freely moveable in the lumen <NUM> of the housing <NUM> in the axial directions. The proximal face of the slider <NUM> is designed to abut a distal end <NUM> of the depth measurement extension <NUM> of the measurement module <NUM>. The distal face of the slider <NUM> is designed to engage the tip of the selected screw <NUM>.

In order to use the system in in <FIG>, the depth measurement extension <NUM> may be fully extended from the measurement module <NUM>. The housing <NUM> is placed over the depth measurement extension <NUM> such that the depth measurement extension <NUM> is disposed within lumen <NUM>. Furthermore, the proximal end <NUM> of the housing <NUM> is either pressed against the end of the measurement module <NUM> or may be secured to the measurement module <NUM> using an interlocking mechanism <NUM>. While the interlocking mechanism is shown here as an interlocking recess <NUM> and protrusion <NUM>, it should be appreciated that the interlocking mechanism may also take other suitable forms.

The slider <NUM> of the calibration fixture <NUM> is situated at the distal region of the calibration fixture <NUM> and abuts the extended depth measurement extension <NUM>, referred to as starting point SP. The slider <NUM> is configured to move axially within the lumen <NUM> of the housing <NUM>. The precise movement of the slider <NUM> may be guided by wings <NUM> which may be seated within corresponding sized grooves <NUM> within the housing <NUM> to ensure smooth motion relative to the longitudinal axis of the lumen. The slider <NUM> may alternatively interact with the housing <NUM> in other ways to ensure smooth motion within the lumen <NUM> of the housing <NUM>.

The user actuates one or more user inputs on the measurement module <NUM> or surgical handpiece assembly <NUM> to operate the measurement module <NUM> in a calibration mode. This zeroes the measurement module <NUM>. The user then selects a screw <NUM> of any length and a plate <NUM> from the set to be used. The plate <NUM> is placed against the distal end <NUM> of the calibration housing <NUM> and the screw <NUM> is inserted through the distal opening <NUM> of the plate <NUM> into the distal end <NUM> of the calibration fixture <NUM>. The end of the screw <NUM> displaces the slider <NUM> and depth measurement extension <NUM> such that the slider <NUM> rests at a final position, FP, as shown in <FIG>. The display <NUM> of the measurement module <NUM> may show the resulting displacement of the measurement extension.

In the example in <FIG>, the user selected a <NUM> screw, which displaced the depth measurement extension <NUM> by <NUM>. This displacement correlates to the cortex-to-cortex bone thickness that the surgical handpiece system <NUM> measures. The difference (<NUM>) between the labelled length of selected screw <NUM> (<NUM>) and the measured displacement (<NUM>) is the length adjustment for this particular screw <NUM> and plate <NUM> set. The user may then enter a "Calibration Mode," which allows the length adjustment to be entered into the measurement module <NUM> and to be stored within a memory unit of the measurement module <NUM> for the remainder of the surgical case.

The user may then enter "Drilling Mode" through actuation of one or more user inputs on the surgical handpiece system <NUM>. While in Drilling Mode, the stored adjustment will be automatically added to the live depth measurement and the measured cortex-to-cortex value determined by the measurement module <NUM> when the user drills through bone of the patient. This technique effectively bridges the gap between the absolute measurement of the bone thickness and proper screw selection for a given system. Alternatively, the adjustment may be retained by the user to enable proper screw <NUM> selection. In other words, the user will know that he or she will need to add <NUM> to the measurement determined by the measurement module <NUM> when determining the appropriate screw length to be used.

<FIG>, and <FIG> show another calibration system that uses a surgical handpiece system <NUM> having the measurement module <NUM> interfacing with an alternative design of the calibration fixture <NUM>, with screw <NUM>, and plate <NUM> from a set to calibrate the surgical handpiece system <NUM>. Several changes and additions have been made to the system and method shown in <FIG>.

The calibration fixture <NUM> is shown with a T-shaped housing <NUM>. The T-shaped housing <NUM> provides an ergonomic benefit when holding the calibration fixture <NUM>. The T-shape also provides more surface area for the plate <NUM> to rest against.

The surgical handpiece system <NUM> and the calibration fixture <NUM> may comprise a calibration sensor assembly <NUM>. Sensor <NUM> is included in the measurement module <NUM>. The sensor <NUM> may be coupled to a processor within the measurement module <NUM> or the surgical handpiece assembly <NUM>. The processor <NUM>, based on the input signal from the sensor <NUM>, is configured to determine whether the calibration fixture <NUM> is positioned proximate to the surgical handpiece system <NUM>. The sensor assembly <NUM> may include a second component, such as an emitter, located in the calibration fixture <NUM> and configured to emit a signal to the sensor <NUM>. When the processor <NUM> determines that the calibration fixture <NUM> is positioned proximate to the measurement module <NUM>, the processor may cause the measurement module <NUM> to automatically enter the Calibration Mode. It should be appreciated that the processor may be tuned such that the processor only determines that the calibration fixture <NUM> is proximate when the calibration fixture <NUM> is less than a predetermined distance away from the measurement module <NUM>, such as less than <NUM>. In other configurations, the processor may be tuned such that the processor only determines that the calibration fixture <NUM> is abutting the measurement module <NUM>. In other configurations, the processor may cause the measurement module <NUM> to automatically enter the Calibration Mode when the measurement module <NUM> first receives power from the surgical handpiece assembly <NUM> or another portion of the surgical handpiece system <NUM>.

In one potential implementation, the sensor <NUM> comprises a magneto-resistive sensor. The sensor <NUM> may be positioned near the distal end of the measurement module <NUM> or surgical handpiece assembly <NUM>. The calibration fixture <NUM> may include an emitter <NUM> such as a magnet positioned near the proximal end <NUM> of the calibration fixture <NUM>. It is contemplated that the sensor assembly <NUM> may take other suitable forms to detect the proximity of the calibration fixture <NUM>, for example, the sensor <NUM> may take the form of a mechanical button or switch that is depressed, an RFID antenna that is triggered by a coil included on the calibration fixture <NUM>, or a capacitive sensor, or a hall effect sensor.

It is also contemplated that a plurality of emitters <NUM> may be arranged near the proximal end of the calibration fixture <NUM> to permit the sensor <NUM> to detect one or more of the plurality of emitters <NUM> when the calibration fixture <NUM> is proximate the measurement module. This feature is advantageous because the calibration fixture <NUM> may be radially oriented in a number of different positions relative to the measurement module <NUM> and the sensor <NUM> may still determine the calibration fixture <NUM> is proximate the measurement module <NUM>. In one configuration, an array of emitters <NUM> may be arranged about a proximal opening of the calibration fixture <NUM> that is configured to receive the depth measurement extension <NUM>. The array of emitters <NUM> may be circumferentially spaced such that the sensor <NUM> may detect the calibration fixture is proximate in any radial orientation of the calibration fixture <NUM> relative the measurement module <NUM>.

