IL302305B1

IL302305B1 - Bone fixation implant arrangement

Info

Publication number: IL302305B1
Application number: IL302305A
Authority: IL
Original assignee: Fibioseq Medical Ltd
Priority date: 2023-04-20
Filing date: 2023-04-20
Publication date: 2024-02-01
Also published as: IL302305A

Description

302305/ 02940817127- BONE FIXATION IMPLANT ARRANGEMENT TECHNOLOGICAL FIELD The presently disclosed subject matter generally relates to surgical implants. More particularly, the presently disclosed subject matter relates to a bone fixation implant arrangement for supporting arthroplasty.

BACKGROUND Over the past few decades, minimally invasive surgery has become increasingly common across all medical specialties, including orthopedics. New research and technologies have led to improved methods of many orthopedic surgical procedures such as arthroscopic repairs of sports injuries and microscopic treatment of complex musculoskeletal conditions, and total joint replacement. Minimally invasive surgery is generally performed through tiny incisions instead of a large opening. The smaller incisions allow the patient to have a quicker recovery time and less pain than a traditional open surgery with the same benefits as traditional surgery. In orthopedics, this can mean the difference between exposing the entire joint through a large, open incision and using small, targeted incisions to address only the problem area. This results in less risk during surgery, less post-operative pain, and shorter recovery times. Wrist arthroscopy is often a good alternative to traditional surgery for wrist injuries and other painful wrist conditions, and is widely used for addressing radiocarpal fractures.

The human wrist is a complex joint interface that bridges proximal aspects of the metacarpal bones with distal aspects of radius and ulna. The carpal bones are bones of the wrist that connect these distal aspects of the radial and ulnar bones of the forearm to the bases of the 302305/ 02940817127- eight metacarpal bones of the hand providing multiple joints that intercommunicate in a common synovial cavity. These articulations work together to allow for a wide range of motion in the wrist joint. Most of the wrist motion occurs in the radiocarpal joint (RCJ) and the distal radioulnar joint (DRUJ). The motion of the radiocarpal joint occurs between the radius and the first proximal row of carpal bones, which act together through the articular surface, and between the proximal and distal row of carpal bones.

There is more a limited motion between the distal carpal bones and metacarpal bones in the hand. The DRUJ is a pivot joint located between the distal radius sigmoid notch and ulnar head for supination and pronation movements of the hand. Different wrist pathologies may occur in the wrist bones or joints resulting from conditions such as osteoarthritis, or from traumas, such as bone fractures, for example. A patient, or subject, with these wrist pathologies may experience severe pain during wrist movements ranging to severe disabilities due to limitations in wrist movements.

The wrist joint allows multi-axial movement with wide range of motion in all axes. In a healthy joint, the range of motion (ROM) for flexion-extension (bending of the hand in the direction of the palm or back of the hand) is almost 90 degrees in each direction, and between ° and 30° for ulnar and radial lateral bending of the hand (e.g., in the direction of the thumb or little finger). The center of rotation (COR) in the physiological joint is not fixed. This floating quality of the center of rotation of the joint allows the joint to adjust to and remain stable in the face of large loads.

Commercially available artificial joints are typically designed to rotate around a fixed geometry of concave and convex surfaces, e.g., in the form of ball-and-socket joints. One reason for this is the engineering challenge of providing a wide range of motion under significant loads 302305/ 02940817127- while minimizing wear of the artificial joint. The presently disclosed subject matter addresses bone fracture tendencies in the dorsal ridge of the distal radius that are believed to stem from surgical modifications to dorsal bony structures to accommodate state of the art radiocarpal arthroplasty techniques. The bone fixation implant arrangement according to the present disclosed subject matter removes the requirement to slot, cut or modify these dorsal bony structures for maximizing the integrity of these bony areas thereby reducing fracture potential, and further reducing irritation of overlying or superficial anatomy the distal forearm.

GENERAL DESCRIPTION A bone fixation implant arrangement affixes to a bone having a bone end surface and a bone side surface oriented in an angle with respect to each other. The bone fixation implant arrangement includes an anchor seat, an anchor plate arrangement, including a basal anchor plate and a capping structure, and a series of bridging elements. The anchor seat has an inner seat surface configured for abutting the bone end surface. The basal anchor plate is connectable to the anchor seat so as to facilitate affixation of the implant arrangement to the bone. The basal anchor plate has an inner plate surface configured for abutting the bone side surface. The capping structure is mountable on the basal anchor plate. The bridging elements are configured interconnect the anchor plate arrangement and the anchor seat such that the capping structure anchors ends of the bridging elements.

There is thus provided, in accordance with an embodiment of the presently disclosed subject matter a bone fixation implant arrangement for affixing to a bone having a bone end surface and a bone side surface oriented in an angle with respect to each other. The bone fixation implant arrangement comprises an anchor seat and a basal anchor plate. The anchor seat 302305/ 02940817127- has an inner seat surface configured for abutting the bone end surface. The basal anchor plate is connectable to the anchor seat so as to facilitate the affixation thereof. The basal anchor plate further has an inner plate surface configured for abutting the bone side surface. The basal anchor plate is displaceable relative to the anchor seat, at least prior to being connected thereto.

In some embodiments a select bone side surface is surgically selected to maximize anchored attachment of the basal anchor plate thereto. In some embodiments the bone fixation implant arrangement comprises at least one bridging element configured to facilitate the connecting between the anchor seat and the basal anchor plate. In some embodiments, the at least one bridging element is configured for fixing the anchor seat and the basal anchor plate to each other in spaced relation to each other. In some embodiments, the at least one bridging element has a smooth external surface configured to enable sliding of the at least one bridging element into a preformed channel in the bone when providing the connection between the basal anchor plate and the anchor seat.

In some embodiments, the at least one bridging element of the bone fixation implant arrangement has a main longitudinal bridge axis. The main longitudinal bridge axis extends through each of the basal anchor plate and the anchor seat when the two are connected thereby.

In some embodiments, the main longitudinal bridge axis extends obliquely with respect to each of the inner plate surface and the inner seat surface when the basal anchor plate and the anchor seat are connected by the at least one bridging element. In some embodiments, the at least one bridging element comprises an anchor plate end surface. The anchor plate end surface is obliquely angled relative to the main longitudinal axis of the at least one bridging element, in an angle corresponding to the angle in which the inner plate surface is configured to be positioned 302305/ 02940817127- relative to the main longitudinal axis, when the basal anchor plate and the anchor seat are connected by the at least one bridging element.

