Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
1999-10-22
2001-10-23
Mancene, Gene (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
Reexamination Certificate
active
06306142
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to methods and apparatus for harvesting and implanting bone plugs. The invention has particular utility in repairing damaged bone tissue, such as articular cartilage and underlying subchondral cancellous bone in the knee and other weight-bearing joints.
Weight-bearing joints, such as the knee, are particularly susceptible to injuries caused by friction between opposing bone surfaces. To understand the causes of such injuries, it is first necessary to understand the anatomy of a such a joint. In this regard,
FIG. 1
illustrates knee joint
10
. As shown in
FIG. 1
, knee joint
10
connects femur
12
to tibia
14
and fibula
18
via connective tissue
15
and
17
. Interposed between opposing surfaces of femur
12
and tibia
14
are lateral and medial meniscus cartilages
21
and
23
, respectively. Condyles
22
at distal end
11
of femur
12
are supported by meniscus cartilages
21
and
23
on proximal end
13
of tibia
14
. Normally, distal end
11
of femur
12
, including condyles
22
, is covered by layer
28
of cartilaginous material which is about 5 mm thick. This layer
28
is called the articular cartilage.
Articular cartilage
28
forms a generally resilient pad which is fixed to distal surface
11
of femur
12
in order to protect femur
12
from wear and mechanical shock. When lubricated by fluid in knee joint
10
, articular cartilage
28
provides a surface which is readily slidable on the underlying surfaces of meniscus cartilages
21
and
23
or on proximal surface
13
of tibia
14
if one or both of meniscus cartilages
21
and
23
is partially or totally absent. Problems arise, however, if articular cartilage
28
becomes injured due to excessive wear. For example, articular cartilage
28
can become torn or thin, or holes can develop therein. As a result of such injuries, osteochondritis and/or arthritis can develop, making movement of the joint painful. In extreme cases, these conditions can result in disability if not treated.
Injuries of the foregoing type can be treated by replacing the joint, or portions thereof, with artificial materials. In some cases, however, it is possible to treat the injury by replacing only the bone tissue (i.e., the articular cartilage and/or underlying bone) at the site of the injury with a graft, or plug, from a healthy site. This option is preferable for a number of reasons. For example, surgery to transplant a bone plug is less invasive than that required for a joint replacement. In fact, bone plug transplant surgery is typically performed arthroscopically. Moreover, transplanting bone plugs leads to fewer post-operative complications, a shorter rehabilitation period, and better results overall, since it actually leaves patients with their original joint intact.
Surgical techniques for transplanting bone plugs typically involve removing the damaged bone tissue by drilling or cutting a hole at the site of the damage, and plugging this hole with a bone plug extracted from healthy bone tissue in the patient's body. This healthy tissue is generally extracted from non-load-bearing joints or surfaces in order to minimize patient substantial discomfort.
Surgical instruments are currently available which may be used to harvest or extract a bone plug from a donor site and, then, to implant it into a pre-formed hole at a recipient site. A conventional harvesting instrument typically includes a tube having a cutting edge at the distal end. To extract a plug, the instrument is driven into the bone at the donor site and then removed, taking with it a plug of healthy bone tissue.
The conventional instruments for harvesting bone plugs described above suffer from several drawbacks. For example, it is difficult to regulate the size (i.e., the length) of bone plugs extracted by them. Moreover, the bone plug tissue is sometimes unduly damaged or traumatized by excessive forces exerted during extraction or implantation.
Conventional instruments for implanting bone plugs also suffer from drawbacks. Generally, it is difficult to gauge the exact depth of plug insertion and, thus, to avoid slight protrusions or cavities. This problem is compounded in those instances where the donor and recipient sites do not have matching surface contours.
Thus, there exists a need for a bone plug harvesting apparatus which can be more easily used to remove plugs of bone, and which enables a surgeon to regulate the size of the bone plug being removed. In addition, there exists a need for a bone plug implantation apparatus which permits the plug to be implanted level and in proper alignment with the surrounding bone.
In view of the foregoing, an object of the invention is to provide improved methods and apparatus for harvesting and implanting bone plugs.
Another object is to provide such methods and apparatus as to permit the size of extracted plugs to be better regulated.
Still another object of the invention is to provide such methods and apparatus as to minimize trauma to the transplanted plugs.
Still another object is to provide such methods and apparatus as to facilitate accurate placement of bone plugs during implantation.
Yet still another object is to provide such methods and apparatus as to facilitate implantation in instances where the plugs or recipient sites have uneven contours.
SUMMARY OF THE INVENTION
The present invention addresses the foregoing needs by providing, in one aspect, a bone plug implantation apparatus having a translucent and, preferably, a transparent or clear tip, through which the bone plug can be viewed during implantation. Unlike the prior art, inclusion of such a tip permits the surgeon to view the bone plug during implantation, thereby facilitating better placement, alignment and insertion of the plug into the donor site.
According to further aspects of the invention, the apparatus includes a “harvesting” tube which can be used to harvest the plug and which is used to hold the bone plug prior to implanting. The apparatus can also include a push rod that forces the bone plug into a pre-formed hole at the transplant site. The harvesting tube can include an aperture or recessed inner wall that reduces friction on the plug during implantation (and harvesting) and that, thereby, reduces undesirable compression of the plug.
According to further aspects of the invention, the tip has an inner diameter substantially equal to that of the hole into which the bone plug is transplanted. An outer diameter of the tip, however, can be greater than that of the hole. This larger outer diameter forms a shoulder upon which the tip can rest during implantation. The tip also covers the distal end of the harvesting tube and, hence, minimizes the damage that it might otherwise cause at the transplant site.
In still further aspects of the invention, the tip is rotatable relative to the harvesting tube. This facilitates rotation of the bone plug relative to the transplant site, e.g., so that their respective surfaces can be aligned and otherwise better fitted.
According to still another aspect, the present invention provides an apparatus for harvesting plugs from bone tissue. The apparatus includes a harvesting tube, as described above, to which a cutting sheath is fitted. The sheath, which includes a cutting edge and a cutting tooth, can include markings on its outer surface so that the depth of insertion—and, therefore, the length of the bone plug—can be determined during harvesting. The harvesting tube can likewise include markings on its outer surface, e.g., adjacent the aforementioned window, so that the position and length of the plug can be more accurately determined after harvesting.
According to still another aspect, the present invention provides a method of transplanting a bone plug from a donor site to a recipient site. The method includes harvesting the bone plug from the donor site utilizing a bone plug harvesting apparatus as described above. The harvesting tube of the harvesting apparatus is fitted with a tip as described above to form a bone plug implantation
Barnes Bill
Johanson Mark A.
Rose Donald J.
Choate Hall & Stewart
Johnson & Johnson
Mancene Gene
Robert Eduardo C.
Rosen Valarie B.
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