DE202004001021U1 - Reduction implant for the reconstruction of a vertebral body - Google Patents

Abstract

A reduction implant 1 for the fixation of e.g. injured vertebral body 2 caused by osteoporosis, which is inserted into an implantation hole 22 cut for its implantation in the vertebral body 2 by means of a tool intended for this, characterized in that the reduction implant 1 has an elongated, tapered shape, the dimensions of which match the implantation hole 22 be, which penetrates from a pedicle 21 of the vertebral body 2 over the length of the pedicle 21 through this and extends deep into the central main part of the vertebral body 2, that the reduction implant 1 at its rear end has a threaded bore 14 with an internal thread for a Has external thread of the tool and is provided with a roughening on its surface 13.

Description

[Technical field]

The invention relates to a reduction implant, that of the pedicle of a vertebral body implanted in it for reconstruction or augmentation is, according to the preamble of claim 1. Particularly suitable the invention for percutaneous vertebroplasty of osteereoporotic vertebral compression fractures and blowout fracture and for the treatment of osteoporosis.

[State of the art]

Osteoporosis is the most common Human bone disease. In Germany e.g. there are three Millions affected and ten million at risk, special ones Women (80% of patients suffering from it). Almost all of the Post-menopausal women more or less suffer from osteoporosis. The same problem also arises in old men. at In osteoporosis, the bones have their calcium content and therefore lost their firmness, and even threaten to break during everyday activities. This risk of fracture is particularly high in the spine.

As risk factors of osteoporosis count the following factors, namely:

• 1) Race: The black ones have a higher density in their bone masses as the white or the yellow race, and thus they suffer less from osteoporosis than the latter.
• 2) Way of life and habits: people with one or more belong to the following habits to the groups at high risk of osteoporosis: Smoking, alcoholism, excessive drinking of tea and coffee, insufficient or excessive exercise.
• 3) Genetic factors: people with a family history of osteoporosis: people with a family history of disease fall a lot more of osteoporosis than those without an osteoporotic family history.
• 4) Pharmaceutical factors: patients with long-term treatment of the following drugs are more likely to develop osteoporosis: steroid, thyroxine, Diuretic, tetracycline, heparin, antieptileptic, lithium salt, Antagonist, aluminum-containing antacid, and patients under chemical Treatment.
• 5) Production of the sex hormone: The female hormone estrogen protects women of childbearing age from bone loss. The function of the ovaries decreases during menopause. Estrogen levels drop and age-related bone loss accelerates. About every third woman after the age of 60 suffers from osteoporosis. But young women can also develop osteoporosis, for example, after removing the ovaries or due to natural or surgical menopause. In men, the male hormone protects testosterone similarly to the female estrogen, but the hormone production declines later and more slowly because they do not have classic menopause. Statistically, women fall ill 6 to 8th times more osteoporosis than men. Especially in women with little body formation or delayed menarche, or in nulliparous or older women.

Depending on the types and directions of bone fixation in the treatment of fractures of vertebral bodies in conventional therapies, a distinction is made between back nail fixation, in which the fixation is done by driving bone nails from behind into a vertebral body, and front implant fixation, in which the fixation is by implanting a Bone implants, for example made of a bone substitute material or a patient's own bone part, are made from the front into a vertebral body. In each of the two conventional osteoporosis therapies, in order to fix a single damaged vertebral body, the two normal vertebral bodies above it on the one hand, and on the other hand the two normal vertebral bodies below it must be subjected to a cutting fixation and thus additional damage. As a result, the fixation of a single vertebral body must be purchased with the loss of mobility of up to five successive vertebral bodies, which leads to a rigid spine which is considerably limited in mobility. It is also disadvantageous in the case of the conventional osteoporosis therapy mentioned above, since a large cavity is left in the vertebral body which actually suffers from osteoporosis after its reduction. If the cavity is not filled (eg with a synthetic or a natural or own bone material) and the support is only provided by the bone nail driven in from behind, the fixation stability is not sufficient at all. Under certain circumstances, unwanted detachment or breakage can occur at the fixation site, which results in unsuccessful surgery. With the last-mentioned conventional therapy, on the other hand, there is a risk that the surgery or implants used from the front to access the vertebral body will have to penetrate through the bosom or abdominal cavity, causing the organs located therein (e.g. the Lungs and blood vessels, the aorta and nerves) can be injured, which is why the operation must be carried out very carefully and is therefore very time-consuming. Infection can also result from the implantation of the bone of a bone donor. In addition, the front implantation fi xation the problem of accepting a stiff and relatively immobile spine remains unsolved.

The invention is therefore the object based on a reduction apparatus for the reconstruction of vertebral bodies create, with the above disadvantages of the prior art in the Vertebral fixation can be avoided.

According to the invention, the object is achieved by a Reduction implant according to claim 1 solved.

