WO2018064779A1

WO2018064779A1 - Modular osteosynthesis implant assembly

Info

Publication number: WO2018064779A1
Application number: PCT/CH2016/000128
Authority: WO
Inventors: Pietro Regazzoni
Original assignee: Suratec Gmbh
Priority date: 2016-10-04
Filing date: 2016-10-04
Publication date: 2018-04-12

Abstract

A modular osteosynthesis implant assembly (1 ) for internal stabilization of a fractured target bone, comprising: an elongate bone plate (10); a plate insert (30) attachable to the elongate bone plate (10) having a base portion (31 ), a first hollow protrusion (34) with a central axis 'C2' and a second hollow protrusion (35) with a central axis 'C3', said protrusions (34,35) are sized and shaped to glideably receive each a primary bone anchor (60); and a locking mechanism for the locking of said plate insert (30) to said elongate bone plate (10; wherein said elongate bone plate (10) comprises at said first end (11) means sized and shaped for engagement with said plate insert (10), and wherein in the engaged state of the plate insert (10), the two protrusions (34,35) are arranged such their central axis 'C2' and 'C3" define a sagittal plane, P2"; and said two central axis 'C2' and 'C3" being spaced from each other by a distance X larger than 9 mm and preferably smaller than 13 mm.

Description

Modular osteosynthesis implant assembly

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a modular osteosynthesis implant assembly according to the preamble of claim 1 , a method for open or minimally invasive stabilization to promote an osteosynthesis according to the preamble of claim 23, and a kit for assembling the modular osteosynthesis implant assembly according to the preamble of claim 24.

2. Description of the Related Art

Hip fractures are a very common injury. The number of annual hip fractures is increasing worldwide. Especially the elderly population suffers from hip fractures. Due to the increasing number of elderly people, the annual number of hip-fractures is increasing fast.

One reason for a hip fracturing is osteoporosis. With rising age, the bones become more brittle and fracture more easily after a fall.

There are many types of hip-fractures, which need an individual treatment. For example, a femoral neck fracture in a patient with degenerated joint cartilage is preferably treated with a hip implant, completely replacing the joint. Fractures in younger patients with good quality cartilage are preferably treated with methods that reconstruct and maintain the joint.

Several methods of treatment are available depending on the location of the fracture around the hip, the number of bone fragments, the quality of the bone, and the size of the bone. Treatment methods vary from the insertion of two or more (cannulated) screws to the insertion of intramedullary nails to stabilize the bone fragments.

Another common method is the implantation of a sliding hip screw. The sliding hip screws consist of a plate (with a barrel) which is fixed to the lateral cortex of the femoral bone, and one or more large screws extending through the barrel from the plate into the femoral head. The screw can glide (telescope) within the plate barrel, therefore some types are called "dynamic". This gliding capacity (dynamic fixation) allows the femoral head-and-neck fragment - in case of a lack of medial buttress - to set itself laterally against the femoral shaft until a new buttress results. With implants without telescoping feature, there is a high risk of cut out of the screws or fatigue of the implant due to cyclic loading. After such complications often difficult reoperations, and total joint replacements are necessary. Telescoping implants are therefore the preferred implants for femoral fractures in this region. They allow early mobilization and full weight bearing, as the elderly patients mostly are not capable to bear weight partially. Shortening due to telescoping as well as lateral protrusion of the screws might cause local irritation. These disadvantages are irrelevant compared to the risks of rigid implants (cut-out and implant fatigue)

The lateral cortex of the femoral bone has to be prepared for the insertion of the barrel of the plate and the plate-barrel-junction. This causes a certain soft tissue damage. In many surgical fields important efforts have been made in order to reduce the additional soft tissue damage caused by the operation. (Minimal invasive surgery) These efforts comprise both changes of the surgical access and the implants.

What is therefore needed is an improved osteosynthesis implant assembly. BRIEF SUMMARY OF THE INVENTION

It is an object of the invention to provide an osteosynthesis implant assembly and surgical technique which allows a sliding (dynamic) hip screw implant to be implanted in a minimally invasive manner, providing at least equivalent stability as commonly available monoblock or monolith implants.

The invention solves the posed problem with a modular osteosynthesis implant assembly comprising the features of claim 1 , with a method for open or minimally invasive stabilization to promote an osteosynthesis according to claim 23, and a kit for assembling the modular osteosynthesis implant assembly according to claim 24.

The advantages of the modular osteosynthesis implant according to the invention are the following:

- The bone plate and the plate insert are separate element which can be assembled in situ and therefore allow a minimally invasive surgery avoiding a possible damage to soft tissues; and - Possibility to optionally use a trochanter fixation plate attachable to the modular osteosynthesis implant assembly according to the invention.

The inventive osteosynthesis implant assembly for fixation of fractures in the metaphysis area is a modular implant to facilitate minimal invasive implantation, which can be assembled "in situ" within the body of the patient at the site of the fractured target bone. By in-situ assembly of the implant, the individual parts require less soft tissue distraction or a smaller incision size, which benefits the recovery of the patient. After assembly of the modular osteosynthesis implant assembly the elongated bone plate, the plate insert and the locking element form one integral bone plate unit. This integral bone plate unit provides the same functionality as common monoblock or monolith implants, used for the treatment of the target indications.

The elongated bone plate has a first end and an opposite second end, defining a first central axis 'C along the length of the elongated bone plate. At said first end, intended for placement against the metaphysis area of the target bone, an opening extends through the thickness of the elongated bone plate, and has length 'XV. Length 'X1 ' may be substantially equal to the thickness of the elongate bone plate at its first end. Preferably the opening is completely surrounded by the material of the bone plate, but alternatively can also comprise a gap extending to the outside of the elongated bone plate.

