Abstract:
An adjustable spinal implant ( 10 ) is provided for use in connecting elongate members ( 12 ) as well as vertebral spacers such as corpectomy devices, intervertebral fusion devices, and other prostheses. The implant ( 10 ) may have fittings ( 80 ) on either end comprising fixed ( 100 ) or articulating ( 200 ) jaws, endplates, or other engagement structures. The implant ( 10 ) comprises a housing ( 40 ) with an internal rotor ( 60 ); an extending shaft ( 20 ); and a locking collar (70). The extending shaft ( 20 ) has an external helical groove ( 23 ) that meshes with an internal helical groove ( 63 ) on rotor ( 20 ). Length adjustment occurs by transforming axial movement of the extending shaft ( 20 ) into a rotary movement of the rotor ( 60 ) via helical engagement. The locking collar ( 70 ) comprises protrusion ( 73 ) engaging grooves ( 63 ) of rotor ( 60 ), thus providing a simple, positive locking mechanism without requiring the surgeon to apply excessive force to lock the length.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to a device for spinal fixation, and in particular to an adjustment device for many types of spinal implants. The device finds particularly suitable applications in spinal fusion devices such as a connector for coupling elongate members (such as spinal rods), plates, and the like, as well as in adjustable vertebral spacers for intervertebral fusion devices, corpectomy devices, and other vertebral prostheses.  
         [0003]     2. Background  
         [0004]     The spinal column is a complex system of bones in stacked relation held upright by fibrous bands called ligaments and contractile elements called muscles. This column is critical for protecting the delicate spinal cord and nerves and for providing structural support for the entire body. There are seven bones in the neck (cervical) region, twelve bones in the chest (thoracic) region, and five bones in the low back (lumbar) region. There are also five bones in the pelvic (sacral) region which are normally fused together and form the back part of the pelvis. Each vertebra has a roughly cylindrical body with wing-like projections and a bony arch. The arches, which are positioned next to one another, create a tunnel-like space which houses the spinal cord. The anterior cylindrical bodies of the vertebrae, which are spaced apart by intervertebral discs, bear most of the compressive load of the spinal column. The spinal column is also flexible and is capable of a high degree of curvature and twist through a wide range of motion.  
         [0005]     It is often necessary to surgically treat spinal disorders, such as scoliosis, as well as to surgically correct spinal problems such as those that occur due to trauma, developmental irregularities, or disease. Numerous systems are known for use in spinal correction and fixation, depending on the type of problem sought to be solved.  
         [0006]     Spinal fusion (arthrodesis) devices attempt to restore stability to the spine by fusion in the problem area. These systems generally employ spinal instrumentation having connective structures such as one or more plates or rods that are placed on portions of the spinal column near the area intended to be fused. These systems usually include attachment devices including, but not limited to, pedicle screws, transverse process hooks, sublaminar hooks, pedicle hooks, and other similar devices. Rod systems, of which there are several, are frequently used in spine stabilization. Typically, the rods are utilized in pairs longitudinally along the length of the spinal column. For the sake of simplicity, the term “rod” will be used throughout to refer to any elongate or longitudinal member.  
         [0007]     It is known that the strength and stability of a dual rod assembly can be increased by coupling the two rods with a cross-brace or connector that extends substantially perpendicular to the longitudinal axes of the rods across the spine. The simplest situation in which a connector could be used occurs when the two rods are geometrically aligned. Specifically, the two rods are parallel to each other, that is, there is no rod convergence or divergence in the medial-lateral direction. Stated alternatively, the two rods have the same orientation with respect to the coronal plane (viewed in the anterior-posterior direction); or, the rods are coplanar from a lateral view; and the two rods are located a uniform distance from each other.  
         [0008]     In reality, spinal rods are rarely geometrically aligned in the above-mentioned simplest situation. The actual variations of geometrical alignment must be accommodated in some fashion. One way to accommodate actual arrangement is for one or both of the rods to be bent to accommodate the connector. However, any bending in either of the rods can adversely affect the fixation to the spine and compromise clinical outcome. Furthermore, the bending can adversely affect the mechanical properties of the rods, not to mention the fact that bending is both difficult and time-consuming for the surgeon. The connector can also be bent so that the disturbance to the rod positioning is minimized. Unfortunately, this too can cause the mechanical properties of the connector to be compromised.  
         [0009]     To remedy these concerns, connectors with some adjustability have been designed to adapt for variations from the simplest geometrical alignment. One major problem with current devices is that those that do provide some form of length adjustability utilize inferior locking designs. Some utilize a slideable member with a pin anchor. Others use a slideable member with a compression style lock. The former style is cumbersome and runs the risk of pin-removal. The latter style is cumbersome and provides inadequate locking strength. In fact, most require the surgeon to impart a large amount of force on the construct in order to engage the lock. Despite engagement of these locking devices, none of these types of locking devices has been shown to adequately positively lock the length.  
