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WO2015095965A1 - Dispositif d'ancrage - Google Patents

Dispositif d'ancrage Download PDF

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Publication number
WO2015095965A1
WO2015095965A1 PCT/CA2014/051254 CA2014051254W WO2015095965A1 WO 2015095965 A1 WO2015095965 A1 WO 2015095965A1 CA 2014051254 W CA2014051254 W CA 2014051254W WO 2015095965 A1 WO2015095965 A1 WO 2015095965A1
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WIPO (PCT)
Prior art keywords
tubular body
helical
anchor device
angle
screw
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CA2014/051254
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English (en)
Inventor
Parham RASOULINEJAD
Jacob REEVES
Stewart MCLACHLIN
Fawaz SIDDIQI
Christopher Bailey
Kevin Gurr
Cynthia DUNNING
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Western Ontario
Original Assignee
University of Western Ontario
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Filing date
Publication date
Application filed by University of Western Ontario filed Critical University of Western Ontario
Publication of WO2015095965A1 publication Critical patent/WO2015095965A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
    • A61B17/86—Pins or screws or threaded wires; nuts therefor
    • A61B17/869—Pins or screws or threaded wires; nuts therefor characterised by an open form, e.g. wire helix
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
    • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
    • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
    • A61B17/70—Spinal positioners or stabilisers, e.g. stabilisers comprising fluid filler in an implant
    • A61B17/7001—Screws or hooks combined with longitudinal elements which do not contact vertebrae
    • A61B17/7032—Screws or hooks with U-shaped head or back through which longitudinal rods pass

Definitions

  • the present invention relates to anchoring devices that can be installed in an access hole in a wall, and more particularly anchoring devices that are expandable to abut a surface forming or surrounding the access hole.
  • pedicle screws and their use by spinal surgeons has dramatically improved the surgical care of patients with spinal disease. Improved clinical outcomes have been demonstrated in a variety of spinal disorders including: scoliosis, kyphosis, spinal fractures, spondylolisthesis, degenerative lumbar disease, neoplasms, autoimmune disease and more.
  • spinal disorders including: scoliosis, kyphosis, spinal fractures, spondylolisthesis, degenerative lumbar disease, neoplasms, autoimmune disease and more.
  • the use of pedicle screws has resulted in better achievement and maintenance of alignment correction, along with a reduction in the need for brace utilization.
  • the pedicle screw construct has allowed surgeons to fuse fewer segments and better correct post-traumatic kyphotic deformities with greater success.
  • the fusion rates have increase substantially.
  • the surgeon's ability to reduce and maintain the deformity has also improved, increasing the overall rate of surgical success and acceptable outcome with a corresponding reduction in overall risk.
  • the use of pedicle screw fixation has allowed for percutaneous and minimally invasive approaches to be developed for the treatment of spondylolisthesis and other spinal deformities.
  • the use of short constructs with only a few levels instrumented has allowed for safe radical resection of primary spinal tumors to be performed with improved outcomes.
  • pedicle screw represents state of the art treatment in spinal disease, it has limitations. One of these is the inability of the current screw designs to provide sufficient fixation in osteoporotic bone, or with revision surgery, as well as insufficient stability in badly traumatized patients.
  • the screw-bone interface is an element that determines the strength of a surgical construct. This screw-bone interface is compromised substantially in osteoporosis. Beyond bone quality, other factors have been shown to effect screw bone fixation including: screw diameter pedicle match (i.e., ability of screw to fill the pedicle), screw length, thread pitch, thread type, shape of the minor diameter, shape of major diameter, angle of screw insertion, use of cross-linking, insertion torque, pretapping the pedicle, bilateralism of fixation, augmentation with bone cement, use of hollow screws and more.
  • bone cement such as methyl methacrylate, calcium triglyceride, or polypropylene glycol fumarate.
  • an anchor device for use in orthopedic surgery in an access hole formed in a bone, the anchor device comprising: an elongate tubular body defining opposing first and second ends and a longitudinal central axis extending therebetween; the elongate tubular body bound by an exterior surface and an interior surface; the interior surface defining a lumen extending between the opposing first and second ends; a flanged opening at the first end communicative with the lumen; a helical thread extending radially outward from the exterior surface of the tubular body; a helical slit within the tubular body in reverse orientation to the helical thread, the helical slit extending from the exterior surface to the interior surface and communicative with the lumen, the helical slit directing circumferential expansion of the tubular body when the tubular body is longitudinally compressed.
  • an anchor device comprising: an elongate tubular body defining opposing first and second ends and a longitudinal central axis extending therebetween; the elongate tubular body bound by an exterior surface and an interior surface; the interior surface defining a lumen extending between the opposing first and second ends; an opening at the first end communicative with the lumen; a helical slit within the tubular body, the helical slit extending from the exterior surface to the interior surface and communicative with the lumen, the helical slit directing circumferential expansion of the tubular body when the tubular body is longitudinally compressed.
  • Figure 1 shows a perspective view of an anchor device
  • Figure 2 shows several side views (A) a first plan side view, (B) a second plan side view, and (C) a cross-sectional side view taken along line 2C-2C, of the anchor device shown in Figure 1 ;
  • Figure 3 shows a magnified view of circle 3 from Figure 2C;
  • Figure 4 shows a magnified view of circle 4 from Figure 2C;
  • Figure 5A-D shows a schematic use of the anchor device shown in Figure 1 in conjunction with a screw actuator
  • Figure 6 shows various X-ray views of an experimental demonstration of an implementation of the anchor device shown in Figure 1 adapted for installation in pedicle bone and circumferentially expanded using a screw actuator;
  • Figure 7 shows a graph plotting energy required for removal from bone of the anchor device shown in Figure 1 and a comparable removal of a standard screw;
  • Figure 8 shows a summary of results from a larger sample size using the same experimental set up as in Figure 7.
  • Figure 9 shows a representation of some parameters that may effect radial expansion of the anchor device shown in Figure 1.
  • Figures 1 to 4 show various views of an anchor device 10, while Figure 5 schematically shows a use of the anchor device 10.
  • the anchor device 10 is designed for installation in an access hole formed in a bone during a surgical procedure.
  • the anchor device 10 comprises an elongate tubular body 12.
  • the elongate tubular body is typically a hollow cylinder having opposing first 14 and second 15 ends with a longitudinal central axis 17 extending from the first end 14 to the second end 15.
  • the elongate tubular body comprises a sidewall 19 bound by an exterior surface 20 and a concentric interior surface 21.
  • the thickness of the sidewall 19 defined by the distance between the exterior surface 20 and the concentric interior surface 21 is substantially uniform for a majority of the axial length of the sidewall 19.
