WO2021042156A1

WO2021042156A1 - Vertebral distractor and surgical systems and methods

Info

Publication number: WO2021042156A1
Application number: PCT/AU2020/000102
Authority: WO
Inventors: Yves Arramon
Original assignee: Simplify Medical Pty Limited
Priority date: 2019-09-04
Filing date: 2020-09-04
Publication date: 2021-03-11

Abstract

A vertebral distractor and surgical system and method using a vertebral distractor includes space saving offset arms which improve speed and reliability of spinal surgery procedures. The surgical bone distractor instrument includes a distractor body and first and second distractor arms. Each of the first and second distractor arms has a proximal end attached to the distractor body and parallel distal ends configured to be secured to bone screws or pins. The first and second distractor arms are bent in a shape such that a space between the proximal ends of the first and second distractor arms is larger than a space between the distal ends of the first and second distractor arms to provide additional space for visualization of a surgical site as well as for insertion of surgical instruments which do not fit between the distal ends of the distractor arms.

Description

VERTEBRAL DISTRACTOR AND SURGICAL SYSTEMS AND METHODS

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. provisional patent application number 62/895,607 (WSGR Docket No. 29850-737.101) filed September 4, 2019, the entire contents of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1 Field of the invention. The present invention relates to medical devices and methods. More specifically, the invention relates to vertebral distractors and surgical systems and methods using a vertebral distractor with space saving offset arms.

[0003] Back pain takes an enormous toll on the health and productivity of people around the world. According to the American Academy of Orthopedic Surgeons, approximately 80 percent of Americans will experience back pain at some time in their life. On any one day, it is estimated that 5% of the working population in America is disabled by back pain.

[0004] Common causes of back pain are injury, degeneration and/or dysfunction of one or more intervertebral discs. Intervertebral discs are the soft tissue structures located between each of the thirty-three vertebral bones that make up the vertebral (spinal) column. Essentially, the discs allow the vertebrae to move relative to one another. The vertebral column and discs are vital anatomical structures, in that they form a central axis that supports the head and torso, allow for movement of the back, and protect the spinal cord, which passes through the vertebrae in proximity to the discs. With age, intervertebral disks begin to shrink. In some cases, they may collapse completely and cause the bones to rub against one another. This is also referred to as osteoarthritis.

[0005] When a damaged intervertebral disc causes a patient pain and discomfort, surgery is often required. Typically, surgical procedures for treating damaged intervertebral discs involve discectomy (partial or total removal of a disc), often followed by interbody fusion of the superior and inferior vertebrae adjacent to the disc or implantation of an intervertebral prosthetic disc. In order for a surgeon to perform a discectomy, fusion procedure, and/or other surgical procedure on the intervertebral disc, a distractor is used to separate the vertebrae and provide space for the surgical procedure. A vertebral distractor attaches to distractor pins or screws inserted into the vertebrae above and below the disc to be treated and applies a force to spread the vertebrae apart. [0006] An alternative to spinal fusion which doesn’t limit patient mobility is intervertebral disc replacement (TDR), also called total disc arthroplasty. The TDR procedure involves removing the natural disk from between the vertebrae and replacing it with an artificial disc prosthesis. The TDR procedure also requires distraction of the vertebrae to access the disc space and commonly uses a vertebral distractor such as a Caspar distractor.

[0007] The Caspar Distractor was developed by Wolfhard Caspar and is the most popular method of cervical spinal distraction used today. Currently available vertebral distractors include a ratchet mechanism connected to a pair of arms. The arms are placed onto distractor screws or pins which have been placed into the patient’s vertebrae. Challenges with these known instruments and techniques include difficulty in viewing and accessing the surgical site due to the location of the arms and racket mechanism. It would be desirable to provide a vertebral distractor and a surgical instrument system with curved, offset distractor arms which allow easy access to the patient anatomy and improved visibility.

[0008] Therefore, a need exists for a vertebral distractor and surgical system and method using a vertebral distractor with space saving offset arms which improve speed and reliability of spinal surgery procedures.

[0009] 2 Description of the Background Art. A variety of intervertebral disc prosthesis designs and methods of implanting are described in described in U.S. Patent Nos. 7,442,211 ; 7,531,001; 7,575,599; 7,585,326; 7,637,913; 7,753,956; 8,206,449; 8,685,035; 8,764,833; 8,808,384; 9,011,544 and 9,351,846, and U.S. Patent Application No. 15/842,663, each of which is incorporated herein by reference in its entirety.