         [0010]     Another major problem with the current devices is that the method of locking the rod to the connector is inefficient or inadequate. Many current devices utilize threaded set screws that engage an exterior surface of the rod. Threading the set screw into the set screw opening applies a compressive force on the rod, which is supposed to secure the rod. Several problems exist with these threaded connections, including cross-threading, loosening over time, and the structural deformities imposed on the surface of the rod that is contacted by the set screw. Another current device uses a clamp body having opposable arms and utilizes a cam lug to force the arms closed in a scissors-like action to compressively load the rod. Yet another device utilizes a yoke-like clamping body disposed in a through-bore having resilient sidewalls that provide a wedging effect on the rod upon tightening of a locking screw in the through-bore. None of these devices, however, provide the simple, secure locking fit desired to positively retain a rod in situ long term.  
         [0011]     An additional problem with these types of devices is that they are typically multi-piece systems that can be difficult to assemble and use in the surgical environment. And, even those that are one-piece designs do not allow for adjustments to compensate for all three modes in which there may be variation from geometrical alignment: convergence or divergence in the medial-lateral plane, non-coplanar rods, and variability in rod separation distances. For example, U.S. Pat. No. 5,947,966 discloses a device for linking adjacent spinal rods. In one embodiment, the device includes two members that are movable with respect to one another to accommodate different rod separation distances. A pin on one member engages a groove on the other member to provisionally couple the two members, thereby preventing a surgeon from separating the two members. Because the pin is sized to exactly fit the groove, no movement of the pin transverse to the longitudinal axis of the groove is possible. As a result, the device disclosed in the &#39;966 patent cannot accommodate non-coplanar rods or adjust for rod convergence or divergence.  
         [0012]     In some spinal surgeries, different types of devices are used to maintain the normal spacing between vertebrae, as well as to alleviate compression of the spinal cord. These devices are known as corpectomy devices and are typically inserted into a cavity created when all or a portion of one or more vertebrae are removed. One example of corpectomy devices are hollow mesh cages filled with bone chips or marrow, or even artificial bone material. Limitations of most present-day intervertebral implants are significant and revolve largely around the marked variation in disc space shape and height that results from either biologic variability or pathologic change. For example, if a disc space is 20 mm in height, a cylindrical implant bridging this gap requires a minimum height of 20 mm just to contact the end plate of the vertebral bone. Generally, end plate disruption must occur to allow a generous bony union, meaning that an additional 2-3 mm must be added on each end, resulting in a final implant size of 24-26 mm. During implantation from an anterior approach, excessive retraction is often required on the great blood vessels which significantly enhances the risk of devastating complications such as vascular tears or thrombosis. On the other hand, during a posterior approach, large implants may require excessive traction on neural elements for adequate placement, even if all posterior bony elements are removed. In some instances, an adequate implant size cannot be inserted posteriorly, particularly if there is a significant degree of ligamentous laxity requiring higher degrees of distraction to obtain stability by tightening the annular ligamentous tension band. Compromising on implant size risks sub-optimal stability or a loose implant, which has a greater chance for migration within or expulsion from the disc space. The alternative of excessively retracting neural elements to facilitate a posterior implant application results in a neuropraxia at best and permanent neural damage at worst.  
         [0013]     Thus the need exists for an adjustable corpectomy that is simple to use in clinical procedures and that adequately and effectively spans the distance between vertebral bodies, is easily adjustable to account for space variability, and provides a secure lock once the desired dimension is achieved. Additionally, the need exists for an improved connector for spinal rods that can allow adjustability in all geometrical arrangements; that can provide quick and secure locking of the rod; and that provides a simple, positive locking length-adjusting mechanism that does not rely on compression fit or pin locking mechanisms.  
       BRIEF SUMMARY OF THE INVENTION  
       [0014]     The present invention generally relates to devices for spinal fixation, and in particular to adjustable devices for use as connectors for coupling spinal rods or other elongate members; as well as for use as corpectomy devices and the like. Various embodiments are discussed, with the primary invention being utilized in different types of implants. As used herein, the general term “connector” shall refer to the device in its many embodiments, regardless whether the device is being used to connect elongate members (as in spinal rod systems) or to span the distance between two vertebral bodies (as in corpectomy devices). The connector generally comprises a two-piece body having an extending shaft and a housing; a rotor; and a locking collar. The terminal ends of each connector may be fitted with a fixed rod-receiving jaw, an articulating rod-receiving jaw, or simply with endplates or other structures of various designs having bone receiving surfaces thereon.  
         [0015]     In a first embodiment the extending shaft has an external surface containing thereon a helical profile. The rotor likewise has an internal surface containing thereon one or more helical surfaces that correspond to the external surface of the extending shaft. The internal helical surface of the rotor is placed in intimate contact with the external helical surface of an extending shaft. This intimate contact couples the rotor to the extending shaft such that translational movement of the extending shaft results in rotation of the rotor, and vice versa. Similarly, preventing movement of either the extending shaft or the rotor automatically prevents movement of the other.  
