# US 8,540,770 B2 · Adjustable intervertebral implant

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- Number: US 8,540,770 B2
- Document ID: US8540770B2
- Status: Granted
- Kind: B2
- Application number: 13/061,388
- Filed: 2008-09-04
- Published: 2011-09-08
- Granted: 2013-09-24
- Earliest claimed: 2008-09-04
- Assignees: DePuy Synthes Products, Inc.
- Applicants: William N. Woodburn, Sr.; Tom Pepe; William McDonough; Douglas S. Kephart; David E. Evans
- Inventors: William N. Woodburn, Sr.; Tom Pepe; William McDonough; Douglas S. Kephart; David E. Evans
- Web page: https://patentgrep.com/patent/US8540770B2

## CPC

- A61F 2/442: {Intervertebral or spinal discs, e.g. resilient (non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455)}
- A61F 2/44: for the spine, e.g. vertebrae or spinal discs
- A61F 2/4611: {of spinal prostheses}
- A61F 2/30744: {End caps, e.g. for closing an endoprosthetic cavity}
- A61F 2002/2835: {Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material}
- A61F 2002/3008: {radio-opaque, e.g. radio-opaque markers}
- A61F 2002/30133: {kidney-shaped or bean-shaped}
- A61F 2002/30237: {partial tubes}
- A61F 2002/30369: {Limited lateral translation of the protrusion within a larger recess}
- A61F 2002/30383: {made by laterally inserting a protrusion, e.g. a rib into a complementarily-shaped groove}
- A61F 2002/30405: {made by screwing complementary threads machined on the parts themselves}
- A61F 2002/30492: {using a locking pin}
- A61F 2002/30495: {using a locking ring}
- A61F 2002/305: {Snap connection}
- A61F 2002/30507: {using a threaded locking member, e.g. a locking screw or a set screw}
- A61F 2002/30523: {by means of meshing gear teeth}
- A61F 2002/3055: {for adjusting length}
- A61F 2002/30593: {hollow}
- A61F 2002/30594: {slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots}
- A61F 2002/30601: {telescopic}
- A61F 2002/30604: {modular}
- A61F 2002/30616: {Sets comprising a plurality of prosthetic parts of different sizes or orientations}
- A61F 2002/30787: {inclined obliquely with respect to each other}
- A61F 2002/3079: {Stepped or enlarged apertures, e.g. having discrete diameter changes}
- A61F 2002/30841: {Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes}
- A61F 2002/4628: {with linear motion along or rotating motion about an axis transverse to the instrument axis or to the implantation direction, e.g. clamping}
- A61F 2220/0025: Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
- A61F 2220/0033: made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
- A61F 2230/0015: Kidney-shaped, e.g. bean-shaped
- A61F 2230/0069: cylindrical
- A61F 2250/0098: radio-opaque, e.g. radio-opaque markers
- A61F 2310/00017: Iron- or Fe-based alloys, e.g. stainless steel
- A61F 2310/00023: Titanium or titanium-based alloys, e.g. Ti-Ni alloys
- A61F 2310/00179: Ceramics or ceramic-like structures
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)

## Abstract

An adjustable intervertebral implant (100) for implantation into a patient's spine in-between first and second adjacent or neighboring vertebrae. The implant may include one or more of the following features: (i) inner (110) and outer (115) members coupled by a radiographically imageable expansion ring (130), (ii) detachable endplates (120,125) coupled to the implant via a polygonal press-fit coupling interface that accommodate a range of lordotic endplates to be applied to the implant using any surgical approach, (iii) an interference pre-loaded set screw (160) for selectively locking the height of the construct, (iv) a radiographically imageable marker (180) for determining the expansion of the implant, and (v) an asymmetric thread coupling (133,190) between the expansion ring and the inner member.

## Claims

### Claim 1

An adjustable intervertebral implant for implanting between neighboring vertebral bodies to replace all or a significant portion of a damaged vertebra, the adjustable intervertebral implant comprising:
a radiolucent inner member having a longitudinal axis extending between a first end and a second end, an outer surface, a throughslot extending from the second end of the inner member along the longitudinal axis of the inner member, and a first threading on the outer surface of the inner member;
a radiolucent outer member having a longitudinal axis extending between a first end and a second end, and an outer surface, the inner member slidably received within the outer member and being slidably movable along the longitudinal axis of the outer member;
a radiographically visible expansion ring having inner and outer surfaces, the inner surface having a second threading thereon, wherein a width of crests of the first threading is greater than a width of crests of the second threading, the expansion ring being rotatably coupled to the outer member so that rotation of the expansion ring results in engagement of the first and second threadings and slidable translation of the inner member with respect to the outer member, the expansion ring further including a plurality of unthreaded throughslots disposed circumferentially around the expansion ring; and
at least one set screw wherein advancement of one of the at least one set screw within a corresponding one of the plurality of unthreaded throughslots disposed around the expansion ring causes a distal end of said one of the at least one set screw to bear against the outer surface of the inner member and thereby secure the inner member relative to the outer member in a locked position.

