Expandable implant

Abstract

An expandable implant for inserting within a skeletal space is provided, and a method for using the implant to expand the skeletal space. The implant is preferably designed to be inserted into an intervertebral space to replace at least part of an intervertebral disc between adjacent vertebral bodies. The expandable implant contains at least one first expansion compartment and at least one second expansion compartments, which compartments can be inflatable balloons that are inflated by a catheter. Inflating the first expansion compartment expands the implant in a first direction and inflating the second expansion compartment expands the implant in a second direction.

Claims

1. An intervertebral implant expandable in at least a first direction, the implant comprising: a first bone contacting member defining a first bone contacting surface configured to face a first vertebra; a second bone contacting member defining a second bone contacting surface configured to face a second vertebra, the second bone contacting surface spaced from the first bone contacting surface in a second direction that is perpendicular to the first direction, wherein the implant is configured to be inserted into an intervertebral space in a third direction that is perpendicular to the first and second directions; and an expansion compartment positioned between the first and second bone contacting surfaces, wherein the expansion compartment is expandable so as to expand the implant along the first direction, wherein the expansion compartment comprises a coupling element configured to be coupled to a fixing member of one of the first and second bone contacting members, wherein expansion of the implant along the first direction causes the coupling element to detach from the fixing member thereby permitting at least a portion of the first bone contacting member to tilt relative to at least a portion of the second bone contacting member.

2. The intervertebral implant of claim 1, wherein the first bone contacting member comprises a first component and a second component spaced from the first component along the first direction, the second bone contacting member comprises a third component and a fourth component spaced from the third component along the first direction, the at least a portion of the first bone contacting member is one of the first and second components, and the at least a portion of the second bone contacting member is one of the third and fourth components.

3. The intervertebral implant of claim 2, wherein a select one of the first, second, third, and fourth components is restricted from tilting relative to another of the first, second, third, and fourth components when the coupling element is coupled to the fixing member, and the select one of the first, second, third, and fourth components is permitted to tilt relative to the another of the first, second, third, and fourth component when the coupling element is detached from the fixing member.

4. The intervertebral implant of claim 3, wherein the expansion compartment is positioned between the third and fourth components in the first direction, the expansion compartment is elongate along the third direction, and the third and fourth components and the expansion compartment are collectively configured such that expansion of the expansion compartment increases a distance between the third and fourth components in the first direction so as to expand the implant in the first direction.

5. The intervertebral implant of claim 4, further comprising a second expansion compartment that is positioned between the third and fourth components and is adjacent the first expansion compartment in the first direction.

6. The intervertebral implant of claim 5, wherein the fixing member is a first protrusion defined by the third component, the first protrusion is elongate in the first direction, the coupling element is a first hook, the first hook is received over the first protrusion prior to expansion of the implant in the first direction, the fourth component defines a second protrusion elongate in the first direction and facing the first protrusion, the second expansion compartment comprises a second hook that is received over the second protrusion prior to expansion of the implant in the first direction, and the first and second hooks are configured to slide off the first and second protrusions, respectively, responsive to the distance between the third and fourth components increasing in the first direction.

7. The intervertebral implant of claim 6, further comprising: a third expansion compartment positioned between the first and third components, wherein the third expansion compartment is expandable so as increase a distance between the first and third components in the second direction; and a fourth expansion compartment positioned between the second and fourth components, wherein the fourth expansion compartment is expandable so as to increase a distance between the second and fourth components in the second direction.

8. The intervertebral implant of claim 7, wherein: the first component comprises a third protrusion elongate in the second direction; the second component comprises a fourth protrusion elongate in the second direction; the third expansion compartment comprises a third hook received over the third protrusion; and the fourth expansion compartment comprises a fourth hook received over the fourth protrusion, the third hook is configured to slide off the third protrusion responsive to the distance between the first and third components increasing in the second direction, and the fourth hook is configured to slide off the fourth protrusion responsive to the distance between the second and fourth components increasing in the second direction.

