FIELD OF THE INVENTION:
The present invention relates to a low friction surgical cutting system. More
specifically the present invention relates to a highly polished blade and cutting
guide assembly that prevents the abrasion between the blade and the cutting guide
slot thereby ensuring precision in cutting of bone.
BACKGROUND OF THE INVENTION:
Any orthopedic related surgery may require repositioning/partial removal of bone.
One of the commonly used tools to cut or prepare the bone is an oscillating saw.
This practice is more common in a joint replacement surgery. A joint replacement
surgery is a procedure in which the arthritic or dysfunctional joint surface is
replaced with an orthopedic prosthesis. Joint replacement is considered as a
treatment when there is severe joint pain or dysfunction is not alleviated by lessinvasive
therapies. Joint replacement surgery is becoming more common with knees
and hips replaced most often.
In a joint replacement surgery an oscillating saw blade is one of the various
instruments which are used for cutting the bone. The saw blades have teeth on their
cutting edge so as to facilitate cutting through the bone. During such a surgery, a
saw blade is fitted in a motor driven power tool to cut the measured section of the
bone. It is very important to ensure that, when a bone section is separated from rest
of the bone, the section is removed along very precise cut lines because the
substitute joint typically has a component that is designed to precisely fit in the
space defined by cut lines of the section of bone that is left in place.
The saw blade when connected to a motor driven power tool may oscillate in a back
and forth and sideways oscillating motion. To ensure precision in cutting the
measured section of the bone, the saw blade is used in conjunction with a metal
cutting guide that is fixed or pinned around the target anatomy so that the bone is
precisely cut along the lines of the slot.
The surgeon performs the surgical procedure by sequentially inserting the saw blade
in the slot. Once the blade is inserted in the slot, the saw is actuated by the power
tool. In this manner the surgeon is able to cut the bone along the precisely defined
lines along which the bone is to be separated. The blade cuts the bone where its
motion range is constrained by the walls of metal cutting guide slot. Such an
interface of the blade and walls of the cutting guide slot gives rise to a friction which
can increase the heat and debris, thereby affecting the outcome of the surgery. Any
debris generated increases the potential of Osteolysis and eventually a bone loss
around the affected region. Friction may also unnecessarily consume the power
supplied to the saw blade. The wearing of the blade can also widen the slot thereby
affecting the accuracy of the cut. This means that the slot and/or blade must be
repaired or replaced with a new one which in turn may again affect the accuracy
and also increase the overall cost. In the long run, excessive wear may affect the
accuracy of the cutting guide, in which case life of the cutting guide is compromised.
U.S. Patent No. 5507763, attempts to prevent wearing of the blade edges by forming
the blade such that the thickness of the blade adjacent to the lateral side walls is
reduced relative to the effective thickness of the body of the blade. Therefore when
the sides edges of the blades contact with the walls of the cutting guide slot, the
resultant thickness of deformed edges is less than or equal to the resultant thickness
of effective thickness of the blade body. In essence the occurrence of wearing of the
lateral side walls is planned for and compensated by the design to prevent
interference between the deformed edges and the cutting guide.
However, the aforementioned US Patent may be successful in delaying the effects of
the friction between the blade and the metal cutting guide slot but it does not
significantly override the wear of the blade-guide assembly caused due to the
friction over a longer and repetitive use.
Moreover, the abrasion of the blade against the walls of the metal cutting guide slot
may also release finer metal particles which if not removed may lead to Osteolysis.
The surgeons have to spend an extra time to remove such particles thereby
lengthening the procedure. However, to spend time on such an ancillary yet an
indispensible task not only poses a threat of infection to the exposed tissue but also
takes up the time for which the anesthesia may work on the patient.
During the surgery, the saw blade grazes against the surface of the cutting guide,
and then pulls away from the surface in a jerking motion. This jerking motion is
transferred from the blade through the hand piece into the hand of the surgeon
holding the saw. Such a jerking motion forces the surgeon to exert some muscle
control to hold the hand piece steady. Such a control may over a period of time
cause fatigue to the surgeon. Also most importantly such a jerking motion leads to
an increase in the chances of error during the surgery.