  • the interior surface 21 defines an interior channel or lumen 24 of the elongate tubular body extending from the first end 14 to the second end 15.
  • the interior lumen 24 is typically co-axial with the elongate tubular body sidewall 19.
  • An opening 26 communicative with the interior lumen 24 is formed at the first end 14.
  • the opening 26 is sized to receive a portion of an actuator, for example an actuator shaft.
  • an opening communicative with lumen 24 may also be formed at the second end 15. Generally, for convenience an opening is provided at the second end.
  • a helical thread 27 is formed in the interior surface 21 at or proximal to the second end 15.
  • the helical thread 27 extends radially inward.
  • the helical thread 27 functions to engage a threaded portion 86 of a screw actuator 80 providing an adjustable contact point for the screw actuator 80 proximal to the second end of the tubular body 12.
  • a progressive compressive load can be applied to the tubular body 12 between the two contact points by clockwise rotation of the screw actuator 80.
  • An opening at the second end 15 allows for the helical thread 27 to be shorter and or located in greater proximity to the second end 15 compared to a similar construct with a closed second end.
  • the opening 26 at the first end 14 is contoured by flange 28 extending radially outward from the sidewall 19 at or proximal to the first end 14.
  • the flange 28 functions to abut an exterior wall surface surrounding an access hole restricting motion of the anchor device through the access hole.
  • the flange 28 is shaped as a bowl bound by an interior straight edged polygonal surface 30 and an exterior convex surface 31 joined at a peripheral rim 32 with opening 26 located in a central portion of the flange 28. Opening 26 is beveled or tapered radially outward as it extends axially towards the interior surface 30 of flange 28.
  • the radial cross-section diameter of opening 26 is at its widest at the interior surface 30 of flange 28 with the diameter narrowing as opening 26 tapers along an axial length in between the interior surface 30 of flange 28 and the first end 14 of the elongate tubular body 12.
  • the tapering of opening 26 functions to mate with a corresponding tapering of the head 84 of screw actuator 80 used to apply a compressive load to the anchor device 10 to effect radial or circumferential expansion of the tubular body 12.
  • Arcuate sidewalls 34 extend axially outward from the peripheral rim 32 of the flange 28 to form an open cylindrical head.
  • the open cylindrical head is typically communicative and co-axial with the lumen 24.
  • the two arcuate sidewalls 34 forming the open cylindrical head are separated by gaps that run the axial length of the arcuate sidewalls 34.
  • the arcuate sidewall 34 may be a continuous cylindrical sidewall.
  • the interior surface of the arcuate sidewalls 34 are threaded 36 to engage a threaded connector during a surgical procedure.
  • the open cylindrical head structure is often termed a tulip head.
  • a helical thread 40 extends radially outward from the exterior surface 20 of the tubular body 12 and a helical slit or groove 50 is formed in the sidewall 19 of the tubular body 12.
  • the direction of the helical turns of the helical slit 50 is reverse to the direction of the helical thread 40 to reduce the risk of the tubular body 12 unwinding along the helical slit 50 during rotation of the anchor device 10 through an access hole with penetration of the helical thread 40 in the cylindrical sidewall of the access hole.
  • the helical slit 50 is bordered by first 52 and second 53 opposing continuous helical edges cutout of the sidewall 19 of the tubular body 12.
  • the first 52 and second 53 opposing continuous edges extend from the exterior surface 20 of the sidewall 19 to the interior surface 21.
  • the helical slit 50 is communicative with the lumen 24, extending through the sidewall 19 of the tubular body 12 from the exterior surface 20 to the interior surface 21.
  • the distance between first helical edge 52 and second helical edge 53 will typically be substantially uniform to achieve a substantially uniform width of the helical slit 50 along its entire length.
  • first 52 and second 53 helical edges may be differentiated to benefit a helical slit 50 directed radial expansion of the tubular body 12 upon application of a compressive load to the tubular body 12.
  • the angles of the first and second helical edges may be defined with reference to the central axis of the tubular body or with reference to a tangent to the interior surface 21 of the tubular body 12. Also for reference, 0 degrees is towards the first end 14 and parallel to the central axis or tangent of the interior surface 21, 180 degrees is towards the second end 15 and parallel to the central axis or tangent of the interior surface 21, and 90 degrees is perpendicular to the central axis or tangent of the interior surface 21.
  • the first 52 and second 53 helical edges When the first 52 and second 53 helical edges are pushed together due to axial compression of the tubular body, identically angled edges provide the greatest contact surface area, while increasing the difference between the angles of the edges correlates to a decrease in the contact surface area. Testing described herein supports an observation that increasing an angle differential, and thereby presumably decreasing the contact surface area between the edges, decreases the compressive load needed to achieve radial expansion. Furthermore, without wishing to be bound by theory, when the angles are different, for example with a pair of different acute angles, the lesser angled first edge 52 may provide a ramp for sliding of the greater angled second edge 53 allowing for a more consistent stacking of the greater angled second edge 53 over (or outward) from the lesser angled first edge 52 upon axial compression of the tubular body.
  • a greater angled second edge may provide a ramp for sliding of a lesser angled first edge allowing for a more consistent stacking of the lesser angled first edge over (or outward) from the greater angled second edge upon axial compression of the tubular body.
  • the first helical edge 52 has an angle of 40 degrees while the second helical edge 53 has an angle of 80 degrees, resulting in an angle differential of 40 degrees.
  • the differential between the angles of the first and second helical edges will be at least 10 degrees.
  • the angles of both the first and second helical edges may be less than about 90 degrees.
  • the angles of both the first and second helical edges may be greater than about 90 degrees. Should both edges be angled less than 90 degrees, the second helical edge 53 will typically rise over the first helical edge 52. Should both edges be angled greater than 90 degrees, the first helical edge 52 will typically rise over the second helical edge 53. If both edges are equal to 90 degrees, a predictable stacking may not occur.
  • first edge forms an acute angle and the second edge an obtuse angle
  • either edge may rise over the other.
  • combinations of differentially angled first and second edges may be selected to predetermine whether initial edge-to-edge contact will be made between the outer (outer surface 20) corner or inner (inner surface 21) corner of the edges during axial compression of the tubular body 12.
  • first helical edge 52 having an angle of 40 degrees and the second helical edge 53 having an angle of 80 degrees as shown in Figure 4 would be expected to make initial edge-to-edge contact at or near the inner corner of the edges.
  • first helical edge 52 will have the lesser or equal angle, and both angles will be less than 90 degrees to promote stacking from the second end 15 (distal end) of the screw to the first end 14 (proximal end).
