Rod reducer

A rod reducer includes a shaft, a sleeve assembly defining a bore dimensioned to receive the shaft therethrough, a housing defining a bore dimensioned to receive the shaft, arm members operatively associated with the housing, and an anvil operatively coupled with the shaft. The sleeve assembly includes a locking tab. The housing includes a groove configured to selectively receive the locking tab of the sleeve assembly. The housing includes a locking ledge portion in registration with the groove. The anvil is transitionable between a proximal position, in which, the arm members are spaced apart, and a distal position, in which, the arm members are in an approximated position. The sleeve assembly is rotatable between an engaged state in which, the locking ledge portion inhibits relative axial displacement of the sleeve assembly with the housing, and a disengaged state in which, the sleeve assembly is axially movable relative to the housing.

BACKGROUND

Technical Field

The present disclosure relates to a spinal deformity correction device and, more particularly, to a manually operated rod reducer for reducing a spinal rod into a bone screw in a controlled and measured manner.

Description of Related Art

The spine is made up of a superposition of vertebrae that are normally aligned along a vertebral axis, extending from the lumbar vertebrae to the cervical vertebrae. There are many known spinal conditions, e.g., scoliosis, that require the imposition and/or maintenance of corrective forces on the spine in order to return the spine to its normal condition. When an individual's spine presents abnormal curvature, the vertebrae are inclined relative to one another and relative to the vertebral axis. The lateral edges of the vertebrae situated on one side are thus closer to one another and form a concave curve, while the lateral edges on the other side appear spaced apart from one another and form a convex curve. In order to straighten the spinal column, the lateral edges of the vertebrae on the concave side are spaced apart from one another and are taken relative to one another to a distance that is substantially equivalent to the distance between the lateral edges on the other side.

In order to keep the vertebrae in that position relative to one another, numerous alignment devices have been developed for use in spinal fixation. One type of spinal construct may include, for example, one or more spinal rods that can be placed parallel to the spine with fixation devices (such as hooks, screws, or plates) interconnected between the spinal rods at selected portions of the spine.

The process of properly inserting the spinal rod into the receiving slot of one or more bone screws, followed by securing the connecting rod therein, often requires the clinician to use a number of instruments and expend a great deal of time and effort. The repeated process of inserting and securing the spinal rod into one or more bone screws secured to adjacent vertebrae can be difficult, tiresome, and time consuming. Therefore, a continuing need exits for a device that can safely and efficiently reduce the spinal rod into the screw housing and lock the spinal rod in place.

SUMMARY

The present disclosure describes a device for reducing a spinal rod into a screw housing that demonstrates a practical approach to meeting the performance requirements and overcoming usability challenges associated with reducing a spinal rod. In accordance with an embodiment of the present disclosure, there is provided a rod reducer including a shaft, a sleeve assembly defining a first bore dimensioned to receive the shaft therethrough, a housing defining a second bore dimensioned to receive the shaft therethrough, arm members operatively associated with the housing, and an anvil operatively coupled with the shaft. The sleeve assembly includes a locking tab. The housing includes a groove configured to selectively receive the locking tab of the sleeve assembly. The housing includes a locking ledge portion in registration with the groove. The anvil is transitionable between a proximal position, in which, the arm members are spaced apart, and a distal position, in which, the arm members are in an approximated position. The sleeve assembly is rotatable about the shaft between an engaged state in which, the locking tab of the sleeve assembly engages the groove of the housing such that the locking ledge portion inhibits relative axial displacement of the sleeve assembly with the housing, and a disengaged state in which, the locking tab of the sleeve assembly is offset from the groove such that the sleeve assembly is axially movable relative to the housing.

In an embodiment, the sleeve assembly may include a sleeve defining a cavity and a nut disposed in the sleeve. The nut may include the locking tab.

In another embodiment, the locking tab of the nut may extend distally out of the sleeve.

In a further embodiment, the nut may have a cross-section complementary to a cross-section of the cavity of the sleeve for concomitant rotation with the sleeve.

In still another embodiment, the nut may include a pair of transverse wings defining a slot.

In yet another embodiment, the sleeve assembly may further include a biasing member disposed within the slot of the pair of transverse wings. The biasing member may be configured to bias the sleeve proximally.

In yet another embodiment, the nut may include threads configured to threadably engage the shaft.

In still another embodiment, the groove of the housing may include an arcuate profile.

In still another embodiment, the sleeve assembly may be rotated about 90 degrees about the shaft during transition between the engaged and disengaged states.

