Spreading device for maintaining a predetermined distance between adjacent spinous processes of a vertebral body

Abstract

The invention relates to a spreading device (1) for maintaining a predetermined distance between adjacent spinous processes (21, 22) of a vertebral body, comprising a threaded section (3) having a first end element (310) arranged on a first end section (31) for interlocking contact with a first spinous process (21) of a vertebral body, a second end element (320) arranged on a second end section (32) opposite the first end section (31) for interlocking contact with a second spinous process (22) of a vertebral body, and a screw (4) for adjusting a distance between the first and second end elements (310, 320), in order to brace the first and second end element (310, 320) against the first and second spinous process (21, 22) such that the contacting end elements (310), 320) are clamped.

Description

[0001] Spreading device for maintaining a predetermined distance between adjacent spinous processes of a vertebral body

[0002] The invention relates to a spreading device for maintaining a predetermined distance between adjacent spinous processes of a vertebral body according to the independent claim.

[0003] The invention lies in the technical field of interspinous devices (minimally invasive implant) for opening, enlarging and stabilizing a spinous process space for the therapy and prevention of position-related diseases and deformities of the spine.

[0004] The spinal canal is a cylindrical space in the center of the vertebral column, running axially (vertically in humans, horizontally in domestic animals). Within this space lie the spinal cord and the nerve bundle of the cauda equina, protected by the spinal cord. Diseases of the segmental bony structure can lead to changes such as bony outgrowths (spondylophytes, spondylosis), ligament thickening, and osteoarthritis of the facet joints (spondylarthrosis), which can result in narrowing of the spinal canal (spinal stenosis). These disease-related changes in the shape and position of the bony structures affect the spinal nerves exiting the spinal canal at each segment. Any movement, especially in cases of lumbosacral instability, can lead to progressive narrowing of the spinal canal and painful irritation of the nerves exiting it.Over the course of a person's life, the joints undergo progressive degeneration. This particularly affects the small vertebral joints. Considerable scientific research has already been undertaken to explain the underlying causes. That degeneration is a factor is undisputed. The fact remains that, regardless of the specific causes, the joints and their components change to such an extent that it ultimately leads to misalignments and therapy-resistant spinal pain, significantly impacting quality of life.

[0005] In addition to established conservative and surgical treatments, such as spinal fusion, interspinous spreader systems were initially used successfully. The principle is based on stretching the posterior ligaments to widen the spinal canal and shift the "focal point" ventrally, thereby redirecting the dorsal pressure on the neural structures, particularly the posterior longitudinal ligament, which is richly supplied with nociceptors.

[0006] However, a disadvantage of the known spreading systems is that they lead to progressive degeneration, especially of the intervertebral disc and the small vertebral joints.

[0007] The invention aims to provide a spreading device which overcomes the disadvantages of the prior art and which curbs progressive degeneration, so that major surgery on the spine can be avoided for at least several years.

[0008] The problem is solved by a spreading device for maintaining a predetermined distance between adjacent spinous processes of a vertebral body, comprising the features of independent claim 1. Advantageous embodiments are the subject of the dependent claims.

[0009] The invention comprises a spreading device for maintaining a predetermined distance between adjacent spinous processes of a vertebral body, comprising a threaded section with a first end element arranged on a first end section for positive engagement with a first spinous process of a vertebral body, a second end element arranged on a second end section opposite the first end section for positive engagement with a second spinous process of a vertebral body, and a screw for adjusting the distance between the first and second end elements in order to clamp the first and second end elements against the first and second spinous processes, respectively, so that the adjacent end elements are clamped. This causes a posterior widening of the spinal canal, so that the joint space of the facet joints is also restored by the expansion between the spinous processes.

[0010] One advantageous aspect is that the thread profile of the threaded section engaging with the first and second end elements has the shape of an isosceles trapezoid, with the first and second end sections having opposing threads. This allows the first and second end elements to be driven apart in opposite directions by means of the screws and each clamped against the mandrel process.

[0011] It is particularly advantageous if the helix angle between corresponding flanks of the thread section is in the range of 40–20°, preferably in the range of 25–35°, and most preferably at 30°. This enables optimal force transmission and has the advantage that the thread section can absorb large axial forces.

