U.S. patent application number 16/409808 was filed with the patent office on 2019-11-14 for cutting apparatus for bioprocessing bone.
The applicant listed for this patent is Ossium Health, Inc.. Invention is credited to Joseph Ingalls, Brian Johnstone, Erik J. Woods.
Application Number | 20190343112 16/409808 |
Document ID | / |
Family ID | 68465162 |
Filed Date | 2019-11-14 |
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United States Patent
Application |
20190343112 |
Kind Code |
A1 |
Woods; Erik J. ; et
al. |
November 14, 2019 |
Cutting Apparatus for Bioprocessing Bone
Abstract
A bone cutting assembly includes a manually actuated upper
cutting element that carries a plurality of cutting blades
configured to cut through frozen bone segments. A lower cutting
element supports a bone segment to be cut and can include cutting
blades aligned with the cutting blades of the upper cutting
assembly. A pivoting linkage or a rack and pinion arrangement can
be provided between the upper cutting element and a manually
operated handle to provide sufficient mechanical advantage or
leverage to allow an operator to manually cut through the bone.
Inventors: |
Woods; Erik J.; (Carmel,
IN) ; Johnstone; Brian; (Fishers, IN) ;
Ingalls; Joseph; (Westfield, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ossium Health, Inc. |
San Francisco |
CA |
US |
|
|
Family ID: |
68465162 |
Appl. No.: |
16/409808 |
Filed: |
May 11, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62670283 |
May 11, 2018 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C12N 5/0669 20130101;
A61F 2/4644 20130101; C12N 2509/10 20130101; A01N 1/0236
20130101 |
International
Class: |
A01N 1/02 20060101
A01N001/02; C12N 5/077 20060101 C12N005/077 |
Claims
1. A bone cutting apparatus comprising: a lower cutting element
configured to support a bone segment to be cut; an upper cutting
element including a plurality of upper cutting blades facing said
lower cutting element; a frame supporting said upper cutting
element above said lower cutting element for movement toward and
away from said lower cutting element; a manually operable handle;
and a force transmission mechanism connecting said handle to said
upper cutting element to move said upper cutting element toward
said lower cutting element with sufficient force to cut through the
bone segment supported on said lower cutting element.
2. The bone cutting apparatus of claim 1, wherein said lower
cutting element includes a plurality of lower cutting blades facing
said upper cutting element and corresponding to said plurality of
upper cutting blades.
3. The bone cutting apparatus of claim 1, wherein said plurality of
upper cutting blades are arranged in a radial pattern.
4. The bone cutting apparatus of claim 3, wherein the plurality of
upper cutting blades are separated from each other by a uniform
angle in said radial pattern.
5. The bone cutting apparatus of claim 4, wherein the plurality of
upper cutting blades includes four cutting blades separated by 90
degrees.
6. The bone cutting apparatus of claim 4, wherein the plurality of
upper cutting blades includes six cutting blades separated by 60
degrees.
7. The bone cutting apparatus of claim 4, wherein the plurality of
upper cutting blades includes eight cutting blades separated by 45
degrees.
8. The bone cutting apparatus of claim 1, wherein said plurality of
upper cutting blades define a cutting edge configured to cut
through the bone segment, the cutting edge of at least a number of
said plurality of upper cutting blades being perpendicular to the
direction of movement of said upper cutting element.
9. The bone cutting apparatus of claim 1, wherein said plurality of
upper cutting blades define a cutting edge configured to cut
through the bone segment, the cutting edge of at least a number of
said plurality of upper cutting blades being at a non-perpendicular
angle relative to the direction of movement of said upper cutting
element
10. The bone cutting apparatus of claim 1, wherein said lower
cutting element includes a plurality of slots corresponding to said
plurality of upper cutting blades, each of said slots configured to
receive a portion of a corresponding one of said upper cutting
blades when said upper cutting element is moved toward said lower
cutting element.
11. The bone cutting apparatus of claim 1, further comprising a
shroud configured to encircle the upper cutting element and the
bone segment to be cut when the upper cutting element is moved
toward the lower cutting element.
12. The bone cutting apparatus of claim 1, wherein: said frame
includes; a base supporting said lower cutting element; a plurality
of vertical columns supported on said base; a top plate supported
at the top of said plurality of columns; and an intermediate plate
supported by said plurality of columns between said base and said
top plate; and said force transmission mechanism includes: a plate
connected to the manually operated handle, the plate pivotably
mounted at one end of said plate to said top plate to pivot
downward toward said lower cutting element; a linkage pivotably
mounted at one end of the linkage to an end of said plate opposite
said one end; and a shaft pivotably connected at an upper end
thereof to an end of said linkage opposite said one end, and
connected at a lower end thereof to said upper cutting element,
said shaft slidably supported between said upper end and said lower
end by said intermediate plate.
