Patent Application
20100036434
This disclosure relates generally to spinal implants, and more particularly to spinal implants and methods for reducing and attaching spinal stabilization rods to boney structures (such as vertebrae) when the spinal stabilization rods may be proud of their intended position by some distance.
The human spine consists of segments known as vertebrae separated by intervertebral disks and held together by various ligaments. There are 24 movable vertebrae—7 cervical, 12 thoracic, and 5 lumbar. Each of the movable vertebra has a somewhat cylindrical bony body (often referred to as the centrum), a number of winglike projections, and a bony arch. The bodies of the vertebrae form the supporting column of the skeleton. The arches of the vertebrae are positioned so that the spaces they enclose form a curvilinear passage which is often referred to as the vertebral canal. The vertebral canal houses and protects the spinal cord (which includes bundles of sensory and motor nerves for sensing conditions in or affecting the body and commanding movements of various muscles). Within the vertebral canal, spinal fluid can circulate to cushion the spinal cord and carry immunological cells to it, thereby protecting the sensory and motors nerves therein from mechanical damage and disease. Ligaments and muscles are attached to various projections of the vertebrae such as the superior-inferior, transverse, and spinal processes. Other projections, such as vertebral facets, join adjacent vertebrae to each other, in conjunction with various attached muscles, tendons, etc. while still allowing the vertebrae to move relative to each other.
Spines may be subject to abnormal curvature, injury, infections, tumor formation, arthritic disorders, punctures of the intervertebral disks, slippage of the intervertebral disks from between the vertebrae, or combinations thereof. Injury or illness, such as spinal stenosis and prolapsed disks may result in intervertebral disks having a reduced disk height, which may lead to pain, loss of functionality, reduced range of motion, disfigurement, and the like. Scoliosis is one relatively common disease which affects the spinal column. It involves moderate to severe lateral curvature of the spine and, if not treated, may lead to serious deformities later in life. Such deformities can cause discomfort and pain to the person affected by the deformity. In some cases, various deformities can interfere with normal bodily functions. For instance, some spinal deformities can cause the affected person's rib cage to interfere with movements of the respiratory diaphragm, thereby making respiration difficult. Additionally, some spinal deformities noticeably alter the posture, gate, appearance, etc. of the affected person, thereby causing both discomfort and embarrassment to those so affected. One treatment involves surgically implanting devices to correct such deformities, to prevent further degradation, and to mitigate symptoms associated with the conditions which may be affecting the spine.
Modern spine surgery often involves spinal stabilization through the use of spinal implants or stabilization systems to correct or treat various spine disorders and/or to support the spine. Spinal implants may help, for example, to stabilize the spine, correct deformities of the spine, facilitate fusion of vertebrae, or treat spinal fractures and other spinal injuries. Spinal implants can alleviate much of the discomfort, pain, physiological difficulties, embarrassment, etc. that may be associated with spinal deformities, diseases, injury, etc.
Spinal stabilization systems typically include corrective spinal instrumentation that is attached to selected vertebra of the spine by bone anchors, screws, hooks, clamps, and other implants hereinafter referred to as “bone anchors.” Some corrective spinal instrumentation includes spinal stabilization rods, spinal stabilization plates that are generally parallel to the patients back, or combinations thereof In some situations, corrective spinal instrumentation may also include superior-inferior connecting rods that extend between bone anchors (or other attachment instrumentation) attached to various vertebrae along the affected portion of the spine and, in some situations, adjacent vertebrae or adjacent boney structures (for instance, the occipital bone of the cranium or the coccyx). Spinal stabilization systems can be used to correct problems in the cervical, thoracic, and lumbar portions of the spine, and are often installed posterior to the spine on opposite sides of the spinous process and adjacent to the superior-inferior process. Some implants can be implanted anterior to the spine and some implants can be implanted at other locations as selected by surgical personnel such as at posterior locations on the vertebra.
Often, spinal stabilization may include rigid support for the affected regions of the spine. Such systems can limit movement in the affected regions in virtually all directions. Such spinal stabilizations are often referred to as “static” stabilization systems and can be used in conjunction with techniques intended to promote fusion of adjacent vertebrae in which the boney tissue of the vertebrae grow together, merge, and assist with immobilizing one or more intervertebral joints. More recently, so called “dynamic” spinal stabilization systems have been introduced wherein the implants allow at least some movement (e.g., flexion or extension) of the affected regions of the spine in at least some directions. Dynamic stabilization systems therefore allow the patient greater freedom of motion at the treated intervertebral joint(s) and, in some cases, improved quality of life over that offered by static stabilization systems.