         [0016]     The rotor is a substantially cylindrical body that has axial grooves disposed about its circumference. The locking collar is also a substantially cylindrical member having at least one protrusion disposed radially on the internal surface thereof. When the extending shaft is translated into or out of the body, the helical surface causes the rotor to spin inside the housing. When the desired length of the connector is achieved, the locking collar is moved from its unlocked position to its locked position, wherein the at least one protrusion engages the grooves on the rotor&#39;s circumference. Once a protrusion is inside a groove, rotational movement of the rotor is prevented, which thereby prevents axial movement of the extending shaft. This provides a positive lock for the extending shaft (and therefore for the length of the connector) without the need for a compression fit and without requiring the surgeon to impart large forces onto the construct.  
         [0017]     In another aspect of the invention, a unique locking cam is provided at each jaw to secure a rod to the connector. The locking cam generally comprises a substantially cylindrical body having an engaging end and a driving end. The engaging end has a combination concave surface having differing curvatures disposed about its circumference, or simply having curvatures disposed at different points on the surface. The driving end has a cavity to receive a driving instrument and an appurtenant stop disposed at a location along its perimeter. The jaw comprises an opening to receive the locking cam therein. The opening is preferably substantially cylindrical having a discontinuity disposed out of phase with the appurtenant stop. Upon insertion of the cam into the opening, the driving instrument turns the cam the desired amount (preferably 180 degrees). This turning rotates the engaging end about the cam&#39;s axis of rotation, which brings the cam into tighter engagement with the rod as the combination curvatures rotate into engagement with the outer surface of the rod. Once the cam is fully turned, the stop engages the discontinuity, which visually and tacitly informs the surgeon that the cam is locked.  
         [0018]     In another aspect of the invention, an articulating jaw is provided. The articulating jaw itself comprises a jaw with a locking cam on one end and a ball-shaped protrusion on the other end. The terminal end of the connector comprises a substantially cylindrical member having an axial opening therein and comprising axial fingers for receiving the ball of an articulating jaw. The axial fingers are deflectable inwardly by a locking collar. The locking collar is disposed about the external surface of the fingers and is slideable between a first unlocked position and a second locked position. In the second position, the articulating jaw locking collar imparts a radial compressive force on the surface of the ball, thereby locking it into position. This can be achieved in various ways, including shaping the external surface of the fingers with an increasing diameter toward the distal ends thereof, such that as the articulating jaw locking collar moves distally, it rides along the increasing diameter, thus forcing the internal surface into compressive contact with the ball. Additionally the articulating locking collar itself may be fitted with an inner surface that has an increasing diameter in the locked direction. Many other structural combinations are possible to achieve this effect, the end result being to lock the ball in a given orientation. The articulating jaw can therefore assume any number of angles to better facilitate the rod.  
         [0019]     The articulating jaw therefore forms a ball and socket joint that enables movement to allow the connector to join rods that are not parallel. Alternatively, the ball-shaped protrusion may be fitted on the body of the connector and the jaw may have the corresponding socket to provide the ball and socket union.  
         [0020]     In another aspect of the invention, a fixed length connector is provided. The connector comprises a solid shaft with jaws on either end. The shaft is made from titanium or any material suitable for implantation. The jaws maybe of the fixed or articulating variety as described.  
         [0021]     In another embodiment of the invention the jaws comprise endplates or other structures to be used to engage vertebral bodies or other bony structures. The endplates can be fixed or variable to allow for better anatomical fit.  
         [0022]     Alternative embodiments are also depicted utilizing pre-bent connectors; connectors utilizing multiple articulating jaws; connectors using grooved extending shafts; connectors using helical ratcheting shafts; connectors using a taper lock; and connectors utilizing a pivoting body.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:  
         [0024]      FIG. 1  is a perspective view of the apparatus according to one embodiment showing two connectors of the invention being used to connect two surgical rods secured to multiple bone anchors;  
         [0025]      FIG. 2  is a close-up perspective of a connector according to one embodiment wherein the connector further comprises an articulating jaw that is securing two non-parallel surgical rods;  
         [0026]      FIG. 3  is a perspective view of a connector according to an embodiment of the invention having one fixed jaw and one articulating jaw;  
         [0027]      FIG. 4  is a top plan view of the connector shown in  FIG. 3 ;  
         [0028]      FIG. 5  is a side elevation view of the connector shown in  FIG. 3 ;  
         [0029]      FIG. 6  is a section view in perspective of the connector according to an embodiment of the invention having a fixed jaw and an articulating jaw;  
