JP6486242B2 - Spinal implant - Google Patents

Description

  The present invention relates to a spinal implant for holding a fixation rod that fixes a plurality of vertebrae together.

  Conventionally, spinal implants for holding a fixation rod for fixing a plurality of vertebrae to each other are known. As such a spinal implant, for example, Patent Document 1 discloses a bone anchor (spine implant) including a receptor member (housing) and a bone engaging member (screw) inserted from above the housing. ing.

Japanese Patent No. 5437704

  By the way, if it is set as the structure which inserts a screw from the upper side of a housing like patent document 1 mentioned above, since the housing of the magnitude | size according to a screw diameter is needed, a housing cannot be made common. In addition, when trying to share the housing, the size of the housing increases.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a spinal implant that can share a miniaturized housing regardless of the diameter of the bone screw and has excellent assemblability. .

  (1) A spinal implant according to an aspect of the present invention for achieving the above object is a spinal implant for fixing a rod to a spine, and includes a screw main body portion on which an external thread is formed on an outer peripheral surface. In the case where the screw head of a bone screw that is fixed by being screwed to the spine is held in a cylindrical shape from the outside, the direction in which the screw main body extends with respect to the screw head is the lower side, A screw head holding part having a cylindrical part formed with a support part for supporting the screw head from below, and the screw head holding part in a state of holding the screw head inside, A housing in which an engaging portion formed on the screw head holding portion engages with an inner peripheral surface side, and is disposed above the screw head in the housing, An insert that receives the pressing force of the rod pressed by the mating set screw and presses the screw head downward to fix the housing to the screw head, and the screw head holding portion comprises: It has a pair of holding members that sandwich the screw head in a direction perpendicular to the vertical direction, and is configured to be inserted into the housing from below the housing with the screw head housed inside.

  In this configuration, the screw head retainer, housing, and insert exert forces on each other that secure the rod against a bone screw that is secured to each spine of the patient, thereby bringing the patient's vertebrae together. Fix against.

  Specifically, in this configuration, the screw head holding portion holding the screw head is accommodated in the housing and engaged with the housing. Further, in this configuration, the insert disposed in the housing receives the pressing force of the rod fixed to the housing by the set screw screwed into the housing and presses the screw head downward, thereby It is fixed to the screw head. Thereby, the position and posture of the rod with respect to the bone screw can be fixed. And a patient's spine is mutually fixed by fixing a rod as mentioned above so that it may straddle all the bone screws fixed to each of a plurality of spines of a patient used as fixation object.

  Moreover, in this structure, the support part formed in the cylindrical part of the screw head holding part supports the screw head from the lower side. Thereby, it can prevent that a screw head falls out of a housing by a screw head holding part. Moreover, in this configuration, the screw head can be accommodated in the screw head holding portion by the pair of holding members of the screw head holding portion sandwiching the screw head from both sides.

  For example, in the case of a spinal implant that is assembled by inserting a bone screw from above the screw head holding part (or housing), the size of the housing needs to be set according to the size of the screw diameter of the bone screw. The housing cannot be shared. In addition, when trying to share the housing, the size of the housing increases.

  On the other hand, according to this configuration, the screw head is sandwiched and held by the pair of holding members, and the pair of holding members (screw head holding portions) in a state of holding the screw head is housed in the housing. The assembly process can be inserted from below. As a result, a miniaturized housing can be used in common regardless of the screw diameter.

  Further, according to this configuration, the pair of holding members (screw head holding portion) holding the screw head is inserted from the lower side of the housing, and the engaging portion formed on the screw head holding portion is By engaging with the housing, the screw head holding portion in a state where the screw head is held can be engaged with the housing. Thereby, the spinal implant excellent in assemblability can be provided.

  Therefore, according to this configuration, a miniaturized housing can be used in common regardless of the diameter of the bone screw, and a spinal implant excellent in assemblability can be provided.

  (2) Preferably, the said engaging part is an engaging convex part engaged with the recessed part formed in the internal peripheral surface of the said housing.

  In this configuration, the engaging portion that engages with the concave portion of the housing is configured as an engaging convex portion, and the engaging convex portion is fitted into the concave portion, whereby the screw head holding portion is appropriately engaged with the housing. be able to.

