Osteosynthetic device for treating subtrochanteric and pertrochanteric fractures and fractures of the neck of the femur

p0001The invention relates to an osteosynthesis aid for supply subtrochanteric, petro chan more advanced and hip fractures according to the preamble of claim 1.

p0002Such a tool is known, for osteosynthesis. For example, from EP 0 486 483 A1. In the known osteosynthesis aids nailing is used to guide and support a femoral neck screw. For this purpose, the locking nail in the proximal area at an oblique bore through which the femoral neck screw can be passed. On fermurkopfseitigen end of the femoral neck screw a self-tapping thread is formed, with which they are anchored in Fermurkopf. To fix the locking nail in the bone two cross bores in the distal region of the locking nail provided. This cross bores a bone screw is passed and tightened respectively.

p0003A disadvantage of this osteosynthesis aids that a static distal fixation of the locking nail is achieved by this structural measure only. A dynamic distal fixation of the locking nail is thus not possible. Also due to the use of bone screws, in particular by tightening the bone screws vulnerabilities for future fracture.

p0004In DE-U 91 02 018, a locking nail is described, which is located at bone fractures, especially in comminuted fractures when bone marrow nail in the bone fragment rotationally secure. This locking nail has to fix the bone in both the proximal region and the distal region of two cross-bores, the proximal transverse bore is formed in the distal portion of an elongate hole-cross hole. In order to achieve a more dynamic fracture, the elongated transverse hole is only occupied the distal circular cross bore in the distal region, however, remains unoccupied. However, such a fixing is possible only in bone fragments, in which the locking nails are exposed to low forces or pressure loads. Under high loads, the locking nail, such as those occurring in the femoral neck bone area, the conventional bone marrow nail can not be used, so that arrive at pertrochanterer, subtrochanteric and femoral neck fractures specially trained osteosynthesis aids are used. Such fractures and stable fixation of the locking nail of the osteosynthesis aid must be guaranteed. A stable fixing is achieved mainly by fixation of the distal region of the locking nail at the femoral neck bone, it is especially very advantageous if the locking nail is designed so that it can be individually adapted to occur there complicated fractures. A stable and individual fixing is not possible with the above bone marrow nail.

p0005Finally, from FR-A 26 68 360. osteosynthesis aids known whose interlocking nail is used to guide and support a femoral neck screw. In order to fix the locking nail in the bone that has both in the proximal and in the distal area each have two circular cross-bores to receive bone screws. In one embodiment, an elongated transverse hole instead of the two circular cross bores in the proximal region provided to be telescoped to locate the proximal region of the locking nail at the femoral neck bone, while he is in the distal region, set or fixed static. However, such dynamic arrangement of the locking nail in the proximal region affected both the necessary firm anchoring of femoral neck screw in Fermurkopf and the fixation of the femoral neck screw with the locking nail, since it is not possible, the axial movement of the lag screw in the oblique passage opening in the proximal portion, for example, a locking pin or the like to limit or completely block.

p0006Object of the present invention is therefore to further develop a osteosynthesis aids of the known type such that a solid and gentle fixation of a locking nail is ensured in the bone, the fixation can be selected in particular as a static or alternatively as dynamic fixation.

p0007This object is achieved by the characterizing features of claim 1.

p0008A core idea of ​​the present invention is to form at least one transverse bore in the distal area of ​​the locking nail as an elongated hole transverse bore through which a distal locking member, in particular a locking bolt can be passed and anchored in the bone, said locking bolt for static distal locking of the locking nail at the proximal end is inserted and for dynamic distal locking of the locking nail to the distal end of the elongated transverse hole. Thus, the aforementioned construction allows both static distal locking of the locking nail and dynamic distal locking of the locking nail.

