WO2017106093A1

WO2017106093A1 - Surgical sagittal saw blade with stop teeth that are interleaved with the blade cutting teeth

Info

Publication number: WO2017106093A1
Application number: PCT/US2016/066145
Authority: WO
Inventors: Conor MAC AN TUILE
Original assignee: Stryker European Holdings I, Llc
Priority date: 2015-12-16
Filing date: 2016-12-12
Publication date: 2017-06-22

Abstract

A surgical saw blade with cutting teeth (78, 94) that extend forward from the blade body. At least one stop (86) also extends forward from the blade body. The stop tooth is formed with a face (88) that in located inward of the adjacent cutting tooth. The face of the stop tooth is shaped to limit the extent the adjacent cutting tooth can be pressed into the tissue against which the blade pressed.

Description

SURGICAL SAGI TTAL SAW BLADE WI TH

STOP TEE TH THAT ARE INTERLEAVED WI TH THE BLADE CUTTING TEE TH

FIELD OF THE INVENTION

[0001] This invention relates generally to surgical saw blades. More particularly, this invention relates to a sagittal surgical saw blade that, when pressed against bone, is relatively stable.

BACKGROUND OF THE INVENTION

[0002] In a surgical procedure, it is sometimes necessary to use a saw to remove tissue, including bone and cartilage. Often a powered saw is used to perform this procedure.

Attached to the saw is a saw blade. A drive assembly internal to the saw reciprocates the blade in a back and forth motion. Some blades are constructed to pivot back and forth,

oscillate, in the plane in which the blade is oriented. This type of blade is referred to as a sagittal saw blade. Other blades move back and forth along their longitudinal axes.

This type of blade is known as a reciprocating saw blade.

This type of blade is provided with teeth that extend

outwardly from a side edge of the blade body.

[0003] Often a sagittal saw blade is used to remove a section of bone as part of the procedure of fitting an

orthopedic implant to a patient. The sagittal blade is used to remove a section of the bone so that the remaining bone can receive the implant. Typically the surfaces of the implant that press against the remaining bone are planar. To ensure a good fit between the remaining bone and the implant it is desirable to have the surface of the bone against which the implant is placed, present a complementary planar surface to the implant. By extension, this means that when a sagittal blade is used to shape bone, the cut planes formed by the bone should, ideally, be planar in shape.

[0004] Known variates of sagittal saw blades have proven to be useful blades for forming planar cuts in bone.

Nevertheless, a problem can sometimes arise if, when a blade is pressed forward in the bone with an appreciable forward force. The combination of resistance of the bone to this force and the high speed back and movement of the blade can cause the blade to kick out of the plane of the cut. When this happens the resultant surface of the cut may not have planar shape that is most optimal for receiving the implant that is to be fitted to the bone. This means the surgeon may have to take additional action to ensure that the surface of the bone is properly shaped to receive the implant.

[0005] Another undesirable result of a blade kicking out of the plane of a cut, is that the blade may engage in

undesired movement adjacent the bone to which the blade is applied. During the course of this movement the blade may strike tissue adjacent the bone that is not intended to be cut. This tissue includes ligaments, arteries and nerves. Should the blade cut this tissue it can introduce unwanted complications into the procedure.

[0006] To reduce the likelihood that a blade kicks out of the cut plane, some surgeons find it best to apply a forward force to the blade that is less than the force the surgeon may otherwise want to apply. It has been found that by so

regulating the application of this force, the tendency of the blade to bounce out of the cut plane is reduced. A

disadvantage of this practice is that it slows the time it takes to form the cut. So slowing the cutting action runs contrary to a basic goal of modern surgery. A procedure should be performed as quickly as possible to minimize both the time the patient's normally covered tissue is open to the ambient environment and exposed to infectious agents and the time the patient is held under anesthesia.

SUMMARY OF THE INVENTION

[0007] This invention is directed to a new and useful surgical saw blade. The surgical saw blade of this invention has features designed to limit the extent to which, when a relative large force is placed against the blade, the blade teeth are pressed into the tissue the blade is intended to cut .

[0008] A surgical saw blade of this invention includes two type of teeth that are interleaved with each other. A first type of teeth are the blade cutting teeth. Each cutting tooth has a rake surface that terminates at a cutting edge. As the blade head is oscillated against the tissue the blade is intended to cut, the abutment of the cutting edge of tooth against the tissue causes the tooth to shear away, remove, the tissue against which the tooth is pressed.