  (3) More preferably, a groove portion through which the engagement convex portion can pass is formed on an inner peripheral surface of the housing, and the groove portion is a groove-shaped first groove portion extending upward from a lower end of the housing; The engagement convex portion that has passed through the first groove portion is formed so as to be able to pass therethrough, and has a second groove portion as the concave portion that extends in a direction intersecting the first groove portion.

  According to this configuration, at the time of assembling the spinal implant, when the screw head holding portion holding the screw head is engaged with the housing, both are engaged as follows.

  Specifically, first, the assembly operator slides the engagement convex portion of the screw head holding portion in a state where the screw head is held inside from the lower end portion of the first groove portion, and the first groove portion and the first groove portion. Move to the position where the two grooves intersect. Thereafter, the assembly operator fits the engaging convex portion into the second groove portion as the concave portion by rotating the screw head holding portion in the direction in which the second groove portion extends. Thereby, an engagement convex part can be engaged with a recessed part. That is, according to this configuration, after the screw head holding portion holding the screw head is slid upward in the housing, the screw head holding portion is rotated in the housing to engage the screw head holding portion. The convex portion can be reliably and easily engaged with the concave portion.

  (4) Preferably, the pair of holding members have the same size and shape with respect to each other.

  According to this structure, since the member used as each of a pair of holding member can be made common, the spinal implant advantageous in terms of cost can be provided.

  (5) Preferably, the first holding member that is one of the pair of holding members has a protrusion that fits into a recess formed in the second holding member that is the other of the pair of holding members. Is formed.

  In this configuration, when assembling the spinal implant, when the screw head is held between the pair of holding members, the protrusions of one holding member fit into the recesses of the other holding member, so that both Fixed.

  For example, in the case where the recesses and the protrusions are not formed on the pair of holding members as in this configuration, the assembly operator holds the screws so that the pair of holding members held between the screw heads are not separated. Since it becomes necessary to insert the pair of holding members into the housing while pressing, the assembly process becomes complicated.

  In this regard, according to this configuration, since the pair of holding members in the state in which the screw head is held inside is engaged with each other, the assembly operator holds the pair of holding members together as described above. However, there is no need to insert it into the housing. That is, according to this structure, the spinal implant excellent in assemblability can be provided.

  (6) Preferably, the insert is formed with an insert side engaging portion that engages with the inner peripheral surface side of the housing, and the insert side engaging portion engages with the inner peripheral surface side of the housing. This restricts the circumferential movement of the insert relative to the housing.

  In this configuration, the position of the insert in the housing can be easily fixed.

  (7) Preferably, the portion of the cylindrical portion that holds the screw head is formed in a concave spherical shape, and the curvature radius thereof is the same as the radius of the screw head. Yes.

  According to this configuration, in a state where the screw head is housed inside the cylindrical portion, the screw head and the cylindrical portion are easily brought into close contact with each other. That is, according to this structure, it becomes easy to hold | maintain a screw head in a cylindrical part.

  (8) Preferably, the spinal implant further includes the bone screw.

  With this configuration, a small-sized housing can be used in common regardless of the size of the screw diameter, and the spinal implant is excellent in assemblability and can further include a bone screw.

  According to the present invention, it is possible to provide a spinal implant having a miniaturized housing that can be made common regardless of the diameter of the bone screw and excellent in assembling.