  • Many other angled first and second edge combinations may be useful including various combinations of acute angles, obtuse angles or both acute and obtuse angles. However a combination of both angles being 90 degrees, or a combination comprising angles approaching zero degrees or approaching 180 degrees will typically be avoided.
  • most examples of first and second edge angle combinations will typically have at least one angle that is non-perpendicular to the central axis or interior surface 21, and having both angles non-parallel to the central axis or interior surface 21. Suitability of specific first and second edge angle combinations can readily be determined and tested, for example by computer modeling and/or by machining test devices and monitoring stacking during application of a compressive load.
  • FIG. 5 A A schematic use of the anchor device 10 is shown in Figure 5.
  • the anchor device may be threaded into an access hole formed in a bone until flange 28 abuts the exterior surface of the bone.
  • a screw actuator 80 is then inserted into the lumen 24 of the tubular body 12 (Figure 5B).
  • the screw actuator 80 comprises an elongate cylindrical shaft 82 sized to be rotatably received within the lumen 24 of the tubular body 12.
  • a head 84 formed at a first end of shaft 82 is sized to be larger than the opening 26 at the first end 14 of the tubular body.
  • a threaded portion 86 formed at a second end of the shaft 82 is sized to engage the helical thread formed in the interior surface at the second end of the tubular body.
  • the expanded anchor device is stronger due to a plurality of helical turns stacking upon each as compared to a single anchoring surface such as would be the case for a wing or flange extending from the tubular body.
  • the circumferential nature of the expansion allows the stress from any pull-out load applied to the anchor device when in use to be distributed more uniformly in and/or around the access hole as compared to discrete anchoring surfaces such as wings.
  • the close and uniform stacking of the helical turns may prevent or delay bone ingrowth allowing for removal of the anchor device at longer time periods after installation compared to anchor devices that provide spaces for bone ingrowth in their anchoring structures.
  • the anchor device may be configured to be reversibly installed and may be removed after a period of time (on the scale of weeks, perhaps even months) has lapsed post-insertion.
  • Removal of an installed anchor device may be useful in many scenarios, including for example: 1) infection - in the event of a deep infection, hardware of any kind is susceptible to bacterial biofilm formation that may not be treatable by antibiotic, and thus the hardware may need to be removed completely to allow for treatment of the infection; 2) if a screw is misplaced and is causing compression of nerve roots/spinal cord or other vital structures, it may need to be removed; or 3) in case of revision surgery, previous screws may need to be removed to allow for surgical access.
  • the anchor device is interchangeably termed a screw, a pedicle screw, a helical pedicle screw, an expandable screw, expandable helix screw or a helical screw shell.
  • the following experimental example is for illustration purposes only and is not intended to be a limiting description.
  • the pedicle screw can be divided into 4 basic components: head, core, thread and tip. Alterations to any of these components may change the mechanical properties of the screw, as well as its interface with bone. Screws are commonly utilized in surgical procedures involving bone, and different screw attributes and designs have been well studied.
  • the head of spinal pedicle screws is often referred to as a 'tulip'.
  • a screw head functions to resist the translational force created by the rotation of the screw once the screw is fully tightened with its head abutting against the surface into which the screw is placed.
  • the head can play two roles: resist the translation force and act as the anchor point for fixation to a rod which connects the other screws along the screw-rod construct. This mechanism has been well studied and well designed and is very rarely the point of failure.
  • the core of the screw i.e., minor diameter
  • the screw's strength is proportional to the cube of the minor diameter.
  • the fracture strength of the screw increases exponentially as the minor diameter is increased. It would then seem intuitive that the screw with the largest minor diameter that is anatomically possible would be the best treatment option; however, this is not the case.
  • One issue with a large core (minor) diameter is sacrifice of the thread depth, a factor discussed in detail below.
  • increased minor diameter results in a stiffer screw and subsequently a stiffer surgical construct, which has been associated with stress shielding of the bone.
  • the screw thread design can effect pull-out strength and multiple aspects of the thread can be modified.
  • the 3 most critical design elements are thread depth, pitch, and type.
  • Thread depth is defined as the difference between the minor and major diameters, where the latter is the largest diameter of screw measured to the tips of the threads. Generally speaking, larger thread depth results in better bone purchase and stronger screw pull-out in soft cancellous bone such as the bone in the vertebral body. However, increasing thread depth results in sacrifice of minor diameter, and thus fracture strength.
  • Thread pitch when considered in metric measurement, is defined as the distance between two adjacent threads. Alternatively, the pitch as defined as the number of threads per inch or TPI in the standard measurement system.
  • thread type refers to the shape of the thread, of which there are nearly infinite options.
  • V shaped treads (which are in most cases a 60 degree "V")
  • buttress shaped treads and square shaped threads.
  • two types of screws are generally utilized depending on the type of bone that is being instrumented (cortical bone vs. cancellous bone).
  • Cortical screws are more like machine screws, meaning that they have a low thread depth and low thread pitch, a useful combination for gaining screw purchase in a hard material.
  • cancellous screws are more like wood screws in that they have a high thread pitch and large thread depth. This combination allows for screw purchase in relatively weak material such as cancellous bone because it allows for a larger amount of bone to be present between each thread thus increasing its strength.
  • pedicle screw fixation (even within the pedicle) is mostly within cancellous bone, most pedicle screws are designed like wood screws.
  • parameters of thread type, shape, pitch, core shape, and size have been determined.
  • V shaped threads are typically utilized with a pitch of approximately 2.8mm and thread depth of approximately 1mm with a core that has a conical shape.
  • Some manufacturers (such as the Xia® screw from Stryker®) have capitalized on these parameters, by producing screws with these specifications that have proven to be successful in clinical use. Therefore, any new screw design can consider incorporation of these previously established design features.
  • bone-implant interfaces are employed to achieve bony fixation. These include: penetrating, gripping, conforming, osteointegration, and abutting interfaces.
  • Current pedicle screw designs primarily take advantage of the penetrating interface to gain fixation into bone. However, in weaker or compromised bone, this single mode may be insufficient to achieve the necessary required fixation. It may be possible to provide additional abutting fixation at the anterior aspect of the pedicle or the junction at which the pedicle connects to the body by changing the shape of the screw at this site (i.e., penetrating and abutting).
  • Other spinal instrumentations work by utilizing other methods of fixation.
  • hooks used in surgery work by gripping the bone, and when cement is used, it functions by conforming to the bone.
  • Another method of fixation depends on bone in or on growth on to the device called osteointegration, which can be expected if the implant is coated with substances such as hydroxyl apatite.
  • the pedicle screw has revolutionized spinal surgery.
