WO2014098779A2

WO2014098779A2 - Artificial ligament and tendon repair system

Info

Publication number: WO2014098779A2
Application number: PCT/TR2013/000371
Authority: WO
Inventors: Mustafa Cemil ALLAHVERDI; İrfan ISIK; Mehmet Hakan AKPINAR; Sevki Serkan HEZAR; Mahir MAHIROGULLARI
Original assignee: DEMIRBOGA, Muhittin
Priority date: 2012-12-21
Filing date: 2013-12-20
Publication date: 2014-06-26
Also published as: WO2014098779A3; WO2014098779A4

Abstract

The present invention relates to a prosthetic ligament and tendon repair system made of nitinol and titanium materials and developed for use in all kinds of joints.

Description

DESCRIPTION

ARTIFICIAL LIGAMENT AND TENDON REPAIR SYSTEM

Field of the Invention

Background of the Invention

The knee is a joint in the form of a hinge disposed between the thigh bone (femur) and the shin bone (tibia) . The joint comprises two parts, i.e. the inner and the outer parts. Said joint is protected by the knee cap in the front part thereof. All the bone surfaces within the joint are covered with the joint cartilage.

Ligaments are structures securing the knee joint. The ligaments, which are completely different structures, should not be confused with the tendons. Ligaments are fixed structures, both ends of which are attached to the bones and they are provided with limited flexibility. On the other hand, tendons are structures with one end thereof being attached to the bones, while the other end thereof continues with the muscles and transmits the motion of said muscles to the bones.

Lateral ligaments are provided on the inner and outer sides of the knee and prevent the knee from opening to both sides. Apart from the outer lateral ligaments, ligaments preventing the knee from opening to outside are provided on the rear outer corner of the knee. Anterior cruciate ligament (ACL) connects the tibia and femur to each other exactly through the middle point. The function thereof is to limit the rotational motion of the knee and to prevent the forward movement of the tibia. Posterior cruciate ligament (PCL) prevents the backward movement of the tibia.

The anterior cruciate ligaments consist of rigid and inflexible fibers and aid in stabilizing the knee by preventing excessive forward movement and rotation of the tibia on the femur. Said ligament restrict the forward, inward and outward rotation of the tibia bone. It extends inside the knee from back to front, and from outside to inside in the midline thereof. ACL tears mostly occur during sudden change of direction (football, tennis, skiing) and sudden deceleration while descending to the ground during jumping or running .

The anterior cruciate ligament (ACL) can be damaged by various mechanisms; however, said damage often occurs during rotation or falling on the knee. Turning of the leg onto itself and falling to the ground upon sticking the foot to the artificial turf in the astro pitch, likewise, falling during skiing and turning of the body on the fixed leg due to the ski remaining in place lead to ACL tears. Unfortunately, this important anatomic structure does not heal by itself and operation is needed to confer the functions thereof again. In the operation, own parts of the ligament cannot be used.

Since the anterior cruciate ligament tears rather occur as a result of the sport injuries, there is quite a large group of patients and anterior cruciate ligament reconstruction is widely carried out all over the world. There are several different methods widely used for reconstruction of the anterior cruciate ligament:

Among these methods, the best known involve connecting the tendon or the ligament to the bone by means of metal or dissolvable materials. Moreover, for some ligaments and tendons, the firm ligaments and tendons present in various parts of the patient are taken and can be connected to the damaged regions by means of metal or dissolvable materials. Particularly, in the treatment of anterior cruciate ligament, carrying out the reconstruction by placing a new ligament instead of the tendon, repair chance of which is almost zero, is the most widely used treatment method. In this context, a tissue having similar rigidity, structure, and length to that of the ACL taken around the knee is transferred to the original position of the ACL. For this operation, 5 types of tissue grafts are used;

1. Patellar tendon: The middle 1/3 of the patellar tendon extending between the knee cap bone and the tibia are taken together with the bone fragments having a size of 1 x 2 x 1 cm (length of 2 cm, width and height of 1 cm) on the upper and lower part.

2. Rear knee tendons: The hamstring tendons located on inner rear part of the knee are taken and folded to the appropriate length and thickness. These two tissues are used 90% of the time .

