JP2013005984A - Bone plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bone plate sufficiently reducing friction between the tendon and the surface of the bone plate without lowering the strength of the bone plate.SOLUTION: This bone plate 10 for fixing a site of fracture of the distal radius from a palm side is formed with a low-friction coating layer 15 at a part where the surface 17 of the bone plate 10 and the tendon 95 come into contact with each other. This bone plate 10 is formed with the low-friction coating layer 15 to reduce a friction coefficient of the bone plate surface 17 to the tendon 95. Even if the bone plate 10 has a relatively high strength (relatively bulky), the friction to the tendon 95 can be suppressed.

Description

  The present invention relates to a bone plate used for fixing a fracture of a distal radius, and more particularly to a bone plate for fixing from the palm side.

  In recent years, surgery using a bone plate that is fixed from the palm side to a distal radius fracture has been performed (for example, Non-Patent Documents 1 and 2). This bone plate is placed between the radius and the tendon on the palm side (for example, the long flexor flexor tendon (FPL)) and then fixed to the radius with a bone screw. When the finger is bent, the tendon slides over the surface of the bone plate.

After the bone plate is installed, the tendon that slides on the surface of the bone plate may be inflamed or partially or completely torn. In addition, tendons may adhere to surrounding tissue due to tendon inflammation and tear. If the tendon does not move normally due to inflammation, tearing, or adhesion of the tendon, problems such as inflexible movement of fingers occur.
One cause of such tendon inflammation and rupture is believed to be "friction between the tendon and the bone plate" that occurs each time the tendon slides on the surface of the bone plate.

  Therefore, for the purpose of reducing friction between the tendon and the bone plate, a bone plate (for example, Patent Document 1) thinner than a normal bone plate (for example, Patent Document 1) or a mirror plate with a mirror-finished surface ( For example, claim 1) of Patent Document 2 has been proposed.

Patent Document 1 (particularly claim 20, paragraph [0012]) states that the plate may be bulky and cause irritation and pain of tendons and soft tissues, and in order to avoid them, a low profile is provided. It is disclosed that having a plate is effective.
In Patent Document 2 (particularly, paragraphs [0023] and [0048]), the surface of the bone plate that is in contact with the soft tissue is mirror-finished, thereby improving the adhesiveness and compatibility with the soft tissue after the operation. The effect of improving the tissue healing and the effect of reducing friction against soft tissue are described.

JP 2011-510799 A JP 2005-21420 A

Wakami Azusa, 2 others, “A case of long flexor tendon rupture after fracture of the distal radius fracture rocking plate”, Chubu Taisho Journal, Vol. 51, No. 6, p.1187- 1188 Satoshi Hyoda, 5 others, “A case of partial fracture of the long flexor tendon after fracture of the distal radius”, Chubu Ryoji, Vol. 53, No. 5, pp. 1159-1160

However, the low profile bone plate as in Patent Document 1 has low strength, and there is a high risk that the bone plate breaks in the body. If the bone plate breaks, it is necessary to remove the bone plate by re-operation, which places a burden on the patient.
Moreover, in the bone plate of patent document 2, although the mirror-finished surface is supposed that the friction with respect to a soft tissue is low, it is supposed that the adhesiveness with respect to a soft tissue is high. For this reason, when the surface of the bone plate is mirror-finished, the tendon adheres to the surface of the bone plate, and the friction between the surface of the bone plate and the tendon may not be sufficiently reduced.

  Then, an object of this invention is to provide the bone plate which can fully reduce the friction between a tendon and the surface of a bone plate, without reducing the intensity | strength of a bone plate.

The bone plate of the present invention is a bone plate for fixing the fracture site of the distal radius fracture from the palm side, and a low friction coating layer is formed on a portion where the surface of the bone plate and the tendon are in contact with each other It is characterized by that.
In the present invention, the “low friction coating layer 15” is a layer having a small coefficient of friction against a soft tissue of a living body such as a tendon.

  In the bone plate of the present invention, by forming a low friction coating layer, the friction coefficient of the bone plate surface against the tendon can be lowered, so even with a bone plate that is bulkier than Patent Document 1, friction against the tendon can be suppressed. . Further, since the low friction coating layer has a small coefficient of friction with respect to soft tissue, it can reduce friction with respect to a tendon as compared with a mirror-finished bone plate as in Patent Document 2.

