Vividly simulated prosthetic intervertebral disc

• US 20040193273A1
• Filed: 03/31/2003
• Published: 09/30/2004
• Est. Priority Date: 03/31/2003
• Status: Active Grant

• Current Assignee: Tain-Yew Shi
• Original Assignee: Tain-Yew Shi
• Inventors: Huang, Shih-Shing
• Granted Patent: US 6,893,465 B2
• Time in Patent Office: Days
• US Class Current: 623/17.12
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/441 made of inflatable pockets or chambers filled with fluid, e.g. with hydrogel
• CPC Class Codes: 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
• CPC Class Codes: A61F 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/302 toroidal, e.g. rings
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/30556 for adjusting thickness
• CPC Class Codes: A61F 2002/30563 having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30578 having apertures, e.g. for receiving fixation screws
• CPC Class Codes: A61F 2002/30583 filled with hardenable fluid, e.g. curable in-situ
• CPC Class Codes: A61F 2002/30586 having two or more inflatable pockets or chambers
• CPC Class Codes: A61F 2002/30622 Implant for fusing a joint or bone material
• CPC Class Codes: A61F 2002/30675 Means for regulating synovial fluid pressure
• CPC Class Codes: A61F 2002/30784 Plurality of holes
• CPC Class Codes: A61F 2002/30841 Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/443 having two transversal endplates and at least one intermediate component
• CPC Class Codes: A61F 2002/4495 having a fabric structure, e.g. made from wires or fibres
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• CPC Class Codes: A61F 2210/0085 : hardenable in situ, e.g. epoxy resins
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0041 : using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2230/0065 : toroidal, e.g. ring-shaped, doughnut-shaped
• CPC Class Codes: A61F 2250/0009 : for adjusting thickness
• CPC Class Codes: A61F 2310/00011 : Metals or alloys
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00029 : Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00131 : Tantalum or Ta-based alloys
• CPC Class Codes: A61F 2310/00179 : Ceramics or ceramic-like structures
• CPC Class Codes: A61F 2310/00293 : containing a phosphorus-containing compound, e.g. apatite

Abstract

A prosthetic intervertebral disc includes an upper fusion member gradually fused and secured to an upper vertebra, a lower fusion member gradually fused and secured to a lower vertebra, and a restorable cushioning coupler retained in between the upper and lower fusion members, whereby upon bending or twisting of a patient'"'"'s spine, the upper and the lower fusion members may be flexibly moved with each other for enhancing a free movement of the patient'"'"'s spine and body, as safely resiliently cushioned and easily restored by the cushioning coupler in between the upper and lower fusion members.

Claims

1. A prosthetic intervertebral disc comprising:

an upper fusion member having a biodegradable composition filled or formed therein, and secured to and gradually fused to an upper vertebra;

a lower fusion member having the biodegradable composition filled or formed in said lower fusion member and secured to and gradually fused to a lower vertebrae adjacent to said upper vertebra; and

a restorable cushioning coupler resiliently formed between said upper and lower fusion members;

said restorable cushioning coupler secured to one said fusion member and flexibly engaging with the other said fusion member to thereby flexibly couple the upper and lower vertebrae.

2. A prosthetic intervertebral disc according to claim 1, wherein said upper fusion member includes:

an upper fusion cage having the biodegradable fusion composition filled or preformed in the upper fusion cage, an upper implanting plate formed on an upper portion of the upper fusion cage to be secured to the upper vertebra, a base plate formed on a bottom portion of the upper fusion cage having a pivoting ball axially protruding downwardly from the base plate about a longitudinal axis defined at a longitudinal center of the prosthetic disc and having an outer skirt generally spherically shaped and protruding downwardly from the base plate for protectively surrounding the restorable universal cushioning coupler in cooperation with the lower fusion member.

3. A prosthetic intervertebral disc according to claim 2, wherein said outer skirt of the upper fusion member has a height slightly larger than a half distance of the distance spaced in between the upper and lower vertebrae;

said outer skirt defining a curvature having a center thereof aligned with the longitudinal axis of the prosthetic intervertebral disc when normally positioned in between the upper and lower vertebrae.

4. A prosthetic intervertebral disc according to claim 2, wherein said pivoting ball as axially protruded downwardly from the upper fusion member about the longitudinal axis of the intervertebral disc has a center of the ball aligned with the center of a curvature of the outer skirt.

5. A prosthetic intervertebral disc according to claim 1, wherein said lower fusion member includes:

a lower fusion cage having the biodegradable fusion composition filled or preformed in the lower fusion cage, a lower implanting plate formed on a bottom portion of the lower fusion cage to be secured to the lower vertebra, a supporting base plate formed on an upper portion of the lower fusion cage having an inner skirt generally spherically shaped and protruding upwardly from the supporting base plate to be concentric to an outer skirt of the upper fusion cage for engaging the restorable universal cushioning coupler on the inner skirt and on the supporting base plate of the lower fusion member.

6. A prosthetic intervertebral disc according to claim 1, wherein each said fusion member is formed with a least a drainage hole for discharging liquid as biodegraded from the biodegradable composition filled therein, and having at least a lug protruding from the fusion member to be secured to the vertebra.