In other configurations, the sensor <NUM> may be coupled to the calibration fixture <NUM> near the proximal end of the calibration fixture <NUM> and the emitter <NUM> may be coupled to the measurement module <NUM> near the distal end of the module housing <NUM>.

Once the processor determines that the calibration fixture <NUM> is positioned proximate to the surgical handpiece system <NUM> based on the sensor <NUM> input signal, the processor may cause the measurement module <NUM> or surgical handpiece assembly <NUM> to enter calibration mode. Then-once measurement module <NUM> determines the length adjustment for a given plate <NUM> and screw <NUM> set through the procedure described for the system shown in <FIG> and the measurement module <NUM> stores length adjustment in the memory unit of the measurement module <NUM>-the user reenters the Drilling Mode. During the Drilling Mode the length adjustment may automatically be added to the measured displacement to inform the surgeon on proper screw selection.

It should also be appreciated that the processor <NUM> may also send a command to the measurement module <NUM> to cause the measurement module <NUM> to automatically enter the Drilling Mode when the processor <NUM> determines that the calibration fixture <NUM> is no longer positioned proximate the surgical handpiece system <NUM>. This feature could be further based on an amount of time elapsed. For example, the processor <NUM> may cause the measurement module <NUM> to reenter the Drilling Mode <NUM> seconds after the processor <NUM> determines that the calibration fixture <NUM> is no longer in proximity to the handpiece. It should be appreciated that while the description throughout refers to the measurement module <NUM> performing logical steps, those same logical steps could be performed by any component of the surgical handpiece assembly <NUM>. These steps include, but are not limited to, performing calculations, determining proximity, and entering calibration or drilling mode.

In the system in <FIG>, the calibration housing <NUM> is placed over the depth measurement extension <NUM> and is either pressed against the distal end of the surgical handpiece system <NUM> or may be secured to the surgical handpiece system <NUM> using an interlocking mechanism (not shown). The slider <NUM> of the calibration fixture <NUM> may be situated at the distal region of the lumen <NUM> of the calibration fixture <NUM> prior to insertion of the screw <NUM>. The distal end of the depth measurement extension <NUM> abuts the proximal end <NUM> of the slider <NUM>. As described above, the measurement module <NUM> may automatically enter the Calibration Mode when the processor <NUM> detects that the calibration fixture <NUM> is positioned proximate the surgical handpiece system <NUM>.

When the measurement module <NUM> enters Calibration Mode, the depth reading is zeroed and the processor <NUM> waits for further input from the displacement sensor assembly <NUM> associated with depth measurement extension <NUM>. The user is then prompted on the display <NUM> to select a screw <NUM> having a specific nominal screw length from the set, for example, <NUM>. A screw length between <NUM> and <NUM> is ideal because this length is generally included in every type of implant sets for smaller bones, such as those in the foot, as well as implant sets for larger bones, such as the femur. The bone-abutting face <NUM> of the plate <NUM> is placed against the distal end of the calibration fixture housing <NUM> and the screw <NUM> is inserted through the plate <NUM> into the distal end of the calibration fixture <NUM>. The end of the screw <NUM> contacts the distal end <NUM> of the slider <NUM> which displaces the slider <NUM> and depth measurement extension <NUM>, as shown in <FIG> and <FIG>.

In other configurations where the calibration mode has already been entered by the user input device, by the coupling of the measurement module <NUM> to the surgical handpiece assembly <NUM>, or by another manner, the screw <NUM>, plate <NUM>, and the calibration housing <NUM> may engage each other before the calibration fixture <NUM> is place proximate the measurement module <NUM>. The bone-abutting face <NUM> of the plate <NUM> is placed against the distal end of the calibration fixture housing <NUM> and the screw <NUM> is inserted through the plate <NUM> into the distal end of the calibration fixture <NUM>. The end of the screw <NUM> contacts the distal end <NUM> of the slider <NUM>. Then the calibration fixture <NUM> is placed proximate the measurement module <NUM> and the slider <NUM> displaces the depth measurement extension <NUM>. It is contemplated that the calibration fixture <NUM>, the measurement module <NUM>, the screw <NUM>, and the plate <NUM> may engage each other in a different order and correctly provide an accurate adjustment so long as the relative position and engagements remain the same as shown in the illustrated and described configurations herein.

In other configurations, the user may be directed to insert one of a number of screws having predetermined nominal lengths. The measurement module <NUM> may detect the screw <NUM> is of a certain nominal length based on the range in which the displacement of the depth measurement extension falls and the measurement module <NUM> may then determine an adjustment based on the displacement of the depth measurement extension <NUM> and the identified nominal screw length. For instance, the user may be prompted on the display <NUM> to select a screw <NUM> having either a first nominal screw length from the set or a second nominal screw length from the set. The measurement module <NUM> may automatically determine which screw was selected based on the displacement of the depth measurement extension <NUM> and range the displacement falls within. After the measurement module <NUM> determines which screw was selected the adjustment may be determined as described herein.

In some configurations, one or more adjustment parameters must be met for the measurement module <NUM> to register a final displacement of the depth measurement extension <NUM> to determine the adjustment. One adjustment parameter may be the sensor <NUM> determining the calibration fixture <NUM> is proximate the measurement module <NUM> to establish an accurate tolerance stack-up between the calibration fixture <NUM> and the measurement module <NUM>. Another adjustment parameter may be a relative position of the depth measurement extension <NUM> relative the module housing <NUM> being within a certain range. For example, if the user selects a screw <NUM> from the set that is too short to displace the slider <NUM> and/or the depth measurement extension <NUM> to a certain minimum threshold, the displacement may not be registered and the user may be required to use a longer screw <NUM>. Similarly, if the user selects a screw <NUM> from the set that is too long such that the slider has been displaced to maximum threshold, the displacement may not be registered and the user may be required to use a shorter screw <NUM>. Further, if the screw <NUM> is too long, the head of the screw may not be abutting the plate <NUM> if the slider <NUM> is at a proximal end of the lumen <NUM> and the screw <NUM> is longer than the distance between the distal end of the slider <NUM> and the distal end of the calibration housing <NUM>. Still another adjustment parameter may be that the position of the depth measurement extension <NUM> relative to the calibration housing <NUM> remain constant for a certain duration of time. For instance, the user may be required to hold the calibration housing <NUM> steady for a minimum amount of time, for example <NUM> to <NUM> seconds, in order for the measurement module <NUM> to register the final displacement from the selected screw.