It is a disassembled perspective view of the spinal implant which concerns on this embodiment, Comprising: It is a figure shown with the fixation rod fixed to spine by this spinal implant. It is a figure which shows typically the usage condition of the spinal implant shown in FIG. It is the fragmentary sectional view which cut | disconnected the spinal implant longitudinally. FIG. 4 is a partial cross-sectional view in which a spinal implant is cut in a longitudinal direction, and is a partial cross-sectional view cut at a position different from FIG. It is a figure which shows the shape of a housing, Comprising: (A) is a top view, (B) is a front view, (C) is a bottom view, (D) is a side view. (A) is sectional drawing in the VIA-VIA line | wire of FIG. 5 (B), (B) is sectional drawing in the VIB-VIB line | wire of FIG. 5 (D). It is a figure which shows the shape of a half bearing, (A) is a top view, (B) is a side view, (C) is an arrow view in the arrow VIIC direction of FIG. 7 (B), (D) is FIG. It is sectional drawing in the VIID-VIID line of (C). It is a figure which shows the shape of a bearing part, Comprising: (A) is a top view, (B) is a front view, (C) is sectional drawing in the VIIIC-VIIIC line | wire of FIG. 8 (A). It is a figure which shows the shape of insert, Comprising: (A) is a top view, (B) is a front view, (C) is a side view, (D) is sectional drawing in the IXD-IXD line | wire of FIG.9 (C). . It is a flowchart which shows the assembly process of a spinal implant. It is a flowchart which shows the procedure which fixes a fixing rod to a patient's spine. It is a perspective view which shows typically the 1st half bearing and 2nd half bearing as a pair of half bearing which the bearing part of the spinal implant which concerns on a modification has, Comprising: (A) is a 1st half bearing. A perspective view and (B) are perspective views of the 2nd half bearing.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention can be widely applied to spinal implants for holding a fixation rod that fixes a plurality of vertebrae to each other.

  FIG. 1 is an exploded perspective view of a spinal implant 1 according to this embodiment, and is a view showing a fixation rod R fixed to the spine L by the spinal implant 1. Moreover, FIG. 2 is a figure which shows typically the usage condition of the spinal implant 1 shown in FIG. FIG. 3 is a partial cross-sectional view of the spinal implant 1 cut in the longitudinal direction. FIG. 4 is a partial cross-sectional view of the spinal implant 1 cut in the longitudinal direction, and is a partial cross-sectional view cut at a position different from that in FIG. 3.

  The spinal implant 1 is an instrument used in spinal fusion. As shown in FIG. 1, the spinal implant 1 includes a screw 2, a housing 3, a bearing portion 4 (screw head holding portion) having two half bearings 7 (holding members), an insert 5, and a set screw. 6 are provided. In the spinal implant 1, the fixing rod R is fixed to the spinal implant 1 by combining the screw 2, the housing 3, the bearing portion 4, the insert 5, and the set screw 6 to exert a force.

  Referring to FIG. 2, each spinal implant 1 is fixed to each spine L by screwing screws 2 of each spinal implant 1 to each of a plurality of adjacent spines L. Then, as shown in FIG. 2, the fixing rod R is stretched over the entire spinal implant 1 fixed to each spine L, and in this state, the set screw 6 is fixed to the housing 3. Thereby, since each spine L returned to the normal position and state can be fixed to each other, the hip bone of the patient can be maintained in a predetermined state, and the burden on the waist can be reduced.

[Configuration of each element constituting the spinal implant]
The screw 2 has the screw main-body part 2a and the screw head part 2b with reference to FIG. 1, and these are integrally formed. The screw main body 2a is provided as a screw portion having a male screw formed on the outer peripheral portion thereof. The screw head portion 2b is a portion formed in a substantially spherical shape, and is provided integrally with a portion (base end portion) opposite to the distal end portion (portion embedded in the spine L) of the screw main body portion 2a. ing.

  5A and 5B are diagrams illustrating the shape of the housing 3, in which the shape of the housing is illustrated, in which FIG. 5A is a plan view, FIG. 5B is a front view, FIG. 5C is a bottom view, and FIG. It is a side view. 6A is a cross-sectional view taken along line VIA-VIA in FIG. 5B, and FIG. 6B is a cross-sectional view taken along line VIB-VIB in FIG.

  The housing 3 is a member that is rotatably attached to the screw head 2b. Referring to FIGS. 1, 5, and 6, the housing 3 includes a base portion 11 that is a portion formed in a substantially cylindrical shape, and a pair of tab portions 12 that extend upward from the base portion 11. Are integrally formed. Between the pair of tab portions 12, a pair of slit portions 13 in which the fixing rod R is disposed is formed inside.

  Two first groove portions 14 and two second groove portions 15 are formed on the inner peripheral surface of the housing 3. Although these groove portions 14 and 15 will be described in detail later, when the spinal implant 1 is assembled, when the bearing portion 4 with the screw head 2b held therein is engaged with the housing 3, the bearings 14 and 15 are provided. The engaging convex part 25 of the part 4 is provided as a guide groove for guiding.