Furthermore the elongate bone plate comprises at least one throughbore or elongated hole, configured to receive secondary bone fasteners. Said throughbore or elongated hole is located between said opening and said second end of the plate.

Furthermore, the elongate bone plate comprises at least one channel, sized and shaped to lockingly seat at least one locking element. The channel that receives the locking element intersects with the opening that receives the plate insert. The locking element is intended to rigidly fixate the plate insert into the elongated bone plate, and so form the integral plate unit, as described later. In a preferred embodiment the channel comprises an internal thread and is oriented under an acute angle 'a' to the first central axis 'C of the elongated bone plate. Additionally the elongate bone plate comprises an attachment feature for the assembly of said bone plate to a targeting device. A targeting device facilitates speed, accuracy and minimal invasiveness of insertion of the primary and secondary bone anchors. Furthermore the targeting device provides guidance in the bone bed preparation steps, and provides guidance in assembly steps to mount the individual components of the integral bone plate unit. In a preferred embodiment the attachment feature is configured as a second internal thread, combined with a pocket arranged at the first end of the elongate bone plate.

Alternatively the attachment feature is configured as a second internal thread combined with at least one dent.

The opening at the first end of the elongate bone plate is configured to mate with and seat the plate insert. The plate insert comprises a base with at least one hollow protrusion extending therefrom. The hollow protrusion is shaped and sized to receive a primary bone anchor, and therefore extends completely through the plate insert. In an alternative embodiment the plate insert comprises two hollow protrusions; therefore the integral bone plate unit is intended to be used with two primary bone anchors. By usage of at least two anchors the target bone fragment is fixated in compressive direction, tensile direction, and furthermore against rotation. In a preferred embodiment the protrusion is shaped as at ieast one tubular protrusion. The tubular protrusion is intended to be countersunk inside the target bone, and therefore for preparation of the bone bed in the target bone, one or more holes can be drilled or reamed. In an alternative embodiment the protrusions can have any shape, such as a quadratic, oblong, round or oval shape. The bone bed preparation may be done by usage of a small reamer or a punching system. Alternatively oscillating saws can be used.

In a preferred embodiment, said two hollow protrusions are spaced from one another at a distance wherein the outer walls of the protrusions are spaced at a distance of less than 5 mm. Most preferred the protrusions almost or minimally intersect and are connected by a rib. A rib provides a larger stability by connecting the individual tubular protrusions.

Depending on the indication the axis of the tubular protrusions need to be oriented under an anatomy matching angle in relation to the first central axis 'C of the elongated plate. Exemplary angles for the application as a femur osteosynthesis device are angles between 90° and 150°.

Furthermore the plate insert comprises a recess sized and shaped to mate with said locking element, and additionally coinciding with said hole of said elongated bone plate.

Furthermore the osteosynthesis implant assembly comprises a locking element The locking element is shaped to rigidly fixate the plate insert into the elongated bone plate, and so form the integral plate unit.

In a preferred embodiment the locking element is shaped as a bolt with an externally threaded head including drive geometry. The drive geometry is configured to engage with a screwdriver or similar. By screwing in the locking element, wherein the external thread engages into an internal thread of the elongated bone plate, the locking element simultaneously forms an interface with the elongate bone plate and the plate insert. This interface inhibits the plate insert from disengaging from the elongated bone plate. In a preferred embodiment the locking element is inserted substantially parallel to the plate longitudinal axis. This engagement direction facilitates a preferred surgical insertion direction, furthermore most effectively transfers loads within the assembly. When implanted, for example when used for fixation of a femoral neck fracture, the osteosynthesis implant assembly must withstand loads that are higher than the full bodyweight.

The primary bone anchor is intended to fixate the fractured bone in the epiphysis area. In a preferred embodiment the primary bone anchor is a bone screw. Alternatively the primary bone anchor can be a pin shaped element, a bolt, a helical blade, and etcetera. In a preferred embodiment said primary bone anchor is an externally threaded screw comprising a smooth shaft portion with a diameter Γ, an externally threaded tip portion and a head portion comprising a second drive geometry. Preferably the external thread partially extends from said tip toward said head portion and end is a first transition region. Said first transition region may have a smaller diameter than diameter 'D1 ' of said shaft portion. Furthermore the primary bone anchor may comprise a second transition region wherein the threaded tip merges into the smooth shaft portion. Furthermore the primary bone anchor comprises a circumferential rim and clearance groove in said smooth shaft portion. This rim is intended to form a stop or a seat to limit the telescoping distance of the primary bone anchor within the plate insert, by seating against said tubular protrusion.

The secondary bone anchor is intended to fixate the integral bone plate unit against the shaft of the target bone in the metaphysis and/or diaphysis area of the target bone. The secondary bone anchor may be configured as a bone screw, dowel, bolt, pin, locking- screw or cerclage wire.

In a further embodiment the osteosynthesis implant assembly is part of a kit comprising elongated bone plates of different lengths comprising different numbers of throughbores and elongated holes, furthermore comprising plate inserts having said different anatomical angles. Further kit components are locking elements and primary and secondary bone anchors of different anatomical lengths.