[0009] A second type of tooth that extends forward from the body of a blade of this invention is a stop tooth. A stop tooth is not formed with any surfaces that define a cutting edge. Instead, a stop tooth is formed with a surface that, when pressed against tissue, resists further advancement against the tissue. The stop teeth are arranged so the most distal, most forward surfaces of these teeth are located a short distance behind the cutting edges of the adjacent cutting teeth.

[00010] In many, but not all, versions of the invention the cutting teeth and stop teeth alternate with each other.

[00011] When a blade of this invention is simultaneously pressed against tissue and oscillated, the first cutting tooth removes the tissue against which the tooth is pressed. The adjacent stop tooth limits the extent to which the cutting tooth is able to press against the tissue. This blocking action, limits the extent to which that cutting tooth as well as other cutting teeth adjacent the stop tooth that follow the stop are able to digs into the tissue against which the blade is applied. The limiting of the extent to which the cutting teeth dig into tissue reduces the resistive force the tissue presents in opposition to the advancement of the teeth.

Reducing this resistive force results in a like reduction in the likelihood that the resistive force the bone presents to the cutting teeth are so great they cause the that blade to kick out of the plane of the cut.

[00012] In many versions of this invention, the blade is constructed so as to be a sagittal saw blade. When the blade is so constructed, the cutting teeth and stop extend forward from the distal end of the body of the blade.

[00013] A blade of this invention typically has multiple cutting teeth and multiple stop teeth. In many versions of the invention in which the blade is sagittal saw blade, the blade actually has two sets of cutting teeth. A first set of cutting teeth are oriented so that when the blade pivots in a first direction, arbitrarily to the left, the teeth shear away the tissue against which the teeth are pressed. The second set of cutting teeth are oriented so that when the blade pivots in a second direction, arbitrarily to the right, the teeth shear away the tissue against which the teeth are pressed .

[00014] In some embodiments of the above version of the invention, at least one stop tooth is located between a tooth has the first orientation and an adjacent blade that has the second orientation.

[00015] Some blades of this invention are further to have one or more chip catchments. A chip catchment is void, a slot, that is located between two teeth and extends proximally into the blade to a located proximal to the teeth. The catchment functions as a void for receiving debris formed as a result of the cutting process. In some versions of the invention, the blade is formed so that chip catchment is located between a stop tooth and an adjacent cutting tooth.

BRIEF DESCRIPTION OF THE DRAWINGS

[00016] The invention is pointed out with particularity in the claims. The above and further features and benefits of this invention are understood from the following Detailed Description and the accompanying drawings in which:

[00017] Figure 1 depicts a sagittal saw blade of this invention attached to a sagittal saw;

[00018] Figure 2 is a plan view of a sagittal blade

constructed in accordance with this invention;

[00019] Figure 3 is a perspective view of the blade of Figure 2;

[00020] Figure 4 is a side view of the distal end of the blade of Figure 2;

[00021] Figure 5 is an enlarged plan view of the distal end of the blade of Figure 2;

[00022] Figure 6 depicts how scraping away of tissue, bone by the left most cutting tooth of the blade of Figure 2;

[00023] Figure 7 depicts how the left most stop tooth of the blade of Figure 2 limits the forward movement of the following cutting tooth;

[00024] Figure 8 is a perspective view of a first

alternative blade of this invention;

[00025] Figure 9 is a plan view of the distal end of the blade of Figure 8;

[00026] Figure 10 is a plan view of the distal end of a second alternative blade of this invention; [00027] Figure 11 is a plan view of the distal end of a third alternative blade of this invention;

[00028] Figure 12 is a plan view of the distal end of a fourth alternative blade of this invention; and

[00029] Figure 13 is an exploded view depicting how the blade of this invention may be incorporated into a sagittal blade cartridge and the blade head of the cartridge.

DETAILED DESCRIPTION

[00030] Figure 1 depicts surgical sagittal saw 30 to which a blade 60 of this invention is mounted. The saw 30 includes a pistol shaped body 32. The saw body 32 thus includes a handgrip 34. A barrel 36, also part of the body 34, extends proximally from the top of the handgrip 34. (Here,

"proximally" is understood to mean towards the surgeon holding the saw 30, away from the site to which the saw blade 60 is applied. "Distally is understood to mean away from the surgeon holding the saw 30 and towards the site to which the saw blade 60 is applied.) A neck 38 extends forward from the distal end of the barrel 36. A head 40 extends forward from neck 38.

