Caps for implants, implant assemblies, and methods of use

An implant assembly can include an implant configured to be coupled to at least one bone part. The implant can include an implant body that defines at least one unsmooth surface. The assembly can further include a cap configured to be coupled to the implant body such that the cap overlies the at least one unsmooth surface. The cap can include a shell that defines a cavity that is configured to receive at least a portion of the implant body such that the shell flexes relative to the implant body as the cavity receives the at least a portion of the implant body to thereby couple the cap to the implant. The cap defines an outer surface that is curved.

BACKGROUND

Medical procedures often times require the implantation of a device into a patient's body. For example, to fix two or more bones relative to each other, bone screws, bone plates, fixation members, or even distractors are coupled to the to two or more bones. Such devices or implants typically have sharp edges that can cause irritation to the surrounding soft tissue such as for example to the surrounding blood vessels, muscles including the tongue, nerves, skin and dura.

SUMMARY

In an embodiment, a cap can be configured to be coupled to an implant having an implant body. The cap can include a cap body that includes a shell having at least one side wall that defines at least a first inner surface and a second inner surface that is spaced from the first inner surface along a first direction. The first and second inner surfaces can at least partially define a cavity that is sized to receive at least a portion of the implant body such that the shell flexes between a first position and a second position as the cavity receives the at least a portion of the implant body. The cap can further include an attachment mechanism that is configured to abut an inner surface of the implant when the shell is in the second position to thereby trap the at least a portion of the implant body within the cavity.

In another embodiment, an implant assembly can include an implant configured to be coupled to at least one bone part. The implant can include an implant body that defines at least one unsmooth surface. The assembly can further include a cap configured to be coupled to the implant body such that the cap overlies the at least one unsmooth surface. The cap can include a shell that defines a cavity that is configured to receive at least a portion of the implant body such that the shell flexes relative to the implant body as the cavity receives the at least a portion of the implant body to thereby couple the cap to the implant. The cap defines an outer surface that is curved.

In another embodiment, a method of fixing a first bone part relative to a second bone part can include the steps of fixing a first bone part relative to a second bone part with an implant that defines a bone facing surface and an opposed outer surface; positioning a cap defining a curved outer surface over the outer surface of the implant, the cap having a shell that defines a cavity, the cap further having at least one attachment member that extends from the shell; and moving the cap toward the implant such that the cavity receives a portion of the implant and until the at least one attachment member abuts the bone facing surface to thereby couple the cap to the implant.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Certain terminology is used in the following description for convenience only and is not limiting. The words “right”, “left”, “lower” and “upper” designate directions in the drawings to which reference is made. The words “proximally” and “distally” refer to directions toward and away from, respectively, the surgeon using the surgical instrument. The words, “anterior”, “posterior”, “superior”, “inferior” and related words and/or phrases designate preferred positions and orientations in the human body to which reference is made and are not meant to be limiting. The terminology includes the above-listed words, derivatives thereof and words of similar import.

Referring toFIGS. 1A-1Dan implant assembly10can include an implant, illustrated as a bone fixation member14that is configured to be coupled to at least one bone part and a cap18that is configured to be coupled to the bone fixation member14. In particular, the bone fixation member14is configured to secure first and second bone parts of a target bone, such as a sternum, that are separated at a fracture location together in a compressed approximated position. As shown inFIGS. 1A and 1B, the bone fixation member14can be substantially configured as a cable tie, and extends horizontally along a longitudinal direction L and a lateral direction A, and vertically along a transverse direction T. The bone fixation member14includes a flexible strap22that is elongate along the longitudinal direction and an implant body that is configured as a locking head26that extends from an end of the strap22along the longitudinal direction L.

The locking head can define an inner surface24such as a bone facing surface, an outer surface25, a slot27that extends through the locking head26from the bone facing surface24to the outer surface25. The locking head can further include at least one locking tooth28that extends into the slot27. The strap22can define a plurality of teeth23that are configured to engage the at least one tooth28of the locking head26as the strap22translates through the slot27. The implant body or locking head26can be substantially box shaped so as to define at least one unsmooth surface30. For example, because the locking head26is substantially box shaped, edges of the locking head can be sharp or otherwise non-rounded. Therefore, it can be said that the locking head26has at least one unsmooth surface30. In the illustrated embodiment, the bone facing surface24is the bottom surface of the locking head26and the at least one unsmooth surface30of the locking head26is the top surface. It should be appreciated, however, that the bone facing surface24can be any surface that faces the bone and that the at least one unsmooth surface30can be any surface on the locking head26. Further, it should be appreciated, that an unsmooth surface30can be any surface that is segmented, or otherwise interrupted, any surface that includes sharp edges, or any surface that includes a protuberance, for example.

