Surgery – Instruments – Suture retaining means
Reexamination Certificate
2000-06-30
2003-11-25
Milano, Michael J. (Department: 3731)
Surgery
Instruments
Suture retaining means
Reexamination Certificate
active
06652560
ABSTRACT:
The present invention relates to a bone anchor, in particular, but not exclusively, to a bone anchor for graft fixation such as tendon or ligament fixation.
BACKGROUND OF THE INVENTION
Due to increasing involvement of people with active sport, injuries are becoming increasingly common where tissues such as ligaments or tendons tear or detach from bone. Surgical techniques have been developed to reconstruct such torn soft tissues and to re-attach them to the relevant bone. One of the most common types of such injuries is tearing of the Anterior Cruciate Ligament (ACL). The Anterior Cruciate Ligament connects the femur to the tibia at the centre of the knee joint. Reconstruction of such tissues generally involves replacement with a graft such as autologous or artificial tendon. An autologous tendon graft may be taken from the patients patellar tendon or, alternatively, the semitendinosus may be utilised. A typical fixation technique involves the use of a circular button fixation device which is located on the outside of the femur above the knee. As this is some distance from the site where the graft will be utilised in the knee joint, sutures are used to attach the graft to the femur button. The main disadvantage of this technique is that incisions need to be made through the skin and quadriceps muscle resulting in trauma to the leg and a cosmetically undesirable procedure. U.S. Pat. No. 5,645,588 describes an improved technique whereby the ligament anchor may be threaded through a femoral tunnel formed through the femur from the centre of the knee but such still involves the use of sutures attached directly to the fixation device on the outside of the femur above the knee and through which the graft is looped before passing out of the femoral tunnel before being secured to the tibia. Using such techniques inevitably involves the introduction of potential sources of loosening of the graft by way of stretching of the suture. This can cause movement in the graft during subsequent patient mobility which hinders the healing and grafting process. Furthermore, the use of sutures involves the tying of knots which themselves result in some subsequent stretch in the suture, increasing the likelihood that the graft will have inappropriate tension for its intended purpose. The suture itself may also fail under the high tensile forces to which it is subjected during use. PCT/US97/22061 attempts to solve this problem by providing an interference fit insertion element with a proximal apperture through which a graft may be threaded or attached. The technique involves securement of the interference end of the device into the central cancellous area of the bone. Unfortunately, this softer area of the bone may not provide sufficient anchoring of the device to resist the tensions to which the graft is subject in use.
U.S. Pat. No. 5037422 also relates to the anchoring of sutures for securement of a suture to a bore hole in a bone. The device is shown secured to the cancellous bone. The device is for use in soft tissue fixation to the outside of the bone and not fixation within the bore hole itself.
Futhermore, it is not suitable for graft fixation and is only applicable to sutures.
A device for graft fixation using sutures is described in EP 0 619 982 where the anchor includes a body and a plurality of barbs located in axially aligned, circumferentially spaced relation to each other about the body. The barbs have a normal configuration wherein they extend rearwardly and radially outwardly from the anchor body to outer ends which are normally located outside a longitudinal projection of the largest geometric cross-section of the body transverse to its longitudinal axis. The device utilises sutures and suffers from the drawbacks previously outlined. It also relies upon interference between the barbs and the soft cancellous bone area.
SUMMARY OF THE INVENTION
According to the present invention there is provided a bone anchor suitable for soft tissue-bone fixation comprising an anchoring member, the anchoring member having a head portion at the distal end thereof and supporting means at the proximal end thereof operable to be urged against the inside surface of the cortical bone, wherein soft tissue locating means are located on the exterior of at least the said head portion.
Advantageously, by having soft tissue locating means on the exterior of the head portion, the soft tissue may be securely located over the exterior of the head to anchor the soft tissue in position. Compression force may then be applied from the trailing ends of the soft tissue urging the support means against the inside surface of the cortical bone through which the hole has been drilled.
A further advantage of the locating means is that it allows the soft tissue to be anchored directly by the anchoring member without the need for interconnecting sutures.
To carry out its function of being urged against the inside surface of the cortical bone in the region around the hole that has been drilled, in use, at least a part of the supporting means is preferably wider or capable of being made wider than the hole that has been drilled.
Preferably, access means are provided in the body of the anchoring member to allow the soft tissue access from the exterior of the member to the hole in the bone.
The access means may be in the form of one or more apertures but, preferably, the supporting means is in the form of a number of legs depending from the head portion and a guide means or spacing between adjacent legs provides access from the exterior of the anchoring member to the hole in the bone.
Preferably, the locating means extends, at least partially, down the outside of the sides of the anchoring member to guide the elongate soft tissue and, preferably, urge it against the walls of the bone hole. Advantageously, this encourages grafting of the soft tissue to the surrounding bone.
Preferably, at least the lowermost portion of the supporting means at the proximal end of the anchoring member extends outwardly to a greater extent than the head portion.
The supporting means may be inwardly radially resiliently deformable at least at the said lowermost portion thereof, so that by compressing the sides of the supporting means radially inwardly, a lowermost portion which is wider than the bone hole may be eased therethrough and, upon release of the compression, the supporting means may then expand inside the hole so that the supporting means may then be urged back against the bone so that the bottom surface at proximal end of the supporting means abuts against the inside surface of the cortical bone in the region around the hole.
The legs may be thickened on the outside thereof at the proximal end to provide the wider lowermost portion of the anchor. Preferably, the anchor member is hollow and the thickness of the bottom surface at the proximal end thereof is such that, in use, the outermost portion of the surface is urged against the inside surface of the cortical bone around the region of the hole whereas the innermost portion of the surface projects over the hole. In this manner, when the proximal end comprises the ends of a number of legs, the gaps between adjacent legs provide access to the hole for tissue guided between adjacent legs. Alternatively, or in addition, the supporting means may be outwardly expandable, preferably, by use of expansion means.
Preferably, the supporting means may be expanded by means of a wedge means or an expansion tool Preferably, the supporting means comprise a number of legs depending from the head portion and the expansion tool or wedge means may be located between the legs to urge the legs radially outwardly with respect to the bone hole. The wedge means may be driven into the anchor means to urge the legs radially outward with respect to the hole. The wedge means may be left in the anchor after use. The wedge means may be in the form of a peg but any suitable shape which could be accommodated by the anchor between the legs may be employed.
Preferably, at least three legs depend from the head portion, more p
Gerke Peter
Hein Dietmar
Reay-Young Clive
Woods Nicholas
ArthroCare Corporation
Batt Richard
Davis D. Jacob
Milano Michael J.
Raffle John T.
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