p0009Preferably, the at least two cross holes are constructed as elongated transverse bores, so that a stable fixation of the locking nail is made possible on the bone according to claim 2nd

p0010According to the locking pins comprise a self-tapping thread with minimal thread depth, which is just enough to keep the locking pin in the bone. A tightening of the locking pin in the manner of a screw according to the invention is not provided. On the contrary, such a tightening is to be avoided according to the invention, since it has been found that this very often arise vulnerabilities for future fracture. The maintenance of the locking bolt according to the invention in the bone to be just so large that a slipping of the locking pin is prevented intramedullary nail for locking with respect.

p0011For the introduction of the locking bolt at both the proximal end and the distal end of the elongated transverse bores these ways according to claim 4 preferably a length which corresponds approximately to twice the diameter of the associated locking bolt. In principle, a slightly smaller or larger axial extent of the elongated transverse bores is also conceivable.

p0012The elongated transverse bores in the distal region of the locking nail should also be mentioned that a static distal locking usually at normal running neck fractures or fractures of the trochanteric region (from the top lateral to medial in according to the types A1 and A2 of the AO classification pertrochanterer fractures) is carried out. A dynamic distal locking is done for example in a transverse fracture of type A3 or substrochanteren fracture.

p0013The distal locking bolt according to the invention should also be introduced in accordance with claim 5 by means of a target device, said in the elongated transverse bores for positioning the locking bolt a reversible by 180 ° positioning tube with a hole corresponding to the diameter of the locking pin.

p0014Specifically, such a target device in claim 6 is described. It ranges from a single target device for both the right and the left side of the patient. The target device is connected to the proximal end of the locking nail to form a rigid connection therewith. The connection is made either by a screw or by a latching connection. Furthermore, care should be taken that the target device without long lever arms manages to avoid deforming it by touching on a lateral handle. Furthermore, the target device should be integral to avoid relative movements between parts of the target device, which could lead to deviations from predetermined targets (position of the femoral-neck blade on the one hand and position the distal locking elements on the other hand). It must be ensured the accuracy of the system.

p0015For the positioning of the distal locking elements, particularly locking bolt, has target device according to the invention at an approximately parallel to the locking nail and toward its distal end extending arm assigned in the assembled state with at least one of the at least one formed in the distal region of the locking nail elongated transverse hole long hole for receiving a complementary target rifle, which has at its one end a bore whose inner diameter is slightly larger than the outer diameter of a bore to be passed through by these distal locking bolt. The positioning tube is within said elongated hole 180 ° reversible, so that a hole in the target box, either the proximal or the distal end of the associated elongated transverse bore in the distal region of the locking nail is undeliverable. The positioning tube is blocked by positioning the aforementioned slot of the target device by means of a locking screw or the like.

p0016An embodiment of an inventively embodied osteosynthesis aid is explained in more detail in the accompanying drawings. Show it:<dl id="dl0001"><dt>Fig. 1</dt><dd>an inventively embodied locking nail in lateral view; </dd><dt>FIG. 2</dt><dd>the locking nail of Figure 1, partly in longitudinal section, partly in view.</dd><dt>Fig. 3</dt><dd>a plan view of the proximal end of the locking nail in the direction of arrows AA in Figure 2 and on an enlarged scale; FIG.</dd><dt>Fig. 4</dt><dd>a the locking nail according to Figures 1-3 associated femoral-neck blade in side view.</dd><dt>Fig. 5</dt><dd>the lateral (distal) end of the femoral-neck blade according to FIG 4 in plan view.</dd><dt>Fig. 6</dt><dd>the medial (proximal) end of the femoral-neck blade according to FIG 4 in plan view and in an enlarged scale.</dd><dt>Fig. 7</dt><dd>the tread portion of the femoral-neck blade according to FIG 4 along the section line AA in Figure 4 and in enlarged scale..; and</dd><dt>Fig. 8</dt><dd>the association between locking nail, femoral-neck blade and associated target device relative to each other and relative to the femur in a schematic front view.</dd></dl>