The invention is based on the idea to fix a damaged one vertebra during the implant surgery from behind without a simultaneous Fixation of four additional vertebra to need the drilling from a pedicle of the vertebral body through the pedicle through over its length deep into the vertebral body. Then an implant is inserted into the resulting hole. So that the tissues are close not through the implantation tool during implantation of the implant in the vertebral body can be injured, it must The smallest possible radial dimension at the front end of the tool and do not carry any dangerous radially protruding parts. To meet this requirement must the Holder of the implant to be implanted at the front end of the Tool done by that Implant has a threaded hole at its rear end, while the tool accordingly has a complementary thread at its front end Has. When implanting, the implant is first placed on the front Screwed end of the tool and stabilized on it. After Implanting the implant into the hole is the tool of Implant loosened and pulled out of the hole. Now the hole made by outside free accessible remains, with a bone-forming material (e.g. with a synthetic or natural or own bone material) can be precipitated.

The advantage of drilling one pedicle (in 2 with reference numerals 21 referred to) in a vertebral body of the same rather than a direct drilling into its main proximal part (in 2 With 2 consists in the fact that, thanks to the extended distance of the reduction implant through the entire bore penetrating through its entire bore, a reduction implant receives an extended and premature guidance and thus a centering before it penetrates into the proximal main part of the vertebral body, thereby considerably stabilizing the implantation of the reduction implant and is relieved.

To an augmentation / spreading effect during its Insertion in the vertebral body to achieve, the implant has a wedge-shaped, tapered design on, whereby the bone mass through the radial expansion of the Implant during its insertion compressed and compacted, resulting in increased stabilization of the implant in the hole.

To prevent it from slipping out and falling the implant out of the hole during or after removing the tool, this will on its surface roughened, resulting in an increased Force or friction between the implant and the inner wall of the hole.

The invention is described below a preferred embodiment explained in more detail. It demonstrate:

[Drawing]

1 a reduction implant according to the invention in perspective view,

2 in longitudinal section a part of a spine with a reduction implant according to the invention implanted in its one vertebral body, and

3 as in 2 the part of a spine with a reduction implant according to the invention and an additional fixation with two bone nails.

[Explanation of the Preferred Embodiment]

1 illustrates a reduction implant according to the invention 1 which has a curved wedge shape tapering forward at its front end with a smaller front end 11 and a larger rear end 12 which tapers after the opposite end. The reduction implant 1 is on its surface 13 slightly arched and provided with a roughening from numerous distributed fine-grained elevations, and has at its rear end 12 a threaded hole worked into it 14 with an internal thread for a specific implantation tool (not shown in more detail) that at its front end with the internal thread 14 cooperating eye thread.

When implanting the reduction implant 1 in a vertebral body 2 is first in the pedicle 21 of the vertebral body 2 an implantation hole 22 (eg using a bone drill). Then the reduction implant to be implanted 1 stabilized with its threaded hole at the front end of the implantation tool and with the help of the same in the implantation hole 22 pushed in, causing some augmentation / spreading of the implantation hole 22 causes and thus the reduction implant is clamped in it by the compacted bone mass. Now the tool can be removed from the reduction implant 1 loosened and pulled out. After removal of the tool, they cannot pass through the implant 1 occupied volume of the bore 22 with a bone material, such as a body's own bone mass or egg bone replacement material. As a result, the reduction implant is made on the one hand by the design 1 safe in the vertebral body 2 embedded and on the other hand the swelling of the vertebral body 2 fixed as a result of the drilling.

The profile of the elongated reduction implant 1 will depend on the anatomical shape of the pedicle 21 matched, which has a longitudinal section that has a shape between a rectangle and an ellipse, and a cross section with a slightly bulging square shape. Because the diameter of a pedicle 21 around 50–60% of the height of the vertebral body 2 (please refer 2 ), this can be caused by that of the pedicle 1 implanted reduction implant 2 be repositioned at least up to 50-60%. With the 50–60% partial repositioning it can interact with the rest of the vertebral body 2 an overall reduction of 70-80% can be achieved.

In this way, sufficient fixation of an injured vertebral body can certainly be achieved 2 take place without requiring a cutting or other similar injuring step (e.g. drilling or driving in bone nails or screwing in bone screws) on the adjacent, healthy vertebral bodies. In order to further increase the stability of the fixation, the spine can be placed directly above the injured vertebral body 1 lying and on his immediately above the injured vertebral body 1 lying uninjured vertebral body with an aid fixation 3 be provided like it 3 evident.

The invention has over State of the art has the following advantages:

• 1) Because access to the injured vertebral body and the fixation on the posterior side of the pedicle takes place, the risk of injury to the organs in the breast or abdominal cavity (as is the case with a frontal implantation) avoided.
• 2) Because of the opposite the state of the art very much increased stability as a result the extended guide The hole in the pedicle can be attached to the additional fixation on the four healthy vertebral bodies be dispensed with, thereby reducing the negative effect of fixation on the Spine mobility is kept to a minimum.
• 3) The roughened surface of the reduction implant increases its positional stability and other carries for ingrowth of bone tissue.

Claims (1)

A reduction implant 1 for the fixation of an injured vertebral body caused, for example, by osteoporosis 2 that in a for its implantation in the vertebral body 2 incised implant hole 22 is introduced by means of a tool intended for this, characterized in that the reduction implant 1 has an elongated, tapered shape, the dimensions of which are on the implantation hole 22 be matched by a pedicle 21 of the vertebral body 2 out over the length of the pedicle 21 penetrates through this and deep into the central main part of the vertebral body 2 extends that the reduction implant 1 a threaded hole at its rear end 14 with an internal thread for an external thread of the tool and on its surface 13 is provided with a roughening.