MEDICAL DEVICE FOR TENSIONING OF LIGAMENTS ADJUSTABLE TO DIFFERENT ANATOMICAL LOCATIONS

Abstract

The present invention refers to a medical device for tensioning grafts in orthopedic reconstruction of ligaments comprising two subsets: the force applicator subset and the adapter subset. The first subset comprises two identical and symmetrical side arms and uses a helical spring system with a brake to quantify the tensile force. Each side arm comprises a rack (9) linked with a helical compression spring (4), a guiding axle (1), a suture wire securing part (8) and an outer chute (10) in which the rack (9) slides. The adapter subset has a “U” shape and comprises an alignment cone (17) which engages in the graft housing tunnel for controlling the direction of the traction force, and a fixation system composed of an adapter (16), by spikes (19) to be adjustable to the anatomical region and to promote a stable fixation.

Claims

1. Medical device for tensioning of ligaments, adjustable to different anatomical locations, characterized in that it comprises: a) a force applicator subset, with two side arms, consisting of the following components: i. guiding axle (1); ii. screw-nut (2); iii. bushing (3); iv. helical compression spring (4); v. threaded calibration bushing (5); vi. ball-receiving screw (6); vii. ball-head screw (7); viii. suture wire securing part (8); ix. rack (9); x. chute (10); xi. micro-spring (11); xii. brake lever (12); xiii. elastic pin (13); xiv. handle (14); xv. round head pin (22); xvi. spherical end spring screw (23); xvii. retaining ring (24); b) an adapter subset with a “U” shape, consisting of the following components: xxiii. connecting piece (15); xix. adapter (16); xx. alignment cone (17); xxi. dowels (18); xxii. spikes (19); xxiii. cylindrical pins (20); xxiv. coupling pins (21).

2. Medical device according to claim 1, characterized by comprising a spring system in each arm of the force applicator subset, being the helical compression spring (4) connected to the guiding axle (1) by the bushing(3), and connected to the rack (9) by the threaded calibration bushing (5).

3. Medical device according to claim 1, characterized by comprising a toothed unidirectional brake mechanism composed by a rack (9) and a brake lever (12) connected to the chute (10) by the elastic pin (13).

4. Medical device according to claim 1, characterized by comprising a force applicator subset containing a scale on the guiding axle (1) for reading the value of the applied force to the graft.

5. Medical device according to claim 1, characterized by comprising a suture wire securing part (8), composed of a suture wire securing part (8), connected to the ball-head screw (7), which in turn attaches to the ball-receiving screw (6).

6. Medical device according to claim 1, characterized in that the adapter subset comprises a coupling system to the force applicator subset, composed of the coupling pins (21) that connect the connecting piece (15) to the chute (10), and by the spherical spring screws in contact with the coupling pins (21).

7. Medical device according to claim 1, characterized in that the adapter (16) has a variable anatomical configuration according to the anatomical area of application.

8. Medical device according to claim 1, characterized in that the adapter (16) is connected to the connecting piece (15) through the cylindrical pins (20).

9. Medical device according to claim 1, characterized by comprising a fixing system with two fixing options.

10. Medical device according to claim 9, characterized in that the fixing system is composed of dowels (18) passing through the holes of the adapter (16).

11. Medical device according to claim 9, wherein the fixing system is composed of spikes (19) fitted in the adapter (16).

12. Medical device according to claims 11, characterized by having an elastic strap.

13. Medical device according to claim 1, characterized by having an alignment cone (17) fitted in the graft housing tunnel.