One embodiment provides an instrument for reducing a spinal stabilization rod into a bone anchor using a closure member. The rod reduction instrument can include a body, an alignment feature, and a flange. The instrument alignment feature can correspond to the bone anchor alignment feature. The instrument flange can be at the distal end of the rod reduction instrument and can be adapted for mounting the rod reduction instrument on the bone anchor. The instrument body can define a threaded slot which extends between the proximal end of the rod reduction instrument and the instrument flange at the distal end of the rod reduction instrument. The instrument slot can correspond to a slot of the bone anchor. The instrument alignment features and the bone anchor alignment features can align the threads of the instrument slot and the threads of the bone anchor to form substantially continuous threads when the rod reduction instrument is mounted on the bone anchor. The instrument alignment features and the bone anchor alignment features can be, respectively, a pin and a corresponding hole oriented in a radial direction relative to the longitudinal axis of the rod reduction instrument.
In some embodiments, the rod reduction instrument can include an alignment feature actuator coupled to the instrument alignment feature to actuate the instrument alignment feature by pivoting about an actuator gusset of the instrument. The alignment feature actuator can bias the instrument alignment feature radially toward the bone anchor alignment feature when the rod reduction instrument is mounted on the bone anchor. The alignment feature actuator can define a slot corresponding to the instrument slot. In some embodiments, the instrument slot can include a thread transition portion across which the instrument threads transition from one diameter to another diameter. The instrument threads can include an anti-splay feature to prevent the instrument slot walls from splaying when the spinal stabilization rod is reduced through the instrument slot.
One embodiment provides a method of reducing a spinal stabilization rod into a bone anchor. The spinal stabilization rod reduction method can include receiving the spinal stabilization rod in a slot of a rod reduction instrument. The closure member may also be received in the instrument slot. The method of reducing a spinal stabilization rod can further include mounting the rod reduction instrument to the bone anchor. Threads of the instrument and threads of the bone anchor can be aligned with each other so that the instrument threads and the bone anchor threads form substantially continuous threads along the instrument and bone anchor slots. The closure member may be driven along the substantially continuous threads to urge the spinal stabilization rod into the bone anchor. While the closure member is being driven, splaying of the instrument slot walls can be prevented.
In some embodiments, the method of reducing a spinal stabilization rod can include driving the closure member along a thread transition portion of the instrument threads. Across the thread transition portion, the instrument threads can transition from one diameter to another diameter. Aligning the instrument threads and the bone anchor threads can include actuating an alignment feature actuator of the instrument to urge an alignment feature of the instrument away from the bone anchor and can include receiving the spinal stabilization rod in a slot of the actuator (which can correspond to the instrument slot). The method of reducing a spinal stabilization rod can include allowing the alignment feature actuator to urge the instrument alignment features toward alignment features of the bone anchor. Actuation of the alignment feature actuator can include pivoting the alignment feature actuator to cause a portion of the alignment feature actuator to move in a radial direction relative to the rod reduction instrument.
One embodiment provides a kit for reducing a spinal stabilization rod using a closure member. The rod reduction kit can include a bone anchor and a rod reduction instrument. The bone anchor can define a slot for receiving the spinal stabilization rod and the closure member. The bone anchor can include an alignment feature and a wall of the bone anchor slot. The wall of the bone anchor slot can define threads. The rod reduction instrument can include a body, another alignment feature, and a flange. The instrument alignment feature can correspond to the bone anchor alignment feature. The instrument flange can be at the distal end of the rod reduction instrument and can be adapted for mounting the rod reduction instrument on the bone anchor. The rod reduction instrument can define another slot which extends between the proximal end of the rod reduction instrument and the instrument flange at the distal end of the rod reduction instrument. The instrument and bone anchor slots can correspond to each other.