In still another embodiment, the shaft may be rotatably supported with the anvil such that rotation of the shaft causes axial displacement of the anvil along the arm members.

In still another embodiment, the second bore of the housing may be configured to slidably receive the shaft therethrough.

In still yet another embodiment, the sleeve may include a gripping surface including ridges.

In still yet another embodiment, the anvil may include a saddle including an arcuate profile configured to engage a spinal rod.

In an embodiment, the anvil may define opposing cavities dimensioned to receive the respective arm members therethrough.

In accordance with another embodiment of the present disclosure, there is provided a rod reducer including a shaft, a housing defining a first bore configured to slidably receive the shaft therethrough, a sleeve assembly defining a second bore configured to threadably receive the shaft therethrough, arm members pivotably coupled with the housing, and an anvil operatively coupled with the shaft. The anvil is movable along the arm members, which, in turn, transitions the arm members between an approximated position and a spaced apart position. The sleeve assembly is rotatable about the shaft. The sleeve assembly is transitionable between an engaged state in which the sleeve assembly is engaged with the housing, and a disengaged state in which the sleeve assembly is axially movable relative to the housing.

In an embodiment, the shaft may be non-rotatably slidable through the first bore when the sleeve assembly is in the disengaged state.

DETAILED DESCRIPTION OF EMBODIMENTS

Particular embodiments of the present disclosure will be described herein with reference to the accompanying drawings. As shown in the drawings and as described throughout the following description, and as is traditional when referring to relative positioning on an object, the terms “proximal” and “trailing” may be employed interchangeably, and should be understood as referring to the portion of a structure that is closer to a clinician during use. The terms “distal” and “leading” may also be employed interchangeably, and should be understood as referring to the portion of a structure that is farther from the clinician during use. In addition, the term “cephalad” is used in this application to indicate a direction towards a patient's head, whereas the term “caudad” indicates a direction towards the patient's feet. Further still, the term “medial” indicates a direction towards the middle of the body of the patient, while the term “lateral” indicates a direction towards a side of the body of the patient (i.e., away from the middle of the body of the patient). The term “posterior” indicates a direction towards the patient's back, and the term “anterior” indicates a direction towards the patient's front. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

With reference toFIGS. 1-3, a rod reducer in accordance with an embodiment of the present disclosure is generally shown as a rod reducer100. The rod reducer100may be utilized to reduce a spinal rod200(FIG. 18) into a slot332(FIG. 18) of a screw housing330of a bone screw300. In particular, the rod reducer100provides a sleeve assembly30that enables quick release or engagement of the rod reducer100with the bone screw300, which, in turn, reduces the time required for surgery and reduces the fatigue experienced by the clinician when compared with manually rotating a shaft20in order to disengage or engage the rod reducers100with the respective bone screws300.

With reference toFIGS. 3 and 4, the rod reducer100includes a shaft20, the sleeve assembly30including a sleeve35and a nut40, a housing50, an anvil60, and arm members70. The shaft20includes an elongate body22having threads22aconfigured to threadably engage the nut40, as will be discussed below. The elongate body22includes a distal portion24defining an annular groove24aconfigured to rotatably engage anvil60, and a proximal portion26defining a cavity26ahaving, e.g., a hex, key feature for non-slip engagement with a driver or other instrument (not shown) to drive the shaft20. It is contemplated that cavity26amay have any suitable configuration such as, e.g., slotted, square, star fitting, or a Phillips head, for engagement with the driver.

With reference toFIGS. 4-9, the sleeve assembly30includes a sleeve35defining a cavity32, and a nut40configured to be operatively received in the sleeve35. The sleeve35may include opposing gripping surfaces39having, e.g., ridges, configured to enhance gripping by the clinician. The sleeve35further includes opposing sides36extending between the opposing gripping surfaces39. The opposing sides36may have, e.g., an arcuate profile. The opposing sides36may define, e.g., respective grooves38, to further enhance gripping by the clinician or a tool. The sleeve35defines bores34dimensioned to receive respective pins90(FIG. 4) extending through the nut40, as will be described below.