The measurement module <NUM> automatically calculates and stores the length adjustment. The calculation is possible due to a mechanical stack-up of known and measured distances specified in <FIG>. Dimension A is the length of the calibration fixture <NUM> from proximal <NUM> to distal end <NUM>, which is also the space between the distal end of the measurement module <NUM> and the bone-abutting face <NUM> of the plate <NUM>. Dimension B is the distance from the distal end of the measurement module <NUM> to the distal end of the depth measurement extension <NUM>, which is measured using the measurement module <NUM>. Dimension C is the length of the slider <NUM>. Finally, Dimension D is the unknown distance from the tip of the selected screw to the bone-abutting face <NUM> of the plate <NUM>.

The measurement module <NUM> can simply subtract Dimension B and Dimension C from Dimension A to determine Dimension D, the displacement caused by the insertion of the screw <NUM>. Dimension D correlates to the cortex-to-cortex bone thickness, if screw <NUM> were inserted into bone, instead of the calibration fixture <NUM>. Since the nominal length of screw <NUM> is also known, the measurement module <NUM> can determine the adjustment by subtracting Dimension D from the nominal screw length, and automatically saving the length adjustment for the duration of the surgical case into the memory unit. In the alternative (or in addition to), the adjustment could be reported to the user with the display <NUM> or speaker or both. The adjustment may be rounded. For example, because sets of screws <NUM> are provided in <NUM>- or <NUM>-mm increments, the measurement module <NUM>, may round the outputted recommended screw length to the nearest mm or automatically round up or down to the next mm or next even mm.

Certain applications may benefit from ensuring that the screw is long enough to fully penetrate the bone, as a result in these instances rounding up may be preferable. While other operations where there is greater danger of damaging surrounding tissue with a protruding screw tip, rounding down may be preferable. The surgical handpiece system <NUM> may receive information regarding the planned procedure and modify its calculation of a recommended screw length accordingly.

In an exemplary calculation, based on the system shown in <FIG>, a user may be directed to insert a screw <NUM> with a nominal length of <NUM>. This may yield a Dimension D of <NUM>. The adjustment is <NUM> (i.e. the difference between the <NUM> displacement, Dimension D, and the <NUM> nominal value). The <NUM> adjustment is stored. Then when drilling is completed if a cortex to cortex bone measurement is determined to be <NUM>, the measurement module <NUM> will output a recommended screw length of <NUM>.

Calculation by the processor instead of by hand further increases accuracy of the adjustment, as it permits additional significant figures to be included in the adjustment.

Referring to <FIG> and <FIG>, an alternative configuration of the calibration fixture <NUM> is illustrated. It should be appreciated that the various configurations of the calibration fixture <NUM> may include similar elements to those shown in <FIG> that may be identified by reference numerals that are incremented by <NUM>. It should be understood that those elements including reference numerals which are incremented by <NUM> can have the same features as described above.

<FIG> and <FIG> show another calibration system that uses a surgical handpiece system <NUM> having the measurement module <NUM> interfacing with an alternative design of the calibration fixture <NUM>, with screw <NUM>, and plate <NUM> from a set to calibrate the surgical handpiece system <NUM>.

Similar to the calibration fixture <NUM> of <FIG>, the calibration fixture <NUM> is shown with a T-shaped housing <NUM>. The T-shaped housing <NUM> provides an ergonomic benefit when holding the calibration fixture <NUM>. The T-shape also provides more surface area for the plate <NUM> to rest against.

Another similarity to the calibration fixture <NUM> shown in <FIG> is a calibration sensor assembly (not shown). A sensor <NUM> is coupled to a processor within the measurement module <NUM> or surgical handpiece assembly <NUM>. The processor <NUM>, based on the input signal from the sensor <NUM>, is configured to determine whether the calibration fixture <NUM> is positioned proximate to the surgical handpiece system <NUM>. The sensor assembly may include a second component located in the calibration fixture <NUM> and configured to emit a signal to the sensor <NUM>. When the processor <NUM> determines that the calibration fixture <NUM> is positioned proximate to the measurement module <NUM>, the processor causes measurement module <NUM> to automatically enter the Calibration Mode. It should be appreciated that the processor may be tuned such that the processor only determines that the calibration fixture <NUM> is proximate when the calibration fixture <NUM> is less than a predetermined distance away from the measurement module <NUM>, such as less than <NUM>.

In one potential implementation, the sensor <NUM> comprises a magneto-resistive sensor (such as a hall-effect sensor). The sensor <NUM> may be positioned near the distal end of the measurement module <NUM> or surgical handpiece assembly <NUM>. The calibration fixture <NUM> may include a magnet <NUM> positioned near the proximal end <NUM> of the calibration fixture <NUM>. It is contemplated that the sensor assembly <NUM> may take other suitable forms to detect the proximity of the calibration fixture <NUM>, for example, the sensor <NUM> may take the form of a mechanical button or switch that is depressed, an RFID antenna that is triggered by a coil included on the calibration fixture <NUM>, or a capacitive sensor.

Once the processor determines that the calibration fixture <NUM> is positioned proximate to the surgical handpiece system <NUM> based on the sensor <NUM> input signal, the processor causes the measurement module <NUM> or surgical handpiece assembly <NUM> to enter calibration mode. Then-once measurement module <NUM> determines the length adjustment for a given plate <NUM> and screw <NUM> set through the procedure described for the system shown in <FIG> and the measurement module <NUM> stores length adjustment in the memory unit of the measurement module <NUM>-the user reenters the Drilling Mode. During Drilling Mode, the length adjustment may automatically be added to the measured displacement to inform the surgeon on proper screw selection.