  As described above, the bone plate of the present invention can sufficiently reduce the friction between the tendon and the surface of the bone plate without reducing the strength of the bone plate.

FIG. 1 shows a bone plate for a distal portion of the radius, where (a) is a schematic front view and (b) is a schematic cross-sectional view. FIG. 2 is a schematic front view showing a state in which the bone plate of FIG. 1 is fixed to the fracture portion at the distal end of the radius. FIG. 3 is a schematic side view showing a state in which the bone plate of FIG. 1 is fixed to the fracture portion at the distal end of the radius. FIG. 4 is a schematic front view showing a state in which the bone plate according to Embodiment 1 is fixed to the fracture portion at the distal end of the radius. FIG. 5 is a schematic side view showing a state in which the bone plate according to Embodiment 1 is fixed to the fracture portion at the distal end of the radius. FIG. 6 is a schematic front view showing a state in which the bone plate according to Embodiment 2 is fixed to the fracture portion at the distal end of the radius. FIG. 7 is a schematic side view showing a state in which the bone plate according to Embodiment 2 is fixed to the fracture portion at the distal end of the radius. FIG. 8 is a schematic front view showing a state in which the bone plate according to Embodiment 3 is fixed to the fracture portion at the distal end of the radius. FIG. 9 is a schematic side view showing a state in which the bone plate according to Embodiment 3 is fixed to the fracture portion at the distal end of the radius. FIG. 10 is a perspective view of a bone pin for fixing a bone plate according to the present invention. FIG. 11 is a perspective view of a bone screw for fixing a bone plate according to the present invention. FIG. 12 is a perspective view of another bone screw for fixing the bone plate according to the present invention. FIG. 13 is a schematic view of a low friction coating layer formed on a bone plate according to the present invention. FIG. 14 is a schematic view of another low friction coating layer formed on the bone plate according to the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating specific directions and positions (for example, “up”, “down”, “right”, “left” and other terms including those terms) are used as necessary. . The use of these terms is to facilitate understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Moreover, the part of the same code | symbol which appears in several drawing shows the same part or member.

  The bone plate 10 for fixing the fracture portion of the distal radius fracture from the palm side is composed of a substantially T-shaped plate-like body extending long in the distal-proximal direction (DP direction) (FIG. 1). To FIG. 2). As shown in FIGS. 1 (a) and 2, the proximal end portion 10P is an elongated strip, and the distal end portion 10D has a shape extending substantially laterally with respect to the proximal end portion 10P (FIG. 1). (A)). Accordingly, the proximal end portion 10P can be disposed along the diaphysis 90P of the radius 90, and the distal end portion 10D conforms to the bulging shape of the epiphysis 90D of the radius 90 (FIG. 2). Further, the proximal end portion 10P is inclined toward the surface 17 side with respect to the distal end portion 10D (FIG. 1B). As a result, the bone plate 10 conforms to the shape of the surface of the distal portion of the radius (the end portion 90D protrudes and the space between the end portion 90D and the diaphysis 90P is depressed) (FIG. 3).

  As shown in FIGS. 2 and 3, the bone plate 10 is disposed between the rib 90 and a tendon 95 (for example, the long flexor tendon (FPL)). When the proximal end portion 10 </ b> P of the bone plate 10 is long, the bone plate 10 extends between the rib 90 and a muscle (for example, a long thumb flexor) 94 connected to the tendon 95. The bone plate 10 arranged at a predetermined position is fixed to the rib 90 by a bone pin 80 and a bone screw 70. When a finger (for example, thumb) is bent in this state, the muscle 94 contracts and pulls the tendon 95, and the tendon 95 moves along the direction of arrow A. At this time, the tendon 95 slides on the surface 17 of the bone plate 10. If unacceptable friction occurs between the tendon 95 and the surface 17 of the bone plate 10, inflammation of the tendon 95 or tearing of the tendon 95 occurs.

