ES2358494B1 - FLEXIBLE CERVICAL PROSTHESIS. - Google Patents

Abstract

Flexible cervical prosthesis, consisting of an upper housing (1) with a threaded outer area (4), which constitutes a spheroidal cavity (10) on the inside, a lower housing (2) also with a threaded outer area (5) and a socket (12) and between both housings the core (3) is located, formed in turn by two parts, one upper (6) and one lower (7) joined by a heel (9), being these threaded bodies ( 4, 5) adopt longitudinal notches (8), where all the pieces of which this prosthesis is composed are completely transparent radius and are provided with housings to locate radio-opaque bodies.

Description

Flexible cervical prosthesis.

Object of the invention

The present flexible cervical prosthesis is completely transparent radius and has the possibility of damping with a more physiological operation than the current prostheses, with the possibility of damping the movements of fl exo-extension of the spine, which also allows the movements of translation, flexion lateral and rotation; As a consequence of this, this prosthesis helps reduce the degenerative process that the spine undergoes when removing a cervical disc.

It has application in the industry and prosthetic surgery. Background of the invention

The spine (CV) has two fundamental functions:

-

Mechanical, is involved in the union and balance of the skeleton.

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Protective, it protects the spinal cord and all its nerve branches while maintaining the mobility of the trunk.

The mobility of the CV in normal circumstances is determined by the anatomical geometry of its bony and ligamentous structures, the angle formed by the joints. The damping of the loads and the maintenance of the intersomatic space, is ensured by the intervertebral discs.

The vertebral disc is a kind of cartilaginous pad with a large amount of water, which is formed by two components: a semi-fluid internal mass called the nucleus pulposus and a surrounding fibrous band called the fibrous ring. While it is true that the vertebral disc fulfills the function of damping movements with adjacent vertebrae, its main role is the absorption of part of the forces and loads to which it is subjected.

The discology causes a cervical nuchal pain clinic in the patient that can be accompanied by radicular pain that is manifested as pain radiated from the upper limb to the fingers usually accompanied by sensory disorders and eventually loss of strength in the muscle group involved . In the most serious clinical situation there is compression of the cervical cord that causes different degrees of tetraparesis with associated pyramidal activity in the four extremities and sensory-motor involvement.

The development of current mobile disc prostheses tries to preserve the physiological mobility of space and avoid adjacent disc overload.

Vincent Pontillart (2001) designed his own prosthesis that consisted of a titanium ring with polyurethane filler that was fixed in the lower vertebra with a screw, allowing the placement of the prosthesis in adjacent segments. After satisfactory initial results, the prosthesis stopped being used when it was observed that in practically all the operated patients bone growth appeared on the prosthesis, causing the fusion of the segment.

In 1997 Jackowski in Birmingham developed a prosthesis designed to replace the nucleus pulposus and the anterior common vertebral ligament, using an elastomeric silicone core wrapped in a polyester bag with upper and lower wings that serve for fixation in the vertebral bodies.

Other prosthetic designs are: Bryan prosthesis, "Cervidisk", "Prodisc C" and "Charite C" etc ...

The main problems presented by current cervical prostheses are:

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Mid-term arthrodesis (loss of mobility) of the disc space due to bone growth from the margins of the disc plates.

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Incompatibility or artefacts in the MRI that makes it impossible to carry out postoperative control studies if the patient presents a new cervical clinic after the intervention.

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They do not reproduce all the arcs of movement of the spine (facet pain due to overload).

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Incapacity of damping, unphysiological behavior.

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Technically complex placement according to prostheses, with the consequent lengthening of surgical time.

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The instruments for placement are sometimes too complicated depending on the type of prosthesis.

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High economic cost according to prostheses. Description of the invention

The fl exible cervical prosthesis that is advocated is part of a concept of surgical technique already well known as the “Cloward” technique.

This prosthesis is fully compatible with Magnetic Nuclear Resonance (NMR) and other control systems, has mobility and ensures a near-physiological damping.

The prosthesis is composed of three pieces in biocompatible polymer and transparent radius:

The external part is cylindrical and threaded, being formed by two half housings that can be covered with osteoconducting material to ensure a fast fixation in the cervical plates and in its center, the nucleus of the prosthesis is housed as an open piece, which in its upper part adopts a domed conformation in order to reproduce the extension flexion movement, and flat at the bottom to ensure that the position of the core is as close as possible to the physiological axis, by the displacement in the lower housing of the intended housing To that effect.

In the center of the core there is a groove that ensures the possibility of damping the prosthesis if necessary, each element of the prosthesis has an RX control marker.