With continued reference toFIGS. 1A-1D, the cap18can be configured to be coupled to the locking head26, such that the cap18overlies the locking head or at least the unsmooth surface30to thereby eliminate the unsmooth surface and/or reduce the palpability of the locking head26. Therefore, the cap18can be configured to remove sharp edges from and/or reduce the palpability of the locking head26when coupled to the locking head26. As shown inFIGS. 1A and 1Bthe cap18includes a cap body34that is curved or otherwise rounded so as to reduce irritation that may be caused to the surrounding soft tissue by the locking head26. The cap body34defines a first or upper end38and a second or lower end42that is spaced from the first end38along the transverse direction. The cap body34further includes a cavity46that extends into the lower end42. The cavity46is configured to receive at least a portion of, such as a major portion of the locking head26. It should be appreciated, however, that the cavity46can be configured to receive any locking head, as desired.

As shown inFIG. 1C, the first end38of the cap body34defines an upper surface50and the second end42of the cap body34defines a lower surface54. The cap body34further defines two opposed side surfaces58that merge into the upper and lower surfaces50and54. As shown, the cap body34is curved, or otherwise rounded along the longitudinal direction L and includes a distal body end64and a proximal body end68spaced from the distal body end64along the longitudinal direction L. The cap body34can be curved from a location between the distal and proximal body ends64and68to the proximal body end68. Therefore, the upper surface50is substantially convex along the longitudinal direction L. As shown inFIG. 1D, the upper surface50is curved such that the slope of the upper surface50increases as the upper surface50extends toward the proximal body end68.

As shown inFIGS. 1B-1D, the cap body34can define an outer shell80and an inner shell84disposed within the outer shell80. The inner shell84includes a ceiling70and at least one side wall74that extends down from the first end38and defines at least a first inner surface75aand a second inner surface75bthat is spaced from and substantially faces the first inner surface75aalong a first direction (e.g. the lateral direction) such that the ceiling70and the first and second inner surfaces75aand75bat least partially define the cavity46. In the illustrated embodiment, the at least one side wall74defines a third surface75cthat joins the first surface75ato the second surface75bsuch that the first, second, and third surfaces75a-75care continuous. It should be appreciated, however, that the inner shell84can include three side walls that each defines the respective inner surfaces75a-75c. It should also be appreciated, that the second inner surface75bcan face the first inner surface75asuch that a line that is orthogonal to the second inner surface75aextends toward the first inner surface or at least has a directional component that extends toward the first inner surface. Therefore, the first and second inner surfaces75aand75bcan define planes that are parallel to each other or can define planes that are oblique to each other and still substantially face each other.

As shown inFIG. 1D, the distal end of the cap body34defines an opening78that extends into the cavity46. The ceiling70and the at least one side wall74are configured to cover the locking head26when the locking head26is received within the cavity46, and the opening78is configured to allow the strap22to extend through the opening78when the locking head26is received within the cavity46.

As shown inFIG. 1C, the outer shell80can define an inner surface92and the inner shell84can further define an outer surface96that faces and is spaced apart from the inner surface92along at least a portion of the surfaces92and96. Because inner and outer surfaces92and96of the outer and inner shells80and84, respectively, are spaced from each other, the inner shell84is configured to elastically flex relative to the outer shell80as the cavity46receives the locking head26. That is, the side walls74of the inner shell84are configured to elastically flex outwardly between a first position and a second position as the cavity46receives the locking head26. It should be appreciated, however, that the inner shell84can be configured to be non-flexible. Moreover, it should be appreciated, that the cap body34can be void of the inner shell84and can define an outer shell that defines the cavity46.

With continued reference toFIGS. 1B-1D, the cap18can further include an attachment mechanism that is configured to couple the cap18to the locking head26. In the illustrated embodiment, the attachment mechanism includes at least one, such as a first and a second attachment member100that are configured to couple the cap18to the locking head26. As shown, the attachment mechanism or each attachment member100can be defined by or otherwise extend from the at least one side wall74substantially along the first direction. In the illustrated embodiment, the first and second attachment members100extend toward each other into the cavity46from a location that is proximate to the lower end32and are opposed to each other along the first direction. The attachment members100can each define an abutment surface104that faces the ceiling70of the cavity36such that when the cap18is coupled to the locking head26the abutment surfaces104abut the bone facing surfaces24of the locking head26to thereby trap or otherwise secure the locking head within the cavity46. It should be appreciated, that the attachment members can include other configurations. For example, the attachment members100can define C-clips. Moreover, it should be appreciated that the cap18can include features other than the attachment members100that are configured to couple the cap18to the locking head26. For example, the attachment mechanism can be a surface of the at least one side wall74such that the surface creates a frictional fit with the locking head or the attachment mechanism can be a fixation member such as a needle. Even further, the first and second attachment members100can be configured to abut respective bone facing surfaces of the locking head.

