JP5588876B2 - Bone screw set - Google Patents

Description

  The present invention relates to a bone screw set capable of performing osteosynthesis of a fracture site or an osteotomy site without destroying a bone fixation screw made of a biodegradable absorbable polymer.

  In recent years, osteosynthesis of fracture sites and osteotomy sites has been performed in the following manner using, for example, a bone fixing screw and an osteosynthesis plate made of a biodegradable absorbable polymer.

  First, a template is formed on a fracture site or an osteotomy site fixed with a fixing device so as not to move, and the osteosynthesis plate is bent using the template as a guide. This osteosynthesis plate is placed on the planned fixation position so as to straddle the fracture site or osteotomy site, and a bone hole is drilled at a location corresponding to the screw insertion hole on one side of the osteosynthesis plate. Taps are formed in the holes. Then, a bone fixing screw made of a biodegradable absorbable polymer is screwed into the bone hole in which the tap is formed from a screw insertion hole on one side of the osteosynthesis plate, and one side of the osteosynthesis plate is temporarily fixed.

  Next, a bone hole is drilled at a position corresponding to the screw insertion hole on the opposite side of the osteosynthesis plate. Similarly, a tap is formed in the bone hole with a dedicated tap, and then the biodegradable absorbable polymer is formed in the bone hole. Then, the bone fixing screw is screwed through the screw insertion hole on the opposite side of the osteosynthesis plate, and the opposite side of the osteosynthesis plate is also temporarily fixed.

  When temporary fixation is completed, release the fixation of the fracture site or osteotomy site with the fixation device, and once loosen the bone fixing screw, the position of the bone (bone fragment) on both sides of the fracture site or osteotomy site as necessary Correct or adjust. Then, the bone fixing screw is strongly tightened again, and the osteosynthesis plate is permanently fixed to complete the osteosynthesis.

  In the above osteosynthesis, for example, a screw or plate made of polylactic acid previously developed by the present applicant is used as a bone fixation screw or osteosynthesis plate, and as a dedicated tap, for example, at the tip of a driver shaft. A driver type with a tap is used. Further, a tap member (for example, Patent Document 1) having a tap portion formed at the tip of the shaft portion may be used, and the tap member may be screwed into the bone hole with a screwdriver to form a tap.

JP 2003-290245 A

  When osteosynthesis is performed by a conventional method, a bone fixation screw made of a biodegradable absorbable polymer is screwed in to temporarily fix the osteosynthesis plate, and both bones (bone fragments) at the fracture site or osteotomy site are fixed. In order to correct or adjust the positional relationship, it is necessary to loosen the bone fixing screw once and then tighten the bone fixing screw again to fix the bone, but tighten the bone fixing screw made of biodegradable polymer. Each time you loosen or loosen the screw, the rotational torque of the driver repeatedly acts on the cross groove in the head of the bone fixation screw, so the bone fixation screw made of biodegradable polymer that is easier to break than metal screws There was a fear that the head of would be destroyed.

  The present invention has been made under the circumstances described above, and the problem to be solved is to perform osteosynthesis of a fracture site or an osteotomy site without destroying a bone fixing screw made of a biodegradable absorbable polymer. It is to provide a bone screw set that can be used.

  In order to solve the above-mentioned problems, a bone screw set according to the present invention is a set of a metal bone tap / temporary fixation screw and a bone fixation screw made of a biodegradable absorbable polymer. The diameter of the screw is 0.9 to 1.0 times the diameter of the bone tap and temporary fixing screw, and the root diameter of the bone fixing screw is 1.0 times the diameter of the bone tap and temporary fixing screw. The shaft length excluding the head of the bone fixing screw is less than one time the shaft length excluding the head of the bone tapping and temporary fixing screw, and the pitch of the bone fixing screw and the bone tapping The pitch of the temporary fixing screws is the same.

  In the bone screw set of the present invention, the rotating tool fitting portion formed on the head of the bone tapping and temporary fixing screw and the rotating tool fitting portion formed on the bone fixing screw head are the same. It is preferable. Here, “the same” of the rotating tool fitting portions indicates substantially the same, and includes a slight difference in dimensions in the cross-sectional shape.

  In the bone screw set of the present invention, since the crest diameter, valley diameter, axial length, and pitch of the bone tap / temporary fixing screw and the bone fixing screw are in the above dimensional relationship, the bone tap / temporary fixing screw is tapped. The bone fixing screw can be securely and firmly screwed into the bone hole formed with the above. In addition, as will be described in detail later, a metal bone tap / temporary fixing screw is used to form a tap, and at the same time, a bone fixing plate is temporarily fixed, and the bone tap / temporary fixing screw is temporarily loosened and joined. After correcting or adjusting the positional relationship between both bones (bone fragments), the bone tap and temporary fixing screw can be finally removed and fixed with a bone fixing screw made of biodegradable absorbable polymer. It becomes unnecessary to tighten or loosen the bone fixing screw as in the conventional case, and the fear of damaging the head of the bone fixing screw can be solved.