3. Quadriceps tendon: The tendon located on the knee cap is taken therefrom along with a bone fragment having a size of 2 x 1 x 1 cm.

4. Allograft: Tissues taken from cadavers are used. 5. Synthetic ligaments: They are rarely preferred due to the complications thereof. In the future, thriving synthetic ligaments can be developed.

These tissues are taken by open surgery. To do this, small incisions of about 3- 4 cm are used. Then, the ACL residues remaining in the knee are arthroscopically cleaned (in advanced centers) and 2 tunnels are formed in the tibia and femur bones matching the original ACL locations. The taken tissue is placed into said tunnels and fixed thereto by means of proper tension materials such as screws, wires and nails. A knee brace is generally applied after surgery.

While, as has been shown, it is possible to carry out repair by taking the graft from the patient himself/herself, this leads to the weakening of the area where the graft is taken. In other words, the patient will not be able to use these muscles as the tendons thereof are removed. Also, the events such as tendon ruptures that may occur when said tendons are taken from the patient can bring an additional morbidity to the patient.

The allografts of human origin used in the arthroscopic repair of the anterior cruciate ligament comprise two types as fresh frozen and dried. The allografts of human origin stored as dried are softened in a saline solution for a certain period of time prior to surgery, while the fresh frozen allografts are made ready for use by being kept at room temperature. The product made ready for use can be connected to the patient by means of repair materials available in the market. However, the reliability of allografts of human origin is controversial. Although tests are performed against the known diseases, allografts of human origin can carry diseases being present in the person from whom said allografts are taken. In addition, the ages of the people . from whom said allografts are taken are not known. Therefore, placement of grafts belonging to elderly people to the younger patients can be the case especially in the ligament and tendon repairs. The allografts of elderly people give rise to quick dissolution and ruptures in younger patients and the performed surgical operation fails.

The second method of reconstruction of the anterior cruciate ligament is the placement, during treatment, of a relatively small number of autograft products made of synthetic (polyester) materials into the body of the patient by means of using fasteners such as screws, buttons or pins comprised of metal or dissolvable materials.

In the prior art, the U.S. patent application numbered US2009054982 and titled 'Elastic metallic replacement ligament' states the following: 'The present invention relates to the orthopedic implants for reconstruction of severed, ruptured, or damaged ligaments. More particularly, this invention relates to an improved elastic replacement ligament made from metallic wires in a braided construction for replacement of a natural ligament of the body such as the anterior cruciate ligament of the knee.'

In said patent, the use of metal tubes causes the wear of said replacement attached to the bone. This shortens the service life of the replacement. On the other hand, said wear disrupts the comfort and can restrict the movement. In the prior art, the U.S. patent application numbered US2003114929 and titled 'Prosthetic ligament' states the following: Ά prosthetic ligament includes a cord of thermotropic liquid crystal filaments. The cord preferably comprises multi-filament thermotropic liquid crystal filaments. The cord has an eye spliced at each of its ends.'

Here, some difficulties may be encountered during placement and attachment process of said prosthesis to the bone. The reason for this is the use of screw like apparatuses during the prosthesis placement process, because the screws placed in the soft tissue of the bone wears said bone and they cannot be held inside the bone after a period of time.

The attachment methods, whether autograft or allograft, may include difficulties regarding the implementation techniques, as well as side effects. In a so called button connection method, a metal button and a polyester conveying band are used. This system can lead to tunnel expansion by providing a suspension effect. The suspension system referred to as cross pinning requires an additional surgical procedure and causes frequent difficulty in practice with respect to the other systems. In the screw connections, problems such as bone tunnel wall fracture inside the joint due to the screws and falling of the screws into the joint can occur.

In addition, the previous techniques suffer from problems such as construction of the used materials from those causing them to elongate more than the actual biological sample or utilization of connection methods causing excessive elongation thereof. When the material used elongates excessively, patient's movement is restricted by the deterioration of the synchronization between muscles . and bones .

On the other hand, in the surgical procedures carried out with allografts by taking pieces from the other tissues around the knee joint, the movement of said knee joint. is also undermined by weakening of the other tendons and ligaments enabling healthy movement of the knee.