         [0030]      FIG. 7  is a perspective view of the two-piece body of a connector according to an embodiment of the invention;  
         [0031]      FIG. 8  is a section view of the connector shown in  FIG. 7 ;  
         [0032]      FIG. 9  is a side elevation view of the connector shown in  FIG. 7 ;  
         [0033]      FIG. 10  is an end view of the connector shown in  FIG. 7  looking into the second axial opening;  
         [0034]      FIG. 11  is a perspective view of a rotor according to an embodiment of the invention;  
         [0035]      FIG. 12  is a side elevation view of the rotor shown in  FIG. 11 ;  
         [0036]      FIG. 13  is an end view of the rotor shown in  FIG. 11 ;  
         [0037]      FIG. 14  is a side elevation view in section of the rotor shown in  FIG. 11 ;  
         [0038]      FIG. 15  is a sectional elevation view of a connector according to the invention having a fixed jaw (shown with a rod in the jaw and the cam in a locked position) and an articulating jaw (shown with the rod in the jaw and the cam in an unlocked position);  
         [0039]      FIG. 16  is a perspective view of a locking collar according to an embodiment of the invention;  
         [0040]      FIG. 17  is an end view of the locking collar shown in  FIG. 16 ;  
         [0041]      FIG. 18  is a side elevation view of the locking collar shown in  FIG. 16 ;  
         [0042]      FIG. 19  is a top plan view of the connector shown in  FIG. 2 ;  
         [0043]      FIG. 20  is a partial top plan view of an articulating jaw of a connector according to one embodiment of the invention showing the locking cam in a locked positions and the articulating jaw in an unlocked position;  
         [0044]      FIG. 21  is partial top plan view of the articulating jaw shown in  FIG. 20  showing the locking cam in an unlocked position and the articulating jaw in a locked position;  
         [0045]      FIG. 22  is a perspective view of a locking cam according to an embodiment of the invention;  
         [0046]      FIG. 23  is a driving end axial view of the locking cam of  FIG. 22 ;  
         [0047]      FIG. 24  is a side elevation view of the locking cam of  FIG. 22 ;  
         [0048]      FIG. 25  is a bottom elevation view of the locking cam of  FIG. 22 ;  
         [0049]      FIG. 26  is an engaging end axial view of the locking cam of  FIG. 22 ;  
         [0050]      FIG. 27  is a perspective view of a connector according to an alternative embodiment of the invention;  
         [0051]      FIG. 28  is a top plan view of the connector shown in  FIG. 27 ;  
         [0052]      FIG. 29  is a side elevation view of the connector shown in  FIG. 27 ;  
         [0053]      FIG. 30  is an end elevation view of the connector shown in  FIG. 27 ;  
         [0054]      FIG. 31  is a perspective view of an extending shaft according to an embodiment of the invention shown with a fixed jaw fitting;  
         [0055]      FIG. 32  is a side elevation view of the extending shaft of  FIG. 31 ;  
         [0056]      FIG. 33  is a top view of the extending shaft of  FIG. 31 ;  
         [0057]      FIG. 34  is a side elevation cutaway view of the extending shaft shown in  FIG. 32 ;  
         [0058]      FIG. 35  is an enlarged cutaway view of the radial opening and the axial opening of the body of a fixed jaw shown in  FIG. 34 ;  
         [0059]      FIG. 36  is a top view of the radial opening shown in  FIG. 35 ;  
         [0060]      FIG. 37  is a perspective view of an articulating jaw according to an embodiment of the invention;  
         [0061]      FIG. 38  is a side elevation view of the articulating jaw shown in  FIG. 37 ;  
         [0062]      FIG. 39  is a top view of the articulating jaw shown in  FIG. 37 ;  
         [0063]      FIG. 40  is a side elevation cutaway view of the articulating jaw shown in  FIG. 38 ;  
         [0064]      FIG. 41  is an enlarged cutaway view of the radial opening and the axial opening of the body of the articulating jaw shown in  FIG. 40 ;  
         [0065]      FIG. 42  is a top view of the radial opening shown in  FIG. 41 ;  
         [0066]      FIG. 43  is a perspective view of a retaining ring according to an embodiment of the invention;  
         [0067]      FIG. 44  is an end elevation view of the retaining ring shown in  FIG. 43 ;  
         [0068]      FIG. 45  is a perspective view of a connector according to an alternative embodiment wherein the housing and the extending shaft are bent;  
         [0069]      FIG. 46  is a front elevation view of the connector shown in  FIG. 45 ;  
         [0070]      FIG. 47  is a perspective view of a connector according to an alternative embodiment wherein the connector incorporates two articulating jaws;  
         [0071]      FIG. 48  is a front elevation view of the connector shown in  FIG. 47 ;  
         [0072]      FIG. 49  is a top view of the connector shown in  FIG. 47 ;  
         [0073]      FIG. 50  is a partial perspective view of an alternative embodiment of the invention wherein the extending shaft has circumferential grooves, shown in an unlocked position;  
         [0074]      FIG. 51  is a side elevation view of the connector shown in  FIG. 50 ;  
         [0075]      FIG. 52  is a partial perspective view of the connector shown in  FIG. 50 , shown in a locked position;  
         [0076]      FIG. 53  is a side elevation view of the connector shown in  FIG. 52 ;  
         [0077]      FIG. 54  is a partial perspective view of an alternative embodiment of the invention wherein the extending shaft has circumferential grooves but the shaft directly interfaces the locking collar, shown in an unlocked position;  
         [0078]      FIG. 55  is a side elevation view of the connector shown in  FIG. 54 ;  
         [0079]      FIG. 56  is a perspective view of the connector shown in  FIG. 54 , shown in a locked position;  