In the bone plate 10 of the present invention, the low friction coating layer 15 is formed on the portion C where the surface 17 of the bone plate 10 and the tendon 95 are in contact with each other. Thereby, the friction coefficient between the surface 17 and the tendon 95 becomes small. Therefore, friction when the tendon 95 slides on the surface 17 is remarkably reduced, and inflammation and tearing of the tendon 95 can be effectively suppressed.
In the present specification, the “low friction coating layer 15” is a layer having a small coefficient of friction against soft tissues of the living body such as tendons 95 and muscles 94.

Thus, in the bone plate 10 of the present invention, the friction coefficient of the surface 17 against the tendon 95 can be lowered by forming the low friction coating layer 15 on the surface 17 of the portion C of the bone plate 10. Therefore, the friction against the tendon 95 can be suppressed while the bone plate 10 has an appropriate strength (that is, not a low profile bone plate as in Patent Document 1).
Further, the bone plate 10 of the present invention includes the low friction coating layer 15 having a friction coefficient with a soft tissue lower than that of the mirror-finished surface as in Patent Document 2. Therefore, the bone plate 10 of the present invention has a higher effect of suppressing inflammation and tearing of the tendon 95 than the mirror-finished bone plate.

From the viewpoint of reducing friction, the low friction coating layer 15 is preferably formed on the entire portion C where the tendon 95 and the bone plate 10 are in contact with each other. However, from the viewpoint of the deposition cost of the low friction coating layer 15, it is desirable to form the low friction coating layer 15 at least in the region C ₁ (the region located at the distal edge of the portion C). As will be described later, since the distal edge protrudes most to the surface 17 side in the bone plate 10, the friction between the distal edge and the tendon 95 is the strongest. Therefore, even just locally form a low-friction coating layer 15 on the distal edge area C _1, it is possible to suppress the incidence of inflammation and rupture of the tendon 95.

  In FIG. 2, the FPL is illustrated as the tendon 95. However, the low-friction coating layer 15 can also be formed on a portion that contacts the tendon that may slide on the surface 17 of the bone plate 10 (for example, a portion D that may contact the deep flexor tendon). .

  In the following first to third embodiments, the position where the low friction coating layer 15 is formed will be specifically described with reference to FIGS.

(Embodiment 1)
In the present embodiment, the low friction coating layer 15 is formed at least on the surface of the distal edge 10DE of the distal end 10D (FIGS. 4 and 5). As understood from FIG. 5, the distal edge portion 10DE protrudes most on the surface 17 side in the bone plate 10. Therefore, when the tendon 95 slides on the surface 17 of the bone plate 10, the distal edge 10 DE rubs the tendon 95 most strongly. Therefore, the incidence of inflammation and tearing of the tendon 95 at the position in contact with the distal edge 10DE is higher than the incidence at other positions.

Therefore, as shown in FIGS. 4 and 5, a low friction coating layer 15 is locally formed on the surface of the distal edge 10DE, and the friction coefficient between the surface of the distal edge 10DE and the tendon 95 is locally increased. The effect of suppressing the inflammation and tearing of the tendon 95 is extremely high (compared to forming the low-friction coating layer 15 locally at other sites).
In particular, when the material used for the low friction coating layer 15 is expensive, the low friction coating layer 15 is locally formed only on the distal end portion 10DE, thereby reducing the cost of the bone plate 10 and reducing the tendon 95. The incidence of inflammation and tearing can be reliably reduced.

As shown in FIG. 2, the low friction coating layer 15 can be formed only in the region C ₁ that slides with the tendon 95. On the other hand, as shown in FIG. 4, the low friction coating layer 15 can be formed over the entire width of the distal edge 10DE. The low friction coating layer 15 as shown in FIG. 4 increases the deposition cost, but the position and width of the tendon 95 differ depending on the physique of the patient, or when the position of the tendon 95 is moved by surgery. There is an advantage that can also respond.

(Embodiment 2)
In the present embodiment, the low friction coating layer 15 is formed not only on the distal edge 10DE but also on the entire surface 17D of the distal end 10D (FIGS. 6 and 7). The tendon 95 is mainly located on the distal D side of the boundary L _DP between the distal end portion 10D and the proximal end portion 10P. Therefore, when the friction coefficient between the surface 17D of the distal end 10D and the tendon 95 is reduced by forming the low friction coating layer 15 on the surface 17D of the distal end 10D, the friction received by the tendon 95 is reduced. It can be greatly reduced. Therefore, the incidence of tendon inflammation and tearing can be further reduced.

