Patent Description:
This disclosure generally relates to medical devices. More particularly, the disclosure relates to the field of spinal surgery and spinal fixation devices.

Spinal fixation constructs are utilized to provide stability to the spine. Most often the fixation construct is used as an adjunct to fusion surgery during which adjacent vertebrae are prepared to facilitate bone growth between them. Because motion between the vertebrae tends to inhibit bone growth, the fixation constructs are employed to prevent motion so that bone can grow and achieve a solid fusion. When the position of one or more vertebrae must be adjusted to restore a more natural alignment of the spinal column, the fixation construct also serves to maintain the new alignment until fusion is achieved.

Fixation constructs of various forms are known in the art, of which, rod based fixation constructs are one of the most common. Typically a rod based construct includes multiple anchors that are coupled to a portion (e.g. the posterior elements) of two or more vertebrae and then connected by a fixation rod. The anchors further include a rod housing in which the fixation rod is captured and locked. The rod housing may be fixed, pivotably or rotatably coupled to the anchor portion and generally includes a pair of upstanding arms separated by a rod channel.

When constructing the fixation construct the surgeon must align and seat the rod in the rod channel of each anchor, an undertaking that is generally referred to as "reduction. " Reduction can be a challenge, particularly when one or more of the vertebrae to be connected are out of alignment with other vertebrae, and the reduction distance and force requirements can vary greatly from anchor to anchor. Conventional reduction procedures are heavily reliant upon the surgeon (or operator's) expertise in judging the load applied by each rod reducer on the spinal rod. In multi-level fixation procedures involving multiple vertebrae, it can be particularly challenging for the surgeon to determine which rod reducer(s) are properly loaded while engaged with the spinal rod. <CIT>, <CIT>, <CIT> and <CIT> all describe instrument known in the general art.

The needs above, as well as others, are addressed by embodiments of rod reduction instruments, spinal fixation monitoring systems, and related methods (not claimed) described in this disclosure. All examples and features mentioned below can be combined in any technically possible way.

Various implementations include rod reduction instruments, spinal fixation monitoring systems, and related methods (not claimed). Certain implementations include a rod reduction instrument that is adapted for use with a spinal fixation system and includes a sensor configured to detect a load exerted by a rod reducer on a spinal rod, along with a reduction feedback system that provides an indicator of the load exerted by the rod reducer on the spinal rod.

A rod reduction instrument adapted for use with a spinal fixation system includes: a rod reducer having a proximal end and a distal end, where the distal end of the rod reducer is configured to engage a spinal rod for seating the spinal rod into a pedicle screw receiver; a sensor configured to detect a load exerted by the rod reducer on the spinal rod during seating of the spinal rod in the pedicle screw receiver; and a reduction feedback system coupled with the sensor, the reduction feedback system configured to: receive load data indicating the load exerted by the rod reducer on the spinal rod from the sensor; and provide an indicator of the load data that is detectable by an operator of the rod reduction instrument.

A method (not claimed) includes providing feedback to an operator during a spinal fixation procedure, the spinal fixation procedure including engaging a spinal rod with a rod reducer to seat the spinal rod into a pedicle screw receiver. The method can further include: receiving, from a sensor, load data indicating a load exerted by the rod reducer on the spinal rod during seating of the spinal rod in the pedicle screw receiver; and providing an indicator of the load data that is detectable by the operator during the spinal fixation procedure.

In further particular aspects, a spinal fixation monitoring system for use in a spinal fixation procedure includes: a plurality of rod reduction instruments adapted for use with a spinal fixation system, each of the rod reduction instruments including: a rod reducer having a proximal end and a distal end, wherein the distal end of the rod reducer is configured to engage a spinal rod for seating the spinal rod into a corresponding pedicle screw receiver; and a sensor configured to detect a load exerted by the rod reducer on a portion of the spinal rod during seating of the spinal rod in the pedicle screw receiver; and a reduction feedback system coupled with the sensor of each of the rod reduction instruments, the reduction feedback system configured to: receive load data indicating the load exerted by each rod reducer on the portion of the spinal rod from a corresponding one of the sensors; and provide an indicator of the load data for at least one of the rod reducers in the plurality of rod reduction instruments, the indicator being detectable by an operator of the plurality of rod reduction instruments.

A spinal fixation system includes: a first bone anchor including a first pedicle screw and a receiver; a rod configured to be seated within the receiver of the first bone anchor; an instrument configured to couple to the first bone anchor; and a sensor coupled to the instrument and configured to determine data relating to at least one of: the first bone anchor, the rod or the instrument.

Implementations may include one of the following features, or any combination thereof.

In certain examples, the rod reduction instrument further includes a housing mounted to the proximal end of the rod reducer, where the reduction feedback system is disposed within the housing.

In some cases, the housing is: a) modular and/or disposable, b) mounted to the existing nut and is disposable, or c) mounted to any portion of the rod reducer.

In particular implementations, the reduction feedback system includes a processor and memory, the memory storing instructions which when executed, cause the processor to: compare the load data with a load threshold for the rod reducer; and provide an indicator that the load data satisfies or does not satisfy the load threshold for the rod reducer.

The load data at least partially represents an amount of torque applied to a lock screw during tightening of the lock screw within the pedicle screw receiver and a compressive force applied to the rod reducer, wherein the indicator that the load data satisfies or does not satisfy the load threshold includes an indicator of an amount that the compressive force applied to the spinal rod should be modified to satisfy the load threshold for the rod reducer, where the load threshold is based at least in part on a model that correlates clinical data representing patient-specific bone quality with screw pullout.

In certain cases, the load threshold defines a maximum acceptable load exerted by the rod reducer on the spinal rod during seating of the spinal rod in the pedicle screw receiver, wherein the maximum acceptable load is: a) approximately <NUM> kilograms to approximately <NUM> kilograms (approximately <NUM> pounds to approximately <NUM> pounds), b) approximately <NUM> kilograms to approximately <NUM> kilograms (approximately <NUM> pounds to approximately <NUM> pounds), or c) approximately <NUM> kilograms to approximately <NUM> kilograms (approximately <NUM> pounds to approximately <NUM> pounds).

The processor is further configured to: compare the load data with additional load data detected by a set of additional sensors coupled with additional rod reducers; and provide an indicator of relative loading of the rod reducer as compared with at least one of the additional rod reducers in the set.