  The bone screw set in which the rotating tool fitting portion formed on the head of the bone tap and temporary fixing screw and the rotating tool fitting portion formed on the head of the bone fixing screw are the same. There is an advantage that both the bone tap / temporary fixing screw and the bone fixing screw can be screwed with a common rotating tool having a tip portion that can be fitted into the fitting portion.

1 shows a bone screw set according to an embodiment of the present invention, wherein (a) is a plan view of a bone tap and temporary fixing screw, (b) is a side view of the bone tap and temporary fixing screw, and (c). Is a plan view of a bone fixing screw, and (d) is a side view of the bone fixing screw. It is explanatory drawing of one usage method of the same bone screw set, Comprising: The place which temporarily fixed one end part of the plate for osteosynthesis with the bone tap and temporary fixing screw is shown. It is explanatory drawing of one usage method of the bone screw set, Comprising: The place which both ends of the osteosynthesis plate were temporarily fixed with the bone tap and temporary fixing screw is shown. It is explanatory drawing of one usage method of the bone screw set, Comprising: The place which loosened the bone tap and temporary fixing screw of the both ends of the osteosynthesis plate, and showed the place which corrected the positional relationship of both bones. It is explanatory drawing of one usage method of the screw set for bones, Comprising: The bone tap and temporary fixing screw of both ends of the osteosynthesis plate are tightened again, and the bone hole corresponding to the other screw insertion hole of the osteosynthesis plate Shows where the tap is formed. It is explanatory drawing of one usage method of the screw set for bones, Comprising: The place which screwed the fixing screw for bones into the other bone hole which formed the tap is shown. It is explanatory drawing of one usage method of the screw set for bones, Comprising: The bone tap and temporary fixing screw of the both ends of an osteosynthesis plate are removed, and a bone fixation screw is screwed in and replaced with an osteosynthesis plate. It shows where the bone fixation has been completed and the bone joint has been completed. It is a top view which shows an example of an osteosynthesis plate.

  The bone screw set shown in FIG. 1 is a set of a metal bone tap and temporary fixing screw 1 and a bone fixing screw 2 made of a biodegradable absorbable polymer, the bone tap and temporary fixing screw. 1, a head 1a is formed so that an osteosynthesis plate or the like can be temporarily fixed to a fracture site or an osteotomy site, and the head 1a has a hexagonal hole shape into which a tip of a rotating tool (driver) is fitted. The rotating tool fitting portion 1b is formed. A thread 1d having a tapping function is formed on the shaft portion 1c excluding the head 1a of the bone tap / temporary fixing screw 1.

  The metal material of the bone tap / temporary fixing screw 1 is not particularly limited, but the bone tap / temporary fixing screw 1 frequently repeats the operation of screwing and loosening, so that the hexagonal hole-shaped rotating tool of the head 1a is used. The fitting portion 1b is preferably made of a relatively soft metal, such as SUS316, which is difficult to break.

  On the other hand, the bone fixing screw 2 made of a biodegradable absorbable polymer is for fixing an osteosynthesis plate or the like to a fracture site or an osteotomy site. The head 2a has a rotating tool (driver). A rotating groove fitting portion 2b having a cross groove shape for fitting the tip is formed, and the screw thread 2d is the same as the screw thread 1d of the bone tap and temporary fixing screw 1 on the shaft portion 2c excluding the head portion 2a. The pitch is formed.

  The cross groove-shaped rotator fitting portion 2b of the head 2a is the same as the rotator fitting portion 1b of the hexagonal hole-shaped rotator fitting portion 1b of the bone tapping and temporary fixing screw 1 (however, the depth is a little). It may be changed to a shallow one), and in this way, a bone tapping and temporary fixing screw is used with a common rotating tool having a hexagonal column-shaped tip that can be fitted to the rotating tool fitting portions 1b and 2b. 1 and the bone fixing screw 2 can be screwed together, which is preferable. On the contrary, the hexagonal hole-shaped rotary tool fitting portion 1b of the bone tap and temporary fixing screw 1 is fitted with the same rotary tool fitting as the cross groove-shaped rotary tool fitting portion 2b of the bone fixing screw 2. In this case, both screws 1 and 2 can be screwed with a common rotating tool having a cross-shaped tip that can be fitted to the rotating tool fitting portions 1b and 2b. preferable.

