Note: Descriptions are shown in the official language in which they were submitted.
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FORCEPS
RELATED APPLICATIONS
There is no related application.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
Not applicable.
REFERENCE TO SEOUENCE LISTING, A TABLE OR A COMPUTER
PROGRAM LISTING COMPACT DISC APPENDIX
None.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention is generally directed toward the surgical treatment of
articular
chondral defects and is more specifically directed toward a surgical forceps
for holding a
cylindrical allograft cartilage implant plug having a cartilage face and bone
body to allow
trimming of the same.
2. Description of the Prior Art
Articular cartilage injury and degeneration present medical problems to the
general
population which are constantly addressed by orthopedic surgeons. Every year
in the United
States, over 500,000 arthroplastic or joint repair procedures are performed.
These include
approximately 125,000 total hip and 150,000 total knee arthroplastics and over
41,000 open
arthroscopic procedures to repair cartilaginous defects of the knee.
In the knee joint, the articular cartilage tissue forms a lining which faces
the joint cavity
on one side and is linked to the subchondral bone plate by a narrow layer of
calcified cartilage
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tissue on the other. Articular cartilage (hyaline cartilage) consists
primarily of extracellular
matrix with a sparse population of chondrocytes distributed throughout the
tissue. Articular
cartilage is composed of chondrocytes, type II collagen fibril meshwork,
proteoglycans and
water. Active chondrocytes are unique in that they have a relatively low
turnover rate and are
sparsely distributed within the surrounding matrix. The collagens give the
tissue its form and
tensile strength and the interaction of proteoglycans with water give the
tissue its stiffness to
compression, resilience and durability. The hyaline cartilage provides a low
friction bearing
surface over the bony parts of the joint. If the cartilage lining becomes worn
or damaged
resulting in lesions, joint movement may be painful or severely restricted.
Whereas damaged
bone typically can regenerate successfully, hyaline cartilage regeneration is
quite limited
because of it's limited regenerative and reparative abilities.
Articular cartilage lesions generally do not heal, or heal only partially
under certain
biological conditions due to the lack of nerves, blood vessels and a lymphatic
system. The
limited reparative capabilities of hyaline cartilage usually results in the
generation of repair
tissue that lacks the structure and biomechanical properties of normal
cartilage. Generally, the
healing of the defect results in a fibrocartilaginous repair tissue that lacks
the structure and
biomedical properties of hyaline cartilage and degrades over the course of
time. Articular
cartilage lesions are frequently associated with disability and with symptoms
such as joint pain,
locking phenomena and reduced or disturbed function. These lesions are
difficult to treat
because of the distinctive structure and function of hyaline cartilage. Such
lesions are believed
to progress to severe forms of osteoarthritis. Osteoarthritis is the leading
cause of disability and
impairment in middle-aged and older individuals, entailing significant
economic, social and
psychological costs. Each year, osteoarthritis accounts for as many as 39
million physician
visits and more than 500,000 hospitalizations. By the year 2020, arthritis is
expected to affect
almost 60 million persons in the United States and to limit the activity of
11.6 million persons.
There are many current therapeutic methods being used. None of these therapies
has
resulted in the successful regeneration of hyaline-like tissue that withstands
normal joint
loading and activity over prolonged periods. Currently, the techniques most
widely utilized
clinically for cartilage defects and degeneration are not articular cartilage
substitution
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procedures, but rather lavage, arthroscopic debridement, and repair
stimulation. The direct
transplantation of cells or tissue into a defect and the replacement of the
defect with biologic or
synthetic substitutions presently accounts for only a small percentage of
surgical interventions.
The optimum surgical goal is to replace the defects with cartilage-like
substitutes so as to
provide pain relief, reduce effusions and inflammation, restore function,
reduce disability and
postpone or alleviate the need for prosthetic replacement.
Lavage and arthroscopic debridement involve irrigation of the joint with
solutions of
sodium chloride, Ringer or Ringer and lactate. The temporary pain relief is
believed to result
from removing degenerative cartilage debris, proteolytic enzymes and
inflammatory mediators.
These techniques provide temporary pain relief, but have little or no
potential for further
healing.
Repair stimulation is conducted by means of drilling, abrasion arthroplasty or
microfracture. Penetration into the subchondral bone induces bleeding and
fibrin clot
formation which promotes initial repair, however, the tissue formed is fibrous
in nature and not
durable. Pain relief is temporary as the tissue exhibits degeneration, loss of
resilience, stiffness
and wear characteristics over time.