13. The bone cutting apparatus of claim 1, wherein: said frame
includes; a base plate supporting said lower cutting element; a
vertical post supported at a lower end of the post on said base
plate; a mounting element supported at an upper end of said
vertical post; and said force transmission includes; a gear rack
slidably supported by said mounting element for vertical movement
toward and away from said lower cutting element, said gear rack
carrying said upper cutting element; a pinion gear rotatably
supported within said mounting element in meshed engagement with
said gear rack; and pinion shaft carrying said pinion gear and
connected to said manually operable handle, said handle configured
to rotate said pinion shaft with said pinion gear on downward
movement of said handle, whereby rotation of said pinion gear
drives said gear rack and said upper cutting element downward.
14. The bone cutting apparatus of claim 13, wherein said upper
cutting element includes: an upper mounting plate connected to said
pinion shaft; an upper cutter base removably mountable to said
upper mounting plate facing said lower cutting element; and a
number of cutting blades carried by said upper cutter base facing
said lower cutting element.
15. The bone cutting apparatus of claim 14, wherein said frame
includes at least two guide posts and said upper mounting plate is
slidably guided by said at least two guide posts for vertical
movement toward and away from said lower cutting element.
16. The bone cutting apparatus of claim 14, wherein said number of
cutting blades includes replaceable cutting blades that are
removably mounted to said upper cutter base.
17. The bone cutting apparatus of claim 16, wherein said
replaceable cutting blades and said upper cutter base include a
T-slot and mating rib.
18. The bone cutting apparatus of claim 1, wherein said lower
cutting element includes a lower base defining a collection cavity
and a cutting tray above said collection cavity configured to
support the bone segment, said cutting tray configured for bone
fragments to pass into said collection cavity.
19. The bone cutting apparatus of claim 18, further comprising a
collection container removably disposed within said collection
cavity beneath said cutting tray.
Description
PRIORITY CLAIM
[0001] This application is a utility filing from and claims
priority to co-pending application No. 62/670,283, filed on May 11,
2018, the entire disclosure of which is incorporated herein by
reference.
BACKGROUND
[0002] The present disclosure concerns an apparatus useful for
recovering live bone marrow.
[0003] Bone marrow for clinical purposes is harvested from HLA
matched siblings or optimally matched unrelated donors (MUD). Other
graft sources are mismatched haploidentical related or unrelated
donors and umbilical cord blood (CB). When transplanted into
patients with certain diseases, the hematopoietic stern cells
(HSCs) in the donor bone marrow engraft in the patient and
reconstitute immune and hematopoietic systems.
[0004] Bone marrow is also a source for mesenchymal stromal/stem
cells (MSCs) which are self-renewing, multipotent progenitor cells
with multilineage potential to differentiate into cell types of
mesodermal origin, such as adipocytes, osteocytes, and
chondrocytes. In addition, MSCs can migrate to sites of
inflammation and exert potent immunosuppressive and
anti-inflammatory effects through interactions between lymphocytes
associated with both the innate and adaptive immune system.
[0005] Currently bone marrow is typically collected through a hole
created in the outer bone with a trocar needle. A bone marrow
aspiration needle is then introduced into the hole and a syringe is
used to draw the marrow out of the bone. The syringes are then
removed from the sterile field and connected to a collection bag
containing anticoagulants. The marrow is pushed into the bag. This
step is repeated many times, typically in both pelvic bones, and
can often result in contamination of the aspirate.
[0006] Once recovered, bone marrow can be cryopreserved and banked
for future use. This is typically done using a cryoprotectant agent
(CPA) such as dimethyl sulfoxide (DMSO) with or without a
carbohydrate, such as hydroxyethyl starch (HES), in a balanced
electrolyte solution with or without a protein supplement, such as
human or animal serum, platelet lysate, or albumin and with or
without added growth factors. Cells are cooled slowly (-1.degree.
C. to -5.degree. C./min) down to an intermediate, low sub-zero
temperature and then transferred to final storage in vapor or
liquid nitrogen.