In particular implementations, the indicator of relative loading indicates whether the rod reducer is more loaded, less loaded or equally loaded relative to the additional rod reducers in the set.

In some cases, the indicator of relative loading always includes an indicator of a least loaded rod reducer in the set.

The processor is configured to update the indicator of relative loading over time as load data for at least one of the rod reducer or the additional rod reducers in the set is updated.

In particular cases, the reduction instrument is configured for use in a multi-level reduction procedure such that the indicator of the load data comprises an indicator of relative loading of the rod reducer as compared with a set of additional rod reducers engaged with the spinal rod.

In certain implementations, the spinal fixation system includes a set of rod reduction instruments having a set of rod reducers engaged with the spinal rod, and the reduction feedback system is communicatively coupled to each of the rod reduction instruments and is configured to receive load data indicating a load exerted by each rod reducer on the spinal rod.

The set of rod reducers includes up to twenty (<NUM>) total rod reducers, arranged in subsets of ten (<NUM>) on each side of the patient's spine.

In particular cases, the reduction feedback system is further configured to provide an indicator of reduction order for the set of rod reduction instruments based on the received load data.

The indicator of reduction order includes instructions for multi-step reduction of the set of rod reduction instruments.

In some implementations, the reduction feedback system is further configured to: compare the load data from two or more of the rod reduction instruments in the set with a set of load thresholds; and provide an indicator prioritizing increased loading of a particular rod reduction instrument over at least one additional rod reduction instrument based on whether the load data from the two or more rod reduction instruments satisfies the set of load thresholds.

In certain cases, the set of load thresholds include absolute loading thresholds for each of the two or more rod reduction instruments.

Absolute loading thresholds vary based on at least one of: a) the location of a given rod reduction instrument along the patient's spine, b) the patient's anatomy, or c) the patient's bone quality.

In some implementations, the set of load thresholds include relative loading thresholds for each of the two or more rod reduction instruments.

The reduction feedback system includes an electronics compartment physically coupled with the rod reducer, the electronics compartment having at least one of a visual indication system or a tactile indication system for providing the indicator of the load data proximate to the rod reducer.

In particular implementations, the tactile indication system include at least one vibro-tactile actuator.

In some cases, the reduction feedback system further includes a controller coupled with the electronics compartment and coupled with a set of additional electronics compartments on a set of additional rod reduction instruments in the spinal fixation system, where the controller is configured to communicate with the electronics compartment and the set of additional electronics compartments either wirelessly or via a hard-wired connection.

The hard-wired connection comprises a fiber optic connection.

In certain cases, the visual indication system includes a set of lights configured to be illuminated in at least two distinct patterns to indicate distinctions in the load data, or a display configured to provide at least two distinct visual indicators of the load data.

In some implementations, the display includes a liquid-crystal display (LCD).

The rod reduction instrument further includes a power source housed in the electronics compartment and coupled with the visual indication system or the tactile indication system.

In certain implementations, the sensor is located between the proximal end and the distal end of the rod reducer.

In some cases, the rod reducer includes a multi-section shaft, and the sensor is mounted axially between distinct sections of the multi-section shaft.

In particular implementations, the sensor is coupled to the proximal end of the rod reducer.

The sensor is located in a housing with at least a portion of the reduction feedback system.

In some cases, the sensor includes at least one of: a strain gauge, pressure-sensitive film, or a capacitive sensor.

In particular implementations, the rod reduction instrument further includes a guide assembly configured to couple with the pedicle screw receiver and receive the rod reducer therein.

In certain cases, the rod reducer is configured to fully seat the spinal rod into the pedicle screw receiver and enable the spinal rod to be secured to the pedicle screw receiver.

The reduction feedback system is located at the rod reducer or at an output device separate from the rod reducer.

In particular implementations, the output device includes at least one of: a) a user interface, b) a display, c) an audio system, or d) a surgical procedure interface.

In certain cases, in the spinal fixation system, the rod reducer sits within a guide assembly that couples with the pedicle screw receiver, where the rod reducer is configured to fully seat the spinal rod into the pedicle screw receiver and enable the spinal rod to be secured to the pedicle screw receiver.

The reduction feedback system includes a housing mounted to the proximal end of each of the rod reducers for providing the indicator of the load data proximate to each of the rod reducers.

In certain cases, the sensor that is coupled to the instrument and is configured to determine data relating to at least one of: the first bone anchor, the rod or the instrument, determines data including load data.

In some implementations, the instrument configured to couple to the first bone anchor is a reduction instrument configured to seat the rod within the receiver, and the load data includes a load exerted by the reduction instrument on the rod during seating of the rod into the receiver of the first bone anchor.

The sensor that is coupled to the instrument is configured to determine data relating to at least one of: the first bone anchor, the rod or the instrument, and determines data including a tensile load between the rod and the bone anchor when the rod is at least partially seated within the bone anchor.

The sensor that is coupled to the instrument is configured to determine data relating to at least one of: the first bone anchor, the rod or the instrument, and determines data including torsional force data. In particular aspects, the instrument is a driver configured to tighten a lock screw within the receiver and lock the rod relative to the bone anchor, and the torsional force data includes a torsional force on the lock screw during tightening of the lock screw within the receiver. The instrument is a driver configured to seat the rod within the receiver and tighten a lock screw within the receiver to thereby lock the rod relative to the bone anchor, and the torsional force data includes a torsional force on the lock screw during tightening of the lock screw within the receiver.

In certain cases, the instrument configured to couple to the first bone anchor includes: a rod reduction instrument configured to seat the rod within the receiver; and a driver configured to be inserted through the rod reduction instrument to deliver and tighten a lock screw within the receiver to lock the rod relative to the bone anchor. The data includes at least one of: a load exerted by the reduction instrument on the rod during seating of the rod into the receiver of the first bone anchor, or a tensile load between the rod and the bone anchor when the rod is at least partially seated within the bone anchor. The data includes a torsional force on the lock screw during tightening of the lock screw within the receiver.

In particular implementations, the spinal fixation system further includes a navigation system communicatively coupled with the instrument and configured to detect a position of the instrument. In certain of these cases, the navigation system is configured to determine a distance moved by the instrument when the instrument changes position, and the navigation system communicates the distance to a processor.

Two or more features described in this disclosure, including those described in this summary section, may be combined to form implementations not specifically described herein.

