Bone peg having improved extraction

A bone peg configured for cooperation with a threaded aperture on a bone plate for use in stabilizing a fracture of a bone can include a head portion and a shaft portion. The head portion can have a head threaded portion that incorporates head threads having a first pitch. The shaft portion can extend from the head portion to a distal end of the bone peg. The shaft portion can include (i) a shaft threaded portion that incorporates shaft threads having a second pitch, (ii) a first unthreaded portion and (iii) a second unthreaded portion. The shaft threaded portion is disposed intermediate the first and second unthreaded portions. The first unthreaded portion axially offsets the head threaded portion from the shaft threaded portion.

FIELD

The present disclosure relates generally to bone plating systems and, more particularly, to fixation devices and techniques for fixing a bone plate relative to bone with a bone peg having a thread configuration that facilitates improved removal of the bone peg from the bone.

BACKGROUND

In some instances it may be desirable to fix a bone plate to a proximal humerus such as to stabilize a fracture. The proximal humerus generally lacks typical bone density and has a sponge-like quality. In this regard, it is typical to use smooth pegs in combination with the bone plate to provide subchondral support to compensate for the insufficient cancellous material. Furthermore, such pegs are usually driven into the bone at divergent angles to prevent migration of the bone and plate once all the pegs have been implanted. In some instances the pegs may require removal due to improper peg measurement or surgical revision of the implant. Many times it is difficult to withdraw the peg from the bone and the head of the peg often stays submerged within the hole of the plate. A need exists in the art for a peg that allows for easier withdrawal from the bone and plate.

SUMMARY

A bone peg configured for cooperation with a threaded aperture on a bone plate for use in stabilizing a fracture of a bone can include a head portion and a shaft portion. The head portion can have a head threaded portion that incorporates head threads having a first pitch. The shaft portion can extend from the head portion to a distal end of the bone peg. The shaft portion can include (i) a shaft threaded portion that incorporates shaft threads having a second pitch, (ii) a first unthreaded portion and (iii) a second unthreaded portion. The shaft threaded portion is disposed intermediate the first and second unthreaded portions. The first unthreaded portion axially offsets the head threaded portion from the shaft threaded portion. The first and second pitches can be equivalent whereby the head threaded portion and the shaft threaded portion threadably advance along the threaded aperture of the bone plate and the bone, respectively in a synchronized manner.

According to additional features, the head threads define a first thread start and the shaft threads define a second thread start. The second thread start can be configured to initially mate with the bone at a first time. The first thread start can be configured to initially mate with the threaded aperture on the bone plate at a second time. The first time can occur before the second time when advancing the bone peg through the bone plate and into the bone. The shaft threads can maintain contact with the bone subsequent to the head threads clearing the threaded aperture of the bone plate during withdrawal of the bone peg from the bone.

According to additional features, the head portion tapers from an upper peripheral rim toward the shaft portion. The head portion can further include a tool engaging feature. The tool engaging feature can comprise a driver engagement socket. The head threads can be triple lead. The shaft threads can be triple lead. The head threaded portion can extend a first axial distance along the shaft portion. The first unthreaded shaft portion can extend a second axial distance along the shaft portion. The first and second axial distances are substantially equivalent. The first and second axial distances can be distinct by between 10 percent and 20 percent. The shaft threaded portion can extend a third axial distance along the shaft portion. The third axial distance can be between 15 percent and 25 percent longer than the first axial distance.

A bone plating system configured for stabilizing a fracture of a bone and constructed in accordance to one example of the present disclosure includes a bone peg and a bone plate. The bone peg can include a head portion and a shaft portion. The head portion can have a head threaded portion that incorporates head threads having a first pitch. The shaft portion can extend from the head portion to a distal end of the bone peg. The shaft portion can include (i) a shaft threaded portion that incorporates shaft threads having a second pitch, (ii) a first unthreaded portion and (iii) a second unthreaded portion. The shaft threaded portion is disposed intermediate the first and second unthreaded portions. The first unthreaded portion can axially offset the head threaded portion from the shaft threaded portion. The bone plate can include a plate body, a hole and a plate threaded portion. The plate body can have an upper surface and a lower surface. The hole can be defined through the plate body from the upper surface to the lower surface. The plate threaded portion can be defined by the plate body at the hole. The first and second pitches are equivalent whereby the head threaded portion and the shaft threaded portion threadably advance along the plate threaded portion of the bone plate and the bone, respectively in a synchronized manner.

According to other features, the head threads define a first thread start and the shaft threads define a second thread start. The second thread start can be configured to initially mate with the bone at a first time. The first thread start can be configured to initially mate with the threaded aperture on the bone plate at a second time. The first time can occur before the second time when advancing the bone peg through the bone plate and into the bone. The shaft threads can maintain contact with the bone subsequent to the head threads clearing the threaded aperture of the bone plate during withdrawal of the bone peg from the bone.