[0007] Optimal cryopreservation techniques for bone marrow should
be effective when applied to the whole tissue, with the idea that
stem cells would be isolated following thawing, assuming adequate
permeation of the cells to the CPA. Immediate cryopreservation of
tissues is more practical than direct primary isolation of stem
cells, which requires further processing and expense.
[0008] It is often optimal to cryopreserved whole bone to be
subsequently processed for extraction of the bone marrow. To
adequately cryopreserve bone for subsequent post thaw processing,
the bone must be cooled very slowly (with cryoprotective agents)
e.g. with cooling rates of -0.1.degree. to -4.0.degree. C. per min.
However, to successfully recover live cells rapid warming is
required (e.g. >50.degree. C./min). While cooling rates can
readily be applied in a slow manner, warming large volumes of bone
quickly is problematic. Consequently, there is a need for an
apparatus that can reduce the whole cryopreserved bone to smaller
pieces that can then be placed into a warming medium immediately to
allow rapid thaw.
SUMMARY OF THE DISCLOSURE
[0009] To enable cryopreservation of whole bone and facilitate
subsequent processing of the bone, an apparatus is provided which
can be used to process the bone and recover bone marrow to a
cellular suspension prior to cryopreservation, or to enable the
cryopreservation of whole bone to be subsequently processed. The
apparatus allows either a fresh bone or a cryopreserved bone to be
cut into pieces appropriately sized for further fresh processing or
rapid thawing. In one embodiment, the apparatus is manually
operated with a linkage arrangement or a lever arm and rack and
pinion arrangement providing a mechanical advantage or leverage
sufficient to cut through bone with only manual effort.
[0010] The present disclosure provides a bone cutting apparatus
that comprises a lower cutting element configured to support a bone
segment to be cut and an upper cutting element including a
plurality of cutting blades facing the lower cutting element. A
frame supports the upper cutting element above the lower cutting
element for movement toward and away from the lower cutting
element. The apparatus is provided with a manually operable handle
and a force transmission mechanism connecting the handle to the
upper cutting element to move the upper cutting element toward the
lower cutting element with sufficient force to cut through the bone
segment supported on the lower cutting element.
[0011] In one embodiment, the bone cutting apparatus includes upper
and lower cutting elements, each with aligned cutting blades, in
which the upper cutting element is pushed toward the stationary
lower cutting element to cut through a bone segment positioned
between the two elements. The upper cutting element is carried by a
shaft that is connected to a linkage, that is in turn connected to
a handle. The handle is pivotably mounted to the cutting apparatus
so that pushing the handle downward pushes the upper cutting
element downward with a mechanical advantage derived by the
configuration of the handle and linkage.
[0012] In another embodiment, the upper cutting element is pushed
by a handle applying force through a rack and pinion arrangement. A
ratchet and pawl arrangement control the direction of movement of
the rack that carries the upper cutting element. In this
embodiment, the upper cutting element includes replaceable blades
and a stationary lower cutting tray that supports the bone segment
to be cut. A collection container is disposed beneath the lower
cutting tray to receive the bone fragments at the completion of the
cutting operation.
DESCRIPTION OF THE FIGURES
[0013] FIG. 1 is a perspective view of a bone cutting apparatus
according to one embodiment of the present disclosure.
[0014] FIG. 2 is a perspective view of the apparatus of FIG. 1
shown in one stage of operation.
[0015] FIG. 3 is a perspective view of the apparatus of FIG. 1
shown in another stage of operation.
[0016] FIG. 4 is a perspective view of the apparatus of FIG. 1
shown in a further stage of operation.
[0017] FIG. 5 is an enlarged view of the apparatus shown in FIG.
4.
[0018] FIGS. 6A, 6B are side and top views of cutting elements for
use in the apparatus of FIG. 1.
[0019] FIGS. 7A, 7B are side and top view of alternative cutting
elements for use in the apparatus of FIG. 1.
[0020] FIGS. 8A, 8B are side and top view of further alternative
cutting elements for use in the apparatus of FIG. 1.
[0021] FIGS. 9A, 9B, 9C and 9D are side, top and perspective views
of another alternative cutting elements for use in the apparatus of
FIG. 1, with FIG. 9C showing the cutting elements in different
stages of operation.
[0022] FIG. 10 is a perspective view of a bone cutting apparatus
according to another embodiment of the disclosure.
[0023] FIG. 11 is a side partial cross-sectional view of the
apparatus shown in FIG. 10.
[0024] FIG. 12 is an enlarged cross-sectional view of a portion of
the apparatus shown in FIG. 10.