The instrument slot wall can include threads along a portion of the instrument slot wall and can include an anti-splay feature and a thread transition portion. The instrument alignment features and the bone anchor alignment features can align the instrument threads and bone anchor threads to form substantially continuous threads when the rod reduction instrument is mounted on the bone anchor. The instrument and bone anchor alignment features can be, respectively, a pin and a hole oriented in a radial direction relative to the longitudinal axis of the instrument. The instrument alignment features can be urged toward the bone anchor alignment features by an alignment feature actuator.
In some embodiments, an alignment feature actuator can be a sleeve slidably engaging a member coupled to the instrument alignment feature. The sleeve can lock the instrument alignment feature in a position wherein the instrument alignment feature is engaged with an anchor alignment feature by holding the member against the body of the instrument.
Embodiments disclosed herein provide many advantages. For example, some embodiments provide rod reduction instruments and methods of reducing spinal stabilization rods in which closure members can be driven across the transition from threads of the rod reduction instrument to threads of a bone anchor substantially without binding or loosing mechanical advantage. Some embodiments provide rod reduction instruments and methods of reducing spinal stabilization rods which can align the instrument and bone anchor threads without disturbing tissues which might be proximal to the rod reduction instrument and bone anchor. Some embodiments allow surgical personnel to actuate alignment features of the rod reduction instrument by grasping an ergonomically shaped and dimensioned portion of the rod reduction instrument and alignment feature actuators thereof. Some embodiments allow surgical personnel to advance a closure member relatively rapidly through the body of a rod reduction instrument. Some embodiments allow surgical personnel to drive the closure member against the spinal stabilization rod despite reactions of the spinal stabilization rod arising from its reduction into a bone anchor.
These, and other, aspects will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. The following description, while indicating various embodiments and numerous specific details thereof, is given by way of illustration and not of limitation. Many substitutions, modifications, additions or rearrangements may be made within the scope of the disclosure, and the disclosure includes all such substitutions, modifications, additions or rearrangements.
A more complete understanding of the present disclosure and the advantages thereof may be acquired by referring to the following description, taken in conjunction with the accompanying drawings in which like reference numbers indicate like features and wherein:
The disclosure and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments detailed in the following description. Descriptions of well known starting materials, manufacturing techniques, components, and equipment are omitted so as not to unnecessarily obscure the disclosure in detail. Skilled artisans should understand, however, that the detailed description and the specific examples, while disclosing preferred embodiments of the disclosure, are given by way of illustration only and not by way of limitation. Various substitutions, modifications, and additions within the scope of the underlying inventive concept(s) will become apparent to those skilled in the art after reading this disclosure. Skilled artisans can also appreciate that the drawings disclosed herein are not necessarily drawn to scale.
As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, process, article, or apparatus that comprises a list of elements is not necessarily limited only those elements but may include other elements not expressly listed or inherent to such process, process, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).
Additionally, any examples or illustrations given herein are not to be regarded in any way as restrictions on, limits to, or express definitions of, any term or terms with which they are utilized. Instead, these examples or illustrations are to be regarded as being described with respect to one particular embodiment and as illustrative only. Those of ordinary skill in the art will appreciate that any term or terms with which these examples or illustrations are utilized will encompass other embodiments which may or may not be given therewith or elsewhere in the specification and all such embodiments are intended to be included within the scope of that term or terms. Language designating such nonlimiting examples and illustrations includes, but is not limited to: “for example”, “for instance”, “e.g.”, “in one embodiment”.
However, certain conditions can cause damage to spine 10, vertebrae 12, certain intervertebral discs, etc. and can impede the ability of spine 10 to move in various manners. These conditions include, but are not limited to abnormal curvature, injury, infections, tumor formation, arthritic disorders, puncture, or slippage of the intervertebral disks, and injuries or illness such as spinal stenosis and prolapsed disks. As some of these conditions progress, come into existence, or persist, various symptoms can indicate the desirability of stabilizing spine 10 or curing deformities thereof. As a result of these various conditions, the ability of the patient to move, with or without pain or discomfort, can be impeded. Additionally, certain physiological processes such as breathing can be impeded by such conditions. Based on various indications, medical personnel might recommend attaching one or more spinal stabilization or correction systems (hereinafter spinal stabilization systems) to vertebra 12 of spine 10 (among other possible remedial actions such as physical therapy) to correct the particular condition(s) from which the patient may be suffering and to prevent further deterioration of spine 10, vertebra 12, etc.