  • the lack of sufficiently strong instrumentation for the treatment of patients with compromised bone justifies the need for development of an alternative anchor device.
  • spinal implants are made of an alloy, which is a mixture of metallic elements. These elements commonly include: aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, zirconium, niobium and molybdenum.
  • titanium is used in its pure form to make spinal implants, with four different commercially available grades; grade 1 is the most pure, containing no contaminants, while grade 4 is the least pure. The higher grades have higher moduli of elasticity and increased tensile strength, making them a better option for use in production of spinal instrumentation.
  • the alloys used in the manufacturing of spinal implants and, in particular, pedicle screw systems are: 316L stainless steel, 22-13-5 stainless steel, Co-Cr-Mo and Ti-6A1-4V (a mixture of titanium, aluminum and vanadium).
  • 316L stainless steel 22-13-5 stainless steel
  • Co-Cr-Mo Co-Cr-Mo
  • Ti-6A1-4V a mixture of titanium, aluminum and vanadium.
  • This alloy is popular for spinal instrumentation due to: 1) magnetic resonance imaging (MRI) compatibility with minimal "noise” production compared to other metals, 2) relatively low modulus of elasticity when compared to the other commonly used surgical metals listed above, and 3) decreased allergic reactions compared to metals containing nickel or chromium.
  • MRI magnetic resonance imaging
  • the lower modulus of elasticity allows for a less stiff construct that reduces the phenomenon of stress shielding (i.e., bone resorption), which leads to osteoporosis around implants.
  • stress shielding i.e., bone resorption
  • stainless steel and cobalt chrome continue to be valid options as implant materials for spinal surgery.
  • Some systems utilize a variety of materials for different parts of the system to create a hybrid construct (for example, titanium alloy for the pedicle screw and cobalt chromium for the connecting rods).
  • Design #1 the helix runs nearly the entire length of the screw (referred to as the complete helix).
  • Design #2 the helix is only the end of the screw (referred to the distal helix).
  • Design #3 has the helix in the central region of the screw (referred to as the central helix).
  • the complete helix screw is designed for pedicle fixation in the lumbar spine.
  • the dimensions of the screw are based on the most commonly utilized pedicle screw in the lumbar spine.
  • the length of the screw is 45mm from screw tip to the shaft-head junction.
  • the minor diameter measures 4.5mm while the major diameter is 6.5mm.
  • the threads are V shaped with a 60 degree angle and the thread pitch is set at 2.8mm with a resulting thread depth of 1mm.
  • the pedicle screw body is hollow with a cylindrical bore diameter of 3.0mm.
  • the pedicle screw body is an expanding shell with a grooved, left- handed helix.
  • the direction of the helix is reversed from that of the pedicle screw exterior thread to prevent the helix from unwinding during screw insertion.
  • the pitch of the helix is 5mm. Of notable importance is the angle of the walls of the helix.
  • an inner or central screw actuator is used for the helical screw to expand post-insertion.
  • the inner screw actuator is designed as a standard shaft screw with slight modifications. It has an overall length of 45mm and is threaded at the tip for a total of 25mm with standard M3 threading to match the inner threading of the previously described helical screw tip.
  • the head of this inner screw is designed to accept a 2.5mm Hex driver.
  • the head-body junction is contoured to fit flush against the top of the helical pedicle screw shell upon complete insertion, providing the buttressing force that in turn expands the helical screw shell.
  • the helical pedicle screw shell works by shortening in length during insertion of the inner screw actuator. Once the helix has closed, the walls of the helix come into contact with one another and overlap, causing expansion of the helical screw shell in a circumferential fashion. Furthermore, since the expansion is allowed to occur along the entire length of the helix, the expansion follows the path of least resistance, expanding inside of the vertebral body, abutting against the inner wall of the pedicle for support.
  • the expansion along the path of least resistance is a useful characteristic for an expandable device because it protects against fracture of the pedicle bone or vertebral body if the screw is not placed perfectly in the center of the pedicle bone or vertebral body.
  • This device uses a helical design to allow for reduced resistance during expansion of the pedicle screw post insertion into the pedicle bone.
  • the helix is unique in that it allows for the amount of expansion to be known (i.e., directly related to the number of turns applied to the inner screw actuator), and the surgeon will be able to dial in the amount based on anatomic limitations or patient specific parameters.
  • distal and central helix placement of the helix on the screw can be altered (i.e., distal and central helix).
  • the distal and central helix were identical in every aspect to the complete helix with the exception of location.
  • the helix starts 5mm from the tip and extends towards the head of the screw for a total of 25mm (i.e., leaving the top 15mm of the screw without helix).
  • the central helix has the helix designed into its central aspect with the top and bottom 10mm of the screw not having a helix.
  • the pilot track was followed with a standard straight pedicle probe to a depth of 45mm; it was than rotated 180 degrees in each direction once, prior to removal as per standard surgical technique.
  • the pedicle probe was used to allow the surgeon proprioceptive feedback while creating a passage for the pedicle screw thus minimizing the chance of breakout of the pedicle.
  • Five screws of each type (5 Distal Helix, 5 Central Helix, 5 Complete Helix) were selected and randomized to be inserted into a test site, a pedicle of a Sawbone.
  • 5 size-matched (i.e., 6.5mm by 45mm) screws from the Xia Titanium pedicle screws system were utilized (Stryker, Xia spine system, Kalamazoo, Michigan, USA) and placed in randomized testing sites.
  • the pedicle screws were inserted by hand, maintaining a constant angle and speed by a trained spine surgeon until the entire length of the pedicle screw had entered the vertebra. The screws were stopped 3mm prior to reaching the end of the pedicle screw, which was not dependent on insertional torque.
  • the central screw actuator was inserted in each of the helical pedicle screws to stabilize the pedicle screw during implantation; however, the pedicle screws were not expanded until after they were fully inserted. To produce expansion, all of the helical pedicle screws required application of torque to achieve 20 revolutions on the inner screw actuator, except for the Complete Helix pedicle screws that required 25 revolutions.
  • the specimens were all subsequently imaged using fluoroscopy (C-arm model 850, General Electric Mississauga, ON,) to confirm appropriate screw trajectory and expansion (Figure 6A-6C). Orthogonal views were used to confirm central placement of all pedicle screws within the pedicle. The vertebras were also examined thoroughly to rule out any fractures or defects caused by screw insertion and expansion.