In another embodiment a trochanter fixation plate can be attached to the integral bone plate unit. The trochanter fixation plate 90 is configured as a frame with at least one arm extending thereof. Said arm comprises at least one screw receiving fixation unit, wherein screw receiving fixation units are linked by a thinner connectors to said frame. The thinner connectors allow manual bending and shaping of the trochanter fixation plate for adaptation to the anatomic shape of the trochanteric bone, and furthermore to individual direct the trochanter fixation screws to most effectively fixate and stabilize the fractured trochanteric bone.

In a preferred embodiment the individual components of the osteosynthesis implant assembly are made of biocompatible materials such as titanium, titanium alloys, cobalt chromium alloys, stainless steel, or combinations thereof, and may comprise coatings to prevent ongrowth or ingrowth, or provide better sliding or articulation properties.

In a special embodiment the central axis 'C2' and ^*C3' of the first and second hollow protrusions of the osteosynthesis implant assembly are parallel. This embodiment allows optimal properties for the telescoping action of the bone anchors to be glideably received in the protrusions.

In another embodiment the central axis 'C2' and 'C3' of the first and second hollow protrusions are divergent, preferably by an angle of ± 3°.

In a further embodiment the first hollow protrusion has the shape of a hollow circular cylinder with an inner diameter di and the second hollow protrusion has the shape of a hollow circular cylinder with an inner diameter d₂.

In a special embodiment is di = d₂.

In a further embodiment the means at the first end of the elongate bone plate sized and shaped for engagement with the plate insert are designed in form of an opening extending completely through said bone plate for a length of "X1 " corresponding to the thickness of the bone plate in the region of the opening.

In a further embodiment the plate insert has a length Ή1 ', wherein length Ή is larger than said length 'XV and preferably in the range of 1 .1 'Χ1 ' < Ή1 ' < 3.0 'XV.

In another embodiment said two hollow protrusions have a tubular shape with outer walls, wherein said outer walls are connected by a rib.

In a further embodiment said locking mechanism comprises at least one locking element at said first end and at least one channel intersecting with said opening sized and shaped to lockingly seat said at least one locking element.

In a preferred embodiment said locking element comprises at least partially an external thread for a threadedly engagement of said locking element in said elongate bone plate.

In a further embodiment the plate insert comprises at least one recess sized and shaped for engagement with at least one locking element, to lockingly mate with said locking element, wherein when assembled inside said elongated bone plate, said first channel and said recess coincide and align. In another embodiment said elongate bone plate comprises at least one through bore and/or elongated hole, configured to receive at least one secondary bone anchor, such as a bone screw, dowel, bolt, pin, locking-screw or cerclage wire.

In a further embodiment the osteosynthesis implant assembly comprises primary bone anchors g!ideably received in said protrusions. in a further embodiment said primary bone anchor is an externally threaded screw with a smooth shaft portion with a diameter 1 ', a tip portion and a head portion, wherein said thread partially extends from said tip to said head portion, furthermore comprises a circumferential rim of third diameter 'D3' on said smooth shaft portion, wherein said rim forms a seat to limit the telescoping distance of said primary bone anchor.

In another embodiment said hollow protrusion of said plate insert has an inner second diameter 'D2' extending through said plate insert, wherein said diameter 2' > 1 " > 'D3' and upon loading of said tip portion of said primary bone anchor, said rim hangs over the hollow protrusion end.

In a further embodiment the first end of said elongate bone plate comprises an attachment feature for assembly of said bone plate to a targeting device to facilitate the placement of said elongate bone plate onto said target bone and guide the insertion of said plate insert, and/or primary bone anchor and/or secondary bone anchor and/or said eventual locking elements.

In a further embodiment the modular osteosynthesis implant assembly comprises a buttress element, preferably in the form of a trochanter fixation plate attachable to said first end for fixation and stabilization of additional fracture fragments. in a preferred embodiment the buttress element is not attached to said first end but rather an integral part of said elongate bone plate at said first end. In a further embodiment the buttress element comprises at least one arm with at least one screw receiving fixation unit, sized and shaped to be inter-operatively bend to seat flush against the target bone.

In a special embodiment the modular osteosynthesis implant assembly is to be used for the treatment of proximal femur fractures in open surgery or minimal invasive surgery.

In a further embodiment the modular osteosynthesis implant assembly is to be used for the treatment of split-off trochanter bone fragments.

In a further embodiment said two tubular protrusions are spaced from one another at a distance 'K' smaller than 5 mm.

A method for open or minimally invasive stabilization to promote an osteosynthesis, by use of the modular osteosynthesis implant assembly according to the present invention comprises the following surgical steps,

- Reduction of the fracture

- performing a small incision near the epiphysis of the target bone

- preliminary fixation of the fragments with K wires

- Insertion of the elongate bone plate with attached aiming device

- Placement of at least one central K-wire preferably representing the central axis of at least one primary bone anchor

- Initial fixation of the elongate bone plate against the target bone

- Drilling of for bone bed preparation for the countersunk placement of the plate insert

- Pre drilling for the placement of the primary bone anchors

- Insertion of the plate insert

- Fixation of the plate insert with said locking elements

- Insertion of the primary bone anchors

- Insertion of the remaining secondary bone anchors

- Removal of all instruments. A kit for assembling the modular osteosynthesis implant assembly according to the present invention comprises elongate bone plates of different lengths comprising different numbers of through bores and elongated holes, furthermore comprising plate inserts having different anatomical angles a, furthermore said kit comprising different primary bone anchors and secondary bone anchors of different lengths and potentially locking elements of different lengths.