  As shown in FIG. 6A, each first groove portion 14 is formed in a groove shape extending upward from the lower end of the housing 3. 5B and 5C, each first groove portion 14 is formed so as to extend in a vertical direction at a portion where the slit portion 13 is formed when viewed from the vertical direction. Thereby, each 1st groove part 14 is formed in the position on the opposite side 180 degree | times centering on the axial center of the base 11 formed in the substantially cylindrical shape seeing from an up-down direction. Each first groove portion 14 is formed such that a cross section perpendicular to the longitudinal direction is an arc shape.

  Each second groove portion 15 is formed in a groove shape extending in the circumferential direction at the lower portion of the inner peripheral surface of each tab portion 12 of housing 3 with reference to FIGS. 6 (A) and 6 (B). Yes. Thereby, each 2nd groove part 15 is formed in a substantially circular arc shape seeing from an up-down direction.

  On the upper part of the inner side surface of each tab portion 12, a female screw 16 is formed that extends in a spiral shape along the vertical direction. The set screw 6 is screwed into the female screw 16.

  Further, a concave portion 17 is formed in a portion slightly below the portion where the female screw 16 is formed on the inner peripheral surface of each tab portion 12. A convex portion 36 of the insert 5 which will be described in detail later is engaged with the concave portion 17.

  7A and 7B are diagrams showing the shape of the half bearing 7, wherein FIG. 7A is a plan view, FIG. 7B is a side view, and FIG. 7C is an arrow view in the direction of arrow VIIC in FIG. FIG. 7D is a cross-sectional view taken along the line VIID-VIID in FIG. 8A and 8B are views showing the shape of the bearing portion 4, wherein FIG. 8A is a plan view, FIG. 8B is a front view, and FIG. 8C is a cross-sectional view taken along line VIIIC-VIIIC in FIG. is there.

  The bearing portion 4 is a member for preventing the screw head 2b from being detached from the housing 3, and is engaged with the inner peripheral surface side of the housing 3 with the screw head 2b held inside. ing. The bearing portion 4 is configured by combining two half bearings 7 with each other. In this embodiment, each half bearing 7 is comprised by the same member. That is, the two half bearings 7 have the same size and shape with respect to each other.

  The half bearing 7 has a bearing body portion 21 and a claw portion 22, which are integrally formed.

  The bearing main body portion 21 is a portion formed in a substantially semi-cylindrical shape, and is a portion that holds the screw head 2 b inside the half bearing 7. The inner peripheral surface of the bearing main body portion 21 is provided as a concave spherical portion 23 formed in a concave spherical shape. The radius of curvature of the concave spherical portion 23 is set to be the same as the radius of the screw head 2b.

  The claw portion 22 is for engaging the bearing main body portion 21 with the housing 3. The claw portion 22 has an extending portion 24 that extends upward from the upper end of the bearing main body portion 21 and an engaging convex portion 25 that protrudes radially outward from the distal end portion of the extending portion 24, and these are integrally formed. Has been. The extending portion 24 extends upward from the center portion in the width direction of the bearing main body portion 21.

  Further, a support portion 26 is formed in the bearing main body portion 21.

  The support portion 26 is a portion formed so as to be narrowed toward the inner peripheral side of the bearing main body portion 21 at the lower end portion of the inner peripheral portion of the bearing main body portion 21. In the state in which the screw head 2b is held inside the bearing main body 21, the support portion 26 supports the screw head 2b from below, so that the bearing portion 4 can be removed from the screw head 2b. It is for preventing.

  With reference to FIG.7 and FIG.8, the bearing part 4 is comprised by combining the half bearing 7 which has the above structures. Specifically, the bearing portion 4 is formed by bringing the mating surfaces 21a of the bearing main body portions 21 of the respective half bearings 7 into close contact with each other. In this state, the bearing portion 4 has a cylindrical portion 27 formed in a cylindrical shape by the two bearing main body portions 21 as shown in FIGS.