p0017In Figs. 1 - 8, an osteosynthesis aid is 10 to supply subtrochanteric and pertrochanterer and femoral neck fractures with an insertable from proximal into the medullary canal of a femur 11 locking nail 12, of a distal portion with two elongated transverse bores 13 (see Fig. 8) for receiving a distal locking member, that the locking bolt, not shown, and a proximal portion 14 with an oblique passage opening 16, and having a laterally through the oblique passage opening 16 can be introduced into the femoral neck 17 and femoral head 18 femoral neck part in the form of a femoral neck blade 19 with rectangular basic cross-section shown. The distal region of the locking nail 12 is marked with the reference number 15th

p0018According to the cross-section of the femoral-neck blade 19 of the cross section of the inclined through hole 16 is formed, femoral-neck blade 19 and through hole 16 are sized relative to each other that the femoral-neck blade 19 is held without play within the through hole 16th In the proximal end 20 of the locking nail 12, a not shown locking pin (set screw or the like.) can be used, namely screwed. The corresponding threaded hole is marked in Fig. 2 by the reference numeral 21. By means of the screwed into the threaded bore 21 of the locking pin, the axial movement of the femoral neck blade 19 within the oblique passage opening 16, either restricted or completely blocked. For this purpose, the through hole 16 associated with section 22 (see Fig. 4) of the femoral neck blade 19 on at least at the proximal (in the embodiment shown here, also at the distal) side an axially parallel groove 23, into which the in the proximal end 20 the locking nail 12 male lock element or the aforementioned locking pin engages in the manner described. The groove 23 may additionally comprise spaced axially spaced recesses 24 into which to engage the locking pin if necessary, to establish a secure connection between rigid locking nail 12 and femoral-neck blade 19 can. This should be 19 reliably avoided if necessary axial movement of the femoral-neck blade. Depending on requirements, either the axial groove 23 with the trough-shaped recesses 24 or the axial groove is in the femoral-neck blade 19 shown in FIG. 4 without the aforementioned 23 wells associated with the locking pin. The former association is particularly selected when the femoral-neck blade 19 is to be blocked within the oblique passage opening 16 of the locking nail 12th In this respect, the embodiment is double functionally in FIG. 4.

p0019As already mentioned, the neck portion is formed in the embodiment described here as a femoral neck blade 19 to one of a circular or rotationally symmetrical cross-section differing cross-section, namely a rectangular cross-section. a permanently rotationally fixed placement of the femoral-neck blade 19 is achieved within the slanted passageway 16 This and the corresponding cross-section of the oblique passage opening 16 in the locking nail 12th The rectangular through hole 16 is formed so that the femoral neck blade 19 is vertically placed in the through hole sixteenth The flat sides of the femoral-neck blade 19 therefore extend parallel to the longitudinal axis of the locking nail 12 and femoral neck. The described construction leads to a particularly great bending resistance of the femoral neck blade with the result that there is no risk for blocking of the axial movement of the femoral neck blade 19 due to bending is the same. With dynamic placement of the femoral-neck blade 19 within the through hole 16 by maintaining the momentum safely.

p0020As shown in FIG. 2 can be removed, the locking nail 12 is hollow throughout formed (through hole 25), so that it can be inserted through a not illustrated but known guide wire in the proximal femur. The wall thickness of the hollow locking nail 12 is about 1.5 to 2.5 mm, in particular about 2.0 mm. Moreover, the locking nail of a human-compatible material, in particular titanium or a titanium alloy. The same applies to the femoral-neck blade 19 and all other components such as femoral neck blade locking pin and distal locking bolts.

p0021.. Further, as the Figure 2 and of Figure 8 can be removed, is in the plane defined by the locking nail 12 and femoral neck blade 19 level, the proximal portion 14 of the locking nail 12 relative to the distal portion 15 by about 4 ° - 8 °, particularly about 6 ° laterally bent outwards, the transition between the distal and proximal portion by a kink-free curved section is formed 26th

p0022Incidentally, the locking nail 12 in the illustrated embodiment has a rotationally symmetric or circular cross-section. In principle, an oval cross-section is also conceivable in order to promote the rotation stability of the osteosynthesis aid within the femur.