Brief description of the figures:

Figure 1A depicts a perspective view each of an embodiment of the osteosynthesis implant assembly according to the invention in an assembled configuration;

Figure 1 B illustrates an exploded view of the embodiment of the osteosynthesis implant assembly of fig. 1A without the trochanter fixation plate;

Figure 2A illustrates a perspective view of the elongate bone plate according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1 B;

Figure 2B illustrates a lateral view of the elongate bone plate according to the embodiment of the osteosynthesis implant assembly of figs. 1 A and 1 B;

Figure 2C illustrates a top view of the elongate bone plate according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1 B;

Figure 2D illustrates a front view of the elongate bone plate according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1 B;

Figure 2E illustrates a sectional view of the elongate bone plate along line A - A in fig. 2D; Figure 3A depicts a perspective view of the plate insert according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1 B;

Figure 3B illustrates a lateral view of the plate insert according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1B;

Figure 3C illustrates a front view of the plate insert according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1B;

Figure 3D illustrates a sectional view of the plate insert along line B - B in fig. 3C;

Figure 3E depicts a cross sectional view illustrating the orientation of the primary bone anchor in relation the central axis of the elongated bone plate according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1 B;

Figure 4A depicts a perspective view of the locking element according to the embodiment of the osteosynthesis implant assembly of figs. 1 A and 1 B;

Figure 4B depicts a perspective view of the locking element in engagement inside the recess of the plate insert according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1B;

Figure 4C illustrates a lateral view of the elongate bone plate with the plate insert according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1 B;

Figure 4D depicts a cross sectional view along line C - C in fig. 4C;

Figure 5 depicts a side view of the primary bone anchor according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1B; Figure 6A and 6B depict the iimited telescoping principle wherein the circumferential rim of the primary bone anchor seats against the plat insert according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1 B;

Figure 7 depicts an exploded view of the embodiment of the osteosynthesis implant assembly of fig. 1 A including the trochanter fixation plate;

Figure 8A depicts a perspective view of the elongate bone plate according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1 B attached to a targeting device;

Figure 8B illustrates a longitudinal section of the elongate bone plate according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1 B attached to the targeting device of fig. 8A;

Figure 9 depicts a perspective view of a secondary bone fixation element according to the embodiment of the osteosynthesis implant assembly of figs. 1A and 1B used for fixation of the plate against the shaft portion of the target bone.

Detailed description of the invention:

In reference to figure 1A an osteosynthesis implant assembly 1 is shown in an assembled configuration, comprising the elongate bone plate 10, the plate insert 30, two locking elements 50, one or two primary bone anchors 60, and an optional trochanter fixation plate 90. The elongate bone plate 10, the plate insert 30, two locking elements 50 form said integral bone plate unit 2.

Referring to figure 1 B, the osteosynthesis implant assembly 1 is shown in an exploded view, without trochanter fixation plate 90.

In reference to figures 2A - 2E the elongate bone plate 10 is shown in greater detail. Said elongate bone plate 10 has a first end 1 1 and a second and opposite end 12. A virtual line connecting said first end 1 1 and second end 12 forms the first central axis 'C along the length of the elongated bone plate 10. Through this axis, two substantially perpendicular planes are shown, namely a frontal plane 'Ρ and a sagittal plane 'P2'. The elongated plate 10 as shown in figures 2A - 2E is a straight plate. Alternatively the plate may be a slightly anatomically curved plate. Curvatures might be in the frontal plane 'P1 ' and/or in the sagittal plane 'P2' of the elongated bone plate 10.

Furthermore the elongate bone plate comprises an opening 13 at its first end 1 1 . This opening is sized and shaped to receive plate insert 30 and has depth 'XV. Consequently depth 'XV equals the thickness of said elongate bone plate 10 in the opening area. In one embodiment the opening 13 is shaped as a long hole. Alternatively the opening 13 can have any shape, such as a quadratic, oblong, round or oval shape. Said opening 13 Is completely surrounded by plate material. In an alternative embodiment the opening 13 might be open to the side or first end 1 1 of the elongated bone plate 10.

Additionally, in the region between the opening 13 and a first throughbore 18 of the elongate bone plate 1 0, an attachment feature 14 (Fig. 8B) is present. Attachment feature 14 is configured for engagement with a targeting device 100 (Figs. 8A and 8B). A targeting device facilitates speed, accuracy and mirimal invasiveness of insertion of the primary and secondary bone anchors 80 (Fig. 9) and for preparation of their bone beds. Said attachment feature 14 is configured as a second internal thread 15. Additionally, the elongate bone plate 10 comprises a pocket 22 adjoining the opening 13 at the first end 1 1 of the elongate bone plate 10 (Fig. 8B). The second internal thread 15 allows for a rigid fixation of the targeting device 100 to the elongated bone plate 1 0, wherein the pocket 22 fixes the orientation of the targeting device 100 in relation to the sagittal plane 'P2' of the elongated bone plate 10.

Furthermore, the elongate bone plate 10 comprises at least one first channel 16, sized and shaped to lockingly seat at least one locking element 50. The first channel 16 comprises a first internal thread 17 and is oriented under an acute angle ,α' (Fig. 2E) to the first central axis 'C of the elongated bone plate 10. In an alternative embodiment the first channel 16 is oriented substantially parallel to the first central axis 'C of the elongated bone plate 10. Said first internal thread 17 is located at the first end 1 1 of the elongated bone plate 10. In a preferred embodiment the first internal thread 17 extends approximately 6mm inside said channel 16. Alternatively the whole channel 17 comprises a first internal thread 17. In a preferred embodiment said channel 16 extends into the sidewa!ls 21 of said opening 13 throughout the full length of said opening 13. As a result, the locking elements 50 form a long interference fit with said plate insert 30 as described in greater detail later.

