Abstract:
A position-adjustment device having particular applicability for surgical instrumentation. The system comprises a body connected to an elongate member in such an arrangement as to have interchangeable locked and unlocked states. In the unlocked state, the body is free to move along the elongate member, and in the locked state the body is prevented from moving along the elongate member.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a continuation application of U.S. Ser. No. 10/054,840, filed Jan. 23, 2002, which claims priority of French Application No. 0100873 filed on Jan. 23, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention relates to a position adjustment device having particular applicability to surgical instrumentation.  
           [0003]    In the event of traumas, simple or multiple fractures of one or more vertebrae in the spine can give rise to various configurations that require corrective movements to be applied in order to return the spine to its original shape, in particular concerning the curvature involved in lordosis and kyphosis. Special instruments are used for this purpose that make such restoration possible in cooperation with osteosynthesis systems that are known from elsewhere. Document DE G-91-12 466.2 describes such instrumentation including an adjustment system which comprises a threaded rod having two oppositely-handed threads situated on either side of drive means. Each of the threads engages in a tapped bore of a body connected to an element of the instrumentation. Operating such a system is lengthy because of the pitch of the threads and also because of the fact that during handling, surgical gloves come into contact with the threads which have sharp edges that are liable to catch and tear the gloves, thus requiring additional precautions to be taken. This lengthens the time required to perform an operation which increases the likelihood of harm to the patient.  
         SUMMARY OF THE INVENTION  
         [0004]    An object of the invention is to provide an adjustment device for instrumentation for surgery of the spine, which can be put into place precisely and quickly.  
           [0005]    To do this, according to the invention, there is provided a position-adjustment device, with particular applicability for surgical instrumentation, in particular for surgery of the spine. The device is used with an elongate member, which, as known to those of ordinary skill in the art of surgical instrumentation, is suitable for being connected to a first element of a surgical instrument. The device further comprises a body suitable for being fastened to the elongate member and for being connected to a second element of the surgical instrument, as well as a connection for connecting the elongate member to the body. The device is arranged to have an unlocked state in which the connection allows the elongate member to slide relative to the body and a locked state in which the connection prevents the elongate member from sliding relative to the body.  
           [0006]    Thus, the unlocked state enables adjustment of position to be performed simply, precisely, and quickly, while the locked state enables the selected position to be locked quickly. As a result, such a device can be operated simply, precisely, and quickly.  
           [0007]    Advantageously, the connection is arranged to prevent the elongate member from sliding relative to the body by a wedging effect.  
           [0008]    Advantageously, the connection comprises at least one elastically deformable element.  
           [0009]    Advantageously, the deformable element is suitable for implementing a wedging effect.  
           [0010]    Advantageously, the device is arranged in such a manner that in the locked state, sliding is locked in a single direction.  
           [0011]    Advantageously, the deformable element presents a bearing surface, and the elongate member presents a contact face suitable for coming into contact with the bearing surface in the locked state.  
           [0012]    Thus, the longitudinal member entrains the deformable element towards the locked position because of the contact between the contact face and the bearing surface and without any intervention by the operator on the deformable element. The operator does not act on the deformable element, so the operator&#39;s hands do not come into contact with sharp edges. As a result there is no risk of damaging or tearing gloves during the operation.  
           [0013]    Advantageously, the contact face is smooth, locking being obtained by friction.  
           [0014]    Advantageously, the contact face is knurled.  
           [0015]    Advantageously, the bearing surface includes knurling.  
           [0016]    Advantageously, the contact face presents recesses, in particular grooves.  
           [0017]    Advantageously, the bearing surface has a projection suitable for being received in the recesses.  
           [0018]    Advantageously, the deformable element is split over all or part of its length.  
           [0019]    Advantageously, the deformable element has deformable tongues at one end.  
           [0020]    Advantageously, the deformable element has an end for implementing unlocking.  
           [0021]    Advantageously, the deformable element is conical in shape.  
           [0022]    Advantageously, the end for implementing unlocking includes a bearing rim.  
           [0023]    Advantageously, the connection includes a second elastically deformable element.  
           [0024]    Advantageously, the second deformable element is suitable for preventing sliding in the other direction of displacement.  
           [0025]    Advantageously, the second deformable element is a mirror image of the first deformable element.  
