Device for external orthopedic fixations

A device for external orthopedic fixations, which has one or more frames which have a substantially and/or partially annular shape and are suitable for being arranged around a limb to surround it at least partially, wherein one or more rods are fixed to a frame by means of a locking mechanism is provided. The device has two jaws which, when closed, tighten the locking mechanism to a portion of the frame by exerting a prevalently axial force, wherein the jaws are closed by means of a cam mechanism suitable for being actuated by rotating a lever pivoted to a first jaw and provided with one or more cam surfaces cooperating with a surface of the second jaw.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 of PCT/IB2015/055819, filed Jul. 31, 2015, which claims the benefit of Italian Patent Application No. MI2014A001499, filed Aug. 14, 2014.

FIELD OF THE INVENTION

The present invention relates to a device for external orthopedic fixations, in particular a device of the type also known as Ilizarov apparatus.

BACKGROUND OF THE INVENTION

US 2012/203225 A1 and U.S. Pat. No. 5,888,197 describe devices for orthopedic fixations comprising two or more frames which can be arranged next to a limb and are connected by a rod fixed to the frames by means of a locking mechanism comprising two jaws which can be closed by a cam mechanism provided with a lever to tighten a locking mechanism to a portion of the frame. The frames of these known devices, being formed by straight bars, cannot be arranged around a limb, in particular to arrange wires, bars or nails in a radial configuration with respect to this limb, as it is instead necessary in the Ilizarov apparatuses. The jaws also exert a force perpendicular to the axis of the frame to which are tightened, then a force which is not prevalently axial.

US 2013/0018374 A1 describes a device for orthopedic fixations comprising two frames of annular shape that can be arranged around a limb and are connected by a plurality of rods fixed to the frames by means of locking mechanisms comprising two jaws which can be closed by a cam mechanism provided with a lever. These jaws do not tighten the frames but bring near two pins which are inserted in corresponding longitudinal holes formed in the frames to prevent the sliding of a locking mechanism around a frame, otherwise possible through a screw kinematic mechanism.

This known device has a relatively complex structure which makes the device expensive and complex to use. In addition, the operation of this known device requires the presence of many metal parts that make the same device heavy and opaque to X-rays, so as to adversely interfere during radiological examinations. Moreover, the rods may be fixed only in a limited number of positions corresponding to the number of holes formed in the frames, so as to prevent a precise application of wires, bars or nails in a radial configuration with respect to the limb, as is instead required in the Ilizarov apparatuses.

DE 40 13 822 A1 describes a device for orthopedic fixations comprising two frames of annular shape that can be arranged around a limb and are interconnected by a plurality of rods fixed to the frames by means of a screw locking mechanisms that apply an axial force on a frame but also make difficult its use in a medical field because of the opacity to X-rays of the screws and of the relative complexity and slowness of their tightening in critical situations.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide a device free from said drawbacks. Said object is achieved with a device whose main features are specified in the first claim, while other features are specified in the remaining claims.

Thanks to the particular structure of the rods, of the frames and of the locking mechanisms, the device according to the present invention is relatively light and easy to use, and can be integrally or nearly integrally made of a material transparent to X-rays, in particular of a composite material.

Also, the locking mechanisms tighten the rods to the frame with a quick and precise cam mechanism, so as to speed up and simplify the procedures for installation or removal of the device around the limb, which procedures are generally critical both for the patient and the doctors assisting him.

The locking mechanisms are also provided with special seats which prevent or limit the movements of the rods with respect to these mechanisms when the jaws are tightened to the frame, so as to provide a dual locking or unlocking function by operating a single lever.

The frames preferably comprise more portions which can be joined together in a simple and fast manner and which can be provided with radial holes which allow the direct assembly of mechanical devices and/or wires in tension and/or be equipped with arched grooves and ribs to limit the relative positions of the locking mechanisms with respect to the frames. Thanks to the particular shape of the ends of the frames portions, the locking mechanisms may be fixed at any point of the frame, also at these ends.

The rods which are connected to the frame by means of the locking mechanisms may be provided with special clamps or housings that allow to orient and maintain in specific positions with respect to the rods themselves the elongated members which connect the limb to the present device. In particular, the housing of a rod can contain a cable clamp and be provided with a slot, so as to simplify and speed up the procedure in which a wire suitable to connect the limb to the present device is fixed to the rod.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIG. 1, it is seen that the present device comprises in a known way one or more frames, in particular two frames1of a substantially and/or partially annular shape, which are adapted to be placed around a limb, for example of a person or an animal, for at least partially surrounding this limb. One or more first rods, in particular four first rods2(a first rod is hidden inFIG. 1), connect the two frames1and can be fixed in a removable manner to at least a frame1by means of at least one first locking mechanism3. One or more elongated members, for example wires4, bars or nails5, can be fixed in removable manner to at least one frame1, directly, such as wires4in the figure, or by at least one second locking mechanism6, such as for example nails5. These elongated members4,5are adapted to penetrate into at least one bone7in the limb provided with the present device, for example for fixing two portions of bone7which are separated by a fracture8. Rods2may be lengthened or shortened, for example by rotating axially at least one threaded bush9in which threaded ends of two portions of a rod2are screwed.

