JP7221661B2 - Single open cervical laminoplasty bone fixation device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bone fixation instrument for holding a vertebral arch in a wide open position for use in single-sided (open door type) cervical laminoplasty.

As shown in Fig. 1, the cervical spine is surrounded by the left and right vertebral arches A on the dorsal side D, the vertebral bodies B on the ventral side V, and the left and right lateral masses LM laterally. are doing. When spinal canal stenosis occurs due to bone deformation of the cervical vertebrae, posterior longitudinal ligament ossification, intervertebral disc herniation, etc., various symptoms due to compression of the spinal cord (myelopathy) may occur. Lamineoplasty is commonly performed for myelopathy with extensive stenosis of the spinal canal. Lamineoplasty is an operation to expand the spinal canal by deforming the vertebral arch. As shown in Fig. 2, this is a surgical procedure in which one of the left and right lateral portions of the vertebral arch A is cut, a groove is made in the other lateral portion, and the vertebral arch is opened as a hinge H. In order to maintain dilatation and fuse the hinge with the bones, an instrument is often placed between the cut ends R of the vertebral arch. A ceramic instrument is fastened to the bone with a thread, and a metal plate 0 as in Reference 1 is screwed to the bone.

When creating the hinge H, a groove is dug by shaving the bone so as not to cut the vertebral arch A, and when the vertebral arch is opened, the remaining bone at the bottom of the groove is bent like a young bamboo. Although bones have elasticity, they are harder than young bamboo, so a certain amount of force is required to bend them. When installing and fixing the plate 0 for maintaining dilatation, the vertebral arch is dilated, the plate 0 is installed in a narrow space, a bone hole for the fixing screw hole is prepared, and the screw is inserted. Bone hole preparation is a task that requires a lot of force to drill through the bone cortex. In addition, it is necessary to hold the plate 0 firmly so as not to lose sight of the screw holes and to resist the turning force when screwing. It is difficult to work in a narrow space because the plate holding device, the hole punching device, and the plate itself interfere with each other. It is difficult for a single operator to perform narrow and delicate work that requires strength at the same time, which requires skill. In addition, the part where the fixing screw 01 is inserted is set on the outside so as not to interfere with the stick part of the plate 0, and it is necessary to expose the bone by exfoliating the muscle extensively to the outside. In order to preserve the muscle, it is desirable to minimize the detachment of the muscle from the bone.

JP 2010-142657 JP 2014-529472

The purpose is to facilitate the installation of the lamina dilatation holding device used in single-sided laminoplasty, to enable the operator to perform the operation alone, and to minimize the extent of muscle detachment.

The present invention consists of two parts, a metal outer mass fixation screw and a pedicle support bracket.
The screw head of the outer mass fixing screw has a screw head with a plus-shaped groove where two grooves intersect at 90 degrees, or a groove with three grooves intersecting at 60 degrees. The outer edge of the groove is closed.
The flat plate of the pedicle support bracket is bent, and the dorsal side is the lamina contact part, and the ventral side is the base. There are threading holes and sharp protrusions at the vertebral arch contact area.
The groove for the driver is deep and serves not only for connection with the driver but also for the base of the pedicle support metal fitting. The inclination of the bow support bracket is restricted.

In the surgical procedure, after cutting the vertebral arch and creating a hinge as described above, a bone hole is made slightly outside the lamina cut with a drill or awl, and the outer mass fixation screw is inserted there with a screwdriver. Twist it to fix it in the outer mass. At the end of turning the driver at that time, the long side of one of the grooves for the driver should be parallel to the craniocaudal axis of the cervical vertebrae. Pass the thread through the threading hole of the vertebral arch support fitting. Hook a tool such as a hook on the cut end of the lamina to open the vertebral arch, apply the lamina contact part of the lamina support fitting to the ventral side of the cut end of the lamina, and then press the base of the lamina support fitting. Insert the ventral end into the driver groove of the lateral mass fixation screw. Both ends of the thread are passed through the cranial and caudal sides of the vertebral arch with curved needles, respectively, and then the thread is tied on the dorsal side of the vertebral arch.