Furthermore the elongate bone plate 10 comprises at least one throughbore 18 or elongated hole 19, configured to receive secondary bone anchors 80 (Fig. 9). Said throughbore 18 or elongated hole 19 is located between said opening 13 and said second end 12 of the elongate bone plate 10.

The number of throughbores 18 and/or elongated holes 19 relates to the overall length of the integral bone plate unit 2. This length is related to the bone fracture pattern and bone quality of the patient. For example, for an isolated femoral neck fracture often shorter bone plates can be used, only comprising two throughbores 18 for the fixation against the shaft portion of the bone. The number and order of throughbores 18 and elongated holes 19 can vary per elongated bone plate 10. As shown in figures 2A - 2E, in an exemplary embodiment the elongate bone plate 10 comprises three throughbores 18 and one elongated hole 19 at the second end 12 of the elongate bone plate 10. Between the throughbores 18 and elongated holes 19 one or more cerclage grooves 20 are positioned. The cerclage grooves 20 can keep cerclage wires in place and prevent cerclage wires from slipping away over the elongate bone plate 10.

In reference to figures 3A - 3E the plate insert 30 is shown.

The plate insert 30 comprises a base portion 31 with at least one hollow protrusion 32, 33 extending therefrom. The hollow protrusions 32, 33 are shaped and sized to receive a primary bone anchor 60. The hollow protrusion 32 has an inner diameter 'D2' which extends completely through the plate insert 30, meaning extending through the base portion, likewise hollow protrusion 33 extends completely through the plate insert 30. The hollow protrusion 32 has a second central axis 'C2\ likewise the hollow protrusion 33 has a third central axis 'G3\ In an alternative embodiment the plate insert comprises two hollow protrusions 32, 33, therefore the integral bone plate unit 2 is intended to be used with two primary bone anchors 60 (Fig. 3E). By usage of at least two primary bone anchors 60 the target bone fragment in which the primary bone anchors 60 are screwed is fixated in a compressive direction, a tensile direction, and furthermore against rotation.

In a preferred embodiment said hollow protrusion 32, 33 has an inner diameter 2'. The combined height Ή1 ' of said base portion 31 and hollow protrusion 32, 33 preferably is at least 1.5 times diameter Ό2'. A large length-diameter ratio provides low friction between the interface between the primary bone anchor 60 and the plate insert 30. Low friction is necessary to allow the primary bone anchor 60 to slide or telescope within the plate insert 30. To lower friction, alternatively surface coatings or surface treatments can be used, such as Diamond-Like-Carbon, special anodized layers, surface polishing and/or combinations thereof.

Furthermore said plate insert comprises a hollow protrusion end 39.

In a preferred embodiment said hollow protrusions 32, 33 are shaped as tubular protrusions 34 and 35. The tubular protrusions 34, 35 are intended to be countersunk inside the target bone. In a preferred embodiment for the surgical method of implantation the preparation of the bone bed in the target bone is executed by drilling or reaming of one or more holes.

Said two tubular protrusions 34, 35 are spaced from one another at a distance 'K' wherein the outer walls 36, 37 of the hollow protrusions 32, 33 are spaced at a distance of less than 5 mm. Most preferred the hollow protrusions 32, 33 almost or minimally intersect. Furthermore the tubular protrusions 34, 35 may be connected by a rib 38. By connection through a rib 38 the combined construct has a larger stability and stiffness in comparison to the individual tubular protrusions 34, 35.

A short spacing, when connected by a rib 38 or when intersecting facilitates easier surgical bone preparation steps. When preparing the bone bed for the countersunk placement of the plate insert 30 by drilling two substantially parallel holes, no or little bone material between the tubular protrusions 34, 35 need to be removed.

The base portion 31 has a height Ή2'. Height Ή2' is substantially equal to said depth 'XV of opening 13. Referring to figure 3B, a cross-sectional view of the elongate bone plate 10 including plate insert 30 and primary bone anchors 60 is shown.

Depending on the indication the axis of the tubular protrusions 34, 35 need to be oriented under an anatomy matching inclination angle 'β' in relation to the first central axis 'C1 ' of the elongated plate 10. The tubular protrusions 34, 35 define the direction of the primary bone anchor 60 with fourth central axis 4'. Exemplary inclination angles 'β' for the application as a proximal femur osteosynthesis device are angles between 120° and 150°. Most common in monoblock bone plates angles are provided varying in 5° steps from 120° to 150° For the application as a distal femur osteosynthesis device for the fixation of condylar fractures, this angle may vary from 90° to 120°. In a preferred embodiment the axis of the tubular protrusions 34, 35 is oriented under an anatomy matching inclination angle 'β' in relation to the first central axis 'C1 ' of the elongated plate, between 90° and 150°.

Furthermore the plate insert 30 comprises at least one recess 40 sized and shaped to mate with said locking element 50. Recess 40 may be shaped as a first groove, but also may be shaped as a second channel. In a preferred embodiment, when said Insert 30 is assembled into elongate bone plate 10, said recess 40 coincides with said first channel 16 of said elongate bone plate 10. In a preferred embodiment the walls of the first channel 16 and recess 40 are substantially aligned. A perfect alignment facilitates a perfect simultaneous engagement of said locking element 50 with said elongate bone plate 10 and plate insert 30, and therefore the components of the integral bone plate unit 2 will have near to zero play in relation to each other and form a rigid unit.