The above presents a simplified summary in order to provide a basic understanding of some embodiments of the claimed subject matter. This summary is not an extensive overview. It is not intended to identify key or critical elements or to delineate the scope of the claimed subject matter. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

Other features, objects and benefits will be apparent from the description and drawings, and from the claims.

It is noted that the drawings of the various implementations are not necessarily to scale. The drawings are intended to depict only typical embodiments of the disclosure, and therefore should not be considered as limiting the scope of the implementations.

This disclosure provides, at least in part, a rod reduction instrument, related fixation systems and monitoring systems that beneficially incorporate a reduction feedback system to enhance efficacy of spinal fixation procedures, as well as mitigate opportunity for operator (e.g., surgeon) error in performing such procedures. The various disclosed implementations can improve patient outcomes when compared with conventional spinal fixation procedures. The disclosed implementations can provide real-time and/or post-operative feedback on reduction procedures, enhancing both current procedural outcomes as well as future surgical outcomes. In particular cases, the reduction feedback system can provide information to an operator regarding desired reduction ordering in a multi-level reduction procedure, thereby mitigating or avoiding overloading of instruments at any given time during the procedure.

Commonly labeled components in the FIGURES are considered to be substantially equivalent components for the purposes of illustration, and redundant discussion of those components is omitted for clarity.

<FIG> illustrate perspective views of example rod reduction instruments, or reducers, according to various implementations. It is understood that the disclosed implementations can be applied to a number of rod reduction instruments in various form factors. For example, additional rod reduction instruments such as those disclosed in <CIT> can benefit from the various disclosed implementations. In various implementations, the example rod reduction instruments (reducers) are used during the installation of a fixation construct <NUM> onto the spine of a patient. The fixation construct <NUM> includes anchor members <NUM> connected by a fixation rod <NUM> locked to each anchor <NUM>. An anchor <NUM> is implanted in each vertebra to be fixed by the construct <NUM>. For example, two anchors <NUM> may be used to fix two vertebrae together; three may be used to fix three vertebrae together; four may be used to fix four vertebrae together; and so on. Additionally, multiple anchors <NUM> may be used to fix each vertebrae to adjacent vertebrae (e.g., four anchors <NUM> can be used to couple two vertebrae together). The anchor <NUM> includes a bone anchor <NUM> and a housing <NUM> for capturing and locking a fixation rod <NUM>. The bone anchor <NUM> may be a bone screw suitable for stable fixation to vertebral bone (e.g. pedicle or vertebral body), as shown. The bone anchor <NUM> may also include other fixation devices (e.g. hooks, staples, clamps, etc.. The housing <NUM> has a base that attaches with the bone anchor and a pair of upstanding arms that together form a rod channel <NUM>. The housing also includes a mechanism to lock the fixation rod <NUM> in position in the rod channel <NUM>. For example, the mechanism may include a locking cap guide and advancement feature disposed on the interior face of each arm that interacts with a complementary feature on a locking cap. The base may be fixed to the anchor <NUM> or may be coupled such that the housing <NUM> can rotate in one or more directions (e.g. polyaxial). The housing <NUM> also includes one or more instrument engagement features for releasably coupling to one or more instruments during implantation. Example of anchors configured for use with the reducers described herein are shown and described in <CIT> ("Minimally Invasive Spinal Fixation System and Related Methods") and <CIT> ("Rod Reduction Assemblies and Related Methods"). The reducers described herein can be engaged to one or more of the anchors <NUM> of the fixation construct <NUM> to facilitate alignment and advancement of the rod <NUM> into the rod channel <NUM> of each anchor. In particular implementations, the fixation construct <NUM> includes a pedicle screw.

Now with reference to <FIG>, a rod reducer (or simply, reducer) <NUM> according to one example embodiment is illustrated. The reducer <NUM> is configured to couple to both arms of anchor <NUM> and impart a downward force on the rod <NUM>. The downward force on the rod acts to draw the rod <NUM> and anchor housing <NUM> together until the rod <NUM> fully seats in the rod channel <NUM>. A locking mechanism, such as locking cap may then be at least partially engaged to capture the rod <NUM> in the housing <NUM> prior to decoupling the reducer <NUM> from the anchor <NUM>. The reducer <NUM> includes a coupling unit <NUM> (<FIG>) that connects to the anchor <NUM> and a translation unit <NUM> (<FIG>) that translates relative to the coupling unit <NUM> to urge the rod <NUM> towards the anchor.

The coupling unit <NUM> includes a base member <NUM> and first and second attachment arms <NUM> that are pivotally coupled with the base member <NUM>. The base member <NUM> is an elongated, generally tubular member having a proximal portion <NUM>, a central portion <NUM>, a distal portion <NUM>, and a central lumen <NUM> (<FIG>) extending longitudinally through the entire length of the base member <NUM>. The proximal portion <NUM> includes a handle <NUM> that provides a gripping area for a user to grip the reducer <NUM>. Above the handle <NUM> is a head <NUM> (<FIG>) that allows the coupling of other instruments with the reducer <NUM>. The head <NUM> may be configured to mimic the proximal end of minimally invasive screw guides such that any instruments that engage or couple with the guides may also engage or couple with the reducer <NUM> (for example, vertebral body derotation assemblies, counter torque s, etc ). the proximal portion <NUM> can include a threaded portion formed on the interior of the proximal portion <NUM> (i.e. the proximal end of the lumen <NUM>) for threadedly engaging the translating unit <NUM>. In certain implementations, a drive knob <NUM> is located between the proximal portion <NUM> and the central portion <NUM>.

<FIG> and <FIG> illustrate a spinal fixation system <NUM> configured for introducing and building a posterior spinal fixation construct such as that described above, according to one example embodiment. According to one example, the spinal fixation system <NUM> includes a pedicle screw <NUM>, an elongated spinal rod <NUM>, and a guide assembly <NUM>. Pedicle screws <NUM> are inserted bilaterally or unilaterally into multiple vertebra across one or more levels. In additional implementations, a fixation anchor (such as those described in US Patent No. <CIT>) can be utilized in place of pedicle screw <NUM> in one or more vertebra. The spinal fixation system <NUM> may further include any of a variety of instruments configured to perform the installation and assembly of the spinal fixation construct, including by way of example a reduction instrument (also called a reducer) <NUM> shown in <FIG> and <FIG>, as well as rod inserters, compression instruments, lock screw inserters, guide adjusters, tap guides, and dilators, of which various embodiments are described in further detail in US Patent No. <CIT>.

