Patent Application
20060058791
The present invention generally relates to devices and surgical methods for treatment of various spinal pathologies. More specifically, the present invention is directed to configurable and anatomically adaptable implantable devices for use in a spine and surgical procedures for altering the biomechanics of a spine, either temporarily or permanently. The devices alter, replace and/or revise existing anatomy and/or previously implanted devices.
Back pain, particularly in the small of the back, or lumbosacral region (L4-S1) of the spine (see,
Through disease or injury, the laminae, spinous process, articular processes, facets and/or facet capsules of one or more vertebral bodies along with one or more intervertebral discs can become damaged which can result in a loss of proper alignment or loss of proper articulation of the vertebra. This damage can result in an anatomical change, loss of mobility, and pain or discomfort. For example, the vertebral facet joints can be damaged by traumatic injury or as a result of disease. Diseases damaging the spine and/or facets include osteoarthritis where the cartilage of joints is gradually worn away and the adjacent bone is remodeled, ankylosing spondylolysis (or rheumatoid arthritis) of the spine which can lead to spinal rigidity, and degenerative spondylolisthesis which results in a forward displacement of the lumbar vertebra on the sacrum. Damage to facet joints of the vertebral body often results in pressure on nerves, commonly referred to as “pinched” nerves, or nerve compression or impingement. The result is pain, misaligned anatomy, a change in biomechanics and a corresponding loss of mobility. Pressure on nerves can also occur without facet joint pathology, e.g., as a result of a herniated disc.
One conventional treatment of facet joint pathblogy is spine stabilization, also known as intervertebral stabilization. Intervertebral stabilization desirably controls, prevents or limits relative motion between the vertebrae, through the use of spinal hardware, removal of some or all of the intervertebral disc, fixation of the facet joints, bone graft/osteo-inductive/osteo-conductive material positioned between the vertebral bodies (with or without concurrent insertion of fusion cages), and/or some combination thereof, resulting in the fixation of (or limiting the motion of) any number of adjacent vertebrae to stabilize and prevent/limit/control relative movement between those treated vertebrae.
Although spine fusion surgery is an efficacious treatment alternative, complications can, nonetheless, result. Patients undergoing spine surgery frequently continue to experience symptoms. For surgical procedures in the lumbar spine, failure rates as high as 37% have been reported after lumbar fusion and 30% for surgery without fusion. See Eichholz, et al., “Complications of Revision Spinal Surgery,” Neurosurg Focus 15(3):1-4 (2003). Post-operative problems can include: decompression related problems, and fusion related problems. Decompression related problems (i.e., loss of normal spine balance resulting in the head and trunk no longer being centered over the pelvis) include, for example, recurrent disc herniation, spinal stenosis, chronic nerve injury, infection, and decompression. Fusion related problems can include, pain from the bone harvest site, failure of a fusion to develop, loosening of the implanted devices, nerve irritation caused by the devices, infection, and poor alignment of the spine.
Stabilization of vertebral bodies can also be achieved (to varying degrees) from a wide variety of procedures, including the insertion of motion limiting devices (such as intervertebral spacers, artificial ligaments and/or dynamic stabilization devices), devices promoting arthrodesis (rod and screw systems, cables, fusion cages, etc.), and complete removal of some or all of a vertebral body from the spinal column (which may be due to extensive bone damage and/or tumorous growth inside the bone) and insertion of a vertebral body replacement (generally anchored into the adjacent upper and lower vertebral bodies). Various devices are known for fixing the spine and/or sacral bone adjacent the vertebra, as well as attaching devices used for fixation, including devices disclosed in: U.S. Pat. Nos. 6,585,769; 6,290,703; 5,782,833; 5,738,585; 6,547,790; 6,638,321; 6,520,963; 6,074,391; 5,569,247; 5,891,145; 6,090,111; 6,451,021; 5,683,392; 5,863,293; 5,964,760; 6,010,503; 6,019,759; 6,540,749; 6,077,262; 6,248,105; 6,524,315; 5,797,911; 5,879,350; 5,885,285; 5,643,263; 6,565,565; 5,725,527; 6,471,705; 6,554,843; 5,575,792; 5,688,274; 5,690,630; 6,022,350; 4,805,602; 5,474,555; 4,611,581; 5,129,900; 5,741,255; 6,132,430; and U.S. Patent Publication No. 2002/0120272.
