Patent ID: 12226128

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the implementations illustrated in the drawings and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure may be intended. Any alterations and further modifications to the described devices, instruments, methods, and any further application of the principles of the present disclosure are fully contemplated as would normally occur to one skilled in the art to which the disclosure relates. In particular, it may be fully contemplated that the features, components, and/or steps described with reference to one or more implementations may be combined with the features, components, and/or steps described with reference to other implementations of the present disclosure. For simplicity, in some instances the same reference numbers are used throughout the drawings to refer to the same or like parts.

Embodiments generally relate to spinal surgery. More particularly, embodiments relate to systems, methods, and devices for securing a spinal rod with a polyaxial clamp assembly.

The polyaxial clamp assembly can be utilized for open and percutaneous approaches to the posterior spine. The polyaxial clamp assembly locks or restricts polyaxial motion (e.g., movement in multiple directions) of a screw (e.g., a pedicle screw) before locking or restricting movement of the spinal rod. This allows corrective forces to transfer to vertebra for axial derotation, parallel compression, parallel distraction, and/or reduction.

Although polyaxial motion of the screw may be locked or prevented, the polyaxial screw is free to translate and rotate about the spinal rod. Additionally, the polyaxial motion may also be left unrestricted during correction to allow the same functionality as a typical polyaxial screw. Once correction is achieved, tightening a locking cap into a head of the polyaxial screw secures the spinal rod to prevent movement of the spinal rod.

Particular embodiments of the present disclosure allow restriction of polyaxial motion of a screw head of a pedicle screw, creating a rigid connection between a vertebral body and a surgeon's hand that applies corrective forces. This allows for improved control over motion of the vertebral bodies to aid in correction maneuvers while maintaining the ability of the polyaxial screw to accept a spinal rod at multiple angles. Existing monoaxial screws provide this rigidity but do not accept the spinal rod at multiple angles, requiring accurate contouring of the spinal rod to match a location and orientation of the screw head. Uniplanar screws allow rigidity in one plane but do not accept spinal rods at various angles.

In certain embodiments, spinal rods of varying diameter may be captured and secured by allowing an inner set screw to thread into contact with the spinal rod at varying heights. In particular embodiments, threading an internal locking cap into the spinal rod may compress against a saddle or collet to restrict motion.

FIG.1Aillustrates a polyaxial clamp assembly (“clamp assembly”)100in accordance with particular embodiments of the present disclosure. The clamp assembly100may include a tulip102. The tulip102may be a rigid member that resembles a bullet with a hollow interior. The tulip102may include an opening104situated between portions106aand106b. A curved portion108may be disposed between the portions106aand106b, as shown. The curved portion108may be curved to correspond with a shape of a spinal rod118. In certain embodiments, the opening104may extend from the curved portion108to distal ends110aand110bof the portions106aand106b, as shown. Inner surfaces112aand112bof the portions106aand106bmay be threaded as shown onFIG.1B. An outer screw114may be disposed within the opening104, as shown. An inner screw116may be disposed concentrically within the outer screw114. The spinal rod118may extend through the opening104, and a screw such as a pedicle screw115may extend through a passage117(shown onFIG.1B) of the curved portion108. In certain embodiments, the spinal rod118may extend in a direction that is orthogonal to a longitudinal axis of the concentrically positioned outer screw114and inner screw116.

FIG.1Billustrates a cross section of the clamp assembly100in accordance with particular embodiments of the present disclosure. The cross-section is taken along the dashed line as shown onFIG.1A. As shown onFIG.1B, an inner surface114aand an outer surface114bof the outer screw114may be threaded. Outer threads116aof inner screw116may align or mate with the inner surface114a. The inner surfaces112aand112bof the portions106aand106bmay align or mate with the outer surface114b, as shown.

A saddle120may be movably disposed within the opening104, as shown. The saddle120may be an elongated rigid member with a shape similar to the tulip102. The saddle120includes an opening120aat a first end122aand an opening120bpositioned opposite to the opening120aat a second end122b, as shown. The opening120amay be similar to the opening104. The saddle120may include a ridge103that projects into a recess105extending along an inner surface107of the tulip102, thereby preventing movement of the saddle120beyond the recess105, as shown.

A screw head119of the pedicle screw115may be disposed within the passage117and the opening120b. The opening120bmay include surface topography124such as curvature that corresponds with the shape of the screw head119to facilitate securing of the pedicle screw115within the clamp assembly100, as shown.