(Embodiment 3)
In the present embodiment, the low friction coating layer 15 is also formed on the surface 17P of the proximal end portion 10P (FIGS. 8 and 9). The tendon 95 is connected to the muscle 94 on the proximal P side of the boundary L _DP between the distal end portion 10D and the proximal end portion 10P. Therefore, when the low friction coating layer 15 is formed on the surface 17D of the distal end portion 10D, friction between the tendon 95 and the surface 17D can be reduced, and friction between the muscle 94 and the surface 17D can be reduced. Since the muscle 94 strongly contacts the surface 17D when contracted, the muscle 94 receives a stimulus from the surface 17D. Depending on the degree of stimulation, the muscle 94 may become inflamed. Here, when the low-friction coating layer 15 is formed on the surface 17D, the stimulation received by the muscle 94 is reduced, so that the generation of inflammation of the muscle 94 can be suppressed.
As described above, when the low friction coating layer 15 is formed on the surface 17P of the proximal end portion 10P, not only the effect of suppressing inflammation and tearing of the tendon 95 but also the effect of suppressing the generation of inflammation of the muscle 94 is achieved. can get.

  The bone plate 10 of the third embodiment has the highest friction reducing effect on the tendon 95. On the other hand, the film formation cost for forming the low friction coating layer 15 is the lowest in the bone plate 10 of the first embodiment. Therefore, it is preferable to select the bone plate 10 according to any one of the first to third embodiments in consideration of the lifestyle of the patient (frequency of use of fingers) and the presence or absence of removal of the bone plate 10.

Next, screw holes formed in the bone plate 10 will be described.
Referring to FIG. 1 again, the bone plate 10 has a plurality of screw holes. The distal end portion 10D is formed with a female screw hole 51 in which a female screw is formed and a counterbore screw hole 54 in which a counterbore is formed. The proximal end portion 10P is formed with a ball seat screw hole 52 in which a ball seat is formed and a sliding elongated hole 53 extending in the longitudinal direction of the proximal end portion 10P. Moreover, the wire hole 55 for inserting K wire can be provided in the distal end part 10D and the proximal end part 10P as needed.

In the bone plate 10 of the present invention, the low friction coating layer 15 is also formed on the inner surface of the screw holes (internal screw hole 51, ball seat screw hole 52, sliding long hole 53 and counterbore screw hole 54) formed in the bone plate 10. Is preferably formed.
Since the portion where the surface 17 of the bone plate 10 and the inner surfaces of the screw holes 51 to 54 are in contact is an edge (FIG. 1B), the tendon 95 may be caught by the edge and damaged. Therefore, by providing the low friction coating layer 15 on the inner surfaces of the screw holes 51 to 54 and covering the edges with the low friction coating layer 15, it is possible to suppress the tendon 95 from being caught by the edges.

For example, as shown in FIG. 6, when the low friction coating layer 15 is formed on the surface 17D of the distal end portion 10D, the inner surfaces of the screw holes 51 and 54 formed in the distal end portion 10D are coated with the low friction coating. Covering with the layer 15 is preferable because the low friction coating layer 15 can be formed simultaneously.
Further, as shown in FIG. 8, when the low friction coating layer 15 is formed on the surface 17P of the proximal end portion 10P, the inner surface of the screw holes 52 and 53 formed in the proximal end portion 10P is also low. Covering with the friction coating layer 15 is preferable because the low friction coating layer 15 can be formed simultaneously.

  The back surface 19 of the bone plate 10 is preferably roughened. As the fracture heals, osteoblasts proliferate around the fracture. Since these osteoblasts enter into the rough concave portion of the rough surface, the bonding force between the fracture portion and the bone plate can be increased. The back surface 19 is preferably roughened so that the maximum height of the surface roughness is greater than 1 μm.