The calibration fixture housing <NUM> may be placed over the depth measurement extension <NUM> and may be either pressed against the distal end of the surgical handpiece system <NUM> or may be secured to the surgical handpiece system <NUM> using an interlocking mechanism (not shown). The slider <NUM> of the calibration fixture <NUM> is situated at the distal region of the lumen <NUM> of the calibration fixture <NUM> prior to insertion of the screw <NUM>. The distal end of the depth measurement extension <NUM> abuts the proximal end <NUM> of the slider <NUM>. As described above, the measurement module <NUM> automatically may enter a calibration mode when the processor <NUM> detects that the calibration fixture <NUM> is positioned proximate the surgical handpiece system <NUM>. When the measurement module <NUM> enters Calibration Mode, the depth reading is zeroed and the processor <NUM> waits for further input from the displacement sensor assembly <NUM> associated with depth measurement extension <NUM>. The user is then prompted on the display <NUM> to select a screw <NUM> having a specific nominal screw length from the set. The bone-abutting face <NUM> of the plate <NUM> is placed against the distal end of the calibration fixture housing <NUM> and the screw <NUM> is inserted through the plate <NUM> into the distal end of the calibration fixture <NUM>. The end of the screw <NUM> contacts the distal end <NUM> of the slider <NUM> which displaces the slider <NUM> and depth measurement extension <NUM>.

The distal end of the calibration housing <NUM> has a distal surface that may include a ridge <NUM> designed to have a curvature similar to a bone and therefore closely engage a bone-abutting face <NUM> of the plate <NUM>. This ridge <NUM> is an optional improvement of the calibration housing <NUM>. Instead of a ridge, the entire distal surface of the calibration housing <NUM> may be curved or flat.

The slider <NUM> may include a biasing mechanism <NUM> configured to abut a sidewall of the calibration housing <NUM> that defines the lumen <NUM> of the calibration housing <NUM>. The biasing mechanism prevents the slider <NUM> from moving freely within the lumen <NUM> of the calibration housing. It is appreciated that while free movement of the slider <NUM> is restricted, the slider <NUM> may still be moved via user manipulation as described above. The biasing mechanism <NUM> may comprise a spring-loaded plunger. It is contemplated that other biasing mechanisms may be used to abut the sidewall of the calibration housing <NUM> to prevent otherwise free movement of the slider <NUM> within the lumen <NUM> of the calibration housing <NUM> The spring-loaded plunger may comprise a main body and a ball (or in some cases a pin) at least partially received within a recess of the main body. The ball is movably coupled to the main body to project outwardly from the main body toward a sidewall of the calibration housing <NUM>. A spring positioned within the recess of the main body is configured to apply a constant force against the ball to bias the ball toward the sidewall of the calibration housing <NUM>. Engagement of the ball against the sidewall of the calibration housing <NUM> acts to prevent free movement of the slider <NUM> within the lumen <NUM>.

An alternative housing for the above-described automated calibration is disclosed in <FIG>. Instead of a T-shaped housing <NUM> (<FIG>) and T-shaped housing <NUM> (<FIG>), housing <NUM> is used. The depth measurement extension <NUM>, is still inserted into a first receptacle <NUM> in the housing <NUM>. The screw <NUM> is inserted into a plate <NUM> and the set is inserted into a second receptacle <NUM> in the housing <NUM>. The screw head is kept in place with a centering spring <NUM>. The second receptacle <NUM> is open along a proximal end <NUM> of the calibration fixture <NUM> and along the side <NUM>. Once the screw <NUM> is inserted through plate <NUM>, both may be placed in the second receptacle <NUM> through the side opening <NUM> of the calibration fixture <NUM>. Finally, a pocket <NUM> may be added to the distal end of the surgical handpiece assembly <NUM> or measurement module <NUM> to better secure the screw <NUM> tip to prevent movement during calibration.

In this configuration, the measurement module <NUM> may more directly calculate the Dimension D, the distance from the proximal end of the plate to the distal end of the measurement module <NUM>, as the displacement of the depth measurement extension <NUM> is known and the location of the proximal end of the plate is known relative to the distal end of the depth measurement extension <NUM>. In other words, Dimension E-the known distance from the distal end of the depth measurement extension <NUM> to the bone-abutting face <NUM> of the plate <NUM>-may be subtracted from Dimension F-the known distance from the distal end of the depth measurement extension <NUM> to the pocket <NUM>-to determine Dimension D. Again, because nominal length of the selected screw <NUM> is known adjustment may be determined by subtracting the Dimension D from the nominal length of the screw <NUM>, and the adjustment may be automatically saved for the duration of the surgical case. In the alternative, the adjustment could be reported to the user.

<FIG> depicts a system that may be used to determine the adjustment of the screw <NUM> and plate <NUM> set. This system relies on the depth gauge <NUM> from the set to be used (<FIG>) and plate <NUM> from the set to be used, along with a calibration block <NUM> to determine the adjustment. The calibration block <NUM> is elongated with rounded edges. The illustrated calibration block <NUM> was designed to fit easily within one hand, but could have several shapes, including a T shape or square corners and edges. In addition, the calibration block <NUM> has a top surface <NUM> that includes a ridge <NUM> designed to have a curvature similar to a bone and therefore closely engage a bone-abutting face <NUM> of the plate <NUM>. This ridge <NUM> is an optional improvement of the calibration block <NUM>. Instead of a ridge the entire top surface <NUM> of the calibration block <NUM> may be curved or flat. In addition, the calibration block <NUM> includes two holes, a smaller hole <NUM> and a larger hole <NUM>. The calibration block <NUM> may include only one hole or more than two holes. The varying sizes of the smaller hole <NUM> and larger hole <NUM> are to provide a fit that is just larger than the depth gauge <NUM> provided with the screw <NUM> and plate <NUM> set. Each of the smaller hole <NUM> and the larger hole <NUM> have a known depth. In <FIG>, both holes <NUM>/<NUM> have a depth of <NUM>. Alternative designs with different depths may be used. For example, it may be useful to provide smaller holes with shorter depths to be used with depth gauges <NUM> provided with screw <NUM> and plate <NUM> sets for bones of the hands and feet. Larger holes may have longer depths, causing the calibration block <NUM> to have more of a triangular shape along its side profile. The calibration block <NUM> holes may also be labeled with the depth of the hole. The bottom surface <NUM> includes a raised edge <NUM> inside a depression <NUM> around each of the smaller and larger holes <NUM>, <NUM>. This raised edge <NUM> and the depression <NUM> each provide an improved surface for a hook of a depth gauge <NUM> to be held steady but are both also optional.

Determination of the adjustment for the orthopedic screw <NUM> and plate <NUM> set with the calibration block may be done by: Laying the plate <NUM> over the appropriate hole, as shown in <FIG>, the smaller hole <NUM> is used in this instance. The selected plate <NUM> should be set over the calibration block <NUM> in the same fashion it would be set over the bone during implantation. The bone-abutting face <NUM> should be placed such that it contacts top surface <NUM> of the calibration block <NUM>. The depth gauge <NUM> is then inserted through the smaller hole <NUM>. The hooked end <NUM> of the depth gauge <NUM> rests against the bottom surface <NUM> of the calibration block <NUM>. The user than obtains a screw length from the measurement markings <NUM> of the depth gauge <NUM>.

