FR2794967A1 - Dilating device for insertion in bone joints, useful for joints affected by degenerative tissue disease, is shaped like a cone designed to fill the biconcave joint cavity - Google Patents

Abstract

Dilation and interposition device (A) for restoring the distance and relative angular positions between two articulated, concave bone surfaces that have suffered deformation, displacement of closure as the result of degeneration of the tissue in the joint. The device is cone shaped along its long axis and the smallest end (3), the introduction end, is designed to penetrate, without effort, the space between the two bone surfaces. The cone increases in size progressively towards a central region (4), that has a diameter corresponding to the articular space to be restored, then it becomes smaller towards the other end (5), but is never less than 1/3 of the diameter of (4). The different sizes of (3) and (5) creates a mean inclination of the articular surfaces, and this inclination can be varied by appropriate choice of the ratio between length, height of (4) and height of (5).

Description

The present invention relates to a dilating warhead (I) intended to restore the distance (20) and the angular position (21) respectively between concave articular bone surfaces (10) and (11) having undergone a deformation, a tilt and! or a bringing together by a degenerative process of the articular interposition tissue. Said warhead (1) is designed for easy penetration into the narrowed space (12), by means of a spiral groove (2) starting from its insertion end (3) and flaring towards its swollen zone (4) to ensure the spreading and translational movements simultaneously. The ogival shape adapts to the concavity of the articular surfaces (10) and (11) and its angulation foreshadows the final angular bone position (21).

Degenerative joint pathologies, whether of post-traumatic, rheumatoid or arthritic origin, result in wear and / or pinching of the interposition tissues located between the mobile bone surfaces. These deteriorations cause the formation of peri-articular osteophytes increasing the tension of the ligaments; This in turn contributes to the closure of the inter-bone space (joint pinching), the reduction of mobility and pain in load or during movements.

There are various systems intended to treat degenerative articular pathologies, namely - The vertebral implant (PCTlCH96 / 00127), being in the form of a hollow, cylindrical elongated body, filled with bone substitute material; - The implant for intervertebral disc (PCT / US96 / 03226), in the form of a cylindrical body, the exterior of which has a helical thread; - The vertebral intersomatic arthrodesis prosthesis (F 95 14655), in the form of a cage inscribed in a surface of revolution, having a thread, and a central recess open on the sides, so as to be able to receive a bone graft and allow bone fusion; - The apparatus intended to merge adjacent bone structures (PCT / US97 / 18998), being in the form of a longitudinal part of generally elliptical dimensions in cross section.

To summarize, current treatments call for - Either arthrodesis, the purpose of which is to fix the bones of the joint in a position of indolence, then to create the conditions for a bony weld, obtained by their sharpening, often associated with grafts and / or filling materials.

- Either joint prostheses intended to replace the bone interposing material with artificial surfaces having a sliding or damping role.

The two methods make it possible to restore space or angular mobility as appropriate, but with difficulty both at the same time.

In addition, the concave articular surfaces achieve a hollow shape which is difficult to treat with a joint prosthesis. The embodiment usually chosen is the interposition of a generally spherical or lenticular piece introduced between the bearing surfaces fixed respectively in the adjacent bones. However, the stability of this room is very questionable and cases of eviction have been noted.

The subject of the present invention {fig. I} is to achieve the stability of at least two bones each having a concave articular surface (10) and (11) opposite, by at least one interposition element of ogival shape (1), according to its longitudinal dimension, the smallest end of which, called the introductory end (3), is designed to effortlessly penetrate the joint space. Said form of revolution has a progressive bulge up to its central zone (4) whose dimension corresponds to the height of the articular space (12) to be restored, then tapers substantially at its opposite end (5) at the end of introduction (3), without however being less than 1I3 of the dimension of the central zone (4).

Said shape of ogival longitudinal revolution having its insertion end (3) smaller than the opposite end (5) creates an average inclination of the articular surfaces (10) and (11) which it is possible to vary by choosing the relationship between the length, the height of the central zone (4) and the height of the opposite end (5).

The placement of one or more warheads (1) requires an ablation of the osteophytes at least around the insertion area to release the length, therefore the ligament tension. The height and length of the warhead (1) are determined. The selected warhead (1) is assembled on an instrument (7) making it possible to exert a thrust and / or a rotation, in order to obtain the dilating effect and its penetration in the biconcave space (12) previously cleaned. To do this, the opposite end (5) to the insertion end (3) is preferably provided with means (6) for holding and / or driving in rotation.

Although penetration into the biconcave space (12) can most often be achieved by a simple push, the present invention {fig. II} incorporates into its surface of revolution a spiral groove (2) starting from its insertion end (3), flaring towards the swollen central zone (4), the aim of which is to obtain easy penetration by rotation thanks to the ripple effect it achieves.

In order to respect the articular bone (10) and (I 1), said warhead (1) is blunt so as not to present any aggressive sharp angle.

According to one embodiment {fig. III}, the warhead (1) can be hollowed out (8) in its longitudinal direction and perforated radially (9) in the bottom of the spiral groove (2) to allow the passage of an osteo-inducing material such as, for example for example, autogenous bone or morphogenic bone proteins (BMP), or osteoconductive such as, for example, compounds based on tricalcium phosphate (TCP) or hydroxyapathite (HA).

Claims (5)

1) Expansion and interposition means (1) intended to restore the distance (20) and the respective angular position (21) between concave articular bone surfaces (10) and (11) having undergone a deformation, a tilt and / or a bringing together by a degenerative process of the articular interposition tissue, in the shape of an ogival revolution according to its longitudinal dimension, the most reduced end of which, called the introduction end (3), is designed to effortlessly penetrate the joint space . Said form of revolution has a progressive bulge up to its central zone (4) whose diameter corresponds to the height of the articular space (12) to be restored, then tapers substantially at its opposite end (5) at the end introduction (3), without however being less than 1/3 of the central diameter. Said insertion end (3) being smaller than the opposite end (5), an average inclination of the articular surfaces (10) and (11) is created which it is possible to vary by choosing the ratio between the length , the height of the central zone (4) and the height of the opposite end (5). 2) Expansion and interposition means according to claim 1, characterized in that it incorporates on its surface of revolution a spiral groove (2) starting from its insertion end (3), widening towards the area swollen central unit (4), the aim of which is to obtain, during separation, easy penetration by rotation thanks to the ripple effect which it achieves. 3) Expansion and interposition means according to claim 1 or 2, characterized in that the opposite end (5) to the insertion end (3) is preferably provided with a holding means and / or rotary drive (6) into which is introduced an instrument (7) for exerting a thrust and / or rotation, in order to obtain the dilating effect. 4) Expansion and interposing means according to any one of the preceding claims, characterized in that said warhead (1) is blunt so as to have no aggressive sharp angle, in order to respect the articular bone (10) and (11 ). 5) Expansion and interposing means according to any one of the preceding claims, characterized in that the warhead (1) is hollowed out (8) in its longitudinal direction and radially perforated (9) in the bottom of the groove spiral (2) to allow the passage of an osteo-inducing material such as, for example, autogenous bone or bone morphogenic proteins (BMP), or osteo-conductive like, for example, the compounds based tricalcium phosphate (TCP) or hydroxyapathite (HA).