In operation, a bone fixation members14may be placed about the bone segments and of the sternum between adjacent ribs and the strap22can be pulled through the slot27. As the strap22is translated through the slot27of the locking head26the locking teeth28and23can engage to prevent the tension that is induced in the strap22from causing the strap22to back out of the slot27. Once the strap22has reached a maximum desired tension, the free end of the bone fixation member14can be cut off. After the free end is removed, the cap18can be coupled to the locking head26to thereby smooth out the sharp edges of the locking head26.

In another embodiment and in reference toFIGS. 2A-2E, an implant assembly110can include an implant, illustrated as a bone plate114that is configured to be coupled to at least one bone part, a first cap118aand/or a second cap118bthat are both configured to be coupled to the bone plate114. In particular, the bone plate114is configured to secure first and second bone parts that are separated at a fracture location together in a compressed approximated position. The bone plate114can include a plate body126that defines an inner surface124such as a bone facing surface, an opposed outer surface125, and a plurality of bone fixation apertures127that extend through the plate body126from the bone facing surface124to the outer surface125. The plate body126can further include at least one bone fixation element that extends through one of the bone fixation apertures127and into one of the bone parts to thereby couple the bone plate114to the bone part. The plate body126can be substantially box shaped so as to define at least one unsmooth surface130. For example, because the plate body126is substantially box shaped, edges of the plate body126can be sharp or otherwise non-rounded. Therefore, it can be said that the plate body126has at least one unsmooth surface130. Further, the bone fixation element that extends through one of the bone fixation apertures127can also define the at least one unsmooth surface130.

With continued reference toFIGS. 2A-2D, the cap118acan be configured to be coupled to the plate body126, such that the cap118aoverlies the plate body126or at least the unsmooth surface130to thereby eliminate the unsmooth surface and/or reduce the palpability of the plate body126. Therefore, the cap118acan be configured to remove sharp edges from and/or reduce the palpability of the plate body126when coupled to the plate body126. As shown inFIG. 2Athe cap118aincludes a cap body134athat is curved or otherwise rounded so as to reduce irritation that may be caused to the surrounding soft tissue by the plate body126. The cap body134adefines a first or upper end138aand a second or lower end142athat is spaced from the first end138aalong the transverse direction. The cap body134afurther includes a cavity146athat extends into the lower end142a. The cavity146ais configured to receive at least a portion of the plate body126.

As shown inFIG. 2D, the first end138aof the cap body134adefines an upper surface150athat is curved, or otherwise rounded along the lateral direction A and includes a distal body end164aand a proximal body end168aspaced from the distal body end164aalong the longitudinal direction L. The cap body134acan be curved along the lateral direction so as to define a convex outer surface150a. As shown inFIG. 2D, the upper surface150ais curved such that the slope of the upper surface150aincreases as the upper surface150aextends laterally in opposite directions from a centerline of the upper surface150a.

As shown inFIGS. 2B-2D, the cap body134acan define an outer shell180aand an inner shell184adisposed within the outer shell180a. The inner shell184aincludes a ceiling170aand at least two side walls174athat extend down from the first end138aand define at least a first inner surface175aand a second inner surface175bthat is spaced from and substantially faces the first inner surface175aalong a first direction (e.g. the lateral direction) such that the ceiling170aand the first and second inner surfaces175aand175bat least partially define the cavity146a. In the illustrated embodiment, the inner shell184aincludes a first side wall174aand a second side wall174athat is spaced from the first side wall174asuch that the first inner surface175ais parallel to the second inner surface175b. Further, in the illustrated embodiment, the ceiling170adefines a recess171that is configured to receive a portion of a bone fixation element head when the cap118ais coupled to the implant body126over the bone fixation element.

As shown inFIG. 2C, the distal end of the cap body134adefines a first opening178athat extends into the cavity146aand the proximal end of the cap body134adefines a second opening178bthat extends into the cavity146a. The cavity146aand the first and second openings178aand178btogether define a channel179athat extends through the cap body134aalong a second direction (e.g. the longitudinal direction) that is substantially perpendicular to the first direction. The channel179ais configured to receive the plate body so as to cover a portion of the plate body126and the openings178aand178bare configured to allow the plate body126to extend through the openings178aand178bwhen the portion of the plate body126is received within the cavity146aor channel179a. It should be appreciated, that while the first and second side walls174aare each continuous along the second direction, the first and second side walls174acan be segmented along the second direction, as desired.