With continuing reference to
However, due to various chronic, degenerative, genetic, etc. conditions, spine 10 can be deformed and, in some cases, deformed in significant manners. With reference to
In some situations, it may be difficult for surgical personnel to reduce spinal stabilization rod 24 into the particular bone fastener assembly 26. For instance, if spinal stabilization rod 24 happens to be proud of its intended position in a particular bone fastener assembly 26 by a distance which places it outside of the particular bone fastener assembly 26, closure member 28 cannot engage the internal threads of the particular bone fastener assembly 26 to reduce spinal stabilization rod 24 into position. Moreover, because spine 10 and the anatomical features coupled thereto may resist movement of spinal stabilization rod 24, it may be difficult for surgical personnel to force spinal stabilization rod 24 into the particular bone fastener assembly 26 absent certain mechanical advantages provided by internal threads of bone fastener assembly 26. Previously, surgical personnel might have had to remove spinal stabilization rods 24, bone fastener assemblies 26, and potentially other portions of spinal stabilization system 22 and attempt to stabilize spine 10 with different spinal stabilization system components or different spinal stabilization systems altogether. Because of the additional surgical steps (and surgical operating time associated there with), the patient can suffer additional trauma to tissues in (or adjacent to) the surgical site, post-operative complications, discomfort, pain, etc.
With reference now to
Instrument flange 107 may be shaped, dimensioned, etc. or otherwise adapted to mount rod reduction instrument 100 on bone anchor 102. Actuator gussets 112 of rod reduction instrument 100 may be formed integrally with instrument body 106 or can be formed separately and coupled to instrument body 106 by welding, brazing, using fasteners, etc. Actuator gussets 112 may be positioned toward the distal end of instrument body 106 and can be positioned to provide surgical personnel who might be using rod reduction instrument 100 some mechanical advantage when actuating alignment feature actuators 108. In some embodiments, actuator gussets 112 can be positioned on instrument body 106 sufficiently distant from the distal end of rod reduction instrument 100 so that, when rod reduction instrument 100 is mounted to bone anchor 102, actuator gussets 112 will lie outside of most, if not all, patients' bodies.
Alignment feature actuators 108 can be bars or other generally elongated shapes suitable for pivotably coupling to actuator gussets 112 and for supplying surgical personnel some mechanical advantage when actuating instrument alignment features 110. Alignment feature actuators 108 can extend some distance parallel to longitudinal axis 116 from actuator gussets 112 and toward the proximal end of rod reduction instrument 100. Alignment feature actuators may be sufficiently long so as to allow surgical personnel to grasp the proximal ends of alignment feature actuators 108 when rod reduction instrument 100 is mounted to bone anchor 102. Alignment feature actuators 108 may extend from actuator gussets 112 toward, and beyond, the distal end of rod reduction instrument 100 and, more particularly, beyond instrument flange 107 so that, when rod reduction instrument 100 is mounted on bone anchor 102 (by instrument flange 107), instrument alignment features 110 can engage corresponding alignment features of bone anchor 102. In some embodiments, alignment feature actuators 108 can be biased so that their distal ends are urged in a radial direction toward, or away from instrument body 106, although alignment feature actuators 108 need not be biased in any direction. In some embodiments, alignment feature actuators 108 can be oriented along superior-inferior axis 121 when rod reduction instrument 100 is mounted on bone anchor 102. Alignment feature actuators 108 can be formed integrally with instrument alignment features 110 or they can be formed separately and coupled together by welding, brazing, using fasteners, etc.
Instrument alignment features 110 can correspond to alignment features of bone anchor 102 (see
At this juncture, it may be useful to discuss aspects of bone anchor 102. Bone anchor 102 can define bone anchor flange 109 on which instrument 100 may be mounted via instrument flange 107. Thus, instrument flange 107 and bone anchor flange 109 may correspond to each other. Bone anchor 102 can further define an internal slot (discussed further herein) for accepting spinal stabilization rod 24. Bone anchor 102 can also include threaded member 114 or other attachment mechanism for attaching bone anchor 102 to vertebrae 12 (or other boney structures).
