Articulated device for the wrist

Articulated device (1) for the wrist comprising: a proximal connector (2) for housing a proximal attachment system for pins; —a distal connector (3) for housing a distal attachment system for pins; an articulator joint (4) to provide a controlled movement between the proximal connector (2) and the distal connector (3), characterized in that said articulator joint (3) comprises an arched element (5) that is rotatably mounted on a support element (6) in order to enable rotation around an axis of rotation (X) corresponding to the axis of rotation by flexion and extension of the wrist, said arched element (5) being directly connected to the distal connector (3), blocking means (51) to block the rotation of the arched element (5) and rotation-limiting means (53) to limit the rotation of the arched element (5) for a pre-established portion of a circumferential arc are both directly mounted on said support element (6), and in that said support element (6) is mounted by means of a simple cardan joint (40) on the proximal connector (2), said simple cardan joint (40) presenting a first axis of rotation (Z) that is perpendicular to the axis of rotation (X) of the arched element and a second axis of rotation (Y) that is perpendicular to the first axis of rotation (Z) and movable with respect to the axis of rotation (X) of the arched element along a circumferential arc whose center is located on the first axis of rotation (Z).

FIELD OF APPLICATION

The present invention applies to the field of articulated devices used for the treatment of fractures in the wrist region.

PRIOR ART

For wrist fractures the treatment can be bloodless (reduction and constriction in a brachio-metacarpal or antibrachio-metacarpal plaster device for 5-6 weeks) or surgical, which is nowadays resorted to more often than in the past, of osteosynthesis with external fixation systems in radius distal metaepiphyseal fractures or with plate and pins.

Referring to external fixators, they can be divided, according to the type of functions the fixator is able to perform during or after its application to a patient, into: real stabilizers or articulated devices.

Stabilizers are characterized in that they allow a group of proximal pins to be connected to a group of distal pins, these pins can be directly applied onto a rod or into a clamp. These stabilization devices require a correct fracture reduction before tightening clamps.

Articulated devices can be of the type allowing compression and distraction in the fracture site to be performed after being suitably attached to the limbs by means of groups of proximal and distal pins or of the type allowing, besides enabling a compression/distraction to be performed, also the joint to be moved after attaching the device to the limbs.

In particular, the above-mentioned articulator devices of the last type quite generally comprise a proximal attachment system for the pins, a distal attachment system for the pins and an articulator joint, which is connected to the respective proximal and distal systems by means of suitable connection devices.

Some articulator devices belonging to this last category are known, intended to allow the hand to move with respect to the wrist during the recovery step.

In order to better repeat the natural movements of the wrist joint, some devices have been developed, that are extremely complex from the structural point of view, with large overall dimensions, complicated to apply for the doctor and uncomfortable to use for the patient as well.

The devices that on the contrary have not at least one of these drawbacks are distinguishable by their limited effectiveness in reproducing at best the joint movement.

The technical problem underlying the present invention is therefore to provide an articulated device for the wrist allowing the patient wearing it to move the hand in a natural way with respect to the wrist without compromising the recovery, within a simple, extremely compact and easy-to-use structural solution.

Moreover, the articulated device for the wrist according to the present invention allows the wrist to be kept in a fixed position with respect to bones when that use is required.

In addition, the articulated device for the wrist according to the present invention allows both a compression-extension movement and an abduction-adduction movement or selectively only one thereof to be performed.

SUMMARY OF THE INVENTION

Said technical problem is solved by an articulated device for the wrist according to claim1.

Further features and advantages will become more apparent from the following detailed description of some preferred, but not exclusive, embodiments of the present invention, with reference to the attached figures, given by way of non-limiting examples.

DETAILED DESCRIPTION

Referring to the attached figures, and particularly toFIGS. 1-5, an articulated device for the wrist according to the present invention has been indicated with reference number1.

The articulated device1for the wrist comprising, more generally:a proximal connector2for housing a proximal attachment system for pins that are inserted in a proximal bone of the fracture,a distal connector3for housing a distal attachment system for pins that are inserted in a distal bone of the fracture;an articulator joint4to provide a controlled movement between the proximal connector2and the distal connector3.

In the example shown the proximal connector2and the distal connector3actualize in a proximal rod and in a distal rod respectively that the clamps supporting the pins can be attached to, the latter ones, in case of fracture in the wrist region, such as for example distal radius fractures, are attached to the radius and to metacarpal bones respectively.

According to the present invention, the articulator joint4comprises an arched element5that is rotatably mounted on a support element6in order to enable rotation around an axis of rotation X located in correspondence with the instant center of rotation of the wrist (as it can be seen inFIG. 4). The arched element5is connected, at an end thereof, to the distal rod3by means of a peg31that is inserted into a corresponding seat that is present in the arched element5.

Suitable blocking means for blocking the rotation of the arched element5and rotation-limiting means for limiting the rotation of the arched element5for a pre-established portion of a circumferential arc are both directly mounted on the support element6. These blocking means and limiting means will be better described hereafter.

According to the invention, the support element6is mounted by means of a simple cardan joint40on the proximal connector2, this simple cardan joint40has a first axis of rotation Z that is perpendicular to the axis of rotation X of the arched element5and a second axis of rotation Y that is perpendicular to the first axis of rotation Z, this latter axis Z is movable with respect to the axis of rotation of the arched element X along a circumferential arc whose center is located on the first axis of rotation Z.

