Transpedicular screw and rod system

• US 4,805,602 A
• Filed: 11/03/1986
• Issued: 02/21/1989
• Est. Priority Date: 11/03/1986
• Status: Expired due to Term

• Current Assignee: EBI LLC (Zimvie Incorporated)
• Original Assignee: Danninger Medical Technology, Inc. (Interpore Spine Limited)
• Inventors: Puno, Rolando M., Kelly, Kevin A.
• Primary Examiner(s): Apley, Richard J.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/926,386
• Time in Patent Office: 841 Days
• Field of Search: 128/92 YM, 128/92 YF, 128/92 Z, 128/69, 403/342, 24/486, 24/135 N, 24/130, 24/135 R, 623/16, 623/17, 82/37, 248/251, 248/316.6, 211/123, 211/7, 411/400, 411/401
• US Class Current: 606/267
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7037 wherein pivoting is blocked when the rod is clamped
• CPC Class Codes: A61B 17/7055 connected to sacrum, pelvis or skull
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: Y10T 24/3967 Bolt perpendicular to cable axis
• CPC Class Codes: Y10T 24/44265 Gripping member face integral with or rigidly affixed to screw-driving portion
• CPC Class Codes: Y10T 403/67 Thimble: screw or cam
• CPC Class Codes: Y10T 403/7188 Rod received in open channel

Abstract

An apparatus is provided for the internal fixation of the spine. The apparatus comprises two sets of implants each consisting of a rod and a plurality of vertebral anchors. A set of implants is positioned on the spine on either side of the spinous process spanning the portion of spine to be immobilized. The rod is secured to the vertebral laminae by the vertebral anchors. The anchor includes a transpedicular screw member which is secured to a vertebrae. A rod support includes a cup which captures the screw and optionally permits micromotion between the rod support and screw. The rod support also includes a rod-receiving channel which captures the rod. A clamp is provided to secure the rod in the channel.

Claims

1. An anchor which secures a rod to a bone for the stabilization of the bone comprising:

attachment means comprising a screw including a head and a threaded portion, the head having a larger outer diameter than the outer diameter of the threaded portion to define a rear shoulder;

rod support means having a longitudinal axis and being attached to the bone about the longitudinal axis by the attachment means, the rod support means including a rod-receiving channel transverse to the longitudinal axis, the rod support means further including a cup having a rear opening and a hollow central recess, the cup also having a flange projecting into the rear opening, the hollow central recess receiving the head of the screw so that the threaded portion extends through the rear opening and the rear shoulder of the screw cooperates with the flange and is thereby adapted to hold the rod support means against a bone while allowing movement between the screw and the rod support means;

a threaded clamp that engages the cup member of the rod support means and which cooperates with the rod support means to capture the rod independently of the engagement between said rear shoulder and said flange; and

an annular collar having threads which engage the threads of the clamp such that rotating the collar in relation to the cup exerts a compressive force on the rod to clamp the rod into position.

2. An apparatus for maintaining vertebrae in a desired relationship as set forth in claim 1 wherein said rod support includes means to secure the rod support from twisting axially out of alignment.

3. An internal fixation apparatus as set forth in claim 1 wherein:

said screw portion and said rod support are two members;

said screw portion having a threaded portion and a head, the rear portion of the head having a rounded shoulder;

the rod support including a cup portion having a central longitudinal opening, the rod support including at one end the channel and at the other end the central opening including a restricted diameter forming a lip which is smaller than the maximum diameter of the head such that when the screw is inserted through the central opening, the rounded shoulder engages the lip to form a ball-and-socket joint.

4. A device for the stabilization of one or more bone segments comprising two sets of implants, each implant set comprising:

a rod; and

at least two anchors, each anchor comprising a screw;

rod support means having a longitudinal axis and being adapted to be attached to a bone by a screw which extends into the bone along said longitudinal axis, so that the rod support means is held against the bone while allowing movement between the screw and the rod support means, the rod support means further including a rod-receiving channel transverse to the longitudinal axis;

a threaded clamp that engages the rod support means and which cooperates with the rod support means to capture the rod independently of the engagement between the screw and the rod support means; and

an annular collar having threads that engage the threads of the clamp such that rotating the collar in relation to the rod support means exerts a compressive force on the rod to clamp the rod into position.

5. A device for the stabilization of one or more bone segments as set forth in claim 4 wherein:

the screw includes a hear and a threaded portion, the head having a larger outer diameter than the outer diameter of the threaded portion to define a rear shoulder; and

the rod support means including a cup having a rear opening defining a flange projecting into the opening and a hollow central recess which receives the head of the screw so that the threaded portion extends through the rear opening and the rear shoulder of the screw cooperates with the flange to hold the rod support against the bone while allowing movement between the screw and the rod support.

6. An internal fixation apparatus for maintaining vertebrae in a desired relationship comprising:

a rod which is rigid and is biocompatible;

a plurality of vertebral anchors adapted to be positioned on the side of the spinous processes on the posterior surface of the transverse processes and the laminae and each anchor comprising

a screw,

a rod support which is adapted to be held to the vertebrae by the screw so that the rod support is held against a vertebrae while allowing movement between the screw and the rod support, the rod support having a channel which receives one of the rods,

a threaded clamp that engages the rod support and which cooperates with the rod support to capture the rod independently of the engagement between the screw and the rod support; and

an annular collar having threads that engage the threads of the clamp such that rotating the collar in relation to the rod support exerts a compressive force on the rod to clamp the rod into position.

7. A device for the posterior stabilization of the spine comprising two sets of spinal implants, each one adapted to be positioned on either side of the spinous process, each said of spinal implants comprising:

a rod; and

at least vertebral anchors, each anchor comprising

rod support means having a longitudinal axis and including

a cup having a rear opening defining a flange and a hollow central recess along the longitudinal axis, and

two opposite laterally-extending brackets which form a rod-receiving channel transverse to the longitudinal axis;

a transpedicular screw having a head defining a rear shoulder and a thread portion, the screw being engaged by the cup so that the rear shoulder cooperates with the flange and is thereby adapted to hold the rod support means against a bone while allowing movement between the screw and the rod support means;

an externally-threaded clamp having a central arch which cooperates with the rod support to enclose the rod between the central arch and the rod-receiving channel; and

an internally-threaded annular collar which cooperates with the externally-threaded portion of the clamp and the brackets to cause the clamp and the rod support to apply compressive force to the rod when the collar is tightened in relation to the clamp and is thereby adapted to hold the rod support means against a bone while allowing movement between the screw and the rod support means.