The damage caused due to the grazing of the saw blade with the walls of the cutting
guide slot may not be successfully prevented by the currently available techniques.
Therefore, a need arises to provide for a low friction cutting system for saw blades
used in surgeries which prevents generation of friction between the saw blade and
the cutting guide.
OBJECT OF THE INVENTION:
The main object of the present invention is to ensure accuracy and precision in the
cutting of the measured section of the bone during an orthopedic surgery.
It is another object of the present invention to reduce friction at the interface
between the blade and the walls of cutting guide slot used during an orthopedic
surgery.
It is yet another object of the present invention to prolong the life of the blade guide
assembly by using a highly polished blade and a multiple use disposable plastic
cutting guide.
It is another object of the present invention to prevent the release of metal particles
to prevent osteolysis by minimizing the friction at the interface of the blade and the
cutting guide slot
It is another object of the present invention to prevent the wear and tear of the blade
and guide assembly.
It is another object of the present invention to conserve the power used during the
working of the saw blade as the friction which is generated consumes unnecessary
power.
It is yet another object of the present invention to prevent the fatigue caused to the
surgeon due to the jerking motion of the saw on grazing with the cutting guide.
It is another object of the present invention to save the time of the surgeons while
performing the surgery who have to unnecessarily waste their time replacing or
repairing the damaged blade or damaged cutting guide or to remove dust, debris,
metal particles, etc. released during bone cutting.
SUMMARY OF THE INVENTION:
The present invention relates to a low friction surgical cutting system used during
orthopedic surgeries especially a joint replacement surgery.
Accordingly the present invention employs an oscillating saw blade which is made
of highly polished metal and has a highly smooth surface finish with no sharp edges
along the length and a cutting guide having a smooth low friction surface made of
multiple use disposable plastic. The multiple use disposable plastic cutting guides
could be of any shape. The low friction saw blade is connected to a motor driven
power tool to derive the power while cutting the bone. The end of the blade so
attached may have the attachment of any shape that is friendly to the power tool.
The edges of the saw are of lesser thickness than that of the blade so as to ensure
lesser impact around the edges of the blade. The mirror polished upper and lower
surfaces and the sides along the length of the blade minimize the friction generated
at the interface of the oscillating saw blade and the walls of the cutting guide slot.
The oscillating saw blade is used in combination with a multiple use disposable
plastic cutting guide such that the surface of the saw blade that is in contact with the
plastic cutting slot including but not limited to the upper and lower surfaces is
mirror polished to provide minimal friction during use. The edges of the blade as
well as the extreme corners of the guide slot may be rounded or have any other
shape that is not sharp.
Therefore, when the blade on being actuated through the power tool moves within
the plastic guide slot in a back-forth or sideways oscillating motion it results in
lesser frictional wear of the blade-guide assembly as a whole. Such an assembly
would prolong the life of the blade while not affecting the accuracy of the cut surface
generated, thus being a cost effective solution to the state of the art technology. The
most important advancement of the present invention is that it minimizes the
chances of friction generated at the interface of the blade and the cutting guide slot,
without the need of the highly mechanized metal blocks. Since the friction at the
interface of the blade and cutting guide slot is minimized, the accuracy of the cut is
eventually maintained. Such accuracy in turn helps in successfully fitting the
prosthetic/artificial bone which is cut precisely according to the measured section
that needs to be replaced.
The present invention also minimizes the sources of error in the accuracy ensured by
the cutting guide. In addition, the low friction minimizes the chances of release of
metal particles due to the abrasion of the blade with the walls of the cutting guide
slot and thus reduces any chances of osteolysis caused due such metal particles that
may be overlooked and left behind unattended on the bone or tissue.
Thus the invention relates to a novel low friction saw blade-guide assembly
comprising of smooth bodied saw blade with a plurality of teeth at one end with the
other end shaped to fit into a motor driven power tool capable of cutting a measured
section of the bone, and cutting guide having a body with rounded edges and a
cutting slot with low impact corners. The upper surface, lower surface and edges of
said smooth bodied saw blade are mirror polished to obtain a smooth bodied effect
to engage effortlessly with said smooth bodied cutting slot to make accurate cuts
during surgical procedure thereby minimizing friction generated at the interface
between the smooth bodied saw blade and the cutting guide, preventing osteolysis
caused by the release of metal particles due to friction at interface and prolonging
the life of said smooth bodied saw blade.