  The biodegradable absorbable polymer used as the material for the bone fixation screw 1 is a polylactic acid or lactic acid-glycolic acid copolymer having an initial viscosity average molecular weight of about 150,000 to 600,000, preferably about 200,000 to 550,000. Are preferably used, and further, these polymers contain 10 to 60% by mass of a bioabsorbable non-fired hydroxyapatite and the like so that they can be completely replaced with bone tissue relatively early. More preferably used.

  The bone fixing screw 2 made of the biodegradable absorbable polymer or bioceramic powder-containing polymer as described above is manufactured by cutting a molded body obtained by melt-molding these polymers into the screw shape shown in FIG. However, in order to improve the strength, the molded product is further uniaxially stretched about 2 to 8 times and the molecular chain is stretched and oriented, or the molded product is further compression-molded to form molecules. It is preferable to manufacture by cutting a chain or crystal that is obliquely oriented from the periphery toward the center line. In particular, when the compression orientation is performed as in the latter case, it is possible to obtain a bone fixation screw 2 that is dense and has high strength against external forces and twists from various directions.

  The bone tap / temporary fixing screw 1 and the bone fixing screw 2 are set such that the respective crest diameter, trough diameter, axial length, and pitch are as follows. That is, the crest diameter D2 of the bone fixing screw 2 is 0.9 to 1.0 times the crest diameter D1 of the bone tapping / temporary fixing screw 1, and the trough diameter R2 of the bone fixing screw 2 is also the tapping bone. The root diameter R1 of the temporary fixing screw 1 is 1.0 or less, preferably 0.7 to 1.0 times, more preferably 0.9 to 1.0 times, and the head 2a of the bone fixing screw 2 is The removed axial length L2 is less than 1 time, preferably 0.7 to 0.95 times the axial length L1 excluding the head 1a of the bone tap / temporary fixation screw 1, and the pitch P2 of the bone fixation screw 2 is set. And the pitch P1 of the bone tap and temporary fixing screw 1 are the same. The shape of the thread 2d of the bone fixation screw 2 is substantially similar to that of the bone tap / temporary fixation screw 1 except that the top of the thread 2d is round. ing.

  Since the bone tap / temporary fixing screw 1 and the bone fixing screw 2 have the mountain diameter, valley diameter, axial length, and pitch set as described above, the bone tap / temporary fixing screw 1 forms a tap. The bone fixing screw 2 can be securely and firmly screwed into the bone hole.

  Next, referring to FIG. 2 to FIG. 8, an example of a bone joining method for a fracture site or an osteotomy site (hereinafter referred to as a fracture site) performed using the bone screw set and the osteosynthesis plate described above. explain.

  First, the fracture site is fixed with a fixing device, the fracture site is molded with a template, and the osteosynthesis plate is bent along the fracture site using this template as a guide. The osteosynthesis plate is made of a biodegradable and absorbable polymer similar to the bone fixing screw 2 and has four screw insertion holes 3a, 3b, 3c and 3d as shown in FIG. Since there are plates of various shapes such as L, T, X, Y, etc., the plate having the optimum shape and the number of holes is selected from among them. Bending of the osteosynthesis plate is performed by immersing the plate in heated sterilized physiological saline or applying hot air to impart plasticity to the plate.

  When the bending of the osteosynthesis plate 3 is finished, the osteosynthesis plate 3 is applied to the position to be fixed so as to straddle the fracture site 4 as shown in FIG. 2, and is close to the fracture site 4 on one side of the osteosynthesis plate 3. Corresponding to the screw insertion hole 3b, a bone hole is drilled in a bone (bone fragment) 5 on one side of the fracture site 4, and a bone tap and temporary fixing screw 1 is screwed into the bone joint plate 3 in this bone hole. A screw is inserted through the insertion hole 3b to form a tap in the bone hole, and at the same time, one side of the osteosynthesis plate 3 is temporarily fixed.

  Next, a bone hole is drilled at a position near the fracture site of the bone (bone fragment) 5 on the opposite side of the fracture site 4 corresponding to the screw insertion hole 3c on the opposite side of the osteosynthesis plate 3, and FIG. As shown in Fig. 2, the bone tap and temporary fixing screw 1 is screwed into the bone hole from the screw insertion hole 3c of the bone joining plate 3 to form a tap in the bone hole, and at the same time, the other side of the bone joining plate 3 is temporarily attached. Fix it.

  When temporary fixation of the osteosynthesis plate 3 is completed, the fixation of the fracture site by the fixation device is released, and the bone tap and temporary fixation screws 1 and 1 are once loosened as shown in FIG. The positional relationship between the bone fragments 5 and 5 is corrected or adjusted as necessary. This work is an important work that is indispensable for preventing the movement of the jawbone from being hindered when the fracture site is, for example, the jawbone.