In addition, the recovery time of the treatment increases due to the formation of a plurality of scars and stitches in the event that the allografts performed by taking pieces from other tendons and ligaments are used. The duration of the surgery can last 1.5 hours or more. In this case, the patient is taken away from his/her normal life for a longer period of time, and healing duration of the wound also increases. For example, the patients are allowed to run smoothly or to ride a bike approximately after 3 months. Sportive activity is resumed within 4-6 months.

On the other hand, the metallic materials used are sometimes unable to biologically adapt to human tissues; thus, various infections can be seen. In the use of synthetic products for the reconstruction of the anterior cruciate ligament, rejection reactions can take place in the body against the synthetic product, problems such as swelling, persistent pain in the knee can occur, and the antibodies formed in the body partially weaken the synthetic material. Also, the synthetic materials wear the edges of the bone over time by acting as a sharp line inside the knee and can cause expansion in the bone tunnels. Thus, the usage area thereof is limited. Objects of the Invention

The present invention is developed for the purpose of aiding the surgical interventions performed as a result of the physical injuries and ruptures occurring in the anterior cruciate ligament and all the other tendons and ligaments.

Another object of the present invention is to put an end to the inconveniences of the person caused by the treatment procedures performed by taking pieces from the patient's other ligaments, tendons or muscles.

Another object of the present invention is to reduce the long treatment and surgical operation durations. In this system, the surgical operation duration is at most 30 minutes.

Another object of the present invention is to prevent the friction arising from the metallic structure of the prosthetic materials placed from outside and thus, the bone wears resulting therefrom.

Still another object of the present invention is to construct tendon and ligament prostheses that are fully compatible biologically. They can be used even in patients who are allergic to nickel. Another object of the. present invention is to enable enough elongation and . shape change of the placed prosthesis in accordance with the original biological sample.

Another object of the present . invention is to provide a secured and durable placement of the prosthesis inside the bone.

Another object of the present invention is to provide solutions for the tunnel expansion and wear problems that will occur after the treatment, as well as to prevent the suspension movement of the tendon.

Also, another object of the present invention is to obtain a prosthesis that is more durable and stronger than the normal anterior cruciate ligament.

Description of the Figures

Figure 1. Top view of the ligament and tendon repair system Figure 2. Side view of the ligament and tendon repair system Figure 3. Peg structure of the ligament and tendon system

The parts shown in the figures mentioned above are individually numbered, wherein part names corresponding to these numbers are given below:

1. Double cylinder tube 1.1. Tube segment

1.2. Articulation line

2. Metal wires

3. Femoral button ring 3.1. Femoral peg

4. Tibial screw hole

5. Teflon coated strips 5.1. Teflon holes

Description of the Invention

The present invention relates to a braided type prosthetic ligament and tendon repair system made of a titanium-nitinol material and comprising the following: a special femoral button ring (3) provided at one end thereof for placement of the femoral peg (3.1) positioned parallel to the extension direction of the tube; a tibial screw hole (4) provided at the other end thereof and positioned again parallel to the extension direction of the tube; a flattened double cylinder tube (1) made of flexible metal wire (2) material, formed in special molds by joining at least two ceramic coated tube segments (1.1) with same length and different^' radius by an articulation line (1.2); and teflon coated strips (5) positioned on both ends of said cylinder tube so as to be perforated and provided with special teflon holes (5.1) perforated thereon with a certain spacing.

The system, in order to achieve maximum efficiency and maximum strength, is especially provided in the form of an articulated two segment double cylinder tube (1) . However, the number of segments can also be more than two.

The structure is obtained by braiding of the ceramic coated metal wires (2) so as to form a helix in the special molds. The femoral button ring (3), tibial screw hole (4) are not post formed on the prosthetic cylinder and they are integrally obtained inside the special molds that are suitable for this form.

The prosthesis is made of ceramic coated materials in order to achieve better bone compatibility. Ceramic is known to be a material with relatively high bone compatibility, and thus undesirable complications and reactions are not observed in the joints. Indeed, ceramic can be used in the hip prostheses.