<FIG> shows an example implementation of a rod reduction instrument (or simply, instrument) <NUM> according to various implementations. As illustrated in <FIG>, the instrument <NUM> includes a rod reducer (or simply, reducer) <NUM>, which can be similar in form and/or function to the reducer(s) described according to any implementation herein, e.g., reducer <NUM> and/or reducer <NUM>. In particular implementations, the reducer <NUM> has a proximal end <NUM> and a distal end <NUM>. The distal end <NUM> is configured to engage a spinal rod for seating the spinal rod into a pedicle screw receiver (e.g., as described with respect to <FIG>). In various implementations, the rod reducer <NUM> is configured to fully seat the spinal rod (e.g., spinal rod <NUM> in <FIG>) into the pedicle screw receiver (e.g., the receiver of the pedicle screw <NUM> in <FIG>, also referred to as the rod channel <NUM> in <FIG>).

In particular implementations, the instrument <NUM> includes a sensor <NUM> configured to detect a load exerted by the rod reducer <NUM> on the spinal rod during seating of the spinal rod in the pedicle screw receiver. In particular examples, the sensor <NUM> includes one or more of: a strain gauge, a pressure-sensitive film, or a capacitive sensor. In various implementations, the sensor <NUM> is configured to sense a load applied via the rod reducer <NUM>, e.g., on the spinal rod. In certain examples, the sensor <NUM> is configured to indicate a pressure and/or torque applied by the rod reducer <NUM>, e.g., on the spinal rod.

In certain implementations, the sensor <NUM> is configured to determine data relating to at least one of: a bone anchor (e.g., anchor <NUM> in <FIG> and/or pedicle screw <NUM> in <FIG> and <FIG>), a spinal rod (e.g., rod <NUM> in <FIG> and/or spinal rod <NUM> in <FIG> and <FIG>), or the reducer <NUM>. In certain examples, the sensor <NUM> provides load data including a tensile load between the rod and the bone anchor when the rod is at least partially seated within the bone anchor. In additional examples, the sensor <NUM> provides load data including torsional force data.

In particular implementations, the sensor <NUM> is located between the proximal end <NUM> and the distal end <NUM> of the rod reducer <NUM>. For example, as illustrated in <FIG>, the reducer <NUM> includes a multi-section shaft <NUM>, including a first section <NUM> and a second section <NUM>, and the sensor <NUM> is mounted axially between the sections <NUM>, <NUM>. In additional examples, such as illustrated in <FIG>, the sensor <NUM> is coupled to the proximal end <NUM> of the rod reducer <NUM>, e.g., on an end of the rod reducer <NUM>.

In particular implementations, a housing <NUM> is coupled to the reducer <NUM>, e.g., at the proximal end <NUM> of the reducer <NUM>. In certain cases, the housing <NUM> includes electronics <NUM> as described herein. In additional implementations, the electronics <NUM> are configured to communicate (e.g., wirelessly and/or hard-wired connection) with a remote spinal fixation management system. In particular cases, the electronics <NUM> include at least one portion of a reduction feedback system <NUM>.

The sensor <NUM> is coupled with the reduction feedback system <NUM> that is configured to: a) receive load data indicating the load exerted by the rod reducer <NUM> on the spinal rod from the sensor; and b) provide an indicator of the load data such that the indicator is detectable by an operator of the instrument <NUM>. As described herein and indicated in phantom in <FIG>, the reduction feedback system <NUM> can be at least partially disposed in the housing <NUM> mounted to the proximal end <NUM> of the reducer <NUM>. In additional implementations, the reduction feedback system <NUM> is at least partially located in a centralized spinal fixation management system, described further herein.

In certain cases, the housing <NUM> is modular and/or disposable. That is, in certain cases, the housing <NUM> substantially contains the reduction feedback system <NUM> and is able to be selectively coupled and/or decoupled with the proximal end <NUM> of the reducer (e.g., with selective couplers such as male/female threading, snap-fit connectors, pressure or force-fit connectors, adhesive(s), etc.). In certain of these cases, the reduction feedback system <NUM> is disposable, that is, intended for one-time use during a spinal fixation procedure. In these examples, the reduction feedback system <NUM> can include onboard electronics that are intended for limited usage, e.g., sensor(s) <NUM>, power, and signal conditioning electronics such as an interface circuit to process and output a signal. In certain cases, the interface circuit includes a signal processor such as a digital signal processor (DSP), a logic engine to filter/condition the signal, and a controller to control onboard functions such as displays and transmission of signals to external components such as an external receiver. In particular examples, the housing <NUM> is selectively coupled to an existing nut on the proximal end <NUM> of the reducer <NUM>. In additional examples, the housing <NUM> is selectively coupled to the central lumen <NUM> or another portion of the body of the reducer <NUM>.

In certain examples, as illustrated in <FIG>, the sensor <NUM> is located within the housing <NUM> with at least a portion of the reduction feedback system <NUM>. In these implementations, the sensor <NUM> can be directly coupled with the reduction feedback system <NUM>, or at least the portion of the reduction feedback system <NUM> that is present in the housing <NUM>. In particular cases, the electronics <NUM> are powered by an onboard power source <NUM> at the housing <NUM> (e.g., one or more batteries, charging devices and/or hard-wired power sources).

A schematic depiction of the reduction feedback system <NUM>, including data flows related to components that interact with the system <NUM>, is illustrated in <FIG>. As described herein, the reduction feedback system <NUM> can function as an onboard (e.g., on instrument <NUM>) system and/or a physically separate system (e.g., coupled via a wireless and/or hard wired connection). In certain cases, as described herein, the reduction feedback system <NUM> is hosted, or otherwise executed as part of a spinal fixation system <NUM>, for example, as described in <CIT> (Systems and Methods for Spinal Surgical Procedures).