More recently, various treatments have been proposed and developed as alternatives to spinal fusion. Many of these treatments seek to restore (and/or maintain) some, or all, of the natural motion of the treated spinal unit, and can include intervertebral disc replacement, nucleus replacement, facet joint resurfacing, and facet joint replacement. Such solutions typically include devices that do not substantially impair spinal movement. See, U.S. Pat. Nos. 6,610,091; 6,811,567; 6,902,580; 5,571,171; and Re 36,758; and PCT Publication Nos. WO 01/158563, WO 2004/103228, WO 2005/009301, and WO 2004/103227. Thus, spinal arthroplasty has become an acceptable alternative to fusion, particularly in cases of degenerative disc disease. Arthroplasty devices can be particularly useful because the devices are designed to create an artificial joint or restore the functional integrity and power of a joint.
One device developed to treat patients with, for example, lumbar degenerative disc disease, is the Charité III artificial disc (DePuy Spine, a Johnson & Johnson Company), a device that replaces the natural intervertebral disc 34. Devices, such as the Charité are comprised of suitable orthopedic and biocompatible materials such as cobalt chromium and ultra-high molecular weight polyethylene (UHMWPE). The devices are designed to enable independent translation and rotation, which is a component of physiological motion. See, for example, U.S. Pat. Nos. 6,793,678 and 6,770,095. In other instances, where a disc is removed, e.g. to treat a prolapsed disc, a wedge can be placed within the empty disc space to compensate for the removed natural disc and to support the adjoining vertebral bodies. Further, a plate and screws may be used to hold the wedge in place, such as with an anterior cervical decompression and fusion system.
Once the initial surgical treatment and implantation has been completed for any of these spinal devices (and their related surgical techniques), additional problems and/or complications, such as additional disc problems, future disc degeneration, stenosis, pseudoarthrosis, junctional failure of the spine, failure of the implant and/or additional nerve compression can occur. In some cases, problems can occur much later, even years later. These late onset complications can include, for example, further need for decompression, the onset of other spinal degeneration, requirements for revision of the spinal construct and/or need for fusion of the affected spinal motion segment(s).
Regardless of whether the complications result from decompression or from complications arising after the surgery, revision surgery is sometimes required. Further, in some instances, it may be desirable to convert a spinal pathology that has been treated with, for example, an arthroplasty device that restores motion to the joint to a fusion device that limits motion within the joint. This can particularly be true for patients that have required surgical intervention at an early age.
Part of the invention disclosed herein includes the realization that there exists a need for devices that facilitate revision spinal surgery, desirably with minimal disruption to areas that have already undergone spinal surgery. Needed devices include devices that alter the biomechanics of a joint, either temporarily or permanently, devices that replace and/or repair all or selected portions of an existing device, and devices that address complications or further spinal degeneration that have arisen since the initial surgical intervention.
The invention discloses an implantable arthroplasty device revision system, components of which are configured for implantation in conjunction with an arthroplasty device and a first vertebra and a second vertebra comprising: a spine reconstruction device for replacing bone comprising an elongated tubular member with an anchoring member on a portion of an exterior of the elongated tubular member, and an aperture adapted to communicate with a bone surface; a revision cap adapted to mate with a truncated stem of an implanted arthroplasty device comprising a cap adapted to mate with a stem of the implanted arthroplasty device and an arthroplasty device receiving housing connected to the cap; a revision stem comprising a stem having a cap at an end of the stem and an arthroplasty device receiving housing connected to the cap; a modular cephalad stem having an auxiliary sleeve adapted to receive a threaded female stem, a male stem, and a connector; a cross-linking arm having a length adapted to fit between a pair of cephalad stems, each end of which is adapted to connect to a cephalad arm; and an arthroplasty device joint controller adapted to control movement of an arthroplasty device joint having a base adapted to engage a device joint at a first location, a side and a top adapted to engage the device joint at a second location.
In alternate embodiments of the invention, methods are provided for revising an implanted device for treating a spinal pathology. The methods provide for altering the existing biomechanics of the spine, either permanently or temporarily.