The clamp assembly100is permitted to rotate about the screw head119via a spherical joint formed between the saddle120and screw head119, as shown. A retaining member126is retained in a groove117aof the passage117and retains the screw head119within the clamp assembly100to prevent disassembly, as shown. The retaining member126may be a clip or a ring that extends along a circumference of the screw head119.

In particular embodiments, the spinal rod118is accepted by the tulip102and then captured by the outer screw114which is threaded into the tulip102(and may be pre-assembled with the inner screw116). Further tightening of the outer screw114compresses the saddle120against the pedicle screw115, and compresses against the retaining member126retained within the tulip102. This compression restricts the motion of the pedicle screw115within the clamp assembly100while allowing translation and rotation of the clamp assembly100about the spinal rod118.

Tightening the inner screw116secures the spinal rod118to the saddle120, fully restricting all degrees of freedom to form a rigid construct, as shown. The inner screw116can be rotated to compress the spinal rod118within the opening120a. The spinal rod118may be squeezed and secured between an inner surface121of the opening120aand a distal end116aof the inner screw116, as shown.

FIG.2Aillustrates a clamp assembly200, in accordance with particular embodiments of the present disclosure. The clamp assembly200may be similar to the clamp assembly100. As shown, the tulip102may include grooves202extending along a perimeter of the opening104, as shown. In particular embodiments, the tulip102may be movably disposed within a pusher instrument203including a sleeve204and arms208, as shown. Rails206may extend from the sleeve204into the grooves202thereby holding and retaining the tulip102within the sleeve204.

FIG.2Billustrates a cross section of the clamp assembly200in accordance with particular embodiments of the present disclosure. The cross-section is taken along the dashed line as shown onFIG.2A. As shown onFIG.2B, the arms208may extend from the sleeve204into slots210of the tulip102. A locking cap212may be disposed within the opening104as shown. The locking cap212may be similar to the inner screw116and/or the outer screw114. The saddle120may include indentations214to receive distal ends of the arms208.

Translation of the pusher instrument203compresses the saddle120against the screw head119which locks or prevents polyaxial motion thereof. As shown, the screw head119is compressed between the retaining member126and the saddle120. The spinal rod118may then be inserted into the opening104before being captured and secured by the locking cap212, or it may have already been captured by the locking cap212before the polyaxial motion was locked. Tightening the locking cap212secures the spinal rod118to the saddle120, fully restricting all degrees of freedom to form a rigid construct. The pusher instrument203may then be removed.

FIG.3illustrates a cross-section of a clamp assembly300in accordance with particular embodiments of the present disclosure. As shown, the clamp assembly300includes a first locking cap302and a second locking cap304. Both locking caps302and304may be threaded into internal threads of the tulip306. The locking caps302and304can be rotated to compress a saddle308against a screw310and the retaining member126to lock polyaxial motion, as shown. Then, the spinal rod118may be placed to extend between the locking caps302and304, as shown. Not introducing the first locking cap302allows the spinal rod118to compress against the saddle308, providing equivalent function as a polyaxial screw. The saddle308and first locking cap302may be combined into a single component to simplify the design and reduce profile.

FIG.4illustrates a cross-section of a clamp assembly400in accordance with particular embodiments of the present disclosure. As shown, the clamp assembly400includes cam components402housed in the tulip404are rotated by a pusher instrument component203to compress the saddle408against the screw410and the retaining member126to lock the polyaxial motion. The spinal rod118may then be introduced and locked against the saddle408by the threaded locking cap412. Compression of the spinal rod118against the saddle408maintains the polyaxial lock (i.e., restricted movement) after the pusher instrument203has been removed.

FIGS.5A and5Billustrate cross-sections of a clamp assembly500in accordance with particular embodiments of the present disclosure. As shown onFIG.5A, the saddle502is in an initial positioned within the tulip504. The saddle502may be rotated and translates down to compress against a screw (e.g., screw410shown onFIG.4) and a retaining member (e.g., the retaining member126shown onFIG.4).

FIG.5Billustrates the saddle502in an actuated or downward position, as shown. Actuation may occur via an instrument (not shown) which pushes the saddle502down, then rotates it under a shelf506in the tulip504. A spinal rod (e.g., the spinal rod118) may then be introduced and locked against the saddle502by a locking cap (e.g., the locking cap302). Compression of the spinal rod118against the saddle502maintains the polyaxial lock after the instrument has been removed.