The periosteum and perichondrium have been shown to contain mesenchymal
progenitor cells capable of differentiation and proliferation. They have been
used as grafts in
both animal and human models to repair articular defects. Few patients over 40
years of age
obtained good clinical results, which most likely reflects the decreasing
population of
osteochondral progenitor cells with increasing age. There have also been
problems with
adhesion and stability of the grafts, which result in their displacement or
loss from the repair
site.
Osteochondral transplantation or mosaicplasty involves excising all injured or
unstable
tissue from the articular defect and creating cylindrical holes in the base of
the defect and
underlying bone. These holes are filled with autologous cylindrical plugs of
healthy cartilage
and bone in a mosaic fashion. The osteochondral plugs are harvested from a
lower weight-
bearing area of lesser importance in the same joint. Reports of results of
osteochondral plug
autografts in a small numbers of patients indicate that they decrease pain and
improve joint
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function, however, long-term results have not been reported. Factors that can
compromise the
results include donor site morbidity, effects ofjoint incongruity on the
opposing surface of the
donor site, damage to the chondrocytes at the articular margins of the donor
and recipient sites
during preparation and implantation, and collapse or settling of the graft
over time. The limited
availability of sites for harvest of osteochondral autografts restricts the
use of this approach to
treatment of relatively small articular defects and the healing of the
chondral portion of the
autograft to the adjacent articular cartilage remains a concern.
Transplantation of large allografts of bone and overlying articular cartilage
is another
treatment option that involves a greater area than is suitable for autologous
cylindrical plugs, as
well as for a non-contained defect. The advantages of osteochondral
allograffts are the potential
to restore the anatomic contour of the j oint, lack of morbidity related to
graft harvesting, greater
availability than autografts and the ability to prepare allografts in any size
to reconstruct large
defects. Clinical experience with fresh and frozen osteochondral allografts
shows that these
grafts can decrease joint pain, and that the osseous portion of an allograft
can heal to the host
bone and the chondral portion can function as an articular surface. Drawbacks
associated with
this methodology in the clinical situation include the scarcity of fresh donor
material and
problems connected with the handling and storage of frozen tissue. Fresh
allografts carry the
risk of immune response or disease transmission. Musculoskeletal Transplant
Foundation
(MTF) has preserved fresh allografts in a media that maintains a cell
viability of 50% for 35
days for use as implants. Frozen allografts lack cell viability and have shown
a decreased
amount of proteoglycan content which contribute to deterioration of the
tissue.
Various studies have also been undertaken by Musculoskeletal Transplant
Foundation
to utilize allograft cylindrical cartilage capped bone plugs for cartilage
defect replacement.
When using allograft plug replacement the cylindrical plug is handled by the
surgeon so that it
can be trimmed to a correct length for the specific application. Consequently
a need for an
improved cylindrical bone plug handling forceps is necessary to allow the
surgeon to easily
handle the cylindrical plug during the plug trimming and implantation process.
A number of
patents have been directed toward clamps or forceps for holding allograft and
autograft
cylindrical plugs so that the same can be trimmed to size to fit into the cut
bore of the excised
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area or to hold the cylindrical plug for insertion into the cut bore.
United States Patent Numbers 6,488,033 and 6,852,114 (a divisional application
of the
'033 patent) issued respectively December 3, 2002 and February 8,2005 are
directed toward an
osteochondral transplant workstation for cutting a core out of an allograft
bone held in an
adjustable vise with a lubricated rotary cutting bit. The core is removed from
the bit, held in a
specially designed set of pliers, and cut to size by a saw blade to fit into a
blind bore which has
been drilled into the patient's arthritic defect area.
Bone clamps or pliers are well known in the medical profession for various
uses. Bone
clamps are reusable devices and therefore longevity is a desirable
characteristic. Generally,
bone clamps are utilized to move broken bones into aligned position or hold
bone fragments
together while surgical procedures (e.g., installation of a screw, plate, pin,
or wire) are
performed. When performing surgery to repair a broken bone, it is important to
clamp the bone
fragments together while a mending device (e.g., a screw, plate, pin, or wire)
is being installed
so that the bone fragments can be maintained in alignment with substantially
no gaps
therebetween. For example, bone clamps may be utilized to hold bone plates in
position across
a bone fracture and/or to align the fractured bones while the bone plate(s)
are affixed thereto or
to place bone plugs in B-T-B surgery.