Next, a bone pin and a bone screw used to fix the bone plate 10 to the fracture site of the rib 90 will be described.
The bone pin 80 of FIG. 10 is used to fix the female screw hole 51 to the rib 90. The head 81 of the bone pin 80 is formed with a male screw that engages with the female screw of the female screw hole 51. A shaft 85 extends from the head 81 of the bone pin 80. When the head 81 of the bone pin 80 is screwed into the female screw hole 51, the bone pin 80 is fixed to the bone plate 10. Thereby, the bone plate 10 can be stably fixed to the rib 90 into which the shaft 85 of the bone pin 80 is inserted without swinging or turning.

The bone screw 70 of FIG. 11 is used to fix the sliding slot 53 and counterbore screw hole 54 to the rib 90. Since the lower surface of the head 71 of the bone screw 70 is flattened, it is suitable for engaging with a spot facing.
The bone screw 76 of FIG. 12 is suitable for fixing the ball seat screw hole 52 to the rib 90. Since the seating surface of the ball seat screw hole 52 is a curved surface, the countersunk head 77 of the bone screw 76 can swing within the ball seat. Therefore, the bone screw 76 can be screwed into the rib 90 at an arbitrary angle. Note that the head 71 such as the bone screw 70 can be used for fixing the ball seat screw hole 52 as long as it can swing within the ball seat.
These bone screws 70 and 76 are provided with a shaft 75 in which male screws are formed. The shaft 75 is preferably capable of self-tapping.

  For example, hexagonal holes 83 and 73 can be provided on the top surfaces of the heads 81, 71 and 77 of the bone pin 80 and the bone screws 70 and 76, and can be rotated by a hexagonal screwdriver. The hexagonal holes 83 and 73 can be changed to holes having different shapes, for example, a slot, a cross hole, a square hole, or a hexalobe hole can be adopted. In particular, it is preferable to use a hexagonal hole or a hexalobe hole because it is suitable for reliably transmitting a large torque.

  The low friction coating layer 15 is formed on the upper surfaces 81u, 71u, 77u of the heads 81, 71, 77 of the bone pins 80 and the bone screws 70, 76. If the upper surface 81u, 71u, 77u protrudes from the surface 17 of the bone plate 10 after fixing the bone plate 10 to the rib 90, the tendon 95 may be rubbed against the upper surface 81u, 71u, 77u, causing inflammation or tearing. There is. The bone pin 80 and the bone screws 70 and 76 of the present invention are formed by forming the low friction coating layer 15 on the upper surfaces 81u, 71u and 77u, thereby suppressing the tendon 95 from being rubbed by the upper surfaces 81u, 71u and 77u. 95 inflammation and rupture can be suppressed.

One form of the present invention is a fixation system for fixing a fracture site of a distal radius portion from the palm side, and includes a bone plate 10 and bone pins 80 and / or bone screws 70 and 76. Features.
In this fixation system, the low friction coating layer 15 is formed on the surface 17 of the bone plate 10 and the upper surface 81 u of the bone pin 80 and / or the upper surfaces 71 u and 77 u of the bone screws 70 and 76. When the tendon 95 slides on the surface of the bone plate 10 after fixing the bone plate 10, the bone plate 10, the bone pin 80, and the bone screws 70 and 76 can be prevented from being damaged.

  Below, the material suitable for each structural member is explained in full detail.

<Low friction coating layer 15>
The low friction coating 15 formed on the bone plate 10, the bone pin 80, and the bone screws 70, 76 is preferably formed from a material having a low coefficient of friction with respect to living soft tissues such as tendons 95 and muscles 94. As a material for forming the low friction coating layer 15, a phosphorylcholine group-containing polymer and a fluorine-based polymer are suitable.

A phosphorylcholine group-containing polymer (for example, MPC) has a biological membrane-like structure and is excellent in biological safety. This polymer is known to be formed on the sliding surface of an artificial joint, and is characterized by a low coefficient of friction with a hard material in an environment where a large amount of body fluid exists (for example, in a joint capsule).
In the present invention, the phosphorylcholine group-containing polymer is newly found to have a very low coefficient of friction with a soft tissue such as tendon 95 in an environment where a small amount of interstitial fluid exists (for example, between bone and tendon). Is used as a material for the low-friction coating layer 15 of the bone plate 10.

