US20030125750A1 - Spring loaded fixation element insertion device - Google Patents

Abstract

The invention relates to a device for attaching fixation elements to bone, having a longitudinal member with a channel extending therein adapted for receiving at least one fixation element. A shaft extends within the channel and is positioned coaxially within at least a portion of the longitudinal member and at least a portion of the shaft is retained within the longitudinal member and a distal end of the shaft is configured and adapted to contact at least a portion of the fixation element received within the longitudinal member. A spring is positioned adjacent the shaft for resiliently biasing the shaft in an axial direction and the shaft is moveable with respect to the longitudinal member to drive the fixation element into bone.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• Priority of Provisional Application No. 60/330,977, filed on Nov. 5, 2001 is claimed under 35 U.S.C. §119 and priority of U.S. patent application Ser. No. 09/866,841, filed on May 30, 2001 and PCT Application No. PCT/US02/16656, filed on May 28, 2002 is claimed under 35 U.S.C. §120, the entire contents of which are incorporated by reference.[0001]
FIELD OF THE INVENTION
• The present invention relates to a device for the storage and dispensing of osteosynthetic fixation elements, and in particular to a device for attaching fixation elements to bone.[0002]
BACKGROUND OF INVENTION
• In the surgical treatment of fractures in the maxillofacial area, as well as fractures of the foot and hand, a trend toward preferring ever-smaller implants can clearly be noted. The reason for this is the generally increased understanding of the biomechanical bases of osteosynthesis. In the field of treating maxillofacial fractures, more attention can be paid to the cosmetic results of osteosynthesis, thanks to the miniaturization of implants. In the field of hand surgery, restrictions on movement in the area of the fingers can be avoided. In this regard, smaller osteosynthetic implants in the fingers can be placed under the tendons. In the case of an implant with a large cross-section, the tendons need no longer be extended to their full length.[0003]
• The dimensions of some smaller implants (screws, plates and tacks) are in the range of about 0.8 mm to about 2.0 mm. Problems in the area of packaging, storage and manipulation during surgery arise due to this miniaturization. Handling in the operating room, particularly in the maxillofacial area, has proved difficult. Depending on the degree of severity of the fracture or correction, up to 40 bone fixation elements, such as tacks or screws, may be required. These screws must be taken individually by the operating room nurse from a so-called screw rack, checked for length, placed on a screwdriver and given to the surgeon. The surgeon must, in turn, insert them through the osteosynthesis plate into pre-drilled screw holes. During the transfer of the screw and the attempted insertion of the screw, it often falls off the screwdriver, into the wound or onto the operating room floor. The attempt to find a lost screw is often excessively time-consuming, given their dimensions and extends the time spent in surgery. The frequent loss of screws in the operating room, and during packing and sterilization, causes unnecessary costs for the hospital. Thus, it is desirable to have a simple device that can be operated with one hand, thereby freeing the operator's other hand to align the fixation element or perform other tasks[0004]
• An additional problem in dealing with mini-screws arises during their implantation. After the surgeon has selected the osteosynthesis plate proper for the fracture in question, a plate is positioned over the fracture. A hole is then drilled for the screw (0.5-1.5 mm diameter) through one of the plate holes. Commonly, problems arise in controlling the amount of force applied during the insertion of the screw and or tack. For example, if a surgeon is required to insert a screw or tack with manual force, the manula force could be transmitted to the surrounding bone, which could bend thin and/or flexible bone in young patients.[0005]
• Also, problems such as surgical gloves tearing or hand pinching can arise if the insertion device has parts that move externally during the firing of the device. Thus, a need exists for an insertion device that minimizes the manual force exertion required and to minimize the gross forces applied to the surrounding bone during insertion.[0006]
SUMMARY OF INVENTION
• The present invention relates to a device for attaching fixation elements to bone, including a longitudinal member extending along a longitudinal axis from a proximal end to a distal end and having a channel extending therein adapted for receiving at least one fixation element. A shaft extends within the channel and is positioned coaxially within at least a portion of the longitudinal member and at least a portion of the shaft is retained within the longitudinal member and a distal end configured and adapted to contact at least a portion of the fixation element received within the longitudinal member. A spring is positioned adjacent the shaft for resiliently biasing the shaft in an axial direction and the shaft is moveable with respect to the longitudinal member to drive the fixation element into bone.[0007]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a partially transparent elevated view of one embodiment of an insertion device according to the present invention;[0008]
• FIG. 2 is an elevated view of a fixation element for use with the insertion device of FIG. 1;[0009]
• FIGS.[0010]3-4 illustrate the placement of a fixation element within a pre-drilled hole in bone;
• FIG. 5 is a partially transparent elevated view of another embodiment of an insertion device;[0011]
• FIG. 6 a partial elevated view of the device of FIG. 5;[0012]
• FIG. 7 is a partially transparent elevated view of another embodiment of an insertion device;[0013]
• FIG. 8 is a cross-sectional view of the embodiment of FIG. 7;[0014]
• FIG. 9 is a partial cross-sectional view of a portion A of the device of FIG. 8;[0015]