In various embodiments of the invention, a facet joint replacement device is provided for implantation on a vertebral body to replace a portion of the natural facet joint. The implanted device is revised using a securing device of the invention installed on a joint of the facet joint replacement device. The securing cap, or locking cap, prevents and/or limits articulation of the ball and cup joint of the arthroplasty device, converting the device to the equivalent of a spinal fusion device.
In another embodiment of the invention, the implanted articulating joint device is revised by removing portions of the device and replacing the removed portions or components with components of the invention that secure or lock the remaining elements together, achieving an equivalent, or substantial equivalent, of a fusion device's functionality.
The replacement components or devices of the invention are adapted to the pre-existing implanted arthroplasty devices such that some or all of the existing bone anchors do not need to be removed and/or disturbed to convert the articulating arthroplasty device to a device with controlled, limited and/or no movement.
In an embodiment of the invention, the invention includes an implantable device for revising an implanted spinal arthroplasty device comprising: a first surface adapted to communicate with an anatomical surface of the spine; and a second surface adapted to engage a portion of the implanted spinal arthroplasty device. In some embodiments, the first surface is configured to communicate with a revised anatomical surface. In other embodiments, the revision device has threads adapted to engage the anatomical surface at a first end. The threads can be positioned on an exterior surface of the revision device. Additionally, a hollow aperture for receiving a connector of the arthroplasty device can be provided. Where a hollow aperture is provided the aperture can be configured such that it is internally threaded to receive a connector of the arthroplasty device. The revision device can also be adapted to deliver bone cement to the anatomical surface. Additionally, or in the alternative, the revision device can be adapted at an end to engage an arthroplasty device. The devices of the invention can be adapted to alter the biomechanics of the arthroplasty device, either permanently, semi-permanently, or temporarily. In some embodiments, the revision device can be configured to secure the arthroplasty device and/or prevent movement of the arthroplasty device with respect to the anatomical surface(s) to which it is connected.
In an embodiment of the invention, the invention includes an implantable device for altering the biomechanics of an implanted spinal artroplasty device comprising: a first surface adapted to communicate with an anatomical surface; and a second surface adapted to engage a portion of the arthroplasty device. The revision device can also be configured to provide threads to engage the natural anatomical surface at a first end. Threads can be positioned on an interior and/or exterior of the device. The hollow aperture can be configured to receive a connector of the arthroplasty device. In some embodiments, the revision device is adapted to deliver bone cement to the anatomical surface. Additionally, the device can be configured to engage an arthroplasty device and/or alter the biomechanics of the arthroplasty device. Where the biomechanics are altered, such alteration can be made permanently, semi-permanently, or temporarily. The revision device can also be configured to secure the arthroplasty device, to prevent movement of the device with respect to the natural anatomical surface.
In yet another embodiment of the invention, the invention includes an implantable spinal artroplasty device revision system, components of which are configured for implantation in conjunction with a spinal arthroplasty device and a first and second vertebra of a spine, comprising at least one of: a spine reconstruction device for replacing bone comprising an elongated tubular member with an anchoring member on a portion of an exterior of the elongated tubular member, an aperture adapted to communicate with a bone surface, and a proximal end adapted to replace a mating surface; a revision cap adapted to mate with a truncated stem of an implanted arthroplasty device comprising a cap adapted to mate with a stem of the implanted arthroplasty device and an arthroplasty device receiving housing connected to the cap; a revision stem comprising a stem adapted to be implanted within bone and having a cap at an end of the stem and an arthroplasty device receiving housing connected to the cap; a modular cephalad stem having an auxiliary sleeve adapted to receive a threaded female stem, a male stem, and a connector; a cross-linking arm having a length adapted to fit between a pair of cephalad arms of an arthroplasty device, each end of which is adapted to connect to a cephalad arm; and an arthroplasty device joint controller adapted to control movement of an arthroplasty device joint having a base adapted to engage a device joint at a first location, a side and a top adapted to engage the device joint at a second location. Embodiments of the invention can also include an artificial disc, intervertebral wedges, bone filler, bone cement, and biocompatible adhesive. Additionally, in some embodiments, the restoration units can be internally and/or externally threaded. The restoration unit(s) can be configured such that it is adapted to replace a spine anatomy, such as pedicle, lamina, spinous processes, other processes and/or the vertebral body. The restoration units are adapted to connect to an arthroplasty device. Thus, in at least some embodiments, the arthroplasty device receiving