FIG.6illustrates a tulip600in accordance with particular embodiments of the present disclosure. As shown, the tulip600may be collapsible. A lower portion602of the tulip600may be separated from an upper portion604. The lower portion602and the upper portion604may include or form spherical or conical tapered cavities606and608, respectively, as shown. The shapes of the cavities606and608may correspond with a shape of the screw head119which may be spherical or include a portion that is spherical. The cavities606and608allow the screw head119of the screw115to rotate. Translation of the portions602and604toward each other, as indicated by the arrows, compresses the cavities606and608around the screw head119of the screw115to restrict polyaxial motion. This translation may be accomplished by an external threaded nut (not shown). The spinal rod118may then be introduced and locked against a saddle (e.g., the saddle502as shown onFIGS.5A and5B) by a locking cap610, as shown.

FIG.7illustrates a saddle700in accordance with particular embodiments of the present disclosure. The saddle700may be a spherical collet or a threaded saddle. As shown, the saddle700may be housed in a cavity702of a tulip704and mates with a threaded screw head706. The threads708between the saddle700and threaded screw head706are tapered so that when the saddle700is rotated with respect to the threaded screw head706, the saddle700expands into the cavity702, restricting polyaxial motion. A screw710may be driven into bone to rotate it with respect to the saddle700and the threaded screw head706. The spinal rod118(e.g., shown onFIG.6) may then be introduced and tightened with the locking cap610(e.g., shown onFIG.6) to compress against the saddle700or a saddle component. The retaining member126(shown onFIG.1B) may be disposed in the cavity702to allow assembly. In certain embodiments, the saddle700may include a driving feature712to drive the saddle700into position. Also, the screw710may include a driving feature714, as shown.

FIG.8Aillustrates a clamp assembly800in accordance with particular embodiments of the present disclosure. The clamp assembly800may be similar to the clamp assembly200. As shown, the pusher instrument203compresses against the saddle120to restrict the polyaxial motion. In this embodiment the pusher instrument203is inserted through a locking cap802to engage the saddle120instead of through a side of the tulip102.

FIG.8Billustrates a top view of the locking cap802in accordance with particular embodiments of the present disclosure. As shown, the locking cap802includes a through-hole804.

FIG.8Cillustrates a top view of the tulip102in accordance with particular embodiments of the present disclosure. As shown onFIG.8C, the tulip102includes notches806that allow the pusher instrument203(e.g., shown onFIGS.8A and8D) to be maneuvered around threads808(e.g., shown onFIG.8D) of the tulip102to drive the saddle120into a locking position.

FIG.8Dillustrates a perspective view of the tulip102in accordance with particular embodiments of the present disclosure. As shown, the pusher instrument203may be maneuvered through the notches806to drive the saddle120into a locking position.

FIG.9Aillustrates prongs900utilized to position the saddle120in accordance with particular embodiments of the present disclosure. As shown, the prongs900may contact the saddle120at corners901(e.g., four corners) of the saddle120.

FIG.9Billustrates prongs900contacting the saddle120in accordance with particular embodiments of the present disclosure. A locking cap (e.g., the locking cap302) may be disposed above the saddle120as indicated by arrow902. As shown, the prongs900may reach around the locking cap as indicated by arrows904.

FIG.9Cillustrates a space906between the prongs900in accordance with particular embodiments of the present disclosure. The space906may be utilized to receive the spinal rod118. As shown, the prongs900may reach around the spinal rod118and apply force to the corners901.

FIG.10Aillustrates a clamp assembly1000in accordance with particular embodiments of the present disclosure. As shown, an external locking ring1002threads onto external threads1004of the tulip1006. Tightening the external locking ring1002compresses against extensions1008of the saddle1010extending through walls1012of the tulip1006to lock the polyaxial motion of the pedicle screw115. The extensions1008may extend from an external shelf1013of the tulip1006, as shown. Tightening a set screw1014to internal threads1016of the tulip1006locks the spinal rod118to the saddle1010. The external locking ring1002may be removed or left on the tulip1006. The external locking ring1002may be an implantable ring or a component of an instrument used to lock motion of the spinal rod118and/or the pedicle screw115.

FIG.10Billustrates a top view of the extensions1008in accordance with particular embodiments of the present disclosure. As shown, the extensions1008protrude from the walls1012.

FIG.11Aillustrates a clamp assembly1100in accordance with particular embodiments of the present disclosure. As shown, a set screw1102is tightened to compress against the screw head119of the screw115, restricting polyaxial motion. The set screw1102may not be axially aligned with the screw head119to allow it to compress the spherical screw head119, or it may be offset from the screw head119with an internal wedge which compresses into the screw head119to restrict motion.