The articulated device1can act as an external fixator having the various elements composing it blocked together.

In the example shown, the arched element5has a hole5bpassed through by a pin52which it is hinged on. The pin52has a hole in its center to allow a Kirchner wire to pass through, that hole has a central axis coinciding with the axis of rotation X.

In practice, the center of rotation of the arched element5coincides with the center of rotation of the wrist, in order to obtain a perfect centering of the articulated device1.

In the preferred embodiment of the present invention, the blocking means of the rotation of the arched element5comprise a locking grub screw51that can be operated in rotation from the outside, whose end is intended to abut against an edge of the arched element5. The limiting means comprise on the contrary an axially displaceable insert53. In the example, the insert53is provided with a threaded channel53bwhich the blocking grub screw51screws into.

The blocking grub screw51is provided on the head with a shaped impression, preferably hexagon-like, for engaging with a screwing tool.

The insert53has a cylindrical shape, whose threaded channel53bwhich the blocking grub screw51passes through extends transversely, moreover it has an eccentric body53aat an end thereof that is intended to abut against a ribbed profile5athat is present on a perimeter portion of the arched element5.

The insert53is axially movable along an axis K between a position wherein the eccentric body53ais inserted into the rib5aof the arched element5therefore limiting the angular travel of the arched element to about 45°. When on the contrary the insert53is operated in order to move the eccentric body53aaway till going out of the rib5a, the arched element5is free to rotate along a circumferential arc of about 60°-80°.

The operation along the axis K of the insert53can occur also tangentially moving the grub screw51inserted into the insert53.

A friction ring54is located within an annular rib53cthat is present in correspondence with the eccentric body53a.

The simple cardan joint40comprises a connecting element41formed by a pair of annular elements41a,41bhaving the respective central axis corresponding to the first and second axis of rotation Z, Y. These annular elements41a,41bare joined together by a central connection element41cin order to form a single piece.

In order to control the movements of the simple cardan joint40, a first blocking screw42to block the rotation around the first axis of rotation Z and a second blocking screw43to block the rotation around the second axis of rotation Y are provided.

Both the first and the second blocking screws42,43are provided on the head with a shaped impression, preferably hexagon-like, for engaging with a screwing tool.

The proximal rod2is connected to the simple cardan joint40by means of a distraction/compression device20.

This distraction/compression device20comprises a distraction/compression body21having a threaded hole which a distraction/compression pin22operated by a ring nut23screws into.

A blocking screw24of the distraction/compression pin22screws into a transversal threaded hole22aof the distraction/compression pin22passing through a slot21bthat is present on the distraction/compression body21.

The proximal rod2is attached to an end of the distraction/compression pin22.

The connection between the arched element5supporting the distal rod3and the distraction/compression device20supporting the proximal rod2is thus performed by means of the simple cardan joint40.

In particular, an annular element41aof the simple cardan joint40is connected to the support element6by means of the first blocking screw42acting as a pin of rotation around the axis Z. In the example, the annular element41ais interposed between a pair of rings6athat are present on the support element6.

While the other annular element41bof the simple cardan joint40is connected to the distraction/compression body21by means of the second blocking screw43acting as a pin of rotation around the axis Y. In the example, the annular element41bis interposed between a pair of rings21athat are present on the distraction/compression body21.

In the example, the support element6has a fork-like shape having two opposing arms which the arched element5rotates in.

When the two proximal and distal rods are substantially aligned along a common line, the arc subtended between this common line and the line developing along the longitudinal extension of the fork arms is equal to about 45°. Due to this particular arrangement, the overall dimensions of the articulated device1are extremely reduced.

In the example shown, the pin52passes through two opposing holes that are present at one end of the arms of the support element6, while the insert53passes through two opposing holes that are present at the other end of the arms of the support element6. These last two holes have the central axis that is perpendicular to the central axis of the pair of rings6awhich the first blocking screw42passes through and parallel to the axis X of the pin52.

Preferably, the arched element5is made of a radio-transparent material, such as for example peek reinforced with carbon fibers; the pin52is made of steel and the support element6of aluminum alloy, but with a thickness not preventing x-ray transparency in order to see the fracture site.

The support element6, in correspondence with the end which the pin52passes through has a circular element6bwhose center is in line with the axis of rotation X.

In practice, the pin52, that is channeled to allow the Kirchner wire to pass through, and the circular element6bhave the same central axis, corresponding to the axis of rotation X of the arched element5.

In this way, when centering the device1by means of an X-ray inspection in scopy (continuous exposition to soft x rays), the operator is helped in centering due to the fact that he observes the circular element6b(sub-transparent) and the pin52(completely opaque) centered on the same axis.

The circular element6bhas a higher radius than that of the pin52, therefore, when they are in line, a small circle represented by the pin52within the greater circle represented by the circular element6bcan be observed in scopy.

As it can be appreciated from the above, the device according to the present invention allows the requirements and drawbacks mentioned in the introduction of the present description with reference to the prior art to be met and overcome.

Of course, a person skilled in the art can apply numerous modifications and variants to the above-described above, in order to satisfy contingent and specific requirements, all of which are covered by the scope of protection of the invention, as defined by the following claims.