housing is positioned adjacent the cap and/or the housing is adapted to connect to an element of an implanted arthroplasty device. In some embodiments, the revision cap is a polyaxial element. Further embodiments can include a configuration wherein the housing moves relative to the cap by a ball and socket connector. The housing can be rotatably connected to the revision cap. The revision cap can be adapted to engage the implanted arthroplasty device. In some embodiments it may be desirable to provide for internal and/or external threading of the sleeve. A female aperture forming a keyway can also be provided. Additionally, the male stem can be configured to have a male protrusion adapted to fit within a configured female aperture of the auxiliary sleeve. The modular cephalad stem can be adapted in some embodiments to provide anti-rotation of the male stem to the female auxiliary sleeve. Further, the modular stem can include a securing member. The base of the joint controller can be positioned on the arthroplasty device joint opposite a position of the top of the joint controller. The revision system can also be configured so that the joint controller snap fits over the joint of the arthroplasty device. In other embodiments, the joint controller has an aperture on the top of the device, which can further be adapted to receive a securing mechanism.
In yet another embodiment of the invention, an implantable device for restoring a target surface area of a vertebral body, the implantable device comprising an elongated tubular member with an anchoring member on a portion of an exterior of the elongated tubular member at a first end, and an aperture adapted to communicate with a tissue and an aperture adapted to communicate with an implantable arthroplasty device at a second end.
In yet another embodiment of the invention, an implantable device is provided for revising a previously implanted arthroplasty device having a fixation element, the implantable device comprising a cap adapted to mate with a stem of the previously implanted fixation element, and a housing connected to the cap on a first end and adapted to engage an element of an arthroplasty device on a second end.
Another embodiment of the invention includes an implantable device for use with an arthroplasty device, the implantable device comprising a stem having a tapered first end, and a housing adapted to engage an element of the arthroplasty device at a second end.
Yet another embodiment of the invention provides an implantable device for use with an arthroplasty device, the implantable device comprising a modular stem having a first stem component with a male end, and a second stem component with a female end, wherein the male end is adapted to fit within the female end to prevent rotation and/or relative movement.
In still another embodiment, an implantable device for use with an arthroplasty device, the implantable device comprising a cross-linking arm adapted to connect to a first arm of the arthroplasty device at a first end and a second arm of the joint arthroplasty device at a second end is provided.
In yet another embodiment of the invention, an implantable device for use with an arthroplasty device comprising a lock adapted to engage a joint of the arthroplasty device to reduce, control, modify and/or prevent articulation of the joint.
Embodiments of the invention can also be practiced according to a method of revising an implanted arthroplasty device, the method comprising: accessing an implanted spinal arthroplasty device; and inserting a revision device adapted to alter the biomechanics of the implanted spinal arthroplasty device. Where methods are employed, the revision device can be configured to restore the operation of the implanted arthroplasty device. Alternatively, or additionally, the revision can device can be configured to limit and/or modify the operation of the implanted arthroplasty device. In practicing the method of the invention, the implanted arthroplasty device can be converted to a fusion device. Revision can be achieved at the time of implantation of the arthroplasty device or at a subsequent time. When performing the methods of the invention, a user will select, as many times as desirable, from a plurality of devices suitable for revising the arthroplasty device.
All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
FIGS. 23 illustrates a caudal cup incorporating a flange and a compression device to control movement of the cross-member of an arthroplasty device;
The invention relates generally to implantable devices, apparatus or mechanisms that are suitable for implantation within a human body to restore, augment, and/or replace soft tissue and connective tissue, including bone and cartilage, and systems for treating spinal pathologies. In some instances the implantable devices can include devices designed to replace missing, removed or resected body parts or structure. The implantable devices, apparatus or mechanisms are configured such that the devices can be formed from parts, elements or components which alone or in combination comprise the device. The implantable devices can also be configured such that one or more elements or components are formed integrally to achieve a desired physiological, operational or functional result such that the components complete the device. Functional results can include the surgical restoration and functional power of a joint, controlling, limiting or altering the functional power of a joint, and/or eliminating the functional power of a joint by preventing joint motion. Portions of the device can be configured to replace or augment existing anatomy and/or implanted devices, and/or be used in combination with resection or removal of existing anatomical structure.