           [0026]    Advantageously, the body can be dismantled into at least two portions.  
           [0027]    Advantageously, the body includes a connection for interconnecting the two portions, in particular, a ring. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    Other characteristics and advantages of the present invention appear from the following description of an embodiment. In the accompanying drawings:  
         [0029]    [0029]FIG. 1 is a section view of an embodiment of the invention shown in full;  
         [0030]    [0030]FIG. 2 is an exploded perspective view of the FIG. 1 embodiment without the elongate member;  
         [0031]    [0031]FIG. 3 a  is a perspective view of the deformable element of the FIG. 1 embodiment of the invention;  
         [0032]    [0032]FIG. 3 b  is a section view along line  3   b  through the deformable element of FIG. 3 a;    
         [0033]    [0033]FIG. 4 a  is a perspective view of a fraction of the body of the FIG. 1 embodiment of the invention;  
         [0034]    [0034]FIG. 4 b  is a section view along line  4   b  of the FIG. 4 a  body portion;  
         [0035]    [0035]FIGS. 5 and 6 are section views through the FIG. 1 embodiment while it is in operation; and  
         [0036]    [0036]FIG. 7 is a diagrammatic view of the FIG. 1 embodiment in use in an operation. 
     
    
     DETAILED DESCRIPTION  
       [0037]    An embodiment of the invention is described with reference to the figures. In FIG. 1, the position-adjustment device  1  comprises a hollow body  3  suitable for slidably receiving an elongate member, or rod  2 , of circular section, together with a pair of elastically deformable elements  8  and  10  each having a circular plate  14  fixed to one end thereof.  
         [0038]    The hollow body  3  comprises two half-shells  4  and  6  interconnected by a ring  12 . The half-shell  6  is a mirror image of the half-shell  4  about a plane perpendicular to the axis of revolution A of the body  3 . Only one half-shell is therefore described in detail.  
         [0039]    With reference to FIGS. 2, 4 a , and  4   b , the half-shell  4  has a through orifice  18  extending along its axis of revolution A. The half-shell  4  has an outside surface  61  and two axial end surfaces  34  and  60 . The end surface  60  joins the outside surface  61  via a surface  26  of rounded shape. A portion of the outside surface  61  is replaced by a flat  48  parallel to the axis of revolution A. Perpendicular to this flat  48 , a radial through tapped orifice  50  opens out to the inside of the orifice  18 . The orifice  18  is made up of a plurality of portions: a cylindrical first portion of circular section defined by a surface  52  presents a first diameter; then a second cylindrical portion of circular section defined by a surface  54  presents a second diameter greater than the diameter of the first portion. The tapped orifice  50  opens out into this portion. A third portion is in the form of a frustoconical surface  56  which extends the orifice  18  causing it to expand from the diameter of the second portion to the diameter of a fourth portion, itself defined by a forth cylindrical portion having a cylindrical surface  58  of circular section. It is explained below that the surface  56  forms a bearing surface.  
         [0040]    The ring  12  for interconnecting the two symmetrical half-shells  4  and  6  has a cylindrical outside face  22  whose diameter is substantially equivalent to the diameter of the fourth portion of each of the half-shells. The ring  12  also presents a cylindrical inside surface  20 . The length of the ring  12  is equivalent to twice the width of the fourth portion of each of the half-shells  4  and  6 .  
         [0041]    The body  3  is formed as follows: the ring  12  is inserted in the fourth portion of the orifice  18  of the first half-shell. Because of its double width, once the ring  12  has been put into place in the first half-shell, it projects from the face  34  of the half-shell. Thereafter, the second half-shell is engaged on the ring  12  until its face  34  comes to bear against the face  34  of the first half-shell. The body  3  is thus completely formed. The outside diameter of the ring  12  and the inside diameter of the fourth portion in each of the half-shells are selected in such a manner that the ring is inserted as a force-fit so as to be capable of holding the body  3  together while it is in use during surgery, while nevertheless remaining separable by a theatre nurse to enable the device to be cleaned completely between two operations. In order to make assembly more secure, a link element (not shown) can optionally be used to join the two half-shells  4  and  6  together. The link element may be fixed to the half-shells by means of threaded members (not shown) suitable for engaging the tapping in the orifices  50  of each of the half-shells  4  and  6 , the link element being suitable for bearing against the flats  48 .  