With reference now toFIGS. 10-12, the nut40has a shape complementary to a shape of the cavity32(FIG. 7) of the sleeve35in order to provide concomitant rotation with the sleeve35, while enabling axial displacement of the nut40within the sleeve35. The nut40has a proximal portion40aand a distal portion40b. The proximal portion40aincludes opposing anchoring portions41, and the distal portion40bincludes locking tabs47extending distally out of the sleeve35when the nut40is disposed in the sleeve35. The nut40defines a bore46extending between the proximal and distal portions40a,40b. Internal walls defining the bore46include threads46aconfigured to threadably engage the elongate body22(FIG. 4) of the shaft20. In addition, the nut40includes a pair of wings42on respective lateral sides45a,45bof the nut40. Each pair of wings42defines a slot42adimensioned to receive a biasing member80(FIG. 4) such as, e.g., a spring. The opposing anchoring portions41are in communication with the respective slots42a. In addition, each lateral wing42defines a camming slot42bdimensioned to receive the pin90(FIG. 4) therethrough. Under such a configuration, each biasing member80(FIG. 4) is received in a respective slot42adefined by the respective pair of lateral wings42. A first end80aof the biasing member80is supported against the anchoring portion41of the nut40, and a second end80bof the biasing member80is secured with the pin90extending through the camming slots42bof the lateral wings42and the bores34(FIG. 4) of sleeve35. In this manner, the biasing members80provide a proximal biasing force on the respective pins90, which, in turn, provides a proximal biasing force on the sleeve35.

With reference now toFIGS. 13-15, the housing50is coupled with the sleeve assembly30and the arm members70. The sleeve assembly30is rotatably coupled with the housing50in order to selectively detach the sleeve assembly30from the housing50. The housing50defines a bore52dimensioned to slidably receive the shaft20(FIG. 4) therethrough. The housing50defines opposing grooves54a,54babout the bore52. The opposing grooves54a,54bare dimensioned to slidably receive the locking tabs47(FIG. 11) of the nut40of the sleeve assembly30. Each of the opposing grooves54a,54bmay include an arcuate profile to facilitate rotation of the locking tabs47therethrough. In addition, the housing50includes opposing locking ledge portions56a,56bin registration with the respective grooves54a,54b. Under such a configuration, when the locking tabs47of the nut40are in registration with the opposing grooves54a,54bof the housing50, e.g., aligned with an axis “L-L” (FIG. 13), the locking ledge portions56a,56binhibit axial displacement of the sleeve assembly30relative to the housing50. However, when the sleeve assembly30is rotated such that the locking tabs47of the nut40are disengaged from the respective grooves54a,54bof the housing50, e.g., the locking tabs47of the nut40are aligned with an axis “U-U” (FIG. 13) orthogonal to the axis “L-L,” the sleeve assembly30may be detached or spaced apart from the housing50to, e.g., quickly release the arm members70(FIG. 16) from the bone screw300(FIG. 18), as will be discussed hereinbelow. Under such a configuration, the shaft20is non-rotatably slidable through the bore52of the housing50when the sleeve assembly30is disengaged from the housing50. In this manner, the anvil60may be slidably movable along the arm members70without having to manually rotate the shaft20by the clinician.

With reference now toFIGS. 13-16, the housing50is operatively coupled with the arm members70. In particular, the housing50defines pin holes58dimensioned to receive respective pins95(FIG. 4) extending through bores72defined in the respective arm members70. In this manner, each arm member70may be pivotally coupled to the housing50such that the arm members70are movable between approximated and spaced apart positions. However, it is also envisioned that the arm members70and the housing50may be integrally formed as a single construct, in which, the arm members70are radially deflectable to engage with or disengage from the bone screw300(FIG. 18).

With particular reference toFIG. 16, each of the arm members70includes an elongate body70aincluding a proximal portion70band a distal portion70c. As discussed hereinabove, the proximal portion70bdefines the bore72operatively coupled with the housing50, and the distal portion70cincludes an engaging portion74such as, e.g., a hook, configured to engage the bone screw300(FIG. 18). In particular, the arm members70are secured with the housing50such that the arm members70diametrically oppose each other in order to enhance securement with the bone screw300. The elongate body70amay be formed of a material having low friction to facilitate sliding of the anvil60(FIG. 17) therealong.

With reference now toFIG. 17, the anvil60defines a bore64dimensioned to receive the shaft20(FIG. 4), and opposing cavities62a,62babout the bore62. The opposing cavities62a,62bare dimensioned to receive the respective arm members70(FIG. 16) therethrough. Under such a configuration, axial displacement of the anvil60relative to the arm members70transitions the engaging portions74(FIG. 16) of the arm members70between an approximated position, in which, the engaging portions74engage the bone screw300(FIG. 18), and a spaced apart position, in which, the space created between the engaging portions74enables, e.g., disengagement or placement, of the engaging portions74with the bone screw300. In addition, the anvil60further defines pin holes68dimensioned to receive respective pins97(FIG. 4) configured to be received in the annular groove24a(FIG. 4) defined in the distal portion24of the shaft20(FIG. 4). The pins97diametrically oppose each other. Under such a configuration, the pins97disposed in the annular groove24aof the shaft20enable rotation of the shaft20, while inhibiting axial displacement of the shaft20relative to the anvil60.

