RU2520799C1 - Telescopic vertebral prosthesis and method for implantation thereof - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: telescopic vertebral prosthesis comprises an upper cylindrical base with its end face comprising an upper rest pad, a lower cylindrical base with its end face comprising a lower rest pad, a ring coupling and prosthesis height adjusters. The externally threaded upper cylindrical base and the internally threaded ring coupling form a screw pair. The lower cylindrical base with the ring coupling form a movable rotary coupling geared by a circular groove and the ring coupling. The end face of the upper rest pad and the end face of the lower rest pad comprise holders and slots. A side surface of the lower cylindrical base comprises slots. The holders are belted along the external perimeter of the upper and lower rest pads uniformly. An arrow-type holder can have a rectangular- or round-sectioned leg and tip. The tip profile has straight or concave borders. The telescopic prosthesis is implanted from a ventral approach to a lesion using common ventral surgical techniques. The prosthesis is inserted between healthy vertebrae by a relative rotation of the ring coupling to adjust the desired elevation of the prosthesis as shown by the pressure transducer readings. The prosthesis height is adjusted at the moment of pressure being within the range of 150-200 mm Hg. The arrow-type holders are belted along the external perimeter of the upper and lower rest pads.EFFECT: enabling reliable restoration of the primary mechanical stability, forming further secondary metal/osseous unit and avoiding recurrent surgical intervention.11 cl, 5 dwg

Description

The invention relates to medicine, namely to traumatology, orthopedics, vertebrology, including phthisiovertebrology. The invention provides prosthetics for destroyed cervical, thoracic and lumbar vertebral bodies during their traumatic, inflammatory and tumor lesions.

One of the main problems in the implantation of telescopic prostheses of the vertebral bodies when replacing the vertebrae during their destruction, inflammation, and tumor is their migration with the development of instability in the operated segment and the need for reoperation.

Known prosthesis of the vertebral body [US Application No.20120016478, op. 01/19/2012,], including an external cylindrical body, two internal glasses of rectangular cross-section, made with the possibility of mutual axial movement with locking elements of the device. End support platforms of the prosthesis have wedge-shaped retainers.

This design of the prosthesis has the following disadvantages.

During implantation of this product, wedge-shaped anchor-type fixers roughly damage the end plates of adjacent vertebrae, and the closed surface of the prosthesis does not provide the formation of the lateral and end formation of the metal-bone block. The design of the prosthesis does not provide for monitoring the pressure on the cartilage and bone tissue during implantation, which causes a high risk of necrosis in the metal-bone zone and migration of the prosthesis with the need for repeated surgery.

The method of implanting a prosthesis of a vertebral body includes ventral access to the lesion, the installation of a prosthesis between healthy vertebrae. Then, by rotating the coupling, the height of the prosthesis is set based on visual inspection and fixed. Visual control of the height of the prosthesis does not allow to restore the anatomical effort on neighboring vertebrae. If the pressure is high, then this can lead to the development of necrosis in the metal-bone zone, and if the pressure is low, then the prosthesis will migrate.

A vertebral body prosthesis is also known [US Application No. 201110218631, op. September 8, 2011], consisting of their two coaxially moving cylinders and couplings, with retaining elements on the clutch and tenon-shaped clamps on the end support areas of the implant. The fixer is implanted with known ventral surgical methods in the cervical, thoracic and lumbar.

The method of implanting a prosthesis of a vertebral body includes ventral access to the lesion, the installation of a prosthesis between healthy vertebrae. Then, by rotating the coupling, the height of the prosthesis is set based on visual inspection and fixed.

The disadvantages of this design of the prosthesis:

- the absence of longitudinal and end openings on the prosthesis excludes the formation of a durable metal-bone block;

- the design of the prosthesis does not provide for monitoring the pressure on the cartilage and bone tissue with the ends of the prosthesis and, therefore, the risk of developing a zone of necrosis is quite high, and therefore the risk of developing prosthesis migration is high;

- anchor, tenon-shaped retainers of the prosthesis do not provide reliable fixation of the prosthesis in the event of shear loads in the operated segment, and, therefore, predispose the implant to migration;

Visual control of the height of the prosthesis does not allow to restore the anatomical vertical effort on neighboring vertebrae. If the pressure is higher than normal, then this can lead to the development of necrosis in the metal-bone zone, and if the pressure is lower than normal, then the prosthesis will migrate.

Closest to the claimed is a prosthesis of the vertebral body [international application WO No. 2008112923, op. September 16, 2008]. The prosthesis includes an upper cylindrical base, at the end of which an upper supporting platform is made, a lower cylindrical base, at the end of which a lower supporting platform and an annular coupling are made, the upper cylindrical base with an external thread and an annular coupling with an internal thread form a screw pair, and the lower a cylindrical base with an annular groove and an annular coupling with an annular protrusion form a movable connection with meshing. Threaded holes for locking screws are made on the side surface of the annular coupling. On the end surface of the lower and upper bearing pads, tenon-shaped retainers and slots are made, slotted slots are made on the side surface of the lower base.