According to still additional features, the head portion tapers from an upper peripheral rim toward the shaft portion. The head portion can further include a tool engaging feature. The tool engaging feature can comprise a driver engagement socket. The head threads can be triple lead. The shaft threads can be triple lead. The head threaded portion can extend a first axial distance along the shaft portion. The first unthreaded shaft portion can extend a second axial distance along the shaft portion. The first and second axial distances are substantially equivalent. The first and second axial distances can be distinct by between 10 percent and 20 percent. The shaft threaded portion can extend a third axial distance along the shaft portion. The third axial distance can be between 15 percent and 25 percent longer than the first axial distance.

A method of stabilizing a fracture of a bone using a bone plate and a bone peg can include engaging a bone peg that extends through a threaded aperture in the bone plate. The bone peg includes (A) a head portion having head threads that define a first thread start, and (B) a shaft portion having (i) a shaft threaded portion that incorporates shaft threads having a second thread start, (ii) a first unthreaded portion and (iii) a second unthreaded portion. The shaft threaded portion is disposed intermediate the first and second unthreaded portions. The first unthreaded portion axially offsets the head threaded portion from the shaft threaded portion. The bone peg is withdrawn from the bone wherein the shaft threads maintain contact with the bone subsequent to the head threads clearing the threaded aperture of the bone plate.

According to other features, engaging the bone peg can further include engaging a tool engaging feature configured on the head portion. Prior to withdrawing the bone peg, the bone peg is advanced through the threaded aperture of the bone plate and into the bone. Advancing comprises advancing the bone peg into the bone wherein the second thread start initially mates with the bone at a first time. The bone peg is further advanced into the bone. The second thread start initially mates with a threaded aperture on the bone plate subsequent to the first time.

Further areas of applicability of the present disclosure will become apparent from the description provided hereinafter. 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.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. Examples 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, systems and/or methods, to provide a thorough understanding of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that examples shown herein may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure.

The present teachings provide a bone peg and related bone plate system and methods for using the same to facilitate bone fixation and healing. The particular examples discussed herein relate to fixation or stabilization of a fracture on a distal humerus however they are not so limited. In this regard, the present teachings may be applicable to fixation of any bone or bones. In an exemplary aspect, the bone peg and related bone plate system can be utilized for fracture fixation, fusion of two adjacent bone segments (e.g., joint fusion), and/or for stabilization/reconstruction of a bone or bone segments, including in connection with an osteotomy or the like. In this regard, the bone peg and related bone plating system discussed herein will be referred to as fixation devices and it will be understood that such fixation devices can perform a stabilization function as well as a fixation function between bone segments, a fusion function between bone segments and/or reconstruction of a bone or bone segments.

While the particular discussion and examples used herein use the term “bone peg”, the same may be used to refer to a bone screw, a bone fastener and the like. In this regard, the term “bone peg” has been used in an exemplary manner and the teachings herein may be similarly applied to a bone screw, a bone fastener or other device that cooperates with a bone plate. As used herein, “bone segments” can refer to two segments of the same bone (e.g., relative to a fracture line or osteotomy) or adjacent bones (e.g., of a joint). Further, the discussion herein can be utilized for fixation, fusion and/or reconstruction/repair of various different small bones and/or joints, such as in the arm, leg, hand, foot or elsewhere in the anatomy.

With initial reference toFIGS. 1-4, an exemplary bone plating system generally identified at reference numeral10(FIG. 4) includes a series of bone pegs12and a bone plate14. As will be discussed in greater detail below, the bone plate system10can, in one exemplary implementation, provide for stabilization of bone segments of a proximal humerus or bone16(FIG. 4).

With particular reference now toFIGS. 1 and 2, the bone peg12will be further described. The bone peg12can generally extend between a proximal end18and a distal end20. The bone peg12can include a head portion22and a shaft portion24. The head portion22can have a head threaded portion30that incorporates threads32having a first pitch. In the example shown, the threads32can be in the form of a triple lead right-hand helical thread. The threads32are collectively defined between a thread start34and a thread end38. The head portion22can be spherically shaped and can generally taper from an upper spherical rim40toward the shaft portion24. The head portion22can include a tool engaging feature42formed thereon. The tool engaging feature42of the example shown is a driver engagement socket44. The driver engagement socket44is in the form of a hexagonal profile for mating with a corresponding driver or insertion tool. Other configurations are contemplated.

The shaft portion24can generally extend from the head portion22to the distal end20of the bone peg12. The shaft portion24includes a shaft threaded portion50, a first unthreaded portion52and a second unthreaded portion54. The shaft threaded portion50can incorporate shaft threads60thereon having a second pitch. The shaft threads60can be in the form of a triple lead right-hand helical thread. The shaft threaded portion50is disposed intermediate the first unthreaded portion52and the second unthreaded portion54. The shaft threads60extend between a thread start62and a thread end64(seeFIG. 6). The first unthreaded portion52axially offsets the head threaded portion30from the shaft threaded portion50. In one example, and as will become appreciated from the following discussion, the first and second pitches are equivalent whereby the head threaded portion30and the shaft threaded portion50threadably advance along a threaded aperture of the bone plate14and the bone16in a synchronized manner.