As shown inFIG. 2D, the outer shell180acan define an inner surface192aand the inner shell184acan further define an outer surface196athat faces and is spaced apart from the inner surface192aalong at least a portion of the surfaces192aand196a. Because inner and outer surfaces192aand196aof the outer and inner shells180aand184a, respectively, are spaced from each other, the inner shell184ais configured to elastically flex relative to the outer shell180aas the cavity146areceives the plate body126. That is, the side walls174aof the inner shell184aare configured to elastically flex outwardly between a first position and a second position as the cavity146areceives the plate body126. It should be appreciated, however, that the inner shell184acan be configured to be non-flexible. Moreover, it should be appreciated, that the cap body134acan be configured such that the outer shell defines the cavity146a.

With continued reference toFIG. 2D, the cap118acan further include an attachment mechanism that is configured to couple the cap118ato the body126. In the illustrated embodiment, the attachment mechanism includes at least one, such as a first and a second attachment member200athat are each configured to capture the cap118ato the body126. As shown, the attachment mechanism or each attachment member200acan be defined by or otherwise extend from the at least one side wall, such as from each of the first and second side walls174asubstantially along the first direction. In the illustrated embodiment, the first and second attachment members200aextend toward each other into the cavity146afrom a location that is proximate to the lower end142aand are opposed to each other along the first direction. The attachment members200acan each define an abutment surface204athat faces the ceiling170aof the cavity146asuch that when the cap118ais coupled to the plate body126the abutment surfaces204aabut the bone facing surface(s)124of the plate body126to thereby trap or otherwise secure the plate body126within the cavity146a. It should be appreciated, that the attachment members can include other configurations. For example, the attachment members200acan define C-clips. Moreover, it should be appreciated that the cap118acan include features other than the attachment members200athat are configured to couple the cap118ato the plate body126. For example, the attachment mechanism can be respective surfaces of the side walls174asuch that the surfaces create a frictional fit with the body.

In the illustrated embodiment, the first and second side walls174aare spaced from each other such that the first and second inner surfaces175aand175babut outer side surfaces208of the implant body126when the cap118ais coupled to the implant body126. In operation, a plate114may be placed on at least two bone parts and secured to the bone parts with respective bone fixation elements. The cap118acan then be coupled to the plate body126to thereby smooth out the sharp edges of the plate body126. The cap118acan be coupled to the implant body126such that the cap118aoverlies the bone fixation element of the implant body126or over a portion of the implant body126between adjacent bone fixation element receiving apertures.

Now in reference toFIGS. 2A, 2B, 2C, and 2E, the cap118bcan be configured to be coupled to the plate body126through one of the bone fixation apertures127, such that the cap118boverlies the plate body126or at least the unsmooth surface130to thereby eliminate the unsmooth surface and/or reduce the palpability of the plate body126. Therefore, the cap118bcan be configured to remove sharp edges from and/or reduce the palpability of the plate body126when coupled to the plate body126. As shown inFIGS. 2A and 2Bthe cap118bincludes a cap body134bthat is curved or otherwise rounded so as to reduce irritation that may be caused to the surrounding soft tissue by the plate body126. The cap body134bdefines a first or upper end138band a second or lower end142bthat is spaced from the first end138balong the transverse direction. The cap body134bfurther includes a cavity146bthat extends into the lower end142b. The cavity146bis configured to receive at least a portion of the plate body126.

As shown inFIG. 2E, the first end138bof the cap body134bdefines an upper surface150bthat is curved, or otherwise rounded along the lateral direction A and includes a distal body end164band a proximal body end168bspaced from the distal body end164balong the longitudinal direction L. The cap body134bcan be curved along the lateral direction so as to define a convex outer surface150b. As shown inFIG. 2E, the upper surface150bis curved such that the slope of the upper surface150bincreases as the upper surface150bextends laterally in opposite directions from a centerline of the upper surface150b.

As shown inFIGS. 2A-2C and 2E, the cap body134bcan define an outer shell180band an inner shell184bdisposed within the outer shell180b. The outer shell184bincludes a ceiling170band the inner shell184bincludes at least one side wall174bthat define at least a first inner surface175cand a second inner surface175dthat is spaced from and substantially faces the first inner surface175calong a first direction (e.g. the lateral direction). As shown inFIG. 2D, the outer shell180bcan define first and second inner surfaces192band the inner shell184bcan further define first and second outer surfaces196bthat face and are spaced apart from the inner surfaces192balong at least a portion of the surfaces192aand196a. The ceiling170b, inner surface192band outer surface196bat least partially define the cavity146b. Because inner and outer surfaces192band196bof the outer and inner shells180band184b, respectively, are spaced from each other, the inner shell184bis configured to elastically flex relative to the outer shell180bas the cavity146breceives the plate body126. That is, the at least one side wall174bof the inner shell184bis configured to elastically flex inwardly between a first position and a second position as the cavity146breceives the plate body126. It should be appreciated, however, that the inner shell184acan be configured to be non-flexible, as desired.