FIG.11Billustrates a clamp assembly1200in accordance with particular embodiments of the present disclosure. As shown, the set screw1102may contact and drive a wedge1202into the screw head119of the screw115thereby locking the screw115in place.

FIG.12illustrates a saddle1300in accordance with particular embodiments of the present disclosure. As shown, a threaded tulip1302may be tightened to compress against the spherical head (e.g., screw head119of the screw115shown onFIG.11A), restricting polyaxial motion. The threaded tulip1302may be combined with the saddle1300, as shown. The saddle1300may be loaded from a top of the threaded tulip1302and may be rotated 90° to lock the saddle1300in place.

FIG.13illustrates a tulip1400in accordance with particular embodiments of the present disclosure. As shown, the tulip1300accepts the screw head119in a spherical collet1402. Translation of an external tapered ring1404closes the spherical collet1402of the screw head119about the screw head119, restricting polyaxial motion. The external tapered ring1404may be translated by an instrument (not shown) and held in the locked position by a bump feature (not shown) on the screw head119or may be threaded onto the screw head119.

FIG.14Aillustrates a perspective view of clamp assembly1500in accordance with particular embodiments of the present disclosure. The clamp assembly1500may be similar to the clamp assembly100, as shown onFIG.1for example.

FIG.14Billustrates a cross-section of the clamp assembly1500in accordance with particular embodiments of the present disclosure. The clamp assembly1500may include a threaded locking cap1502. The retaining member126is retained in the tulip102and retains the screw head119within the tulip102to prevent disassembly. The spinal rod118is accepted by the tulip102and then captured and secured by the threaded locking cap1502which is threaded into the tulip102, into contact with the spinal rod118. Further tightening of the locking cap1502compresses the spinal rod118into a rod slot1504of the saddle120, which compresses the saddle120against the screw head119and compresses against the retaining member126retained within the tulip102. This compression restricts the motion of the spinal rod118and the screw head119.

FIG.14Cillustrates a top view of the saddle120disposed within the tulip102in accordance with particular embodiments of the present disclosure. The clamp assembly1500may be assembled by inserting the saddle120into the top of the tulip102, inserting a screw head119into the bottom of the tulip102, inserting the retaining member126, then rotating the saddle120so that an elliptical profile of the saddle120aligns with an elliptical bore of the tulip102and prevents the saddle120from rotating out of alignment. Slots1506cut into the saddle120interface with an assembly tool (not shown) to facilitate this rotation.

FIG.14Dillustrates a top view of the threaded locking cap1502and the saddle120disposed within the tulip102in accordance with particular embodiments of the present disclosure. As shown, the threaded locking cap1502may be tightened to lock the saddle120into place.

FIG.14Eillustrates a partial cross-section of the tulip102and the threaded locking cap1502in accordance with particular embodiments of the present disclosure. As shown, threads1508and1510include a slight positive angle on upper surfaces1512and1514. The upper surfaces1512and1514are contacted and loaded when tightened. The lower surfaces1516and1518of the threads1508and1510are angled at a greater positive angle than the upper surfaces1512and1514, so that if the screw head119were deformed outwards, the lower surfaces1516and1518should contact and resist the splaying deformation.

FIG.15Aillustrates a perspective view of a clamp assembly1600in accordance with particular embodiments of the present disclosure. The clamp assembly1600may be similar to the clamp assembly1500, as shown onFIG.14Afor example. As shown, a bottom portion or start1602of the thread1510ain a threaded locking cap1502aand a top portion or start1604of the thread1508aof the tulip1601are timed with corresponding markings and/or cutouts1606and1608, respectively, in the threaded locking cap1502aand/or the tulip1601. When the markings and/or cutouts1606and1608are aligned, the start1602is close to engaging the thread1508aof the tulip1601. This allows the user to quickly and repeatably engage the thread1510awith the thread1508a.

Two sets of instrument interface features on the tulip1601allow attachment of instruments for reduction, derotation, and placement. Four obround reduction pockets1610or two chevron slots1612accept mating obround or “chevron” shaped tabs on instruments (not shown).