The described prosthesis has novel advantages in comparison with the mobile prostheses available in the market until now, since one that is completely transparent radius or that has the possibility of damping is not known.

In the first place, the cervical prosthesis that is advocated has a more physiological functioning with the possibility of damping the movements of fl exo-extension of the spine, which also allows movements of translation, lateral flexion and rotation. As a consequence of this, this prosthesis helps reduce the degenerative process that the spine undergoes when removing a disc, the so-called adjacent space syndrome, which can appear to more than 10% of patients operated for cervical disc herniation, arthrodesed with Fixed prostheses and facet pain due to overload or medium-term fusion with most current mobile prostheses.

The placement of the prosthesis is simple, safer, and the instruments required for it are limited and simple in use. These advantages make it possible to shorten surgical times, which reduces the risk of complications.

Due to the composition of the Peek prosthesis (Polyether ether ketone), it does not have artifacts in the NMR, allowing quality postoperative controls.

It should also be noted that the cost of the prosthesis itself, and the overall cost of the herniated disc are significantly reduced. Description of the drawings

To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, a series of fi gures are attached as an integral part of it, which are illustrative and not limiting, the following has been represented:

Figure 1.-Perspective view of a practical embodiment of the flexible cervical prosthesis object of the present invention.

Figure 2.- Elevation, plan and profile view in section between vertebrae of the previous figure.

Figure 3.-Schematic perspective of the lower housing of the prosthesis.

Figure 4.-Elevation and profile, and sections of the plant and other sectioned profile of the upper housing of the previous figure.

Figure 5.-Schematic perspective of the upper housing.

Figure 6.-Elevation and sections of the floor and profile of the lower housing.

Figure 7.-Perspective view of the prosthesis core.

Figure 8.-Elevation plan and profile of the core of the previous figure. Preferred Embodiment of the Invention

The flexible cervical prosthesis object of the present invention consists of an upper housing (1) with a threaded outer area (4), a lower housing (2) also with a threaded outer area (5) and between them the core (3 ), formed in turn by two parts, one upper (6) and one lower (7) joined by a heel (9).

These threaded bodies (4, 5) house longitudinal notches (8) that prevent that once the prosthesis is inserted between the cervical vertebrae, it rotates in the opposite direction, that is, extraction by interference with the vertebrae themselves.

The upper housing (1) constitutes a spheroidal cavity (10) from whose inner surface the outer surface (11) of the part (6) of the core (3) can slide, in the direction of the arrows (A) and (B) according to movements of fl exion-extension and lateral fl exo, so that these surfaces are congruent.

On the other hand, the body (7) forms edges in a manner that prevents it from rotating on its seat, which is arranged in a socket (12) of the lower housing (2). The adjustment between both pieces is that which allows a limited movement of rotation, longitudinal and transverse translation of the core (3) with respect to the lower housing (2) in the direction of the arrow (C, D and E).

All the pieces of which this prosthesis is composed are provided with housings to locate radio-opaque bodies, in order to keep track of the placement of the prosthesis in the spine. The hole (13) of the lower housing (2) serves as an orientation when implanting the prosthesis with the help of an introducer.

Its application and operation is very simple, for this, the placement of the prosthesis is performed after microsurgical removal of the intervertebral disc and cervical hernia with decompression of nerve structures depending on the cases.

A distracting guide is introduced to restore the physiological intervertebral space.

The tunnel is milled through the guide, where the prosthesis will be placed.

Subsequently, with a male, the threading of the tunnel is performed.

With an insert it is placed by threading, the prosthesis in its final situation. Proper placement is checked with a portable X-ray device.

Finally, the surgical incision is closed after the placement of a Redom drain.

The threaded propeller (4, 5) of the respective housings (1, 2), fits with the thread made in the tunnel so that the contact surface between vertebrae (14, 15) is increased, facilitating osseointegration in case of being required by means of the corresponding surface treatment of the carcasses.

On the one hand, the thread prevents the involuntary expulsion of the cervical prosthesis from its housing and on the other, the notches (8) increase the difficulty for the threaded body to rotate in the direction of loosening.

Once the prosthesis is installed in its working situation, the upper housing (1) and the lower housing (2) do not come into direct contact. The movements that the prosthesis allows and that resembles the physiological natural of the spine are that of tilt around the heel (9) of the nucleus (3) while the surface (11) slides on the inside (10) of the housing superior to the point that if the effort on the superior vertebra

(14) the upper part (6) continues to swing on its support in the heel (9) approaching or moving away from the lower part (7) through the opening (16) existing between the two, depending on the direction of the effort. All this, according to the fl exo-extensor movement represented in the arrow (A) and lateral fl exo (B).