The smooth bodied saw blade is proportionately longer than its width and has a pair
of side walls extending from one end to the other end along its length in a manner
that the upper and lower blade surfaces extend between the side walls enabling
oscillation of smooth bodied saw blade within the slot of said cutting guide during
surgical procedure. The edges of said smooth bodied saw blade are of lesser
thickness than that of the blade so as to ensure lesser impact around the edges of the
blade. The cutting guide is made of disposable plastic reusable after sterilization
and capable of being made in any desired shape with or without holes in its body.
The low friction cutting guide is fixed or pinned around the target anatomy to
ensure that the bone is precisely cut along the lines of said cutting slot.
The smooth bodied saw blade moves within the plastic guide slot in a back-forth or
sideways oscillating motion when actuated by the connected power thus resulting in
less frictional wear of the blade-guide assembly as a whole.
BRIEF DESCRIPTION OF DRAWINGS:
Fig. 1 shows a perspective view of the blade-guide assembly.
Fig. 2 shows a cross-sectional view of the saw blade inserted in the cutting guide.
Fig. 3 shows a longitudinal view of the saw blade.
Fig. 4 shows a perspective view of the saw blade-cutting guide assembly fitted on a
measured section of the bone.
DETAILED DESCRIPTION OF THE INVENTION:
The present invention provides an oscillating saw blade (10) in combination with a
multiple use disposable plastic surgical cutting guide (11). Such an assembly of
oscillating saw blade (10) and the multiple use disposable plastic surgical cutting
guide is used during an orthopedic surgery especially a joint replacement surgery.
As best shown in Fig. 1, the saw blade (10) has one end (18) which may be round or
of any other shape and another end (19) having a plurality of teeth . The saw blade
(10) is made of highly polished metal having highly smooth surface finish with no
sharp edges along the upper & lower surfaces (22) and along the side length (14)~~
thereby reducing the friction at the interface of blade surface (17) and cutting guide
slot surface (13). The cutting guide (11) has a smooth surface made of multiple use
disposable plastic which could be of any shape and may also have holes (30) for
water irrigation or other pre/post cutting surgical steps. The low friction saw blade
(10) is connected to a motor driven power tool on its one end (18) at attachment (12)
which can be of any shape compatible with the motor driven power tool to derive
the power to cut the bone. The cutting guide slot (13) has low impact corners (16)
which may be specially coated to reduce the impact of moving upper and lower
blade surfaces (22). The mirror polished upper and lower surfaces (22) of the blade
minimize the friction generated at the interface between the oscillating saw blade
surface (17) and the walls (16) of the cutting guide slot (13). The side walls (16) of the
cutting slot may be parallel to the side length (14) of the blade or could be at an
angle such that it compensated accuracy data for the angle of oscillation created by
the blade (10) during operation.
As best shown in Fig. 2 the blade guide assembly wherein the oscillating saw blade
interface surface (17) is inserted in the multiple use disposable plastic cutting guide
slot (13) such that the surface of the saw blade (17) that is in contact with the plastic
cutting slot (13) including but not limited to the upper and lower surfaces (22) are
mirror polished to provide minimal friction during use. The side length of the blade
(14) as well as the side edges of the guide slot (16) may be rounded or have any
other shape that is not sharp.
Fig. 3 shows a longitudinal view of the saw blade(l0) wherein the surface of the
blade (22) including but not limited to upper and lower surfaces are mirror polished
to provide minimal friction during use. One end of the blade may be round(l8) or of
another shape and the other end having a plurality of teeth formed thereon (19). The
blade at one end (18) is attached to a motor driven tool wherein the attachment (12)
maybe of any shape which is compatible with the motor driven tool.
Fig. 4 shows a perspective view of the saw blade (10) and a multiple use disposable
plastic cutting guide (11) assembly fixed on to a measured section of the bone (23).
