Device for the correction of a flat feet deformity

Abstract

A device (1) for the correction of a flat feet deformity comprising a rod (2) having a cylindrical symmetry around an axis (X) and comprising a proximal end (5), a distal end (6), which is tapered outwards to allow insertion, and a threaded central portion (7), which is interposed between the proximal end (5) and the distal end (6); an annular sealing element (3), which is coaxial to the axis (X) and is fitted, in use, onto the proximal end (5); and a head (4) provided with a through hole (16), which is coaxial to the axis (X) and is suited to accommodate the assembly formed by the annular sealing element (3) fitted on the proximal end (5); and provided with an outer surface (22) having a curved profile with a dimension measured along the axis (X) variable from a minimum height (HMIN) to a maximum height (HMAX); wherein the head (4) can rotate around the axis (X) independently of the rod (2).

Description

[0001] DEVICE FOR THE CORRECTION OF A FLAT FEET DEFORMITY

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This Patent Appl ication claims priority from Italian Patent Application No . 102023000000942 filed on January 23 , 2023 , the entire disclosure of which is incorporated herein by reference .

[0004] TECHNICAL FIELD

[0005] The present invention relates to a device for the correction of a flat feet deformity . PRIOR ART

[0006] As is well known, the flat foot is a shape of the foot characteri zed by the flattening of the plantar vault , that is , that portion of a plantar surface which, under normal and physiological conditions , does not come into contact with a support surface when the patient is standing .

[0007] In particular, patients suf fering from a flat feet deformity have mispositioning of the calcaneus ( the heel bone ) relative to the astragalus ( the ankle bone ) ; under normal conditions , the astragalus is above the calcaneus , whereas in the case of patients suf fering from a flat feet deformity, the astragalus slides inward and forward, causing pronation of the calcaneus .

[0008] The most common surgical treatment in order to correct the flat feet deformity is known as the calcaneal-stop approach and involves the introduction into the sinus tarsi

[0009] ( i . e . , into the space defined between the calcaneus and the astragalus ) of a device , which is inserted into the calcaneus causing the astragalus to li ft , which consequently nulli fies the flat shape of the plantar vault .

[0010] In particular, said device consists of a screw made of a biocompatible material , preferably titanium alloy .

[0011] The screw comprises a rod having a symmetry around an axis of rotation and provided with a tapered distal end and a threaded portion; and a head provided with an upper hexagonal hole for screwing and an outer surface having an uneven height , along the axis of rotation, which is variable between a minimum height and a maximum height . In other words , the head is arranged in an eccentric position in relation to the rod .

[0012] In greater detail , the surgical treatment known as the calcaneal-stop approach involves making an incision of a few centimetres to obtain a lateral access ( j ust below and anterior to the patient ' s lateral malleolus ) at the patient ' s sinus tarsi .

[0013] Once the incision has been made , the screw is introduced into the sinus tarsi and inserted into the calcaneus until the rod reaches a predetermined height and the head reaches a predetermined angular position . Finally, once the predetermined angular position and height have been reached, the surgeon can proceed in a known way to close the incision by applying a few stitches .

[0014] However, the device of the type described in the foregoing discuss ion has a drawback linked to the fact that it is not possible to decouple the angular adj ustment of the head from the adj ustment of the insertion height of the rod .

[0015] Documents W02013105123 , US 6136032 , US2005251264 and EP2567677 describe examples of known devices for the correction of a flat feet deformity .

[0016] DESCRIPTION OF THE INVENTION

[0017] Therefore , the obj ect of the present invention is to provide a device for the correction of a flat feet deformity, which is free from the drawbacks described above , and particularly, easy, and inexpensive to implement .

[0018] According to the present invention, a device for the correction of a f lat feet deformity is provided, as claimed in the appended claims .

[0019] BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will now be described with reference to the accompanying drawings , which illustrate a non-limiting embodiment thereof , wherein :

[0021] Figure 1 is a perspective , exploded view of a device for the correction of a flat feet deformity provided in accordance with the present invention; Figure 2 is a front view of the device in Figure

[0022] 1;

[0023] Figure 3 is a sectional view along the line III- III of the device in Figure 2;

[0024] Figure 4 is an enlarged view of a detail in Figure 3;

[0025] Figure 5 is a perspective view of the device in Figure 1 inserted in a patient's foot.

[0026] PREFERRED EMBODIMENTS OF THE INVENTION

[0027] In Figure 1, the numeral 1 indicates, as a whole, a device for the correction of a flat feet deformity.

[0028] In particular, the device 1 is made using a screw designed to be fixed into a calcaneus HE (heel bone) of a patient suffering from a flat feet deformity, as better described in the description below.

[0029] The screw 1 is made of a biocompatible material, preferably a metallic material. According to a preferred variant, the screw 1 is entirely made of titanium alloy.