14. Medical device according to claim 1, characterized by having an alignment cone (17) connected to the adapter (16).

15. The use of the medical device defined in claim 1, characterized by comprising the following steps: a) The adapter subset is settled on the surface of the required anatomical region, by leaning the ends of the spikes (19) to the bone and inserting the alignment cone (17) into the graft housing tunnel; b) The adapter subset is secured to the anatomical region using one of the fixing options defined in claims 9, 10, 11 and 12, using dowels (18) or spikes (19); c) The alignment cone (17) is removed from the adapter (16) through a rotational movement; d) The force applicator subset is coupled to the adapter subset, fitting the chutes (10) in the coupling pins (21); e) The spherical spring screws are fastened with the coupling between the two subsets; f) The suture wires of the graft are placed in the suture wire securing parts (8); g) Graft tensioning is performed by applying a force on the handle (14) which in turn is transmitted to the graft through the helical compression springs (4); h) The value of the tensile force is read on the scale of the guiding axle (1); i) The brake mechanism is powered by the micro-spring (11) which causes a rotation of the brake lever (12) that gets in contact with the rack (9); j) The handle (14) rotates about the round head pin (22) to give passage to the surgical auxiliary tools; k) After fixation of the graft to the bone, the medical device is removed from the anatomical region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0028] FIG. 1 shows the device in exploded view, identifying the constituents of the force applicator subset and the adapter subset.

[0029] FIG. 2 presents the two subsets of the device, the force applicator subset and the adapter subset.

[0030] In FIG. 3 one of the side arms of the device is shown, being the other arm symmetrical to this one, and the helical compression spring (4) mechanism of the force applicator subset. A guiding axle (1) is placed inside the helical compression spring (4). At one end where the axle is threaded, a screw-nut (2) and a bushing (3) contact the helical compression spring (4). At the other end, the axle is connected to a threaded calibration bushing (5), which functions integrally with the ball-receiving screw (6) and the ball-head screw (7). When a force is applied by the user, the threaded calibration bushing (5) slides on the guiding axle (1), compressing the helical compression spring (4) against the extremity where the screw-nut (2) stands. The helical compression spring (4) is confined between the screw-nut (2) and the threaded calibration bushing (5), which in turn is limited by a retaining ring (24). The suture wire securing part (8) functions integrally with the guiding axle (1). The suture wire securing part (8) has two rollers where the user clamps the wire sutures manually.

[0031] In each of the side arms of the device, the spring mechanism is connected through a sawed or toothed piece also called a rack (9) to the braking mechanism (FIG. 4). The brake is constituted by the rack (9), the brake lever (12), an elastic pin (13), the micro-spring (11) and the chute (10). The brake lever (12) has two positions, one of which allows the rack (9) to move and the other prevents its movement by engaging one of the teeth. The brake lever (12) has at one end a tooth for engaging into the rack (9) and at the other end a micro-spring (11) is positioned which allows the brake lever (12) to return to the resting position.

[0032] The elastic pin (13) acts as the center of rotation of the brake lever (12) and allows the connection between the rack (9) and the chute (10).

[0033] FIG. 5 shows the handle (14) rotation mechanism. The handle (14) is attached to the rack (9) through a round head pin (22).

[0034] In FIG. 6 the adapter subset is schematized. The adapter (16) has four through holes, which allow the passage of four dowels (18) of variable length, which is predefined by the user. The adapter (16) also has two blind holes where the spikes (19) are mounted.

[0035] FIG. 7 presents the scheme of the connection of the adapter subset to the force applicator subset through the connecting piece (15), and the coupling pin (21) in the chute (10) of the force applicator subset, both by fitting. In order to sustain the relative movement between the force applicator subset and the adapter subset, a spherical end spring screw (23) is placed which immobilizes the coupling pin (21) within the chute (10).

DESCRIPTION OF THE FIGURES

[0036] FIG. 1 shows the entire device in exploded view. In the force applicator subset, the following components are shown: guiding axle (1); screw-nut (2); bushing (3); helical compression spring (4); threaded calibration bushing (5); (6) ball-receiving screw (6); ball-head screw (7); suture wire securing part (8); rack (9); chute (10); micro-spring (11); brake lever (12); elastic pin (13); handle (14); round head pin (22); spherical end spring screw (23) and retaining ring (24). In the adapter subset, the following components are shown: connecting piece (15); adapter (16); alignment cone (17); dowels (18); spikes (19); cylindrical pins (20) and coupling pins (21).

[0037] FIG. 2 shows the two subsets of the device, the force applicator subset and the adapter subset. The first subset comprises two identical, symmetrical side arms and uses a spring brake system to quantify the tensile force modulus. Each side arm comprises a rack (9) linked with a helical compression spring (4), a guiding axle (1), a suture wires securing part (8) and an outer chute (10) in which the rack (9) slides. In order to maintain the applied force, the brake uses the brake lever (12), an elastic pin (13) and a chute (10). The U-shaped adapter subset comprises an alignment cone (17) which engages in the graft housing tunnel for controlling the direction of the tensile force, and a fixation system composed of an adapter (16), by dowels and spikes (19) to adapt to the anatomical region and to promote a stable fixation during the stage of cyclic tests and at the final stage of graft fixation.