The saw blade (10) has teeth (19) on its cutting edge so as to facilitate cutting
through the bone (23). During the surgery, the saw blade (10) is fitted in a motor
driven power tool (24) at one end (18) through attachment (12) to cut the measured
section of the bone (23). The saw blade (10) when connected to a motor driven
power tool (24) may oscillate in a back and forth and/or sideways oscillating
motion. To ensure precision in cutting the measured section of the bone (23), the saw
blade (10) is used in conjunction with a multiple use disposable plastic cutting guide
(11) that is fixed or pinned via pin (31) around the target anatomy so that the bone
(23) is precisely cut along the lines of the cutting guide slot (13).
The surgical procedure is performed by sequentially inserting the saw blade (10) in
the cutting guide slot (13). Once the blade (10) is inserted in the cutting guide slot
(13), the saw blade (10) is actuated by the power tool (24) at the end (18). In this
manner the surgeon is able to cut the bone (23) along the precisely defined surface
with ease.
Example:
During a joint replacement surgery, the low friction cutting guide is fixed via a pin
on the measure section of the bone where a cut has to be made to fit in the artificial
joint component. Once it is in place the smooth bodied saw blade with a power tool
attached to its distal end is inserted into the cutting slot in the low friction cutting
guide to enable accuracy in the cutting of the bone part at the designated area. On
switching on the power tool, the smooth bodied blade enclosed in its side walls with
the multiple toothed cutting end aligned within the cutting slot oscillates within the
cutting slot smoothly. There are no metal fragments sheared off from the saw blade
during the cutting procedure due to the unique and novel structure and
arrangement of the components of the cutting guide. Due to this novel cutting
guide there is no danger of osteolysis occurring post surgery. Due to less wear and
tear, the cutting guide can be used multiple times after sterilization before disposal.
It is to be understood that the present invention is not limited to the embodiment
described above, but encompasses any and all embodiments within the scope of the
following claims.

We claim:
1. A novel low friction saw blade-guide assembly, said assembly comprising of :
smooth bodied saw blade (10) with a plurality of teeth at one end (19), the
other end (18) being shaped to fit into a motor driven power tool (24) capable of
cutting a measured section of the bone (23) and
cutting guide (11) having a body with rounded edges and a cutting slot (13)
with low impact corners (16),
wherein upper surface, lower surface (22) and edges (14) of said smooth
bodied saw blade (10) are mirror polished to obtain a smooth bodied effect to
engage effortlessly with said smooth bodied cutting slot (13) to make accurate
cuts during surgical procedure thereby minimizing friction generated at the
interface between said smooth bodied saw blade interface surface (17) and said
cutting guide slot interface surface (13), preventing osteolysis caused by the
release of metal particles due to friction at interface and prolonging the life of
said smooth bodied saw blade (10).
2. A novel low friction saw blade-guide assembly as claimed in claim 1, wherein
said smooth bodied saw blade (10) is proportionately longer than its width.
3. A novel low friction saw blade-guide assembly as claimed in claim 1, wherein
said smooth bodied saw blade (10) has a pair of side walls extending from one
end to the other end along its length (14) in a manner that upper and lower blade
surfaces (22) extend between said side walls thereby enabling oscillation of said
smooth bodied saw blade (10) within the cutting slot (13) of said cutting guide
(11) during surgical procedure.
4. A novel low friction saw blade-guide assembly as claimed in claim 1, wherein
cutting guide (11) said is made of disposable plastic reusable after sterilization
and capable of being made in any desired shape with or without holes (30) in its
body.
5. A novel low friction saw blade-guide assembly as claimed in claim 1, wherein
said low friction cutting guide (11) is fixed or pinned via a pin (31) around the
target anatomy to ensure that the bone (23) is precisely cut along the lines of said
cutting slot (13).
6. A novel low friction saw blade-guide assembly as claimed in claim 1, wherein
said smooth bodied saw blade (10) moves within the plastic cutting guide slot
(13) in a back-forth or sideways oscillating motion when actuated by the
connected power tool (24).
Dated this the 2gth day of November 2012.