Abstract:
An adjustable drill depth guide includes a first sleeve, a second sleeve and a stop member. The first sleeve includes a longitudinal axis and defines a helical slot disposed about the longitudinal axis. The second sleeve is concentrically arranged relative to the first sleeve and is axially adjustable relative to the first sleeve for adjusting a length of the adjustable drill depth guide. The stop member extends radially from the second sleeve and is disposed in the helical slot. The stop member is selectively received at various positions along the helical slot to positively locate the second sleeve relative to the first sleeve in the axial direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/731,663, filed on Nov. 30, 2012. The entire disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to an adjustable drill depth guide, and more particularly to a device and method for adjusting the depth of a drill bit into a bone. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     In general, the human musculoskeletal system is composed of a variety of tissues including bone, ligaments, cartilage, muscle, and tendons. Tissue damage or deformity stemming from trauma, pathological degeneration, or congenital conditions often necessitates surgical intervention to restore function. Surgical intervention can include any surgical procedure that can restore function to the damaged tissue or correct the deformity, which can require the use of one or more orthopedic prosthesis, such as orthopedic nails, screws, implants, etc. For example, in order to restore function to or correct a deformity of the spinal column, one or more implants can be coupled to each vertebral body and interconnected via a suitable device. Implants or anchors can be coupled to each vertebral body, and a connecting device, such as a rod, can be coupled to each of the anchors to stabilize or fix the vertebral bodies relative to each other. Generally, multiple anchors or bone screws can be attached to each vertebral body so that multiple rods can be used to stabilize the spinal column. Holes of various depths may be drilled in the vertebral bodies to prepare the bone to receive the bone screws. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     The present teachings relate to an instrument for use in preparing a bone to receive a bone screw. More specifically, the present teachings relate to a drill depth guide that can be quickly and easily adjusted to achieve a desired drill depth. 
     According to one particular aspect, the present disclosure provides an adjustable drill depth guide. The adjustable drill depth guide includes a first sleeve, a second sleeve, a third sleeve, and a biasing member. The first sleeve includes a longitudinal axis, a first proximal end, a first distal end, a first longitudinal bore extending from the first proximal end to the first distal end, a helical slot disposed about the longitudinal axis, and a plurality of notches extending axially from the helical slot. The second sleeve is at least partially disposed within the first longitudinal bore, and extends along the longitudinal axis from a second proximal end to a second distal end. The second sleeve includes a second longitudinal bore and a radially extending stop member. The radially extending stop member is selectively engageable with at least one notch of the plurality of notches. The third sleeve includes a third proximal end, a third distal end, and a third longitudinal bore extending from the third proximal end to the third distal end. The third sleeve is concentrically disposed relative to the first sleeve. The biasing member is disposed substantially adjacent to an outer wall of the third sleeve and biases the second proximal end in the direction of the third distal end. 
     According to another particular aspect, the present disclosure provides an adjustable drill depth guide. The adjustable drill depth guide includes a first sleeve, a second sleeve, and stop member. The first sleeve includes a longitudinal axis and defines a helical slot disposed about the longitudinal axis. The second sleeve is concentrically arranged relative to the first sleeve and is axially adjustable relative to the first sleeve for adjusting a length of the adjustable drill depth guide. The stop member extends radially from the second sleeve and is disposed in the helical slot. The stop member is selectively received at various positions along the helical slot to positively locate the second sleeve relative to the first sleeve in the axial direction. 
     According to yet another particular aspect, the present disclosure provides a method of adjusting the length of a drill depth guide. The method includes providing an adjustable drill depth guide that includes a first sleeve having a helical slot, a second sleeve at least partially disposed within the first sleeve, a radially extending stop member coupled to the third sleeve and operably disposed within the helical slot, and a biasing member biasing a distal end of the second sleeve in a first axial direction. The method also includes moving the radially extending stop member in a second axial direction opposite the first axial direction. The method further includes rotating the second sleeve relative to the first sleeve to move the radially extending stop member in at least one of the first axial direction and the second axial direction. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a perspective view of an adjustable drill depth guide constructed in accordance with the teachings of the present disclosure. 
         FIG. 2  is a front view of the adjustable drill depth guide of  FIG. 1 . 
         FIG. 3  is a rear view of the adjustable drill depth guide of  FIG. 1 . 
         FIG. 4  is a bottom view of the adjustable drill depth guide of  FIG. 1 . 
         FIG. 5  is a front view of the adjustable drill depth guide of  FIG. 1 . 
         FIG. 6  is a side view of the adjustable drill depth guide of  FIG. 1 . 
         FIG. 7  is another side view of the adjustable drill depth guide of  FIG. 1 . 
         FIG. 8  is a cross sectional view of the of the adjustable drill depth guide of  FIG. 1  taken along line  8 - 8  of  FIG. 2 . 