In some embodiments, an anchor plate end of the at least one bridging element comprises at least one of a bridge stepped portion and a bridge slot. Correspondingly, the basal anchor plate comprises at least one of a plate stepped portion and a plate slot in some embodiments.

The bridge stepped portion is matable with the plate slot, and the bridge slot is matable with the plate stepped portion. In some embodiments, the bridging element comprises both the bridge stepped portion and the bridge slot. In these embodiments, the basal anchor plate comprises one of the plate stepped portion and the plate slot while the capping anchor plate comprises the other.

In some embodiments, the basal anchor plate constitutes a part of an anchor plate arrangement further comprising a capping anchor plate connectable over the basal anchor plate for anchoring the at least one bridging element thereto.

In some embodiments, the capping anchor plate comprises an outer plate surface having a contour corresponding to that of an inner plate surface of the basal anchor plate. In some embodiments, the capping anchor plate is connected over the at least a portion of the basal anchor plate such that the capping anchor plate is configured to be flush with a remaining portion of the basal anchor plate. In some embodiments, the anchor plate end surface is configured to be flush with at least one of said outside plate surface of the capping anchor plate or an outside plate surface of the basal anchor plate. In some embodiments, the anchor plate arrangement further comprises at least one locking fastener for fastening the capping anchor plate to the basal anchor plate. In some embodiments, the at least one locking fastener is configured for fastening both the basal anchor plate and the capping anchor plate to the bone and to each other. 302305/ 02940817127- In some embodiments, the capping anchor plate comprises a locator protuberance at a deep surface thereof. The locator protuberance mates with a locator aperture formed in the basal anchor plate. In some embodiments, the bridging element(s) are integrally formed with the anchor seat and in some embodiments, the bridging element(s) are detachably attachable to said anchor seat. In some embodiments, a plurality of bridging elements is connectable to at least the basal anchor plate in spaced relation relative to one another. In some embodiments, the plurality of bridging elements is at least three having anchor plate ends arranged in a triangular stance. In some embodiments, the at least one bridging element is an elongated tie rod.

In some embodiments, the basal anchor plate is configured to be anchored to a cortical bone at the bone side surface and the anchor seat is configured to be anchored to an articulating surface of the bone end thereby providing a bi-cortical connection. In some embodiments, the anchor seat of the bone fixation implant arrangement is configured to generally provide an arthroplasty basis. In some embodiments, the bone is a radius bone, and the anchor seat provides a radiocarpal an arthroplasty basis. In some embodiments, the bone side surface is rounded in transverse cross-section. In these embodiments, the inner plate surface is concave and the outer plate surface is convex thereby mimicking the rounded bone side surface. In some embodiments, the bone side surface is deep to at least one of superficial tendon and musculature anatomy. The basal anchor plate is positionable intermediate the select bone side surface and this superficial anatomy.

In some embodiments, the bone is a long bone having a main longitudinal bone axis, and the bone end surface is an articulating surface. The bone side surface is axially spaced relative to the articulating surface along the main longitudinal bone axis. In some embodiments, the bone end is distally located, and the at least one bridging element extends so as to proximally position 302305/ 02940817127- the basal anchor plate at a dorsal bone side surface. In some embodiments, the bone end surface and the bone side surface are angled relative to one another in an angle of least 45 degrees. In some embodiments, the bone end surface and the bone side surface are angled relative to one another in an angle of least 60 degrees to 90 degrees.

There is further provided in accordance with another embodiment of the presently disclosed subject matter a bone fixation implant arrangement for selective affixation to a bone having a bone side surface. The bone fixation implant arrangement comprises an anchor plate arrangement including a basal anchor plate, a capping structure, and at least one bridging element. The basal anchor plate has an inner plate surface configured to abut the bone side surface, and comprises at least one aperture. The capping structure is mountable on the basal anchor plate and comprises at least one cavity in a location corresponding to the at least one aperture in the basal anchor plate when the capping structure is mounted thereto. The at least one bridging element is configured to be received in the at least one aperture and anchored thereat upon mounting of the capping structure onto the basal anchor plate.

In some embodiments, a select bone side surface is surgically selected to maximize anchored attachment of the basal anchor plate thereto. In some embodiments, the basal anchor plate is configured to receive and position an end of the at least one bridging element, and the capping structure is configured to anchor the end when the capping structure is mounted to the basal anchor plate. In some embodiments, the capping structure is a capping anchor plate configured to cover at least a portion of the basal anchor plate when mounted thereto. In some embodiments, the at least one bridging element has a main longitudinal bridge axis configured to extend obliquely with respect to the inner plate surface when anchored to the anchor plate arrangement. 302305/ 02940817127- In some embodiments, the at least one bridging element has a smooth external surface configured to enable sliding of the at least one bridging element into a preformed channel in the bone. In some embodiments, the at least one bridging element has a main longitudinal bridge axis that extends through each of the basal anchor plate and the anchor seat when the two are connected thereby. In some embodiments, the at least one bridging element comprises an anchor plate end surface. The anchor plate end surface is obliquely angled relative to the main longitudinal bridge axis in an angle corresponding to the angle in which the inner plate surface is configured to be positioned relative to main longitudinal bridge axis when the bridging element is anchored to the anchor plate arrangement.

In some embodiments, an anchor plate end of the at least one bridging element comprises at least one of a bridge stepped portion and a bridge slot. Correspondingly, the basal anchor plate comprises at least one of a plate stepped portion and a plate slot. The bridge stepped portion is matable with the plate slot, and the bridge slot is matable with the plate stepped portion. In some embodiments, the bridging element comprises both the bridge stepped portion and the bridge slot. The basal anchor plate comprises one of the plate stepped portion and the plate slot while the capping structure comprises the other. In some embodiments, the capping structure is a capping plate having an outer plate surface having a contour corresponding to that of the inner plate surface of the basal anchor plate.

In some embodiments, the capping anchor plate is connected over the at least a portion of the basal anchor plate such that the capping anchor plate is configured to be flush with a remaining portion of the basal anchor plate. In some embodiments, the anchor plate end surface of the at least one bridging element is configured to be flush with at least one of the outside plate surface of the capping structure or an outside plate surface of the basal anchor plate. In some 302305/ 02940817127- embodiments, the capping anchor plate comprises a locator protuberance at a deep surface thereof, which locator protuberance mates with a locator aperture formed in the basal anchor plate.