Typically, bone clamps utilize a ratchet mechanism to control movement of the
bone
clamp and to maintain the bone clamp in locked position once it is operatively
positioned.
Ratchet mechanisms utilized with prior art bone clamps are generally of two
types: (1) a
unidirectional ratchet, e.g., of the type utilized with standard forceps, and
(2) a bidirectional
ratchet having a selectively actuatable lock mechanism to retain the pawl in
locked position
between two consecutive ratchet teeth. United States Patent No. 5,697,933
issued
December 16, 1997 is directed toward a bone-tendon-bone drill guide with a
pair of scissor
arms connected at a pivot with jaws at one end which include curved surfaces
for engaging a
bone end and a straight ratchet brace that is pivotally connected to the lower
end of one
scissoring arm. The j aws are provided with marking indicia. The straight
brace pivots an edge
into alignment with a single tooth that extends from the bottom end of the
other scissoring
arm, the straight brace including a series of teeth formed along its edge to
engage the single
CA 02618908 2008-01-24
tooth and is spring biased to urge the series of teeth against the single
tooth.
United States Patent No. 6,159,217 issued December 12,2000 discloses a
trochlear
clamp having curved jaws with the internal surfaces provided with a plurality
of teeth, one of
the arms being provided with a ratchet assembly to hold the arms and jaws in a
fixed position.
United States Patent No. 5,578,032 issued November 26, 1996 discloses a bone
clamp
with a ratchet mechanism formed on the proximal ends of pivotable scissor arms
and a caliper
type clamp mounted on the distal ends of the scissor arms.
United States Patent No. 6,315,780 issued November 13, 2001 is directed toward
a bone
clamp for dynamic and non dynamic compression of transverse fractures with
toothed jaw
clamps located at the distal ends of pivotable scissor arms and a ratchet
mechanism located at
the proximal ends of the scissor arms.
It is desirable to have a forceps instrument for properly positioning a
cutting guide to
ensure the accuracy in the trimming of an osteochondral bone core.
The present invention was designed to overcome prior art instruments and
provide a
simple to use core preparation devise which accurately fits into the patient's
bore area to form a
uniform cartilage surface for the patient.
SUIVIMARY OF THE INVENTION
A forceps for the preparation of osteochondral allograft cartilage implants
having a
pivotable scissor arms with distal curved jaws to hold implant replacement
cores. The curved
jaws have a plurality of inner teeth to hold the core implant for trimming and
are locked in
position with a spring loaded ratchet mechanism and pawl located on respective
scissor arms.
It is an object of the invention to provide a surgical forceps for forming
osteochondral
allograft plugs with a cartilage layer which can be locked to provide jaw
members which are
fixed in position.
It is also an object of the invention to provide a surgical forceps allowing
easy grasping
of a cartilage repair implant which has a cartilage layer contoured to the
defect site;
It is further an object of the invention to provide a surgical forceps which
can be easily
used by the surgeon to create correctly dimensional and contoured cartilage
implants.
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It is yet another object of the invention to provide a surgical forceps which
can be easily
cleaned and sterilized.
It is still another object of the invention to provide forceps with marking
indicia along
the jaw members so that accurate core lengths for the implant can be obtained.
These and other objects, advantages, and novel features of the present
invention will
become apparent when considered with the teachings contained in the detailed
disclosure along
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of the forceps invention with the clamp jaws in
position;
Figure 2 is a perspective view of the forceps invention of Figure 1 with the
clamp jaws
in a closed position holding a cartilage plug workpiece which is shown in
phantom;
Figure 3 is a top plan view of the forceps of Figure 2;
Figure 4 is a bottom plan view of the forceps of Figure 2;
Figure 5 is a rear elevation view of the forceps shown in Figure 2;
Figure 6 is a partial enlarged side elevation view of the forceps a.rm taken
from the pawl
arm side;
Figure 7 is an enlarged perspective view of the clamp jaws of the forceps;
Figure 8 is an enlarged top plan view of the clamp jaws shown in Figure 7;
Figure 9 is a partial enlarged view of the jaw teeth shown in Circle A of
Figure 8;
Figure 10 is a front elevation view of the clamp jaws shown in Figure 8; and
Figure 11 is a side elevation view of the clamp jaws shown in Figure 8.
DESCRIPTION OF THE INVENTION
The term "tissue" is used in the general sense herein to mean any
transplantable or
implantable tissue such as bone.