         FIG. 8A  is a close-up view of area  8 A of  FIG. 8 . 
         FIG. 9  is an exploded view of the adjustable drill depth guide of  FIG. 1 . 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     With reference to  FIGS. 1-9 , an adjustable drill depth guide assembly constructed in accordance with the present teachings is illustrated and identified at reference character  10 . The adjustable drill depth guide assembly  10  may be used to control the depth by which a tap or drill bit  12  penetrates a bone  14 . According to one exemplary use, the adjustable drill depth guide assembly  10  may be particularly adapted for use in spinal fixation procedures. It will also be appreciated, however, that the present teachings may be adapted to control the penetration depth of a drill bit into any type of material or component. 
     The adjustable drill depth guide assembly  10  may generally include a tip or end sleeve  16 , a control sleeve  18 , an adjustment sleeve  20 , a collar  22 , an inner sleeve  24 , a biasing member  26 , and a handle assembly  28 . As illustrated, the end sleeve  16 , the control sleeve  18 , the adjustment sleeve  20 , the collar  22 , and the inner sleeve  24  may together define a guide barrel  25  having a longitudinal axis  30  that accepts the drill bit  12 . 
     As illustrated in  FIGS. 8 and 8A , the end sleeve  16  may extend between a proximal end  32  and a distal end  34  along the longitudinal axis  30 , and may include a bore  36 , and a counterbore  38 . The bore  36  may extend between the proximal end  32  and the distal end  34  of the end sleeve  16 . The counterbore  38  may extend longitudinally from the proximal end  32 . As illustrated, an annular surface  42  extending between and connecting the bore  36  and the counterbore  38  may be tapered or chamfered to generally guide the drill bit  12  along the longitudinal axis  30  and in the direction of the bone  14 . 
     The proximal end  32  of the end sleeve  16  may include an externally threaded portion  44 . The distal end  34  of the end sleeve  34  may include a toothed portion  46  having a plurality of axially extending teeth. The toothed portion  46  may help to secure the placement of the adjustable drill depth guide assembly  10  relative to the bone  14  or other working surface. An outer surface  47  of the end sleeve  16  may include a knurled portion  48  to allow a user to better grip and maneuver the adjustable drill depth guide assembly  10 . 
     The control sleeve  18  may extend between a proximal end  50  and a distal end  52  along the longitudinal axis  30 . The control sleeve  18  may include a generally cylindrical neck portion  54  and a generally cylindrical body portion  56 . The body portion  56  may extend longitudinally from the proximal end  50  of the control sleeve  18  to a distal end  55  of the body portion  56 . The neck portion  54  may be integrally and concentrically formed with the body portion  56  and may extend longitudinally from the distal end  55  of the body portion  56  to the distal end  52  of the control sleeve  18 . The neck portion  54  may have a smaller diameter than the body portion  56  and may include an annular groove  57 . The annular groove  57  may support a retaining ring  59 . In an assembled configuration, the neck portion  54  may be concentrically and rotatably disposed within the counterbore  38  of the end sleeve  16 . 
     A bore  58  may extend longitudinally from the proximal end  50  to the distal end  52  of the control sleeve  18 . A counterbore  60  may extend longitudinally from the proximal end  50  to a location between the proximal end  50  and the distal end  52  of the control sleeve  18 . An annular surface  62  may extend between and connect the bore  58  and the counterbore  60 . As will be explained in more detail below, the annular surface  62  may be tapered or chamfered and may prevent axial displacement of the adjustment sleeve  20  relative to the control sleeve  18  in an assembled configuration. 
     The body portion  56  of the control sleeve  18  may include an aperture  64  and a helical slot  66 . The aperture  64  may extend laterally through the sidewall of the control sleeve  18  to allow a user to view the inner sleeve  24  within the bore  58 . It will be appreciated that the helical slot  66  may extend around the periphery of the control sleeve  18  any number of revolutions, or fractions thereof, within the scope of the present teachings. In one configuration, the helical slot  66  extends approximately seven hundred twenty degrees around the control sleeve  18 . The helical slot  66  may include a plurality of axially extending notches  70 . The notches  70  may extend axially in the direction of the distal end  52  of the control sleeve  18 , such that the lower edge (relative to the view in  FIG. 1 , for example) of the helical slot  66  has a generally scalloped or waved configuration. In one configuration, the axial distance between adjacent notches  70  may be approximately 2 millimeters. 