When the effort disappears, thanks to the elastic deformation suffered by the core material in its heel (9), the core returns to its resting position. However, this throat can be replaced by another element that performs the function of transmitting loads and suffering elastic deformations.

In turn, this prosthesis allows limited displacement of rotation and translation in the direction of the arrows (C, D and E); this is given by virtue of the fact that the upper carcass (1) forms a caring body with the upper vertebra (14) and the lower carcass (2) with the lower vertebra (15), and that, given the efforts of the column that require this game, the bottom (7) of the core has a path inside the socket

(12) of the lower housing (2).

At the same time, the set of fittings between the upper (6) and lower (7) of the core (3) and their respective housings (10) and (12) of the housings (1) and (2), is such that It allows fl exo-extensor, lateral and rotational fl exo of the assembled assembly.

From all this, it follows that the cervical prosthesis that is advocated in the present invention has four degrees of freedom from zero of conventional fusion prostheses that stiffen the upper vertebra (14), prosthesis and lower vertebra (15) not allowing any relative movement from one to the other, in addition to the above-mentioned drawbacks of current mobile prostheses.

Once the nature of the present invention is sufficiently described, as well as a practical application thereof, it only remains to be added that, both its form and the materials and execution thereof, are susceptible to modifications, as long as they do not affect Substantial form to the characteristics claimed below.

Claims (5)

1. Flexible cervical prosthesis, for use in surgical interventions with cervical disc removal, characterized in that this prosthesis consists of an upper housing (1) with a threaded outer area

(4)

and which has inside a spheroidal cavity (10), a lower housing (2) also with a threaded outer area (5), lower housing (2) in which a housing or socket (12) is established, defining the cavity spheroid (10) and housing or socket

(12)

a space for receiving a core (3), formed in turn by two parts, an upper (6) and a lower (7) joined together by a heel (9), with the particularity that these threaded bodies (4 , 5) adopt longitudinal notches (8), and where all the pieces of which this prosthesis is composed are completely radio transparent and are provided with housings to locate radio-opaque bodies,

where the mounted prosthesis forms a threaded cylinder.

2.

Flexible cervical prosthesis, according to claim 1, characterized in that the outer surface (11) of the upper part (6) of the core (3) slides over the surface of the spheroid cavity (10) of the upper housing (1), so that these surfaces are congruent, according to movements of fl exion-extension and lateral fl exus.

3.

Flexible cervical prosthesis, according to claim 1, characterized in that the body (7) forms edges in such a way that it allows a limited rotation and translation movement on its seat arranged in the socket (12) of the lower housing (2).

Four.

Flexible cervical prosthesis, according to claim 1, characterized in that the core (3), specifically between its upper part (6) and the lower part (7) defines an opening (16).

SPANISH OFFICE OF THE PATENTS AND BRAND Application no .: 200801226 SPAIN Date of submission of the application: 04.29.2008 Priority Date: REPORT ON THE STATE OF THE TECHNIQUE 51 Int. Cl.: A61F2 / 44 (2006.01) RELEVANT DOCUMENTS

Category

Documents cited Claims Affected

X

WO 0164142 A1 (CAUTHEN RES GROUP INC et al.) 07.09.2001, page 6, line 27 - page 17, 1-4

line 5; Figures 1-19.

X

WO 9953871 A1 (CAUTHEN RESEARCH GROUP INC) 28.10.1999, page 5, 1-4

line 29 - page 13, line 28; Figures 1-13.

TO

US 2007118224 A1 (SHAH GRETCHEN D et al.) 05/24/2007, description; figures. 1-4

TO

US 2005149189 A1 (MOKHTAR MOURAD B et al.) 07.07.2005, description; figures. 1-4

TO

US 6402785 B1 (ZDEBLICK THOMAS A et al.) 06.11.2002, description; figures. 1-4

TO

WO 2008022471 A1 (SYNTHES GMBH et al.) 28.02.2008, description; figures. 1-4

TO

US 2005165485 A1 (TRIEU HAI H) 28.07.2005, description; figures. 1-4

Category of the documents cited X: of particular relevance Y: of particular relevance combined with other / s of the same category A: reflects the state of the art O: refers to unwritten disclosure P: published between the priority date and the date of priority submission of the application E: previous document, but published after the date of submission of the application

This report has been prepared • for all claims • for claims no:

