ARTHRODESIS IMPLANT

Abstract

The invention relates to an implant for the osteosynthesis of the PIP arthrodesis or the DIP arthrodesis of small joints and for the osteosynthesis and stabilisation of fractures of small bones of the human skeleton, said implant being resorbable by the human body. The implant consists of two shafts placed against each other. At least one fixing aid is located between the shafts, said fixing aid protruding beyond the diameter of the shaft. Each shaft can optionally have longitudinal grooves and transverse grooves. The implant consists of a magnesium-based material which can be resorbed by the human body. The invention provides an implant which has an extremely high tensile strength, excellent stability, optimal healing properties, and an optimally adapted resorption speed.

Claims

1. An implant for the osteosynthesis of the PIP arthrodesis or the DIP arthrodesis of small joints and for the osteosynthesis and stabilisation of fractures of small bones of the human skeleton, wherein the implant comprises a proximal shaft (1) and a distal shaft (2), which are connected together at an angle of 155 to 175 degrees, wherein each shaft (1, 2) has at least one longitudinal groove (4), and at least one fixing aid (3) between the shafts (1, 2), which protrudes beyond the diameter of the shaft (1, 2), and wherein the length of the shafts (1, 2) is in each case 5.00 to 75.00 mm, the diameter of the shafts (1, 2) is 1.50 to 20.00 mm, the thickness of the fixing aids (3) is 0.10 to 2.00 mm, and the overhang of the fixing aids (3) over the diameter of the shafts (1, 2) is 0.25 to 4.00 mm, and the implant comprises a magnesium-based alloy which is resorbable by the human body and comprises 0.10 to 2.50 wt. % zirconium, 0.01 to 0.80 wt. % zinc, 1.50 to 5.00 wt. % yttrium and 2.50 to 5.00 wt. % other rare earth metals, and the copper and aluminium content in each case is less than 0.20 wt. %.

2. An implant according to claim 1, wherein the number of longitudinal grooves (4) is two to eight.

3. An implant according to claim 1, wherein, on the shafts (1, 2) two to eight fixing aids (3) are provided which are arranged symmetrically around the shafts (1, 2), the thickness of which in the cross-section is 0.10 to 2.00 mm, and which protrude radially beyond the shaft by 0.25 to 4.00 mm.

4. An implant according to claim 3, wherein the thickness in the cross-section of the fixing aids (3) is between 0.20 and 2.00 mm, and the fixing aids (3) protrude radially beyond the shafts (1, 2) by 0.50 to 4.00 mm.

5. An implant according to claim 4, wherein the thickness in the cross-section of the fixing aids (3) is between 0.20 and 1.00 mm, and the fixing aids (3) protrude radially beyond the shafts (1, 2) by 0.50 to 2.00 mm.

6. An implant according to claim 5, wherein the thickness in the cross-section of the fixing aids (3) is between 0.20 and 0.80 mm, and the fixing aids (3) protrude radially beyond the shafts (1, 2) by 0.50 to 1.00 mm.

7. An implant according to claim 1, wherein the length of the shafts (1, 2) in each case is 5.00 to 15.00 mm, the diameter of the shafts (1, 2) is 2.00 to 10.00 mm, the thickness of the fixing aids (3) is 0.20 to 1.00 mm, and the overhang of the fixing aids (3) over the diameter of the shafts (1, 2) is 0.50 to 2.00 mm.

8. An implant according to claim 1, wherein the length of the proximal shaft (1) is 10.00 to 15.00 mm, the length of the distal shaft (2) is 5.00 to 11.00 mm, and the diameter of the two shafts (1, 2) in each case is 2.40 to 3.60 mm.

9. An implant according to claim 1, wherein the angle between the shafts (1, 2) is between 155 to 160 degrees.

10. An implant according to claim 1, wherein the angle between the shafts (1, 2) is approximately 160 degrees.

11. An implant according to claim 1, wherein the one or both shafts (1, 2) have transverse grooves (5).

12. An implant according to claim 1, wherein the magnesium-based alloy comprises 0.10 to 1.00 wt. % zirconium, 4.75 to 5.50 wt. % yttrium and 1.50 to 4.00 wt. % other rare earth metals.

13. An implant according to claim 1, wherein the magnesium-based alloy comprises 0.10 to 1.00 wt. % zirconium, 3.70 to 4.30 wt. % yttrium and 2.40 to 4.40 wt. % other rare earth metals.