The inner shell184bor at least the at least one side wall174bcan be configured to be inserted through one of the bone fixation apertures127of the plate body126. In the illustrated embodiment, the at least one side wall174bis substantially continuous and is substantially cylindrical in shape. It should be appreciated, however, that the at least one side wall174bis discontinuous and/or has a different shape as desired, so long as the inner shell184bcan be passed through one of the bone fixation apertures127.

As shown inFIG. 2C, the distal end of the cap body134bdefines a first opening178cthat extends into the cavity146band the proximal end of the cap body134bdefines a second opening178dthat extends into the cavity146b. The cavity146band the first and second openings178cand178dtogether define a channel179bthat extends through the cap body134balong a second direction (e.g. the longitudinal direction) that is substantially perpendicular to the first direction. The channel179bis configured to receive the plate body so as to cover a portion of the plate body126and the openings178cand178dare configured to allow the plate body126to extend through the openings178cand178dwhen the portion of the plate body126is received within the cavity146bor channel179b.

With continued reference toFIG. 2E, the cap118bcan further include an attachment mechanism that is configured to couple the cap118bto the body126. In the illustrated embodiment, the attachment mechanism includes at least one, such as a first and a second attachment member200bthat are configured to couple the cap118bto the body126. As shown, the attachment mechanism or each attachment member200bcan be defined by or otherwise extend from the at least one side wall substantially along the first direction. In the illustrated embodiment, the first and second attachment members200bextend away from each other into the cavity146bfrom a location that is proximate to the lower end142band are opposed to each other along the first direction. The attachment members200bcan each define an abutment surface204bthat faces the ceiling170bof the cavity146bsuch that when the cap118bis coupled to the plate body126the abutment surfaces204babut the bone facing surface(s)124of the plate body126to thereby trap or otherwise secure the plate body126within the cavity146b. The first and second attachment members200bcan extend around the side wall so as to define a continuous attachment member. Further the attachment member200bcan be opposed along any direction as desired. It should be appreciated, that the attachment members can include other configurations. For example, the attachment members200bcan define C-clips. Moreover, it should be appreciated that the cap118bcan include features other than the attachment members200bthat are configured to couple the cap118bto the plate body126. For example, the attachment mechanism can be respective surfaces of the side walls174bsuch that the surfaces create a frictional fit with the body or the attachment mechanism can be a fixation member such as a needle. Even further, the first and second attachment members200bcan be configured to abut respective bone facing surfaces of the plate body.

In the illustrated embodiment, and in continued reference toFIG. 2E, the at least one side wall174bis configured such that the outer surface abuts inner surfaces209of the implant body126that define the bone fixation apertures127when the cap118bis coupled to the implant body126. In operation, a plate114may be placed on at least two bone parts and secured to the bone parts with respective bone fixation elements. The cap118bcan then be coupled to the plate body126to thereby smooth out the sharp edges of the plate body126. The cap118bcan be coupled to the implant body126such that the cap118boverlies the bone fixation element aperture with or without a bone fixation element of the implant body126or over a portion of the implant body126between adjacent bone fixation element receiving apertures.

In another embodiment and in reference toFIGS. 3A-3D, an implant assembly310can include an implant, illustrated as a bone fixation element, such as a pedicle screw and fixation rod system314that is configured to be coupled to at least one vertebra and a cap318is configured to be coupled to the system314. In particular, the system314is configured to secure first and second bone parts such as a first and second vertebra. The system314can include a pedicle screw326and a spinal fixation rod325that is secured to the pedicle screw326. The spinal fixation rod325can define an inner surface324such as a bone facing surface and an opposed outer surface321. The pedicle screw326can include a head portion323that defines a rod receiving channel, an engagement portion that extends from the head portion323and is configured to attach to bone, and a set screw327configured to couple to the head portion323so as to secure the spinal fixation rod325within the rod receiving channel. The head portion323and/or the set screw327can define at least one unsmooth surface330. Therefore, it can be said that the pedicle screw and bone fixation rod are an implant body that defines at least one unsmooth surface330. It should be appreciated, that while the spinal fixation rod325defines a bone facing surface that the pedicle screw can also define a bone facing surface of the system314.