  • Vertebra were then potted in metal boxes using DenstoneTM cement (Heraeus Kulzer Inc., South Bend, IN). To increase fixation, several drywall screws were placed in the vertebra prior to potting, and buried within the Denston. Judicious potting was performed to ensure that the cement did not come into contact with any portion of the pedicle screw. Post testing, examination of the pedicle screws and screw hole was performed to confirm that the Denston had not penetrated the specimen. The potting boxes were mounted on to a materials testing machine (Instron® 8874; Instron, Massachusetts, USA) to allow for axial pullout testing of the pedicle screws.
  • DenstoneTM cement Heraeus Kulzer Inc., South Bend, IN.
  • the pedicle screws were connected to the Instron' s load cell by a custom-made apparatus capable of grabbing a screw head with a low profile.
  • the potted fixture was then attached to a universal joint clamp fixed to the Instron' s base table via a bearing platform designed to allow complete freedom in the x-y planes of motion. Because the fixture was free to move in the x and y directions and the angle of pull was adjustable through the universal joint, the line of pull of each pedicle screw was standardized. In order to ensure that all pedicle screws were positioned vertically prior to pull-out, a 'bulls eye' level was attached to the top of each pedicle screw and the universal joint adjusted until the pedicle screw was vertically positioned.
  • the pedicle screws were then loaded in displacement control at a constant rate of 5mm/minute for a total displacement of 20mm in accordance with published literature on axial pull out testing and standards set by the American Society for Testing and Materials (ASTM). Load and displacement data were collected at 60Hz, resulting in approximately 15000 data points per screw tested. Failure was defined as the maximum load or the load peak prior to decrease in load associated with increasing displacement.
  • ASTM American Society for Testing and Materials
  • right and left sides of each vertebra were tested in random order to lower potential confounding effects of surgical technique. After the pull-out was completed, the specimen and the pedicle screws were closely examined for signs of fracture and damage, and these findings carefully recorded.
  • Additional testing of the complete helix pedicle screw was performed using three fresh froze lumbar cadaveric spines (T12-L5).
  • a total of 16 vertebra or 32 test sites were estimated to be required following a power analysis based on pilot data utilizing a standard deviation of 250, a beta of 0.8 and an alpha of 0.05 to detect a difference equal to or greater than 50% in ultimate failure load. Therefore, six vertebral bodies (T12 to L5) per spine were dissected free of all soft tissues while maintaining the bony elements. All 3 specimens belong to female donors aged 75, 95 and 72 years old, selected due to low bone density. They were examined visually to rule out any bone based defects and scanned using Computed Tomography (GE Discovery 750 HD) to identify any internal bony abnormalities.
  • GE Discovery 750 HD Computed Tomography
  • Helical CT scans were performed with full rotations at 0.6 sec per rotation under high resolution, with scan thickness and interval set at 0.625 mm by 0.625mm. Furthermore, the bone density of each specimen was calculated based on comparison to a known standard phantom bone density placed in the CT scan simultaneously with each specimen. Density is related to Hounsfield units (HU), which were determined for each vertebra using multiple samples from each vertebra. Bone density was subsequently calculated for each specimen.
  • HU Hounsfield units
  • yield load was defined as the load under which the load displacement slope changed (i.e., plastic deformity was noted).
  • Energy was calculated as the area under the load displacement curve to peak load as well as to end of protocol.
  • the average bone density of the 3 specimens was 97 mg/cm3 (Samples: 75 year old female; 95 year old female; 72 year old female).
  • the CT scans obtained from the specimens did not demonstrate any bony abnormalities or fracture.
  • Figure 7 shows a representative load-displacement curve, from which ultimate load, energy to peak, total energy, yield and stiffness were calculated.
  • the mean ultimate failure loads were 623N and 656N for the standard and expandable screw, respectively.
  • mean stiffness was measured at 224 N/mm, while in the expandable screws it was 238 N/mm.
  • the standard screws had yield value of 380 N/mm and the expandable group had a yield value of 484 N/mm.
  • Figure 7 shows an illustrative comparison of energy required to remove the complete helix pedicle screw versus a standard (currently approved for surgical procedures) screw from pedicle bone.
  • the large increase in 'energy to end' needed to remove the complete helix pedicle screw from bone compared to a standard screw in this illustrative example is validated by a significant difference when considering a larger sample size as shown in Figure 8.
  • a large sample size will also show a significant advantage of the complete helix pedicle screw over the standard screw with respect to 'energy to peak' measurements.
  • the anchor device will typically comprise an elongate tubular body defining opposing first and second ends and a longitudinal central axis extending therebetween; the elongate tubular body bound by an exterior surface and an interior surface; the interior surface defining a substantially co-axial lumen extending between the opposing first and second ends; a flanged opening at the first end communicative with the lumen; a helical slit cutout of the tubular body, the helical slit extending from the exterior surface to the interior surface and communicative with the lumen, the helical slit directing circumferential expansion of the tubular body when the tubular body is longitudinally compressed.
  • the helical slit will be continuous for at least 2 full helical rotations to allow for stacking of one helical coil over another. For robustness of the circumferential expansion, the helical slit will typically be continuous for at least 3 full helical rotations.
  • the helical slit may be located anywhere along the tubular body depending upon a desired implementation. Typically, at least a portion of the helical slit will be located at a central region of the tubular body or a region proximal to the second end of the tubular body. For example, if the helical slit begins proximal to the first end, the helical slit will typically continue until it at least reaches a central region of the tubular body.
  • the interior surface and the exterior surface of the tubular body will typically be concentric, but may be offset for a desired implementation.
  • the tubular body will typically be cylindrical or conical such that a radial cross- section yields a circular shape.
  • shape of the tubular body may be modified for a desired implementation, for example, yielding a triangular, square, ellipsoid, pentagon, hexagon or other polygonal radial cross-section.
  • interior and exterior surfaces may be dissimilar shapes such that a radial cross-section could yield, for example, an interior circle and an exterior triangle, square, pentagon, other polygonal shapes, and the like.
  • the anchor device may function by radial or circumferential expansion to abut one or more of the following surfaces that form an access hole in a wall: the co-axial sidewall surface of the access hole which is typically cylindrical, the surface of the wall surrounding the access hole; and an edge or transition at the junction of the sidewall surface and the surrounding wall surface.
  • the anchoring device need not span the entire axial length of the co-axial sidewall surface. For example, where a wall is of sufficient thickness an access hole need not extend from an exterior surface of the wall through to an interior surface. Rather, the access hole is formed to a sufficient depth and the installed anchoring device circumferentially expands to abut the co-axial sidewall surface of the access hole.
  • the anchor device may be configured to be installed in an access hole in various types of walls.
  • the wall may be any naturally occurring or synthesized wall.
  • the wall may be any bone that is typically used as a substrate for installing an anchoring device in a surgical procedure.