         [0080]      FIG. 57  is a side elevation view of the connector shown in  FIG. 56 ;  
         [0081]      FIG. 58  is a perspective view of an alternative embodiment of the invention utilizing a portion of the housing to articulate;  
         [0082]      FIG. 59  is a side elevation view of the connector shown in  FIG. 58 ;  
         [0083]      FIG. 60  is a top view of the connector shown in  FIG. 58 ;  
         [0084]      FIG. 61  is a perspective view of an alternative embodiment of the invention having two fixed jaws;  
         [0085]      FIG. 62  is a side elevation view of the connector shown in  FIG. 61 ;  
         [0086]      FIG. 63  is a top view of the connector shown in  FIG. 61 ;  
         [0087]      FIG. 64  is a partial perspective view of an alternative embodiment of the invention utilizing a helical ratcheting extending shaft, shown in an unlocked position;  
         [0088]      FIG. 65  is a side elevation view of the connector shown in  FIG. 64 ;  
         [0089]      FIG. 66  is a partial perspective view of the connector shown in  FIG. 64 , but shown in a locked position;  
         [0090]      FIG. 67  is a side elevation view of the connector shown in  FIG. 66 ;  
         [0091]      FIG. 68  is a partial perspective view of an alternative embodiment of the invention utilizing a taper lock;  
         [0092]      FIG. 69  is a side elevation view of the connector shown in  FIG. 68 ;  
         [0093]      FIG. 70  is a perspective view of an alternative embodiment of the invention employing a housing bent in multiple planes;  
         [0094]      FIG. 71  is a side elevation view of the connector shown in  FIG. 70 ; and  
         [0095]      FIG. 72  is a top view of the connector shown in  FIG. 70 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0096]     While the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which particular embodiments and methods are shown, it is to be understood from the outset that persons of ordinary skill in the art may modify the invention herein described while achieving the functions and results of this invention. Accordingly, the description that follows is to be understood as illustrative and exemplary of specific embodiments within the broad scope of the present invention and not as limiting the scope of the invention. In the following descriptions, like numbers refer to similar features or like elements throughout. As stated before, the invention is usable in a variety of medical applications and indeed is not limited to spinal applications. The invention will be denoted as connector  10 , it being understood that a variety of implant locations are possible. For ease of understanding, however, since spinal applications currently see great benefit from the invention, the following description is made with reference to spinal applications.  
         [0097]      FIGS. 1, 2 , and  19  show connectors  10  according to an embodiment of the invention in use as connectors to secure and connect two spinal rods  12 . The connectors  10  can have fixed jaws  100 , articulating jaws  200 , or a combination of fixed and articulating jaws. The connectors  10  can thus accommodate rods  12  in any orientation and spatial arrangement.  
         [0098]      FIGS. 3-6  show additional views of a connector  10  according to an embodiment of the invention. The connector  10  generally comprises a two-piece body having an extending shaft  20  and a housing  40 ; a rotor  60 ; and a locking collar  70 . Each end of the connector  10  has a fitting  80  for engaging a structure (e.g., a rod  12 , a vertebral body, and the like). In embodiments wherein the connector  10  is used to connect rods  12 , the preferable fittings  80  comprise jaws  90  for engaging the rod  12 . The jaws  90  can be in the form of a fixed jaw  100  or an articulating jaw  200 , depending on the needs of the surgeon. Each fitting  80  includes a proximal end  81  and a distal end  82 . The proximal end  81  preferably engages the connector  10  while the distal end  82  preferably engages other structures (for example, rods  12  in some embodiments or vertebral bodies in other embodiments, to name just a couple).  
         [0099]      FIGS. 7-10  show a housing  40  of an adjustable embodiment for use with an articulating jaw  200 . The housing  40  has a first portion  41  and a second portion  42  and preferably comprises two parts: a body  43  and a rotor  60 . The first portion  41  preferably is attachable to an articulating jaw  200  (described below). The second portion  42  receives the extending shaft  20  (described below). The housing  40  is generally cylindrical with a first axial opening  44  therein for receiving the articulating jaw  200  and a second axial opening  45  therein for receiving the extending shaft  20 . The rotor  60  is located in the second axial opening  45 . The rotor  60  is generally cylindrical having an outer surface  61  and an inner surface  62 . The inner surface  62  preferably contains one or more helical grooves  63  thereon so as to mate with corresponding helical grooves of the extending shaft  20 . The outer surface  61  preferably contains circumferential grooves  64 .  
         [0100]     The second portion  42  preferably has a generally stepped cylindrical shape with a proximal end  46  having a first outer surface  48  and a distal end  47  having a second outer surface  49 , wherein the second outer surface  49  has a diameter greater than that of the first outer surface  48 . One or more slots  50  are formed in the first and second outer surfaces  48 ,  49 . A ramping surface  51  provides a transition between the first outer surface  48  and the second outer surface  49 . A lip  52  preferably is provided at the distal end of the ramping surface  51 .  