With continued reference toFIGS. 3A-3D, the cap318can be configured to be coupled to the system314and in particular to the head portion323of the pedicle screw326and/or to the spinal fixation rod325, such that the cap318overlies the system326or at least the unsmooth surface330to thereby eliminate the unsmooth surface and/or reduce the palpability of the system326. Therefore, the cap318can be configured to remove sharp edges from and/or reduce the palpability of the system326when coupled to the system326. As shown inFIG. 3Athe cap318includes a cap body334that is curved or otherwise rounded so as to reduce irritation that may be caused to the surrounding soft tissue by the system326. The cap body334defines a first or upper end338and a second or lower end342that is spaced from the first end338along the transverse direction. The cap body334further includes a cavity346that extends into the lower end342. The cavity346is configured to receive at least a portion of the system326such as at least a portion of the head portion323and/or the spinal fixation rod325.

As shown inFIG. 3D, the first end338of the cap body334defines an upper surface350that is curved, or otherwise rounded and includes a distal body end364and a proximal body end368spaced from the distal body end364along the longitudinal direction L. The cap body334can be curved or otherwise dome shaped so as to define a convex outer surface350. As shown inFIG. 3C, the upper surface350is curved such that the slope of the upper surface350increases as the upper surface350extends outward from a centerline of the upper surface350.

As shown inFIGS. 3A-3D, the cap body334can define an outer shell380that includes a ceiling370and at least one side wall374that extends down from the first end and defines at least a first inner surface375aand a second inner surface375bthat is spaced from and substantially faces the first inner surface375aalong a first direction (e.g. the lateral direction) such that the ceiling370and the first and second inner surfaces375aand375bat least partially define the cavity346. In the illustrated embodiment, the outer shell380includes a continuous side wall374that is cylindrically shaped such that the first and second inner surfaces375aand375bare continuous with each other so as to be a single surface.

As shown inFIG. 3D, the distal end of the cap body334defines a first opening378athat extends into the cavity346and the proximal end of the cap body334defines a second opening378bthat extends into the cavity346. The cavity346and the first and second openings378aand378btogether define a channel379that extends through the cap body334along a second direction (e.g. the longitudinal direction) that is substantially perpendicular to the first direction. The channel379is substantially cylindrically shaped and is configured to receive the spinal fixation rod325so as to cover a portion of the spinal fixation rod325and at least a portion of the head portion323of the pedicle screw326and the openings378aand378bare configured to allow the spinal fixation rod325to extend through the openings378aand378bwhen the portion of the spinal rod325is received within the cavity346or channel379. It should be appreciated, that while the side wall374is continuous, the side wall374can be segmented, as desired.

As shown inFIG. 3C, the shell380is configured to elastically flex as the cavity346receives the head portion323and/or the rod325. That is, the side wall374is configured to elastically flex outwardly between a first position and a second position as the cavity346receives the head portion323and/or the rod325.

With continued reference toFIG. 3D, the cap318can further include an attachment mechanism that is configured to couple the cap318to the system314. In the illustrated embodiment, the attachment mechanism includes at least one, such as a first and a second attachment member400that are configured to couple the cap318to the system. As shown, the attachment mechanism or each attachment member400can be defined by or otherwise extend from the at least one side wall substantially along the first direction. In the illustrated embodiment, the first and second attachment members400extend toward each other into the cavity346and are opposed to each other along the first direction. The attachment members400can each define an abutment surface404that faces the ceiling370of the cavity346such that when the cap318is coupled to the system314the abutment surfaces404abut the bone facing surface(s)324of the spinal fixation rod325to thereby trap or otherwise secure the head portion323and spinal fixation rod325within the cavity346. It should be appreciated, that the attachment members can include other configurations. For example, the attachment members400can define C-clips. Moreover, it should be appreciated that the cap318can include features other than the attachment members400that are configured to couple the cap318to the system314. For example, the attachment mechanism can be respective surfaces of the side walls374such that the surfaces create a frictional fit with the system or the attachment mechanism can be a fixation member such as a needle. Even further, the first and second attachment members400can be configured to abut respective bone facing surfaces of the head portion323.

In operation, a pedicle screw may be attached to a vertebra and a spinal fixation rod mad be attached to the pedicle screw to thereby form a spine fixation system314. The cap318can then be coupled to the pedicle screw and/or the spinal fixation rod to thereby smooth out the sharp edges of the pedicle screw. The cap318can be coupled to the system314such that the cap318overlies the head portion of the pedicle screw, for example as shown inFIGS. 3B-3D.

In another embodiment and in reference toFIGS. 4A-4E, an implant assembly410can include an implant, illustrated as a distractor, such as a palatal distractor414that is configured to be coupled to at least two bone parts and a cap418that is configured to be coupled to the distractor414. In particular, the distractor414is configured to couple to first and second bone parts so that the bone parts can be moved away from each other using the distractor414. For example, the distractor414can be configured to expand an individual's maxilla. It should be appreciated, however, that the distractor414can be configured to expand any bone as desired.