  • the wall may be any manufactured wall used in the construction of a product.
  • an implementation of the anchor device could be installed in a dry wall or a cement wall.
  • the flanged opening at the first end may be varied.
  • an extension of the flanged opening to form a tulip head may be useful.
  • a planar flange will typically suffice.
  • the flange may also be omitted for implementations where the anchor device is fully inserted within a hole such that the anchor device is not visible at the surface surrounding the hole.
  • the anchor device has been demonstrated in the drawings as a pedicle screw design comprising a tubular body and a tulip head as a single integrated structure. It should be recognized that the tulip head need not be integral or fixed with the tubular body, but rather may be adjustably coupled to the tubular body to permit additional degrees of freedom upon the tulip head.
  • adjustable coupling including rotational coupling, between the tulip head and tubular body can be found in pedicle screws considered uni-axial, uni-directional, poly-axial, reduction screw, side-loading tulip, medial offset biased, and the like.
  • the angles of the first 52 and second 53 helical edges may be defined with reference to the central axis of the tubular body or with reference to a tangent to the interior surface 21 of the tubular body 12. Also for reference, 0 degrees is towards the first end 14 and parallel to the central axis or tangent of the interior surface, 180 degrees is towards the second end 15 and parallel to the central axis or tangent of the interior surface, and 90 degrees is perpendicular to the central axis or tangent of the interior surface 21.
  • angles of the first 52 and second 53 helical edges may be used.
  • angles of the first 52 and second 53 helical edges may be substantially identical.
  • a differential between the angles of the first helical edge 52 and the second helical edge 53 may be used.
  • the angles of first 52 and second 53 helical edges may be differentiated to benefit a helical slit 50 directed radial expansion of the tubular body 12 upon application of a compressive load to the tubular body 12.
  • identically angled edges provide the greatest contact surface area, while increasing the difference between the angles of the edges correlates to a decrease in the contact surface area.
  • machining tolerances may underlie the observation of increasing angle differential correlating with decreasing compressive load to achieve radial expansion, in that machining tolerances may need to be more stringent when the angle differential is small and contact area is expected to be high.
  • a differential between the angles of the first and second helical edges may allow for one helical edge to provide a ramp for the other helical edge to more predictably direct stacking of one helical edge over the other helical edge (ie. one helical edge stacking either radially inward or outward relative to the other helical edge upon application of a compressive load to the tubular body).
  • the identically angled edges are able to provide predictable stacking and support a useful radial expansion of the tubular body.
  • identical angles of 45 degrees can provide stacking in the same direction as shown in Figure 5C, while identical angles of 135 degrees can provide stacking in the opposite direction.
  • the required compressive load to achieve stacking with identical angles may be reduced by choosing materials and manufacturing techniques that result in relatively low coefficient of friction and/or a smooth finish between the edges. For example, a high polish stainless steel may be suited to accommodate identically angled edges.
  • angles approaching 0 degrees or angles approaching 180 degrees are typically avoided. Angles approaching 0 degrees or 180 degrees typically do not provide sufficient radial expansion and/or may not be accommodated by some conventional manufacturing techniques. Additionally, substantially identical angles approaching 90 degrees may be avoided for implementations where predictable stacking is desired. The use of substantially identical angles approaching 90 degrees may be made more predictable for stacking by design modifications of the anchor device including altering the width of the helical slit, differential rounding of the edges, or tapering of the tubular body and/or inner screw. Although, the use of substantially identical angles of about 90 degrees can achieve a functional result, a better result will typically be achieved by avoiding substantially identical angles of about 90 degrees. Accordingly, most examples of first and second edge angle combinations having substantially identical angles will typically have angles that are non- perpendicular to the central axis or interior surface 21, and have angles non-parallel to the central axis or interior surface 21.
  • first and second helical edges having different angles can achieve radial expansion with a reduced compressive load compared with a pair of substantially identical angles.
  • a typical differential between the angles of the first and second helical edges will be at least 10 degrees.
  • the difference between the angles of the first and second helical edges may be greater than 10 degrees, 20 degrees, 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees or greater than any angle value therebetween.
  • the first and second helical edges may be formed of any combination of acute or obtuse angles such as both angles being acute, both angles being obtuse, or one acute angle and one obtuse angle.
  • combinations including an angle at 90 degrees paired with either an acute or an obtuse angle are also feasible.
  • the pair of different angles of the first and second helical edges will either both be less than or equal to 90 degrees, or both will be greater than or equal to 90 degrees. More typically, the pair of different angles of the first and second helical edges will both be less than or equal to 90 degrees.
  • other pairs of differential angles including a pairing of an acute angle with an obtuse angle, are feasible and can readily be implemented.
  • the difference between the angle of the first and second helical edges can be expressed as a function of the coefficient of friction of a material used to form the tubular body.
  • the difference between the angles may be positively correlated with a coefficient of friction, for example a sliding coefficient of friction of a material on itself.
  • a material with a lower coefficient of friction may need a lower angle differential compared to a material with a higher coefficient of friction which may need a greater angle differential to achieve a similar expansion result given a constant compressive load.
  • the correlation between angle differential and coefficient of friction may accommodate linear, non-linear, or both linear and non-linear relationships.
  • the difference between the angle of the first and second helical edges can also depend upon the absolute value of the angle selected for the first or second edge.
  • This dependency can be illustrated by comparing two different pairs of substantially identical angles so as to simplify this illustration to a single angle value: for example, two comparable constructs distinguished by first and second edge angles of 40 degrees/40 degrees compared to 80 degrees/80 degrees.
  • the 40/40 construct will require a lesser compressive load.
  • the angle differential can be positively correlated with the value of the angle, so that a lesser acute angle would need a smaller angle differential compared to the angle differential for a greater acute angle to achieve a similar expansion result given a constant compressive load.
  • angle differential can be negatively correlated with the value of the angle, so that a greater obtuse angle would need a smaller angle differential compared to the angle differential for a lesser obtuse angle to achieve a similar expansion result given a constant compressive load.
  • the correlation between angle differential and the absolute value of an angle may accommodate linear, non-linear, or both linear and non-linear relationships.
  • RMAX maximum expected radial expansion (assuming that all of the axial contraction causes a single section of the helix to rise over its adjacent section)
  • y initial length of the engaged threads when the screw actuator 80 begins to buttress against the tulip's resting chamfer (chamfered opening 26 at first end 14 of tubular body 12)
  • g gap length between either edge of the helical slit 50
  • n number of helical gaps that cross a straight line running from the tulip to the tip of the tubular body 12.