[0025] FIG. 13 is a top view of the apparatus shown in FIG. 10.
[0026] FIG. 14 is a side view of the apparatus shown in FIG.
10.
[0027] FIG. 15 is an enlarged view of a portion of the apparatus
shown in FIG. 10.
[0028] FIG. 16 is an end view of the apparatus shown in FIG.
10.
[0029] FIG. 17 is an enlarged perspective view of a component of
the apparatus shown in FIG. 10.
[0030] FIG. 18 is an enlarged side perspective view of an upper
cutting element for use in the apparatus of FIG. 10.
[0031] FIG. 19 is a bottom perspective view of the upper cutting
element shown in FIG. 18.
[0032] FIG. 20 is an enlarged perspective view of a cutting blade
for use in the upper cutting element shown in FIGS. 18-19.
[0033] FIG. 21 is a perspective view of a bottom cutting tray for
use in the apparatus shown in FIG. 10
[0034] FIG. 22 is a top view of the bottom cutting tray shown in
FIG. 21.
[0035] FIG. 23 is an enlarged perspective view of a base component
of the apparatus shown in FIG. 10.
[0036] FIG. 24 is an enlarged perspective view of a collection
container for use with the apparatus shown in FIG. 10.
[0037] FIG. 25 is an enlarged perspective view of a blade assembly
assist component for use with the apparatus shown in FIG. 10 and
the upper cutting element and cutting blade shown in FIG.
18-20.
[0038] FIG. 26 is an enlarged end view of a portion of the
apparatus of FIG. 10 shown with a blade assembly assist
component.
DETAILED DESCRIPTION
[0039] For the purposes of promoting an understanding of the
principles of the disclosure, reference will now be made to the
embodiments illustrated in the drawings and described in the
following written specification. It is understood that no
limitation to the scope of the disclosure is thereby intended. It
is further understood that the present disclosure includes any
alterations and modifications to the illustrated embodiments and
includes further applications of the principles disclosed herein as
would normally occur to one skilled in the art to which this
disclosure pertains
[0040] An apparatus 10 is provided, as shown in FIG. 1, for cutting
a bone segment recovered from organ and tissue donors for
subsequent processing. The apparatus includes a frame formed by a
base plate 11 supporting four vertical columns 12. The frame also
includes a top plate 14 is mounted on the four vertical columns and
an intermediate plate 16 is mounted to the columns at a position
between the base plate and top plate. A bone cutting assembly 20 is
provided between the base plate 11 and the intermediate plate 16.
The assembly 20 includes a lower cutter element 22 mounted on the
base plate 11. The lower cutter element is surrounded by a shroud
23 arranged to contain fragments of a whole bone segment B (FIG. 2)
generated in a cutting process. The assembly further includes a
movable upper cutting element 30 that is also surrounded by a
shroud 32. The two shrouds 23, 32 combine to form a chamber C to
contain the whole bone segment during the cutting process, as shown
in FIG. 3. In particular, the upper shroud 32 can be configured to
slide downward toward the lower shroud 23 with the respective edges
24, 33 contacting each other, thereby closing the chamber C with
the bone segment B inside. The edges 24, 33 can have complementary
configurations so that one edge nests within the other edge to
ensure proper alignment of the two shrouds.
[0041] The upper shroud 32 can include a plurality of vertical
slots 34 that can receive a projection 41a on each of the cutting
blades 41 of the upper cutting element 30. The projections 41a on
the blades can thus guide the upper shroud 32 as it is moved from
its uppermost position shown in FIG. 2 to its closed position shown
in FIG. 3. In the closed position, the vertical slots 34 can then
serve as a guide for the cutting blades 41 as the upper cutting
element is moved from its uppermost position shown in FIG. 3 to its
cutting position shown in FIG. 4. In one feature, the two shrouds
are preferably formed of a transparent material, such as glass or
certain plastics, to enable viewing of the whole bone segment prior
to cutting and of the bone fragments after the cutting process.
[0042] The upper cutting element 30 is carried by a shaft 35 that
extends through and is guided by a bore 36 in the intermediate
plate 16. The upper end of the shaft 35 is pivotably connected to a
linkage 40 that is pivotably connected to a handle 42. The handle
42 includes a hand grip portion 42a that is mounted or affixed at a
generally perpendicular angle to a plate 42b, as best seen in FIG.