  9A and 9B are diagrams showing the shape of the insert 5, where FIG. 9A is a plan view, FIG. 9B is a front view, FIG. 9C is a side view, and FIG. 9D is a line IXD-IXD in FIG. FIG. The insert 5 is a member accommodated in the housing 3 and is a member that presses the screw head 2b from above by being pressed from above by the fixing rod R. The insert 5 has a base portion 31 formed in a cylindrical shape and a pair of wall portions 32 extending upward from the base portion 31, and these are integrally formed.

  The base 31 is a portion in which a through hole 33 penetrating in the vertical direction is formed. A lower curved surface portion 34 formed in a curved shape into which the upper portion of the screw head 2b is fitted is formed below the base portion 31. Further, an upper curved surface portion 35 formed in a curved shape into which the lower side of the fixed rod R is fitted is formed above the base portion 31.

  A pair of wall part 32 is provided so that it may mutually oppose. A fixing rod R is sandwiched and held between the pair of wall portions 32. A convex portion 36 that protrudes outward from the upper portion of each wall portion 32 is formed on the outer portion. These convex portions 36 are provided as insert side engaging portions that engage with the concave portions 17 of the housing 3.

  Referring to FIG. 1, the set screw 6 is provided as a screw that is flat in the vertical direction and has a male screw formed on the outer periphery. The set screw 6 is screwed into a female screw 16 formed in the housing 3.

[Assembly process of spinal implant]
FIG. 10 is a flowchart showing an assembly process of the spinal implant 1. Below, with reference to FIG. 9 etc., the assembly process of the spinal implant 1 is demonstrated.

  First, in step S1, the bearing portion 4 is engaged with the screw head 2b. Specifically, referring to FIG. 1, FIG. 3, FIG. 7 and FIG. 8, the assembly operator puts the screw head 2b between the pair of half bearings 7 so that the pair of half bearings 7 are aligned. The surfaces 21a are brought into close contact with each other. Thereby, since the concave spherical surface portion 23 of each half bearing 7 is in close contact with the screw head 2b, the screw head 2b is sandwiched and held by the bearing portion 4. Further, in this state, the support portion 26 supports the screw head 2b from below.

  Next, in step S <b> 2, the bearing portion 4 in a state where the screw head 2 b is housed inside is engaged in the housing 3. Specifically, referring to FIGS. 1, 3, and 5 to 8, first, the assembling worker has the engagement convex portion 25 of the bearing portion 4 in a state where the screw head 2 b is held inside. The bone screw 2 is held and the bearing portion 4 is inserted into the housing 3 so as to slide upward from the lower end portion of the first groove portion 14 of the housing 3. Thereafter, the assembly operator moves the engaging projection 25 of the bearing 4 along the second groove 15 by rotating the bone screw 2 in that state by 90 degrees about the central axis of the housing 3. Let Thereby, since the engaging convex part 25 of the bearing part 4 fits in the 2nd groove part 15, the bearing part 4 and the housing 3 engage.

  Next, in step S <b> 3, the insert 5 is inserted into the housing 3. At that time, the insert 5 is in a state where each convex portion 36 formed in the insert 5 and each concave portion 17 formed in the housing 3 are aligned in the vertical direction, until each convex portion 36 reaches each concave portion 17. It is inserted into the housing 3. Thereby, since each convex part 36 and each recessed part 17 engage, the insert 5 is fixed in the housing 3. In this state, the lower curved surface portion 34 of the insert 5 is in contact with the upper portion of the screw head 2b. In this state, the lower portion of the outer peripheral surface of the insert 5 is opposed to the upper portion of the inner peripheral surface of the bearing portion 4 with a slight gap or is in contact with the portion. ing.

  When the spinal implant 1 is assembled as described above, the housing 3 and the bearing portion 4 and the insert 5 accommodated in the housing 3 are rotatable with respect to the screw head 2b. Yes.

[Fixing procedure for fixing rod]
FIG. 11 is a flowchart showing a procedure for fixing the fixation rod R to the spine L of the patient.

  First, in step S4, the screw body 2a of the bone screw 2 is screwed and fixed to each of a plurality of vertebrae of a patient to be fixed by a screwdriver or the like.