         [0101]     Referring to  FIGS. 31-36 , a typical extending shaft  20  is depicted. These figures show a fixed jaw  100  attached as the fitting  80 , but recall that many types of fittings  80  are possible, including articulating jaws  200  (when used to connect rods  12 ) or other forms of endplates and so forth (when used as a corpectomy device). The extending shaft  20  has a first end  21  and a second end  22  wherein the first end  21  is insertable into the second axial opening  45  of the second portion  42  and wherein the second end  22  is typically fitted with fitting  80 . The extending shaft  20  has one or more helical grooves  23  disposed about its outer surface  24 . A groove  25  is preferably located near the first end  21 . This groove  25  will receive a retaining ring  26  (see  FIGS. 43-44 ) which has a leading surface  27  and a trailing surface  28  and an inner diameter  29  and an outer diameter  30 . As with many retaining rings, retaining ring  26  is resiliently expandable (such that inner diameter  29  and outer diameter  30  increase) so as to be fitted over the extending shaft  20  and moved to its residence in the groove  25 , whereupon it contracts to its equilibrium dimensions. Similarly, the retaining ring  26  is resiliently contractible (such that inner diameter  29  and outer diameter  30  decrease) so as to be forcibly inserted into the second axial opening  45  past a structure that has an opening smaller than the outer diameter  30  (which could be a structure within the second portion  42  or which could be the inner surface  72  of the locking collar  70  (described below), as but two examples).  
         [0102]     Referring to  FIGS. 16-18 , surrounding the body  43  is preferably a locking collar  70 . The locking collar  70  is generally cylindrical in shape and comprises an outer surface  71  and an inner surface  72  and a proximal end  74  and a distal end  75 . One or more protrusions  73  extend inwardly from the inner surface  72 . The protrusions  73  are preferably stepped such that they have a first height  76  at the proximal end  74  and a second height  77  at the distal end  75 , wherein the second height  77  is greater than the first height  76 . The protrusions  73  reside in the slots  50 , thus locating the locking collar  70  on the second portion  42  of the body  43 . The locking collar  70  is slideable between a first unlocked position and a second locked position. In the first unlocked position, the locking collar  70  is located toward the proximal end  46  on the first outer surface  48  and the protrusions  73  do not engage the circumferential grooves  64  of the rotor  60 . As the locking collar  70  is slid toward the distal end  47 , the inner surface  72  of the locking collar  70  begins contacting the ramping surface  51 . In the lock position the locking collar  70  passes over lip  52  and the inner surface  72  contacts the second outer surface  49 . In this position, the second height  77  of the protrusions  73  engages one or more circumferential grooves  64  on the outer surface  61  of the rotor  60 . In this position, the protrusions  73  prevent the rotor  60  from rotating about its axis.  
         [0103]     With continuing reference to  FIGS. 31-36 , the fitting  80  is shown in this embodiment as a fixed jaw  100 . The fixed jaw  100  shown here comprises a body  101  having a proximal end  102  and a distal end  103 ; an upper surface  104  and a lower surface  105 ; and a first side surface  106  and a second side surface  107 . In the embodiment shown for connecting rods  12 , a rod opening  108  extends through the first and second side surfaces  106 ,  107  and is preferably open at the lower surface  105 . The rod opening  108  forms an inner surface  109  that forms a partial cylindrical shape. The inner surface  109  has an axial opening  110  near the proximal end  102  for communication with a locking cam  90  (described below). The locking cam  90  is insertable in a radial opening  111  preferably located in the upper surface  104 . The locking cam  90  is preferably retained in the radial opening  111  by a retaining ring  112  with structure and function similar to that of retaining ring  26 .  
         [0104]     Referring now to  FIGS. 7-10  and  15 , the first portion  41  is shown as attachable to a fitting  80  that takes the form of an articulating jaw  200 . The first portion  41  preferably has a generally stepped open cylindrical shape with a proximal end  53  having a first outer surface  55  and a distal end  54  having a second outer surface  56 , wherein the second outer surface  56  has a diameter greater than that of the first outer surface  55 . Grooves  57  are formed in the distal end  54  at the first axial opening  44  so as to create resilient fingers  58 . The resilient fingers  58  have an entrance diameter  58 A and an internal opening  58 B having a diameter  58 C located a distance within the first portion  41 , wherein the diameter  58 C is greater than the entrance diameter  58 A. A ramping surface  59  provides a transition between the first outer surface  55  and the second outer surface  56 . A collar  199  having a generally open cylindrical shape has an outer surface  198  and an inner surface  197  and is assembled first to reside about the first outer surface  55  in an unlocked position. The collar  199  is slideable distally from the unlocked position to a locked position wherein the inner surface  197  surrounds the second outer surface  56 . In this position, since the second outer surface  56  has a diameter greater than the first outer surface  55 , the inner surface  197  of the locking collar  199 , as it moves along ramping surface  59  and into the locking position, forces resilient fingers  58  to deflect inwardly. When a ball  213  (described below) is present within the internal opening  58 B, this deflection locks the fingers  58  onto the outer surface of the ball  213 , thus maintaining the articulating jaw  200  in a desired orientation.  