In this case, the nominal screw length is shown as <NUM> on depth gauge <NUM> in <FIG>. Thus, the adjustment is <NUM> - <NUM> hole depth or <NUM>. The user may retain the <NUM> adjustment and add the adjustment to the output of the measurement module <NUM> after drilling. Alternatively, the user may supply the adjustment to the surgical handpiece system <NUM> so that the outputted recommended screw length is automatically based on the nominal screw length from the manufacturer. The user may be prompted to provide the adjustment via the display <NUM> of the surgical handpiece system <NUM> prior to each case. A memory of the surgical handpiece system <NUM> would then store the adjustment for the duration of the surgical case.

Referring to <FIG>, an alternative configuration of the calibration block <NUM> is illustrated. It should be appreciated that the various configurations of the calibration block <NUM> may include similar elements to those shown in <FIG> that may be identified by reference numerals that are incremented by <NUM>. It should be understood that those elements including reference numerals which are incremented by <NUM> can have the same features as described above.

<FIG> depicts a system that may be used to determine the adjustment of the screw <NUM> and plate <NUM> set. This system relies on the depth gauge <NUM> from the set to be used (<FIG>) and plate <NUM> from the set to be used, along with a calibration block <NUM> to determine the adjustment. The calibration block <NUM> is elongated with rounded edges. The illustrated calibration block <NUM> was designed to fit easily within one hand, but could have several shapes, including a T shape or square corners and edges. Further, the calibration block <NUM> comprises contoured sides to assist the user in grasping the calibration block <NUM>. In addition, the calibration block <NUM> has a top surface <NUM> that includes a ridge <NUM> designed to have a curvature similar to a bone and therefore closely engages a bone-abutting face <NUM> of the plate <NUM>. This ridge <NUM> is an optional improvement of the calibration block <NUM>. Instead of a ridge, the entire top surface <NUM> of the calibration block <NUM> may be curved or flat. In addition, the calibration block <NUM> includes a hole <NUM>. The calibration block <NUM> may include more than one hole. The hole <NUM> has a known depth.

Determination of the adjustment for the orthopedic screw <NUM> and plate <NUM> set with the calibration block <NUM> may be done by: Laying the plate <NUM> over the hole <NUM>. The selected plate <NUM> should be set over the calibration block <NUM> in the same fashion it would be set over the bone during implantation. The bone-abutting face <NUM> should be placed such that it contacts top surface <NUM> of the calibration block <NUM>. The depth gauge <NUM> is then inserted through the hole <NUM>. The hooked end <NUM> of the depth gauge <NUM> rests against a bottom surface <NUM> of the calibration block <NUM>. The user than obtains a screw length from the measurement markings <NUM> of the depth gauge <NUM>.

The calibration block <NUM> may define a cavity <NUM> to reduce the weight of the calibration block <NUM>. The cavity <NUM> being open at two ends advantageously allows for easier cleaning of the cavity. However, it is contemplated that the cavity <NUM> may instead be closed at one end such that the cavity creates a blind hole.

During certain surgical procedures it may be desirable to insert a screw <NUM> or other implant at an oblique angle into a patient's bone. In such a procedure, a suitable selection of a screw length for the procedure may require the nominal screw length to be further compensated. In some procedures, a head of the screw <NUM> may not seat fully into the bevel on the proximal side of the bone plate <NUM> or fully parallel to the outer surface of a proximal cortex <NUM> (see <FIG>) of the patient's bone when inserted at an oblique angle. For example, during a procedure requiring drilling through proximal and distal cortex, when the screw is inserted at an oblique angle, the head of the screw <NUM> may abut a different portion of the plate <NUM> than what the head of the screw would abut if the screw was orthogonal to the hole of the plate, which may prevent the screw <NUM> from being fully seated in the plate hole. If the head of the screw <NUM> is not fully seated into the plate hole and no compensation took place, the selected screw length output by the measurement head may be shorter than desired and during the procedure, the screw <NUM> may not be inserted through or to the distal cortex <NUM>. By adding a compensation length based on the angle at which the screw <NUM> is inserted, the possibility that a screw <NUM> will be too short is mitigated. This compensation length may be in addition to the adjustment length provided from calibration of the surgical handpiece system <NUM> for various combinations of plates <NUM> and screws <NUM> as described above. In other words, the suitable screw length may be selected by calibrating the surgical handpiece system <NUM> for the specific screw <NUM> type and plate <NUM> selected and by compensating the calibrated screw length value for the angle at which the screw <NUM> is inserted. It is contemplated that in some configurations where calibration is not necessary or when calibration is not otherwise performed for the specific screw type or plate, that the nominal screw length may still be compensated for the angle at which the screw <NUM> is inserted.

According to the invention and referring to <FIG>, the surgical handpiece assembly <NUM> comprises a sensor <NUM> configured to generate an orientation signal responsive to orientation of the surgical handpiece assembly <NUM> and more specifically the orientation of the depth measurement extension <NUM> and the measurement axis MX the depth measurement extension <NUM> extends along. The controller <NUM> is configured to receive the signal from the sensor <NUM> and determine the suitable screw length for bone fixation based on the signal from the sensor <NUM>. The sensor <NUM> may be an accelerometer, a gyroscopic sensor, a stereoscopic sensor, or another sensor configured to generate signals to the controller <NUM> responsive to the orientation of the surgical handpiece assembly <NUM>. The sensor <NUM> may be coupled to the module housing <NUM> to be releasably attached to the handpiece housing assembly <NUM>. Alternatively, the sensor <NUM> may be coupled to the handpiece housing assembly <NUM> in configurations where the module housing <NUM> is integral with the handpiece housing assembly <NUM>.

Referring to <FIG> and <FIG>, the angle at which the surgical handpiece assembly <NUM> drills the hole may be used to determine the angle that the screw <NUM> is to be inserted to find the compensation length. The depth measurement extension <NUM> may be movable by a user between a reference orientation <NUM> (shown in <FIG>) and a drilling orientation <NUM> (shown in <FIG>). In the reference orientation <NUM>, the measurement axis MX is aligned with a reference axis RX extending through a hole <NUM> defined by the bone plate <NUM>. In many configurations, the reference axis RX is perpendicular to one or both the bone <NUM> and the bone plate <NUM>. In the drilling orientation <NUM>, the measurement axis MX of the depth measurement extension <NUM> is at an oblique angle relative to the reference axis RX. This oblique angle is the drilling angle that the screw <NUM> will later be inserted at.