[00031] A blade mount 42 is pivotally mounted to the head 40. Blade mount 42 includes components for releasably holding the blade 60 to the head. One of these components is a tab 44 that extends outwardly from the base of the head 40 and that can be rotated back and forth in an arc around the head. The structure of the components integral with the saw that releasably hold the blade 60 to the saw is not part of this invention. An understanding of one such assembly can be found in PCT Pub. No. WO 2007/011542 Al/US Pat. Pub.

US 2007/0016238 Al , the contents of which are incorporated herein by reference. [00032] A motor, represented by a dashed cylinder 44, is mounted in the barrel 36. A transmission assembly, not illustrated and not part of the present invention, transfers the rotational movement of the motor rotor to a motion that oscillates the blade mount 42 back and forth. The movement of the blade mount 42 results in a like back and forth movement of the attached blade 60. The blade 60 thus oscillates around an axis that extends in and out of the plane of the blade as depicted in Figure 2.

[00033] The depicted saw 30 is understood to have a DC powered motor. A battery 46 is attached to the butt end of the handgrip 34. The battery supplies the current used to apply an energization signal to the motor. A manually

actuated trigger 48 projects distally forward from the portion of the handgrip approximately 1 to 2 cm below the neck 38. Internal to the handgrip is a control module, not illustrated and not part of the present invention. The control module includes at least one sensor that monitors the actuation of the trigger 48. Based on the extent to which the trigger 48 is depressed, the control selectively controls the application of the energization signal to the motor. The control module regulates the application of the application single to cause the motor to run at a speed that results in the desired back and forth pivotal motion of the blade 60 in the sagittal plane desired by the surgeon using the saw and blade. One such control module that can be incorporated in the saw is

disclosed in PCT Pub. No. WO 2007/002180 A2/US Pat. Pub. No. US 2007/0085496 Al , the contents of which are incorporated herein by reference.

[00034] A saw blade 60 of this invention as seen best in Figures 2-4, includes a planar blade body 64. The proximal end of blade body 64 is formed with features that facilitate the releasable engagement of the blade 60 with the features integral with the saw 30 that releasably hold the blade to the saw. In the depicted version of the invention, one of these features is tab 62 that extends proximally from the proximal end of the blade body 64. Tab 62 is centered on the proximal to distal longitudinal axis that extends along the blade body 64. The tab 62 has a side-to-side width that is less than the width of the blade body 64. A second feature formed in the blade body 64 that facilitates the releasable

attachment of the blade 60 to the saw 30 is an opening 68 that extends top to bottom through the opposed major faces of both the tab 62 and body 64. The depicted opening 68 is elongated opening the major axis of which is in registration with the longitudinal axis of the blade body 64. Opening 68 is shaped so the opposed proximal and distal sections of the opening a circular in shape, individual opening sections not identified. The opening has an intermediate section that extends between the proximal and distal sections. The side-to-side width of the opening intermediate section is less than the diameter of the opening proximal and distal sections. Blade 60 is further formed so that tab 62 has a gap 66 that extends forward from the proximal end of tab. The gap 66 opens into the distal section of opening 68.

[ 00035 ] A neck 72, seen best in Figures 4 and 5, also part of blade 60, extends forward from the distal end of the blade body 64. Each major face of the neck 72 is recessed inwardly relative to the adjacent major face of the blade body 64.

Blade neck 72 thus has a top-to-bottom thickness that is less than that of the blade body 64. The neck 72 thus has face surfaces that are recessed inwardly relative to the adjacent face surfaces of the blade body 64. Blade 60 of this

invention also includes a head 74 that is contiguous with and extends distally forward from the neck 72. Each major face of the head 74 is planar with the proximally adjacent major face of the blade body 64. The blade head 74 thus has a top-to- bottom thickness that is greater than that of the neck 72.

[00036] Plural teeth 78, 86 and 94, also part of the blade 60 are formed in the head 74. Since the teeth are formed as part of the blade head 74, the teeth have a

thickness greater than that of the neck 72.