The coefficient of friction increases in the event that the placed prosthetic materials are made of metallic materials and bone wear takes place. Over time, said wears can lead to movement problems and pain resulting from wear. For this reason, the coefficient of friction is reduced by coating the system with ceramic, and wear caused thereby is prevented.

The teflon coating of the perforatable strips minimizes the amount of damage to the femoral and tibial tunnels and can easily be used for all patients without causing any allergic reaction. Another reason for choosing teflon coated material in this system is that the teflon coated materials are already being used in making synthetic veins and they are fully compatible with the human body. Teflon holes (5.1) are perforated on . the teflon coated strips (5) with a certain spacing, wherein the purpose of said holes is to enable compatibility of the prosthesis placed inside the bone with the body in an easier manner. During the placement of the prosthesis inside the bone, the bone marrow flows onto the prosthesis and the fusion of the prosthesis with the body is provided in a shorter period of time by entry of the bone marrow through said holes.

The used metallic braided cylindrical tubes are made of nitinol material for being in full compliance with the human body and for being used safely in patients who are allergic to nickel material. The stents made of nitinol material are now widely used and known to be in full compliance with the human body.

The ligament and tendon prosthesis according to the present invention is comprised of 2 to 500 flexible metal wires (2) having a thickness of 0 to 1 mm and it is implemented by means of minimally invasive surgical procedure thanks to the provision thereof with a thinner but stronger structure than the original tendon. Thus, tunnel expansion and the tunnel mouth opening problems are not experienced. On the other hand, since the prosthesis can be directly attached to the bone through both ends thereof, it also provides a solution to the suspension movement problem.

In addition, the prosthetic material is attached at an angle by being rotated around its own axis and serves as the anterior cruciate ligament. Accordingly, it is made of a flexible and shapeable material.. However, it is provided with strength sufficient for preventing the elongation thereof against the force, it stretches just until the actual anterior cruciate ligament and the length thereof does not increase. In spite of this, it is much stronger than the actual anterior cruciate ligament and it can withstand up to 1160 Nm of force.

When the prosthesis advances inside the tunnel, the femoral peg (3.1) attached to the femoral button ring (3) takes direction so as to be parallel with the movement direction and facilitates the advancement of the prosthesis inside the bored narrow tunnel. When the prosthesis exits out the bone, it is released as a result of the applied force, takes a vertical position relative to the tunnel and prevents displacement of the prosthesis by being secured. Thus, the physician implementing the prosthesis is not required to perform pulling and suspension movements for placement and reinforcement of the prosthesis, and the system provides convenience for both the physician and the patient.

Said femoral peg (3.1) is connected by means of flexible metal wires (2), which are the continuation of the body, to the femoral button ring (3) .

The present invention can be used not only for the reconstruction of the anterior cruciate ligament, but also for all the other tendons and ligaments and it can provide so many options in terms of usage extensiveness .

Claims

A prosthetic ligament and tendon repair system made_, of a titanium-nitinol material, characterized in that it comprises the following: a special femoral button ring (3) provided at one end thereof for placement of the femoral peg (3.1) positioned parallel to the extension direction of the tube; a tibial screw hole (4), through which a tibial fixation screw is passed, provided at the other end thereof and positioned again parallel to the extension direction of the tube; a flat and flexible metallic double cylinder tube (1) formed in special molds by joining at least two ceramic coated tube segments (1.1) with same length and different radius by an articulation line (1.2); and teflon coated strips (5) positioned on both ends of said cylinder tube so as to be perforated and provided with special teflon holes (5.1) perforated thereon with a certain spacing.

The ligament and tendon repair system prosthesis according to claim 1, characterized in that the cylindrical tube forming the prosthesis can comprise two or more segments.

The ligament and tendon repair system according to claim 1, characterized in that it comprises 2 to 500 flexible metal wires (2) having a thickness of 0 to 1 mm.

The teflon coated strips (5) according to claim 1, characterized in that they are fixed to the body by being connected to the femoral button ring (3) and the tibial screw hole (4) .

The femoral peg (3.1) according to claim 1, characterized in that it is fixed to the femoral button ring (3) by means of the flexible metal wires (2), which are continuation of the body.