         [0042]    With reference to FIGS. 2, 3 a , and  3   b , there follows a description of the deformable elements  8  and  10 . Element  10  is a mirror image of element  8  about a plane perpendicular to the axis of revolution A of the elements. Only one of the two elements is therefore described. Elastically deformable element  8  comprises two main portions  32  and  33 . The general shape of the deformable element  8  is that of a tube. The portion  32  presents a first cylindrical surface  42  with a first diameter and a second surface  44  with a second diameter slightly greater than the diameter of the surface  42 . The portion  32  is separated from the portion  33  of deformable element  8  by a concave groove  36  forming a complete circle around deformable element  8  and occupying a plane perpendicular to its axis. Portion  33  of deformable element  8  is made up of a plurality of tongues  30  that are uniformly distributed over the entire circumference of element  8 . In this case, there are eight tongues  30 . Each tongue  30  is separated from the next tongue by a slot  46  extending from the groove  36  to the free axial end of portion  33  of element  8 . In the groove  36 , each slot  46  becomes a circular through orifice  40 . At the free end of portion  33  of deformable element  8 , each tongue  30  is terminated by a projection extending radially outwards relative to element  8 , and presenting a surface  28  that is conical in shape. Still at its free end, opposite surface  28 , each tongue has a convex projection that is preferably of circular section extending radially towards the inside of deformable element  8 . As explained below, portion  33  is the portion of element  8  which deforms in use. This deformation is due to each tongue being suitable for deforming essentially in the vicinity of the groove  36 .  
         [0043]    The diameter of surface  44  is substantially equivalent to the diameter of the first portion of orifice  18  defined by surface  52 . The diameter of surface  42  is substantially equivalent to the diameter of orifice  16  present in the plates  14  that are described briefly, below.  
         [0044]    The plates  14  constitute rings, each presenting a through orifice  16  and a rounded outer rim  24 . The plates  14  are suitable for being mounted on portion  32  of each of the deformable elements  8 ,  10 , so as to cover its surface  42 . With reference to FIG. 1, the elongate member  2 , suitable for being received inside body  3 , is a circular section rod on the axis of revolution A, and presents a plurality of circumferential grooves  62  that are uniformly distributed along its entire length. These grooves  62  are of circular section.  
         [0045]    The following is a description of how the position-adjustment device  1  is assembled. The first deformable element  8  is inserted in the half-shell  4 , for example, in such a manner that the surface  44  occupies the first portion of the orifice  18 , in contact with surface  52 . Thereafter, a first plate  14  is mounted as a force-fit on portion  32  of first deformable element  8  in such a manner that the orifice  16  of the plate  14  receives the surface  42  of the deformable element. Then the ring  12  is inserted as a force-fit into the fourth portion of the orifice  18  of the half-shell in such a manner that surface  22  is in contact with surface  58 . Thereafter, the second deformable element  10  is inserted in the second half-shell  6  in the same manner as deformable element  8  was inserted in the first half-shell  4 , and then still in the same manner, the second plate  14  is put into place on portion  32  of deformable element  10 . Finally, the second half-shell  6  is inserted on the ring  12  so as to close the body  3  as a whole. It should be observed that in each of the half-shells, each of the deformable elements is retained at one end by the presence of plate  14  on its portion  32  and at its other end by the presence of the projections having surfaces  28  at the ends of tongues  30  since each of the surfaces  28  is suitable for coming into contact with the surface  56  of the orifice  18 . Secondly, when plate  14  comes into contact with the rear face  60  of a half-shell, the surface  28  of each of the tongues  30  is spaced apart from the surface  56  of the half-shell. Conversely, when each of the surfaces  28  of each of the tongues  30  is in contact with the surface  56  of the half-shell, then the plate  14  is no longer in contact with the surface  60  of the half-shell. Finally, in use, the elongate member  2  is then inserted into the assembly.  
         [0046]    The operation of the position-adjustment device  1  is described below with reference to FIGS. 5, 6, and  7 . A spinal column has a vertebra V 3  which presents multiple fractures. This vertebra V 3  is associated with two healthy vertebrae V 1  and V 2  on either side via vertebral disks I 1  and I 2 . As it is known to those of ordinary skill in the art, it is assumed that the elongate member  2  is connected to an element E 1  of a surgical instrument that is engaged in the vertebra V 1 , while the body  3  is connected to a second element E 2  of the same surgical instrument that is engaged with the vertebra V 2 .  