[00037] Blade 60 of this invention has two types of teeth, cutting teeth 78 and 94 and stop teeth 86. As implied by their name, the cutting teeth 78 and 94 are formed so that when the blade head is oscillated against tissue, typically bone, the cutting teeth scrape away, remove the tissue against which the teeth are pressed. In the depicted version of the invention, each cutting tooth 78 and 94 has a rake surface 80, two rake surfaces identified, and a clearance surface 84, two clearance surfaces identified. Each rake surface 80 extends along a plane that is at a relatively shallow acute angle relative to the longitudinal axis through the blade. Each clearance surface extends along a plane that is at relative large acute angle relative to the longitudinal axis through the blade. The rake surface 80 and clearance surface 84 of each tooth 78 or 94 meet at what is referred to as the cutting edge 82 of the tooth, two cutting edges identified. Blade 60 is constructed so that teeth 78 are on the left side of the longitudinal axis through the blade. Each tooth 78 is formed so that as the rake surface 80 extends forward from the proximal end of the head 74, the surface 80 angles to the left. Teeth 94 are located to the right of the longitudinal axis through the blade 60. Each tooth 94 is formed so that, as the rake surface 80 extend forward from the base of the head, the surface 80, the surface angles to the right.

Relative to the longitudinal axis through the blade 60, each tooth 78 is symmetric with respect to one of the teeth 94. [00038] The stop teeth 86 are shaped to limit the extent to which the adjacent cutting teeth can be pushed into tissue. In the depicted version of the invention, each stop tooth 86 has a distally directed face 88 that is semicircular in shape. In Figure 5, the edge of a single one of the faces 86 of a stop tooth is identified. Blade 60 is further designed so the crest 90, the most distal section of the face 86 of a stop tooth 86 is located proximal to the cutting edge 82 of the adjacent cutting tooth. More particularly, it should be understood that, since the a sagittal saw blade moves back in forth in an arc, each cutting edge and stop tooth crest 90 travels back and forth in its own arc. These arcs are

concentric with each other. Blade 60 is shaped so the arc in which the crest 90 of a stop tooth 86 travels is located inwardly of the arc in which the cutting edges of the adjacent cutting teeth travel. In many versions of the invention, the blade is shaped so the arc in which the crest of stop tooth travels is located a minimum of 0.01 mm inward of the arc in which the cutting edges of the adjacent cutting teeth travel. Typically, a blade of this invention is designed so the maximum spacing of the arc of travel of the crest of a stop tooth and the arc of travel of the cutting edge of the

adjacent cutting teeth is 0.5 mm.

[00039] The cutting teeth 78 and 94 are seen to have a transition surface 85, a single surface 85 is identified.

Each transition surface 85 extends proximally from the end of the tooth clearance surface that is spaced from the tooth cutting edge. Each transition surface 85 curves into and transitions to become the distally directed face 88 of the adjacent stop tooth 86

[00040] Blade 60 is shaped so that a stop tooth 86 is located between each pair of adjacent cutting teeth 78 or 94. One stop tooth 86 is centered on the longitudinal axis of the blade 60. This center located stop tooth 86 is thus located between the rightmost cutting tooth 78 and leftmost cutting tooth 94. The cutting teeth 78 and 94 are seen to have a transition surface 85, a single surface 85 is identified.

Each transition surface 85 extends proximally from the end of the tooth clearance surface that is spaced from the tooth cutting edge. Each transition surface 85 curves into and transitions to be become the distally directed face 88 of the adjacent stop tooth 86

[00041] The blade 60 is further formed to have four

notches 98, one notch identified. Each notch 98 is located between a stop tooth 86 and the following cutting tooth 78 or 94. Thus, there are no notches located on either side of the center located stop tooth 86. Each notch 98 extends through the blade head 74. Each notch 72 extends partially into the blade neck 72.

[00042] Blade 60 is prepared for use by inserting the proximal end of the blade body 64 in the blade mount 42. The latching assembly integral with the saw 30 is set to

releasably hold the blade 60 to the blade mount so the blade oscillates, pivots, with the blade mount. When the surgeon wants to remove tissue with the blade, the surgeon depresses the trigger 48. The control module, in response to sensing the depression of the trigger 48, supplies an energization current to the motor. The resultant actuation of the motor results in the back and forth oscillation of the blade mount and, by extension, the saw blade 60.