Referring now also toFIGS. 2 and 3, it is seen that the first locking mechanism3comprises at least two jaws10,11which, when closed, tighten the locking mechanism3to a portion of the frame1. When they are closed and tighten the portion of frame1, jaws10,11exert a force prevalently axial, namely along a longitudinal axis L of frame1, in particular an axis substantially parallel to the central axis C of frame1. To tighten the portion of frame1, jaws10,11can be closed by means of a cam mechanism operated by rotating at least one lever12. In particular, lever12can be pivoted to a first jaw10and be provided with one or more cam surfaces, in particular two cam surfaces13(one of these surfaces is shown with a dashed line inFIG. 2) cooperating with at least one surface of the second jaw11. Lever12can be pivoted to the first jaw10by means of one or more pins, in particular two pins14,14′ aligned to each other and inserted in holes formed in two walls10a, having for example a substantially triangular profile, which extend from the first jaw10, and in two walls12a,12a′, having for example a substantially elliptical profile, which extend from lever12and comprise a cam surface13. The free end of lever12may be provided with an opening15for tying lever12to a rod2with a clamp16, so as to prevent the accidental rotation of lever12and therefore the opening of jaws10,11. The locking mechanism3may comprise one or more seats17,18for a rod2. Seats17,18are preferably arranged between the two walls10awhich extend from the first jaw10. Seats17,18have a shape substantially complementary to the shape of a portion2aof rod2. In the present embodiment, the portion2aof rod2is substantially spherical and/or is arranged at one end of rod2and/or seats17,18have a concave shape adapted to receive a sphere portion having substantially same diameter of portion2aof rod2. When jaws10,11are closed and tightened on frame1, seats17,18tighten portion2aof rod2, thus preventing a relative movement of rod2with respect to at least one axis of the locking mechanism3and then of frame1. Seat17of the first jaw10is connected with the outside through at least one opening19having a substantially frustoconical shape, in particular having an apex angle less than 80° and/or greater than 30°.

The cross-section of a portion of frame1may be substantially elliptical, with the major axis of the ellipse substantially parallel to the longitudinal axis L. Frame1can also be provided with one or more radial holes, in particular a series of radial holes20spaced with a pitch comprised between 3° and 10°. One or more mechanical devices can be inserted in the radial holes20. In particular, one or more wires4can be stretched between two holes20and locked by two cable clamps21, in particular having a substantially cylindrical shape with the central axis substantially parallel to the longitudinal axis L of frame1. The inner end of the radial holes20is preferably countersunk, so that a wire4can be stretched without abrupt angles between two holes which are not aligned along a diameter of frame1. The internal profile of jaws10,11has a concave profile substantially complementary to the external profile of a portion of frame1, for example a profile substantially as an arc of ellipse. Frame1also has one or more protuberances or recesses, such as a circular or partially circular rib22arranged along the inner edge of frame1and/or between the free ends of jaws10,11, so as to guide and arrange the latter in a defined position when they are closed and tightened on frame1.

Referring toFIG. 4, it is seen that the first locking mechanism23according to a second embodiment is substantially equal to the first locking mechanism3, with the difference that seats24and25are slightly bigger than portion2aof rod2, in particular they together form a substantially spherical seat having a diameter greater than the diameter of portion2aof rod2, so that portion2aof rod2can rotate around one or more axes, in particular around three axes, in seats24and25.

In general, in the blocking mechanisms according to the present invention the seats for the rods may be shaped so that when the jaws are closed and tightened on the frame a rod can rotate around one, two or three axes, for example around the central axis of the rod and/or around a radial axis of the frame and/or around an axis tangential to the frame, and/or translate along an axis with respect to the locking mechanism.