  When the correction or adjustment of the positional relationship between the bones (bone fragments) 5 and 5 is completed, the bone tap and temporary fixing screws 1 and 1 are screwed into the bone holes 5b and 5c (see FIG. 4) again as shown in FIG. In the clamped and temporarily fixed state, the bone holes 5a and 5d are drilled by drilling in the bones (bone fragments) 5 and 5 on both sides of the fracture site 4 corresponding to the screw insertion holes 3a and 3d of the osteosynthesis plate 3. Taps are formed in the bone holes 5a and 5d. This tap formation may be performed with a bone tap and temporary fixing screw 1 or with a dedicated tap.

  Then, as shown in FIG. 6, the bone fixation screws 2 and 2 are screwed into the bone holes 5a and 5d from the screw insertion holes 3a and 3d of the bone connection plate 3, and the bone connection plate 3 is fixed. 7, the bone tapping and temporary fixing screws 1, 1 are removed, and the bone fixing screws 2, 2 are screwed into the bone holes 5 b, 5 c from the screw insertion holes 3 b, 3 c of the osteosynthesis plate 3. Then, the osteosynthesis plate 3 is permanently fixed to complete the osteosynthesis.

  As described above, when the bone screw set of the present invention is used, a tap is formed with a metal bone tap and temporary fixing screw 1, and at the same time, the osteosynthesis plate 3 is temporarily fixed, and the bone tap and temporary fixing is performed. After loosening the screw 1 and correcting or adjusting the positional relationship between both bones (bone fragments) 5 and 5 to be joined, the bone tap and temporary fixing screw 1 is finally removed and the biodegradable absorbable polymer Can be fixed with the bone fixing screw 2 made of the above, so that it is not necessary to tighten or loosen the bone fixing screw made of biodegradable absorbable polymer as in the prior art. The fear of being destroyed can be resolved.

  The osteosynthesis described above is performed using the bone screw set and the osteosynthesis plate of the present invention. However, when the osteosynthesis is performed using only the bone screw set without using the osteosynthesis plate, the osteosynthesis is substantially the same. do it. That is, one or two bone holes are drilled from one side bone (bone piece) to the other side bone (bone piece) at the fracture site, and the bone tap and temporary fixing screw 1 is screwed into the bone hole. After forming the tap and temporarily fixing the bones (bone fragments) on both sides at the same time, once loosening the bone tapping and temporary fixing screws 1 to correct or adjust the positional relationship between the bones (bone fragments) on both sides, The bone tapping and temporary fixing screw 1 is tightened to temporarily fix bones (bone fragments) on both sides. In this state, another bone hole is drilled and a tap is formed, and the bone fixing screw 2 is screwed. The bones (bone fragments) on both sides may be permanently fixed by replacing the tapping and temporary fixing screw 1 with the bone fixing screw 2. Also in this case, the metal bone tap / temporary fixing screw 1 is tightened or loosened to temporarily fix the bones (bone fragments) on both sides or correct the positional relationship. The fear that the head of the bone fixing screw 1 is destroyed can be eliminated.

  As can be understood from the above description, the bone screw set of the present invention temporarily fixes and fixes bones (bone fragments) on both sides of a fracture site or an osteotomy site with or without an osteosynthesis plate. It is very suitably used when the bone is fixed and fixed after the positional relationship between the bones on both sides is corrected or adjusted.

1 Bone Tap and Temporary Fixing Screw 1a Bone Tap and Temporary Fixing Screw Head 2 Bone Fixing Screw 2a Bone Fixing Screw Head D1 Bone Tap and Temporary Fixing Screw Diameter D2 Bone Fixing Screw Pile Diameter R1 Tall diameter of bone tapping and temporary fixing screw R2 Tall diameter of bone fixing screw L1 Axis length excluding head of bone tapping and temporary fixing screw L2 Axis length excluding head of bone fixing screw P1 Pitch of bone tapping and temporary fixing screw P2 Pitch of bone fixing screw

Claims (2)

  A set of a metal bone tap / temporary fixation screw and a bone fixation screw made of biodegradable absorbable polymer, wherein the bone fixation screw has a crest diameter of 0 as the bone tap / temporary fixation screw. .9 to 1.0 times, the root diameter of the bone fixing screw is 1.0 times or less of the root diameter of the bone tap and temporary fixing screw, and the axial length excluding the head of the bone fixing screw is The bone screw is characterized by being less than 1 times the axial length excluding the head of the bone tap / temporary fixation screw, and the pitch of the bone fixation screw and the pitch of the bone tap / temporary fixation screw being the same. set. According to claim 1, characterized in that the rotary tool engagement portion formed on the head portion of the rotary tool engaging portion and the bone fixation threads formed in the bone tap and temporary fixing screw head are the same bone screw set.

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