[0030] The screw 1 comprises a rod 2, an annular sealing element 3, and a head 4.

[0031] The rod 2 has a symmetry around an axis X and comprises a proximal end 5 intended to be coupled to the annular sealing element 3 and the head 4, and a distal end 6, which is tapered towards the outside of the screw 1. The rod 2 further comprises a threaded central portion 7 intersected between the proximal end 5 and the distal end 6. The proximal end 5 is provided with an outer surface 8 having a curved profile .

[0032] The rod 2 is internally hollow, i.e., it is provided with a through hole 9, which is coaxial to the axis X and has an uneven diameter. In particular, the through hole 9 is divided into an upper portion 10, which is substantially obtained in the area of the proximal end 5, having a maximum diameter Di and defining a hexagonal hole; and a lower portion 11, which is substantially obtained in the area of the distal end 6 and of the threaded central portion 7, presenting a cylindrical shape and having a diameter D2 which is smaller than the diameter Di .

[0033] The annular sealing element 3 is coaxial to the axis X and is provided with an opening (shown in Figure 1) , i.e., the circumference of the annular element 3 is not complete; said opening allows the annular element 3 to be easily fitted onto the proximal end 5.

[0034] The annular sealing element 3 is provided with an inner surface 12 having a curved profile, which is complementary to the profile of the outer surface 8. The annular sealing element 3 is also provided with a flat upper surface 13, which, in use, defines a support for the head 4, and an outer surface 14 from which a coupling appendage 15 (a tooth) radially projects outwards (i.e., towards the head 4) in order to create a coupling to the head 4.

[0035] The head 4 can rotate around the axis X and is internally hollow, i.e., it is provided with a through hole 16, which is coaxial to the axis X and presenting an uneven diameter. In particular, the through hole 16 is defined by an upper surface 17, which has a maximum diameter D3 and constitutes a hexagonal hole, a central surface 18, which has a curved profile, and a lower surface 19, which is substantially cylindrical and presenting a diameter D4, which is greater than the diameter D3.

[0036] The lower surface 19 is provided with a seat 20, which, when in use, is suited to accommodate the coupling appendage 15. In addition, the central surface 18 and the lower surface 19 are connected to each other by a shoulder 21 which, when in use, abuts against the flat upper surface 13.

[0037] As shown in Figure 2, the head 4 is provided with an outer surface 22 having a curved profile. Moreover, the outer surface 22 presents an uneven height. In particular, the height of the outer surface 22 measured along the axis X is variable from a minimum height HMIN to a maximum height HMAX, as measured from a base surface 23. In other words, the head

[0038] 4 is eccentric in relation to the rod 2. The minimum height HMIN ranges from 50% to 90% of the maximum height HMAX ,' preferably, the minimum height HMIN ranges from 65% to 80% of the maximum height H AX .

[0039] Importantly, the screw 1 described in the foregoing discussion allows the head 4 to rotate around the axis X independently of the rotation of the rod 2 . In other words , the head 4 can rotate around the axis X independently of the rod 2 . Advantageously, the head 4 can rotate around the axis X independently o f the rod 2 until the rod 2 is finally fixed in the bone tissue . Once the rod 2 is finally fixed in the bone tissue , the head 4 is no longer free to rotate around the axis X due to pressure contact between the head 4 and the bone surface . In other words , once the rod 2 is finally fixed in the bone tissue ( i . e . , the rod 2 is tightened in the bone tissue ) , the rod 2 presses on the head 4 , which locks by friction with the bone surface .

[0040] According to a further embodiment , the rod 2 is provided with a hole 9 coaxial to the axis X, which is obtained in the area of the proximal end 5 , having a maximum diameter Di and defining a hexagonal hole ; in other words , the hole 9 is not a through hole and the rod 2 is not internally hollow .

[0041] The following describes the surgical treatment for the correction of a flat feet deformity by means of the device 1 described in the foregoing discussion . At a preliminary stage in the production of the device

[0042] 1 , the annular sealing element 3 is fitted onto the rod 2 and, subsequently, the assembly formed by the annular sealing element 3 and the rod 2 is coupled to the head 4 by inserting the appendage 15 into the seat 20 .

[0043] Subsequently, the surgical treatment involves introducing the device 1 percutaneously through an incision of a few centimetres made to obtain a lateral access ( j ust below and anterior to the patient ' s lateral malleolus ) ; in greater detail , the incision is made at the sinus tarsi ST , i . e . , the space defined between the calcaneus HE and the astragalus AS ( the ankle bone ) of the patient .

[0044] Once the incision has been made , the device 1 is introduced into the sinus tarsi ST and inserted into the calcaneus HE . In particular, the surgeon screws the rod 2 into the calcaneus HE up to a predetermined height .