  • ⁇ angle of rise
  • the parameters of the RMAX relationship are shown in Figure 9 with an example of a radial expansion plot under test conditions of compressive load application without external impediment of an access hole wall material. As shown in the sample radial expansion plot, expansion is not expected to be the same everywhere along the helix due to stiffness changes. RMAX is expected to occur at or near a central portion of the helix, with minimal or no expansion at the initiation and termination of the helical slit.
  • the angle of rise ⁇ could be either of the first 52 or second 53 edges depending on the design of an implementation. It is apparent from the RMAX relationship as well as Figure 9 that the angle of rise accommodates values of 0 to 90 degrees. If the first or second edge is an obtuse angle then 180 degrees can be used as a reference angle to determine the angle of rise, for example the obtuse value can be subtracted from 180 degrees.
  • angles approaching 0 degrees or 180 degrees typically do not support sufficient radial expansion and/or may not be accommodated by some conventional manufacturing techniques.
  • An angle less than 5 degrees or greater than 175 degrees will generally be avoided.
  • the first and second edges may be cut at angles that range from about 5 degrees to about 175 degrees.
  • angles of the first and second edges may be greater than 5 degrees, 10 degrees, 15 degrees, 20 degrees or greater than any angle value therebetween.
  • angles of the first and second edges may be less than 175 degrees, 170 degrees, 165 degrees, 160 degrees or less than any angle value therebetween.
  • First 52 and second 53 edges have been shown in the drawings as having a straight or linear profile.
  • a non-linear profile may include any type of curve, including for example a convex curve, a concave curve, a sinusoidal curve, and the like.
  • an edge profile may be bi-phasic with a first linear portion having a first angle transitioning to a second linear portion having a second angle.
  • the transition of the first linear portion to the second linear portion may be mediated by a connecting curve.
  • an edge profile may be a curve of varying angulation.
  • an edge may comprise one or more linear or non-linear profile or profile portion.
  • an edge may comprise any type of fillet, chamfer, bevel, and the like at the inner and/or outer corners of its profile.
  • a helical thread 27 formed in the interior surface 21 at or proximal to the second end 15 to engage the thread of the screw actuator 80 may be clockwise or counter-clockwise depending on the implementation. Typically, to be consistent with conventional practice the threading will be clockwise. Furthermore, a threading of the interior surface 21 may be avoided for actuators that are not screw actuators. Actuators will typically have an anchor point connection at or near the second end 15 of the tubular body. For screw actuators the anchor point connection is a threaded engagement. For other actuators the threading may be unnecessary.
  • An opening at the second end 15 is optional.
  • an opening at the second end 15 allows for the helical thread 27 to be shorter and or located in greater proximity to the second end 15 compared to a similar construct with a closed second end. Furthermore, for actuators other than screw actuators an opening at the second end 15 may be unnecessary.
  • Materials for forming the tubular body and the screw actuator may be varied depending on the specific implementation. Materials will typically be selected to avoid complications from incompatible oxidation or electrochemical potentials. Furthermore, dissimilar materials for the tubular body and screw actuator may be useful to reduce the possibility of locking (cold weld) due to a similar yield point. For the specific case of bone installation or fixation, a titanium tubular body and a cobalt chrome screw actuator has been found to be useful. Materials used may encompass any biocompatible metal, polymer or combinations thereof.
  • Examples of materials that may be used to form an anchor device include metals such as stainless steel alloys, nickel titanium alloys, surgical grade titanium alloy (for example, Ti- 6AI-4V, ASTM F 136), commercially pure titanium (for example, Ti-CP2, ASTM F 67) with or without an electrolytic conversion coating, cobalt-chrome alloys, nickel-cobalt alloys, molybdenum alloys, tungsten-rhenium alloys, and polymers such as polyethylene teraphathalate (PET), polyester, polypropylene, ultra high molecular weight polyethylene (i.e., extended chain, high-modulus or high-performance polyethylene) fiber and/or yarn, polytetrafluoroethylene (PTFE), expanded PTFE (ePTFE), polyether ketone (PEK), polyether ether ketone (PEEK), poly ether ketone ketone (PEKK) (also poly aryl ether ketone ketone), nylon, polyether-block co-polyamide polymers, ali
  • the exterior helical thread 40 may be omitted or substituted with other engaging structures such as teeth or ribs. Substitutes may include any outward projection such as outwardly extending teeth, ribs, hooks, collar, flange, and the like.
  • the exterior helical thread may be oriented clockwise or counter-clockwise provided that it is in opposing orientation to the helical slit. To be consistent with conventional practice, the exterior helical thread will typically be oriented for clockwise rotation.
  • the anchor device comprises: an elongate tubular body defining opposing first and second ends and a longitudinal central axis extending therebetween; the elongate tubular body bound by an exterior surface and an interior surface; the interior surface defining a co-axial lumen extending between the opposing first and second ends; an opening at the first end communicative with the lumen; a helical slit within the tubular body, the helical slit extending from the exterior surface to the interior surface and communicative with the lumen, the helical slit directing circumferential expansion of the tubular body when the tubular body is longitudinally compressed.
  • Anchor devices and related methods for stabilizing bones and/or bone segments are contemplated.
  • Anchor devices can be surgically installed for bone implantation, stabilization, fixation and the like, into bone tissue (e.g., spinal structure, vertebrae, cancellous bone, cortical bone, etc.) in order to stabilize bones and/or bone segments.
  • bone tissue e.g., spinal structure, vertebrae, cancellous bone, cortical bone, etc.
  • an anchor device may be installed or implanted in bone and/or bone segments to fasten different elements to spinal structure, to fasten fusion rods between adjoining vertebrae, to fasten the left and right side pedicles of the same vertebra together, or to connect bones or sections of the same bone in other parts of the body such as pelvic, hip or femur bones (e.g., to stabilize bones and/or bone segments that have become displaced and/or unstable due to fractures or the like).
  • methods of surgical treatment of an orthopedic disorder or condition comprising installation of a suitable anchor device are contemplated.
  • Various uses of the anchor device to treat an orthopedic disorder or condition are also contemplated.
  • Methods of medical treatment and medical use may include any indication that could benefit from spinal stabilization such as an indication of a spinal disorder or condition, including for example, scoliosis, kyphosis, spondylolisthesis, spinal stenosis, persistent sciatica, spinal deformities, degenerative lumbar disease, segmental instability, disc degeneration or fracture caused by disease or trauma or congenital defects, or degeneration caused by tumors, autoimmune disease, osteoporosis, and the like.
  • spinal stabilization such as an indication of a spinal disorder or condition, including for example, scoliosis, kyphosis, spondylolisthesis, spinal stenosis, persistent sciatica, spinal deformities, degenerative lumbar disease, segmental instability, disc degeneration or fracture caused by disease or trauma or congenital defects, or degeneration caused by tumors, autoimmune disease, osteoporosis, and the like.