The controller <NUM> may be configured to receive the orientation signal from the sensor <NUM> corresponding to the depth measurement extension <NUM> being in the drilling orientation <NUM>. The controller <NUM> may then be configured to determine the drilling angle of the depth measurement extension <NUM> based on the orientation signal. Then, the controller <NUM> may be configured to determine a compensation length based on the drilling angle. The controller <NUM> may then use the compensation length to compensate either a nominal screw length or a calibrated screw length responsive to the drilling angle to determine a suitable screw length for bone fixation.

As shown in <FIG>, in configurations where the sensor <NUM> comprises a gyroscopic sensor <NUM>, the gyroscopic sensor <NUM> may be coupled to the module housing <NUM>. In other configurations, the gyroscopic sensor <NUM> is coupled to the handpiece housing assembly <NUM>. The gyroscopic sensor <NUM> may generate the orientation signal responsive to angular velocity. The orientation signal may comprise angular velocity values in at least two of X, Y, and Z directions (see <FIG> and <FIG>) that correspond to a change in orientation of the depth measurement extension <NUM> as the depth measurement extension <NUM> moves from the reference orientation <NUM> to the drilling orientation <NUM>. The controller <NUM> may be configured to determine the drilling angle of the depth measurement extension <NUM> by integrating the angular velocity values over a duration of time. The duration of time may begin when the reference orientation <NUM> is established and the duration of time may end when the drilling orientation <NUM> is established. By integrating the angular velocity values, the controller <NUM> may then determine the change in orientation of the depth measurement extension <NUM> from the reference orientation <NUM> to the drilling orientation <NUM>, and thus the controller <NUM> may determine the drilling angle between the reference and the drilling orientations <NUM>, <NUM>.

The user may operatively engage a user input of the surgical handpiece system <NUM> to establish the reference orientation <NUM> and the drilling orientation <NUM>. Alternatively, the controller <NUM> may be configured to generate signals responsive to certain parameters to establish the reference and drilling orientations <NUM>, <NUM>. Some of these parameters are discussed below. Establishing the reference and drilling orientations <NUM>, <NUM> may promote controller <NUM> accuracy in determining the drilling angle based on the user's deliberate orientation/manipulation of the surgical handpiece assembly <NUM> relative to the bone plate <NUM>. Said differently, the possibility that the controller <NUM> determines a false drilling angle from the orientation signal generated from the sensor <NUM> is mitigated when the user operatively engages the surgical handpiece assembly <NUM> to establish the reference and the drilling orientations <NUM>, <NUM> or when certain parameters are met to establish the reference and drilling orientations <NUM>, <NUM>.

As stated above, the displacement sensor assembly <NUM> may be configured to generate a displacement signal to the controller <NUM> responsive to displacement of the drill bit <NUM> relative to the depth measurement extension <NUM> during or leading up to the drilling process. One or both the reference and drilling orientations <NUM>, <NUM> may be established by the controller <NUM> (i) receiving the displacement signal, and (ii) determining the drill bit <NUM> has been displaced relative to the depth measurement extension <NUM> by a predetermined distance.

Referring to <FIG>, one configuration of the surgical handpiece assembly <NUM> is shown before and during the drilling process. Although <FIG> illustrate a bone plate <NUM> being disposed on the outer surface of the proximal cortex <NUM> of the bone <NUM>, it is contemplated that the drilling angle may also be determined when a bone plate <NUM> is absent. In <FIG>, the surgical handpiece assembly <NUM> is spaced from the bone plate <NUM> and the depth measurement extension <NUM> is not yet in the reference orientation <NUM>. In <FIG> (corresponds to <FIG>), the depth measurement extension <NUM> is shown in the reference orientation <NUM>. As the depth measurement extension <NUM> is moved from its position shown in <FIG> to its position shown in <FIG>, the depth measurement extension <NUM> is displaced relative to the drill bit <NUM>. The controller <NUM> may be configured to receive a displacement signal responsive to displacement of the depth measurement extension <NUM> relative to the drill bit <NUM> and determine the depth measurement extension <NUM> is in the reference orientation <NUM>. Establishing the reference orientation <NUM> may provide a "zero offset" or baseline from which the drilling angle is determined. For instance, in the configuration including a gyroscopic sensor <NUM>, the gyroscopic sensor <NUM> may begin generating signals corresponding to angular velocity in at least two of X, Y, and Z directions (see <FIG> and <FIG>) when the reference orientation <NUM> is established.

In <FIG>, the surgical handpiece assembly <NUM> is in line with the drilling angle (corresponding to <FIG>), however, the drilling orientation <NUM> of the depth measurement extension <NUM> may not yet have been established. In <FIG>, the depth measurement extension <NUM> is shown in the drilling orientation <NUM>. As the depth measurement extension <NUM> is moved from its position shown in <FIG> to its position shown in <FIG>, the depth measurement extension <NUM> is displaced relative to the drill bit <NUM>. The controller <NUM> may be configured to receive a displacement signal responsive to displacement of the depth measurement extension <NUM> relative to the drill bit <NUM> and determine the depth measurement extension <NUM> is in the drilling orientation <NUM>. Although <FIG> shows the drill bit <NUM> has been displaced through the proximal cortex <NUM> in the drilling orientation <NUM>, it is contemplated that the drill bit <NUM> may not need to enter to such a depth in the bone <NUM> for the controller <NUM> to determine the depth measurement extension <NUM> is in the drilling orientation <NUM>. Instead, the controller <NUM> may determine the depth measurement extension <NUM> is in the drilling orientation <NUM> when the displacement of the depth measurement extension <NUM> relative the drill bit <NUM> has exceeded a predetermined displacement (e.g., <NUM> in bone <NUM>). In the configuration including the gyroscopic sensor <NUM>, the gyroscopic sensor <NUM> may cease generating signals corresponding to angular velocity when the drilling orientation <NUM> is established. As stated above, the controller <NUM> may then integrate the angular velocity values over the duration of time between when the reference orientation <NUM> was established and when the drilling orientation <NUM> was established.