BRIEF SUMMARY OF THE INVENTION

[0010] According to one aspect of the invention, a surgical bone distractor instrument includes a distractor body and first and second distractor arms. Each of the first and second distractor arms has a proximal end attached to the distractor body and parallel distal ends configured to be secured to bone screws or pins. The first and second distractor arms are bent in a shape such that a space between the proximal ends of the first and second distractor arms is larger than a space between the distal ends of the first and second distractor arms. A distraction mechanism on the distractor body is configured to apply a distraction force to the proximal ends of the first and second distractor arms.

[0011] In accordance with another aspect of the invention, a surgical bone distractor system includes a surgical bone distractor instrument, a pair of bone screws or pins and a surgical instrument to be inserted once the vertebrae have been distracted. The surgical bone distractor includes a distractor body and first and second distractor arms. Each of the first and second distractor arms has a proximal end attached to the distractor body and parallel distal ends configured to be secured to bone screws or pins. The first and second distractor arms are bent in a shape such that a space between the proximal ends of the first and second distractor arms is larger than a space between the distal ends of the first and second distractor arms. A distraction mechanism on the distractor body is configured to apply a distraction force to the proximal ends of the first and second distractor arms. The pair of bone screws or pins is configured to be received in the distal ends of the first and second distractor arms. The surgical instrument has a portion which fits between the proximal ends of the first and second distractor arms but does not fit between the distal ends of the first and second distractor arms.

[0012] In accordance with another aspect of the invention, a method of performing spine surgery with a surgical bone distraction instrument includes attaching first and second bone screws or pins to first and second vertebrae of a patient’s spine; providing a surgical bone distractor instrument; attaching distal ends of the first and second distractor arms to the first and second bone screws; applying a distraction force to the first and second vertebrae with the distractor instrument; and inserting a surgical instrument between the first and second distractor arms, wherein the surgical instrument has a portion which fits between the proximal ends of the first and second distractor arms but does not fit between the distal ends of the first and second distractor arms. The surgical bone distractor includes a distractor body; first and second distractor arms, wherein each of the first and second distractor arms has a proximal end attached to the distractor body, parallel distal ends configured to be secured to bone screws or pins, wherein the first and second distractor arms are bent in a shape such that a space between the proximal ends of the first and second distractor arms is larger than a space between the distal ends of the first and second distractor arms; and a distraction mechanism on the distractor body configured to apply a distraction force to the proximal ends of the first and second distractor arms;

BRIEF DESCRIPTION OF THE DRAWINGS [0013] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

[0014] FIG. 1 is a perspective view of a known vertebral distractor;

[0015] FIG. 2 is a perspective view of a vertebral distractor with offset arms; [0016] FIG. 3 is a perspective view of an alternative embodiment of a vertebral distractor with articulating offset arms;

[0017] FIG. 4 is a bottom view of the instrument of FIG. 3;

[0018] FIG. 5 is a front view of the instrument of FIG. 3;

[0019] FIG. 6 is a left side view of the instrument of FIG. 3; and

[0020] FIG. 7 is a perspective view of a removable stop for a surgical instrument.

DETAILED DESCRIPTION OF THE INVENTION [0021] Distraction of spinal vertebrae to provide access to an intervertebral disc is an important part of a successfully spine surgery procedure. Spinal procedures requiring distraction may include vertebral distraction include total disc replacement (TDR), spinal fusion, laminectomy, foraminotomy, discectomy, or spinal implant. Positioning of a distraction instrument in the spine to provide access for spinal surgery can block the surgeon’s view and/or access to some of the disc space or surrounding anatomy.

[0022] FIG. 1 is a perspective view of a known vertebral distractor 10 having a ratchet mechanism 20 and arms 30 which are attachable to distractor pins. Distractor pins or screws have a first end which is formed as a bone screw for attachment to bone, such as a vertebra and a second end which is configured to be received within an open end of the Caspar distractor arms. The arms of the known vertebral distractor of FIG. 1 are bent so that the ratchet mechanism of the distractor can be placed out of the line of vision and the line of access for the surgical site. [0023] FIG. 2 is a perspective view of a surgical distractor 100 for distracting bones such as vertebrae. The distractor 100 includes offset distractor arms 110. The space saving offset arms 110 provide improved access and visibility of the surgical site and increase speed and reliability of spinal surgery procedures. The distractor 100 includes a distractor body 120 which may include any of the known ratchet mechanisms for use in surgical instruments. The distractor arms 110 include first and second distractor arms each having a proximal end attached to the distractor body 120 and substantially parallel distal ends configured to be secured to bone screws or pins. The distal ends of the distractor arms are attached to bone screws or distractor pins (Caspar pins) by placing a central opening or axial opening in the distal ends of the arms onto the pins. The first and second distractor arms 110 are bent in a shape such that a space between the proximal ends of the distractor arms is larger than a space between the distal ends of the distractor arms. For example, in the embodiment of FIG. 2, the distance between the distal ends of the arms is D1 and the distance between the proximal ends of the arms is D2. It should be understood that the distances D1 and D2 will changes as the rachet mechanism of the distractor is activated while the relationship between the distances D1 and D2 continues to be D2 is greater than Dl.