p0023At the locking pin for the femoral neck blade 19 not shown in detail, it should be noted that this sunk in a conventional manner in the proximal end 20 of the locking nail 12 is arranged.

p0024To 12 increase the strength of the locking nail in the critical area of ​​the through hole 16, this area is widened in relation to the distal portion 15 of the locking nail 12th Specifically, the outer diameter of the locking nail 12 in the region of the passage opening 16 is about twice as large as the diameter of the distal portion 15. This ensures that the above-mentioned wall thickness of the locking nail 12 is obtained also in the region of the passage opening sixteenth The risk of breakage of the locking nail 12 in the region of the passage opening 16 is excluded in this way.

p0025Incidentally, all the transitions between the distal portion 15 and a widened proximal portion should be 14 without kinks or gently curved design to avoid stress peaks in said transition regions.

p0026According to the Fig. 1 -. 3, in particular according to Figure 3 are at the proximal end 20 of the locking nail 12, three evenly distributed over the circumference are arranged notches 27 are formed for positive connection with complementary projections on a target device, as in Figure 8 with the. reference numeral 28 is indicated. Through this positive connection, which is also combined with a non-positive screw (bolt 29 in Fig. 8 and corresponding threaded hole 30 in the proximal end 20 of the locking nail 12 as shown in FIG. 2), a rigid connection between the target device 28 and locking nail 12 is obtained which is required to position the femoral-neck blade 19 and distal locking bolt can precisely.

p0027The longitudinal axis 31 of the oblique passage opening 16 for the femoral neck blade 19 with the longitudinal axis 32 of the proximal portion 14 of the locking nail 12 at an angle α of either 125 ° or alternatively 135 °. These two angles can master all the physiological variations of the femoral neck Fermurschaft angle. A pronounced Valgisationsstellung to 140 ° and more is in the inventive system that is not dependent on a bony cortical force transmission is not required. Accordingly, only two target sheets are required when using the osteosynthesis aid, namely a target return for 125 ° and a further target sheet for 135 °. So it calls for a minimum number of instruments.

p0028The femoral-neck blade 19 has as shown in FIG. 8 at its outer, the femoral head 18 remote from the end of a radially projecting shoulder in the form of a circumferentially extending collar 33 which limits the lateral introduction of the femoral-neck blade 19 in the oblique passage opening 16 of the locking nail 12. This radially projecting shoulder or collar 33 may also be implemented with success in conventional femoral neck screws in order to avoid the above-mentioned risks when driving the femoral-neck blade or femoral neck screw. So it is a separate and important for practical design feature.

p0029According to FIGS. 4, 6, 7 and 8 is anchored in the femoral head 18 and femoral neck 17 section 34 of the femoral-neck blade 19 as double T or I-profile 35 known with a central through hole 36 for a not shown in detail, but in itself guidewire formed. The front lying in the femoral head 18 edges of the profile section 34 are constructed as a chisel-like cutting edges 37 to facilitate the turning of the femur neck blade 19 in the cancellous bone of the femoral neck and the femoral head without previous drilling of the cancellous bone to full width of the femoral neck blade. As already mentioned, 34 achieved with the described construction of the femoral-neck blade 19 with a double-T or I-profile section an extremely high moment of inertia and thus extremely high rigidity with minimal cross-sectional area, so that only the turning of the femoral-neck blade in the femoral neck and the femoral head little spongiosa must be displaced. In addition, the profile section 34 promotes the rotational stability of the femoral head and neck of the femur in relation to the femur feeding a femoral neck fracture or trochanteric fracture.