In some embodiments, the basal anchor plate is configured to be anchored to a cortical bone at the select bone side surface and the anchor seat is configured to be anchored to an articulating surface of the bone thereby providing a bi-cortical connection. In some embodiments, the at least one bridging element is configured to extend through at least a portion of cancellous bone and at least a portion of cortical bone. In some embodiments, the anchor plate arrangement further comprises at least one locking fastener for fastening the capping structure to the basal anchor plate. In some embodiments, the at least one locking fastener is configured for fastening both the basal anchor plate and the capping structure to the bone and to each other.

In some embodiments, the capping structure comprises a locator protuberance at a deep surface thereof, which locator protuberance mates with a locator aperture formed in the basal anchor plate. In some embodiments, the bone side surface is rounded in transverse cross-section.

In these embodiments, the inner plate surface is concave and an opposite outer plate surface thereof is convex thereby mimicking the rounded bone side surface. In some embodiments, the bone side surface is deep to at least one of superficial tendon and musculature anatomy. The basal anchor plate is positionable intermediate the bone side surface and this superficial anatomy.

In some embodiments, the bone is a long bone having a main longitudinal bone axis, and the bone end surface is an articulating surface. In these embodiments, the bone side surface is axially spaced relative to the articulating surface along the main longitudinal bone axis. In some embodiments, the bone end is distally located, and the at least bridging element extends so as to 302305/ 02940817127- proximally position the basal anchor plate at a dorsal bone side surface. In some embodiments, the anchor seat of the bone fixation implant arrangement is configured to generally provide an arthroplasty basis. In some embodiments, the bone is a radius bone, and the anchor seat provides a radiocarpal hemiarthroplasty basis.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and objectives of the presently disclosed subject matter will become more evident from a consideration of the following brief descriptions of patent drawings.

FIG. 1A is a first sequential simplified diagrammatic depiction of a long bone before a bone fixation implant arrangement according to the presently disclosed subject matter is affixed thereto.

FIG. 1B is a second sequential simplified diagrammatic depiction of the long bone after an anchor seat and a basal anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter are affixed to a select long bone end.

FIG. 1C is a third sequential simplified diagrammatic depiction of the long bone after a tie rod of the bone fixation implant arrangement according to the presently disclosed subject matter interconnects the anchor seat and the basal anchor plate at the select long bone end.

FIG. 1D is a fourth sequential simplified diagrammatic depiction of the long bone after a capping anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter is affixed to the basal anchor plate thereby anchoring an anchor plate end of the tie rod at the select long bone end. 302305/ 02940817127- FIG. 1E is an enlarged fragmentary sectional view of the bone fixation implant arrangement as enlarged and sectioned from FIG. 1D to depict in greater clarity the bone fixation implant arrangement affixed to the select long bone end.

FIG. 2A is a first sequential lateral view of a basal anchor plate and an anchor seat of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 2B is a second sequential lateral view of the basal anchor plate interconnected with the anchor seat by way of a first tie rod of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 2C is a third sequential lateral view of the basal anchor plate interconnected with the anchor seat by way of a plurality of tie rods of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 2D is a fourth sequential view of the basal anchor plate interconnected with the anchor seat by way of the plurality of tie rods and a capping anchor plate anchoring anchor plate ends of the plurality of tie rods of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 3 is an enlarged lateral view of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 4 is an enlarged dorsal plan view of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 5 is an enlarged ventral plan view of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 6 is a dorsal plan view of the basal anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter. 302305/ 02940817127- FIG. 7 is a lateral elevational view of the basal anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 8 is a ventral plan view of the basal anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 9 is an enlarged distal end view of the basal anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 10 is an enlarged proximal end view of the basal anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 11A is a first sequential dorsal plan view of a first tie rod being received and positioned by the basal anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 11B is a second sequential dorsal plan view of first and second tie rods being received and positioned by the basal anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 11C is a third sequential dorsal plan view of first, second and third tie rods being received and positioned by the basal anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 12A is a dorsal plan view of first, second, and third tie rods of the bone fixation implant arrangement spatially positioned relative to one with the basal anchor plate removed for ease of understanding.

FIG. 12B is a lateral view of first, second, and third tie rods of the bone fixation implant arrangement spatially positioned relative to one with the basal anchor plate removed for ease of understanding. 302305/ 02940817127- FIG. 12C is a ventral perspective view of first, second, and third tie rods of the bone fixation implant arrangement spatially positioned relative to one with the basal anchor plate removed for ease of understanding.

FIG. 13 is a dorsal plan view of the capping anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 14 is a lateral elevational view of the capping anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 15 is a ventral plan view of the capping anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 16 is a distal end view of the capping anchor plate of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 17 is a lateral elevational view of the anchor seat of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 18 is an enlarged proximal end view of the anchor seat of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 19 is an enlarged distal end view of the anchor seat of the bone fixation implant arrangement according to the presently disclosed subject matter.

FIG. 20 is a lateral elevational view of the bone fixation implant arrangement providing a an arthroplasty for a radiocarpal joint replacement assembly according to the presently disclosed subject matter.

FIG. 21 is an enlarged perspective view of the bone fixation implant arrangement for a radiocarpal joint replacement assembly according to the presently disclosed subject matter. 302305/ 02940817127- FIG. 22 is an enlarged exploded perspective view of the bone fixation implant arrangement for the radiocarpal joint replacement assembly according to the presently disclosed subject matter.

FIG. 23 is a lateral elevational view of the bone fixation implant arrangement for the radiocarpal joint replacement assembly according to the presently disclosed subject matter shown surgically installed at a distal forearm with surrounding tendon and musculature anatomy.

FIG. 24 is a lateral elevational view of the bone fixation implant arrangement for the radiocarpal joint replacement assembly according to the presently disclosed subject matter shown surgically installed at a distal radius end with a force diagram depicting a compressive force directed into the radiocarpal joint replacement assembly.

FIG. 25 is an enlarged exploded view of a radiocarpal joint showing positioned placement of the anchor seat and plurality of tie rods prior to surgical installation at a distal radius end.

FIG. 26 is an enlarged dorsal perspective view of the basal anchor plate, anchor seat and plurality of tie rods surgically installed at a distal radius end.

FIG. 27 is an enlarged dorsal perspective view of the basal anchor plate, anchor seat and plurality of tie rods surgically installed at the distal radius end with an exploded capping anchor plate being directed into seated engagement in dorsal adjacency to the basal anchor plate.