In particular implementations, the reduction feedback system <NUM> includes a controller <NUM> (e.g., one or more microcontrollers), that includes at least one processor (PU) <NUM> (such as one or more microprocessors) and is coupled with or contains a memory <NUM> (e.g., including one or more storage components such as memory chips and/or chipsets). The memory <NUM> stores instructions (e.g., reduction feedback (RF) instructions <NUM>) which when executed by the PU(s) <NUM> cause the PU <NUM> to: i) compare the load data obtained from the sensor <NUM> with a load threshold for the reducer <NUM>; and ii) provide an indicator that the load data satisfies or does not satisfy the load threshold for the reducer <NUM>. In particular cases, the load threshold includes a load range for the reducer <NUM> that is indicative of a desired loading of the anchor (e.g., anchor <NUM>, <FIG>, or pedicle screw <NUM>, <FIG>, <FIG>). In various implementations, the load threshold includes a range with an upper and lower bound, which can account for some variation in measurement based on a known measurement margin of error, e.g., of the sensor <NUM>. In additional implementations, the load threshold includes a load value that accounts for a known measurement error, e.g., by one, two, or three percent. In certain implementations, the load threshold is based at least in part on a model that correlates clinical data representing patient- specific bone quality with screw pullout. This clinical data can be engrained in a model stored in the reduction feedback instructions <NUM>, and can be updatable, e.g., as further data becomes available.

In particular implementations, the load data at least partially represents an amount of torque applied to a lock screw during tightening of the lock screw within the pedicle screw receiver (<FIG>) and a compressive force applied to the reducer <NUM>. In certain of these cases, e.g., where the load data does not satisfy the load threshold, the indicator can include an indicator of an amount that the torque applied to the spinal rod should be modified to satisfy the load threshold for the reducer <NUM>.

In particular implementations, the load threshold(s) defines a maximum acceptable load exerted by the reducer <NUM> on the spinal rod <NUM> (<FIG>) during seating of the spinal rod in the receiver of the pedicle screw <NUM> (<FIG>), also referred to as the rod channel <NUM> (<FIG>). In certain cases, the maximum acceptable load is one of: a) approximately <NUM> kilograms to approximately <NUM> kilograms (approximately <NUM> pounds to approximately <NUM> pounds), b) approximately <NUM> kilograms to approximately <NUM> kilograms (approximately <NUM> pounds to approximately <NUM> pounds), or c) approximately <NUM> kilograms to approximately <NUM> kilograms (approximately <NUM> pounds to approximately <NUM> pounds). In certain cases, the maximum acceptable load ranges (a)-(c) are combinable, e.g., approximately <NUM> kilograms to approximately <NUM> kilograms (<NUM> pounds to approximately <NUM> pounds), approximately <NUM> kilograms to approximately <NUM> kilograms (approximately <NUM> pounds to approximately <NUM> pounds), etc..

With continuing reference to <FIG>, an example depiction of a reduction feedback system <NUM> for managing a set of rod reducers 302a, 302b, 302c is illustrated. In these cases, the reduction feedback system <NUM> can be part of a spinal fixation system <NUM> that is configured to manage reducers <NUM> in a multi-level reduction procedure, e.g., where two or more vertebral adjustments are made along a patient's spine. In various implementations, a set of rod reducers <NUM> are engaged with the spinal rod, and the reduction feedback system <NUM> is communicatively coupled to each of the rod reduction instruments (e.g., wirelessly or via hard-wired means) and is configured to receive load data indicating a load exerted by each rod reducer <NUM> on the spinal rod. This depiction includes a few rod reducers 302a, 302b, 302c for simplicity of illustration, but it is understood that the set of rod reducers can include up to twenty (<NUM>) total rod reducers, arranged in subsets of ten (<NUM>) on each side of the patient's spine. <FIG> illustrates an example implementation depicting six reducers 302a-f arranged on one side of a patient's spine, which during an alignment procedure, would correspond with six additional reducers <NUM> (not shown) on the opposite side of the patient's spine (for a total of twelve (<NUM>) reducers <NUM>).

In particular implementations, the reduction feedback system <NUM> is coupled with sensors 308a, 308b, 308c, etc., either directly (such as via a wireless connection or hard-wired connection), or via the onboard reduction feedback system <NUM> at each of the reducers 302a, 302b, 302c, etc. In certain cases, the reducers <NUM> (including sensors <NUM>) are configured to communicate with the reduction feedback system <NUM> via a communications device, e.g., in electronics <NUM> and/or at spinal fixation system <NUM> (<FIG>). The communications device(s) can include one or more transmitters and/or receivers (e.g., wireless and/or hard-wired transmitters/receivers). In various implementations, the communication devices are configured for a plurality of communication protocols, e.g., wireless protocols such as WiFi, Bluetooth, BLE, Zigbee, etc., as well as radio communication and intercom communications, and/or a hardwired connection (e.g., fiber optic connection).

In any case, the reduction feedback system <NUM> (and particularly, PU(s) <NUM>) is configured to compare the load data received from one or more sensors <NUM> with corresponding load thresholds for those sensors <NUM> in order to determine whether one or more reducers <NUM> is appropriately loaded (e.g., over or under loaded). <FIG> illustrates an example data structure of the RF instructions <NUM> for comparing load data <NUM> with a set of thresholds <NUM> in order to determine: a) whether a particular reducer <NUM> is under or over loaded, and b) a reduction order for adjusting the load on a plurality of reducers <NUM>. Based on the load data <NUM>, the RF instructions <NUM> provide reduction (sequencing) instructions <NUM>, such as an identifier of one or more reducers <NUM> and an amount of load adjustment. In certain cases, the reduction instructions <NUM> include reduction sequencing instructions, such as where a plurality of load data <NUM> are obtained as part of a multi-level reduction procedure.

With reference to <FIG>, in various implementations, the reduction feedback system <NUM> is configured to compare load data <NUM> from each of a plurality of sensors <NUM> and provide reduction instructions <NUM>, which can include an indicator of relative loading between at least two of the reducers <NUM>. For example, the indicator of relative loading can indicate whether a given rod reducer (e.g., reducer 302b) is more loaded, less loaded or equally loaded relative to any one of or all of the additional rod reducers (e.g., reducers 302a, 302c) in the set. In various implementations, load data <NUM> is continuously, or periodically, updated during the alignment procedure, such that new load data <NUM> is processed by the reduction feedback system <NUM> for an extended period during the procedure. In particular cases, load data <NUM> is updated every time a change in load at one of the sensors <NUM> is detected, e.g., at every adjustment by the surgeon. In these cases, the reduction instructions <NUM> are continuously updated to reflect the relative load on each reducer <NUM> in the set. In example implementations, the indicator of relative loading always includes an indicator of a least loaded rod reducer <NUM> in the set of reducers, such that the system <NUM> is configured to update the indicator of relative loading over time as load data for at least one of the reducers <NUM> in the set is updated.