Date of realization of the report 04.24.2011

Examiner E. �? Lvarez Valdés Page 1/4

REPORT OF THE STATE OF THE TECHNIQUE Application number: 200801226 Minimum documentation sought (classification system followed by classification symbols) A61F Electronic databases consulted during the search (name of the database and, if possible, terms of search used) INVENES, EPODOC, WPI State of the Art Report Page 2/4  WRITTEN OPINION Application number: 200801226 Date of Written Opinion: 04.24.2011 Statement

Novelty (Art. 6.1 LP 11/1986)

Claims Claims 1-4 IF NOT

Inventive activity (Art. 8.1 LP11 / 1986)

Claims Claims 1-4 IF NOT

The application is considered to comply with the industrial application requirement. This requirement was evaluated during the formal and technical examination phase of the application (Article 31.2 Law 11/1986).  Opinion Base.- This opinion has been made on the basis of the patent application as published. State of the Art Report Page 3/4  WRITTEN OPINION Application number: 200801226 1. Documents considered.- The documents belonging to the state of the art taken into consideration for the realization of this opinion are listed below.

Document

Publication or Identification Number publication date

D01

WO 0164142 A1 (CAUTHEN RES GROUP INC et al.) 07.09.2001

D02

WO 9953871 A1 (CAUTHEN RESEARCH GROUP INC) 10/28/1999

2. Statement motivated according to articles 29.6 and 29.7 of the Regulations for the execution of Law 11/1986, of March 20, on Patents on novelty and inventive activity; quotes and explanations in support of this statement The invention defined in claim 1 refers to a flexible cervical prosthesis, suitable for use in surgical interventions with removal of the cervical disc, which consists of an upper housing with a threaded outer area and which has a spheroid cavity inside, a lower housing also with a threaded outer zone and in which a housing is established. The spheroid cavity and the housing define a space for receiving a core formed in turn by two parts, an upper and a lower one joined together by a heel. The aforementioned threaded bodies adopt longitudinal notches. The prosthesis forms a threaded cylinder and all the parts that compose it are radiolucent. D01 is considered the prior art document closest to the object of claim 1. Document D01 discloses (references D01) a flexible cervical prosthesis (10), suitable for use in surgical interventions with cervical disc removal ( page 1, lines 14-15), consisting of an upper housing (20) with a threaded outer area (80) and which has a spheroidal cavity (46) inside, a lower housing (22) also with an outer area threaded (80) and in which a housing (82) is established. The spheroid cavity and the housing define a space for receiving a core (90), which in turn consists of two parts, one upper and one lower (46, 48). The aforementioned threaded bodies adopt longitudinal notches (32, 36). The prosthesis forms a threaded cylinder (figures 1A, 1B) and all the parts that compose it are radiolucent (page 7, line 31- page 8, line 1) and are provided with housings (62, 72). The difference between D01 and the first claim is: The upper and lower parts of the core are joined together by a heel. The technical effect associated with this difference is that the heel or throat performs the function of transmitting the loads and undergoing elastic deformations. The function of transmitting the loads and suffering the elastic deformations performed by the said heel, is performed in D01 by the joint (24). Therefore, it would be obvious for a person skilled in the art to apply the characteristics of document D01 and arrive at the invention as disclosed in claim 1. Therefore, the object of this claim meets the requirement of novelty (Art. 6.1 of Patent Law 11/1986), but does not meet the requirement of inventive activity (Art. 8.1 of Patent Law 11/1986). The invention defined in claims 2, 3 and 4, all of which are dependent on the first, refer respectively to the fact that the upper part of the nucleus and the spheroid cavity are congruent, that the lower part of the nucleus forms edges and that the nucleus between its upper and lower part defines an opening. There are no technical effects associated with the differences between D01 and claims 2, 3 and 4, so the aforementioned claims 2, 3 and 4 meet the novelty requirement (Art. 6.1 of Patent Law 11/1986) but no they meet the requirement of inventive activity (Art. 8.1 of Patent Law 11/1986). Document D02 discloses a flexible cervical prosthesis, suitable for use in surgical interventions with removal of the cervical disc, consisting of an upper housing with a threaded outer area and which has a spheroidal cavity inside, a lower housing also with an area threaded exterior and in whose bosom a housing is established. The spheroid cavity and the housing define a space for receiving a nucleus formed in turn by two parts, an upper and a lower one joined together by a heel. The aforementioned threaded bodies adopt longitudinal notches. The prosthesis forms a threaded cylinder and all the parts that compose it are radiolucent and are equipped with housings. It can be said that claims 1 to 4 meet the requirement of novelty (Art. 6.1 of Patent Law 11/1986) but not that of inventive activity (Art. 8.1 of Patent Law 11/1986) in view of the technical characteristics disclosed by document D02. State of the Art Report Page 4/4