### Claim 2

An adjustable intervertebral implant for implanting between adjacent vertebrae bodies to replace all or a significant portion of a damaged vertebra, the adjustable intervertebral implant comprising:
an inner member having a longitudinal axis extending between a first end and a second end, an outer surface, a throughslot extending from the second end of the inner member along the longitudinal axis of the inner member, and a first threading on the outer surface of the inner member;
an outer member having a longitudinal axis extending between a first end and a second end, an internal surface, an outer surface, and a tab protruding from the first end of the outer member along the longitudinal axis of the outer member and terminating in a lip the inner member slidably received within the outer member and being slidably movable along the longitudinal axis of the outer member, the slidable movement guided by interaction of the tab protruding from the outer member with the throughslot formed in the inner member;
an expansion ring having inner and outer surfaces, the inner surface having a second threading thereon, the expansion ring received around the tab protruding from the outer member and below the lip so as to be freely rotatable with respect to the outer member, rotation of the expansion ring resulting in engagement of the first and second threadings and translation of the inner member with respect to the outer member, wherein a width of crests of the first threading is different than a width of crests of the second threading thereby providing an asymmetric thread geometry upon engagement of the first and second threadings, the expansion ring further including a plurality of unthreaded throughslots disposed circumferentially around the expansion ring; and
at least one set screw, each of the at least one set screw having a head and a threaded shaft, wherein advancement of one of the at least one set screw within a corresponding one of the plurality of unthreaded throughslots disposed around the expansion ring causes a distal end of said one of the at least one set screw to bear against the outer surface of the inner member and thereby secure the inner member relative to the outer member in a locked position.

### Claim 3

An adjustable intervertebral implant for implanting between adjacent vertebrae bodies to replace all or a significant portion of a damaged vertebra, the adjustable intervertebral implant comprising:
a radiolucent inner member having a longitudinal axis extending between a first end and a second end, an outer surface, a throughslot extending from the second end of the inner member along the longitudinal axis of the inner member, a first threading on the outer surface of the inner member, and a coupling interface at the first end of the inner member;
a radiolucent outer member having a longitudinal axis extending between a first end and a second end, an internal surface, an outer surface, and a tab protruding from the first end of the outer member along the longitudinal axis of the outer member and terminating in a lip, the inner member slidably received within the outer member and being slidably movable along the longitudinal axis of the outer member, the slidable movement guided by interaction of the tab protruding from the outer member with the throughslot formed in the inner member, the outer member including a coupling interface at the second end of the outer member;
a radiographically visible expansion ring having inner and outer surfaces, the inner surface having a second threading thereon, wherein a width of crests of the first threading is greater than a width of crests of the second threading, the expansion ring received around the tab protruding from the outer member and below the lip so as to be freely rotatable with respect to the outer member, wherein actuation of the expansion ring results in engagement of the first and second threadings and slidable translation of the inner member with respect to the outer member, the expansion ring further including a plurality of unthreaded throughslots disposed circumferentially around the expansion ring, each of the plurality of unthreaded throughslots characterized by a proximal portion and a distal portion, wherein the proximal portion of each of the plurality of unthreaded throughslots is characterized by a diameter larger than a diameter of the distal portion of each of the plurality of unthreaded throughslots; and
a plurality of pre-loaded set screws, each of the plurality of pre-loaded set screws having a head and a threaded shaft, the head of each of the plurality of pre-loaded set screws positioned within the proximal portion of a corresponding one of the plurality of unthreaded throughslots by an interference fit, wherein advancement of any one of the plurality of pre-loaded set screws within a corresponding one of the plurality of unthreaded throughslots disposed around the expansion ring causes a distal end of said any one of the plurality of pre-loaded set screws to bear against the outer surface of the inner member and thereby secure the inner member relative to the outer member in a locked position.

### Claim 4 (depends on 3)

The adjustable intervertebral implant of claim 3, further comprising:
detachable superior and inferior endplates each having a coupling interface for attachment to the coupling interfaces of the first end of the inner member and the second end of the outer member, respectively.

### Claim 5 (depends on 4)

The adjustable intervertebral implant of claim 4, wherein the coupling interfaces are each comprised of a polygonal coupling interface having a shape of a polygon, allowing each endplate to be coupled to the respective inner or outer member at any number of positions that correspond to a number of sides of the polygon.

### Claim 6 (depends on 4)

The adjustable intervertebral implant of claim 4, wherein at least one of the superior or inferior endplates includes a lordotic or kyphotic taper.

### Claim 7 (depends on 3)

The adjustable intervertebral implant of claim 3, further comprising:
a radiographically imageable marker disposed within the inner member.

### Claim 8 (depends on 7)

The adjustable intervertebral implant of claim 7, wherein the radiographically imageable marker is comprised of a pin mounted proximate the second end of the inner member.

### Claim 9 (depends on 8)

The adjustable intervertebral implant of claim 8, wherein the pin includes a pin axis, the pin axis oriented perpendicular to the longitudinal axis of the inner member.

### Claim 10 (depends on 3)

The adjustable intervertebral implant of claim 3, wherein the distal end of at least one of the plurality of pre-loaded set screws engages a planar apex of the first threading of the inner member in the locked position.

### Claim 11 (depends on 3)

The adjustable intervertebral implant of claim 3, wherein the second end of the inner member is positioned proximate the second end of the outer member and the first end of the inner member is positioned proximate the first end of the outer member in a loading position, the second end of the inner member positioned proximate the first end of the outer member in a fully expanded position.

### Claim 12 (depends on 11)

The adjustable intervertebral implant of claim 11, further comprising:
a radiographically imageable pin mounted proximate the second end of the inner member.

### Claim 13 (depends on 3)

The adjustable intervertebral implant of claim 3, wherein the plurality of pre-loaded set screws is comprised of five (5) pre-loaded set screws.

### Claim 14 (depends on 13)

The adjustable intervertebral implant of claim 13, wherein the throughslots are evenly spaced circumferentially around the expansion ring, thereby defining throughslot angles centered on the longitudinal axis.

### Claim 15 (depends on 3)

The adjustable intervertebral implant of claim 3, wherein the outer member includes an instrument engagement feature.

### Claim 16 (depends on 3)

The adjustable intervertebral implant of claim 3, wherein the coupling interfaces of the first end of the inner member and the second end of the outer member have an octagonal shape.