• FIG. 10 is an elevated view of another embodiment of an insertion device; and[0016]
• FIG.[0017]11 is an elevated view of a cam member of the device of FIG. 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• Referring to FIG. 1, a preferred fixation[0018]element insertion device10 according to the present invention generally includes a longitudinal member extending along alongitudinal axis12 from aproximal end14 to adistal end16 and having achannel18 extending therein. The insertion device is preferably used to drive an osteosynthetic fixation element, such as a resorbable tack, into bone tissue. Channel18 is configured and dimensioned to receive at least one fixation element for storage, transport, dispensing, and or insertion into bone.
• Referring to FIG. 2, one preferred fixation element compatible with[0019]insertion device10 comprises atack20 having ashaft22 integral with ahead24 at a proximal end thereof. The distal end ofshaft22 has aconical nose26 to facilitate the insertion oftack20 into bone tissue. A plurality ofcircular ribs28 extend radially from the exterior ofshaft22 to prevent the removal of the tack from the bone tissue after it has been inserted.Head24 has an outer diameter greater than the diameter ofshaft22 and contacts or rests against the bone or bone plate when the tack is inserted into bone tissue. In the preferred embodiment, the tack is made from a resorbable material so that it remains in the bone tissue temporarily and is absorbed by the body. In alternate embodiments,tack20 can have numerously different configurations and dimensions. Also, different types of fixation elements altogether can be used withinsertion device10. For example, biocompatible screws, nails, anchors, rivets, or other similar implants can also be inserted usinginsertion device10.
• Referring again to FIG. 1,[0020]insertion device10 has ahandle30 at the proximal end that is configured to conform to the shape of a person's hand or palm for easily gripping the device and anapplicator extension32 for holding and dispensing the fixation element. Acentral channel70 extends withinhandle30 and throughextension32 and is in communication withchannel18 atdistal end16.Channel18 generally comprises a socket defined at thedistal end16 and anelongate applicator extension32 extends betweendistal end16 and handle30.Extension32 can be a unitary extension or can include multiple parts. Socket orchannel18 fits about the proximal end offixation element20 to holdelement20 ininsertion device10 by an interference or friction fit. In the embodiment of FIG. 1, anindividual tack20 can be held atdistal end16 andhead24 oftack20 is preferably held within the socket orchannel18 while theshaft22 oftack20 projects outside thereof, as shown in FIG. 3. At the distal end ofextension32 is a pronged tip34 for retaining a fixation element. Pronged tip34 is generally flexible and when the distal end ofextension32 is pressed, the prongs34 ofsleeve32 flex around the head of a fixation element to pick up and retain the element. In this way, it is possible to pick up a relatively small fixation element in a simple, single action.
• A shaft member[0021]36 and a firing spring38 are housed withincentral channel40. Shaft member36 extends longitudinally withinhandle30 andextension32 and is preferably moveable alongaxis12 with respect to handle30 andextension32. Firing spring38 is positioned at the proximal end ofhandle30 and is compressible between a force adjustment dial39 atproximal end14 and a proximal end of shaft member36, biasing shaft member36 in the distal direction. Shaft36 is generally cylindrical and includes abase portion42 that slidingly engages the interior ofchannel40 withinhandle30, a mid-section44 having a smaller diameter thanbase portion42, and a tip portion46 having a smaller diameter than mid-section44. A first shoulder43 is positioned at the transition ofbase portion42 and mid-section44 and a second shoulder45 is positioned at the transition of mid-section44 and tip portion46.
• Shaft[0022]36 is moveable from a loaded position (shown in FIG. 1) to an unloaded position for inserting a fixation element into bone. An activation button48 extends withinchannel40 for activating the movement of shaft36 from a loaded position to an unloaded position. Button48 is positioned along a portion ofhandle30 and partially extends withinchannel40 for engaging shaft36. Referring to FIG. 1, when shaft36 is in the loaded position ledge49 at the proximal end of button48 engages second shoulder45 preventing shaft36 from moving in the distal direction or to the unloaded position. When button48 is depressed by an operator, ledge49 is moved out of engagement with shoulder45, thereby permitting shaft36 to move in the distal direction under the force exerted by firing spring38 on shaft36. As a result, tip portion46 of shaft36 is advanced in the distal direction to force fixation element out ofextension32 and shaft36 is moved to an unloaded position.
• In a preferred embodiment, button[0023]48 is pivotably positioned about a pin47 and the distal portion of button48 is biased radially outward by aspring50 so that ledge49 at the proximal portion of button48 is biased inward toward engagement with shoulder82. In this regard, a collar51 is preferably positioned withinhandle30 for engagingspring50 in the radial direction and permitting mid-section44 of shaft36 to slide therethrough without engaging spring51. When button48 is depressed, ledge49 is pivoted radially outward and out of engagement with shoulder. In alternate embodiments, different button assemblies or triggering mechanisms can be used.
• In a preferred embodiment, a[0024]thumb slide52 is positioned along a portion ofhandle30 opposite activation button48 and is moveable in the longitudinal direction for moving shaft36 from an unloaded to a loaded position.Thumb slide52 partially extends withinchannel40 for engaging shaft36 and moving shaft36 in the longitudinal direction. In an unloaded position, shoulder45 engages an inner ledge53 ofthumb slide52 and whenthumb slide52 is moved in the proximal direction by an operator, shaft36 is also retracted. To move shaft36 to the loaded position,thumb slide52 is moved in the proximal direction until shoulder45 slides beyond ledge49 of button48 and ledge49 engages shoulder45, thereby locking shaft36 in the loaded position. This shaft retraction will also compress firing spring38. In a preferred embodiment, aspring54 is housed withinhandle30 andbiases thumb slide52 in the distal direction and once shaft36 is in the loaded position, the thumb slide is released and returns to its resting position. Once shaft36 is again in the loaded position, another tack can be inserted into theextension32.
