Apparatus for subcutaneous suprafascial pedicular internal fixation

• US 5,569,248 A
• Filed: 05/09/1995
• Issued: 10/29/1996
• Est. Priority Date: 03/17/1992
• Status: Expired due to Term

• Current Assignee: SDGI Holdings Incorporated (Medtronic Plc)
• Original Assignee: Danek Medical, Inc.
• Inventors: Mathews, Hallett H.
• Primary Examiner(s): ISABELLA, DAVID J
• Application Number:
  US08/437,523
• Time in Patent Office: 539 Days
• Field of Search: 623/16, 623/17, 606/60, 606/61, 606/65, 606/72, 606/73
• US Class Current: 606/264
• CPC Class Codes: A61B 17/70 Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
• CPC Class Codes: A61B 17/7007 Parts of the longitudinal elements, e.g. their ends, being specially adapted to fit around the screw or hook heads
• CPC Class Codes: A61B 17/7049 Connectors, not bearing on the vertebrae, for linking longitudinal elements together A61B17/7055, A61B17/7053, A61B17/7019 take precedence
• CPC Class Codes: A61B 17/7059 Cortical plates A61B17/7007, A61B17/7058 take precedence
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• 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 2002/2839 Bone plugs or bone graft dowels
• CPC Class Codes: A61F 2002/30329 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2002/448 comprising multiple adjacent spinal implants within the same intervertebral space or within the same vertebra, e.g. comprising two adjacent spinal implants
• CPC Class Codes: A61F 2002/449 comprising multiple spinal implants located in different intervertebral spaces or in different vertebrae
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements

Abstract

A system and method for internal fixation of vertbra of the spine to facilitate graft fusion is disclosed which minimizes the degee of trauma and the amount of surgical invasion. In one aspect the system includes fixation hardware which is inserted through small incisions aligned with each pedicle to be instrumented. The hardware includes bone screws, fixation plates, engagement nuts, and linking members. In an important feature of the hardware, the fixation plates, engagement nuts and linking members are supported suprafascially but subcutaneously so that the fascia and muscle tissue are not damaged, by a bone screw which includes an elongated smooth shank intermediate bone engaging threads and machine threads that is configured to support the fixation hardware above the fascia.

Claims

1. The spinal fixation system for internal fixation of the spine of a human patient, comprising:

an elongated fixation element configured to be implanted under the skin of a patient spanning between at least two vertebrae;

at least two bone engaging fasteners each having an elongated shank with a first end and an opposite second end, the shank including bone engaging threads defined at said first end for engagement into one of the at least two vertebrae, and a smooth shank portion extending from said bone engaging threads toward said second end, said smooth shank portion having a length approximately equal to the distance from a pedicle of the one vertebra to the muscle fascia posterior of the one vertebra when said bone engaging threads are disposed within the one vertebra, said bone engaging threads extending a length from said first end that is approximately equal to said length of said smooth shank portion; and

means for clamping said elongated fixation element to each of said at least two bone engaging fasteners at said second end thereof so that said fixation element is positioned above the muscle fascia of the patient.

2. The spinal fixation system of claim 1, further comprising:

a pair of guide pins adapted to be inserted into the pedicle of the vertebra; and

a cannulated bore defined in each of said pair of bone engaging fasteners from said first end to said second end to permit advancement of said fasteners over a corresponding one of said guide pins when said pins are inserted into a pedicle.

3. The spinal fixation system of claim 1, wherein said elongated fixation element is a spinal plate defining a number of openings therein adapted to receive said second end of said shank of each bone engaging fastener therethrough.

4. The spinal fixation system of claim 3, wherein said means for clamping includes:

a machine threaded portion defined on said shank between said second end and said smooth shank portion, said machine threaded portion being received through one of said number of openings in said spinal plate; and

a threaded nut adapted to engage said machine threaded portion to clamp said spinal plate between said nut and said hub.

5. The spinal fixation system of claim 4, wherein said machine threaded portion has a length less than the distance between the muscle fascia and the outer skin layer of the patient.

6. The spinal fixation system of claim 1, wherein said elongated shank of each of said bone engaging fasteners has a length from said second end to said bone engaging threads that is less than the distance between the pedicle of the vertebra and the outer skin layer of the patient.

7. The spinal fixation system of claim 3, wherein said means for clamping includes a hub integrally formed on said shank near said machine threaded portion, said hub defining a support surface for supporting said spinal plate thereon.

8. A spinal fixation system for internal fixation of the spine of a human patient, comprising:

an elongated fixation element configured to be implanted under the skin of a patient spanning between at least two vertebrae;

at least two bone engaging fasteners each having an elongated shank with a first end and an opposite second end, the shank including bone engaging threads defined at said first end for engagement into one of the at least two vertebrae, and a smooth shank portion extending from said bone engaging threads toward said second end, said smooth shank portion having a length approximately equal to the distance from a pedicle of the one vertebra to the muscle fascia posterior of the one vertebra when said bone engaging threads are disposed within the one vertebra, said shank further including a machine threaded portion between said second end and said smooth shank portion, said machine threaded portion having a length less than the distance between the muscle fascia and the outer skin layer of the patient; and

means for clamping said elongated fixation element to each of said at least two bone engaging fasteners at said second end thereof so that said fixation element is positioned above the muscle fascia of the patient, said means including a threaded nut adapted to engage said machine threaded portion of each of said bone engaging fasteners.