         [0105]     Referring to  FIGS. 37-42 , a particular articulating jaw  200  is shown. The articulating jaw  200  has many of the same structures as that of the fixed jaw  100 , and so the similar features will not be further described. These similar features include a body  201  having a proximal end  202  and a distal end  203 ; an upper surface  204  and a lower surface  205 ; a first side surface  206  and a second side surface  207 ; a rod opening  208 ; inner surface  209 ; axial opening  210 ; radial opening  211 ; and retaining ring  212 . Additionally, however, the articulating jaw  200  further comprises a ball  213  located at the proximal end  202 . The ball  213  can take several shapes, including spherical and ovoidal, but is preferably spherical. The ball  213  has a diameter  214  that is preferably larger than the entrance diameter  58 A and less than or equal to the diameter  58 C.  
         [0106]     Referring now to  FIGS. 3, 4 ,  6 , and  22 - 26 , each jaw  90 , whether fixed or articulating, preferably has a locking cam  91  for alternately engaging or disengaging a rod  12  therein. A particularly useful embodiment of a locking cam  91  is shown in  FIGS. 22-26 , though many other types of connectors or cams can be used. The locking cam  91  generally comprises an engaging end  92  and a driving end  93 , wherein the engaging end  92  is fitted with a complex curvate surface  94  having at least a first curvate surface  95  and a second curvate surface  96  such that in an unlocked position, the rod  12  can slide freely within the jaw  90 , and in a locked position, the rod  12  is securely locked to the jaw  90  of the connector  10 . The locking cam  91  can have a retaining mechanism  97  to keep the locking cam  91  in the jaw  90 , such as a retaining ring that snaps into an undercut  98  in the jaw  90 . Many embodiments of the engaging end of the locking cam  91  are possible to accomplish this. The embodiment shown in  FIG. 15  utilizes a complex curvature such that in section view—in an unlocked position (see the left jaw  90 )—the first curvate surface  95  is located adjacent the rod  12 , and the second curvate surface  96  is located away from the rod  12 . The first curvate surface  95  may have a radius of curvature that is greater than that of the second curvate surface  96 . Alternatively, the first curvate surface  95  may have the same radius of curvature as that of the second curvate surface  96  but may offset the origin of the curvature farther away from the centerline of the locking cam  91 . Upon rotation of the locking cam  91  from the unlocked to the locked position (see the right jaw  91  shown in  FIG. 15 ), gradually the second curvate surface  96  is brought into contact with the rod  12 , which wedges the rod  12  against the inner surface  109  within the jaw  90 , thereby locking the rod  12  in position. This ability to draw the rod  12  up to the jaw  90  compensates for any misalignment between the opposing rods  12 .  
         [0107]      FIGS. 20-26  and  37 - 42  show one example of the visual and tactile feedback provided by the locking cams  91  of the invention on use with an articulating jaw  200 . As stated above, the locking cam  91  generally comprises an engaging end  92  and a driving end  93 . The driving end  93  is preferably circular in cross section and has a cavity  93 A to receive a driving instrument (not shown) and an appurtenant stop  93 B disposed at a location along its perimeter. The locking cam  91  is inserted into the radial opening  211  and is secured therein by a retaining mechanism  97 . The radial opening  211  preferably comprises a substantially circular opening having a discontinuity  211 A disposed out of phase with the appurtenant stop  93 B when in the unlocked position. A driving instrument turns the locking cam  91  the desired amount (preferably approximately 180 degrees). This turning rotates the engaging end  92  about the locking cam&#39;s  91  axis of rotation, which brings the second curvate surface  96  into contact with the rod  12 , which wedges the rod  12  against the inner surface  209 . When fully turned, the appurtenant stop  93 B engages the discontinuity  211 A, which visually and tactily informs the surgeon that the cam is locked.  
         [0108]      FIGS. 27-30  show an alternative embodiment of a connector  10  of fixed length. Various sizes of such connectors  10  can be manufactured according to common lengths needed for patients of varying sizes and varying portions of the spine. In this embodiment, although no length adjusting mechanism as described above is present, the novel locking cam  91  structure to secure the rods  12  is present.  
         [0109]      FIGS. 45 and 46  show an alternative embodiment of a connector  10  wherein the extending shaft  20  and the housing  40  are pre-bent to account for spinal curvature. Such embodiment can better reduce or eliminate interference of the connector  10  with vertebrae or other structures.  
         [0110]      FIGS. 47-49  show an alternative embodiment of a connector  10  wherein the connector  10  contains two articulating jaws  200 . Such embodiment is useful where the rods  12  are highly divergent. Without multiple articulating jaws  200 , bending may be required for some connectors  10 . This embodiment employs an articulating jaw  200  on both ends of the connector  10  to eliminate the need for any bending. It also enables better placement of the connector in vivo to avoid any interference from surrounding structures. The articulating jaw in the extending shaft  20  is similar in structure and function to that of the already described articulating jaw  200 , providing means for rotating the jaw; locking it to the extending shaft  20 ; and telescoping the extending shaft  20  out of the housing  40 .  