[00043] To remove bone, the surgeon directs the blade head 74 towards the tissue, typically bone, that is to be cut. Figures 6 and 7 depict what occurs as a result of the blade oscillating, pivoting, to the left of the longitudinal axis through the saw 30. From Figure 6 it can be seen that during this movement of the blade, the left most cutting tooth 78 is pressed against bone and moves to the left. The tooth being pressed into the bone and being displaced left, shears

material away from the face of the bone. At this time there may be a small gap between bone and the face 88 of the stop tooth 86 immediately to the left of this tooth 78. In Figure 6 the size of this gap is exaggerated for purposes of

illustration .

[00044] As a result of the forward force applied by the surgeon through the saw 30 to the blade 60, this stop tooth 86 is immediately pressed against the face of the bone as seen in Figure 7. In Figure 7 it appears the face of cut bone is linear in shape. In actuality, given that the blade 60 pivots in an arc, the face of the cut is arcuate. Owing to the shape of the stop tooth 86, the stop tooth limits the extent to which the adjacent cutting tooth, can press into bone. In Figure 7, this is depicted by the abutment of the stop teeth limiting the extent to which the right side cutting tooth 78 presses into tissue. In actuality, in this version of the invention, the stop tooth on the left also limits the extent to which the left side cutting tooth 78 can also press into tissue .

[00045] This limiting of the extent to which the cutting teeth 78 press into bone in turn, limits the depth of the section of the bone against which the rake surface 80 of the following cutting tooth 78 is pressed. The limiting of the depth of the this bone face against which the following cutting tooth limits is pressed limits the extent to which the bone imposes a resistive force in opposition to the continued sweep of the bone. The limiting of this force in opposition to the movement of the cutting tooth 78 causes a like

reduction in the likelihood that the presence of this force will cause the blade 60 to kick out of the plane of the cut. This reduced kick enhances surgeon control of the cutting process .

[00046] Thus, when using blade 60 of this invention, the surgeon does not have to exert an appreciable amount of mental thought or physical control to regulate the force with which the blade is pressed against the bone to reduce the incidence of blade kick out.

[00047] Further blade 60 of this invention is that the blade is well suited to be manufactured out of carbide.

Presently, many sagittal saw blades are manufactured out of stainless steel. While a stainless steel blades generally work well, they are prone to bowing. Bowing is the flexing or curving of the blade body. Bowing can occur when the distal end, the teeth of the blade are subjected to an appreciable resistive force. If the bowing is appreciable, the blade may start to form a cut outside of the desired cut plane.

Accordingly, there is an interest in fabricating surgical sagittal saw blades out of carbide. A benefit of forming the forming the blade out of carbide is that it is appreciably stiffer than stainless steel. This means that if a steel blade and an identically shaped blade formed from carbide are subjected to the same load, resistance, the carbide blade will, in comparison to the steel blade, undergo less bowing.

[00048] A disadvantage associated with forming a blade out of carbide, in comparison to steel, is that in response to the same load, a carbide blade is more prone to shearing,

fracturing. This is especially true of the teeth of the blade as these are some of the most fragile parts of the blade.

However, as described above, blade 60 of this invention is designed to limit the depth of the cut of any one tooth in a single sweep of the blade. This limits the side loading the tooth is exposed to during the cutting process. The limiting of this side loading reduces the likelihood that the tooth, especially a tooth formed from carbide, will be subjected to some much stress that the tooth with shear from the rest of the blade. Accordingly a surgical sagittal saw blade of this invention formed carbide will have a blade body that is less likely to bow than a blade formed from stainless steel and teeth that are collectively shaped to minimize the likelihood that, in the cutting process in one tooth will be subjected to so much stress that the tooth will shear off the rest of the blade .

[00049] Blade 60 is further designed so that at least some of the debris generated during the cutting process flow into notches 98. The debris flow from the notches 98 into the spaces above the opposed major faces of the blade neck 72. From these spaces the debris flow out of the sides of the blade 60. This minimizes the extent to which the debris build up adjacent the face of the uncut bone. This minimization of debris build up adjacent the bone to be cut results in a like reduction of the force that the saw needs to output in order to sweep these debris away from the bone during the cutting process. The reduction in the need to apply this force, means more of the force output by the saw is able to go directly into the bone cutting process.