FIG. 28 is a first enlarged dorsal perspective view of the bone fixation implant arrangement according to the presently disclosed subject matter surgically installed at a distal radius end. 302305/ 02940817127- FIG. 29 is an enlarged dorsal perspective view of an anchor plate arrangement fastener fastening the capping anchor plate to the basal anchor plate as surgically installed upon a dorsal radius side surface.

FIG. 30 is a second enlarged dorsal perspective view of the bone fixation implant arrangement according to the presently disclosed subject showing the anchor plate arrangement fastener and an orthopedic fastener fastening the basal anchor plate to a dorsal radius side surface.

FIG. 31 is a schematic representation of the bone fixation implant arrangement according to the presently disclosed subject surgically installed a distal radius end juxtaposed adjacent superficial anatomy to show positions of the bone fixation implant arrangement and portions of the radiocarpal joint replacement assembly relative to the superficial anatomy.

FIG. 32 is an enlarged dorsal perspective view of the bone fixation implant arrangement according to the presently disclosed subject matter .

FIG. 33 is an enlarged lateral view of the bone fixation implant arrangement according to the presently disclosed subject matter.

DETAILED DESCRIPTION OF THE EMBODIMENTS The radius is one of two forearm bones and is located on the thumb side. The part of the radius connected to the wrist joint is called the distal radius. When the radius breaks near the wrist, it is called a distal radius fracture. Literature related to distal radius fractures inform readers that these fractures typically occur when a person fall on an outstretched or flexed hand and compressive force is directed into the radiocarpal joint. Radiocarpal joint replacement is sometimes required to help the injured person regain use of his or her wrist. State-of-the-art 302305/ 02940817127- techniques sometimes require modification of the cortical bone at the distal radius to support radiocarpal hemiarthroplasty or joint replacement. It has been noted, however, that surgical modifications to the distal radius to support these joint replacements can often lead to re- fracturing of the distal radius.

The prior art thus perceives a need for improvement to bone fixation implant techniques whereby implant arrangements are anchored to intact bone segments adjacent weakened or fractured bone segments to avoid anchoring implants to weakened or fractured bone segments.

In this regard, the presently disclosed subject matter further contemplates applications in those patients presenting degenerative bone conditions as exemplified by osteoarthritis and the like.

For illustrative purposes, the presently disclosed subject matter highlights arrangements and techniques associated with the distal radius as an exemplary application and is not meant to limiting.

While the following specifications generally describe a bi-cortical bone fixation implant arrangement 10 particularly designed for affixation to the distal radius, the bone fixation implant arrangement according to the presently disclosed subject matter may affix to any two surfaces of a select bone whereby the two surfaces are non-parallel to one another. Referencing FIG. 1, the reader will there consider a diagrammatic depiction of a long bone 100 having a select bone side surface at 104 and a bone end surface 119 at a distal bone end 105. The select bone surface 1 has a normal vector as at 120 and the bone end surface 119 has a normal vector as at 121. The normal vectors 120 and 121 are oriented at a non-parallel angle relative to one another, and in this diagrammatic representation the non-parallel angle is on the order of a maximum 90 degrees.

In some embodiments according to the present invention, the select bone side surface 104 and 302305/ 02940817127- the bone end surface 119 may be oriented at least 45 degrees to one another, or at least degrees to one another up to 90 degrees in most cases.

In some embodiments, the bi-cortical bone fixation implant arrangement 10 according to the presently disclosed subject matter may affix to long bones as exemplified by the radius.

Very basically, the long bones are those that are longer than they are wide. The long bone category includes the femora, tibiae, and fibulae of the legs, and the humeri, radii, and ulnae of the arms. The outer shell or cortex of a long bone is compact or cortical bone and the deeper layer of a long bone at the epiphysis and metaphysis portions is generally cancellous or spongy bone which contains bone marrow in the medullary cavity. FIG. 1A further depicts and references an outer layer of cortical bone 101 and a deeper layer of cancellous bone 102 at the distal bone end 105. While the bone fixation implant arrangement 10 according to the presently disclosed subject matter has been designed to support arthroplasty involving long bones, and particularly radiocarpal arthroplasty involving the radius, these specifications are not to be construed as limited to long bone applications.

Comparatively referencing Figs. 1A through 1E, the reader will there consider a diagrammatically depicted long bone 100 having a main longitudinal bone axis 103. The select bone side surface 104 may be surgically selected by a surgeon to maximize anchored attachment of a basal anchor plate 14 of the bone fixation implant arrangement 10 thereto in axially spaced relation relative to the articulating surface 119 of the distal bone end 105. As used in these specifications, the descriptor, the term "fixing" refers to fixing at least most of the degrees of freedom between elements, and particularly all of them. i.e., the anchor may be construed to connote fixing at least most of the degrees of freedom between opposed elements, and not necessarily all degrees of freedom. The proximal bone end is referenced at 106 and the dorsal 302305/ 02940817127- and ventral bone side surfaces are referenced at 107 and 108, respectively. These series of diagrammatic representations are presented to provide a simplified understanding of implant arrangement placement relative to an exemplary long bone 100 and are not mean to be limiting.

Recalling the prior art perceives a need for bone fixation implantation arrangements that preserve so far as practicable the structural integrity of the outer cortex for preventing fractures generally and to prevent fractures in the dorsal ridge of the distal radius particularly, the bone fixation implant arrangement 10 according to the presently disclosed subject matter is configured to affix to a long bone 100 having a main longitudinal bone axis 103 extending through the bone and passing through opposed bone ends as exemplified by distal and proximal bone ends 105 and 106.

In some embodiments, the bi-cortical bone fixation implant arrangement 10 according to the presently disclosed subject matter comprises an anchor seat 11 attachable to a distal bone end 105 and an anchor plate arrangement 12 attachable to the select bone side surface 104 such that the normal vector 122 of the anchor plate arrangement 12 and the normal vector 123 of the anchor seat 11 are oriented in a non-parallel angle relative to one another to coincide with the angular arrangements of the select bone side surface 104 and the bone end surface 119. In some embodiments, the bone fixation implant arrangement 10 comprises the anchor seat 11 and at least a basal anchor plate 14 of the anchor plate arrangement 12. The anchor plate arrangement 12 comprises at least the basal anchor plate 14 and an outer capping structure that mounts to and covers at least a portion of the basal anchor plate 14. In some embodiments, the outer capping structure is a capping anchor plate as at 20. When affixed to a bone 100, the anchor seat 11 and select anchor plate arrangement(s) are spatially and structurally configured to be non-parallel to one another as prefaced above. 302305/ 02940817127- In this regard, the reader will note the anchor seat 11 has an inner seat surface configured for abutting the articulating surface 119 of the bone end 105 in some embodiments.