The groove for the driver is deep, and the vertebral arch support metal fitting inserted there hits the inner wall of the groove for the driver and does not fall down easily. In addition, since the opened vertebral arch tends to return to its original state due to its elasticity, it acts to press the pedicle support fitting against the lateral mass fixation screw, making it difficult for the pedicle support fitting to come off from the lateral mass fixation screw. In addition, the sharp protrusion of the pedicle support metal fitting sticks into the vertebral arch ventral side, and the pedicle and pedicle support metal fittings are prevented from slipping by tightening the thread passed through the threading hole.

In the present invention, by dividing the part fixed to the lateral mass and the part that keeps the vertebral arch open, it is not necessary to simultaneously perform the work of keeping the vertebral arch open and the work of fixing it to the lateral mass. becomes easier. Furthermore, the instrument does not interfere with the work of drilling a bone hole, making work easier even in a narrow space. With the conventional plate, when the fixation screw is turned, the rotational force is transmitted to the plate and the plate may be displaced from the vertebral arch, but this problem is eliminated.

In conventional instruments, the fixing screw was installed sufficiently outside the tsutsukai rod so as not to interfere with the part that plays the role of the tsutsukai rod (the part corresponding to the base in this invention). Since the screw is directly under the part, muscle detachment to the outside is improved in a small area.

Cross-sectional anatomy of the cervical spine. Cross-sectional view of unilateral open laminoplasty using existing metal plates. Fig. 2 is an oblique view of the lateral mass fixation screw of the present invention; FIG. 2 is a dorsal side view of the lateral mass fixation screw of the present invention. Fig. 2 is an oblique view of form 1 of the lamina support fitting of the present invention; Fig. 2 is an oblique view of form 2 of the lamina support bracket of the present invention; Fig. 3 is an oblique view of configuration 3 of the lamina support bracket of the present invention; Fig. 4 is an oblique view of configuration 4 of the lamina support bracket of the present invention; First step of the surgical procedure of the present invention. Second step of the surgical procedure of the present invention. Three stages of the surgical procedure of the present invention. Final stage of the surgical procedure of the present invention. FIG. 2 is a cross-sectional view of the ventral end of the pedicle support bracket base of the present invention and the groove for the driver; Oblique view of the hexagonal prism type of the subtype of the present invention.

Embodiments of the present invention will be described with reference to FIGS. It consists of an outer mass fixation screw 1 shown in Fig. 3 and a vertebral arch support bracket 2 shown in Figs. 5 to 8, both of which are made of titanium. The driver groove 102 of the screw head 101 of the outer mass fixing screw 1 is a plus shape in which two grooves intersect at 90° when viewed from the back side (upper side in FIG. 3), and the depth of the groove is the width of the groove ( : length of the short side of the groove), preferably with a depth of about 3 mm. The outer edge of the groove is closed. There is a screw portion 103 on the ventral side (lower side in FIG. 3) of the screw head 101 of the outer mass fixing screw 1 .

The shape of the driver groove 102 of the outer mass fixing screw 1 has at least one straight groove when viewed from the dorsal side. A driver groove (Fig. 4b) is also conceivable. It is conceivable that the outer edge of the groove for the driver is not closed. The tip of the driver corresponds to the shape of the groove.

The vertebral arch support fitting 2 shown in FIG. 8 has a bent flat plate, and is composed of a vertebral arch contact portion 201 and a base portion 205 bordering on the bent portion. A sharp protrusion 202 is located on the back surface (upper side in FIG. 8) of the vertebral arch contact portion 201, and a threading hole 203 is provided in the vertebral arch contact portion. Since the ventral end (lower in FIG. 8) of the base 205 of the pedicle support bracket 2 is smaller than the driver groove 102 of the lateral mass fixation screw 1, the base 205 can be inserted into the driver groove 102.
A mark 206 corresponding to the depth of the driver groove 102 is provided on the ventral side of the base 205 .

The vertebral arch contact portion 201 of the vertebral arch support metal fitting 2 may have neither the sharp protrusion 202 nor the threading hole 203 as shown in FIGS.

13 is a sectional view parallel to the short side of the driver groove when the ventral end of the base 205 of the vertebral arch support metal fitting 2 is inserted into the driver groove 102 of the screw head 101. FIG. As shown in FIG. 13a, both the cross-sectional shape of the groove inner cavity of the driver groove 102 of the outer lump screw 1 and the cross-sectional shape of the ventral side end of the base 205 of the vertebral arch support metal fitting 2 are square prisms. , the groove width (: short side length of the groove) of the screw head 101 for the driver groove 102 is smaller at the deeper part, the inner surface of the groove is inclined, and the ventral end of the base 205 of the vertebral arch support metal fitting 2 The portion is tapered and has an inclined surface parallel to the inner surface of the driver groove 102, so that the ventral end of the base 205 of the vertebral arch support fitting 2 can be easily inserted into the driver groove 102. It is also possible to consider a form in which both are in close contact with each other.