     The adjustment sleeve  20  may extend between a proximal end  72  and a distal end  74  along the longitudinal axis  30 . The proximal end  72  of the adjustment sleeve  20  and the distal end  34  of the end sleeve  16  may generally define a length of the drill depth guide  10  along the longitudinal axis  30 , and thus the distance by which the drill bit  12  extends beyond the distal end  34  of the end sleeve  16 . The adjustment sleeve  20  may include a generally cylindrical head portion  76  and a generally cylindrical stem portion  78 . The head portion  76  may have a larger diameter than the stem portion  78 . A generally frustoconical intermediate portion  80  may extend between and connect the head portion  76  and the stem portion  78 . While the adjustment sleeve  20  is described herein as including a generally cylindrical head portion  76 , a generally cylindrical stem portion  78 , and generally frustoconical intermediate portion  80  therebetween, it will be appreciated that the head portion  76 , the stem portion  78  and the intermediate portion may have other geometries within the scope of the present teachings. The head portion  76  may be integrally formed with the stem portion  78  and the intermediate portion  80  as a monolithic construct. 
     The adjustment sleeve  20  may further include a bore  84  and a aperture  88 . The bore  84  may extend longitudinally from the proximal end  72  to the distal end  74  of the adjustment sleeve  20 . The aperture  88  may extend laterally through the sidewall of the stem portion  78  of the adjustment sleeve  20 . 
     In an assembled configuration, the stem portion  78  of the adjustment sleeve  20  may be concentrically and rotatably disposed with the bore  58  of the control sleeve  18 . A radially extending stop member, such as a pin  90 , may extend through the helical slot  66  and into engagement with the aperture  88 . In one configuration, the aperture  88  may be internally threaded and the pin  90  may include an externally threaded portion  91 , such that rotating the pin  90  with a screwdriver (not shown) or other suitable tool will threadably engage the pin  90  with the aperture  88 . In other configurations, the pin  90  may be secured within the aperture  88  by utilizing a press-fit engagement, an adhesive, or other suitable technique. In one configuration, the pin  90  is permanently coupled within the aperture  88  using a press-fit engagement. 
     The collar  22  may extend between a proximal end  92  and a distal end  94  along the longitudinal axis  30 . While the collar  22  is generally illustrated as a cylindrical member, it will be appreciated that the collar  22  may have other geometries within the scope of the present teachings. The collar  22  may include a bore  96  and a counterbore  98 . The bore  96  may extend longitudinally through the collar  22  from the proximal end  92  to the distal end  94 . The counterbore  98  may extend longitudinally from the distal end  94  to a location between the proximal end  92  and the distal end  94  of the control sleeve  18 , and may include an internally threaded portion  100 . 
     In the assembled configuration, the collar  22  may be concentrically disposed around the end sleeve  16  and the control sleeve  18 . As illustrated, the threaded portion  100  of the collar  22  may engage the threaded portion  44  of the end sleeve  16 , so that the end sleeve  16  can be removed from the collar  22  for cleaning or otherwise servicing the assembly  10 . The neck portion  54  of the control sleeve  18  may be concentrically disposed within the collar  22  such that the bore  96  abuts the neck portion  54  of the control sleeve  18 , and the proximal end  92  of the collar  22  abuts the end  55  body portion  56  of the control sleeve  18 . 
     The guide assembly  10  may further include at least one washer  108 . In one configuration, the guide assembly includes two washers  108 . As illustrated, in the assembled configuration, the washers  108  may be axially disposed between the counterbore  98  of the collar  22  and the proximal end  32  of the end sleeve  16 . The neck portion  54  of the control sleeve  18  may be concentrically disposed within the washers  108 , such that the retaining ring  59  engages the axial end of the washers  108  and the distal end of the neck portion  54  to prevent axial displacement of the control sleeve  18  relative to the collar  22  and to allow the retaining ring  59  and the control sleeve  18  to rotate relative to the end sleeve  16 . 
     The inner sleeve  24  may extend between a proximal end  112  and a distal end  114  along the longitudinal axis  30 . The inner sleeve  24  may be a generally cylindrical member having a bore  116  extending longitudinally therethrough from the proximal end  112  to the distal end  114 . The proximal end  112  of the inner sleeve  24  may include a generally cylindrical neck portion  118  defining an axial stop surface  120 . The stop surface  120  may be disposed between the proximal end  112  and the distal end  114  of the inner sleeve  24 . The neck portion  118  may include a laterally extending aperture  122 . The distal end  114  of the inner sleeve  24  may include a radially extending flange or lip  124  defining an axial stop surface  126 . 
     In the assembled configuration the inner sleeve  24  may be concentrically disposed within the end sleeve  16 , the control sleeve  18 , the adjustment sleeve  20 , and the collar  22 . The neck portion  118  of the inner sleeve  24  may be disposed within the adjustment sleeve  20  such that the distal end  74  of the adjustment sleeve  20  is disposed adjacent to the stop surface  120  of the inner sleeve  24 . The inner sleeve  24  may be fixed for axial displacement with the adjustment sleeve  20 . Specifically, in one configuration the pin  90  may extend through the adjustment sleeve  20  and at least partially within the aperture  122  of the inner sleeve  24 . 