In another configuration, one or both the reference and the drilling orientations <NUM>, <NUM> may be established by motor state signals. The surgical handpiece assembly <NUM> may comprise another sensor <NUM> (see <FIG>) configured to generate a motor state signal to the controller <NUM> responsive to a state of the motor <NUM>. One or both the reference and drilling orientations <NUM>, <NUM> may be established by the controller <NUM> determining that the state of the motor <NUM> has changed from an idle state to a running state. In one configuration, the motor state signal corresponds to a torque generated by the motor <NUM>. The motor <NUM> does not generate torque in the idle state and the motor <NUM> generates torque in the running state. In another configuration, the motor state signal corresponds to a rotational speed of the motor <NUM>. The motor <NUM> operates at a rotational speed below a rotational speed threshold in the idle state and the motor <NUM> operates at another rotational speed above the rotational speed threshold in the running state. In one configuration, the sensor <NUM> may be an accelerometer disposed in the measurement module <NUM>. Alternatively, a single sensor may be used to determine both the angular offset and the motor state.

In one exemplary configuration, the user may be orienting the depth measurement extension <NUM> to the drilling orientation <NUM> from the reference orientation <NUM>. The drilling orientation <NUM> may be established when the controller <NUM> determines from the motor state signal that the motor <NUM> has changed from the idle state to the running state.

In another configuration, one or both the reference and the drilling orientations <NUM>, <NUM> may be established by actuation of the trigger <NUM> (user input device <NUM> above). The trigger <NUM> may be used to generate a trigger signal responsive to actuation of the trigger <NUM> by the user to the controller <NUM> for operating the motor <NUM> to generate torque. One or both the reference and drilling orientations <NUM>, <NUM> may be established by the controller <NUM> determining that the trigger <NUM> has been actuated. In one exemplary configuration, the user may be orienting the depth measurement extension <NUM> to the drilling orientation <NUM> from the reference orientation <NUM>. The drilling orientation <NUM> may be established when the controller <NUM> determines from the trigger signal that the trigger <NUM> has been actuated.

In still another configuration, one or both the reference and drilling orientations <NUM>, <NUM> may be established by a user input device <NUM>. The surgical handpiece assembly <NUM> may comprise the user input device <NUM> separate from the user input device <NUM> (trigger) used to operate the motor <NUM> above. The user input device <NUM> may be coupled to a measurement head, such as module housing <NUM> as illustrated in <FIG>. Alternatively, the user input device <NUM> may instead be coupled to the handpiece housing assembly <NUM>. The user input device <NUM> may be operable to generate a first reference signal to the controller <NUM> to establish that the measurement axis MX is aligned with the reference axis RX and to establish the depth measurement extension <NUM> is in the reference orientation <NUM>. For example, the user may orient the depth measurement extension <NUM> to the reference orientation <NUM> and then actuate (e.g., press a button) the user input device <NUM> to generate the first reference signal to the controller <NUM>. The controller <NUM> may then determine the depth measurement extension <NUM> is in the reference orientation <NUM>. Likewise, the same or another user input device may be actuated a second time to generate the same or a second reference signal to the controller <NUM> to establish the drilling orientation <NUM>.

In another configuration, one or both the reference and the drilling orientations <NUM>, <NUM> may be established by the controller <NUM> determining the orientation signal from the sensor <NUM> of the depth measurement extension <NUM> have remained generally constant for a predetermined duration of time such that the depth measurement extension <NUM> has remained static. In one exemplary configuration, the user may be orienting the depth measurement extension <NUM> to the drilling orientation <NUM> from the reference orientation <NUM>. The drilling orientation <NUM> may be established when the controller <NUM> determines from the orientation signal that the depth measurement extension <NUM> has remained static for more than a predetermined duration of time. The predetermined duration of time may vary, but exemplary times are for at least <NUM>, <NUM> or <NUM> seconds.

It is contemplated that one or both the reference and drilling orientations <NUM>, <NUM> may be established in a different manner than specified above. It is also contemplated that one or both the reference and drilling orientations <NUM>, <NUM> may be established using a combination of the configurations described above. For example, in <FIG>, the surgical handpiece assembly <NUM> is spaced from the bone plate <NUM> and the depth measurement extension <NUM> is not yet in the reference orientation <NUM>. After the user manipulates the surgical handpiece assembly <NUM> so that the depth measurement extension <NUM> is in the reference orientation <NUM> shown in <FIG> (corresponds to <FIG>), the user may actuate the user input device <NUM> to generate a reference signal to the controller <NUM> and the controller <NUM> may determine that the reference orientation <NUM> is established. The user may then manipulate the depth measurement extension <NUM> to the orientation shown in <FIG> (corresponds to <FIG>) and begin drilling through the proximal cortex <NUM>. After the drill bit <NUM> has exceeded a predetermined displacement relative to the depth measurement extension <NUM>, the controller <NUM> may determine that the drilling orientation <NUM> has been established.

After the controller <NUM> determines the drilling angle, the controller <NUM> may determine the compensation length by using a function that is at least partially dependent on the drilling angle. The function may also be dependent on the nominal screw length or the calibrated screw length including the adjustment length. Alternatively, the controller <NUM> may determine the compensation length by using a look-up table that is at least partially dependent on the drilling angle. More specifically, the look-up table may associate particular ranges of drilling angles with a single compensation length. In one exemplary configuration, a drilling angle between <NUM> (zero) degrees and <NUM> (ten) degrees may output a compensation length of <NUM> (zero mm); a drilling angle greater than or equal to <NUM> (ten) degrees and less than <NUM> (forty-five) degrees may output a compensation length of <NUM> (one mm); and a drilling angle greater than or equal to <NUM> (forty-five) degrees may output a compensation length of <NUM> (two mm). Other ranges for drilling angles and associated compensation lengths are contemplated. Alternatively, the controller <NUM> may determine the compensation length by interpolating between discrete angles using a look-up table. More specifically, the look-up table may associate discrete drilling angle values with compensation lengths such that each drilling angle value listed in the look-up table corresponds to a single compensation length and if an observed drilling angle is between two drilling angle values in the look-up table, the controller <NUM> may determine the compensation length by interpolating between the compensation lengths corresponding to the two drilling angle values. For instance, the look-up table may provide a compensation length of <NUM> for a drilling angle of <NUM> (ten) degrees and a compensation length of <NUM> for a drilling angle of <NUM> (thirty) degrees. When the drilling angle is at <NUM> (twenty) degrees, the controller <NUM> may determine that compensation length is <NUM>. It is contemplated that interpolation may be accomplished using a linear relationship as described in the example or another function dependent on drilling angle. The look-up table may also be dependent on the nominal screw length or the calibrated screw length including the adjustment length. The look-up table and other computer software described herein may be stored on memory in the measurement module <NUM> or in memory associated with a remote device, such as a tablet, that is in wireless communication with the measurement head.