The basal anchor plate has an inner plate surface 15 configured to abut the select bone side surface 104. The basal anchor plate 14 is connectable to the anchor seat 11 via one or more bridging elements 16 so as to facilitate affixation of the bone fixation implant arrangement 10 to the bone 100. In long bone applications, the outer cortex is generally rounded in transverse cross-section. Accordingly, in some embodiments, the inner plate surface 15 the basal anchor plate 14 is generally concave in transverse cross-section particularly configured for abutting the bone side surface 104. If flat bone applications, the basal anchor plate 14 may have a flat inner plate surface that corresponds to a flat bone side surface.

In some embodiments, the basal anchor plate 14 and the anchor seat 11 may be movably positioned or displaceably positioned relative to one another at least prior to be connected to one another for enabling a surgeon to select optimum attachment points at the bone side surface 1 and the bone end 105. Similarly, the basal anchor plate 14 and the capping structure are configured to have correspondingly matable shapes further enabling movement of one element with respect to the other along or about a particular axis prior to final affixation or anchored attachment to one another. In some embodiments, the capping structure or capping anchor plate may be anchored to the basal anchor plate 14 and the anchor plate arrangement 12 may be anchored to the select bone side surface 104 via at least one anchoring fastener exemplified by any suitable orthopedic fastener as selected by the surgical team. Similarly, the anchor seat may be anchored to an articulating surface 119 at the bone end 105 of the bone 100 thereby providing a bi-cortical connection via one or more bridging elements 21. 302305/ 02940817127- The bi-cortical connection is bolstered by at least one primary bridging element exemplified by an elongate tie rod type structure in certain some embodiments. In some embodiments, the at least one primary bridging element 16 extends medially relative to the basal anchor plate 14 for interconnecting the anchor seat 11 and the basal anchor plate 14 via at least one oblique road or channel 109 formed in the bone 100 from the bone side surface 104 to the articulating surface 119 at the bone end 105 as diagrammatically and comparatively depicted in FIGS. 1C and 1E, and as more particularly depicted in FIG. 2B through FIG. 5. The oblique roads or channels 109 are pre-formed in the bone 100 once select placement(s) of the basal anchor plate 14 and anchor seat 11 are determined by the surgical team.

The outer or external surface of the bridging element(s) 16 are smooth for easing insertion of the bridging elements 16 into the bone 100 via the pre-formed channels 109. In some embodiments, one or more secondary bridging elements 16 bolster the seat-to-plate interconnection. In this regard, the reader may reference FIGS. 11A through 11C showing sequential additions of bridging elements 16 to the basal anchor plate 14. In some embodiments, the secondary bridging elements 16 extend laterally relative to the medially extending primary bridging element 16 for bolstering the interconnection between the anchor seat 11 and the basal anchor plate 14 via additional pre-formed channels 109 as further depicted and referenced in FIG. 25.

Each bridging element 16 or elongate tie rod is configured to extend obliquely relative to each of the basal anchor plate 14 and the anchor seat 11 when the two are connected thereby fixing the basal anchor plate 14 in axially spaced relation relative to the anchor seat 11 at the select bone side surface 104 along the main longitudinal bone axis 103. At least one bridging element 16 has a main longitudinal bridge axis as at 110, which main longitudinal bridge axis 302305/ 02940817127- 110 extends through each of the basal anchor plate 14 and the anchor seat 11 when the two are connected thereby. The main longitudinal bridge axis 110 extends obliquely with respect to each of the inner plate surface 15 and the inner seat surface 13 when the basal anchor plate 14 and the anchor seat 11 are connected by the at least one bridging element 16. In some embodiments, each bridging element 16 or elongate tie rod extends through at least a portion of cancellous bone 102 and at least a portion of cortical bone 101 through which the preformed oblique roads or channels 109 extend thereby reducing dependency of implant stability on the vitality and rejuvenation of the cancellous bone 102.

The bone end 105 to which the anchor seat 11 may be affixed is distally located in certain embodiments. The bridging elements 16 facilitate the interconnection between the basal anchor plat 14 and the anchor seat 11 and extend obliquely through the distal bone end 105 to the select bone side surface 104 to proximally position the basal anchor plate 14 at the select bone side surface 104 dorsally in some embodiments. The select bone side surface 104 is surgically selected to be deep to at least one of superficial radiocarpal tendon(s) 55 and musculature 56.

The anchor plate arrangement 12 is positioned intermediate the select bone side surface 104 and portions of this overlying superficial anatomy in some embodiments for mimicking the cortical bone surface in a low-profile manner so as to reduce irritation to the overlying anatomy.

In some applications, the select bone side surface 104 is rounded in transverse cross- section and the basal anchor plate 14 comprises a generally convex inner plate surface and a convex outer plate surface as at 18 for mimicking the rounded cortical bone surface at the select bone side surface 104. Similarly, the capping structure or capping anchor plate 20 comprises a generally concave inner plate surface as at 49 and a generally convex outer plate surface as at 19.

In flat bone applications, the inner plate surface 15 of the basal anchor plate 14 and the inner 302305/ 02940817127- plate surface 49 of the capping anchor plate 20 are generally flat to correspond with the underlying bone surface for minimizing the profile and reducing irritation to overlying anatomy.

The outer plate surface 19 of the anchor plate arrangement 12 is preferably smooth for minimally engaging overlying tissue and tendons in some embodiments. Anchor plate ends of the bridging elements 16 comprise ovular anchor plate end surfaces 17 that may be embedded in the upper or outer capping anchor plate 20 that are level or flush with the smooth outer plate surface 19. In some embodiments, the anchor plate ends 21 may be covered by end-capping cavities formed at the inner plate surface 49 of the capping anchor plate 20 such that the outer plate surface 19 overlies the anchor plate ends 21 preventing direct contact with overlying tissues and tendons.