  Next, in step S <b> 5, the fixed rod R is disposed on the insert 5 in the housing 3. At this time, the fixed rod R is inserted into the housing 3 so as to pass through a pair of slit portions 13 formed in the housing 3. Thereby, the fixed rod R is a portion between the pair of wall portions 32 in the insert 5 and is disposed on the upper curved surface portion 35 of the insert 5 (see FIG. 3).

  Finally, in step S6, the set screw 6 is fastened to the housing 3 with reference to FIGS. At that time, the set screw 6 gradually advances until it reaches a position to press the fixed rod R downward, and the lower end of the set screw 6 contacts the fixed rod R to press the fixed rod R downward. At this time, the screw head 2 b is pressed by the set screw 6 via the fixed rod R and the insert 5.

  In the state as described above, when the set screw 6 is further tightened, the bone screw 2 is screwed and fixed to the spine L, so that the relative relationship between the housing 3 and the bearing portion 4 is maintained. The set screw 6, the fixing rod R, the insert 5, and the bone screw 2 in the state of being pulled up are relatively lifted upward. At this time, the support portion 26 of the bearing portion 4 is caught under the screw head 2b, and the housing 3 is sandwiched and held between the set screw 6 and the screw head 2b. Accordingly, the position and posture of the fixing rod R with respect to the bone screw 2 are fixed while preventing the housing 3 from coming off from the screw head 2b.

  In the spinal fusion, the steps S4 to S6 are performed on each of the spinal implants 1 fixed to each spine, thereby fixing the plurality of spines L to each other by the fixing rod R. Can do.

[effect]
As described above, in the spinal implant 1 according to the present embodiment, the bearing portion 4, the housing 3, and the insert 5 exert forces on each other, and these are applied to the bone screw 2 fixed to each spine L of the patient. By fixing the rod R, the patient's spine L is fixed relative to each other.

  Specifically, in the spinal implant 1, the bearing portion 4 holding the screw head 2 b is accommodated in the housing 3 and engaged with the housing 3. Further, in the spinal implant 1, the insert 5 disposed in the housing 3 receives the pressing force of the fixing rod R fixed to the housing 3 by the set screw 6 screwed into the housing 3, and the screw head 2 b is moved. By pressing downward, the housing 3 is fixed to the screw head 2b. Thereby, the position and posture of the fixing rod R with respect to the bone screw 2 can be fixed. Then, the patient's spine L is fixed to each other by fixing the fixation rod R as described above so as to straddle all the bone screws 2 fixed to each of the plurality of spines L of the patient to be fixed. Is done.

  Moreover, in the spinal implant 1, the support part 26 formed in the cylindrical part 27 of the bearing part 4 supports the screw head 2b from the lower side. As a result, the screw head 2 b can be prevented from falling out of the housing 3 by the bearing portion 4. Moreover, in the spinal implant 1, the pair of half bearings 7 included in the bearing portion 4 sandwich the screw head 2 b from both sides, whereby the screw head 2 b can be accommodated in the bearing portion 4.

  For example, in the case of a spinal implant assembled by inserting a bone screw from the upper side of a washer (or housing), it is necessary to set the size of the housing according to the size of the screw diameter of the bone screw. Can not be converted. In addition, when trying to share the housing, the size of the housing increases.

  On the other hand, according to the spinal implant 1, a pair of half bearings 7 (bearings) have a configuration in which the screw head 2b is held between the pair of half bearings 7 and the screw head 2b is held. The part 4) is an assembly process that can be inserted from the lower side of the housing 3. As a result, a miniaturized housing can be used in common regardless of the screw diameter.

  Further, according to the spinal implant 1, a pair of half bearings 7 (bearing portions 4) holding the screw heads 2 b are inserted from the lower side of the housing 3, and the engagement protrusions formed on the bearing portions 4. By engaging the portion 25 with the housing 3, the bearing portion 4 in a state where the screw head 2 b is held can be engaged with the housing 3. Thereby, the spinal implant excellent in assemblability can be provided.

  Therefore, according to the spinal implant 1, the miniaturized housing 3 can be made common regardless of the diameter of the bone screw 2, and a spinal implant excellent in assemblability can be provided.

  Moreover, in the spinal implant 1, the convex part engaged with the 2nd groove part 15 of the housing 3 is comprised by the engagement convex part 25, and the bearing part 4 is fitted by fitting the engagement convex part 25 in the 2nd groove part 15. FIG. The housing 3 can be properly engaged.