• Referring to FIGS.[0025]3-4, once the insertion device is loaded, the insertion device can be used to fasten aplate56 or other device to a bone57. In operation, ahole58 is pre-drilled in the bone tissue at the desired insertion location and theinsertion device10 is placed adjacent the insertion location and the tack is aligned withhole42. The activation button48 is depressed to release shaft36, and shaft36 is driven in the distal direction by the force of firing spring38 thereby drivingtack20 into the bone tissue. As shown in FIG. 4, oncetack20 is inserted into bone,insertion device10 is withdrawn from the insertion location and tack20 is separated fromchannel18. When theinsertion device10 is withdrawn, theforces holding shaft22 oftack20 to bone57 are greater than the forces of the interference fit betweenhead24 andchannel18 so thathead24 oftack20 is separated fromdistal end16, leavingtack20 secured to the bone. Thedevice10 can then be reloaded by moving the thumb slide in the proximal direction as explained above and inserting slightly smaller external dimensions than the internal dimensions ofcover78 so that the proximal end of sleeve82 can be inserted into the distal end ofcover78 and sleeve82 can move in the axial direction with respect to cover78. As best seen in FIG. 9, sleeve82 can include prongs that interlock with ridges on the interior ofcover78 so that when sleeve82 is inserted intocover78, sleeve82 is not inadvertently removed fromcover78 in the distal direction. In a preferred embodiment, sleeve82 has prongs84 that are flexible and are collapsible or bendable into the interior of sleeve82 so that sleeve82 can be removed fromcover78 for cleaning, disassembly, or replacement. Prongs84 are biased radially outwardly so that sleeve82 can be easily reattached by simply pushing the sleeve into the cover in the proximal direction. The distal end of sleeve82 preferably has a pronged tip similar to that described previously for retaining a fixation element.
• A[0026]central channel90 extends withinhandle72 and throughextension74 and houses a firing spring91 and ashaft member92 similar to the embodiment of FIG. 1. Firing spring91 is biased between force adjustment dial93 and the proximal end ofshaft92. Adjustment dial93 includes aknob100 with internal threading that engages an externally threadedadjustment slider102 that is slidably housed withinchannel90. Whenknob100 is rotated,adjustment slider102 slidably moves withinchannel90 and compresses or decompresses spring91 for adjusting the amount of force that is exerted onshaft92 and consequently the tack during insertion. A pair ofknob retaining screws104 extend radially inward from the exterior ofhandle72 and engage a circular groove inknob100 for retainingknob100 in the proximal end ofhandle72. Aguide screw106 extends inward fromhandle72 and engage a longitudinal groove inadjustment slider102 to prevent the slider from rotating.
• [0027]Shaft92 extends longitudinally withinhandle72 and is generally identical to shaft36 described above, moving between a loaded and an unloaded position.Shaft92 includes abase portion94, a mid-section96 having a smaller diameter thanbase portion94, and atip portion98 having a smaller diameter thanmid-section96. A first shoulder95 is positioned at the transition of base portion95 andmid-section96 and a second shoulder97 is positioned at the transition ofmid-section96 andtip portion98.Device70 includes anactivation button108 similar to button48 described above for facilitating movement ofshaft92 from the loaded to the unloaded position in the same fashion as described with respect to the embodiment of FIG. 1. To moveshaft92 from the unloaded to the loaded position, holding sleeve82 andtip portion98 ofshaft92 is retracted in the proximal direction until shoulder97 ofshaft92 slides beyondbutton108 and the button engages shoulder97, thereby lockingshaft92 in the loaded position in a similar fashion to button48 described above. Also,insertion device70 preferably has aspring80 housed withinspring cover78 that biases holding sleeve82 in the distal direction and onceshaft92 is in the loaded position, the holding sleeve is released and returns to its resting position. In this way,shaft92 can be easily moved from the unloaded to the loaded position, by depressingdevice70 in the distal direction against a solid object, such as a table or a surgeons hand. In all other respects, the method of operation or use ofdevice70 is similar to the method described above with respect todevice10.
• Referring to FIGS.[0028]10-11, another embodiment of aninsertion device110 is shown that has yet another alternative loading mechanism. In all other respects,device110 is similar todevice70 described previously.Insertion device110 has acam112 for movingshaft92 from the unloaded to the loaded position. In this embodiment,shaft92 haspins114 extending outwardly therefrom that engage aninternal ramp116 withincam112 and whencam112 is rotatedpins114 slide along ramp1116 in the proximal direction and thereby moveshaft92 in the proximal direction andshaft92 is retracted until shoulder97 ofshaft92 slides beyondbutton108 and the button engages shoulder97, thereby lockingshaft92 in the loaded position in a similar fashion to button48 described above. Aftershaft92 is locked into the loaded position,cam112 is rotated to provide clearance forpins114 to move in the distal direction during the unloading or firing movement ofshaft92.
• While it is apparent that the illustrative embodiments of the invention herein disclosed fulfill the objectives stated above, it will be appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments which come within the spirit and scope of the present invention.[0029]