The devices of the invention are designed to interact with the human spinal column 10, as shown in
Two transverse processes 24, 24′ thrust out laterally, one on each side, from the junction of the pedicle 16 with the lamina 20. The transverse processes 24, 24′ serve as levers for the attachment of muscles to the vertebrae 12. Four articular processes, two superior 26, 26′ and two inferior 28, 28′, also rise from the junctions of the pedicles 16 and the laminae 20. The superior articular processes 26, 26′ are sharp oval plates of bone rising upward on each side of the vertebrae, while the inferior processes 28, 28′ are oval plates of bone that jut downward on each side. See also
The superior and inferior articular processes 26 and 28 each have a natural bony structure known as a facet. The superior articular facet 30 faces medially upward, while the inferior articular facet 31 (see
As discussed, the facet joint 32 is comprised of a superior facet and an inferior facet (shown in
An intervertebral disc 34 located between each adjacent vertebra 12 (with stacked vertebral bodies shown as 14, 15 in
Thus, overall the spine comprises a series of functional spinal units that area motion segment consisting of two adjacent vertebral bodies, the intervertebral disc, associated ligaments, and facet joints. See Posner, I, et al. “A biomechanical analysis of the clinical stability of the lumbar and lumbosacral spine.” Spine 7:374-389 (1982).
As previously described, a natural facet joint, such as facet joint 32 (
When the processes on one side of a vertebral body 14 are spaced differently from processes on the other side of the same vertebral body, components of the devices on each side would desirably be of differing sizes as well to account for anatomical difference that can occur between patients. Moreover, it can be difficult for a surgeon to determine the precise size and/or shape necessary for an implantable device until the surgical site has actually been prepared for receiving the device. In such case, the surgeon typically can quickly deploy a family of devices possessing differing sizes and/or shapes during the surgery. Thus, embodiments of the spinal devices of the present invention include modular designs that are either or both configurable and adaptable. Additionally, the various embodiments disclosed herein may also be formed into a “kit” or system of modular components that can be assembled in situ to create a patient specific solution. As will be appreciated by those of skill in the art, as imaging technology improves, and mechanisms for interpreting the images (e.g., software tools) improve, patient specific designs employing these concepts may be configured or manufactured prior to the surgery. Thus, it is within the scope of the invention to provide for patient specific devices with integrally formed components that are pre-configured.
A configurable modular device design, such as the one enabled by this invention, allows for individual components to be selected from a range of different sizes and utilized within a modular device. One example of size is to provide caudal and cephalad stems of various lengths. A modular implantable device design allows for individual components to be selected for different functional characteristics as well. One example of function is to provide stems having different surface features and/or textures to provide anti-rotation capability. Other examples of the configurability of modular implantable device of the present invention as described in greater detail below.
Implantable devices of the present invention are configurable such that the resulting implantable spinal device is selected and positioned to conform to a specific anatomy or desired surgical outcome. The adaptable aspects of embodiments of the present invention provide the surgeon with customization options during the implantation or revision procedure. It is the adaptability of the present device systems that also provides adjustment of the components during the implantation procedure to ensure optimal conformity to the desired anatomical orientation or surgical outcome. An adaptable modular device of the present invention allows for the adjustment of various component-to-component relationships. One example of a component-to-component relationship is the rotational angular relationship between a crossbar mount and the crossbar. Other examples of the adaptability of modular device of the present invention as described in greater detail below. Configurability may be thought of as the selection of a particular size of component that together with other component size selections results in a “custom fit” implantable device. Adaptability then can refer to the implantation and adjustment of the individual components within a range of positions in such a way as to fine tune the “custom fit” devices for an individual patient. The net result is that embodiments of the modular, configurable, adaptable spinal device and systems of the present invention allow the surgeon to alter the size, orientation, and relationship between the various components of the device to fit the particular needs of a patient during the actual surgical procedure.