The anvil60further includes a saddle66configured to reduce the spinal rod200(FIG. 18) into a slot332defined in a screw housing330of the bone screw300(FIG. 18). The saddle66may include an arcuate or convex profile to facilitate reduction of the spinal rod200. The saddle66may be configured to accommodate a range of spinal rod diameters. For example, the saddle66may be adapted to cooperatively engage with a spinal rod120having a diameter ranging from about 3 mm to about 8 mm, while still providing the driving force necessary to secure the spinal rod200into the bone screw300.

In use, with reference toFIGS. 18 and 19, the clinician initially prepares the vertebrae (not shown). The bone screws300(FIG. 18) are positioned at desired locations on the spine in order to provide the desired placement and securement of the spinal rods200. Once the desired number of the bone screws300have been implanted, the clinician aligns and manipulates the spinal rod200such that a portion of the spinal rod200is in proximal relation to the screw housings330of the respective bone screws300. Prior to using the spinal rod200, the clinician may manipulate the spine to a desired curvature. In addition, the spinal rod200may be bent using a bending tool (not shown) as known in the art, to the configuration of the desired spinal curvature such as, e.g., the sagittal curve. Thereafter, the clinician may position the pre-bent spinal rod200relative to the bone screws300.

Next, the clinician positions the rod reducer100into proximity with the respective bone screw300, such that the engaging portions74of the arm members70of rod reducer100is in near abutment to the screw housing330of the bone screws300. Next, the clinician causes the engaging portion74of the arm members70to grasp or otherwise affix to the screw housing330by rotating the shaft20. Manually rotating shaft20such a distance can be cumbersome, tedious, and time consuming. Thus, while the sleeve assembly30may be utilized for the quick release feature, the clinician may also slide the shaft20distally through the housing50to cause the engaging portions74to engage the screw housing330, while the sleeve assembly30is disengaged from the housing50. The shaft20may be threaded into the sleeve assembly30by a pre-determined amount prior to the surgical procedure.

The rod reducer100provides a mechanical advantage to further bend or shape the spinal rod200, while the spinal rod200is securely held by the rod reducer100and the screw housing330of the bone screw300. In this configuration, the clinician may make final adjustments to the spinal rod200. After spinal rod200is properly aligned, the clinician may further reduce spinal rod200to secure the spinal rod200into the screw housing330of the bone screw300. Thereafter, the clinician reduces the spinal rod200into the slot332of the screw housing330. For example, there may be about 15 mm or more of travel required in order to reduce the spinal rod200fully within the saddle332of the screw housing330such that spinal rod200and screw housing can be locked.

With a plurality of rod reducers100mounted to different bone screws300, the clinician is able to gradually reduce the spinal rod200to a plurality of bone screws300by sequentially reducing each rod reducer100fully or partially until all of the rod reducers100have been actuated fully and the spinal rod200is reduced into all of the bone screws300.

Upon final alignment of spinal rod200between the bone screws300, and/or securement of spinal rod200into the screw housing330thereof, the clinician may decouple the rod reducers100from the respective bone screws300by rotating the respective sleeve assemblies30such that the locking tabs47of the nut40are offset from the locking ledge portions56a,56bof the housing50. At this time, the shaft20may be pulled proximally, which, in turn, transitions the arm members70to be spaced apart and enables the clinician to disengage the rod reducer100from the bone screw300. Alternatively, the shaft20may be manually rotated in order to move the shaft20proximally. As the clinician translates anvil60towards the proximal position, the arm members70of the respective rod reducer100may be decoupled from the bone screw300, permitting the clinician to detach the rod reducer100from the respective bone screw300.

It is contemplated that the rod reducer100may be provided in a kit that includes the rod reducer100, the bone screws300, the spinal rods200, and an orthopedic tool (not shown) including, e.g., a tightening or loosening tool, an alignment tube, or a locking device.

While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of presently disclosed embodiments. Thus, the scope of the embodiments should be determined by the claims of the present application and their legal equivalents, rather than by the examples given.