The terms "transplant" and "implant" are used interchangably to refer to
tissue
(xenogeneic or allogeneic) which may be introduced into the body of a patient
to replace or
supplement the structure or function of the endogenous tissue.
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The terms "autologous" and "autograft" refer to tissue or cells which
originate with or
are derived from the recipient, whereas the terms "allogeneic" and "allograft"
refer to tissue
which originate with or are derived from a donor of the same species as the
recipient. The terms
"xenogeneic" and "xenograft" refer to tissue which originates with or are
derived from a species
other than that of the recipient.
The present invention is directed towards an implant holding forceps 20
preferably
constructed of 410 or 420 stainless steel. The preferred embodiment and best
mode of the
invention is shown in Figures 1- 11. In the inventive forceps 20, a workpiece
in the form of
an allograft plug or core 200 having a cartilage cap 202 and a bone base 204
which is held in
the forceps 20 for trimming for implantation into a patient.
The forceps 20 has a pair of scissor arms 22 and 24 which are pivotally
connected
together by a pivot, ( not shown) located in a pivot housing 25 as shown in
Figures 1 and 2
which is formed by arm 24. The proximal end of arm 22 is formed with an
inwardly curved
grasping end 26 with the external surface of the curved end 26 being provided
with a tooth or
pawl 28 located at about the mid point of the curved end 26. The distal end of
arm 22 has an
angled neck portion 30 with a curved jaw member 32 extending therefrom. The
angled neck
portion 30 is angled in a range of 9011 to 120 preferably 110 from the plane
of the pivot
housing 25. The curved jaw member 32 which is in the form of a semi-circle has
a plurality of
teeth 33 located around its inner curved surface extending from the distal end
of the jaw up to
the base of notched cutout 36, each tooth preferably forming a 60g angle with
an adjacent tooth.
The distal end 34 of jaw member 32 is preferably planar and is formed with a
notched cutout
36 with the planar surface being provided with laser cut measurement indicia
38 having a.2
line thickness. The spaced measurement indicia 38 are preferably in
millimeters and are
scribed at spaced intervals along the end surface of each jaw as shown in
detail in Figures 7 and
so that the implant core 200 can be trimmed to an exact length for placement
in a bore cut in
the patient when the cartilage defect is removed. The markings 38 determine
locations along
the implant core length for trimming the core to a length which fit into the
patients bore formed
by removing the defect area.
The proximal end of arm 24 is ergonomically curved at 40 and has a pivoting
ratchet
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assembly 50 mounted on the distal end. The ratchet assembly 50 comprises a
yoke 42
extending outward from the inner surface of the arm 24 holding the pivot base
section 53 of a
straight ratchet bar body 52. The pivot base section 53 is stepped from the
ratchet bar body and
has planar side surfaces which are pivotally mounted to the yoke 42 by pin
means not shown. A
plurality of one directional teeth 54 are formed on the inner surface of
ratchet bar body 52 and
the outer surface 55 of the ratchet bar body is smooth and planar. The teeth
54 engage a tooth
or paw128 extending from arm 22 allowing the arms 22 and 24 and their
respective jaws to be
held in a fixed position with respect to each other. The end 57 of pivot
section 53 of the bar
body is engaged by a steel leaf spring 60 having a tip 62 which extends
through yoke 42, the
spring being mounted to arm 24 by a screw or fastener 64 which extends through
a hole in the
spring 60 and through a threaded hole 61 formed in arm 24. Thus the ratchet
bar body 52 is
urged inwardly towards the jaws by spring 60 with arm 22 and paw128 driving
the bar body
52back against the spring bias. The spring biasing is overcome by lifting the
bar body away
from the single tooth 28
The distal end of arm 24 has an angled neck portion 130 and a curved jaw
member 132.
The angled neck portion 130 is angled in a range of 904 to 1209 from the plane
of the top
surface of the jaw member 132. The curved jaw member 132 has a plurality of
teeth 33 around
a portion of its inner curved surface, each tooth preferably forming a 60P
angle with the
adjacent tooth and is positioned identical to that of the opposing jaw 32. The
end 134 of jaw
member 132 is preferably planar and has a notched cutout 136 with the planar
surface being
provided with measurement indicia 138, which is the same as measurement
indicia 38.
The principles, preferred embodiments and modes of operation of the present
invention
have been described in the foregoing specification. However, the invention
shoi9uld not be
construed as limited to the particular embodiment which have been described
above.
Variations and changes may be made by others without departing from the scope
of the present
invention as defined by the following claims:
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