In the surgical procedure, after making a cut R and a hinge H in the vertebral arch A (Fig. 9), a bone hole that will be a screw hole is made slightly outside the lamina cut R with a drill or awl, and the outer mass is made there. Fix the fixing screw 1 to the outer mass LM by turning it with a screwdriver (Fig. 10). The long side of one of the driver grooves 102 is made parallel to the head-caudal axis of the cervical vertebrae (perpendicular to the drawing in FIG. 10) when the driver is finally turned. A thread 207 is threaded through the threading hole 203 of the vertebral arch support fitting 2. A tool such as a hook is hooked to the cut end R of the lamina to open the lamina A, and the lamina contact portion of the lamina support fitting 2 is placed on the ventral side of the cut end of the lamina A (lower in FIG. 11). 201 (FIG. 11), insert the ventral end of the base 205 of the pedicle support fitting 2 into the driver groove 102 of the lateral mass fixation screw 1 . Both ends of the thread 207 are passed through the cranial and caudal sides of the vertebral arch A with curved needles, respectively, and then the thread 207 is tied on the dorsal side of the vertebral arch (upper side in FIG. 12) (FIG. 12). If it is still unstable, a cyanoacrylate adhesive is poured into the empty groove of the driver groove 102 after inserting the base 205 of the vertebral arch support metal fitting 2 to enhance fixation.

As shown in Fig. 14, the vertebral arch support bracket 2' has a bent hexagonal prism shape, and a subtype in which the bore of the driver groove 102' of the lateral mass fixation screw 1' has a hexagonal prism shape is also conceivable.

D Dorsal side V Ventral side A Vertebral arch B Vertebral body LM Lateral mass C Spinal cord 1 Lateral mass fixing screw 101 Screw head 102 Driver groove 103 Screw part 2 Vertebral arch support fitting 201 Vertebral arch contact part 202 Sharp protrusion 203 Threading hole 205 Base 206 Mark 207 Thread

Claims (5)

A bone fixation device for holding a vertebral arch in a wide open position in single-sided cervical laminoplasty,
Consists of separable members into the lateral mass fixation screw and the vertebral arch support bracket,
The outer mass fixing screw has a screw part fixed to the outer mass, the screw head has a screwdriver groove,
The vertebral arch support bracket is bent to form a base with the lamina contact part, the lamina contact part is applied near the cut end of the open vertebral arch, and the base is a support that maintains the opening between the cut ends of the lamina. A bone that acts as a rod, the ventral end of the base of the pedicle support fitting can be inserted into the groove for the driver, and the inserted pedicle support fitting base is limited in inclination within the groove for the driver. Fixing device. The vertebral arch support fitting has a bent flat plate shape, and has a sharp projection on the dorsal side of the vertebral arch contact portion, or has a hole or ring for threading in the vertebral arch contact portion, or has a sharp projection and a threading hole. There are both holes or rings of
2. The bone fixation device according to claim 1, wherein a mark corresponding to the depth of the driver groove is provided on the ventral side of the base of said lamina support fitting. The driver groove of the outer mass fixing screw has at least one straight groove when viewed from the dorsal side. The bone fixation device according to claim 1, characterized in that there is a . The groove width of the driver groove of the outer lump fixing screw is smaller at a deeper portion, and the inner surface of the groove is inclined,
The thickness of the ventral side end of the base of the vertebral arch support metal fitting decreases toward the ventral side and forms an inclined surface parallel to the inner surface of the groove for the driver,
2. The bone fixation device according to claim 1 , wherein when the ventral side of the base of the pedicle support fitting is inserted into the groove for the driver, the two face each other and the inclination of the pedicle support fitting is restricted. . 2. The bone fixation device according to claim 1, wherein the shape of the inner lumen of the driver groove of said outer mass fixation screw and the shape of the base of said vertebral arch support fitting are polygonal prism shapes such as hexagonal prisms.

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