FIG.15Billustrates a top view of tulip1601of the clamp assembly1600in accordance with particular embodiments of the present disclosure. As shown, the tulip1601includes two large radii1616, which transition into four angled flat surfaces1620, which transition into four radii1622, which transitions into a flat surface1624(also shown onFIG.15C) perpendicular to a rod slot1626. The spinal rod118may extend through the rod slot1626, as shown.

FIG.15Cillustrates a side view of the clamp assembly1600in accordance with particular embodiments of the present disclosure. The lower shape1627of the tulip1601includes of an outer diameter1628which tapers to the lower surface1629by a radius1630, as shown.

FIG.16illustrates a partial cross-section of the tulip1601and the threaded locking cap1502ain accordance with particular embodiments of the present disclosure. As shown, thread1510aincludes radii1700on inside corners1702of the thread1510ato increase strength. Corresponding chamfers or radii1704have been added to thread1508afor clearance with the radii1700.

FIG.17illustrates a clamp assembly1800in accordance with particular embodiments of the present disclosure. As shown, the tulip1801may include a cylindrical pocket1802which interfaces with a corresponding cylindrical feature in a mating instrument (not shown). The tulip1801may include perpendicular flat faces1804and1806cut into a circular diameter1808. A locking cap1808may be threaded into the tulip1801, as shown.

FIG.18illustrates a partial cross-section of the tulip1801and the locking cap1808in accordance with particular embodiments of the present disclosure. As shown, threads1810of the locking cap1808and threads1812of the tulip1801may be square threads. As shown, top surfaces1900of threads1810and top surfaces1902of the threads1812and bottom surfaces1904(of the threads1810) and bottom surfaces1906(of the thread1812) are perpendicular to major axis1908and minor diameters1910of the threads1810and1812, as shown.

FIG.19illustrates a clamp assembly2000in accordance with particular embodiments of the present disclosure. As shown, a locking cap2002is inserted into or housed within the tulip102. An instrument (not shown) is used to engage the drive feature (shown onFIGS.21A and21B) of the upper portion2004of the locking cap2002and apply a torque until the point of failure.

A section of the locking cap2002is designed to fail at a torque equivalent to the torque required to lock the clamp assembly2000. This can be done by adding an external or internal groove (see grooves2004and2006onFIGS.20A and20B, respectively) to reduce the cross section of where the break-off feature meets the desired final implant position within the tulip102, or by pockets or thru holes2008(seeFIG.20C) cut to reduce the cross-section.

FIG.20Aillustrates a cross-section of a locking cap2002ain accordance with particular embodiments of the present disclosure. As shown, the locking cap2002amay include an external groove2004to reduce the cross section of where the break-off feature meets the desired final implant position within the tulip102.

FIG.20Billustrates a cross-section of a locking cap2002bin accordance with particular embodiments of the present disclosure. As shown, the locking cap2002bmay include an internal groove2006to reduce the cross section of where the break-off feature meets the desired final implant position within the tulip102.

FIG.20Cillustrates a cross-section of a locking cap2002cin accordance with particular embodiments of the present disclosure. As shown, the locking cap2002cmay include thru holes2008to reduce the cross section of where the break-off feature meets the desired final implant position within the tulip102.

FIG.21Aillustrates a drive feature2100positioned on a break off portion2101that is an external hex drive in accordance with particular embodiments of the present disclosure.FIG.21Billustrates a drive feature2102positioned on a break off portion2101that is an internal hex drive in accordance with particular embodiments of the present disclosure. In some embodiments, the drive features2100and2102may be a hexalobe (torx).

FIG.22illustrates a secondary drive feature2200in accordance with particular embodiments of the present disclosure. The secondary drive feature2200may be left in the tulip102to allow for removal or re-tightening.

FIG.23Aillustrates a break off feature2300in accordance with particular embodiments of the present disclosure. The break off feature2300may be a set screw, as shown.

FIG.23Billustrates a break off feature2302in accordance with particular embodiments of the present disclosure. The break off feature2302may be a quarter turn locking cap, as shown.

FIG.23Cillustrates a break off feature2304in accordance with particular embodiments of the present disclosure. The break off feature2304may be a threaded locking cap, as shown.

An advantage of this disclosure is that a consistent torque can be applied upon tightening that does not rely on a torque limiting or torque measuring device which may drift out of calibration and provide an inconsistent torque and is costly and burdensome to recalibrate.

It is believed that the operation and construction of the present disclosure will be apparent from the foregoing description. While the apparatus and methods shown or described above have been characterized as being preferred, various changes and modifications may be made therein without departing from the spirit and scope of the disclosure as defined in the following claims.