Preferably said recess 40 extends over the total length of the base portion 31 of the plate insert 30.

Said recess 40 may be shaped circular or quadratic. For manufacturing reasons of said first channel 16 by drilling, and the intended perfect alignment of the recess 40 and the first channel 16, the recess 40 preferably is shaped as a first groove, defined by a constant radius 'R'.

Referring to figure 4a to 4D, the locking element 50 is depicted in greater detail, as well as the interaction with said elongate bone plate 10 and plate insert 30. The locking element 50 is sized and shaped to rigidly fixate the plate insert 30 into the elongated bone platelO, and so form the integral plate unit 2.

The locking element 50 is shaped as a bolt with an externally threaded head 51 including drive geometry 52. The drive geometry 52 is configured to engage with a screwdriver or similar. By screwing in the locking element 50, wherein the external threaded head 51 engages into the first internal thread 17 of the elongate bone plate 10, the locking element 50 simultaneously forms an interface with the elongate bone plate 10 and the plate insert 30. As shown in figures 4B and 4D, this interface inhibits the plate insert 30 from disengaging from the elongated bone plate 10. In a preferred embodiment the locking element 50 is inserted under said acute angle ,α' (Fig. 2E) to the plate longitudinal first central axis 'C1\ as described earlier. This engagement direction facilitates a preferred surgical insertion direction, and furthermore most effectively transfers loads within the assembly. The locking element 50 comprises a first shaft portion 53. Said shaft portion 53 is sized and shaped to fit into said first channel 16 and simultaneously seat into recess 40 of the plate insert 30, as depicted in figure 4B and 4D.

In an alternative embodiment the locking element is a rivet, a pin with a press-fit, a dowel, a fully threaded bolt, a screw, a split pin, or similar.

In a preferred embodiment to facilitate ease of manufacturing and ease of inter- operative assembly, the locking element 50 is shaped as a rotational symmetric locking element.

Locking element 50 furthermore comprises a chamfered or rounded tip 54 to facilitate ease of insertion and assembly.

Referring to figure 5, the primary bone anchor 60 is shown. Primary bone anchor 60 is intended to fixate the fractured bone in the epiphysis area. Exemplary fractures are proximal femur fractures, including femoral neck fractures, trochanteric and subtrochanteric fractures. Other exemplary fractures are condylar fractures of the distal femur or fractures of the proximal tibia plateau.

In a preferred embodiment the primary bone anchor 60 is a bone screw. Therefore said primary bone anchor 60 is an externally threaded screw comprising a smooth shaft portion 61 with a diameter Ό1 ', an externally threaded tip portion 62 and a head portion 63 comprising a second drive geometry 64. Preferably the external thread partially extends from said tip portion 62 toward said head portion 63 and located at its end is a first transition region 69, Said first transition region 69 may have a smaller diameter than first diameter 'D1 ' of said shaft portion 61 . Furthermore the primary bone anchor 60 may comprise a second transition region 65 wherein the first transition region 69 merges into the smooth shaft portion 61. The primary bone anchor 60 has a fourth central axis 'C4^!.

At the second transition region 65, the primary bone anchor 60 comprises a minimally enlarged rim 68 of third diameter 'D3\ followed by a circumferential clearance groove 66 in said smooth shaft portion 61. The difference in diameter of the minimally enlarged rim 68 may be only 0.1 mm larger than the diameter of the smooth shaft portion 61. The minimally enlarged rim 68 in combination with said clearance groove 66 is intended to form a stop or a seat 67 to limit the telescoping distance of the primary bone anchor 60 within the plate insert 30, by seating against said hollow protrusion end 39. In an alternative embodiment rim 68 is of substantially equal diameter as said smooth shaft portion 61. When substantially equal in diameter, said clearance groove 66 needs to be wide to allow said rim 68 to form said seat 67.

Referring to figure 6A and 6B, the stop principle is shown schematically. Figure 6A depicts the primary bone anchor 60 inside the integral plate unit 2 in a first configuration wherein the primary bone anchor 60 has not telescoped. Figure 6B depicts the primary bone anchor 60 inside the integral plate unit 2 in a second configuration wherein the primary bone anchor 60, after telescoping, is seating against the plate insert 30.

In detail, said primary bone anchor smooth shaft portion 61 may be sized and shaped to be slidingly and rotationally free engaged inside the hollow protrusion 32, 33. To allow the sliding and rotation, a minimal play may be required. During loading of the threaded tip portion 62, the primary bone anchor 60 can be oriented minimally obliquely inside the hollow protrusion 32, 33 of said plate insert 30. Hence the fourth central axis 'C4' of said primary bone anchor 60 and said second or third central axis 'C2', 'C3' of said hollow protrusion 32, 33 do not coincide. Furthermore inner diameter 'D2' is larger than the third diameter 'D3' of said minimally enlarged rim 68. As a result rim 68 hangs over the inside wall of the hollow protrusion 32, 34. Now, when telescoping into said plate insert 30, said rim 68 will seat against hollow protrusion end 39. Referring to figure 7, another embodiment of the invention is shown, namely a trochanter fixation plate 90 that can be attached to the elongate bone plate 10. The trochanter fixation plate 90 is configured as a frame 94 with at least one arm 95 extending thereof. Said arm 95 comprises at least one screw receiving fixation unit 91 , wherein screw receiving fixation units are linked by a thinner connectors 92 to said frame 94. In an exemplary embodiment said trochanter fixation plate 90 is configured to be connected to the first end 11 of the elongate bone plate 10. Therefore said trochanter fixation plate 90 comprises a base portion 93 located on the frame 94 at the end which contacts the first end 1 1 of the elongate bone plate 10 in the assembled state, wherein the base portion 93 has one or two holes 96 each suitable to pass a locking element 50 therethrough so that the trochanter fixation plate 90 can be affixed to the elongate bone plate 10 by means of the locking elements 50.