  The phosphorylcholine group-containing polymer has an effect of suppressing tissue adhesion in the body. As described above, when the tendon 95 is inflamed or ruptured, the tissue of the tendon 95 spreads while growing on the surface 17 of the bone plate 10 and adheres to the soft tissue when reaching the surrounding soft tissue. Here, when the low friction coating layer 15 made of a phosphorylcholine group-containing polymer is formed on the surface 17 of the bone plate 10, the tissue of the tendon 95 is suppressed from growing on the surface 17 of the bone plate 10. Adhesion with surrounding soft tissue is reduced.

  The low friction coating layer 15 made of a phosphorylcholine group-containing polymer preferably has a thickness of 1 to 100 nm. If the thickness is less than 1 nm, the friction coefficient of the low friction coating layer 15 against the tendon 95 is not sufficiently lowered, which is not preferable. On the other hand, when the thickness exceeds 100 nm, the effect of reducing the friction coefficient does not increase so much, whereas the consumption of the expensive phosphorylcholine group-containing monomer that is the raw material increases, so the cost effectiveness decreases. It is not preferable.

In addition, the thickness (1-100 nm) of the low friction coating layer 15 (made of phosphorylcholine group-containing polymer) in the bone plate 10 of the present invention is the thickness of the phosphorylcholine group-containing polymer layer used for conventionally known artificial joints. Thin (100 to 200 nm).
In a conventional artificial joint, the phosphorylcholine group-containing polymer layer is formed on a surface on which a hard member (for example, a ceramic artificial bone head) is repeatedly slid in a state where a load exceeding several tens of kg is applied. Therefore, in order to improve wear resistance, a thickness of 100 to 200 nm is desirable.
On the other hand, in this invention, it forms in the surface which slides a soft tissue repeatedly in the state of applying a load of less than 1 kg. Therefore, the wear resistance is not so required, and a thickness of 1 to 100 nm is desirable as described above.

  Examples of the phosphorylcholine group-containing polymer include 2-methacryloyloxyethyl phosphorylcholine (MPC), 2-acryloyloxyethyl phosphorylcholine, 4-methacryloyloxybutylphosphorylcholine, 6-methacryloyloxyhexylphosphorylcholine, ω-methacryloyloxyethylene phosphorylcholine, 4-styryloxybutyl. Phosphorylcholine can be used.

The fluoropolymer, which is another material suitable for the low friction coating layer 15, has high biosafety because of low reactivity. The fluoropolymer has a very small coefficient of friction against soft tissues such as tendons 95. In addition, the fluorine-based polymer also has an effect of suppressing tissue adhesion in the body. When the low-friction coating layer 15 made of a fluoropolymer is formed on the surface 17 of the bone plate 10, the tissue of the tendon 95 is suppressed from growing on the surface 17 of the bone plate 10. The adhesions are reduced.
In addition, since the fluoropolymer can be formed at a lower cost than the phosphorylcholine group-containing polymer, the cost of the bone plate 10 can be suppressed.

  The low friction coating 15 made of a fluorine-based polymer preferably has a thickness of 0.1 to 20 μm. If the thickness is less than 0.1 μm, the adhesion of the fluoropolymer is insufficient, and pinholes are generated in the low friction coating layer 15, which is not preferable. On the other hand, if the thickness exceeds 20 μm, it is not preferable because poor drying tends to occur during film formation and the thickness tends to become non-uniform.

  Fluoropolymers can be obtained by homopolymerization of fluorine-containing monomers such as tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, trifluoroethyleneter, vinylidene fluoride, vinyl fluoride, or copolymerization with other monomers. Fluorine-containing polymers can be used.

<Bone plate 10>
The bone plate 10 is formed from a metal with high biological safety such as titanium alloy, cobalt-chromium alloy, and stainless steel.
The bone plate 10 preferably has a thickness of 1.5 mm to 2.5 mm. A thickness of less than 1.5 mm is not preferable because the strength of the bone plate 10 is reduced and the bone plate 10 is easily broken. If the thickness exceeds 2.5 mm, the risk of hindering the sliding movement of the tendon 95 is relatively high, which is not preferable.