Referring toFIGS. 5 and 6, it is seen that the second locking mechanism6is similar to the first locking mechanism3since it also comprises at least two jaws30,31adapted to be closed to tighten the locking mechanism6to a portion of frame1by exerting a force prevalently axial, namely substantially parallel to the longitudinal axis L of frame1. To tighten the portion of frame1, jaws30,31are adapted to be moved towards each other by at least one lever32which can be pivoted to a first jaw30and be provided with one or more cam surfaces, in particular two cam surfaces33cooperating with at least one surface of the second jaw31. Lever32can be pivoted to the first jaw30by means of one or more pins, in particular two pins34aligned with each other and inserted in holes formed in two walls30a, having for example a substantially triangular profile, which extend from the first jaw30, and two walls32a, having for example a substantially elliptical profile, which extend from lever32and which comprise a cam surface33. The free end of lever32may be provided with an opening35for tying lever32to a rod36with a clamp, so as to prevent the accidental rotation of lever32and therefore the opening of jaws30,31. The locking mechanism6may include one or more seats37,38for rod36. Seats37,38have a shape substantially complementary to the shape of a portion36aof rod36. In the present embodiment, portion36aof rod36is substantially cylindrical and seats37,38have a concave shape, in particular substantially cylindrical, adapted to receive a portion of a cylinder having substantially the same diameter of portion36aof rod36. In particular, seat38of jaw31has externally a substantially frustoconical shape, which is provided with longitudinal slots (not visible in the figures) and which is complementary to a cavity, also for example with a substantially frustoconical shape, of seat37of jaw30for rod36. When jaws30,31are tightened on frame1, seats37,38are coupled, seat38of jaw31is deformed internally through the longitudinal slots and it tighten portion36aof rod36, thus preventing a sliding along its axis and/or a rotation around this axis of rod36relative to the second locking mechanism6and thus relative to frame1. Rod36may in turn be provided with a clamp39, in particular made in one piece with rod36, to mechanically connect, in particular by tightening it with a screw40, a nail5to frame1through the second locking mechanism6. Clamp39is preferably arranged at one end of rod36and preferably comprises a mobile part so that nail5can form with the central axis of rod36at an angle comprised between 60° and 120°.

Referring toFIGS. 7 to 9, it is seen that frame1may have a substantially annular shape and/or comprise more frame portions connected to each other, in particular two frame portions1a,1bhaving a half-ring shape. Portions1a,1bof frame1can be joined together by means of a screw41inserted respectively in two holes that are formed at one end of portions1a,1b, are aligned with each other and are substantially parallel to the central axis C of frame1. The adjacent ends of portions1a,1bare shaped with complementary profiles so as to achieve a form coupling in the region in which screw41passes through these holes. With this arrangement, these ends can be locked to each other, so that portions1a,1bform frame1by screwing screw41into a nut42. The ends of portions1a,1bare arranged between the head of screw41, housed in a seat formed in portion1b, and nut42, housed in a seat formed in portion1a, so that neither screw41nor nut42protrude from frame1. With this arrangement a locking mechanism can be fixed to frame1also at screw41. Furthermore, in particular around the hole for screw41, the end of portion1aof frame1is provided with at least one protrusion or recess43which realizes a form coupling with a corresponding recess or protrusion formed at the contiguous end of portion1bof frame1.

Referring toFIG. 10, it is seen that the locking mechanism6can be connected to a rod46according to an embodiment provided with a housing48for a cable clamp49adapted to stretch a wire50between limb7and rod46. The cable clamp49may have a substantially cylindrical shape, so that it can rotate in housing48around an axis A substantially perpendicular to the stretched wire50. Housing48is also preferably provided with a slot51so that wire50can form with rod45an angle comprised between 60° and 120° when the cable clamp49rotates in housing48. In addition, thanks to slot51, wire50already provided with the cable clamp49can be fixed to rod46. Housing48is preferably made in one piece with rod46.

Referring toFIG. 11, it is seen that the second locking mechanism56according to a second embodiment is substantially equal to the first embodiment, as well as similar to the first locking mechanism3, however it comprises two jaws57,58having inner surfaces provided with ribs or grooves59which carry out a form coupling with corresponding grooves or ribs60arranged along arcs of circumference of a frame61according to a second embodiment. Jaws57,58are sufficiently wide to allow the tightening of the locking mechanism56on frame61at a plurality of positions defined by the possible form couplings between ribs or grooves59,60. In this way, a rod46can be fixed to frame61by means of the second locking mechanism56with an orientation parallel to the central axis of frame61or inclined with respect to the latter with a given angle which is comprised between 0° and 30°, for example in steps of 5°, and which it is defined by the relative position of the ribs or grooves59,60.