9. The intervertebral implant of claim 8, wherein each of the first, second, third, and fourth components is restricted from tilting relative to each of the other of the first, second, third, and fourth components when the first, second, third, and fourth hooks are received over the first, second, third, and fourth protrusions, respectively, and each of the first, second, third, and fourth components is permitted to tilt relative to each of the other of the first, second, third, and fourth components after the first, second, third, and fourth hooks slide off the first, second, third, and fourth protrusions, respectively.

10. The intervertebral implant of claim 7, further comprising: a first expandable connection coupled to the first and second components; and a second expandable connection coupled to the third and fourth components, wherein each of the first and second expandable connections is expandable in the first direction.

11. The intervertebral implant of claim 10, further comprising: a third expandable connection coupled to the first and third components; and a fourth expandable connection coupled to the second and fourth components, wherein each of the third and fourth expandable connections is expandable in the second direction.

12. The intervertebral implant of claim 11, wherein each of the first, second, third, and fourth expandable connections comprises wire netting that includes a plurality of individual link members.

13. The intervertebral implant of claim 7, wherein each of the first, second, third, and fourth expansion compartments comprises a balloon having an opening configured to receive filling material for causing expansion of the balloon.

14. The intervertebral implant of claim 7, wherein the first and second components collectively define the first bone contacting surface, and the third and fourth components collectively define the second bone contacting surface.

15. An intervertebral implant expandable in at least a first direction, the implant comprising: a first bone contacting member defining a first bone contacting surface configured to face a first vertebra; a second bone contacting member defining a second bone contacting surface configured to face a second vertebra, the second bone contacting surface spaced from the first bone contacting surface in a second direction that is perpendicular to the first direction, wherein the implant is configured to be inserted into an intervertebral space in a third direction that is perpendicular to the first and second directions; and a first expansion compartment positioned between the first and second bone contacting surfaces, the first expansion compartment comprising a coupling element configured to be coupled to a fixing member of one of the first and second bone contacting members, wherein the first expansion compartment is expandable so as to expand the implant along the first direction causing the coupling element to detach from the fixing member, thereby detaching the first expansion compartment from the one of the first and second bone contacting members, a second expansion compartment positioned between the first and second bone contacting members, wherein the second expansion compartment is expandable so as to move the first and second bone contacting surfaces away from one another in the second direction.

16. The intervertebral implant of claim 15, wherein the second expansion compartment is positioned relative to the first and second bone contacting members so as to cause tilting of one of the first and second bone contacting surfaces relative to the other of the first and second bone contacting surfaces responsive to expansion of the second expansion compartment.

17. The intervertebral implant of claim 16, wherein another of the first and second bone contacting members comprises a second fixing member, the second expansion compartment further comprises a second coupling element configured to be coupled to the second fixing member, and expansion of the implant along the second direction causes the second coupling element to detach from the second fixing member, thereby detaching the second expansion compartment from the other of the first and second bone contacting members.

18. The intervertebral implant of claim 17, wherein the one of the first and second bone contacting members is permitted to tilt relative to the other of the first and second bone contacting members when the second coupling element is detached from the second fixing member.

19. The intervertebral implant of claim 18, further comprising a third expansion compartment positioned between the first and second bone contacting members, the third expansion compartment spaced from the second expansion compartment in the first direction, wherein the third expansion compartment is expandable so as to move the first and second bone contacting surfaces away from one another in the second direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a top perspective view of an implant according to the present invention in an insertion configuration.

(2) FIG. 2 is a cross-sectional view of the implant shown in FIG. 1 taken through the plane A-A.

(3) FIG. 3 is a cross-sectional view of an implant shown in FIG. 1 positioned in an intervertebral space.

(4) FIG. 4 is a cross-sectional view of the implant shown in FIG. 1 which has been expanded in a first direction.

(5) FIG. 5 is a cross-sectional view of the implant shown in FIG. 1 which has been expanded in a first direction and in a second direction.