As illustrated in <FIG>, the reduction instructions <NUM> can include an indicator of reduction order (or sequencing) for the set of reducers 302a, 302b, 302c, etc. based on the received load data <NUM>. For example, the indicator of reduction order can include reduction instructions <NUM> for multi-step reduction of the set of reducers <NUM>. In particular, <FIG> illustrates an example implementation where the system <NUM>: i) compares the load data <NUM> from two or more reduction instruments (e.g., reducers <NUM>) with a set of thresholds <NUM>, and ii) provides an indicator prioritizing modified loading (e.g., increased or decreased loading) of a particular reduction instrument (e.g., reducer 302b) over at least one additional reduction instrument (e.g., reducer 302a) based on whether the load data <NUM> from the two or more reduction instruments 302a, 302b, satisfies the set of load thresholds. In some cases, the thresholds <NUM> include absolute loading thresholds (e.g., Absolute Loading Thresholds <NUM>, <NUM>, <NUM>) for each of the reducers <NUM>. These absolute loading thresholds can represent a minimum and/or maximum acceptable load value for the load data <NUM> (e.g., as detected by sensor(s) <NUM>). In certain cases, absolute loading thresholds vary based on at least one of: a) location of a given rod reduction instrument (e.g., reducer <NUM>) along the patient's spine, b) the patient's anatomy (e.g., curvature of the spine), or c) the patient's bone quality. For example, the RF instructions <NUM> can be adjusted or otherwise tailored according to patient-specific inputs <NUM>, which can include characteristics of the patient (e.g., physiological and/or anatomical characteristics such as spacing between vertebrae, angulation of one or more sections of the patient's spine, etc.), as well as the patient's bone quality (e.g., on a mechanical bone quality scale such as a T-score (comparing relative health to a standard), or a quality indicator derived from a bone scan such as a CT scan or MRI). For example, absolute loading thresholds can be adjusted based on the patient's bone quality (e.g., lower maximum absolute load threshold for lower bone quality), and/or the angulation of adjacent vertebrae in which the reducers <NUM> are operating (e.g., higher minimum absolute load threshold for higher angulation value). Additionally, the RF instructions <NUM> can be adjusted based on the location of a given reducer <NUM> along the spine, e.g., with distinct absolute loading thresholds at L2 versus L4.

Even further, the load thresholds <NUM> can include relative loading thresholds (e.g., Relative Load Threshold <NUM>, Relative Load Threshold <NUM>) for each of the two or more rod reduction instruments (e.g., reducers 302a, 302b, 302c, etc.). In these cases, the relative loading thresholds can define a maximum allowable difference in loading between any two reducers <NUM>, and/or between any two adjacent reducers (e.g., between reducers 302a and 302b, or reducers 302d and 302e, <FIG>). These relative loading thresholds can be used to determine a reduction order, e.g., to prioritize loading a particular reducer 302a over another reducer 302c. In the example shown in <FIG>, load data <NUM> is processed using absolute load thresholds prior to relative load thresholds, but this order can be reversed in various implementations. In additional implementations, loading thresholds and relative loads can be used to construct a reduction order, e.g., for instructing a user such as a surgeon or other medical professional. In some cases, the load data <NUM> for reducer(s) <NUM> is analyzed based on one or more of: i) a threshold for a given reducer <NUM> or an aggregate threshold for a group of reducers <NUM>, to avoid exceeding a threshold for reducer(s) <NUM>; ii) relative loading between reducers <NUM>, to avoid a loading difference between any two or more reducers <NUM> exceeding a difference threshold; iii) an upper and/or lower reduction bound during manipulation of a reducer <NUM>, or iv) to comply with a reduction order prescribed by pre-operation planning. In certain cases, after comparing the load data <NUM> for two or more reducers 302a, 302b, 302c, etc., the system <NUM> provides at least one load adjustment (e.g., Load Adjustment <NUM>, Load Adjustment <NUM>, etc.), which is placed in an ordered listing for use as reduction (sequencing) instructions <NUM>. For example, reduction (sequencing) instructions <NUM> can include Load Adjustment <NUM> (e.g., adjust torque on reducer 302b with clockwise quarter turn or X lbs of pressure increase), followed by Load Adjustment <NUM> (e.g., after Load Adjustment <NUM>: adjust torque on reducer 302a with counter-clockwise half turn or Y lbs of pressure decrease).

In various implementations, due to the interrelated nature of the loading across different reduction instruments (e.g., reducers 302a, 302b, etc.), reduction sequencing instructions <NUM> can include a multi-reducer sequence that in certain cases involves adjusting the load on a given reducer <NUM> more than once in a complete sequence. For example, the reduction sequencing instructions <NUM> can include instructions to first adjust the load on a first reducer 302a by an amount that does not fully seat the rod into the anchor receiver, then adjust the load on a second reducer 302b, and subsequently further adjust the load on the first reducer <NUM> by an amount that fully seats the rod into the anchor receiver.

In particular implementations, e.g., as illustrated in <FIG>, the spinal fixation system <NUM> can further include an interface <NUM> that enables interaction between the reduction feedback system <NUM> and the surgeon, medical professional(s) and/or other operators in the spinal fixation procedure room. In some cases, the spinal fixation system <NUM> communicates with the reducer(s) <NUM> via a communications device <NUM> such as the wireless and/or hard wired communication devices described herein. The interface(s) <NUM> can include any conventional visual, tactile and/or auditory interface that can enable communication of reduction feedback information to the surgeon, medical professional and/or operator during the spinal fixation procedure. In certain cases, the interface(s) <NUM> include a graphical user interface (GUI), which can include a liquid crystal display (LCD), one or more touch screens, virtual medical assistant systems (e.g., voice- based command system), etc. In particular cases, as illustrated in <FIG>, the interface(s) <NUM> can include a visual indication system <NUM> and/ a tactile indication system <NUM> for providing an indicator of the load data <NUM> (<FIG>) detected by sensors <NUM> at the reducer(s) <NUM>. That is, in certain implementations, at least a portion of the visual indication system <NUM> and/or tactile indication system <NUM> is located at the reducer <NUM> (e.g., at each reducer, coupled with housing <NUM>). In additional implementations, a portion of the visual indication system <NUM> and/or tactile indication system <NUM> can be located at a centralized interface, e.g., interface <NUM> at the spinal fixation system <NUM>.