As shown inFIGS. 4A-4C, the distractor414can include a distractor body426, a first coupling member425athat extends from a first end of the distractor body426and a second coupling member425bthat extends from a second opposed end of the distractor body426. The first and second coupling members425aand425bare configured to be attached to respective bone parts. The distractor body426is configured to move at least one of the first and second coupling members425aand425baway from the other so as to cause at least one of the bone parts to move away from the other. The distractor body426can define an inner surface424such as a tissue facing surface and an opposed outer surface425. The distractor body426can further define at least one unsmooth surface430.

With continued reference toFIGS. 4A-4E, the cap418can be configured to be coupled to the distractor414and in particular to the distractor body426, such that the cap418overlies the distractor body426or at least the unsmooth surface430to thereby eliminate the unsmooth surface and/or reduce the palpability of the distractor body426. Therefore, the cap418can be configured to remove sharp edges from and/or reduce the palpability of the distractor body426when coupled to the distractor body426. As shown inFIGS. 4A and 4Bthe cap418includes a cap body434that is curved or otherwise rounded so as to reduce irritation that may be caused to the surrounding soft tissue (e.g. a tongue) by the distractor body426. The cap body434defines a first or upper end438and a second or lower end442that is spaced from the first end438along the transverse direction. The cap body434further includes a cavity446that extends into the lower end442. The cavity446is configured to receive at least a portion of the distractor body426.

As shown inFIG. 4B, the first end438of the cap body434defines an upper surface450that is curved, or otherwise rounded and includes a distal body end464and a proximal body end468spaced from the distal body end464along the longitudinal direction L. The cap body434can be curved or otherwise rounded along the lateral direction so as to define a convex outer surface450. As shown inFIG. 4E, the upper surface450is curved such that the slope of the upper surface450increases as the upper surface450extends outward from a centerline of the upper surface450.

As shown inFIGS. 4B-4E, the cap body434can define an outer shell480that includes a ceiling470and at least one side wall474that extends from the first end438and defines at least a first inner surface475aand a second inner surface475bthat is spaced from and substantially faces the first inner surface475aalong a first direction (e.g. the lateral direction) such that the ceiling470and the first and second inner surfaces475aand475bat least partially define the cavity446. In the illustrated embodiment, the outer shell480includes first and second side walls474that are parallel to each other and opposed to each other along the first direction such that the first and second inner surfaces475aand475bare parallel to each other and opposed to each other along the first direction.

As shown inFIG. 4C, the distal end of the cap body434defines a first opening478athat extends into the cavity446and the proximal end of the cap body434defines a second opening478bthat extends into the cavity446. The cavity446and the first and second openings478aand478btogether define a channel479that extends through the cap body434along a second direction (e.g. the longitudinal direction) that is substantially perpendicular to the first direction. The channel479is substantially cylindrically shaped and is configured to receive the distractor body426so as to cover a portion of the distractor body426and the openings478aand478bare configured to allow the first and second coupling members425aand425bto extend through the openings478aand478bwhen the portion of the distractor body426is received within the cavity446or channel479.

As shown inFIG. 4C, the shell480is configured to elastically flex as the cavity446receives the distractor body426. That is, the side walls474are configured to elastically flex outwardly between a first position and a second position as the cavity446receives the distractor body426.

With continued reference toFIG. 4C, the cap418can further include an attachment mechanism that is configured to couple the cap418to the distractor414. In the illustrated embodiment, the attachment mechanism includes at least one, such as first, second, third, and fourth attachment members500that are configured to couple the cap418to the distractor. As shown, the attachment mechanism or each attachment member500can be defined by or otherwise extend from the at least one side wall substantially along the first direction. In the illustrated embodiment, the first and second, and the third and fourth attachment members500extend toward each other into the cavity446and are opposed to each other along the first direction. The attachment members500can each define an abutment surface504that faces the ceiling470of the cavity446such that when the cap418is coupled to the distractor414the abutment surfaces504abut the inner surface(s)424of the distractor body426to thereby trap or otherwise secure the distractor body426within the cavity446. It should be appreciated, that the attachment members can include other configurations. For example, the attachment members500can define C-clips. Moreover, it should be appreciated that the cap418can include features other than the attachment members500that are configured to couple the cap418to the distractor414. For example, the attachment mechanism can be respective surfaces of the side walls474such that the surfaces create a frictional fit with the system or the attachment mechanism can be a fixation member such as a needle. Even further, the first and second attachment members500can be configured to abut respective inner surfaces of the distractor body426.