(6) FIG. 6 is a rear perspective view of the implant shown in FIG. 1 in an insertion configuration.

(7) FIG. 7 is a cross-sectional view of the implant shown in FIG. 1 taken through the plane B-B.

(8) FIG. 8 is a rear perspective view of the implant shown in FIG. 1 which has been expanded in a first direction.

(9) FIG. 9 is a rear perspective view of the implant shown in FIG. 1 which has been expanded in a first direction and in a second direction.

(10) FIG. 10 is a cross-section view of an alternative implant according to the present invention in an insertion configuration.

DETAILED DESCRIPTION

(11) Specific embodiments of the present invention are now described by way of example only with reference to the drawings. It will be recognised that features specified in one embodiment of the invention may be combined with other specified features to provide further embodiments.

(12) With reference to FIGS. 1, 2 and 3, an implant (10) according to one embodiment of the present invention is shown in an insertion configuration. The implant has a front end (80) and a rear end (90). The implant (10) has a first contacting member (12) consisting of two contacting components (16, 18) linked by a first expandable connection (24) and a second contacting member (14) consisting of two contacting components (20, 22) linked by a second expandable connection (26). The first contacting member (12) and the second contacting member (14) are linked by a third expandable connection (28, 30).

(13) The implant (10) has a first cavity (40) between one contacting component (18) of the first contacting member (10) and one contacting component (22) of the second contacting member (14) in which is housed a second expansion compartment (36). The implant (10) also has a second cavity (42) between the other contacting component (16) of the first contacting member (12) and the other contacting component (20) of the second contacting member (14) in which is housed a further second expansion compartment (38). The two second expansion compartments are in the form of longitudinally shaped balloons.

(14) The implant (10) has a third cavity (44) between the contacting components (20, 22) of the second contacting member (14) in which are housed two first expansion compartments (32, 34). The first expansion compartments are in the form of longitudinally shaped balloons.

(15) The contacting components (16, 18) of the first contacting member (12) each have a plurality of teeth (50) on their outermost surface. The contacting components (20, 22) of the second contacting member (14) each have a plurality of teeth (52) on their outermost surface.

(16) The two first expansion compartments (32, 34) may be filled with filling material via a catheter (not shown) attached to an entry portion (54, 56) of each of the first expansion compartments.

(17) The two second expansion compartments (36, 38) may be filled with filling material via a catheter (not shown) attached to an entry portion (58, 60) of each of the second expansion compartments.

(18) The first contacting member (12) comprises a groove (61, 62) on the outer edge of each of the contacting components (16, 18) to which an implant holding and insertion instrument (not shown) can be attached to the implant (10).

(19) The first contacting member (12) comprises recesses (64, 66) and the second contacting member comprises recesses (68, 70) to which an implant holding and insertion instrument (not shown) can be attached to the implant (10).

(20) While in the insertion configuration, the implant (10) may be inserted into a skeletal space. FIGS. 2 and 3 show the implant (10) inserted into an intervertebral space (200) between a first vertebra (100) and a second vertebra (102). The implant (10) may be inserted into the intervertebral space (200) through a lateral incision in a patient. An implant holding and insertion instrument (not shown) engages with an arrangement of grooves (61, 62) and recesses (64, 66, 68, 70) on the implant (10) and the implant holding and insertion instrument is used to insert the implant into the intervertebral space (200). The implant holding and insertion instrument (not shown) is then detached from the implant (10). In the insertion configuration, the implant has a dimension d.sub.1 in a first direction and a dimension t.sub.1 in a second direction.

(21) When inserted into the intervertebral space, the plurality of teeth (50) on the outermost surface of the first contacting member (12) engage with a surface (104) of the first vertebra (100) and the plurality of teeth (52) on the outermost surface of the second contacting member (14) engage with a surface (106) of the second vertebra (102).