In operation, surgical personnel may open a surgical site in a patient's body, distract muscles, nerves, arteries, veins, organs, etc. which might be proximal to vertebra 12 (or some other selected boney structure) to which surgical personnel may desire to attach spinal stabilization system 22 (including one or more bone anchors 102). Surgical personnel may then attach bone anchor 102 to vertebrae 12 along with attaching other bone anchors 102 to other vertebrae 12. Spinal stabilization rod 24 may be placed in one or more bone anchors 102 and positioned so that spinal stabilization rod 24 extends in a direction generally parallel to superior-inferior axis 121 to a position proximal to a particular bone anchor 102 of
Surgical personnel may navigate rod reduction instrument 100 so that instrument flange 107 contacts bone anchor flange 109 of bone anchor 102 with spinal stabilization rod 24 in the internal slot of rod reduction instrument 100. Depending on whether, and in which direction, alignment feature actuators 108 are biased (if it all), surgical personnel may actuate alignment feature actuators 108 to provide clearance between instrument alignment features 110 and bone anchor 102 while instrument flange 107 is brought into contact with bone anchor flange 109. Actuation of alignment feature actuators 108 can be by way of grasping alignment feature actuators 108 at a location proximal from actuator gussets 112 and causing alignment feature actuators 108 to pivot about actuator gussets 112. Rod reduction instrument 100 can be rotated about longitudinal axis 116, or otherwise oriented, to bring instrument alignment features 110 into registry with alignment features of bone anchor 102. Surgical personnel may then release, or actuate, alignment feature actuators 108 to cause instrument alignment features 110 to engage alignment features of bone anchor 102. Instrument alignment features 110, in conjunction with corresponding alignment features of bone anchor 102, can hold rod reduction instrument 100 and bone anchor 102 in fixed relationship to each other as explained herein.
Closure member 104 can be brought into the proximity of the proximal end of rod reduction instrument 100. As discussed previously, instrument body 106 can define a slot at its distal end for accepting spinal stabilization rod 24. This instrument slot (not shown in
With continuing reference to
At some time, surgical personnel can discontinue driving closure member 104 through either rod reduction instrument 100 or through bone anchor 102 as may be desired. Screwdriver(s), and any other instruments which might be in rod reduction instrument 100, can be withdrawn. Alignment feature actuators 108 can be actuated (or released depending on biasing arrangements associated with alignment feature actuators 108) to disengage instrument alignment features 110 from alignment features of bone anchor 102. Surgical personnel may withdraw rod reduction instrument 100 from bone anchor 102 and the surgical site and close the surgical site if desired. Rod reduction instrument 100 may be used to reduce spinal stabilization rod 24 into additional bone anchors 102 attached to other vertebrae 12 or boney structures. Rod reduction instrument 100 can also be used to reduce additional spinal stabilization rods into other bone anchors which may be positioned on the opposite side of spinous process 16 (see
Now with reference to
As noted previously,
Instrument alignment features 110, bone anchor alignment features 111, instrument threads 118, and bone anchor threads 122 can be positioned and oriented relative to each other so that when instrument alignment features 110 engage bone anchor alignment features 111, the distal end of instrument threads 118 align with the proximal end of bone anchor threads 122. In some embodiments, the transition between instrument threads 118 and bone anchor threads 122 can be sufficiently gradual so that threads of closure member 104 (see
Rod reduction instrument 100 can define thread transition portion 130 of instrument slot 117 across which instrument threads 118 can transition from diameter d1 to another diameter d2. Diameter d1 of instrument threads 118 toward the proximal end of instrument body 106 from thread transition portion 130 can correspond to, but slightly exceed, diameter d3 (see
Rod reduction instrument 100 can define body transition portion 132 of instrument body 106 across which instrument body 106 can transition from one thickness to another thickness. Body transition portion 132 can be located at a place along instrument body 106 which is likely to be external to the bodies of most patients when rod reduction instrument 100 is mounted on bone anchor 102. Body transition portion 132 can allow surgical personnel to grasp a more ergonomically dimensioned proximal end of instrument body 106 while minimizing effects on surrounding tissues of the distal end of instrument body 106. Rod reduction instrument 100 can define width transition portion 133 where instrument body 106 transitions from one width w1 to another width w2. Thus, width transition portion 133 can allow the thinner and less intrusive distal end of rod reduction instrument 100 (as compared to the proximal end of instrument body 106) to be navigated within the patients' bodies. Width transition portion 133 can provide clearance between distal portions of alignment feature actuators 108 and instrument slot walls 124 thereby allowing instrument alignment features 110 to engage bone anchor alignment features 111. Alignment feature actuators 108 may define actuator transition portion 134 to be discussed in more detail with reference to