7. A prosthetic intervertebral disc according to claim 1, wherein each said fusion member is formed with a plurality of teeth to be fastened to an end plate of each said vertebra, and a plurality of fusion holes formed through the fusion member to allow the bone ingrowth from the vertebra into the fusion member.

8. A prosthetic intervertebral disc according to claim 1, wherein said inner skirt of the lower fusion member has a height slightly larger than a half distance of the distance spaced in between the upper and lower vertebrae;

said inner skirt defining a curvature having a center thereof aligned with a longitudinal axis of the prosthetic intervertebral disc when normally positioned in between the upper and lower vertebrae;

said inner skirt having a curvature center as same as that of the outer skirt.

9. A prosthetic intervertebral disc according to claim 5, wherein said inner skirt and the outer skirt cooperatively define an annular chamber between the inner and outer skirts allowing a relative tangential movement whenever performing a bending, twisting or rotational movement of the patient'"'"'s spinal vertebrae;

and providing a space for retracting or expanding the inner and outer skirts for minimally invasive surgery.

10. A prosthetic intervertebral disc according to claim 9, wherein said annular chamber as defined between the outer and inner skirts is filled therein with a buffer liquid which is bio-compatible.

11. A prosthetic intervertebral disc according to claim 1, wherein said restorable cushioning coupler includes:

a lower cushioning portion secured to a supporting base plate of the lower fusion member, an upper cushioning portion protruding upwardly from the lower cushioning portion to be slidably contacted with a base plate of the upper fusion member, a sealing flap circumferentially formed on a lower perimeter of the cushioning coupler to be slidably engageable with an outer skirt of the upper fusion member for shielding a free-end edge portion of the outer skirt and for sealing a port between the sealing flap and the outer skirt, and a spherical recess recessed in a central portion of the upper cushioning portion to be universally engageable with a pivoting ball formed on the upper fusion member for universally coupling the upper fusion member with the lower fusion member which is formed with the cushioning coupler;

said coupler having a wear-resistance layer formed on an upper surface of the upper cushioning portion and on a surface of the recess.

12. A prosthetic intervertebral disc according to claim 11, wherein said cushioning coupler is formed as a bellows.

13. A prosthetic intervertebral disc according to claim 11, wherein said pivoting ball has a neck portion having a diameter (N) less than a diameter (D) of the ball;

and the spherical recess having a narrowing port engageable with the neck portion of the ball and having a port diameter (N) of the narrowing port smaller than the diameter (D) of the spherical recess for ensuring a stable coupling of the ball with the recess;

the diameter (D) of the ball being equal to that of the spherical recess.

14. A prosthetic intervertebral disc according to claim 11, wherein said cushioning coupler includes a cushioning sac filled with a viscous liquid therein, having an inflating valve protruding outwardly through the lower fusion member for injecting the viscous liquid into the sac.

15. A prosthetic intervertebral disc according to claim 1, wherein said upper and lower fusion members are circumferentially connected and covered by a flexible cover.

16. A prosthetic intervertebral disc according to claim 1, wherein said cushioning coupler includes an inflatable balloon having an elastomer foam encapsulated in a flexible cover, whereby upon foaming of said elastomer foam in said balloon and upon fusion of each said fusion member with each vertebra, said balloon will resiliently flexibly couple said upper and flower fusion members with said upper and lower vertebrae respectively fused to said two fusion members.

17. A prosthetic intervertebral disc comprising a fusion cage secured in between an upper vertebra and a lower vertebra;

having a biodegradable composition formed or filled in said cage, including a plurality of ingredients of different degradation or decomposing rates and an elastomer or flexiable material incorporated in said biodegradable composition;

said biodegradable composition with said cage providing an initial supporting strength and occupying a space between said upper and lower vertebrae and said biodegrable composition having a degradation rate equal to a bone ingrowth rate growing from said vertebrae into said cage;

whereby upon gradual degradation of said composition, the bone ingrowth from either said vertebra will fuse into said cage to form a completely fused intervertebral disc for joining the upper and lower vertebrae.

18. A prosthetic intervertebral disc according to claim 17, wherein said biodegradable composition comprises:

a hydrate of calcium sulfate, a hydrate of tri-calcium phosphate, hydroxyapatite, polylactic acid, and fillers.

19. A prosthetic intervertebral disc according to claim 17, wherein said biodegradable composition forms a composite skeleton or scaffold with reinforcing wires.

20. A prosthetic intervertebral disc comprising a fusion cage secured in between an upper vertebra and a lower vertebra;

having a biodegradable composition formed or filled in said cage, including a plurality of ingredients of different degradation or decomposing rates;

said biodegradable composition with said cage providing an initial supporting strength and occupying a space between said upper and lower vertebrae; and

said biodegrable composition having a degradation rate equal to a bone ingrowth rate growing from said vertebrae into said cage;

whereby upon gradual degradation of said composition, the bone ingrowth from either said vertebra will fuse into said cage to form a completely fused intervertebral disc for joining the upper and lower vertebra.