In operation, a distractor414may be attached to a pair of palatal bone portions. The cap418can then be coupled to the distractor414to thereby smooth out the sharp edges of the distractor414. The cap418can be coupled to the distractor414such that the cap418overlies the distractor body426, for example as shown inFIGS. 4B-4E.

In another embodiment and in reference toFIGS. 5A and 5B, an implant assembly510can include a cap518that is configured to be coupled to an aperture519defined by an anatomical structure520such as a clamp member of a cranial clamp as illustrated. In particular the cap518can be configured to be coupled to the implant520through an aperture519, such that the cap518overlies the aperture519or at least an unsmooth surface of the implant520to thereby eliminate the unsmooth surface and/or reduce the palpability of the implant. Therefore, the cap518can be configured to remove sharp edges from and/or reduce the palpability of the implant when coupled to the implant. As shown inFIG. 5Bthe cap518includes a cap body534that is curved or otherwise rounded so as to correspond to the curved surface of the implant520and thereby reduce irritation that may be caused to the surrounding soft tissue by the implant520. The cap body534defines a first or upper end538and a second or lower end542that is spaced from the first end538along the transverse direction. It should be appreciated that the cap518can be further configured to couple to an aperture defined by a bone such that the cap518overlies the bone when coupled to the bone. For example, cap518can be configured to engage an aperture defined by the bone to thereby couple the cap518to the bone.

As shown inFIG. 5B, the first end538of the cap body534defines an upper surface550that is curved, or otherwise rounded so as to define a convex outer surface550. The cap body534can define an outer shell580and an inner shell584disposed within the outer shell580. The outer shell580includes a ceiling570that substantially corresponds to the outer surface of the implant520and the inner shell584includes at least one side wall574that define at least a first inner surface575aand a second inner surface575bthat is spaced from and substantially faces the first inner surface575aalong a first direction (e.g. the lateral direction). As shown inFIG. 5B, the inner shell584can further define an outer surface596. Because the inner surfaces575aand575bare spaced from each other, the inner shell584is configured to elastically flex relative to the outer shell580when the inner shell584is received by the aperture519. That is, the at least one side wall574of the inner shell584is configured to elastically flex inwardly between a first position and a second position as the inner shell584is received by the aperture519. It should be appreciated, however, that the inner shell584can be configured to be non-flexible, as desired.

The inner shell584or at least the at least one side wall574can be configured to be inserted through one of the apertures of the implant520or into the aperture of the bone. In the illustrated embodiment, the at least one side wall574is substantially continuous and is substantially cylindrical in shape. It should be appreciated, however, that the at least one side wall574is discontinuous and/or has a different shape as desired, so long as the inner shell584can be passed through a aperture in the implant or bone.

With continued reference toFIG. 5B, the cap518can further include an attachment mechanism that is configured to couple the cap518to the implant or bone. In the illustrated embodiment, the attachment mechanism includes at least one, such as a first and a second attachment member600that are configured to couple the cap518to the implant or bone. As shown, the attachment mechanism or attachment members600can be defined by or otherwise extend from the at least one side wall and can be substantially continuous as the attachment member extends around the side wall. Therefore, it can be said that at least a portion of the at least one attachment member600extends away from another at least a portion of the at least one attachment member600and the at least a portions of the attachment member600are opposed to each other along the first direction. The attachment member600can be configured to provide an interference fit with the implant520when the inner shell584is received by the aperture519as illustrated inFIG. 5B. It should be appreciated, however, that the attachment member600can be configured to define an abutment surface that is configured to abut an inner surface of the implant520. Further it should be appreciated that the attachment mechanism can be an external surface of the side wall574such that the external surface creates a frictional fit with the bone or implant.

While the foregoing description and drawings represent the preferred embodiments of the present invention, it will be understood that various additions, modifications, combinations and/or substitutions may be made therein without departing from the spirit and scope of the invention as defined in the accompanying claims. In particular, it will be clear to those skilled in the art that the invention may be embodied in other specific forms, structures, arrangements, proportions, and with other elements, materials, and components, without departing from the spirit or essential characteristics thereof. One skilled in the art will appreciate that the invention may be used with many modifications of structure, arrangement, proportions, materials, and components, which are particularly adapted to specific environments and operative requirements without departing from the principles of the invention. In addition, features described herein may be used singularly or in combination with other features. For example, features described in connection with one embodiment may be used and/or interchanged with features described in another embodiment. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and not limited to the foregoing description.

It will be appreciated by those skilled in the art that various modifications and alterations of the invention can be made without departing from the broad scope of the appended claims. Some of these have been discussed above and others will be apparent to those skilled in the art.