4. The plate 42b is pivotably mounted to the top plate 14 of the
apparatus. The handle 42 is configured to be manually grasped and
pivoted downward, which in turn pivots the linkage 40 about the end
of the shaft in a direction opposite to the pivot direction of the
handle, to thereby move the shaft 35, and thus the upper cutter
element 30, downward toward the lower cutter element 22. The offset
of the pivot connection of the linkage 40 to the handle 42 relative
to the pivot connection of the handle 42 to the plate 16 provides a
mechanical advantage that enables cutting through the bone segment
B using only manual force. As shown in FIG. 2, the bone segment B
is placed on top of the lower cutter element within the chamber C
defined by the two shrouds 23, 32. The upper cutter element 30 is
pressed into the bone segment to cut the segment into the shapes
and dimensions set by the blades 40, 41 of the two cutter elements
22, 30, as depicted in FIG. 4.
[0043] The upper cutting element 30 can include a piston body 44
(FIG. 3) to which the cutting blades 41 are mounted. The cutting
blades 41 can be separate blades mounted to the piston body or can
be part of a cutting blade component. The piston body 44 can be
engaged to the lower end of the shaft 35 in a conventional manner,
such as by a threaded engagement. A bushing 46 (FIG. 4) can be
affixed or mounted to the underside of the intermediate plate 16 to
provide a bearing or sliding interface for the shaft 35. The shaft
35 may be provided with vertical splines 35a along the length of
the shaft that engage mating vertical grooves (not shown) within
the inner circumference of the bushing 46 to prevent rotation of
the piston body 44 and cutting blades 41 during a cutting
operation.
[0044] The lower cutter element 22 can include a base 47 onto which
the cutting blades 40 are mounted or affixed. As with the cutting
blades 41, the cutting blades 40 can be individually mounted to the
base 47 or can be part of a cutting blade component. The base 47 is
configured to be seated within a cavity or recess 48 defined in the
bottom plate 11, as shown in FIG. 1. In this way, the lower cutting
element 22 can be interchangeable or replaceable. The base 47 and
recess 48 can include an alignment feature, such as a notch and
complementary projection (not shown) to ensure a particular
orientation of the cutting blades 40, and in particular to ensure
that the cutting blades 40 are aligned with their counterpart
cutting blades 41 in the upper cutting element 30. The splines 35a
of the shaft 35 can include one spline that is larger than the
others to mate with a correspondingly deeper groove in the bushing
to align the upper cutter element 30. The key in the alignment
features is that the cutting edges of the upper blades 41 are in
direct alignment with the cutting edges of the lower blades 40 to
properly cut through the bone segment B as the upper cutter element
30 is pushed toward the lower cutter element 22.
[0045] Several different configurations of cutting blades 40, 41
may be incorporated into the respective lower and upper cutter
elements 22, 30. In one embodiment, four blades defining a "+"
configuration can be provided as shown in FIGS. 6A, 6B. The cutting
edges of the lower and upper cutting blades can have the
configuration of the cutting edge 40a shown in FIG. 6A in which the
blade is angled on both sides of the blade to a sharp edge and in
which the edge 40a is linear and generally perpendicular to the
vertical cutting direction. FIGS. 7a, 7b show an embodiment with
six cutting blades having the same cutting edge configuration as
the cutting edge 40a in FIG. 6A. FIGS. 8a, 8b show an embodiment
with eight cutting blades having the same cutting edge
configuration as the cutting edge 40a in FIG. 6A.
[0046] In an alternative embodiment shown in FIGS. 9A-9E, the lower
cutting element 22' only includes the base 47' and does not include
the cutting blades 40 of the previous embodiments. In this
alternative embodiment, the upper cutting element 30' includes
cutting blades 41' that have an angled cutting edge 41a'. The
angled cutting edges 41a' of all of the cutting blades 41' converge
at a central point 41b' that can facilitate the initial entry of
the upper cutter element 30' into the bone segment, as depicted in
FIG. 9C. In order to ensure a solid cut completely through the bone
segment B, the base 47' of the lower cutter element 22' includes a
plurality of slots 47a' that correspond with and are aligned with
the cutting blades 41' of the upper cutter element 30. When the
upper cutter element has been pushed through the bone segment B,
the blades 41' penetrate the slots 47a' so that the entire angled
edge 41a' (FIG. 9A) of the blades are within the slots, as in
"Position 3" in FIG. 9C.