     In one configuration, the inner sleeve  24  may include a metering portion (not shown) showing distances such as inches, millimeters, centimeters, etc. The metering portion of the inner sleeve  24  may be visible through the aperture  64  of the control sleeve  18 , such that the user can determine the distance by which the drill bit  12  will extend beyond the distal end  34  of the end sleeve  16 . 
     The biasing member  26  may be disposed between the control sleeve  18  and the inner sleeve  24 . In one configuration, the biasing member  26  may be a helical compression spring longitudinally extending between a proximal end  128  and a distal end  130 . The biasing member  26  may be concentrically disposed around the inner sleeve  24 , and concentrically disposed within the counterbore  38  of the end sleeve  16 . The proximal end  128  of the biasing member  26  may be disposed adjacent the distal end  52  of the control sleeve  18 . The distal end  130  of the biasing member  26  may be disposed adjacent the stop surface  126  of the inner sleeve  24 . Accordingly, in the assembled configuration, the biasing member  26  may be operable to bias the inner sleeve  24  and the adjustment sleeve  20  relative to the control sleeve  18 . Specifically, the biasing member  26  may be operable to bias the distal end  114  of the inner sleeve  24  away from the distal end  52  of the control sleeve  18 , and bias the proximal end  72  of the adjustment sleeve  20  in the direction of the distal end  34  of the end sleeve  16 . Accordingly, the biasing member  26  may be operable to bias the pin  90  into engagement with at least one of the notches  70  of the helical slot  66 . 
     The handle assembly  28  may include a collar  132 , a shaft  134 , a handle  136 , and a cap  138 . The collar  132  may define a longitudinally extending bore  140  and an aperture  142 . In an assembled configuration, the control sleeve  18  may be concentrically disposed within the bore  140 , such that the handle assembly  28  can be rotated or otherwise maneuvered independently of the end sleeve  16 . 
     The shaft  134  may extend in a generally arcuate configuration from a proximal end  144  to a distal end  146 . In one configuration, the shaft  134  may be constructed from aluminum to improve the weight and strength characteristics of the shaft  134 . It will also be appreciated that the shaft  134  may be constructed from any other similarly suited material. The proximal end  144  of the shaft  134  may include an externally threaded portion  145 . The distal end  146  of the shaft  134  may be mounted to the collar  132 , and may include an aperture  147 . In one configuration, the aperture  147  of the shaft  134  may be aligned with the aperture  142  of the collar. A pin may be disposed within the aperture  147  and the aperture  142  to secure the shaft  134  to the collar  132 . It will also be appreciated that the shaft  134  may be mounted to the collar  132  using other methods and configurations within the scope of the present teachings. 
     The handle  136  may extend from a proximal end  150  to a distal end  152 . In one configuration, the handle  136  is formed from silicone to allow a user to better grip the handle  136 . It will also be appreciated that the handle  136  may be formed from any other similarly suited material. The proximal end  150  of the handle  136  may include a first internally threaded portion  154 . The distal end  152  of the handle  136  may include a second internally threaded portion  156 . The proximal end  144  of the shaft  134  may be mounted to the handle  136  such that the threaded portion  145  of the shaft  134  is threadably engaged with the second threaded portion  156  of the handle  136 . It will also be appreciated that the handle  136  may be mounted to the shaft  134  using a press-fit engagement, adhesive, or any other suitable technique. 
     The cap  138  may include a head portion  158  and a stem portion  160 . The stem portion  160  may be externally threaded, such that the cap  138  can be mounted to the handle  136  by threadably engaging the stem portion  160  with the threaded portion  154  of the handle. 
     To adjust the depth by which a drill bit  12  extends beyond the distal end  34  of the end sleeve  16 , the user may apply an axial force F1 to the adjustment sleeve  20  to overcome a compressive biasing force F2 of the biasing member  26 , as illustrated in  FIGS. 8 and 8A . The force F1 may cause the proximal end  72  of the control sleeve  72  to travel away from the distal end  34  of the end sleeve  16 , and cause the pin  90  to disengage the notch  70 , such that the pin  90  is disposed within the helical slot  66  of the control sleeve  18 . The user may then rotate the adjustment sleeve  20  about the longitudinal axis  30  relative to the control sleeve  18 , such that the pin  90  traverses the helical slot  66 , and the proximal end  72  of the adjustment sleeve  20  travels in the axial direction relative to the distal end  34  of the end sleeve  16 . To secure the depth by which a drill bit  12  extends beyond the distal end  34  of the end sleeve  16 , the user may release the axial force F1, such that the biasing force F2 causes the pin  90  to travel in the axial direction and into engagement with one of the notches  70 , thus preventing the adjustment sleeve  20  from rotating relative to the control sleeve  18 . 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.