The thinner connectors allow manual bending and shaping of the trochanter fixation plate 90 for adaptation to the anatomic shape of the trochanteric bone, and furthermore to individual direct the trochanter fixation screws to most effectively fixate and stabilize the fractured trochanteric bone.

Referring to figures 8A and 8B the assembly of said elongate bone plate 10 to a targeting device 100 is shown. The targeting device comprises a sleeve 103 with at least one first targeting hole 101 and at least one second targeting hole 102.

The first targeting holes 101 penetrate the sleeve 103 at an acute angle with respect to the longitudinal axis 104 of the sleeve 103 and directly aim towards and are aligned with said one or more throughbores 18 or elongated hole 19 of said elongate bone plate 10. Furthermore, the first targeting holes 101 are sized and shaped to receive guiding sleeves that allow to prepare the bone with drills and reamers in a guiding manner. The second targeting hole 102 penetrates the sleeve 103 along the longitudinal axis 104 of the sleeve 103 and aims towards opening 13 of said elongated bone plate 10. The second targeting hole 102 is sized and shaped to pass drills and reamers which are guided by means K-wires 105 so that no additional guiding sleeves are necessary to prepare the bone with drills and reamers in a guiding manner. In a first step, the bone is prepared with drills and reamers in a guided manner by using guiding sleeves inserted into the first targeting holes 101 and by using K-wires 105 to guide the drills and reamers. Additionally the sleeve 103 and the guiding sleeves inserted in the first targeting holes 101 protect surrounding soft tissue from damage. For preparation of the bone bed for the primary bone anchors 60 and the plate insert 30, second targeting holes 102 are aligned with the intended position of the plate insert 30 in the elongate bone plate 10 and therefore also aligned with the intended direction of the primary bone anchors 60. The direction of the primary bone anchors 60 in relation to the first central axis 'C of the elongate bone plate 10 is defined by the axis of the hollow protrusions 32 and 33 of plate insert 30.

In a second step the targeting device 100 is used for a guided insertion of the primary and secondary bone anchors 60, 80. Thereby, the second targeting hole 102 in the sleeve 103 can directly be used for a guided insertion of the plate insert 30 and of the primary bone anchors 60 via guidance by means of the - wires 105, while the guiding sleeves inserted in the first targeting 101 can be used for a guided insertion of the secondary bone anchors 80.

Referring to figure 9 an exemplary secondary bone anchor 80 is shown, configured as a shorter bone screw. The secondary bone anchor is intended to fixate the integral bone plate unit 2 against the shaft of the target bone in the metaphysis and/or diaphysis area of the target bone. The secondary bone anchor 80 may be configured as a bone screw, dowel, bolt, pin, locking-screw or cerclage wire. The secondary bone anchor 80 is shaped and sized to engage into said throughbore 18 or elongated hole 19 of said elongate bone plate 10.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the scope of the appended claims.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Claims

CLAIMS:

1. A modular osteosynthesis implant assembly (1 ) for internal stabilization of a fractured target bone, comprising; a) an elongate bone plate (10), having a first end (1 1 ) and an opposite second end (12), a virtual central axis 'C extending through said elongate bone plate (10), and a frontal plane 'P1 ' in which said elongate bone plate (10) is lying; b) a plate insert (30) attachable to the elongate bone plate (10) having a base portion (31 ), a first hollow protrusion (34) with a central axis 'C2' and a second hollow protrusion (35) with a central axis 'C3', said protrusions (34,35) extending from said base portion (31 ), and being sized and shaped to glideably receive each a primary bone anchor (60); c) a locking mechanism for the locking of said plate insert (30) to said elongate bone plate (10); d) said elongate bone plate (10) comprising at said first end (1 1 ) means sized and shaped for engagement with said plate insert (10), and wherein e) in the engaged state of the plate insert (10), the two protrusions (34,35) are arranged such their central axis 'C2' and 3" define a sagittal plane 'P2" which is essentially orthogonal to said frontal plane 'Ρ1 '; and f) said two central axis 'C2' and 'C3" being spaced from each other by a distance X larger than 9 mm and preferably smaller than 13 mm.

2. Modular osteosynthesis implant assembly (1 ) according to claim 1 , characterized in that the central axis 'C2' and 'C3' of the first and second hollow protrusions (34,35) are parallel.

3. Modular osteosynthesis implant assembly (1 ) according to claim 1 , characterized in that the central axis 'C2' and 'C3' of the first and second hollow protrusions (34, 35) are divergent, preferably by an angle of ± 3°.

4. Modular osteosynthesis implant assembly (1 ) according to one of the claims 1 to 3, characterized in that the first hollow protrusion (34) has the shape of a hollow circular cylinder with an inner diameter di and that the second hollow protrusion (35) has the shape of a hollow circular cylinder with an inner diameter d₂.