[0047] In specific embodiments, the upper and lower cutter elements
can have a combined cutting height of about 2.5-3.0 inches in order
to cut through bone segments B of the same height. The cutting
blades can have a thickness of about 0.12 inches, tapering to a
sharp point. In the embodiment of FIGS. 9A-9E, the angled cutting
edges can be angled at about 15.degree. relative to the
horizontal.
[0048] A bone cutting apparatus 50 according to another embodiment
of the disclosure is shown in FIGS. 10-26. As shown in FIG. 10, the
apparatus 50 includes a mounting plate 52 with handles 53 that
allow the apparatus to be carried to different locations in a
sterile bone processing facility. A base 55 is mounted to the
mounting plate 52 by thumb screws 56 to permit ready disassembly
and assembly of the apparatus. A post 57 is mounted to the base 55
to extend vertically above the plate 52. The post 57 defines a
shoulder 58 (FIG. 11) on which is mounted a pinion mount 60. The
pinion mount 60 supports a rack 62 for vertical movement relative
to the plate 52. As shown in FIG. 11, the rack 62 engages a pinion
gear 64 that is formed on a pinion shaft 65 (FIG. 17) so that
rotation of the pinion gear 64 produces vertical movement of the
rack 62. A rack spring 75 and a rack bearing 76 provide a lateral
force to hold the rack 62 in toothed engagement with the pinion
gear 64.
[0049] The pinion shaft 65 includes a ratchet gear 70 that is
engaged by a pawl 71, as shown in FIGS. 12, 13, 15. A torsion
spring 72 biases the claw 71a of the pawl 71 into engagement with
the ratchet gear to hold the ratchet gear 70 and thus the pinion
shaft 65 against rotation in one direction, while permitting
rotation in the opposite direction. Thus, as viewed in FIG. 11, the
ratchet gear and pawl are configured to permit rotation of the
shaft 65 and the pinon gear 64 in the clockwise direction to drive
the rack 62 downward. The claw 71a of the pawl prevents
counter-clockwise rotation of the pinion gear, which thereby
prevents upward vertical movement of the rack 62. Counter-clockwise
rotation of the pinion gear 64, and thus upward movement of the
rack 62, can be permitted by depressing the pawl 71 against the
torsion spring 72 to release the claw from the ratchet gear 70. The
thumbwheel knob 77 (FIGS. 12, 16) is mounted to the end of the
pinion shaft 65 and can be manually rotated to rotate the pinion
gear 64 in the counter-clockwise direction to raise the rack
62.
[0050] The ratchet gear 70, and thus the pinion shaft 65, are
manually rotated in the clockwise direction (as shown in FIG. 11)
by way of a handle 74 fastened to a handle mount 73, as shown in
FIGS. 11-16. The handle mount 73 is pivotably supported on the
pinion shaft 65, as best seen in FIG. 12, and the pawl 71 is fixed
to the handle mount 73 so that the pawl can be rotated relative to
the pinion shaft. However, when the claw 71a of the pawl is engaged
to the ratchet gear 70, this rotation of the handle mount causes
rotation of the ratchet gear 70 and thus rotation of the pinion
shaft and pinion gear 64. In particular pushing the handle 74
downward toward the mounting plate 52 produces the clockwise
rotation of the pinion gear 64, leading to the downward movement of
the rack 62. In one specific embodiment, the handle 74 has a
fulcrum length of 18-20 inches, which provides a leverage ratio of
at least 27:1 between the force applied to push the handle down and
the downward force applied by the vertical movement of the rack 62
when cutting through bone, as described in more detail herein. The
pinion gear 64 can have an outer diameter of 1.375 inches with
twelve gear teeth, while the rack can include 20 gear teeth
configured to match the profile of the pinion gear teeth. The rack
teeth thus span a length of 6.219 inches in the specific embodiment
to thereby provide a rack travel distance of about six inches.
[0051] In accordance with this embodiment, the bone cutting
assembly 50 is provided with an upper cutting assembly 80 and a
lower cutting assembly 82 (FIGS. 10-11). The upper cutting assembly
is configured to be moved toward the lower cutting assembly to cut
a bone segment B positioned between the two assemblies, as shown in
FIG. 10. The upper cutting assembly 80 includes an upper blade
mounting plate 84 that is slidably mounted on two guide posts 86
that are themselves supported on the base 55. The plate 84 can
include a pair of bushings 85 to slidably receive the posts, as
best seen in FIG. 11. Each post includes concentrically mounted
springs 87 disposed between the upper blade mounting plate 84 and
the base 55. The springs 87 help ensure uniform movement of the
upper blade mounting plate 84 toward the base and provides a return
force to lift the plate after the cutting operation is completed.