Bone anchor 102 can include a bone anchor socket (defined by bone anchor gusset 138) at the distal end of bone anchor 102. Such bone anchor sockets can be shaped, dimensioned, etc. to receive and retain a head portion (not shown) of threaded member 114 (see
With continuing reference to
Bone anchor 102 can define bone anchor gusset 138 which can provide sufficient material about bone anchor socket 136 to withstand reactions between bone anchor 102 and threaded member 114. Bone anchor gusset 138 can also be dimensioned, shaped, etc. to spread forces onto vertebra 12 (or other boney structures to which threaded member 114 can attach bone anchor 102) which might otherwise be concentrated on portions of vertebra 12 should bone anchor 102 come into abutting relationship with vertebra 12. Thus, bone anchor gusset 138 can alleviate various forces which might act on the surface of vertebra 12 while assisting with maintaining the structural integrity and functionality of spinal stabilization system 22 (see
With reference now to
As illustrated by
With reference now to
Actuator gussets 112 may be positioned on superior and inferior surfaces of instrument body 106 and can form part of actuator hinge 154. Second instrument alignment feature 142, second bone anchor alignment feature 144, and alignment locking pin 146 can be located on medial/lateral surfaces of instrument body 106. Being placed on medial/lateral surfaces of instrument body 106 and bone anchor 102, second instrument alignment feature 142 and second bone anchor alignment feature 144 can be positioned sufficiently distant from alignment feature actuators 108 and instrument slots 117 so that actuation of instrument alignment features 110 and reduction of spinal stabilization rod 24 is not affected by the location of second instrument alignment feature 142, second bone anchor alignment feature 144, or alignment locking pin 146 other than assisting in holding rod reduction instrument 100 and bone anchor 102 in fixed relationship to each other.
As discussed previously, rod reduction instrument 100 may be navigated to bone anchor 102 and mounted thereon. Since it is possible that second instrument alignment feature 142 and second bone anchor alignment feature 144 may be out of registration with each other when rod reduction instrument 100 is initially mounted on bone anchor 102, it may be necessary to bring second instrument alignment feature 142 and second bone anchor alignment feature 144 to place alignment locking pin 146 therein. To do so, surgical personnel can rotate rod reduction instrument 100 until second instrument alignment feature 142 registers with second bone anchor alignment feature 144. Alignment locking pin 146 can be inserted into second instrument alignment feature 142 and second bone anchor alignment feature 144. Second instrument alignment feature 142, second bone anchor alignment feature 144, and alignment locking pin 146 can include provisions to releasably hold alignment locking pin 146 in second instrument alignment feature 142 and second bone anchor alignment feature 144. Such provisions can include detents, bayonet members, etc.
In some embodiments, alignment locking pin 146 can include a head or other feature to prevent alignment locking pin 146 from translating through second instrument alignment feature 142 and second bone anchor alignment feature 144. After, spinal stabilization rod 24 is reduced, as discussed herein, alignment locking pin 146 can be removed from second instrument alignment feature 142 and second bone anchor alignment feature 144 to allow rod reduction instrument 100 to be withdrawn from bone anchor 102 (with appropriate actuation of instrument alignment features 110).
With reference now to
With reference now to
At some time, rod reduction instrument 100 can be mounted to bone anchor 102 at step 812. Rod reduction instrument 100 can be rotated to bring instrument alignment features 110 into registration with bone anchor alignment features 111 at step 814. In some embodiments, second instrument alignment features 142 and bone anchor alignment features 144 can be brought into registration at step 814. If desired, alignment locking pin 146 can be inserted into second instrument alignment feature 142 and second bone anchor alignment feature 144 at step 816. Surgical personnel may release instrument alignment feature actuator 108 to cause instrument alignment feature 110 to engage bone anchor alignment features 111 at step 818. Thus, rod reduction instrument 100 can be mounted to bone anchor 102 with instrument threads 118 and bone anchor threads 122 aligned with each other and forming one substantially continuous threaded path along instrument slot 117 and bone anchor slot 120.