In radial bone applications, the obliquely extending bridging elements 16 pass beneath the Lister Tubercle and distal radius when the tendons 55 are exposed at distal region 115 as referenced in FIG. 31 and emerge proximally when tendons 55 are protected by a layer of musculature 56 as at proximal region 116 in FIG. 31. This structural arrangement helps preserve structural integrity of dorsal bony structures at the distal radius in these embodiments. In other words, there is no need to slot, cut or otherwise modify the dorsal radial bony structures which may otherwise compromise the structural integrity of the bony structure there located. This decreases the potential for fracture at the bone end 105. Further, the proximal placement of the anchor plate arrangement 12 at region 116 avoids the potential for overlying tendon irritation at distal region 115.

Each bridging element 16 comprises an angle of inclination 111 relative to the main longitudinal bone axis 103 configured to position the basal anchor plate 14 relative to the anchor seat 11 at the select bone side surface 104. It will be recalled the select bone side surface 104 is 302305/ 02940817127- surgically selected to maximize anchored attachment of the basal anchor plate 14 thereto and reduce irritation to anatomy superficially located relative to the bone fixation implant arrangement 10. In some embodiments, each bridging element 16 has a main longitudinal bridge axis 110. The anchor plate ends 21 of the bridging elements have an ovular anchor plate end surface 17 obliquely angled relative to the main longitudinal bridge axis 110. In some embodiments, the ovular anchor plate end surface(s) 17 may be positioned along the basal anchor plate 14 in raised relation to the outer plate surface 18 of the basal anchor plate 14. In some embodiments, the ovular anchor plate end surface(s) 17 may be positioned along the basal anchor plate 14 in flush relation to the outer plate surface 18 of the basal anchor plate 14.

As prefaced above, the basal anchor plate 14 constitutes a part of the anchor plate arrangement 12 consisting of one or more anchor plates or structures. The anchor plate arrangement 12 has a plate arrangement outer surface as at 19 configured to be disposed opposite the inner plate surface 15 when the bone fixation implant arrangement 10 is affixed to the bone 100. The plate arrangement outer surface 19 is shaped correspondingly to the inner plate surface in some embodiments for mimicking the outer cortical surface of the bone 100. In some embodiments, the ovular anchor plate end surface(s) 17 are configured to be flush with the outer surface 19 of the multilayered anchor plate arrangement 12 further configured to be proximally positioned relative to the anchor seat 11 when the bone fixation implant arrangement 10 is affixed to the bone 100.

In some embodiments, the anchor plate arrangement 12 further comprises a capping anchor plate 20 configured to seat down or mount upon at least a portion of the basal anchor plate 14 for anchoring the anchor plate end 21 of each bridging element 16 that has been positioned by the basal anchor plate 14 deep to the capping anchor plate 20. Recalling that the 302305/ 02940817127- ovular anchor plate end surface 17 is raised relative to the outer plate surface 18 of the basal anchor plate 14 in some embodiments, the capping anchor plate 20 anchors the ovular anchor plate end surface 17 such that the ovular anchor plate end surface 17 is flush with the outer plate surface 19 of the capping anchor plate 20. In some embodiments, the ovular anchor plate end surface(s) 17 are capped by the mating capping plate 20. An anchor plate arrangement locking fastener 30 fastens the capping anchor plate 20 to the basal anchor plate 14 via axially aligned fastener-receiving apertures formed in the anchor plate arrangement 12. A countersunk fastener- receiving aperture 32 is formed in the capping anchor plate 20 and a corresponding fastener- receiving aperture 33 is formed in the basal anchor plate 14 in some embodiments.

In some embodiments, at least one ovular end-receiving aperture 31, configured to be relatively larger than the ovular anchor plate end surface 17, is formed in the capping anchor plate 20 which receives the anchor plate end 21 of each bridging element 16. In some embodiments, at least one end-receiving cavity configured to receive and cap the anchor plate end 21, is provided. In some embodiments, the cavity may not extend through the plane of the capping anchor plate 20 and in some embodiments the cavity is essentially an end-receiving aperture. The ovular anchor plate end surface 17 is configured to be flush with the outer plate surface 19 and secured in anchored position by the end-receiving aperture(s) 31 in some embodiments. Together the locking fastener 30, the opposed mating surfaces 18 and 49 of the plates 14 and 20, and the ovular end-receiving aperture(s) 31, configured to anchor the anchor plate end(s) 21, secure the capping anchor plate 20 in a fixed position relative to the basal anchor plate 14. The basal anchor plate 14 and the capping anchor plate 20 essentially provide structure that widens or expands the contact surface area of the anchor plate arrangement 12 with the bone 100 for reducing the risk of implant migration or subsidence. 302305/ 02940817127- As introduced above, the bone fixation implant arrangement 10 according to the presently disclosed subject matter may comprise a plurality of bridging elements 16 each of which comprise a longitudinal bridge axis 110, which axes 110 may be parallel to one another in some embodiments. The anchor plate ends 21 of the plurality of bridging elements 16 are received and positioned by the basal anchor plate 14 in spaced relation relative to one another in certain embodiments. In this regard, the reader is directed to FIGS. 6 – 8 detailing the basal anchor plate 14 in isolation from other components of the bone fixation implant arrangement 10. The basal anchor plate 14 comprises a series of end-receiving formations in certain embodiments. The end-receiving formations may include at least one end-receiving aperture 22 positioned medially relative to laterally opposed plate sides 23 of the basal anchor plate 14 and centrally relative to a first or proximal plate end 24 and a second or distal plate end 25 of the basal anchor plate 14.

The end-receiving formations may further comprise laterally opposed end-receiving depressions 26 at the second or distal plate end 25. The end-receiving formations are configured to receive and position anchor plate ends 21 of the bridging elements 16 such that the end-receiving aperture 22 receives and positions an anchor plate end 21 of the primary bridging element 16 and the end-receiving depressions 26 receive and position anchor plate ends 21 of laterally opposed bridging elements 16.

In some embodiments, the number of bridging elements 16 equal at least three and are extended through the preformed oblique roads or channels 109 formed in the distal bone end 1 to the proximally located select bone side surface 104 for improving resistance to moments and rotation loads, further reducing the risk of implant migration or subsidence. The arrangement of the anchor plate ends 21 provides a triangular stance 112 at the basal anchor plate 14 in these embodiments. In some embodiments, longitudinally opposed anchor seat ends 27 of the bridging 302305/ 02940817127- elements mate with structure at the inner seat surface 13 of the anchor seat 11 also providing a triangular stance 113 at the anchor seat 11 as generally depicted and referenced in FIG. 22.