         [0111]     FIGS  50 - 53  show an alternative embodiment of a connector  10  wherein the extending shaft  20  comprises circumferential grooves  23 A along the length thereof. The housing  40  has a corresponding ring  45 A with grooves, for example within second axial opening  45 , that will mate with the grooves  23 A on the extending shaft  20 . The extending shaft  20  moves relative to the housing  40 , thus varying the overall length of the connector  20 . The ring  45 A is deflectable such that once the extending shaft  20  is in the proper place the housing  40  can be locked down onto the extending shaft  20  via a locking collar  70 . The locking collar  70  is located preferably around the end of the housing  40  and locks the housing  40  on the extending shaft  20  by means of a cam feature or similar devices.  
         [0112]      FIGS. 54-57  show an alternative embodiment to the circumferential groove device. In this embodiment, the locking collar  70  directly interfaces the extending shaft  20 . The locking collar  70  has circumferential grooves  23 A on its inner diameter or portions thereof The locking collar  70  has an internal diameter that provides clearance to enable the extending shaft  20  to move axially relative to the housing  40 . Conversely the extending shaft  20  has a portion thereof devoid of grooves to allow it to move freely relative to the locking collar  70 . The locking collar  70  will be secured in place axially relative to the housing  40 , but will be free to rotate a certain degree in order to interface with the extending shaft  20 . When the desired length is reached the locking collar  70  can be turned a predetermined angle to engage the extending shaft  20 . Other means of preventing the extending shaft  20  from rotating within the housing  40  are possible, including, but not limited to keys, pins, noncircular shaped second axial opening  45 , and the like.  
         [0113]      FIGS. 58-60  show an alternative embodiment of a connector  10  wherein instead of providing an articulating jaw  200 , an articulating housing  40  is provided. Basically instead of employing the first axial opening  44  to receive the ball  213  of the articulating jaw  200 , the first portion  41  of the housing  40  receives a ball. A locking mechanism can be incorporated into the connector  10  to permit the housing  40  to be fixed at a desired angle. The housing  40  preferably can pivot in all planes. Articulating jaws  200  as described above can be incorporated into this embodiment to allow for even more capability to interface with diverging rods.  
         [0114]      FIGS. 61-63  show another alternative embodiment of a connector  10  wherein two fixed jaws  100  are in use. Any adjustments made to the connector to account for diverging rods  12  would have to be made by bending the connector  10  either at the extending shaft  20  or on the housing  40  itself. Bending could be made in any direction and would only be limited by the physical properties of the material.  
         [0115]      FIGS. 64-67  show an alternative embodiment of a connector  10  having a ratcheting telescoping shaft  20 . The shaft  20  contains helical grooves  23  similar to that previously described. The shaft  20  interfaces a rotor  60  that similarly has internal helical grooves  63  matching the external profile of the shaft  20 . The rotor  60  likewise comprises circumferential grooves  64  or other indentations or extrusions on its external surface, again like that described above. A split ring  70 A is provided that engages the circumferential grooves  64 . The split ring  70 A has engaging features on its internal surface which spring open when the circumferential grooves  64  rotate past them. This provides a ratcheting feel to the telescoping of the shaft  20 . The advantage is that a shaft  20  can be placed at a predetermined length before implantation and then small adjustments and locking could be made in vivo. Locking is be accomplished by placing a ring, collar, or similar device onto the split ring  70 A to prevent it from springing open. This in turn would prevent the rotor  60  from turning and the shaft  20  from translating.  
         [0116]      FIGS. 68-69  show an alternative embodiment of a connector  10  utilizing a different means to lock the rotor  60 . In this embodiment, a taper lock is used in place of the engaging features described above. The rotor  60  is cylindrical in shape but has a taper on the outer surface  61  in the direction of the rotational axis. A locking collar  70  has an inner surface  72  having a taper complementing that of the outer surface  61  of the rotor  60 . The locking collar  70  resists rotation relative to the housing  40  thereby. Locking is accomplished by moving the locking collar  70  to interface the rotor  60  via the taper lock, thus preventing the rotor  60  from turning.  
         [0117]      FIGS. 70-72  show an alternative embodiment of a connector l that is pre-bent in multiple planes. Any combination of bends in planes parallel to the rods  12 , perpendicular to the rods  12 , or in planes between the two are possible. This would account for any misalignment and divergence of the rods  12 . The connector  10  is intended to accommodate rods  12  that are divergent and at different heights. This embodiment is a variation of the embodiment shown in  FIGS. 45 and 46 .  
         [0118]     While there has been described and illustrated particular embodiments of a novel adjustable implant device, it will be apparent to those skilled in the art that variations and modifications may be possible without deviating from the broad spirit and principle of the present invention, which shall be limited solely by the scope of the claims appended hereto.