The method of implanting a prosthesis of the vertebral body includes ventral access to the lesion, installing the prosthesis between healthy vertebrae, adjusting the height of the prosthesis due to the rotation of the annular sleeve based on visual inspection and subsequent fixation of the height of the prosthesis.

The disadvantages of this design of the prosthesis are:

- tenon-shaped retainers of the prosthesis are not able to ensure its reliable fixation;

- the absence of end and side holes eliminates the formation of a metal-bone block;

- the design of the prosthesis does not provide the ability to control the pressure of the ends of the prosthesis on the bone and cartilage tissue during its implantation.

The use of this prosthesis does not guarantee its migration (displacement) and the need for repeated operations.

Visual control of the height of the prosthesis does not allow to restore the anatomical vertical effort on neighboring vertebrae. If the pressure is higher than normal, then this can lead to the development of necrosis in the metal-bone zone, and if the pressure is lower than normal, then the prosthesis will migrate.

The basis of the invention is the task of reducing the risks of early and late instability in the area of the operated segment of the spine and to exclude repeated surgical intervention due to the design features of the prosthesis, which reliably restore the primary mechanical stability during the destruction of one or two vertebrae and subsequently form a strong secondary metal-bone block.

The problem is structurally solved by the fact that in the telescopic prosthesis of the vertebral body containing the upper cylindrical base, at the end of which the upper supporting platform is made, the lower cylindrical base, at the end of which the lower supporting platform, the ring coupling and means for fixing the height of the prosthesis are made, the upper cylindrical base with an external thread and an annular coupling with an internal thread form a screw pair, and the lower cylindrical base with an annular coupling form a movable rotational locking engagement by means of an annular groove and an annular coupling, on the end surface of the upper support platform and the end surface of the lower support platform, latches are installed and slotted holes are made, slotted holes are made on the lateral surface of the lower cylindrical base, according to the invention, latches are installed on the outer perimeter of the upper and lower reference sites evenly in the form of a belt and have an arrow-shaped shape.

In addition, the arrow-shaped latch has a leg and a tip of rectangular cross section, and the profile of the tip has straight faces and concave faces. The arrow-shaped latch may have a leg and a tip of circular cross section.

Means for fixing the height of the prosthesis include threaded holes on the lateral surface of the lower cylindrical base and ridge semicircular notches made along the perimeter of the lower end surface of the annular coupling, and a locking screw. The threaded connection has a trapezoidal profile.

The lateral surface of the upper base is made of evenly spaced and alternating threaded sections and a cylindrical section on which slotted holes are made.

The area of the slit and central holes should be 50-60% of the total surface area of the prosthesis.

When a telescopic prosthesis of the vertebral body is implanted, when the ventral access to the lesion site is previously provided on the basis of the known ventral surgical methods, then the prosthesis is installed between healthy vertebrae, the necessary height of the prosthesis is established by relative rotation of the annular coupling based on visual inspection and the prosthesis height is fixed. The problem is solved by the fact that at least one load cell is injected into the space between the swept retainers and the body of an adjacent healthy vertebra, the height of the prosthesis is selected based on the readings of the load cell. The moment of fixation of the height of the prosthesis is selected at a pressure in the range of 150-200 mm Hg.

The end areas of the cylinder bodies have openings with a total area of more than 50% of the entire end area (for optimal connection of the bone tissue of the prosthesis and the contact vertebra), have lateral longitudinal through holes and a central through hole along the entire axis of the cylinder to fill the prosthesis cavity with crumb bone or hydroxyapatite for osteoinduction , the formation of a metal-bone block (which allows the implant to be implanted in osteopenia and osteoporosis). The lateral surfaces of the cylinder bodies have longitudinal (more than 4 mm) and round through holes (3 mm) for bone growth, and the geometry of the end surfaces of the implant allows you to place a strain gauge between the clamps to control the pressure of the prosthesis on the bone and thereby ensure optimal atraumatic installation of the vertebral prosthesis. In this regard, in patients with prostheses of this design, the development of instability in the operated segment is excluded.

As a result of the use of the prosthesis, primary stability is created in the operated segment, which allows patients to be activated on the first day after surgery. With CT x-ray control, the formation of a full-fledged metal-bone block is observed after 9-12 months (according to the Hounsfield scale in the prosthesis cavity, full-fledged bone tissue is 200-600 units), which allows us to talk about the formation of a reliable block.

The design of the telescopic prosthesis is illustrated by drawings.