With particular reference now toFIGS. 3 and 4the exemplary bone plate14constructed according to one example of the present disclosure will be described. The bone plate14can generally include a plate body70having an upper surface72and a lower surface74. The bone plate14can include a plate hole80defined through the plate body70from the upper surface72to the lower surface74. A plate threaded portion or threaded aperture82can be defined by the plate body70at the plate hole80. It will be appreciated that the bone plate14may have a plurality of plate holes80having plate threaded portions82defined thereon however the discussion herein will continue with reference to a single plate hole80.

While the bone plate14shown in the example is generally contoured in one form specific to mating with the proximal humerus16, the bone plate14may be contoured differently for mating with other long bones such as a distal radius. Furthermore, the bone plate14may be generally flat. Regardless, it will become apparent to those skilled in the art that the present teachings are also suitable for various other applications in which surgical repair of a bone with a plate and associated fastener is desired. The bone plate14may be constructed of any suitable biocompatible material. One exemplary material is titanium alloy such as Ti6Al4V. Other materials having suitable strength characteristics such as, but not limited to, stainless steel may be similarly used.

With particular reference now toFIGS. 5 and 6, various features of the bone peg12and bone plating system10will be further described. In some instances it may be desirable to remove a bone peg10due to various reasons such as improper measurement of the bone peg12or surgical revision of the implant. Prior art bone pegs do not incorporate threads along the shaft. In this regard, once the head threads lose contact with the corresponding threads of the bone plate during withdrawal, the bone peg cannot be further propelled out of the bone simply by rotating the bone peg. In this situation it may become necessary to grasp the head of the bone peg and pull the bone peg away from the bone and bone plate. Sometimes however this is difficult to gain sufficient access to the head because the head of the bone peg may still be too far down into the plate hole to sufficiently grasp.

The bone peg12according to the present disclosure allows for engagement of the shaft threads60with proximal cortical bone16A even after the head threads32have cleared the threaded aperture82. As a result, further rotation of the bone peg12(in a withdrawal direction) causes the shaft threads60to further advance along the proximal cortical bone16A allowing the head portion22of the bone peg12to extend proud and substantially out of the plate hole80for grasping.

As identified above and shown in the Figures, the head threads32and the shaft threads60are not continuous. The gap between the head threads32and the shaft threads60at the first unthreaded shaft portion52locates within the plate body70of the bone plate14and does not engage with the bone plate14or the bone16. The shaft threads60of the shaft portion24extend distally enough to extend beyond the plate body70of the bone plate14and also ensure adequate engagement with the cortical bone16A.

The pitch of the head threads32and the shaft threads60are equivalent. In this way, the head threaded portion30and the shaft threaded portion50threadably advance along the threaded aperture82of the bone plate14in a synchronized manner. During advancement of the bone peg12into the bone16, the thread start62of the shaft threads60initially mates with the proximal cortical bone16A prior to the thread start34of the head threads32. In this regard, the shaft threads60can threadably engage the bone16without the head threads32engaged to the threaded aperture82of the bone plate14.

With reference now toFIG. 6, exemplary dimensions of the bone peg12will be described. The bone peg12can extend an axial length78between the proximal end18and the distal end20. The head threaded portion30extends a first axial distance80along the shaft portion24. The first unthreaded shaft portion52extends a second axial distance82along the shaft portion24. The shaft threaded portion50extends a third axial distance84along the shaft portion24. An axial distance86is provided from the proximal end18of the bone peg12to the thread start62of the shaft threads60. The axial distance86can be 8.00 mm. The axial distance86can have a tolerance of plus or minus 0.25 mm. The axial length78can be 30.00 mm. The axial length78can have a tolerance of plus or minus 0.25 mm. The first axial distance80can be 2.66 mm. The second axial distance82can be 2.34 mm. Third axial distance84can be 3.00 mm. The first and second unthreaded portions52and54can have a diameter88. The diameter88can be 3.20 mm. In one configuration, the first and second axial distances80and82are substantially equivalent. In one example, the first and second axial distances can be distinct by between 10 percent and 20 percent. In one configuration, the third axial distance84is between 15 percent and 25 percent longer than the first axial distance80. It will be appreciated that other dimensions may be used within the scope of the present disclosure.

While one or more specific examples or aspects have been described and illustrated, it will be understood by those skilled in the art that various changes may be made and equivalence may be substituted for elements thereof without departing from the scope of the present teachings as defined in the claims. Furthermore, the mixing and matching of features, elements and/or functions between various examples may be expressly contemplated herein so that one skilled in the art would appreciate from the present teachings that features, elements and/or functions of one example may be incorporated into another example as appropriate, unless described otherwise above. Moreover, many modifications may be made to adapt a particular situation or material to the present teachings without departing from the essential scope thereof.