In certain implementations, the tactile indication system <NUM> includes at least one vibro-tactile actuator, which can be configured to convey to the surgeon (or other medical professional or operator) that a reducer <NUM> requires further loading and/or is approaching an over-loaded condition. For example, the tactile indication system <NUM> can be configured to trigger a vibrational cue (e.g., by vibrating the housing <NUM>) when the loading for a given reducer <NUM> is approaching a maximum absolute loading threshold. In some cases, the tactile indication system <NUM> can be integrated in housing <NUM> or otherwise connected with the housing <NUM> to initiate a vibrational response to the load data from a corresponding sensor <NUM> approaching and/or exceeding a maximum absolute loading threshold. In additional cases, the tactile indication system <NUM> is configured to provide distinct vibrational cues of the loading of a reducer, e.g., a first set of vibrational cues indicating under-loading, and a second set of vibrational cues indicating over-loading or approaching a loading limit.

<FIG> shows an example of a proximal end <NUM> of a reducer <NUM> (e.g., proximal end of housing <NUM>) that includes a visual indication system <NUM> having a set of lights <NUM> configured to be illuminated in at least two distinct patterns to indicate distinctions in the load data for the reducer <NUM>. This example shows lights <NUM> of differing colors, but any progressive lighting arrangement can be used to provide the distinct patterns. For example, an annular arrangement of lights <NUM> as illustrated in <FIG> can be configured to provide distinctions in color, e.g., green indicating desired loading, yellow approaching over-loading, red indicating over-loading. In some cases, this annular arrangement of lights <NUM> has a same or similar color, but can be illuminated in at least two distinct patterns (to indicate over/under loading). An annular lighted arrangement is only one of the various possible arrangements in keeping with the implementations herein, and as such, linear light arrays, light bars, distinctions in light intensity, etc., can be used to visually indicate loading for a given reducer <NUM>.

<FIG> illustrates another example of a visual indication system <NUM> (e.g., via interface <NUM>), including for example, a reduction display <NUM> that includes a bar graph showing load levels (e.g., on a scale of zero to twenty) across a set of ten (<NUM>) distinct reducers <NUM>. In this example, the bar graph can be dynamically updated as changes in load data are detected for one or more reducers <NUM>, such that the viewer (e.g., surgeon, medical professional or other operator) can see which reducers <NUM> are least loaded, or otherwise can withstand increased loading, and which reducer(s) <NUM> are approaching an upper limit for loading. In certain of these cases, the reduction display <NUM> can utilize distinctions in color (not shown) to indicate sequencing or otherwise supplement the indication of the least loaded reducer <NUM>, e.g., the first reducer <NUM> that should undergo an increase in loading.

Returning to <FIG>, in various additional implementations (illustrated in phantom as optional), the reduction feedback system <NUM> is further coupled with one or more additional fixation instrument(s) <NUM>, which can include one or more sensors <NUM>, such as the load sensors described herein. In particular cases, the fixation instrument <NUM> includes a driver configured to tighten a lock screw within a bone anchor receiver (e.g., receiver in bone anchor (e.g., anchor <NUM> in <FIG> and/or pedicle screw <NUM> in <FIG> and <FIG>), and lock a rod (e.g., rod <NUM> in <FIG> and/or spinal rod <NUM> in <FIG> and <FIG>) relative to the bone anchor. Examples of such fixation instruments are provided in US Patent Application Publication No.<CIT> (<CIT>). In further particular cases, the fixation instrument <NUM> includes a guide (also called a "guide tube" in some cases) for defining the trajectory of instruments and/or screws during a spinal surgery. Examples of fixation instruments such as guides and guide tubes are provided in <CIT> (<CIT>).

With reference to additional fixation instruments, <FIG> illustrate side and exploded perspective views, respectively, of an example of a driver <NUM> according to various implementations. In this case, the driver <NUM> has a proximal end <NUM> and a distal end <NUM>, where the distal end <NUM> is configured to engage with and tighten a lock screw. A sensor <NUM> is shown located coaxially with the driver <NUM>, e.g., mounted between or within sections 630A, 630B of the driver shaft <NUM>. In certain cases, the housing for the sensor <NUM> includes one or more mating features <NUM> for coupling with complementary mating features <NUM> in the shaft <NUM>. In certain additional cases, a housing <NUM> mounted to the shaft <NUM>, e.g., near the proximal end <NUM>, includes one or more additional sensors <NUM> and/or electronics <NUM>, power source(s) <NUM>, and/or indication systems <NUM>, <NUM> such as those described with reference to <FIG>. In the example of the driver <NUM> depicted in <FIG>, the sensor(s) <NUM> can be configured to provide torsional force data indicating a torsional force applied on the lock screw during tightening of the lock screw within the receiver, e.g., in the process of locking the rod relative to the bone anchor. In certain cases, the driver (or, driver instrument) <NUM> is configured to be coupled with the rod reducer(s) <NUM> described herein. In particular implementations, the driver <NUM> can be configured to be inserted through the rod reducer <NUM> to deliver and tighten a lock screw within the receiver to lock the rod relative to the bone anchor. According to certain implementations, the sensor(s) <NUM> in driver <NUM> can be configured to provide torsional force data about a torsional force applied by the driver <NUM> on the lock screw. In some examples, the driver <NUM> can be deployed as a "finishing" or "final tightening" driver that is configured to tighten the lock screw in its final or finishing phase. In such cases, the sensor(s) <NUM> in the driver <NUM> can be configured to provide data about the torsional force applied by the driver <NUM> on the lock screw in the final or finishing phase.

In still further implementations, the sensor(s) <NUM> in the fixation instruments <NUM> (e.g., driver <NUM>, rod reducer <NUM> and/or a guide tube) described herein, can be configured to provide data about a load exerted by the fixation instrument <NUM> on the rod during seating of the rod into the receiver of the bone anchor, and/or data about a tensile load between the rod and the bone anchor when the rod is at least partially seated within the bone anchor. In certain implementations, both torque and compression data are recorded by sensor(s) <NUM> on fixation instruments <NUM> and provided to the reduction feedback system <NUM> for analysis and/or action (e.g., to adjust reduction instructions). It is understood that torque and/or compression data detected by sensors <NUM>, e.g., such as in a sensor mounted to the driver <NUM> and/or rod reducer <NUM>, can represent an inferred or correlated indicator of the torque and/or compression applied to a device or component not physically in contact with the sensor <NUM>. For example, the sensor <NUM> on an instrument <NUM> (e.g., driver <NUM>) can be configured to detect torque at the instrument <NUM>, while that torque is being translated to a lock screw in contact with the distal end of the instrument. Similarly, the sensor <NUM> on an instrument <NUM> (e.g., rod reducer <NUM>) can detect compression at the instrument <NUM>, while that compression is being translated to a rod.