<Bone pin 80, bone screws 70, 76>
The bone pin 80 and the bone screws 70 and 76 are formed from a metal having high biological safety such as titanium alloy, cobalt-chromium alloy, and stainless steel.

  Next, a method for forming the low friction coating layer 15 on the bone plate 10 will be described in detail. Note that the method of forming the low friction coating layer 15 on the upper surfaces 81u, 71u, 77u of the bone pin 80 and the bone screws 70, 76 is the same as the method of forming the low friction coating layer 15 on the bone plate 10, and is omitted. .

<A: Low friction coating layer 15 made of phosphorylcholine group-containing polymer>
The phosphorylcholine group-containing polymer is difficult to bond directly to a metal material such as the bone plate 10. Therefore, it is preferable to strongly bond the surface 17 of the bone plate 10 and the phosphorylcholine group-containing polymer layer (low friction coating layer) 15 using the adhesive layer 22 (FIG. 13).

The method for forming the phosphorylcholine group-containing polymer layer 15 via the adhesive layer 22 includes the following three steps.
(Step A1) Surface treatment of bone plate 10 (Step A2) Formation of adhesive layer 22 (Step A3) Formation of phosphorylcholine group-containing polymer layer 15 These steps will be described sequentially.

(Step A1) Surface Treatment of Bone Plate 10 In this step, the surface 17 of the metal bone plate 10 is treated to form a hydroxyl group-containing layer (surface treatment layer 21) on the surface 17. The surface treatment performed in this step is an oxidation treatment of the metal surface by acid treatment (nitric acid treatment), plasma treatment (oxygen plasma treatment) or the like. The surface treatment layer 21 is formed on the surface 17 by binding water molecules (for example, water molecules in the air) to the oxidized surface 17.
In addition, although a titanium alloy, a cobalt-chromium alloy, and stainless steel are mentioned as a material suitable for the bone plate 10, These materials can form the surface treatment layer 21. FIG.

(Step A2) Formation of Adhesive Layer 22 In this step, a silane coupling agent is brought into contact with the surface treatment layer 21 of the bone plate 10 to form an adhesion layer 22 made of silica on the surface treatment layer 21. A silane coupling agent is a compound in which a plurality of hydrolyzable groups (for example, alkoxy groups) and reactive functional groups (for example, methacryloyl groups) are bonded to silicon atoms. In this step, first, the hydrolyzable group of the silane coupling agent undergoes a hydrolysis reaction to generate a plurality of silanol groups (Si—OH), and then one silanol group and the hydroxyl group of the surface treatment layer 21 are dehydrated and degenerated. The surface treatment layer 21 and the silane coupling agent are bonded by reaction. Further, the remaining silanol groups react with silanol groups of other silane coupling agents to dehydrate and degenerate to form a silica layer. As these reactions proceed continuously, a bonding layer 22 made of a silica layer is formed on the surface treatment layer 21. Since a covalent bond is formed between the surface treatment layer 21 and the adhesive layer 22, the bonding layer 22 is strongly bonded to the surface treatment layer 21. Moreover, the reactive functional group contained in the silane coupling agent is present on the surface of the bonding layer 22 in an unreacted state.

(Step A3) Formation of Phosphorylcholine Group-Containing Polymer Layer 15 In this step, the phosphorylcholine group-containing polymer layer 15 is formed on the adhesive layer 22 formed on the surface 17 of the bone plate 10. In the presence of a photopolymerization initiator, when the surface of the adhesive layer 22 is brought into contact with a phosphorylcholine group-containing monomer and irradiated with ultraviolet light, the reactive functional group (for example, methacryloyl group) on the surface of the adhesive layer 22 and the phosphorylcholine group-containing monomer The contained functional group (for example, methacryloyl group) is bonded. Further, the phosphorylcholine group-containing monomer is polymerized with other phosphorylcholine group-containing monomers to form a phosphorylcholine group-containing polymer layer. In this way, the phosphorylcholine group-containing polymer layer 15 is formed on the surface of the adhesive layer 22.
In addition, a photoinitiator can be mixed with the silane coupling agent of process A2.

  The phosphorylcholine group-containing polymer layer 15 thus obtained is firmly bonded to the surface 17 of the bone plate 10 via the adhesive layer 22 made of silica.