(22) With reference to FIGS. 4 and 5, which show features corresponding to those in FIGS. 2 and 3, the sequential expansion of the embodiment described in FIGS. 1 to 3, is effected by first simultaneously expanding the first expansion compartments (32, 34) with a filler material via catheters (not shown). Expansion of the first expansion compartments (32, 34) causes the first expandable connection (24) and the second expandable connection (26) to expand and the contacting components (16, 18) in the first contacting member (12) to move apart such that the implant has a dimension d.sub.2 in the first direction. The third expandable connection (28, 30) does not expand and the dimension t.sub.1 in the second direction remains unchanged. In this embodiment, the implant (10) is inserted such that the first direction corresponds to the a-p direction.

(23) Subsequent to expansion of the first expansion compartments (32, 34), expansion in second direction, which corresponds to the c-c direction, is effected by simultaneously expanding the second expansion compartments (36, 38). Expansion of the second expansion compartments (36, 38) causes the third expandable connection (28, 30) to expand and the first and second contacting members (12, 14) to move apart such that the implant has a dimension t.sub.2 in the second direction. The dimension d.sub.2 in the second direction remains unchanged.

(24) With reference to FIGS. 6 and 7 the first expansion compartments (32, 34) each comprise a hook portion (132, 134) that cooperates with first fixings (122, 124) positioned at the rear end (90) of the implant (10) to attach the first expansion compartments (32, 34) to the implant (10). The second expansion compartments (36, 38) each comprise a hook portion (130,136) that cooperates with second fixings (120, 126) positioned at the rear end (90) of the implant (10) to attach the second expansion compartments (36, 38) to the implant (10).

(25) With reference to FIGS. 8 and 9, as the first expansion compartments (32, 34) expand, the contacting components (16, 18) of the first contacting member move apart, the contacting components (20, 22) of the second contacting member move apart and the first and second expandable connections (24, 26) expand. This expansion allows the hook portions (132, 134) of first expansion compartments (32, 34) to slide off the first fixings (122, 124) and hence the first expansion compartments (32, 34) detach from the implant (10).

(26) As the second expansion compartments (36, 38) expand, the contacting components (16, 18) of the first contacting member move apart from the contacting components (20, 22) of the second contacting member and the third expandable connection (30) expands. This expansion allows the hook portions (130, 136) of the second expansion compartments (36, 38) to slide off the second fixings (120, 126) and hence the second expansion compartments (36, 38) detach from the implant (10).

(27) With reference to FIG. 9, following detachment of the first and second expansion compartments (32, 34, 36, 38), the contacting components (16, 18) of the first contacting member (12) are able to tilt relative to each other and relative to the respective contacting components (20, 22) of the second contacting member (14).

(28) With reference to FIG. 10, an implant (310) according to an alternative embodiment of the present invention is shown in an insertion configuration. The implant (310) has a first contacting member (312) consisting of two contacting components (316, 318) linked by a first expandable connection (324) and a second contacting member (314) consisting of two contacting components (320, 322) linked by a second expandable connection (326). The first contacting member (312) and the second contacting member (314) are linked by a third expandable connection (328, 330).

(29) The implant (310) has a first cavity (340) between one contacting component (318) of the first contacting member (310) and one contacting component (322) of the second contacting member (314) in which is housed a second expansion compartment (336). The implant (310) also has a second cavity (342) between the other contacting component (316) of the first contacting member (310) and the other contacting component (320) of the second contacting member (314) in which is housed a further second expansion compartment (338).

(30) The implant (310) has a third cavity (344) between the contacting components (320, 322) of the second contacting member (314) in which are housed two first expansion compartments (332, 334).

(31) Expansion of the first expansion compartments (332, 334) causes the contacting components (320, 322) of the second contacting member (314) to move apart and the first and second expandable connections (324, 326) to expand. In this way, the implant (310) increases in dimension in a first direction (x). Due to the angled shape of the cavities (340, 342) between the first and second expansion members (312,314), expansion of the second expansion compartments (336, 338) causes the first contacting member (312) to move apart from the second contacting member (314), causing the third expandable connection (328, 330) to expand and, in addition, causes contacting components (316, 318) of the first contacting member (312) to move further apart and the first expandable connection (324) to further expand.