Claims (10)

What is claimed is:

1. A device for attaching a fixation element to bone, comprising:

a longitudinal member extending along a longitudinal axis from a proximal end to a distal end and having a channel extending therein adapted for receiving at least a portion of one fixation element; and

a shaft positioned coaxially within and extending along at least a portion of the longitudinal member, at least a portion of the shaft retained within the channel of the longitudinal member and having a distal end configured and adapted to contact at least a portion of the fixation element,

a spring positioned adjacent the shaft for resiliently biasing the shaft in an axial direction,

wherein the shaft is moveable with respect to the longitudinal member to drive the fixation element into bone.

2. The device ofclaim 1, further comprising an adjustment gauge for adjusting the bias of the spring.

3. The device ofclaim 1, wherein the shaft is moveable from a loaded position to a unloaded position.

4. The device ofclaim 3, further comprising a locking mechanism for engaging the shaft, wherein the locking mechanism is moveable from a first position to a second position, and when the locking mechanism is in the first position the shaft is locked in the loaded position and when the shaft is in the second position the shaft is moveable to the second unloaded position.

5. The device ofclaim 4, wherein the locking mechanism is pivotally mounted to the longitudinal member and is resiliently biased into the locking position.

6. The device ofclaim 3, further comprising a loading mechanism for engaging the shaft and moving the shaft from the unloaded to the loaded position.

7. The device ofclaim 6, wherein the loading mechanism comprises a slide member moveably mounted to the longitudinal member that is operable by a user to manually move the shaft in an axial direction.

8. The device ofclaim 7, wherein the slide member is resiliently biased out of engagement with the shaft.

9. The device ofclaim 3, wherein the shaft is moveable to the loaded position by applying force on the distal end of the device.

10. The device ofclaim 6, further comprising at least one pin member rigidly mounted tot he shaft and extending radially therefrom, and

wherein the loading mechanism comprises a cam mechanism that has an internal ramp for engaging the pin and moving the shaft in the axial direction.

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