In order to understand the configurability, adaptability and operational aspects of the invention, it is helpful to understand the anatomical references of the body 50 with respect to which the position and operation of the devices, and components thereof, are described. There are three anatomical planes generally used in anatomy to describe the human body and structure within the human body: the axial plane 52, the sagittal plane 54 and the coronal plane 56 (see
Turning now to
The arthroplasiy device 100 and the various revision devices disclosed herein can be formed of a variety of materials. For example, where the devices have bearing surfaces (i.e. surfaces that contact another surface), the surfaces may be formed from biocompatible metals such as cobalt chromium steel, surgical steel, titanium, titanium alloys, tantalum, tantalum alloys, aluminum, etc. Suitable ceramics and other suitable biocompatible materials known in the art can also be used. Suitable polymers include polyesters, aromatic esters such as polyalkylene terephthalates, polyamides, polyalkenes, poly(vinyl) fluoride, PTFE, polyarylethyl ketone, and other materials that would be known to those of skill in the art. Various alternative embodiments of the spinal arthroplasty device could comprise a flexible polymer section (such as a biocompatible polymer) that is rigidly or semi rigidly fixed to the adjacent vertebral bodies whereby the polymer flexes or articulates to allow the vertebral bodies to articulate relative to one another.
The spinal arthroplasty device 100 includes a crossbar 105, a pair of cephalad arms 120, 120′ and a pair of caudal arms 150, 150′. In this exemplary embodiment the facets of the spine (see
The crossbar 105 has a first end 110 and a second end 115. In the illustrated embodiment the crossbar 105 is a two piece bar where the first end 110 is attached to a threaded male portion having threads. The crossbar second end 115 is attached to a threaded female portion sized to receive the threads. The threaded ends allow for the width of the crossbar to be adjusted to mate with the width between caudal bearings 150. Additional alternative embodiments of the crossbar 105 could include a series of solid crossbars of varying widths and/or thicknesses, or an adjustable crossbar having some form of locking or biasing mechanism (such as a spring-loaded tensioner or detent mechanism, etc.).
A pair of cephalad arms 120, 120′ are also illustrated in the exemplary embodiment of the configurable and adaptable spinal arthroplasty device 100 of the present invention. Each cephalad arm 120, 120′ includes a bone engaging end 125, 125′ and an end 140 adapted to couple to the crossbar 105. The cephalad end 140 is adapted to engage the crossbar 105 and includes an arm 145 and an elbow 147. The cephalad end 140 is attached to the crossbar using the crossbar mount 175. The bone engaging end 125 includes a cephalad stem 130 and a distal tip 135. The cephalad stem 130 and the distal tip 135 are threaded or otherwise configured to engage. Alternatively, the distal tip 135 could be formed integrally with the cephalad stem 130, of the same or a different material as the cephalad stem 130. In the illustrated embodiment of the cephalad stem 130, surface features 132 are provided. Surface features 132 can be, for example, a textured surface or other surface such as, for example, surface features to assist in bony in-growth. Similarly, the illustrated embodiment of the distal tip 135 can have surface features 137.
The crossbar mount 175 is a connection structure to couple the cephalad arms 120, 120′ to the crossbar 105. In the illustrated embodiment, the crossbar mount 175 includes a cephalad arm engaging portion 172, a crossbar engaging portion 174 and a fixation element 176. Fixation element can be a screw, stem, cork-screw, wire, staple, adhesive, bone, and other material suitably adapted for the design. As will be described in greater detail below, embodiments of the crossbar mount 175 provide adaptability between the cephalad elements 120 and the crossbar 105 and the loading characteristics of the crossbar ends 110, 115 and the caudal cups 150, 150′.
Another implantable arthroplasty device 200 is illustrated in
The cephalad structure 210 and the caudal structure 220 illustrated in
Turning now to
As shown in
Turning now to
c illustrates a device 400 implanted into a vertebral body 12 such that the cap of the device can function as a pedicle replacement. In this illustration, there is no preexisting stem or other device, and device 400 therefore includes an integral stem 165. The device 400 can be implanted such that the device (desirably and generally) does not intersect the central sagittal axis 411 of the vertebral body. The housing and cap can be configured to provide a fixed structure, or can be configured to enable the housing and cap to be engaged such that rotation between the two elements is enabled.