EXAMPLES

(32) Embodiments of the present invention are now described, by way of illustration only, in the following examples. It will be understood that these examples are not limiting and that variations and modifications may be made within the spirit and scope of the invention as set out above and as defined in the following claims.

Example 1

(33) Four separate catheter balloons (OPN NC High Pressure PTCA Balloons from Sis Medical, having a highest rated burst pressure of 35 bar) were inserted into a bottom end of a cannulated implant holding and insertion instrument and pushed through the instrument such that part of the tubes connected to the catheter balloons were retained within the instrument but catheter balloons protruded from the top end of the instrument. The four balloons were subsequently inserted into an implant as shown in FIG. 1. The implant was mounted on the implant holding and insertion instrument using a pair of protruding blade springs which engaged with grooves on either side of the implant and retained the implant in a compressed, insertion configuration.

(34) A lateral incision was made in a cadaveric specimen and residual intervertebral disc material was removed between the L3 and L4 vertebrae. The implant was inserted in a compressed, insertion configuration into the L3 to L4 intervertebral disc space.

(35) A first inflation device (High Pressure Inflation Device from Sis Medical) was attached to the two balloons arranged to cause anterior-posterior expansion and a second inflation device of the same type was attached to the two balloons arranged to cause cranio-caudal expansion. The implant holding and insertion instrument was detached from the implant.

(36) Water at a pressure of between 24 and 30 bar was introduced into the two balloons arranged to cause antero-posterior expansion using the first inflation device. The anterior-posterior dimension of the implant increased without causing any increase in the cranio-caudal dimension of the implant.

(37) Subsequently, water at a pressure of between 24 and 30 bar was introduced into the two balloons arranged to cause cranio-caudal expansion using the second inflation device. The cranio-caudal dimension of the implant increased without causing any increase in the anterior-posterior dimension of the implant. A biomechanical study of the resulting expanded implant showed that it stabilized the L3 and L4 vertebrae.

Example 2

(38) Four separate catheter balloons (OPN NC High Pressure PTCA Balloons from Sis Medical, having a highest rated burst pressure of 35 bar) were inserted into a bottom end of a cannulated implant holding and insertion instrument and pushed through the instrument such that part of the tubes connected to the catheter balloons were retained within the instrument but catheter balloons protruded from the top end of the instrument. The four balloons were subsequently inserted into an implant as shown in FIG. 1. The implant was mounted on the implant holding and insertion instrument using a pair of protruding blade springs which engaged with grooves on either side of the implant and retained the implant in a compressed, insertion configuration.

(39) A lateral incision was made in a cadaveric specimen and residual intervertebral disc material was removed between the L3 and L4 vertebrae. The implant was inserted in a compressed, insertion configuration into the L3 to L4 intervertebral disc space.

(40) A first inflation device (High Pressure Inflation Device from Sis Medical) was attached to the two balloons arranged to cause anterior-posterior expansion and a second inflation device of the same type was attached to the two balloons arranged to cause cranio-caudal expansion. The implant holding and insertion instrument was detached from the implant.

(41) Polymethyl methacrylate (PMMA) cement in a fluid state and at a pressure of between 24 and 30 bar was introduced into the two balloons arranged to cause anterior-posterior expansion using the first inflation device. The anterior-posterior dimension of the implant increased without causing any increase in the cranio-caudal dimension of the implant.

(42) Subsequently, PMMA cement at a pressure of between 24 and 30 bar was introduced into the two balloons arranged to cause cranio-caudal expansion using the second inflation device. The cranio-caudal dimension of the implant increased without causing any increase in the anterior-posterior dimension of the implant.

(43) The PMMA cement was cured. After curing of the PMMA cement, the tubes attached to the balloon catheters were removed. A biomechanical study of the resulting expanded implant showed that it stabilized the L3 and L4 vertebrae.