         [0047]    The operation of moving the body  3  in the direction of arrow F is described with reference to FIG. 5. For this purpose, the operator applies a force F to plate  14  connected to deformable element  8 . This force F enables the deformable element  8  to be moved so as to bring the plate  14  into contact with the face  60  of the half-shell  4  of the body  3 , and separate the surfaces  28  of the blades  30  from contact with the surface  56  of the corresponding half-shell. As deformable element  8  moves in the direction of arrow F relative to body  3 , by virtue of its circular projections  38  engaging a groove  62  in the elongate member  2 , deformable element  8  entrains the elongate member  2  in the direction of arrow F. Thus elongate member  2  is also caused to move, relative to the body  3 , in the direction of arrow F. Since the other deformable element  10  has its projections  38  engaged in another groove  62  of the elongate member  2 , when the elongate member  2  is entrained in the direction of arrow F, this movement causes deformable element  10  to also move in the direction of arrow F until the surfaces  28  of each of the blades of the second deformable element  10  come into contact with the surface  56  of the half-shell  6 . As a result, the second plate  14  connected to the second deformable element  10  is moved away from the face  60  of the second half-shell  6 . FIG. 5 depicts this condition.  
         [0048]    At this point, while maintaining force F on the first plate  14 , the elongate member  2  may be moved in the direction of arrow F′, or as otherwise understood through relative movement, body  3  may be moved in the direction of arrow F relative to elongate member  2 . Because the projections  38  and the grooves  62  are circular in shape, and because of the new position of deformable element  8  where there is now clearance to allow for the outward radial movement of the various tongues  30  which deform essentially at the groove  36 , the projections  38  of the first deformable element  8  escape outwardly from the groove  62  of the elongate member  2  as the elongate member  2  moves in direction F′ relative to the body  3 , while force F is maintained on the first plate  14 .  
         [0049]    While moving in the direction of arrow F′ relative to body  3 , the elongate member  2  entrains the second deformable element  10  to move in direction D. This entrainment is similarly observed from the perspective of body  3  moving in the direction of arrow F relative to elongate member  2 . During this entrainment, the surfaces  28  of the second deformable element  10  move away from, and lose contact with, the surface  56  of the half-shell  6 , thus moving into a position having a clearance space that will allow for the tongues  30  of the second deformable element  10  to move radially outwardly when necessary. The entrainment of the second deformable element  10  ends when the second plate  14  makes contact with the face  60  of the half-shell  6 . At that point, with the continued application of force F on the first plate  14 , body  3  may continue to be moved in the direction of arrow F relative to the elongate member  2  over an arbitrary distance, while the projections  38  of the second deformable element  10  move radially out of and into passing grooves  62  of the elongate member  2  which is moving in the direction F′ relative to body  3 .  
         [0050]    Once the body  3  has reached the desired position, the operator ceases to apply the force F that was being exerted on the first plate  14 . Deformable element  8  therefore gets entrained by the elongate member  2  moving in direction F′ relative to the body  3 , and, itself, moves in direction F′ relative to body  3  until the faces  28  of each of the tongues  30  of deformable element  8  come into contact with surface  56  of half-shell  4 , thereby locking the device in position by holding the projections  38  in the groove  62  under a force D′ generated by contact between surface  56  and surfaces  28 . FIG. 6 depicts this condition.  
         [0051]    Symmetrically, by acting on the second plate  14  in a manner identical to that described above, the operator can move the body  3  in the direction opposite to arrow F.  
         [0052]    Similarly, by acting on both plates  14  simultaneously as described above, the operator can cause the body  3  to slide an arbitrary distance in either direction along the elongate member  2  so as to position the body  3  at any desired location.  
         [0053]    Naturally, numerous modifications can be made to the invention without thereby going beyond the ambit thereof.  
         [0054]    For example, the grooves  62  of the elongate member  2  could be replaced by a knurled surface or by a smooth surface. Under such circumstances, the deformable elements could have a knurled surface instead of projections  38 . Locking in a position would then be obtained by means of friction.