Bone fastener

Details Bone fastener Bone fastener

1999-06-14

2003-02-25

Woo, Julian W. (Department: 3731)

Surgery

Instruments

Orthopedic instrumentation

C606S075000, C411S045000

Reexamination Certificate

active

06524316

ABSTRACT:

BACKGROUND OF THE INVENTION
A variety of techniques are available for affixing objects such as soft tissue to bone. The oldest technique utilizes thread passed through the bone and the tissue to sew the tissue down to the bone. Many sizes, shapes and types of suture and suture needles are available to accomplish this task. Today, this method is still used for repair of tendons and ligaments in older osteoarthritic patients, although passing a suture through bone is generally difficult and tedious.
Soft tissue repairs also have been accomplished with metal screws or staples that attach soft tissue to bone. Metal screws and/or staples are, however, subject to corrosion and consequent loss of structure. Moreover, the presence of metal in an anatomical site can interfere with imaging and diagnostic or therapeutic treatments near the site. For example, any metal implants may have to be removed by surgery prior to magnetic resonance imaging. Patient sensitivity to nickel ions and stainless steel implants has fueled a growing controversy regarding the use of materials containing high quantities of nickel including nickel-titanium alloys such as Nitinol. Also, it is almost impossible to adjust the compression exerted by screws and staples on soft tissue. Thus, these devices are not fully satisfactory for soft tissue repair.
Other devices employ a suture anchor installation affixed to an arc of wire or a plurality of barbs disposed on an outer surface of the suture anchor body. The barbs or arc of wire are set by applying traction to the suture. Unfortunately, it is not always possible to position the anchor at a precise location within a bone if an anchor is being drawn upwards in a bone hole by applying tension to a suture. Furthermore, many of the fastening devices require some type of impact or impulse to set the fastener in position. Impact emplacement or setting of bone/suture anchors may result in injury to the patient as well as placing unnecessary strain on the bone/suture fastener itself.
SUMMARY OF THE INVENTION
The present invention is directed to a novel apparatus for emplacing a bone fastener that eliminates the problems created by conventional bone fastener emplacement devices.
In general, the invention features a bone fastener including an expandable member having an axial channel and an elongated element inserted into the axial channel. The expandable member is configured to be insertible into a bore drilled in bone. The member is expanded using a continuous, compressive force (i.e., pressure without impulse or impact). The expandable member is grasped at its distal end throughout the emplacement procedure and is axially released from an emplacement tool.
In one embodiment, a fastener for coupling an object to a bone is described. The fastener includes a cylindrical expandable member for insertion into an opening in a bone, the member including an outer surface for expandable engagement with an inner surface of the bone opening. An axial channel is defined in the expandable member, the channel extending at least partially between proximal and distal ends of said expandable member. An elongated, insertion element that is compressed into the expandable member is also part of the fastener. The insertion element has proximal and distal ends and a channel defined between the ends for engagement with a suture. Preferably, the insertion element includes a projection that expands the axial channel of the expandable member in an irreversible manner to obtain a press-fit with the bone opening. In preferred embodiments, the outer surface of the expandable member includes a plurality of projections for engagement with the inner surface of the bone opening. The distal end of the expandable member also may include a structure for axially releasing the expandable member from an emplacement device that places the expandable member into a bone opening. In one embodiment, the structure for axially releasing includes a frangible membrane capable of being severed from the expandable member during emplacement of the expandable member in a bone opening.
The invention also pertains to a rivet for coupling an object to bone for use with an expandable member capable of insertion into an opening in a bone. The rivet includes an elongated insertion element adapted for compression into a distal end of the expandable member. The insertion element has a shaft with proximal and distal ends, an outer surface of said shaft including a radially outward projecting portion adapted to expand the expandable member. The distal end of the elongated insertion element includes a radially projecting portion adapted for engagement with a washer that contacts the object to be coupled. The washer, having upper and lower surfaces and a bore defined between the surfaces, is disposed around the shaft of the insertin element. The element is adapted for movement independent of the washer since the radial projection of the insertion element has a different radius of curvature than the washer.
The invention further includes the combination of a bone; an opening defined in the bone and an expandable member inserted into the opening in the bone. The expandable member includes an elongated, insertible element, as described above, and further includes at its distal end, at least part of a means for axially releasing the expandable member from a holder, the holder for emplacing the expandable member in the bone opening.
In preferred embodiments, the expandable member and insertible element are formed out of a bioabsorbable polymer such as polylactide, polyglycolide and combinations thereof.
The invention also pertains to an apparatus for use within an endoscope. The apparatus includes an elongated, substantially hollow holding means for emplacing a bone fastener in a bone opening, the holding means having distal and proximal ends. An expandable member having a proximal end and a distal end integral with the proximal end of the holding means is also included. In one embodiment, the expandable member includes a structure for axially releasing the expandable member from the holding means. The structure may be a frangible membrane disposed intermediate the proximal end of the holding means and the distal end of the expandable member.
A method of attaching soft tissue to bone is also described. The method includes providing an expandable member for insertion into an opening in a bone. The member has defined in it an axial channel having a certain diameter. The member also includes a structure for axially releasing the expandable member from a holding means. Next, the expandable member is engaged at a distal end thereof by way of the emplacement means. The expandable member is inserted into soft tissue and bone while maintaining engagement with the distal end of the expandable member. A continuous, compressive force is then applied to the expandable member to expand the diameter of the axial channel so that an outer surface of the expandable member engages with the bone. The structure for axially releasing the expandable member is then activated, so that the expandable member is released from the emplacement means when the continuous force stops.
An apparatus for placing a bone fastener in an opening in a bone includes the combination of an expandable member with an axial channel defined therein; an elongated, substantially hollow holder for the expandable member, an insertion element for engagement with an inner surface of the axial channel; a structure for axially releasing the expandable member from the holder when the expandable element is fully expanded within the bone opening; a structure adapted for co-axial movement relative to the holder for placing the element into the axial channel of the expandable member; and a structure co-axially moveable within the hollow body for releasing the expandable member from the holder.
The invention also includes a surgical fastener kit. The kit includes an expandable member for insertion into an opening of the bone, the member having an axial channel defined in it and an outer surface fo

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