5. Modular osteosynthesis implant assembly (1 ) according to claim 4, characterized in that d† = 02-

6. Modular osteosynthesis implant assembly (1 ) according to one of the claims 1 to 5, characterized in that the means at said first end (1 1 ) of said elongate bone plate (10) sized and shaped for engagement with said plate insert (10) are designed in form of an opening (13) extending completely through said bone plate (10) for a length of "X1 " corresponding to the thickness of the bone plate (10) in the region of the opening (13).

7. Modular osteosynthesis implant assembly (1 ) according to claim 6, characterized in that the plate insert (30) has a length Ή 1 ', wherein length Ή1 ' is larger than said length 'XV and preferably in the range of 1 .1 'XV≤ Ή1 ' < 3.0 'Χ1 '.

8. Modular osteosynthesis implant assembly (1 ) according to one of the claim 1 to 7, characterized in that said two hollow protrusions (34, 35) have a tubular shape with outer walls, wherein said outer walls are connected by a rib.

9. Modular osteosynthesis implant assembly (1 ) according to one of the claims 1 to 8, characterized in that said locking mechanism comprises at least one locking element (50) at said first end and at least one channel (16) intersecting with said opening (13), sized and shaped to lockingly seat said at least one locking element (50).

10. Modular osteosynthesis implant assembly (1 ) according to claim 9, characterized in that said locking element (50) comprises at least partially an external thread for a threadedly engagement of said locking element (50) in said elongate bone plate (10).

11. Modular osteosynthesis implant assembly (1 ) according to claim 9 or 10, characterized in that the plate insert (30) comprises at least one recess (39) sized and shaped for engagement with at least one locking element (50), to lockingly mate with said locking element (50), wherein when assembled inside said elongated bone plate (10), said first channel (16) and said recess (39) coincide and align.

12. Modular osteosynthesis implant assembly (1 ) according to claim 1 to 10, characterized in that said elongate bone plate (10) comprises at least one through bore (18) and/or elongated hole (19), configured to receive at least one secondary bone anchor (80), such as a bone screw, dowel, bolt, pin, locking-screw or cerclage wire.

13. Modular osteosynthesis implant assembly (1 ) according to one of the claim 1 to 12, characterized in that it further comprises primary bone anchors (60) glideably received in said protrusions (34,35).

14. Modular osteosynthesis implant assembly (1 ) according to claim 13, characterized in that said primary bone anchor (60) is an externally threaded screw with a smooth shaft portion with a diameter Ό1 ', a tip portion and a head portion, wherein said thread partially extends from said tip to said head portion, furthermore comprises a circumferential rim of third diameter 3' on said smooth shaft portion, wherein said rim forms a seat to limit the telescoping distance of said primary bone anchor (60).

15. Modular osteosynthesis implant assembly (1 ) according to one of the claims 1 to 14, characterized in that said hollow protrusion of said plate insert has an inner second diameter 'D2' extending through said plate insert, wherein said diameter 'D2^! > 'D1 ' > 'D3' and upon loading of said tip portion of said primary bone anchor (60), said rim hangs over the hollow protrusion end.

16. Modular osteosynthesis implant assembly (1 ) according to one of the claims 1 to 15, characterized in that the first end of said elongate bone plate (10) comprises an attachment feature (14) for assembly of said bone plate (10) to a targeting device to facilitate the placement of said elongate bone plate onto said target bone and guide the insertion of said plate insert, and/or primary bone anchor and/or secondary bone anchor and/or said eventual locking elements.

17. Modular osteosynthesis implant assembly (1 ) according to one of the claims 1 to 16, characterized in that it further comprises a buttress element, preferably in the form of a trochanter fixation plate (90) attachable to said first end for fixation and stabilization of additional fracture fragments.

18. Modular osteosynthesis implant assembly (1 ) according to claim 17, characterized in that the buttress element is not attached to said first end but rather an integral part of said elongate bone plate at said first end.

19. Modular osteosynthesis implant assembly (1 ) according to claim 17 or 18, characterized in that the buttress element comprises at least one arm with at least one screw receiving fixation unit, sized and shaped to be inter-operatively bend to seat flush against the target bone.

20. Modular osteosynthesis implant assembly (1 ) according to one of the claims 1 to 19 for the treatment of proximal femur fractures in open surgery or minimal invasive surgery.

21. Modular osteosynthesis implant assembly (1 ) according to one of the claims 17 to 19, for the treatment of split-off trochanter bone fragments.

22. Modular osteosynthesis implant assembly (1 ) according to one of the claim 1 to 21 , characterized in that said two tubular protrusions (34, 35) are spaced from one another at a distance 'K' smaller than 5 mm.

23. Method for open or minimally invasive stabilization to promote an osteosynthesis, by use of the modular osteosynthesis implant assembly of any of claims 1 to 22, essentially comprising the following surgical steps,

- Reduction of the fracture

- performing a small incision near the epiphysis of the target bone

- preliminary fixation of the fragments with K wires

- Insertion of the elongate bone plate with attached aiming device

- Initial fixation of the elongate bone plate against the target bone

- Pre drilling for the placement of the primary bone anchors

- Insertion of the plate insert

- Fixation of the plate insert with said locking elements

- Insertion of the primary bone anchors

- Insertion of the remaining secondary bone anchors

- Removal of all instruments

24. A kit for assembling the modular osteosynthesis implant assembly of any of claims 1 to 22, wherein said kit comprises elongate bone plates (10) of different lengths comprising different numbers of through bores and elongated holes, furthermore comprising plate inserts (30) having different anatomical angles a, furthermore said kit comprising different primary bone anchors (60) and secondary bone anchors (80) of different lengths and potentially locking elements (50) of different lengths.