[0045] The head 4 gets to be housed in the sinus tarsi ST below the astragalus AS , which is thus li fted, thereby raising the plantar vault and opposing the pronation of the calcaneus HE in order to correct the flat feet deformity .

[0046] The surgeon then rotates the head 4 around the axis X until it reaches a predetermined angular position . It appears that i f the portion of the head 4 with the minimum height HMIN is arranged below the astragalus AS , this will result in a lower li fting than i f the portion of the head 4 with the maximum height HMAX were arranged below the astragalus AS . In other words , the head 4 is rotated around the axis X according to the correction that is desired, i . e . , according to the li fting of the astragalus AS that is desired . Finally, once the predetermined angular position has been reached by rotating the head 4 around the axis X, the surgeon can proceed in a known way to close the incision by applying a few stitches .

[0047] It appears clear that the device 1 described in the previous discussion allows the angular adj ustment of the head 4 to be decoupled from the adj ustment of the insertion height of the rod 2 ; furthermore , the device 1 described in the previous discussion adapts very well to the bone surface of the astragalus AS and the calcaneus HE . LIST OF REFERENCE NUMBERS

[0048] 1 device for flat feet correction

[0049] 2 rod

[0050] 3 annular sealing element

[0051] 4 head

[0052] 5 proximal end

[0053] 6 distal end

[0054] 7 central portion

[0055] 8 outer surface

[0056] 9 through hole

[0057] 10 upper portion 11 lower portion

[0058] 12 inner surface

[0059] 13 upper surface

[0060] 14 outer surface

[0061] 15 appendage

[0062] 16 through hole

[0063] 17 upper surface

[0064] 18 central surface

[0065] 19 lower surface

[0066] 20 seat

[0067] 21 shoulder

[0068] 22 outer surface

[0069] 23 base surface

[0070] X axis

[0071] DI diameter

[0072] D2 diameter

[0073] D3 diameter

[0074] D4 diameter

[0075] HE calcaneus

[0076] AS astragalus

[0077] ST sinus tarsi

Claims

CLAIMS1.- A device (1) for the correction of a flat feet deformity comprising:- a rod (2) having a cylindrical symmetry around an axis (X) and comprising a proximal end (5) , a distal end (6) , which is tapered outwards, and a threaded central portion (7) , which is interposed between the proximal end (5) and the distal end (6) ;- an annular sealing element (3) , which is coaxial to the axis (X) and is fitted, in use, onto the proximal end ( 5 ) ; and- a head (4) provided with a through hole (16) , which is coaxial to the axis (X) and is suited to accommodate the assembly formed by the annular sealing element (3) fitted on the proximal end (5) ; and provided with an outer surface (22) having a curved profile with a dimension measured along the axis (X) variable from a minimum height (HMIN) to a maximum height (HMAX) ; wherein the head (4) can rotate around the axis (X) independently of the rod (2) .2.- The device according to claim 1, wherein the rod (2) is provided with a first hole (9) , which is coaxial to the axis (X) and comprising an upper portion (10) , which is substantially obtained in the area of the proximal end (5) , having a first maximum diameter (Di) and which defines a hexagonal hole.3.- The device according to claim 2, wherein the first hole (9) is a through hole and comprises a lower portion(11) , which is substantially obtained in the area of the distal end (6) and of the threaded central portion (7) , presenting a cylindrical shape and having a second diameter (D2) , which is smaller than the first diameter (Di) .4.- The device according to any one of the preceding claims, wherein the proximal end (5) is provided with an outer surface (8) having a curved profile; and wherein the annular sealing element (3) is provided with an inner surface(12) having a curved profile, which is complementary to the profile of the outer surface (8) .5.- The device according to any one of the preceding claims, wherein the annular sealing element (3) is provided with a flat upper surface (13) , which, in use, defines a support for the head (4) .6.- The device according to any one of the preceding claims, wherein the minimum height (HMIN) ranges from 50% to 90% of the maximum height (HMAX) ; preferably, the minimum height (HMIN) ranges from 65% to 85% of the maximum height (H AX) •7 The device according to any one of the preceding claims, wherein the head (4) is provided with a second through hole (16) , which is coaxial to the axis (X) and presenting an uneven diameter.8.- The device according to claim 7, wherein the second through hole (16) is defined by an upper surface (17) , which has a third maximum diameter (D3) and constitutes a hexagonal hole, and a lower surface (19) , which is substantially cylindrical and presenting a fourth diameter (D4) , which is greater than the third diameter (D3) .9.- The device according to any one of the preceding claims, wherein the annular sealing element (3) is provided with an outer surface (14) , from which an appendage (15) radially projects outwards in order to create a coupling to the head ( 4 ) .10.- The device according to claim 9, wherein the head (4) is provided with a second hole (16) having a lower surface (19) provided with a seat (20) suited to accommodate, in use, the coupling appendage (15) .

Images