[0024] In the embodiment of FIG. 2, a first arm is attached to an end of a ratchet bar 122 having rachet teeth (not shown) and the second arm is attached to a sleeve 124 of the ratchet mechanism which is slidable over the ratchet bar to apply a distraction force to the proximal ends of the first and second distractor arms. The rachet mechanism of FIG. 2 is activated by a thumb screw 126, however, any known activation mechanism and rachet combination can be used. [0025] The first and second distractor arms of FIG. 2 each have two bends including a first bend 114 and a second bend 116. The first bend 114 allows the distractor body 120 to be out of the way of the surgical instrument insertion path similar to the bent arms of the distractor 10 of FIG. 1. The first bend 114 and second bend 116 together provide an offset which functions to allow the extra space D2 for the surgical instrument insertion described above.

[0026] Although the distractor arms 110 have been shown as having the same offset distance and being mirror images of one another, it should be understood that the offsets of the two arms can be different. In addition, the distractor arms 110 have been shown as having a bend or angled portion located in the same plane as a distraction plane in which the distal ends of the parallel arms reside. However, the distractor arm bend can also be somewhat out of the distraction plane.

[0027] FIGS. 3-6 show an alternative embodiment of a distractor 200 with articulating offset arms 210. Each of the arms 210 has a parallel distal portion 212, a bent portion 214, a hinge portion 216 and a proximal portion 218 which attaches to the distractor body 220. The parallel distal ends 212 of the first and second distractor arms lie in a distraction plane. The first and second distractor arms are bent at the bent portions 214 in the distraction plane to provide an insertion space between the proximal portions 218 of the distractor arms for placement of surgical instruments. The distractor body 220 which may include any of the known ratchet mechanisms for use in surgical instruments. As in the embodiment of FIG. 2, the first arm is connected to a ratchet bar 222 having rachet teeth (not shown) and the second arm is attached to a sleeve 224 of the ratchet mechanism which is slidable over the ratchet bar to apply a distraction force to the proximal ends of the first and second distractor arms.

[0028] An amount of the offset of the distractor arms 110, 210 can vary depending on the space needed for a particular surgical procedure. In one example, the arms have an offset distance of at least 5 mm each which provides an additional 10 mm of space between the proximal portions 218 of the arms for delivery of instruments. The total offset distance of the vertebral distractor D_0ff= (D2-D1). The offset distance of each arm in a distractor having mirror image arms is D₀ff arm = (D2-Dl)/2. The total offset distance D₀ff is about 4-32 mm, preferably 10-20 mm.

[0029] The activation mechanism used for activating the ratchet to move the distractor arms away from each other is not shown in FIGS. 3-6 and can include any of the known activator mechanisms for instruments including one or more rotatable knobs, movable levers or other known ratchet mechanisms.

[0030] FIG. 7 is a perspective view of a removable stop 300 which is one example of a surgical instrument which may be used with the distractor and can take advantage of the additional space provided by the offset arms. The removable stop 300 is attachable to a surgical instrument, such as a cutting instrument or an inserting instrument by attaching the stop to the instrument shaft. The stop has a height or dimension D3 which can fit within the dimension D2 of the distractor of FIGS. 2-6, while the dimension D3 would not fit within the dimension D1 of the distractor distal arms.

[0031] In use in performing spine surgery with the surgical bone distraction instrument 100, 200 the surgical bone distractor is attached to first and second bone screws or pins which have been placed into vertebrae of a patient’s spine. A distraction force is applied to the first and second vertebrae with the distractor instrument. Once a desired distraction is reached, a surgical instrument can be inserted between the first and second distractor arms. The surgical instrument is an instrument, such as the removable stop 300 of FIG. 7 having a portion which fits between the proximal ends of the first and second distractor arms but does not fit between the distal ends of the first and second distractor arms.