  • the anchor device may incorporate features of and/or may be suitable for use as replacements or alternatives for any number of existing orthopedic devices including for example, lag screws, compression hip screws, plate screws, fragment fixation screws, acetabular cup fixation screws, pedicle screws, and the like.
  • Design parameters of anchor devices including, for example, angles of first and second edges, optional angle differential of the edges, optional deviation from single linear profile of edges, width of helical slit, number of rotations of helical slit, actuator type, material of the actuator, actuator operational length or more particularly a screw actuator operational thread length, tubular body shape, material of the tubular body, tubular body wall thickness, tubular body length, tubular body diameter, optional flange at the first end of the tubular body, optional opening at the second end of the tubular body, optional interior threading at or proximal to the second end of the tubular body, optional exterior threading of the tubular body can all be varied or modified individually or in any combination and can be readily tested for suitability and usefulness for a desired implementation using experimental tests described herein or any other available testing protocol available to the person of skill in the art.

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  • Health & Medical Sciences (AREA)
  • Orthopedic Medicine & Surgery (AREA)
  • Life Sciences & Earth Sciences (AREA)
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  • Neurology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Engineering & Computer Science (AREA)
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Abstract

La présente invention concerne un dispositif d'ancrage pour installation dans un trou d'accès formé dans une paroi, le dispositif d'ancrage comprenant : un corps tubulaire allongé définissant les première et deuxième extrémités opposées et un axe central longitudinal s'étendant entre celles-ci ; le corps tubulaire allongé délimité par une surface extérieure et une surface intérieure concentrique ; la surface intérieure définissant une lumière coaxiale s'étendant entre les première et deuxième extrémités opposées ; une ouverture bridée à la première extrémité communiquant avec la lumière ; un filet hélicoïdal s'étendant radialement vers l'extérieur depuis la surface extérieure du corps tubulaire ; une découpe de fente hélicoïdale du corps tubulaire en orientation inverse par rapport au filet hélicoïdal, la fente hélicoïdale s'étendant de la surface extérieure à la surface intérieure et communiquant avec la lumière, la fente hélicoïdale dirigeant l'expansion circonférentielle du corps tubulaire lorsque le corps tubulaire est longitudinalement comprimé.
PCT/CA2014/051254 2013-12-23 2014-12-22 Dispositif d'ancrage Ceased WO2015095965A1 (fr)

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Cited By (6)

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Publication number Priority date Publication date Assignee Title
KR101837434B1 (ko) * 2017-07-11 2018-04-20 (주)오스테오닉 상호 연결된 수직스플릿과 수평스플릿을 구비하는 봉합사 앵커
GB2562586A (en) * 2012-10-02 2018-11-21 Alphatec Spine Inc Expandable screw and methods of use
WO2020178409A1 (fr) * 2019-03-05 2020-09-10 Sota Orthopaedics Ltd. Appareil à boulon pour fixation vertébrale
US20230084223A1 (en) * 2021-09-16 2023-03-16 Dingjun Hao Claw-shaped pedicle screw fastener for osteoporosis
US12349951B2 (en) 2021-03-11 2025-07-08 Bfm Holdings, Llc Double helix bone screw
WO2026002905A1 (fr) * 2024-06-24 2026-01-02 Orthofuse Ltd Attache pour fixation osseuse

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CA2109244A1 (fr) * 1992-10-29 1994-04-30 Per-Ingvar Branemark Element d'ancrage de protheses ou mecanisme d'articulation pour articulations reconstruites
CA2122192A1 (fr) * 1993-04-27 1994-10-28 Per-Ingvar Branemark Element d'ancrage pour l'implantation tissulaire ou la fixation de protheses, de composantes articulaires artificielles ou d'autres elements semblables
US20110071579A1 (en) * 2008-06-20 2011-03-24 Reach Jr John S Porous expansion bolt
US20110144703A1 (en) * 2009-02-24 2011-06-16 Krause William R Flexible Screw
US20120172934A1 (en) * 2011-01-04 2012-07-05 Fisher Michael A Expansion Screw Bone Tamp
US20140277192A1 (en) * 2013-03-14 2014-09-18 Smith & Nephew, Inc. Reduced area thread profile for an open architecture anchor

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Publication number Priority date Publication date Assignee Title
CA2109244A1 (fr) * 1992-10-29 1994-04-30 Per-Ingvar Branemark Element d'ancrage de protheses ou mecanisme d'articulation pour articulations reconstruites
CA2122192A1 (fr) * 1993-04-27 1994-10-28 Per-Ingvar Branemark Element d'ancrage pour l'implantation tissulaire ou la fixation de protheses, de composantes articulaires artificielles ou d'autres elements semblables
US20110071579A1 (en) * 2008-06-20 2011-03-24 Reach Jr John S Porous expansion bolt
US20110144703A1 (en) * 2009-02-24 2011-06-16 Krause William R Flexible Screw
US20120172934A1 (en) * 2011-01-04 2012-07-05 Fisher Michael A Expansion Screw Bone Tamp
US20140277192A1 (en) * 2013-03-14 2014-09-18 Smith & Nephew, Inc. Reduced area thread profile for an open architecture anchor

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2562586A (en) * 2012-10-02 2018-11-21 Alphatec Spine Inc Expandable screw and methods of use
JP2018192257A (ja) * 2012-10-02 2018-12-06 アルファテック スパイン， インコーポレイテッド 拡張可能なネジ及び使用方法
US10695115B2 (en) 2012-10-02 2020-06-30 Alphatec Spine, Inc. Expandable screw and methods of use
KR101837434B1 (ko) * 2017-07-11 2018-04-20 (주)오스테오닉 상호 연결된 수직스플릿과 수평스플릿을 구비하는 봉합사 앵커
WO2020178409A1 (fr) * 2019-03-05 2020-09-10 Sota Orthopaedics Ltd. Appareil à boulon pour fixation vertébrale
US12349951B2 (en) 2021-03-11 2025-07-08 Bfm Holdings, Llc Double helix bone screw
US20230084223A1 (en) * 2021-09-16 2023-03-16 Dingjun Hao Claw-shaped pedicle screw fastener for osteoporosis
US11793550B2 (en) * 2021-09-16 2023-10-24 Dingjun Hao Claw-shaped pedicle screw fastener for osteoporosis
WO2026002905A1 (fr) * 2024-06-24 2026-01-02 Orthofuse Ltd Attache pour fixation osseuse

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