In some embodiments, the anchor seat ends 27 of the bridging elements 16 comprise male structure 28 matable with female structure 29 formed at the inner seat surface 13 extending obliquely and proximally therefrom. In some embodiments, the anchor seat ends 27 may each comprise female structure and the inner seat surface 13 may comprise corresponding male structure for enabling the anchor seat ends 27 to mate therewith. The bridging elements 16 may be detachably attachable to the anchor seat 11 in some embodiments, and may be integrally formed with the anchor seat 11 in certain embodiments.

The bridging elements 16 according to the presently disclosed subject matter interconnect the anchor seat 11 and the anchor plate arrangement 12 without screws or threaded fasteners thereby reducing the risk for galvanic corrosion in threads of screws for two basic reasons.

Firstly, there is no less friction in the connection points, as well as reduced contact forces between elements made of different materials, that may damage the anodized layer in either Cobalt-Chromium (CoCr) and Titanium (Ti) parts as a preferred material construction of the bridging elements 16. CoCr and Ti materials are known for their high resistance to corrosion by providing an anodized, inert outer layer that prevents galvanic conditions. Further, the contact surface area of the described connection method is relatively streamlined reducing or minimizing interactions with surrounding tissue as compared to more commonplace connection methods including the use of M3 screws and the like.

Whereas threaded fasteners provide a connection method that operates primarily by tightening with relatively increased contact surface area at the thread surfacing, the presently disclosed subject matter provides a geometric interlocking method, and the associated reduction 302305/ 02940817127- in contact forces reduces the risk for galvanic corrosion otherwise inherent when preferred raw materials of the anchoring elements differ. In surgical applications, galvanic corrosion occurs during as bioelectrochemical processes in which one metal corrodes preferentially when it is in communication with another, in the presence of an electrolytic environment. In other words, the bridging elements 16 reduce contact forces between opposed elements of differing raw material construction thereby reducing galvanic corrosion of select elements depending the material construction of the anchoring elements.

The described seat-to-plate interconnection creates a closed and stable structure before connection to cortical bone 101 which allows compression of the anchor plate arrangement with a standard compression type locking fastener 30. Other orthopedic fasteners 34 pass through fastener-receiving apertures 35 formed in both the basal anchor plate 14 and the capping anchor plate 20 for anchoring the bone fixation implant arrangement 10 to the bone 100 in some embodiments. The basal anchor plate 14 prevents movement of the implant arrangement distally, dorsally, and laterally. The capping anchor plate 20 prevents movement of the implant arrangement proximally, distally, ventrally, and laterally. The multilayered anchor plate arrangement 12 provides one unified structure that allows a geometric locking of tertiary bridging elements 16 without threads or welding.

In some embodiments, the anchor plate end(s) 21 of the bridging elements 16 further comprise bridge stepped portions 36 at exterior first sides thereof as generally depicted and referenced in FIGS. 17A and 17B. Further, the anchor plate end(s) 21 of the bridging elements 16 may further comprise bridge slots 37 at exterior second sides opposite the first sides. In some embodiments, the bridge stepped portions 36 are configured to mate with opposed plate stepped portions 38 formed at the inner plate surface 49 of the capping anchor plate 20 in adjacency to 302305/ 02940817127- the end-receiving aperture(s) 31. The bridge slots 37 are configured to mate with slot- engagement portions 39 of the basal anchor plate 14 in some embodiments. In some embodiments, the anchor plate ends 21 of the bridging elements 16 comprises at least one of a bridge stepped portion and a bridge slot. Correspondingly, the basal anchor plate 14 may comprise at least one of a plate stepped portion and a plate slot. The bridge stepped portion is matable with the plate slot, and the bridge slot is matable with the plate stepped portion in these embodiments.

In some embodiments, the bridging elements 16 each comprise both the bridge stepped portion 36 and the bridge slot 37, and the basal anchor plate 14 comprises one of the plate stepped portion and the plate slot while the capping structure or capping anchor plate comprises the other. The bridge stepped portions 36 and the bridge slots 37, in cooperative engagement with plate stepped portions 38 and the slot-engagement portions 39, are configured to provide a geometric lock in all dimensions for preventing implant migration and subsidence.

The inner plate surface 49 of the capping anchor plate 20 may further comprise a locator protuberance 40 in some embodiments. The locator protuberance 40 mates with or abuts a locator abutment portion 41 formed in the basal anchor plate 14 at an end of the end-receiving aperture 22.

Recalling the basal anchor plate 14 may comprise a first or proximal plate end as at and a second or distal plate end as at 25 in some embodiments, the first plate end 24 may further comprise a raised end locator as at 42, which raised end locator 42 comprises a locator abutment portion 47. The raised end locator 42 has a first end thickness 114 greater in magnitude than a second end thickness 117 of the second plate end 25 as generally and comparatively depicted in FIGS. 9 and 10. The first end thickness 114 is the maximum thickness of the anchor plate 302305/ 02940817127- arrangement 12 in some embodiments. The maximum thickness 114 provides a low-profile implant arrangement that mimics the cortical (dorsal) bone surface 104 at region 116.

Noting that the first end thickness 114 is the maximum thickness of the anchor plate arrangement 12, the capping anchor plate 20 comprises a substantially uniform capping plate thickness 118. Together, the capping plate thickness 118 and the second end thickness 117 equal the first end thickness 114. A first or proximal capping plate end 44 of the capping anchor plate abuts the raised end locator 42 at the locator abutment portion 47and a second or distal capping plate end 45 overlies the second or basal plate end 25. The outer plate surface 19 is flush with an outer locator surface 43 of the raised end locator 42 in some embodiments. In other words, when the capping anchor plate 20 is connected over the at least a portion of the basal anchor plate 14, the capping anchor plate 20 is configured to be flush with a remaining portion of the basal anchor plate 14.

In some embodiments, the anchor seat 11 of the bone fixation implant arrangement provides a hemiarthroplasty basis at anchor seat surface 46, which anchor seat surface provides a synthetic articulating surface for articulating with a radiocarpal joint replacement assembly 50 in some embodiments. As previously introduced, the bone fixation implant arrangement 100 according to the presently disclosed subject matter may support partial or full wrist arthroplasty or radiocarpal joint replacement. The anchor seat 11 essentially provides an interface for supporting the joint replacement assembly 50 basically comprising a socket structure 51, a ball structure 52, a set screw 53, and a bracket structure 54. In some embodiments, the anchor seat provides a radiocarpal hemiarthroplasty basis. Referencing FIGS. through 23, the reader will there consider the hemiarthroplasty extension hardware as 302305/ 02940817127- extended from the anchor seat 11. Orthopedic fasteners have been removed from FIG. 22 to ease understanding of the hemiarthroplasty component arrangement.