<B: Low friction coating layer 15 made of fluoropolymer>
The fluoropolymer is difficult to bond directly to a metal material such as the bone plate 10. Therefore, it is preferable to strongly bond the surface 17 of the bone plate 10 and the fluoropolymer layer (low friction coating layer) 15 using the adhesive layer 22 (FIG. 14).

The method for forming the low friction coating layer 15 via the adhesive layer 22 includes the following three steps.
(Step B1) Surface treatment of bone plate 10 (Step B2) Formation of adhesive layer 22 (Step B3) Formation of fluoropolymer layer 15 Step B1 is the same as the formation step A1 of the phosphorylcholine group-containing polymer layer, and is therefore omitted. . Below, process B2-B3 is demonstrated.

(Step B2) Formation of Adhesive Layer 22 In this step, the adhesive layer 22 is formed on the surface treatment layer 21 by bringing the coupling agent into contact with the surface treatment layer 21 of the bone plate 10. As the coupling agent, a silane coupling agent, a titanate coupling agent, a zircoaminate coupling agent, or the like can be used. The reaction mechanism between these coupling agents and the surface treatment layer 21 is as described in the step A2.
The coupling agent can be brought into contact with the surface treatment layer 21 by a method such as immersion, roll coating, spray coating, or brush coating of a stock solution or a diluted solution.

(Step B3) Formation of Fluoropolymer Layer 15 In this step, the fluoropolymer layer 15 is formed on the adhesive layer 22 formed on the surface 17 of the bone plate 10. A fluoropolymer is applied to the adhesive layer 22 by dipping, roll coating, spray coating, brush coating, or the like, and baked at 250 to 400 ° C. In this way, the fluoropolymer layer 15 is formed on the surface of the adhesive layer 22.

  The fluoropolymer layer 15 thus obtained is firmly bonded to the surface 17 of the bone plate 10 via the adhesive layer 22.

DESCRIPTION OF SYMBOLS 10 Bone plate 10D Distal end part 10P Proximal end part 15 Low friction coating layer 17, 17D, 17P Bone plate surface 19 Bone plate back surface 21 Surface treatment layer 22 Adhesive layer 51, 52, 53, 54 Screw hole 80 Bone Pin 70, 76 Bone screw 90 Radius 90D End of bone 90P End of shaft 94 Muscle 95 Tendon D Distal P Proximal L _DP Distal end and proximal boundary

Claims (13)

A bone plate for fixing the fracture site of the distal radius fracture from the palm side,
A bone plate, wherein a low friction coating layer is formed at a portion where the surface of the bone plate and the tendon are in contact with each other.   The bone plate according to claim 1, wherein the low friction coating layer is formed at least on a distal edge of a distal end portion.   The bone plate according to claim 2, wherein the low friction coating layer is further formed on a surface of the distal end portion.   The bone plate according to claim 2 or 3, wherein the low friction coating layer is further formed on a surface of a proximal end portion. The bone plate is formed with a screw hole for inserting a bone screw,
The bone plate according to any one of claims 2 to 4, wherein the low friction coating layer is further formed on an inner surface of the screw hole.   The bone plate according to any one of claims 1 to 5, wherein the low friction coating is a phosphorylcholine group-containing polymer.   The bone plate according to claim 6, wherein the thickness of the low friction coating is 1 to 100 nm.   The bone plate according to any one of claims 1 to 5, wherein the low friction coating is a fluoropolymer.   The bone plate according to claim 8, wherein the thickness of the low friction coating is 0.1 to 20 μm. A bone screw for fixing the bone plate according to any one of claims 1 to 9 to a fracture site,
A bone screw characterized in that a low friction coating layer is formed on the upper surface of the head of the bone screw.   The bone screw according to claim 10, wherein the low friction coating is a phosphorylcholine group-containing polymer.   The bone screw according to claim 10, wherein the low friction coating is a fluoropolymer. A fixation system for fixing the fracture site of the distal radius from the palm side,
The bone plate according to any one of claims 1 to 9,
The bone screw according to any one of claims 10 to 12,
A fixing system characterized by comprising:

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