  Moreover, according to the spinal implant 1, when the spinal implant 1 is assembled, when the bearing portion 4 holding the screw head 2b is engaged with the housing 3, both are engaged as follows. .

  Specifically, first, the assembly operator slides the engagement convex portion 25 of the bearing portion 4 holding the screw head portion 2b upward from the lower end portion of the first groove portion 14, and the first groove portion 14 and the first groove portion 14b. The two grooves 15 are moved to a position where they intersect. Thereafter, the assembly operator rotates the bone screw 2 about the vertical direction as the rotation axis to rotate the bearing portion 4, thereby fitting the engagement convex portion 25 into the second groove portion 15 as the concave portion. Thereby, the engagement convex part 25 can be engaged with the 2nd groove part 15. As shown in FIG. That is, according to this configuration, after the bearing portion 4 holding the screw head 2 b is slid upward in the housing 3, the bearing portion 4 is rotated in the housing 3, thereby The portion 25 can be reliably and easily engaged with the second groove portion 15.

  Moreover, according to the spinal implant 1, since the member used as a pair of half bearing 7 can be made shared, the spinal implant advantageous in terms of cost can be provided.

  In the spinal implant 1, the position of the insert 5 in the housing 3 can be easily fixed.

  Further, according to the spinal implant 1, in the state where the screw head 2b is housed inside the cylindrical portion 27, the screw head 2b and the cylindrical portion 27 are easily brought into close contact with each other. That is, according to the spinal implant 1, the screw head 2b can be easily held in the cylindrical portion 27.

  Further, in the spinal implant 1, a small housing 3 can be used in common regardless of the size of the screw diameter, and the spinal implant 1 is excellent in assemblability and further includes a bone screw 2. Can be configured.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible as long as they are described in the claims. For example, the following modifications may be made.

[Modification]
(1) FIG. 12 is a perspective view schematically showing a first half bearing 7a and a second half bearing 7b as a pair of half bearings 7a, 7b included in a bearing portion of a spinal implant according to a modification. (A) is a perspective view of the 1st half bearing 7a, (B) is a perspective view of the 2nd half bearing 7b.

  In this modification, the configuration of the pair of half bearings is different from that in the above embodiment. Below, about the half bearings 7a and 7b of this modification, a different point from the half bearing 7 of the said embodiment is demonstrated, and description is abbreviate | omitted about another part.

  The pair of half bearings 7a and 7b included in the spinal implant according to the present modification has different shapes with respect to each other.

  One of the pair of half bearings 7a and 7b is provided as a first half bearing 7a (first holding member). The first half bearing 7a has substantially the same size and shape as the half bearing 7 of the above embodiment. However, unlike the half bearing 7 of the above embodiment, the first half bearing 7a is formed with a protruding portion 28 that protrudes from the mating surface 21a of the first half bearing 7a.

  The protrusion 28 is formed on each of the two mating surfaces 21a of the first half bearing 7a. The protrusion 28 is formed so as to protrude from the upper end portion of each mating surface 21a toward the counterpart half bearing 7b.

  The other of the pair of half bearings 7a and 7b is provided as a second half bearing 7b (second holding member). The second half bearing 7b has substantially the same size and shape as the half bearing 7 of the above embodiment. However, unlike the half bearing 7 of the above embodiment, the second half bearing 7b is formed with a recess 29 that is recessed from the mating surface 21a of the first half bearing 7a.

  The recess 29 is formed on each of the two mating surfaces 21a of the second half bearing 7b. The recess 29 is formed so as to be recessed from the upper end portion of each mating surface 21a. The recess 29 is formed to have a shape complementary to the protrusion 28.

  According to the spinal implant according to the present modification, when the screw head 2b is held between the pair of half bearings 7a and 7b when the spinal implant is assembled, the hollow portion of the second half bearing 7b is retained. Since the projections 28 of the first half bearing 7a are fitted into 29, both are fixed to each other.