[0038] FIG. 3 presents the spring mechanism as well as the suture securing mechanism comprising a guiding axle (1), a screw-nut (2) and a bushing (3) of the helical compression spring (4). The other extremity of the guiding axle (1) is supported by a threaded calibration bushing (5) which is connected to a ball-receiving screw (6) and a ball-head screw (7). There are also shown in FIG. 3 the suture wires securing part (8) and the rack (9).

[0039] FIG. 4 displays the brake mechanism formed by a toothed or sawed piece, also referred as a rack (9), a chute (10), a micro-spring (11), a brake lever (12) and an elastic pin (13).

[0040] FIG. 5 exhibits the mechanism of rotation of the handle (14). The handle (14) is connected to the rack (9) through a round head pin (22). It is possible to observe the distance between the helical compression springs (4).

[0041] FIG. 6 shows the adapter (16) having four through holes, which allow to pass four dowels (18) of variable length, which is predefined by the user. The adapter has two other blind holes where the spikes (19) are mounted. Also shown in FIG. 6 is the connection between the adapter (16) and the connecting piece by cylindrical pins (20).

[0042] FIG. 7 schematically illustrates the connection of the adapter subset to the force applicator subset through the coupling pin (21) in the chute (10) of the force applicator subset, both by fitting. In order to sustain the relative movement between the force applicator subset and the adapter subset a spherical end spring screw (23) is placed.

[0043] FIG. 7 also shows the connection between the adapter (16) and the connecting piece (15) by cylindrical pins (20).

EXAMPLE

[0044] During the graft tensioning stage and in the fixation phase, the adapter subset is fitted to the patient's leg near the tibial tunnel opening before the graft is inserted into the knee. The alignment cone (17) is inserted into the tunnel until it is fitted. Due to its variable diameter geometry this adjustment is almost automatic.

[0045] Then the user has two possibilities for fixing the adapter subset: the fixing by dowels (18) and the fixing with two spikes (19). The first fixing method is carried out using dowels (18) of varying length, which pass inside the through holes in the adapter (16) embedded in the bone. The through holes allow various combinations of use of the dowels (18) so that the device easily adapts to different anatomical regions. The second fixation method is accomplished by two spikes (19) and an elastic strap (optional), fitted into the blind holes of the adapter (16), which upon contact with the bone prevent the movement of the adapter subset. In these cases, the user does not want a fixation with great stability, for anatomical or clinical reasons. The fixation with the dowels (18) is used when a more stable fixation is required, in opposition to the fixation with the use of only the spikes (19) in which there is only an accommodation or contact of the device to the patient.

[0046] After the stability of the fixation is ensured, the alignment cone (17) is removed with a slight rotation and the suture wires of the graft are placed in the empty space left by the alignment cone (17). Then the force applicator subset is attached to the adapter subset using the coupling pins (21). The user may control the required force through the spherical end spring screw (23) to ensure that the subassemblies do not separate at the stage of tensioning.

[0047] The device is installed after insertion of the sutures wires into the suture wire securing parts (8).

[0048] To apply the tensile force to the graft, the user must place one hand on the handle (14) and the other hand on the lateral chute (10) of the device, so that the user is comfortable to perform the traction movement. If the user moves the handle (14) away from the knee, the graft begins to be tensioned. The modulus of the applied force can be observed on the scale, as the inner guiding axle (1) of the helical compression spring (4) is exposed.

[0049] Upon reaching the required tensile force, the user can release the handle (14), and the brake lever (12) is forced to return to the resting position by the micro-spring (11). After performing the cyclic tests for graft adjustment in the housing tunnels, the user can change the force applied to the graft, if it is necessary. Once the user is satisfied with the applied force to the graft tensioning, the user can fix the graft to the tibia. At this stage the dowels (18) are removed and the device is taken out from the leg. At the end of the surgery the device is sterilized in autoclave along with the other tools used.