[0012] According to a preferred aspect, the helix angle between corresponding flanks of the threaded section is smaller than the arctangent of the coefficient of sliding friction of the material pairing between the threaded section and the screw. This results in self-locking of the thread, thus preventing unintentional slippage or rotation of the end elements against the thread. Advantageously, the first and second end elements have a U-shape with a first and a second leg, respectively, to allow for positive engagement with the spinous process of a vertebral body. This ensures that the end elements are brought directly into contact with the spinous process and can be tightened against it without slippage or rotation.

[0013] It has proven advantageous if the first and second legs of the U-shape each have a radius at the open end. This prevents damage to the spinous process by the end elements.

[0014] One advantageous feature is that the first and second end elements include a receiving opening for a fastening element, allowing them to be securely attached to the spinous process of a vertebral body. This enables the end elements to be additionally secured to the spinous process.

[0015] It is particularly advantageous if the screw has a screw head with a hexagonal drive, allowing it to be adjusted using an Allen key. This enables the expanding device to be easily adjusted with a standard Allen key.

[0016] According to a preferred aspect, the screw head drive has a tightening torque in the range of 2 to 6 Nm, preferably 2.5 to 5 Nm, and particularly preferably 3 to 4 Nm. This ensures that the end elements can be securely positioned on the threaded section before failure due to shearing occurs.

[0017] Advantageously, a method for attaching a spreader between adjacent spinous processes of a vertebral body comprises the steps of: a. providing a spreader; b. establishing a positive fit between a first end element and a first spinous process; c. establishing a positive fit between a second end element and a second spinous process; d. setting a distance between the first and second

[0018] end elements to each other, by means of a screw to clamp the first and second end elements against the first and second spinous processes, so that the adjacent end elements are clamped; e. if necessary, fastening the first end element to the first spinous process by means of a first fastening element; and f. if necessary, fastening the second end element to the second spinous process by means of a second fastening element.

[0019] This makes it possible to contain progressive degeneration of the joints, so that major surgery on the spine can be avoided for at least several years.

[0020] The invention will now be explained in more detail with reference to a drawing. The drawing shows:

[0021] Fig. 1 shows a schematic representation of a spreading device according to the invention for arrangement between two adjacent spinous processes of a vertebral body;

[0022] Fig. 2 shows a schematic representation of a spreading device according to the invention arranged between two adjacent spinous processes of a vertebral body in a spine; and

[0023] Fig. 3 shows a spreading device arranged between two adjacent spinous processes of a vertebral body in a spine according to the prior art.

[0024] Fig. 1 shows a spreading device 1 according to the invention for maintaining a predetermined distance between adjacent spinous processes 21, 22 of a vertebral body, comprising a threaded section 3 with a first end element 310 arranged on a first end section 31 for positive engagement with a first spinous process 21 of a vertebral body, a second end element 320 arranged on a second end section 32 opposite the first end section 31 for positive engagement with a second spinous process 22 of a vertebral body, and a screw 4 for adjusting a distance between the first and second end elements 310, 320 in order to clamp the first and second end elements 310, 320 against the first and second spinous processes 21, 22, so that the adjacent end elements 310, 320 are clamped. The aim is to stimulate the production of synovial fluid in order to achieve a "lubrication effect" of the joint surfaces.Synovial fluid also serves, among other things, to nourish the joint surfaces. In addition to the goals already mentioned, the aim is to interrupt the subjective pain arc.

[0025] The screw 4 comprises a screw head with a screw head drive having a hexagon for adjustment by means of an Allen key. The screw head drive has a tightening torque in the range of 2 to 6 Nm, preferably 2.5 to 5 Nm, and particularly preferably 3 to 4 Nm.

[0026] For example, the end elements 310, 320 along the thread are 3 movable jaws.

[0027] The thread profile of thread section 3, which engages with the first and second end elements 310, 320, has the shape of an isosceles trapezoid. Such a thread is called a trapezoidal thread. The first and second end sections 31, 32 have opposing threads.

[0028] The helix angle between corresponding flanks of the thread section 3 lies in a range of 40–20°, preferably in a range of 25–35°, and particularly preferably at 30°. The helix angle between corresponding flanks of the thread section 3 is smaller than the arctangent of the coefficient of sliding friction of the material pairing of the thread section 3 and the screw 4. A method for fastening a spreading device 1 according to the invention between adjacent spine processes 21, 22 of a vortex body comprises the steps: a. providing a spreading device 1; b. establishing a positive-locking connection between a first end element 310 and a first spine process 21; c. establishing a positive-locking connection between a second end element 320 and a second spine process 22; d.Adjusting the distance between the first and second end elements 310, 320 by means of a screw 4 to clamp the first and second end elements 310, 320 against the first and second mandrel extensions 21, 22, so that the adjacent end elements 310, 320 are clamped, e.g., fastening the first end element 310 to the first.