The upper blade mounting plate 84 is fastened to the bottom of the
rack 62 by a mounting bolt 90 so that the plate moves with the
rack. Thus, when the operator pushes the handle 74 downward, this
force is transmitted through the pawl, ratchet gear, pinion gear
and rack to move the upper blade mounting plate 84 downward against
the upward force of the springs 87.
[0052] The upper blade mounting plate 84 is configured to receive a
removable and replaceable upper cutter base 92, as shown in FIGS.
11, 18, 19. The cutter base defines a channel 94 which receives the
upper blade mounting plate 84 to fix the side-to-side position of
the cutter base 92 relative to the mounting plate 84. Bolt holes 94
receive mounting bolts 95 (FIG. 11) that pass through aligned bolt
holes in the mounting plate 84 to fasten the cutter base 92 to the
mounting plate. It can thus be understood that different upper
cutter bases may be provided with the bone cutting apparatus 50 of
the present disclosure, each having the same channel 93 and bolt
holes 94 for attachment to the upper blade mounting plate 84.
[0053] As shown in FIGS. 18, 19, the cutter base 92 includes a
fixed blade 96 projecting from the underside of the cutter base.
The fixed blade incudes angled cutting edges 97 that converge to an
apex 98 at the center of the cutter base 92 and that are configured
to cut through bone. The cutter base 92 includes a plurality of
T-shaped slots 99 extending radially from the center of the base to
the outer perimeter of the base. The T-shaped slots are configured
to receive replaceable cutter blades 88, shown in FIG. 20. The
replaceable blades 88 include an upper rib 100 that is configured
to be slidably received within a T-slot 99 of the cutter base 92.
Each cutter blade 88 defines a cutting edge 101 configured to cut
through bone. In the illustrated embodiment, the cutter blades 88
are configured so that the cutting edges 101 are angled upward
toward the center of the cutter base, in contrast to the fixed
blade 96 in which the cutting edges 97 are angled downward toward
the center. Moreover, the cutting edges 101 of the replaceable
blades 88 are offset upward from the apex 98 of the fixed cutter
blade 96, as shown in FIG. 11. In a bone cutting operation, the
fixed blade 96 contacts the bone segment first, followed by the
replaceable blades 88 as the upper cutting assembly 80 is advanced
downward toward the bone segment. It can be appreciated that the
replaceable blades 88 can have cutting edges with different
configurations from the cutting edge 101 shown in the illustrated
embodiment. It can also be appreciated that different numbers of
blades lots 99 can be provided in the upper cutter base 92 to
receive different numbers of replaceable cutting blades 88. In the
illustrated embodiment, four replaceable blades are provided along
with the fixed blade 96 to provided six cutting edges 97, 101. The
blade slots 99 in this embodiment are offset at 60.degree.
intervals, but other angular offsets are contemplated, including
non-uniform angular offsets of the blades.
[0054] The upper cutting assembly 80 is driven toward the lower
cutting assembly 82 to cut a bone segment B positioned between the
two assemblies. The lower cutting assembly includes a cutting tray
110 that is removably mounted in the base 55, as illustrated in
FIG. 11. The base 55 defines aside opening cavity 113 with a ledge
112 for supporting the tray 110 above the cavity 113. The cavity is
sized to receive a removable collection container 115 (FIG. 24)
that can be placed below the tray and subsequently removed by a
handle 116. As shown in FIG. 23, the ledge 112 more than
180.degree., and preferably about 240.degree., so that the cutting
tray 110 is firmly retained within the base 55 during a cutting
operation. The cutting tray 110 can include a circular rim 120
configured to be seated on the ledge 112. The rim 120 can define
one or more alignment recesses 121 that are configured to receive
an alignment post 122 fastened to the base 55 (FIGS. 10, 13). The
alignment recesses and post fix the angular orientation of the
cutting tray 110 relative to the upper cutting assembly 80 and
upper cutting blades 88, 96. The cutting tray defines a plurality
of slots 125 converging to a center opening 126, as shown in FIG.
21. The slots 125 are arranged to receive a corresponding cutting
blade 88, 96 as the upper cutting assembly 80 is pushed through the
bone segment B. The slots thus ensure that the blades pass
completely through the bone segment to produce the requisite bone
fragments. It can be appreciated that the number and angular
arrangement of the slots 125 must coincide with the number and
angular arrangement of the cutting blades of the upper cutting
assembly 80. The cutting tray 110 defines a ledge 130 which
supports a cutting guard 132 (FIGS. 10, 11). The cutting guard can
be formed of a transparent material so that the cutting operation
can be observed.