[0032] Modification of the above-described assemblies and methods for carrying out the invention, combinations between different variations as practicable, and variations of aspects of the invention that are obvious to those of skill in the art are intended to be within the scope of the invention disclosure.

Claims

WHAT IS CLAIMED IS:

1. A surgical bone distractor instrument comprising: a distractor body; first and second distractor arms, wherein each of the first and second distractor arms has a proximal end attached to the distractor body, substantially parallel distal ends configured to be secured to bone screws or pins, wherein the first and second distractor arms are bent in a shape such that a space between the proximal ends of the first and second distractor arms is larger than a space between the distal ends of the first and second distractor arms; and a distraction mechanism on the distractor body configured to apply a distraction force to the proximal ends of the first and second distractor arms.

2. The instrument of claim 1, wherein the first and second distractor arms are each formed of a single piece from the distal end to the proximal end.

4. The instrument of claim 1, wherein the first and second distractor arms are each formed of two parts connected by a hinge.

5. The instrument of claim 4, wherein the first and second distractor arm hinges are configured to allow a user to adjust an angle of the distractor body with respect to the distraction plane.

6. A surgical bone distractor instrument comprising: a distractor body; first and second distractor arms, wherein each of the first and second distractor arms has a proximal end attached to the distractor body and substantially parallel distal ends configured to be secured to bone screws or pins, wherein the distal ends of the first and second distractor arms lie in a distraction plane, wherein the first and second distractor arms are bent in the distraction plane to provide an insertion space between the proximal ends of the first and second distractor arms for placement of surgical instruments; and a distraction mechanism on the distractor body configured to apply a distraction force to the proximal ends of the first and second distractor arms.

7. The instrument of claim 6, wherein the first and second distractor arms are each formed of a single piece from the distal end to the proximal end.

8. The instrument of claim 6, wherein the first and second distractor arms are each formed of two parts connected by a hinge.

9. The instrument of claim 8, wherein the first and second distractor arm hinges are configured to allow a user to adjust an angle of the distractor body with respect to the distraction plane.

10. A surgical bone distractor system comprising: a surgical bone distractor instrument comprising: a distractor body; first and second distractor arms, wherein each of the first and second distractor arms has a proximal end attached to the distractor body, substantially parallel distal ends configured to be secured to bone screws or pins, wherein the first and second distractor arms are bent in a shape such that a space between the proximal ends of the first and second distractor arms is larger than a space between the distal ends of the first and second distractor arms; and a distraction mechanism on the distractor body configured to apply a distraction force to the proximal ends of the first and second distractor arms; a pair of bone screws or pins configured to be received in the distal ends of the first and second distractor arms; and a surgical instrument having a portion which fits between the proximal ends of the first and second distractor arms but does not fit between the distal ends of the first and second distractor arms.

11. The system of claim 10, wherein the surgical instrument includes a removable stop including the portion which fits between the proximal ends of the first and second distractor arms but does not fit between the distal ends of the first and second distractor arms.

12. The system of claim 10, wherein the first and second distractor arms are each formed of a single piece from the distal end to the proximal end.

13. The instrument of claim 10, wherein the first and second distractor arms are each formed of two parts connected by a hinge.

14. The instrument of claim 13, wherein the first and second distractor arm hinges are configured to allow a user to adjust an angle of the distractor body with respect to the distraction plane.

15. A method of performing spine surgery with a surgical bone distraction instrument, the method comprising: attaching first and second bone screws or pins to first and second vertebrae of a patient’s spine; providing a surgical bone distractor instrument comprising: a distractor body; first and second distractor arms, wherein each of the first and second distractor arms has a proximal end attached to the distractor body, substantially parallel distal ends configured to be secured to bone screws or pins, wherein the first and second distractor arms are bent in a shape such that a space between the proximal ends of the first and second distractor arms is larger than a space between the distal ends of the first and second distractor arms; and a distraction mechanism on the distractor body configured to apply a distraction force to the proximal ends of the first and second distractor arms; attaching the distal ends of the first and second distractor arms to the first and second bone screws; applying a distraction force to the first and second vertebrae with the distractor instrument; and inserting a surgical instrument between the first and second distractor arms, wherein the surgical instrument has a portion which fits between the proximal ends of the first and second distractor arms but does not fit between the distal ends of the first and second distractor arms.