Figure 1 presents a General view of a telescopic prosthesis;

figure 2 is a side view with the maximum spaced upper and lower supporting platforms;

figure 3 is a side view with minimally spaced upper and lower supporting platforms;

figure 4 shows the options for the execution of swept latches;

figure 5 shows a General view of a telescopic prosthesis installed between two adjacent intact (healthy) vertebrae.

The telescopic prosthesis contains the lower part 1, the upper part 2 and the annular coupling 3 (Fig.1, 2 and 3). The lower part 1 consists of a lower cylindrical base 4, at the end of which a lower supporting platform 5 is made. The upper part 2 consists of a cylindrical base 6, at the end of which a upper supporting platform 7 is made. The upper supporting platform 7 and the lower supporting platform 5 are a cylindrical cap , on the side surface of which holes 8 are made, and on the end surface - the central hole 9 and slotted holes 10. On the end surface of both the lower supporting platform 5 and the upper supporting platform 7 the belt is filled from the lower and upper arrow-shaped latches 11. The lateral surface of the upper base 6 is made of evenly spaced and alternating sections (Fig. 2) —thread section 12 and cylindrical section 13. An external thread 14 is made on the threaded section 12, and on the cylindrical section 13 there are longitudinal slotted holes 15.

On the lateral surface of the lower cylindrical base 4, alternating rows of threaded holes 16 and slotted holes 17 are made. The threaded holes 16 are for locking screws 18. An annular protrusion 19 is made on the upper end surface of the lower cylindrical base 6, which engages with the annular groove 20 made on the inner surface of the annular coupling 3.

The annular coupling 3 is made in the form of a hollow ring with an internal thread 21. Structurally, the upper part 2 of the prosthesis with an external thread 14 on the upper base 6 and the annular coupling 3 with an internal thread 21 are a screw pair. The outer surface of the annular coupling 3 has a cylindrical segment 22 and a conical segment 23. The end surface of the cylindrical segment 22 of the annular coupling 3 is comb-shaped, with semicircular recesses 24.

The total area of the holes and slotted slots in the body of the prosthesis should be at least 50% of the side and end surfaces of the lower part 1, upper parts 2 and the annular coupling 3.

The lower and upper latches 11 are arrow-shaped (Fig. 4 a, b, c, d, e, f). The locking elements 11 have a leg 25 and a tip 26 with a tip 27. The section of the clamps can be square or rectangular (Fig.5 a, c, e) or round (Fig.5 c, d, f). The profile of the side face of the tip 26 can be made flat 28 or concave 29. In addition, the tip can have two points (Fig. 5 e, f).

The prosthesis is configured to install, during the operation, a pressure sensor 30 on the end surface of the upper supporting platform 7, between the upper arrow-shaped latches 11. The sensor 30 is designed to measure forces between the upper healthy vertebra 31 and the prosthesis and, respectively, between the lower healthy vertebra 32 and the prosthesis.

The prosthesis may be made of any biocompatible material or combinations of any biocompatible materials known in the art, including: stainless steel, titanium, titanium alloys, ceramics, polymers, polytetrafluoroethylene ("PTFE"). Preferably, the prosthesis is made of polyether ether ketone ("PEEK").

Given the features of operations, the prosthesis can be made radiopaque so that the establishment (placement) and location of the prosthesis can be visualized. In addition, one or more coatings can be applied to reduce friction and wear. The choice of prosthesis material and its coating is determined by the necessary strength and durability.

When the vertebra is destroyed, the lesion site is examined using an X-ray machine. The radiograph with a focus of 1: 1 measures the height of adjacent vertebrae and prepares an appropriate prosthesis. Currently, three standard sizes of prostheses with a diameter of 13, 22 and 26 mm are made with anatomical dimensions of height, which overlaps the possible height of the vertebrae of an adult, by adjusting the height of the prosthesis. The size determined by the outer diameter determines its specific application: the cervical vertebra is 13 mm in size, the thoracic vertebra is 18 mm, and the lumbar vertebra is 22 mm.

Then complete or partial removal of the damaged cervical, thoracic or lumbar vertebra is carried out and a telescopic prosthesis is inserted into the intervertebral space created by the removal of parts or the entire vertebral organ between two intact (healthy) vertebrae. Intervertebral implantation should restore the spine as much as possible to the natural, previously existing position for the patient. Those. it is necessary to restore the original height of the intervertebral disc and thus the initial distance between two adjacent vertebral organs, and the degree of their mutual pressure, which is different at different levels of the spine.

So, for example, when an implant is implanted in the cervical spine, a patient under general anesthesia in the supine position is given ventral access to the broken vertebra. An anterior longitudinal ligament is dissected H-shaped, and under the control of the image intensifier, a broken (either spondylitic or tumor-affected) vertebra with adjacent discs is removed. A strain gauge 30 is installed in the space between the upper retainers 11 of the prosthesis.