[0029] Spinous process 21 by means of a first fastening element; and, if necessary, fastening of the second end element 320 to the second

[0030] Spinous process 22 by means of a second fastening element.

[0031] Fig. 2 shows a schematic representation of a spreading device 1 according to the invention, which is arranged between two adjacent spinous processes 21, 22 of a vertebral body in a spine.

[0032] The first and second end elements 310, 320 have a U-shape with a first and a second leg, in order to be brought into positive contact with the spinous process 21, 22 of a vertebral body. The first and second legs each have a radius (not shown) at the open end of the U-shape.

[0033] The first and second end elements 310, 320 include a receiving opening (not shown) for a fastening element to be force-fitted to the spinous process 21, 22 of a vertebral body. The fastening element is, for example, a screw.

[0034] Fig. 3 shows a conventional interspinous spreader 1 from the prior art for the treatment of spondylarthrosis in the cervical and lumbar region.

Claims

Patent claims 1. Spreading device (1 ) for maintaining a predetermined distance between adjacent spinous processes (21 , 22) of a vertebral body comprising a threaded section (3) with a first end element (310) arranged on a first end section (31 ) for positive engagement with a first spinous process (21 ) of a vertebral body, a second end element (320) arranged on a second end section (32) opposite the first end section (31 ) for positive engagement with a second spinous process (22) of a vertebral body and a screw (4) for adjusting a distance between the first and second end elements (310, 320) in order to clamp the first and second end elements (310, 320) against the first and second spinous processes (21 , 22) so that the adjacent end elements (310, 320) are clamped.

2. Spreading device (1) according to claim 1, wherein the profile of the threads of the threaded section (3) engaging with the first and second end element (310, 320) has the shape of an isosceles trapezoid and wherein the first and second end section (31, 32) have opposing threads.

3. Spreading device (1) according to one of the preceding claims, wherein the angle of inclination between corresponding flanks of the threaded section (3) is in a range of 40 - 20°, preferably in a range of 25 - 35°, particularly preferably at 30°.

4. Spreading device (1) according to one of the preceding claims, wherein the angle of inclination between corresponding flanks of the threaded section (3) is smaller than the arctangent of the coefficient of sliding friction of the material pairing of the threaded section (3) and the screw (4).

5. Spreading device (1) according to one of the preceding claims, wherein the first and the second end element (310, 320) form a U-shape with a first and a has a second limb in order to be able to be brought into a form-fitting position with the spinous process (21 , 22) of a vertebral body.

6. Spreading device (1) according to one of the preceding claims, wherein the first and second legs at the open end of the U-shape each have a radius.

7. Spreading device (1) according to one of the preceding claims, wherein the first and second end element (310, 320) comprise a receiving opening for a fastening element in order to be force-fitted to the spinous process (21, 22) of a vertebral body.

8. Spreading device (1) according to one of the preceding claims, wherein the screw (4) comprises a screw head with a screw head drive with a hexagon in order to be adjustable by means of an Allen key.

9. Spreading device (1) according to one of the preceding claims, wherein the screw head drive has a tightening torque in a range of 2 to 6 Nm, preferably 2.5 to 5 Nm, particularly preferably 3 to 4 Nm.

10. A method for attaching a spreading device (1) according to one of the preceding claims between adjacent spinous processes (21, 22) of a vertebral body, comprising the steps of: a. providing a spreading device (1); b. establishing a positive fit between a first end element (310) and a first spinous process (21); c. establishing a positive fit between a second end element (320) and a second spinous process (22); d. setting a distance between the first and second end element (310, 320) to each other, by means of a screw (4) around the to clamp the first and second end elements (310, 320) against the first and second spinous processes (21, 22) so that the adjacent end elements (310, 320) are clamped; e. if necessary, fastening the first end element (310) to the first spinous process (21) by means of a first fastening element; and f. if necessary, fastening the second end element (320) to the second spinous process (22) by means of a second fastening element.

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