Referencing FIG. 23, the bone fixation implant arrangement 10 according to the presently disclosed subject matter is a low profile hemiarthroplasty basis that does not extend above the dorsal plane 107 so as to prevent irritation to the extensor tendons 55 and soft tissues in that area.

The distal bone end 105 extends deep to the extensor tendons 55 and proximal low-profile portions of the bone fixation implant arrangement 10 extend deep to the musculature 56. The bone fixation implant arrangement 10 can be surgically installed in operating rooms with limited tools and provides a robust basis that is relatively stronger than the carpal components. The bone fixation implant arrangement 10 provides a relatively easy arrangement to disassemble and revise, if necessary.

The oblique orientation of the bridging elements 16, exemplified by elongate tie rods in some embodiments, assist in countering pullout forces. If Fc is an exemplary compression load directed in the radiocarpal joint, Fcy is the shear load directed toward dorsal pullout and is approximately 50% of Fc. The force vector component Fcx is an axial load that is directed toward implant subsidence. The Fcx load is smaller by 20% in some embodiments. The bone fixation implant arrangement 10 according to the presently disclosed subject matter can be used for hemiarthroplasty and particularly partial joint replacement on the radial side as exemplified by the drawings and descriptions submitted in support of these specifications. Any two suitable materials can be used for the construction of the anchor plate arrangement 12 and the anchor seat 11. Further, the design allows the use of polyethylene, carbon, or other plastics at the articulating anchor seat surface 46 in hemiarthroplasty procedures.

Claims

302305/ 02940817184- What is claimed is:

1. A bone fixation implant arrangement for affixing to a bone having a longitudinal bone axis, a bone end surface and a bone side surface oriented in an angle with respect to each other, said arrangement comprising: an anchor seat having an inner seat surface configured for abutting the bone end surface; a basal anchor plate being connectable to said anchor seat so as to facilitate said affixing, and having an inner plate surface configured for abutting the bone side surface; and at least one bridging element configured to extend obliquely relative to each of the inner plate surface and the inner seat surface, via a channel in the bone to facilitate the connection between the anchor seat and the basal anchor plate, and thereby fix the basal anchor plate in axially spaced relation relative to the anchor seat at the bone side surface along a main longitudinal bridge axis being oblique to said longitudinal bone axis.

2. The bone fixation implant arrangement according to claim 1, wherein the at least one bridging element has a smooth external surface.

3. The bone fixation implant arrangement according to any one of claims 1 and 2, wherein the at least one bridging element has the main longitudinal bridge axis, the main 302305/ 02940817184- longitudinal bridge axis extending through each of the basal anchor plate and the anchor seat when the two are connected thereby.

4. The bone fixation implant arrangement of claim 3, wherein the main longitudinal bridge axis extends obliquely with respect to each of the inner plate surface and the inner seat surface when the basal anchor plate and the anchor seat are connected by the at least one bridging element.

5. The bone fixation implant arrangement of any one of claims 3 and 4, wherein the at least one bridging element comprises an anchor plate end surface, the anchor plate end surface being obliquely angled relative to the main longitudinal axis of the at least one bridging element, in an angle corresponding to the angle in which the inner plate surface is configured to be positioned relative to said main longitudinal axis, when the basal anchor plate and the anchor seat are connected by said at least one bridging element.

6. The bone fixation implant arrangement of claim 5, wherein an anchor plate end of the at least one bridging element comprises at least one of a bridge stepped portion and a bridge slot, and correspondingly, said basal anchor plate comprises at least one of a plate stepped portion and a plate slot, the bridge stepped portion being matable with the plate slot, and the bridge slot being matable with the plate stepped portion. 302305/ 02940817184-

7. The bone fixation implant arrangement of any one of the preceding claims, wherein the basal anchor plate constitutes a part of an anchor plate arrangement further comprising a capping anchor plate connectable over said basal anchor plate for anchoring the at least one bridging element thereto.

8. The bone fixation implant arrangement of claim 7, wherein said bridging element comprises both the bridge stepped portion and the bridge slot, and wherein said basal anchor plate comprises one of the plate stepped portion and the plate slot while the capping anchor plate comprises the other.

9. The bone fixation implant arrangement of claim 7 or claim 8, wherein said capping anchor plate comprises an outer plate surface having a contour corresponding to that of an inner plate surface of the basal anchor plate.

10. The bone fixation implant arrangement of any one of claims 7 to 9, wherein when the capping anchor plate is connected over at least a portion of the basal anchor plate, the capping anchor plate is configured to be flush with a remaining portion of the basal anchor plate.

11. The bone fixation implant arrangement of any one of claims 7 to 10, wherein an anchor plate end surface of the at least one bridging element is configured to be flush with at least one of an outside plate surface of the capping anchor plate or an outside plate surface of the basal anchor plate. 302305/ 02940817184-

12. The bone fixation implant arrangement of any one of claims 7 to 11, wherein said anchor plate arrangement further comprises at least one locking fastener for fastening the capping anchor plate to the basal anchor plate.

13. The bone fixation implant arrangement of claim 12, wherein the at least one locking fastener is configured for fastening both the basal anchor plate and the capping anchor plate to the bone and to each other.

14. The bone fixation implant arrangement of any one of claims 7 to 13, wherein the capping anchor plate comprises a locator protuberance at a deep surface thereof, the locator protuberance mating with a locator aperture formed in the basal anchor plate.

15. The bone fixation arrangement according to any one of the preceding claims, wherein said bridging element is detachably attachable to said anchor seat.

16. The bone fixation implant arrangement according to any one of the preceding claims, comprising a plurality of bridging elements connectable to at least the basal anchor plate in spaced relation relative to one another. 302305/ 02940817184-

17. The bone fixation implant arrangement of any one of the preceding claims, wherein said at least one bridging element is an elongated tie rod.

18. The bone fixation implant arrangement according to any one of the preceding claims, wherein the basal anchor plate is configured to be anchored to a cortical bone at the bone side surface and the anchor seat is configured to be anchored to an articulating surface of the bone end thereby providing a bi-cortical connection.

19. The bone fixation implant arrangement of any one of the preceding claims, wherein the anchor seat is configured to provide a hemiarthroplasty basis.