Turning now to
As shown in
The prongs 522, 522′ engage a wall 526 of the securing device on one side. The wall 526 mates with a top or roof 528 that fits above the cross-bar member. The top 528 has an aperture 529. The aperture 529 can function as a detent, catch or plunger to snap fit over the ball end 110 of the crossbar member in an arthroplasty device. Alternatively, the securing device can be a securing mechanism, such as a set screw 530.
Thus, the implanted arthroplasty device can be revised to incorporate locks or “fusion caps” that desirably convert the device from an articulating joint replacement construct to a non-articulating (or controlled and/or limited articulation) spinal fusion construct. In this embodiment, the fusion cap can be installed on or into the caudal cups to desirably immobilize the cephalad bearings within the cups. In various embodiments, the fusion caps could immobilize the cephalad bearings by direct compression or contact, through use of a set screw or other device to secure the cephalad bearing relative to the cup, or the fusion cap could contain or cover an encapsulating material, such as bone cement, which could fill the caudal cup and immobilize the cephalad bearing. Various techniques could be used in conjunction with the installation of such fusion caps, and the cap could be installed prior to, during, or after the completion of a concurrent spinal fusion procedure, including the removal of intervertebral disc material, installation of fusion cages, and/or introduction of material (such as bone graft material) that desirably promotes spinal fision. Alternative embodiments could incorporate bearings of different shapes or sizes (not shown), including square or non-spherical bearings and/or bearings shaped to that fit snugly into and accommodate most or all of the interior of the caudal cup (not shown), that can be secured within the cup in a similar manner.
Turning now to
Additional modifications of the caudal cup of an arthroplasty device are also possible in order to improve the operation and reliability of the arthroplasty device through the range of spinal motion. Further, these modifications can change the operation of the device from one enabling a full range of motion, to a device that enables less than a full range of motion, or to a device that restricts range of motion (this “restriction” could extend from allowing full motion to allowing partial or controlled motion to allowing no motion—thus functionally achieving some of all of the effects of a fusion device). One such modification is illustrated in
In alternative embodiments, such as that shown in
In one alternate embodiment, once the cephalad and caudal components of the device has been secured to the targeted vertebral bodies, one or more elastic compression devices or “bands” 740 could be secured about the caudal cups and bearing elements (see
In another alternate embodiment, the compression device could comprise an elastic or pliable material, which may or may not be surrounded by a non-elastic housing, whereby the elastic material allows various movement of the bearing surfaces (with resistance commensurate to the flexibility of the material, as well as flexibility allowed by the coupling to the device components), but the optional non-elastic housing acts as an ultimate “stop” to movement of the bearing surfaces relative to the caudal cup. Such embodiments could include one or more “encapsulated” bearing surfaces, such as shown in FIGS. 24C-D, which show two caudal cup and cephalad bearing pairs (of a facet replacement device), each pair surrounded by a flexible skin or “jacket” 740 which permits relative movement between the cup and bearing, but which desirably encapsulates or isolates the cup and bearing pair from the surrounding environment (totally or partially or some combination thereof). In practice, the jacket 740 can serve many functions, including (but not limited to) (1) as a shock absorber or brake to slow, control, modify and/or limit movement of the bearing/cup complex throughout and/or at the extreme ranges of motion, (2) as a stop or limiter to reduce and/or prevent complete or partial dislocation of the joint, (3) as a barrier to prevent surrounding tissues from invading the bearing surfaces and/or being “pinched” or damaged between moving surfaces, and (4) as a barrier or “filter” to prevent “bearing wear particulate,” or other bearing by-products, from reaching and impacting surrounding tissues (or to contain fluids or other materials including, but not limited to, joint lubricating fluids, antibiotics and/or fluids that provide a biological marker and/or indicator—including bioreactive materials—upon rupture or compromise of the barrier). In a similar manner, the jacket 740 could encompass the entire bearing construct, with only the cephalad and caudal stems (and possibly the crossbar, depending upon whether the jacket encompasses one or both bearing constructs) protruding through the jacket and extending into the vertebral bodies. Depending upon the type of polymer (or other material) used, as well as the physical properties and orientation of the polymer, the jacket 740 could be designed to control the motion of the device in a desired manner, and could also control the movement of the device to more accurately replicate the natural motion of the spinal segment. For instance, a polymer jacket could be designed to allow a greater degree of freedom in flexion/extension, but limit (to some extent) the degree of lateral bending or torsion of the same segment, by proper choice and orientation of the polymer or other material. In one alternative embodiment, the band could comprise a flexible, polymeric (including, but not limited to, biocompatible polymeric) material.