Surgical personnel can insert closure member 104 into the distal end of instrument slot 117 at step 820 and begin driving it along instrument slot 117. While closure member 104 is encountering instrument threads 118 of diameter d2 (see
At some time, closure member 104 can be advanced into abutting relationship with spinal stabilization rod 24. Surgical personnel, at step 826, can drive closure member 104 to reduce spinal stabilization rod 24 through a portion of instrument slot 117. In embodiments involving actuator slots 150, method 800 can include reducing spinal stabilization rod 24 through actuator slots 150 at step 828. As spinal stabilization rod 24 is reduced through rod reduction instrument 100, rod reduction instrument 100 and bone anchor 102 can be placed in tension. The tension can arise from the reactions between closure member 104 and spinal stabilization rod 24 as closure member 104 is driven through instrument slot 117 (driving spinal stabilization rod 24 before it). Such tensile forces can cause instrument alignment features of some rod reduction instruments to roll off the edges of corresponding anchor alignment features. Surgical personnel may hold, lock, or otherwise restrain alignment feature actuators 108 to maintain instrument alignment features 110 in engagement with anchor alignment features 111 as spinal stabilization rod 24 is reduced at steps 826 and 828 (and steps 830 and 834).
At some time, leading threads of closure member 104 can encounter bone actuator threads 122 as surgical personnel continue driving closure member 104 toward spinal stabilization rod seat 160 (see
At step 832, surgical personnel can continue driving closure member 104 toward spinal stabilization rod seat 160 thereby reducing spinal stabilization rod 24 through bone anchor slot 120. Spinal stabilization rod 24 can come into abutting relationship with spinal stabilization rod seat 160 thereby becoming seated on spinal stabilization rod seat 160 at step 834. When satisfied with reduction of spinal stabilization rod 24 into bone anchor 102, surgical personnel can withdraw from instrument slot 117 any instrument (such as a screwdriver) which they may have used to drive spinal stabilization rod 24 at step 836. Surgical personnel can remove alignment locking pin 146 from second instrument alignment feature 142 and second bone anchor alignment feature 144 at step 838. Surgical personnel may actuate instrument alignment features 110 thereby causing instrument alignment features 110 to disengage from bone anchor alignment features 111 while translating radially away from the same at step 640. Rod reduction instrument 100 may be withdrawn from bone anchor 102 (and the surgical site if desired) at step 842. In some embodiments, surgical personnel can use rod reduction instrument 100 to reduce rod 24 into additional bone anchors 102 or surgical personnel can reduce additional spinal stabilization rods into other bone anchors 102. When surgical personnel have finished using rod reduction instrument 100 to reduce spinal stabilization rods 24, surgical personnel can withdraw rod reduction instrument 100 from the surgical site and close the same.
With reference to
With reference now to
Instrument resilient fingers 915 can extend from the distal end of instrument body 906 and can be biased against instrument reduced cross sectional portion 923. Instrument reduced cross sectional portion 923 and instrument resilient fingers 915 can be shaped and dimensioned to correspond to each other so that together they generally correspond to the overall cross sectional shape and dimensions of the remainder of instrument body 906.
With reference now to
In
In operation, surgical personnel can navigate instrument 900 to bone anchor 902 as illustrated in
Surgical personnel can push the push-to-lock-push-to-release actuator to actuate instrument body 906 relative to instrument sleeve 908. As the push-to-lock-push-to-release actuator is pushed, instrument 900 can move to the position illustrated by
Since the push-to-lock-push-to-release actuator can lock with instrument 900 in the position illustrated by
In the foregoing specification, specific embodiments have been described with reference to the accompanying drawings. However, as one skilled in the art can appreciate, embodiments of the spinal stabilization rod reduction instrument and bone anchor disclosed herein can be modified or otherwise implemented in many ways without departing from the spirit and scope of the disclosure. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the manner of making and using embodiments of spinal stabilization rod reduction instruments and bone anchors. It is to be understood that the embodiments shown and described herein are to be taken as exemplary. Equivalent elements or materials may be substituted for those illustrated and described herein. Moreover, certain features of the disclosure may be utilized independently of the use of other features, all as would be apparent to one skilled in the art after having the benefit of this description of the disclosure.