p0030The two distal transverse bores 13 in the distal region of the locking nail 12 are formed as an elongated hole transverse bores, are feasible for anchoring in the femur through which distal locking elements, namely locking bolt, said locking bolt for static distal locking of the locking nail 12 at the proximal end (in Fig. 1 and 2 the upper end) and for dynamic distal locking of the locking nail 12 at the distal end (to be introduced in Fig. 1 and 2 the lower end) of the elongated transverse bores 13. In the illustrated embodiment, the elongated transverse bores 13 each have an axial extension or length which corresponds approximately to 2.5 times the diameter of the associated locking bolt, or the width of the elongated transverse bores thirteenth

p0031The distal locking bolts are introduced by means of a target device 28th As already stated above, the distal locking bolt should have at their distal ends a self-tapping thread with minimal thread depth. The thread should be just enough to keep the locking pin in the femur bone. A clamping screw should not be possible to protect the bone as opposed to the prior art.

p0032The average diameter of the locking nail according to the invention is about 11 to 14 mm, preferably about 12 mm. This relatively small diameter is sufficient, since no force transmission from locking nail takes place on the bone, or to be held. The force is introduced via the femoral-neck blade, the intramedullary locking nail to the distal locking elements and from there to the distal Fermur. A large rigid locking nail which would make a bone contact to Fermur, would only be detrimental. There is the risk that the Fermur is blown through the nail, as well as increased risk of fracture at the end of the nail.

p0033With reference to FIG. 8 it is pointed to a suitable for the described osteosynthesis aids target device with the reference number 28. This is at the proximal end 20 of the locking nail 12 can be connected to form a rigid connection therewith. It has, at one in the assembled state approximately parallel to the locking nail 12 and towards the distal end at least one of the at least one formed in the distal region of the locking nail 12 elongated transverse bore 13 associated with slot 38 for receiving a complementary positioning tube 39 which at its one end comprises a bore 40 whose inner diameter is slightly larger than the outer diameter of a bore to be passed through by these distal locking bolt. The positioning tube 39 is reversible by 180 ° in the slot 38 so that the bore 40 either the proximal or the distal end of the associated elongated transverse hole 13 in the distal region of the locking nail 12 is deliverable. The ability to target rifle in the manner described to turn 39 by 180 °, is indicated in Fig. 8 with the double arrow 41. The bore 40 serves as a drill sleeve for a drill, with which the receiving holes in the femur for distal locking bolts are pre-drilled. In extension of the femoral-neck blade 19 has the aforementioned arm 42 a passageway for receiving a drilling and centering for the femoral-neck blade on. These two tubes are illustrated in FIG. 8, not in detail since it is known in this regard to construction elements per se.

p0034With this target device the femoral neck blade is further inserted, the corresponding area is drilled in the femoral neck and Fermurkopf, by means of a step drill, the front diameter of about 3.5 mm and in the rest of about 10 mm, wherein the area with a diameter of 10 mm for boring the accommodation space for the lateral (distal) portion of the femoral-neck blade is used. For the medial (proximal) profile-section of the femoral-neck blade a pilot hole is sufficient with a diameter of about 3.5 mm. The reaming via a target wire for the femoral-neck blade.

p0035Otherwise, the target device 28 is integrally formed to avoid relative displacements of individual components of the target device. Thus, a high accuracy for the insertion of the femoral-neck blade and the distal locking bolt is achieved by connecting the locking nail 12th

p0036If all design features of the system described united, obtained compared with the prior art optimal osteosynthesis aids such first attempts by the inventor have already shown.

p0037The foregoing finally let even realize that when using the osteosynthesis aid according to the invention, a minimum number of tools needed, namely:<ul><li>Target device 125 °;</li><li>Target device 135 °;</li><li>Drilling and centering for the femoral-neck blade;</li><li>Drilling and positioning tube for the distal locking bolt;</li><li>Target wire for the femoral-neck blade (diameter about 3.0 mm), with an associated impactor for femoral-neck blade, a screwdriver for the distal locking bolt and for the femoral-neck blade associated locking pin (set screw).</li></ul>

p0038All features disclosed in the application documents are claimed as essential to the invention insofar as they individually or in combination, over the prior art are new.