In various alternative embodiments, the physical properties of the materials used could be selected based on an ability to alter over time or in response to one or more biological, environmental, temperature and/or externally induced factors, altering the properties of the material (i.e., polymers, ceramics, metals—Nitinol—etc.). For example, the material could comprise a material that hardens over time (or in the presence of body fluids, proteins, or body heat, etc.), which initially allows the components to freely articulate at the time of implantation (and thus minimize the stresses experienced by the anchoring components), but which hardens and subsequently resists movement to a greater degree once the component anchoring has solidified or bonded to the surrounding bone. Biodegradable materials can be used in embodiments to adapt an implanted device to achieve a temporary fixation of the device. By preventing movement for a period of time, healing can be facilitated, among other things. Once a suitable amount of time has passed and the biodegradable material (or other types of materials) degrades (or otherwise alters its material properties in some manner), the device will then return to its initial state of biomechanical movement. Where the material alteration is induced by externally induced factors (such as directed radiation, rf and/or sonic energy), the external factor could desirably alter the physical properties of the material(s) in a partially or completely reversible manner (depending upon the type, duration, frequency and/or amplitude of the induced factor), allowing for controlled alteration of the material properties in a minimally-invasive and/or completely non-invasive manner.
Similarly, the “band” could comprise an elastic, non-elastic or rigid material, such as stainless steel cable, which desirably prevents relative motion of the device components beyond a certain pre-defined maximum extension, flexion, rotation and/or torsion. In various embodiments, the band could alternatively be installed to limit motion of the device to prevent dislocation, or to minimize or control the articulation of the device to some degree (such as to protect a disc replacement device against unwanted motion in one or more directions, protect an adjacent fused level against unwanted stresses, or to protect various tissues from experiencing stresses and/or damage). If desired, the cable could be tightened or loosened post-surgery, in a minimally-invasive manner, to alter performance of the device.
Where the revision involves a spinal level incorporating an artificial disc replacement, the revision instrumentation could include wedges or “shims” that could be used to immobilize the artificial disc (thereby augmenting the motion modification provided by the revision component) and/or further increase the likelihood of achieving a successful fusion in combination with the revision constructs described herein.
Once the incision is made the implanted arthroplasty device is accessed 802. Unless, the biomechanics have been assessed prior to surgical access and a device has been preselected, the surgeon can then select a revision device 804, e.g. from a kit, that is adapted to alter the biomechanics or revise the arthroplasty device. Whether selected in advance of surgery, or during the surgical procedure, the surgeon next inserts the revision device 806. As discussed above, the revision device can be one that alters the biomechanics, whether temporarily or permanently, or otherwise revises the implanted arthroplasty device. The step of selecting a revision device and implanting a revision device can be repeated as often as required to achieve the desired result. Once the surgeon is satisfied that the desired result is achieved, the incision is closed 808.
While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.
This application is a continuation-in-part of commonly assigned U.S. patent application Ser. No. 11/071,541 to Kuiper et al., filed Mar. 2, 2005, and also claims the benefit of U.S. Provisional Patent Application Ser. Nos. 60/643,556 to Reiley filed Jan. 13, 2005, and 60/602,827 to McLeer filed Aug. 18, 2004, the disclosures of which are both incorporated herein.
| Number | Date | Country | |
|---|---|---|---|
| 60643556 | Jan 2005 | US | |
| 60602827 | Aug 2004 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11071541 | Mar 2005 | US |
| Child | 11206676 | Aug 2005 | US |