  For example, when the hollow part 29 and the protrusion part 28 are not formed in a pair of half bearings as in this configuration, the pair of half bearings in a state where the assembly operator holds the screw head in between is not separated. Thus, it is necessary to insert the pair of half bearings into the housing while pressing both of them, so that the assembly process becomes complicated.

  In this regard, according to the spinal implant according to the present modification, the pair of half bearings 7a and 7b with the screw head 2b held therein are engaged with each other. Thus, there is no need to insert the pair of half bearings into the housing while pressing each other. That is, according to the spinal implant according to this modification, it is possible to provide a spinal implant excellent in assemblability.

  (2) In the above embodiment, as a configuration for engaging the bearing portion 4 and the housing 3, the second groove portion 15 as a concave portion is formed in the housing 3, and the engaging convex portion 25 is formed in the bearing portion 4. However, the configuration is not limited to this, and any configuration may be used as long as the bearing portion 4 and the housing 3 can be engaged with each other.

  (3) In the said embodiment, although the member which comprises each of a pair of half bearing 7 was comprised with the same member, even if each of a pair of half bearing is comprised with a mutually different member, it does not restrict to this. Good.

  (4) In the above embodiment, the radius of curvature of the concave spherical portion 23 formed on the inner peripheral surface of the cylindrical portion 27 is formed to be the same as the radius of the screw head 2b. The radius of curvature of the concave spherical portion 23 may exceed the radius of the screw head 2b or may be less than the radius of the screw head 2b.

  The present invention can be widely applied as a spinal implant for holding a fixation rod for fixing a plurality of spines to each other.

DESCRIPTION OF SYMBOLS 1 Spinal implant 2 Bone screw 2a Screw main-body part 2b Screw head 3 Housing 4 Bearing part (screw head holding | maintenance part)
5 Insert 6 Set screw 7 Half bearing (holding member)
7a First half bearing (holding member)
7b Second half bearing (holding member)
25 Engagement convex part (engagement part)
26 support part 27 cylindrical part L spine R fixation rod (rod)

Claims (6)

A spinal implant for securing the rod to the spine,
The screw main body is formed in a cylindrical shape that holds a screw head of a bone screw that is externally formed with a male screw on the outer surface and is fixed by being screwed to the spine, and is based on the screw head. A screw head holding part having a cylindrical part formed with a support part for supporting the screw head from the lower side when the direction in which the part extends is the lower side,
A housing in which the screw head holding portion in a state of holding the screw head is housed inside, and an engagement portion formed on the screw head holding portion is engaged with the inner peripheral surface side;
The screw head is disposed above the screw head in the housing and receives the pressing force of the rod pressed by a set screw screwed into the housing to press the screw head downward. Inserts to be fixed to,
With
The screw head holding portion has a pair of holding members that sandwich the screw head in a direction perpendicular to the vertical direction, and is inserted into the housing from below the housing with the screw head housed inside. Configured to be possible ,
The engaging portion is an engaging convex portion that engages with a concave portion formed on the inner peripheral surface of the housing,
On the inner peripheral surface of the housing, a groove portion through which the engagement convex portion can pass is formed,
The groove portion is formed so that a groove-shaped first groove portion extending upward from the lower end of the housing and the engagement convex portion passing through the first groove portion can pass therethrough, and extend in a direction intersecting the first groove portion. A spinal implant having a second groove as a recess . The spinal implant of claim 1 , wherein
The spinal implant is characterized in that the pair of holding members have the same size and shape with respect to each other. The spinal implant according to claim 1 or 2 ,
The first holding member that is one of the pair of holding members is formed with a protrusion that fits into a recess formed in the second holding member that is the other of the pair of holding members. Features a spinal implant. The spinal implant according to any one of claims 1 to 3 ,
The insert is formed with an insert-side engaging portion that engages with the inner peripheral surface side of the housing, and the insert-side engaging portion engages with the inner peripheral surface side of the housing. A spinal implant characterized in that circumferential movement relative to the housing is restricted. The spinal implant according to any one of claims 1 to 4 ,
A portion of the cylindrical portion that holds the screw head is formed in a concave spherical shape, and the radius of curvature is the same as the radius of the screw head. , Spinal implants. The spinal implant according to any one of claims 1 to 5 ,
A spinal implant, further comprising the bone screw.

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