14. An implant according to claim 1, wherein the magnesium-based alloy in each case comprises less than 0.10 wt. % copper, iron, nickel and aluminium.

15. An implant according to claim 14, wherein the magnesium-based alloy comprises less than 0.01 wt. % aluminium, less than 0.20 wt. % zinc, less than 0.15 wt. % manganese, less than 0.20 wt. % lithium, less than 0.01 wt. % silicon, less than 0.01 wt. % iron, less than 0.03 wt. % copper and less than 0.005 wt. % nickel.

16. An implant according to claim 1, wherein the number of longitudinal grooves (4) is six.

17. An implant according to claim 1, wherein, on the shafts (1, 2) three fixing aids (3) are provided which are arranged symmetrically around the shafts (1, 2), the thickness of which in the cross-section is 0.10 to 2.00 mm, and which protrude radially beyond the shaft by 0.25 to 4.00 mm.

Description

[0026] The invention is explained by the attached drawings.

[0027] FIG. 1 shows a first embodiment of the invention in a side view.

[0028] FIG. 2 shows the first embodiment of the invention in a cross-sectional view.

[0029] FIG. 3 shows the proximal shaft (1) of the first embodiment in a longitudinal sectional view.

[0030] FIG. 4 shows the distal shaft (2) of the first embodiment of the invention in a longitudinal sectional view.

[0031] FIG. 5 shows a second embodiment of the invention in a side view.

[0032] FIG. 6 shows a third embodiment of the invention in a side view.

[0033] FIG. 1 shows a first embodiment of the invention in a side view. The magnesium alloy used for production contains 0.10 to 2.50 wt. % zirconium, 0.01 to 0.80 wt. % zinc, 1.50 to 5.00 wt. % yttrium and 2.50 to 5 wt. % further rare earth metals. It consists of a proximal shaft (1) and a distal shaft (2). The length of the proximal shaft (1) is 12.40 millimetres and the length of the distal shaft (2) is 6.20 mm. The angle between the proximal shaft (1) and the distal shaft (2) is 160 degrees. Said angle is to be adapted to the physiological conditions of the patient and can, therefore, differ accordingly in other embodiments. Between the proximal shaft (1) and the distal shaft (2), three wing extensions are located as fixing aids (3). These have a thickness of 0.30 mm and a projection of 1.00 mm. The fixing aids (3) quickly dissolve after the operation so that a gap formation between the bones connected by the proximal shaft (1) and the distal shaft (2) is avoided. The shafts (1, 2) are each provided with six longitudinal grooves (4) which bring about an enlargement of the surface of the implant. This in turn influences the resorption rate of the implant. In addition, the longitudinal grooves (4) prevent the implant from rotating in the bone. The combination of the magnesium alloy according to the invention and the special structure results in an implant which has an extremely high tensile strength of up to 300 MPa, has excellent stability, best healing properties and an optimally adapted resorption rate.

[0034] FIG. 2 shows the proximal shaft (1) of the first embodiment in a cross-sectional view. In this case, the three fixing aids (3) are also shown, which are arranged at equal distances around the proximal shaft (1).

[0035] FIG. 3 shows the proximal shaft (1) in a cross-sectional view. The profile of the longitudinal groove (4) can be produced using a radius milling cutter.

[0036] FIG. 4 shows the distal shaft (2) in a cross-sectional view. The distal shaft (2) is also provided with longitudinal grooves (4).

[0037] FIG. 5 shows a second embodiment of the invention. The magnesium alloy used for production contains 0.10 to 2.50 wt. % zirconium, 0.01 to 0.80 wt. % zinc, 1.50 to 5.00 wt. % yttrium and 2.50 to 5.00 wt. % further rare earth metals. There is an angle of 180 degrees between the proximal shaft (1) and the distal shaft (2). Otherwise, this embodiment corresponds to the first embodiment with respect to its dimensions.

[0038] FIG. 6 shows a third embodiment of the invention. The magnesium alloy used for production contains 0.10 to 2.50 wt. % zirconium, 0.01 to 0.80 wt. % zinc, 1.50 to 5.00 wt. % yttrium and 2.50 to 5.00 wt. % further rare earth metals. The proximal shaft (1) and distal shaft (2) have both longitudinal grooves (4) and transverse grooves (5). The transverse grooves (5) lend the implant an improved hold in the bone.

REFERENCE LIST

[0039] 1. Proximal shaft

[0040] 2. Distal shaft

[0041] 3. Fixing aid

[0042] 4. Longitudinal groove

[0043] 5. Transverse groove