After the compensation length is determined, the controller <NUM> may be configured to output a suitable screw length for bone fixation that is dependent upon the nominal screw length (determined from displacement of the depth measurement extension <NUM> after drilling) and one or both of the compensation length (determined from the drilling angle) and the adjustment length (determined during calibration for the specific plate <NUM> and screw <NUM> type selected).

Referring to <FIG>, the surgical handpiece system <NUM> may comprise a remote device <NUM> having a display <NUM>. The remote device <NUM> may be configured to generate signals to and receive signals from the surgical handpiece assembly <NUM>. The remote device <NUM> in <FIG> comprises a tablet. However, it is contemplated that the remote device <NUM> could instead comprise a smart-phone, a laptop, a workstation, or a desktop computer. One or both the display <NUM> on surgical handpiece assembly <NUM> and the display <NUM> on the remote device <NUM> may output one or more of the suitable screw length, the compensation length, the adjustment length, the nominal screw length, the displacement of the depth measurement extension <NUM>, the drilling angle, the specific plate <NUM> used, the specific screw <NUM> type used, and other information associated with the surgical handpiece system <NUM>.

In one configuration, one or both the surgical handpiece assembly <NUM> and the remote device <NUM> comprise a user input device (not shown) for entering or selecting information to the controller <NUM>. The user may enter or select an oblique drilling factor in place of the compensation length for compensating the nominal screw length or the calibrated screw length including the adjustment length. The controller <NUM> may be configured to determine a suitable screw length based on the nominal screw length (determined from displacement of the depth measurement extension <NUM> after drilling), the adjustment length (determined during calibration for the specific plate <NUM> and screw <NUM> type selected), and the oblique drilling factor entered/selected by the user. The suitable screw length may be output to one or both the display <NUM> on surgical handpiece assembly <NUM> and the display <NUM> on the remote device <NUM>.

It will be further appreciated that the terms "include," "includes," and "including" have the same meaning as the terms "comprise," "comprises," and "comprising. " Moreover, it will be appreciated that terms such as "first," "second," "third," and the like are used herein to differentiate certain structural features and components for the non-limiting, illustrative purposes of clarity and consistency. In this application, including the definitions below, the term "controller" may be replaced with the term "circuit. " The term "controller" may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip.

The controller may include one or more interface circuits. In some examples, the interface circuit(s) may implement wired or wireless interfaces that connect to a local area network (LAN) or a wireless personal area network (WPAN). Examples of a LAN are Institute of Electrical and Electronics Engineers (IEEE) Standard <NUM>-<NUM> (also known as the WIFI wireless networking standard) and IEEE Standard <NUM>-<NUM> (also known as the ETHERNET wired networking standard). Examples of a WPAN are the BLUETOOTH wireless networking standard from the Bluetooth Special Interest Group and IEEE Standard <NUM>.

The controller may communicate with other controllers using the interface circuit(s). Although the controller may be depicted in the present disclosure as logically communicating directly with other controllers, in various implementations the controller may actually communicate via a communications system. The communications system includes physical and/or virtual networking equipment such as hubs, switches, routers, and gateways. In some implementations, the communications system connects to or traverses a wide area network (WAN) such as the Internet. For example, the communications system may include multiple LANs connected to each other over the Internet or point-to-point leased lines using technologies including Multiprotocol Label Switching (MPLS) and virtual private networks (VPNs).

In various implementations, the functionality of the controller may be distributed among multiple controllers that are connected via the communications system. For example, multiple controllers may implement the same functionality distributed by a load balancing system. In a further example, the functionality of the controller may be split between a server (also known as remote, or cloud) controller and a client (or, user) controller.

Some or all hardware features of a controller may be defined using a language for hardware description, such as IEEE Standard <NUM>-<NUM> (commonly called "Verilog") and IEEE Standard <NUM>-<NUM> (commonly called "VHDL"). The hardware description language may be used to manufacture and/or program a hardware circuit. In some implementations, some or all features of a controller may be defined by a language, such as IEEE <NUM>-<NUM> (commonly called "SystemC"), that encompasses both codes, as described below, and hardware description.

The term shared processor circuit encompasses a single processor circuit that executes some or all code from multiple controllers. The term group processor circuit encompasses a processor circuit that, in combination with additional processor circuits, executes some or all code from one or more controllers. The term shared memory circuit encompasses a single memory circuit that stores some or all code from multiple controllers. The term group memory circuit encompasses a memory circuit that, in combination with additional memories, stores some or all code from one or more controllers.

The term memory circuit is a subset of the term computer-readable medium. The term computer-readable medium, as used herein, does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium may therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).

The apparatuses and methods described in this application may be partially or fully implemented by a special purpose computer created by configuring a general purpose computer to execute one or more particular functions embodied in computer programs. The functional blocks and flowchart elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that are stored on at least one non-transitory computer-readable medium. The computer programs may also include or rely on stored data. The computer programs may encompass a basic input/output system (BIOS) that interacts with hardware of the special purpose computer, device drivers that interact with particular devices of the special purpose computer, one or more operating systems, user applications, background services, background applications, etc..

The computer programs may include: (i) descriptive text to be parsed, such as HTML (hypertext markup language), XML (extensible markup language), or JSON (JavaScript Object Notation), (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. As examples only, source code may be written using syntax from languages including C, C++, C#, Objective C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, JavaScript®, HTML5 (Hypertext Markup Language 5th revision), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, MATLAB, SIMULINK, and Python®.

Several configurations have been discussed in the foregoing description. However, the configurations discussed herein are not intended to be exhaustive or limit the invention to any particular form. The terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations are possible in light of the above teachings and the invention may be practiced otherwise than as specifically described.

Claim 1:
A surgical handpiece system (<NUM>) configured to determine a suitable screw (<NUM>) length for bone fixation with a bone plate (<NUM>) that compensates an initial screw length value based on orientation of the surgical handpiece system (<NUM>) during a drilling process, said surgical handpiece system (<NUM>) comprising:
a surgical handpiece assembly (<NUM>) comprising:
a handpiece housing (<NUM>),
a motor (<NUM>) disposed within the handpiece housing (<NUM>) and configured to generate torque,
a depth measurement extension (<NUM>) movably coupled to the handpiece housing (<NUM>), and
a sensor (<NUM>) configured to generate an orientation signal responsive to orientation of the depth measurement extension (<NUM>);
a drill bit (<NUM>) configured to be coupled to and receive torque from the motor (<NUM>) of the surgical handpiece assembly (<NUM>); and
a processor (<NUM>) configured to receive the signal from the sensor (<NUM>) and determine the suitable screw length for bone fixation based on the signal from the sensor (<NUM>).