In additional implementations, one or more fixation instruments described herein, e.g., rod reducers <NUM>, fixation instrument(s) <NUM>, etc. can be communicatively coupled with a navigation system (e.g., via spinal fixation system <NUM>) that is configured to detect a position of the instrument(s). In one example depiction in <FIG>, a navigation system <NUM> (indicated in phantom as optional) is coupled with the reduction feedback system <NUM> in order to provide navigation information about a position of instruments. For example, the navigation system <NUM> can include an optical tracking system such as a camera or laser-based tracking system, a Global Positioning System (GPS), an inertial measurement unit (IMU), etc. In certain cases, the navigation system <NUM> is configured to determine a distance moved by the instrument when the instrument changes position, which the navigation system <NUM> communicates to the reduction feedback system <NUM>. One or more components of a navigation system <NUM> can be located within or otherwise integrated with a housing, e.g., housing <NUM> (<FIG>), that is mounted to or otherwise coupled with one or more of the reduction instruments. For example, components of a navigation system such as a GPS and/or IMU can be located in a housing <NUM>. In certain examples, the navigation system <NUM> and/or a portion thereof is fixed to a portion of the rod reducer(s) <NUM>, fixation instrument(s) <NUM>, etc., and is physically separated from the housing <NUM>. In some of these cases, e.g., where the housing <NUM> and/or other electronics packages are modular, the navigation system <NUM> can remain independently coupled to the rod reducer <NUM>, fixation instrument <NUM> or other instrument. In additional implementations, the spinal fixation system <NUM> includes or is coupled with a navigation system <NUM> that is external to the housing <NUM> and/or the reduction instruments.

With reference to <FIG> and <FIG>, in additional implementations, the reduction feedback system <NUM> is configured to provide post-operative data and analysis of reduction procedure and/or device usage, e.g., to enhance future procedures and/or diagnose inefficiencies in a past procedure. In certain implementations, the reduction feedback system <NUM> is configured to update the RF instructions <NUM> based on identified inefficiencies or errors in reduction sequencing and/or device usage during a given procedure. In particular implementations, the reduction feedback system <NUM> includes a logic engine configured to modify RF instructions <NUM> iteratively, e.g., on a procedure-by-procedure basis.

As noted herein, the reduction devices, reduction feedback systems and spinal fixation systems disclosed according to various implementations provide numerous benefits relative to conventional spinal fixation devices and systems. For example, the disclosed devices, systems, feedback systems, and methods (not claimed) can enhance efficacy of spinal fixation procedures, as well as mitigate operator (e.g., surgeon) error in performing such procedures. Various disclosed implementations can improve patient outcomes when compared with conventional spinal fixation procedures. Additionally, the disclosed implementations can provide real-time and/or post- operative feedback on reduction procedures, enhancing both current procedural outcomes as well as future surgical outcomes. In certain implementations, the reduction feedback system can provide information to an operator regarding desired reduction ordering in a multi-level reduction procedure, thereby mitigating or avoiding overloading of instruments at any given time during the procedure.

The functionality described herein, or portions thereof, and its various modifications (hereinafter "the functions") can be implemented, at least in part, via a computer program product, e.g., a computer program tangibly embodied in an information carrier, such as one or more non-transitory machine-readable media, for execution by, or to control the operation of, one or more data processing apparatus, e.g., a programmable processor, a computer, multiple computers, and/or programmable logic components.

Actions associated with implementing all or part of the functions can be performed by one or more programmable processors executing one or more computer programs to perform the functions of the calibration process. All or part of the functions can be implemented as, special purpose logic circuitry, e.g., an FPGA and/or an ASIC (application-specific integrated circuit). Components of a computer include a processor for executing instructions and one or more memory devices for storing instructions and data.

In various implementations, components described as being "coupled" to one another can be joined along one or more interfaces. In some implementations, these interfaces can include junctions between distinct components, and in other cases, these interfaces can include a solidly and/or integrally formed interconnection. That is, in some cases, components that are "coupled" to one another can be simultaneously formed to define a single continuous member. However, in other implementations, these coupled components can be formed as separate members and be subsequently joined through known processes (e.g., soldering, fastening, ultrasonic welding, bonding). In various implementations, electronic components described as being "coupled" can be linked via conventional hard-wired and/or wireless means such that these electronic components can communicate data with one another. Additionally, sub-components within a given component can be considered to be linked via conventional pathways, which may not necessarily be illustrated.

While inventive features described herein have been described in terms of preferred embodiments for achieving the objectives, it will be appreciated by those skilled in the art that variations may be accomplished in view of these teachings without deviating from the scope of the invention. Also, while this invention has been described according to a preferred use in spinal applications, it will be appreciated that it may be applied to various other uses desiring surgical fixation, for example, the fixation of long bones.

Claim 1:
A rod reduction instrument (<NUM>) adapted for use with a spinal fixation system, the rod reduction instrument (<NUM>) comprising:
- a rod reducer (<NUM>) having a proximal end (<NUM>) and a distal end (<NUM>), wherein the distal end (<NUM>) of the rod reducer (<NUM>) is configured to engage a spinal rod (<NUM>) for seating the spinal rod (<NUM>) into a pedicle screw receiver;
- a sensor (<NUM>) configured to detect a load exerted by the rod reducer (<NUM>) on the spinal rod (<NUM>) during seating of the spinal rod (<NUM>) in the pedicle screw receiver; and
- a reduction feedback system (<NUM>) coupled with the sensor (<NUM>), the reduction feedback system (<NUM>) configured to:
- receive load data indicating the load exerted by the rod reducer (<NUM>) on the spinal rod (<NUM>) from the sensor (<NUM>); and
- provide an indicator of the load data that is detectable by an operator of the rod reduction instrument (<NUM>) characterized in that
- the reduction feedback system (<NUM>) comprises a processor (<NUM>) and memory (<NUM>), the memory (<NUM>) storing instructions which when executed, cause the processor (<NUM>) to: compare the load data with a load threshold for the rod reducer (<NUM>); and provide an indicator that the load data satisfies or does not satisfy the load threshold for the rod reducer (<NUM>).