Then the prosthesis holder is installed in the intervertebral space using x-ray control in two projections, pre-filling the prosthesis with bone crumbs, and in cases with a tumor or inflammation of the vertebra, the prosthesis is filled with hydroxyapatite. When this strain gauge 30 is located between the end surface of the upper supporting platform 7 and the upper healthy vertebra 31 (figure 5).

With a special key, rotate the annular sleeve 3 and thereby extend the prosthesis to touch the end surfaces of the lower and upper supporting sites 5 and 7 with the bodies of adjacent healthy vertebrae 31 and 32, while the clamps 11 are inserted into the body of adjacent healthy vertebrae 31 and 32. Control efforts on adjacent healthy vertebrae 31 and 32 are carried out on a special monitor. When the required pressure is reached, the rotation of the annular coupling 3 is stopped and the prosthesis height is fixed with the locking screw 18. The locking screw 18 is screwed into the threaded hole 16 of the lower cylindrical base 4, which, with its tail, enters the semicircular recess 24 and blocks the possibility of rotation of the annular coupling 3. Then the load cell 30 is removed and the wound is sutured in layers.

The moment of fixing the height of the prosthesis is determined by the pressure of the end surfaces of the supporting platforms of the prosthesis 5 and 7 on adjacent healthy vertebrae 31 and 32, which is selected within the range of 150-200 mm Hg With greater pressure, bone cells die in the implantation zone of the prosthesis and instability of the prosthesis develops with its subsequent displacement and the resumption of pain. At lower pressure, the necessary implant implantation strength is not ensured, which will also lead to instability of the prosthesis and its displacement.

High primary stabilizing properties of the prosthesis allow patients to be activated on the first day after surgery without external splinting.

The essence of the method is illustrated by a clinical example. Patient T., 34 years old, was admitted to the hospital with a diagnosis of comminuted fracture of the C5 vertebra with partial compression of the spinal cord. Neurological deficit: mild tetraparesis. Orthopedic: pain syndrome is expressed, a clinic of severe instability in the cervical spine. After an express examination, an operation was performed - resection of the C 5 vertebra and its replacement with a prosthesis of the vertebral body. Activated on the first day, discharged on the 14th day with a complete regression of disorders.

Claims (11)

1. The telescopic prosthesis of the vertebral body contains an upper cylindrical base, at the end of which an upper supporting platform is made, a lower cylindrical base, at the end of which a lower supporting platform, an annular coupling and means for fixing the prosthesis height are made, the upper cylindrical base with external thread and an annular coupling with they form a screw pair with internal thread, and the lower cylindrical base with an annular coupling form a movable rotational connection with engagement due to the annular groove and ring gates, on the end surface of the upper bearing pad and the end surface of the lower bearing pad, latches are installed and slotted holes are made, slotted holes are made on the lateral surface of the lower cylindrical base, characterized in that the latches are mounted uniformly in the form of a belt along the outer perimeter of the upper and lower supporting platforms and have an arrow-shaped shape. 2. The prosthesis according to claim 1, characterized in that the arrow-shaped retainer has a leg and a tip of rectangular cross section. 3. The prosthesis according to claim 2, characterized in that the tip profile has straight faces. 4. The prosthesis according to claim 2, characterized in that the tip profile has concave faces. 5. The prosthesis according to claim 1, characterized in that the arrow-shaped retainer has a leg and a tip of circular cross section. 6. The prosthesis according to claim 1, characterized in that the means for fixing the height of the prosthesis include threaded holes on the side surface of the lower cylindrical base and ridge semicircular recesses made along the perimeter of the lower end surface of the annular coupling, and a locking screw. 7. The prosthesis according to claim 1, characterized in that the threaded connection has a trapezoidal profile. 8. The prosthesis according to claim 1, characterized in that the side surface of the upper base is made of evenly spaced and alternating threaded sections and a cylindrical section on which slotted holes are made. 9. The prosthesis according to claim 1, characterized in that the area of the slit and central holes is 50-60% of the total surface area of the prosthesis. 10. The method of implanting a telescopic prosthesis of the vertebral body, which consists in preliminarily providing ventral access to the lesion based on known ventral surgical methods, then installing the prosthesis between healthy vertebrae, setting the required height of the prosthesis by rotating the ring sleeve based on visual inspection and fixing the height prosthesis, characterized in that at least one load cell is inserted into the space between the swept retainers and the body of the adjacent of the pre-vertebral vertebra, the height is selected based on the readings of the strain gauge. 11. The method according to claim 10, characterized in that the moment of fixing the height of the prosthesis is selected at a pressure in the range of 150-200 mm RT. Art.

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