[0055] A blade assembly assist component 140 is provided for
mounting the upper cutter base 92 to the blade mounting plate 84,
as shown in FIG. 26. As shown in FIG. 25, the assist component 140
includes a plurality of bosses 141 that define blade slots 142
between the bosses. The bosses 141 further define support surfaces
144 on which the upper cutter base 92 is placed with the cutting
blades 88, 96 extending into the slots 142. Alignment posts 104
(FIGS. 10, 26) are mounted in openings 103 in the cutter base 92
and are arranged to flank the sides of the upper blade mounting
plate 84. The alignment posts 104 ensure that the bolts 95 in the
mounting plate 84 are aligned with the bolt holes 94 in the upper
cutter base 92. As shown in FIG. 26, the upper cutter base 92 with
the full complement of cutting blades is placed on the blade
assembly assist component 140 with the cutting blades facing
downward into the slots 142. The assist component 140 is placed on
the cutting tray 110 with the mounting face of the cutter base 92
facing the upper blade mounting plate 84. The handle 74 is pushed
downward to move the mounting plate 84 downward toward the assist
component 140 until the bolts 95 contact the bolt holes 94 in the
cutter base 92. The bolts can then be tightened to draw the cutter
base 92 into engagement with the mounting plate 84. The pawl 71 is
then depressed to release the rack and pinion, and the knob 77 is
rotated counter-clockwise in FIG. 11 to raise the rack 62 and thus
the upper blade mounting plate 84 with the cutter base 92 and
cutting blades 88, 96 mounted thereto. The blade assembly assist
component 140 can then be removed from the cutting tray 110.
[0056] The bone cutting apparatus 50 can be used to cut a bone
segment B into several fragments, even if the bone segment is
frozen. The segment B is placed on the cutting tray 110 of the
lower cutting assembly 82, as shown in FIG. 11. The bone segment is
contained within the cutting guard 132. The upper cutting assembly
80 is outfitted with the desired cutting blades. As explained
above, manually pushing the handle 74 downward drives the upper
cutting assembly 80 downward toward the cutting tray 110. The
cutting blades 88, 96 contact the bone segment and cut through the
bone segment as the handle is pushed further downward. The
mechanical advantage or leverage provided by the length of the
handle 74 and the gear ratio between the rack 62 and pinion gear 64
allows a frozen bone segment to be cut into discrete fragments with
only manual force. The ratchet gear 70 and pawl 71 arrangement
allows the operator to push the handle down in intervals, rather
than having to cut through the bone in a single motion. Once the
cutting blades have passed through the bone segment, the pawl can
be depressed to release the ratchet and thus the pinion gear 64.
The springs 87 will push the upper blade mounting plate 84 upward
somewhat, with the operator rotating the knob 77 to lift the rack
62 and upper cutting assembly 80 to its maximum upward position
offset from the lower cutting assembly 82. The pawl 71 can be
re-engaged to the ratchet gear 70 to hold the upper cutting
assembly at this uppermost position ready for another bone cutting
operation.
[0057] The cutting tray 110 can be configured so that the bone
fragments fall into the collection container 115 positioned within
the cavity 113 in the base 55 beneath the upper cutting assembly.
For instance, the cutting tray can be configured like the base 47'
shown in FIG. 9D in which pie-shaped opening are defined between
the parts of the base forming the slots 47a' or receiving the upper
cutting blades. Alternatively, the cutting tray 110 can be lifted
from the base 55 and the bone fragments dumped into the collection
container 115.
[0058] The bone cutting apparatuses 10, 50 are configured to cut
through a bone segment, such as the bones of the pelvis, the long
bones and vertebral bodies. The force required to cut through such
bone is typically 800-900 lbf. The apparatuses of the present
disclosure provide a force transmission mechanism from the
user-operated handles 42, 74 to the upper cutting assemblies 20,
80. The force transmission mechanisms allow the typical operator to
generate up to 1000 lbf by applying less than 50 lbf to the handle,
which is well within the capability of most operators.
[0059] The present disclosure should be considered as illustrative
and not restrictive in character. It is understood that only
certain embodiments have been presented and that all changes,
modifications and further applications that come within the spirit
of the disclosure are desired to be protected.
* * * * *