Referring toFIGS. 12 and 13, it is seen that frame71according to a third embodiment, similar to the first embodiment, is formed by two or more portions71aand71bhaving one end provided with a flexible hook72adapted to be snap-fitted into a corresponding cavity73formed at one end of the adjacent portion71bor71aof frame71. The ends of portions71aand71bof frame71may also be provided with a pin74adapted to be inserted into a corresponding hole75formed at one end of the adjacent portion71bor71a. Pin74is arranged along an axis substantially parallel to an axis tangent to frame71. The flexible hook72and/or cavity73are arranged along the inner wall of frame71. The cross-section of frame71has a substantially trapezoidal shape, with the major base facing the center of frame71and the minor base toward the outside. The major base is slightly convex towards the center of frame71and/or the minor base, namely the outer wall of frame71, can be provided with grooves or ribs76, in particular grooves with the shape of a cylindrical portion substantially parallel to the central axis C of frame71. Grooves76can act as seats for mechanical devices, in particular cable clamps (not shown in the figure) with a substantially cylindrical shape that stretch wires inserted in the radial holes of frame71. For this reason, the radial holes of frame71are arranged substantially at the center of grooves76. The pitch between the grooves or ribs76may be comprised between 1° and 3°.

Referring toFIGS. 14 to 17, it is seen that the second locking mechanism86according to a third embodiment is substantially equal to the first two embodiments, as well as similar to the first locking mechanism3, however it comprises at least two jaws87,88which have a curved profile, for example hook-shaped, complementary with the outer profile of frame71according to the third embodiment. A portion of the second locking mechanism86, in particular arranged between the two jaws87,88, is provided with ribs or grooves89which carry out a form coupling with the grooves or ribs76arranged along frame71. In this way, the second locking mechanism86can be arranged at given positions along frame71. To tighten the portion of frame71, jaws87,88are closed, so as to be moved one towards the other, by at least one lever90through a cam mechanism as in the blocking mechanisms according to the other embodiments. The second locking mechanism86is also provided with at least one flexible hook91adapted to engage in a seat92formed in lever90, so as to prevent an accidental opening of jaws87,88. The flexible hook91can be bent, for example, with the tip of a screwdriver, to unlock lever90. The second locking mechanism86connects a nail94to frame71by means of a clamp95that can be made in one piece with a rod96and/or is provided with a moving part97that can tighten nail94on clamp95by screwing a screw98.

Referring toFIGS. 18 and 19, it is seen that the second locking mechanism86can also connect wire50to frame71by means of clamp105joined to rod106. Clamp105is provided with a movable part107which can tighten nail94against clamp105. The movable part107comprises in particular a pin inserted in a hole made in clamp105along an axis substantially perpendicular to rod106and/or to nail94. An end of pin107is provided with a head comprising a hole in which nail94can slide, while the other end is threaded, so that a nut108can be screwed around pin107, thus tightening clamp105between nut108and nail94, so that nail94, urged against one side of clamp105, cannot slide in the hole of pin107and prevents the rotation of pin107in clamp105. A helical spring109is arranged around pin107in the hole of clamp105to remove nail94from clamp105when nut108is loosened. Nail94may be fixed to rod106by forming with the central axis of the latter an angle comprised between 60° and 120° according to the rotation of pin107in clamp105.

Referring toFIGS. 20 to 22, it is seen that in a further embodiment rod110may be provided with a clamp111for wire50. Clamp111is provided with a movable part112which can tighten a cable clamp113in which wire50can slide or be blocked by a screw114that can urge perpendicularly to wire50. The movable part112comprises in particular a pin inserted in a hole made in clamp111along an axis substantially perpendicular to rod110and/or to wire50. One end of pin112is provided with a head comprising a housing in which the cable clamp113can slide, while the other end is threaded, so that a nut115may be screwed around pin112, thereby tightening clamp111between nut115and the cable clamp113, so that the latter, being urged against one side of clamp111, cannot slide in the housing of pin112and prevents the rotation of pin112in clamp111. A helical spring116is arranged around pin112in the hole of clamp111to remove the cable clamp113from clamp111when nut115is loosened. Wire50can be fixed to rod110by forming with the central axis of the latter an angle comprised between 60° and 120° according to the rotation of pin112in clamp111.

Frames1,61and/or71, rods2,36,46,96,106and/or111and/or the locking mechanisms3,6,23,56and/or86are preferably made of a composite material, in particular containing carbon fibers, more in particular short carbon fibers (length of between 5 and 200 mm, in particular between 20 and 30 mm), preferably through the manufacturing method described in patent application WO 2013/128312, which is included in its entirety by reference into the present application.

Other embodiments of the first and/or second locking mechanism may include technical features of the first and/or second locking mechanism according to all embodiments described and illustrated here.

Further variants and/or additions may be made by those skilled in the art to the embodiments here described and illustrated remaining within the scope of the following claims. In particular, further embodiments of the invention may comprise the technical features of one of the following claims with the addition of one or more technical features, taken singularly or in any mutual combination, described in the text and/or illustrated in the drawings.