[00050] Figures 8 and 9 illustrate an alternative blade 120 of this invention. Blade 120 includes a blade body 124 with a tab 122. The proximal end of blade body 124, including tab 122, are identical in shape and function to the proximal end of blade body 124 and tab 124. One difference between blade bodies 64 and 124 concerns their widths. The side to side width of the middle of blade body 64 is less than the same dimension across the proximal end of the blade body. The side to side width of middle of blade body 124 is greater than the same dimension across the proximal portion of the blade body 124. This difference is not material to the present invention .

[00051] The blade 120 is formed so that plural teeth 136, 146 and 154 extend forward from the distal end of the blade body 124. Teeth 136 and 154 are the cutting teeth. Each cutting tooth 136 and 154 has a rake surface 138 and a

clearance surface 142, one of each surfaces 138 and 142 identified. The rake surface 138 and the clearance

surface 142 of each tooth 136 or 154, meet to define the cutting edge 140 of the tooth, one cutting edge identified. The cutting teeth 136 and 154 are shaped to have rake

surfaces 138 that lie in planes parallel to the longitudinal axis through the blade 120. Blade 120 is further designed so that cutting teeth 136, three of five teeth 136 identified, have rake surfaces 138 that are directed toward the left side of the blade 120. Cutting teeth 154, three of five teeth 154 identified, have rake surfaces 138 that are directed towards the right side of the blade 120.

[00052] The blade 120 is further formed to have a chip catchment 162. Chip catchment 162 is a void that extends completely through the blade body 124 at a location between 0.3 and 2.0 cm distal to the teeth 136, 146 and 154. There is also an opening 160 that extends proximally rearward from the distal end of the blade 120. Both the opening 160 and chip catchment 162 are symmetric with respect to the longitudinal axis of blade 120. The opening 160 opens into the chip catchment 162. The side to side width of the opening is less than the side width of the chip catchment.

[00053] Blade 120 is formed so the left most tooth is a cutting tooth 136. The remaining cutting teeth located to the left of opening 160 in Figure 9 are cutting teeth 154. The rightmost cutting tooth is a cutting tooth 154. The remaining cutting teeth to the right of opening 160 are cutting teeth 136.

[00054] Teeth 146 are the stop teeth of blade 120. Each stop tooth 146 has a shape similar to that of the previously described stop teeth 86. Two stop teeth 146 extend distally forward from each side of the opening 160. To the left of opening 160, a first stop tooth is located between the two left most cutting teeth 154. The second stop tooth 146 is located between the two right most cutting teeth 154. To the right of the opening 160, a first stop tooth is located between the two left most cutting teeth 136. The second stop tooth 146 is located between the two rightmost cutting teeth 136.

[00055] The blade 120 is also formed with longitudinally extending indentations, dubs 166, two dubs identified, that extend proximally from the distal end of the blade. Dubs 166 extend over the teeth 138, 146 and 154 and a short distance over the adjacent portion of the blade body 124. The two dubs 166 closest to opening 160 on each side of the opening open into the chip catchment 162.

[00056] Blade 120 is mounted to the saw 30 in a manner identical to that used to releasably hold blade 60 to the saw. Blade 120 is used to cut tissue the same way blade 60 is used for the same purpose.

[00057] When a sagittal saw blade such as blade 120 is oscillated, the blade sweeps along an arc spaced from the centerline of the saw that is usually less than 5° and often 3° or less. Consequently owing to the dimensioning of the saw, when the saw blade sweeps left, the left most cutting tooth 136 sweeps against, shears away, a first arc of tissue. Simultaneously, the cutting teeth 136 to the right of

opening 160 sweep against a second arc of tissue. These two arc of tissue against which the cutting teeth 178 are pressed have an overlap that is typically no more than 1°. During this sweep of the blade 120, the stop teeth 146 to the right of opening 160 limit the extent to which the cutting teeth 136 to the right of the opening are able to press into the bone being cut. This limits the resistive force to which these cutting teeth are exposed. Again, this limits the likelihood that the blade 120 of this invention will be exposed to resistive forces that cause the blade to kick out of the plane of the cut.

[00058] During a right sweep of a single back and forth oscillatory cycle, the rightmost cutting tooth 154 presses against an arcuate section of bone that substantially overlaps the section of bone the right side cutting teeth 136 press against during a left sweep. Simultaneously, the cutting teeth 154 to the left of opening 160 press against an arcuate section of bone that substantially overlaps the section of bone against which the left most cutting tooth 136 pressed against in the immediately preceding half-cycle. During this half-cycle of blade movement, the stop teeth 146 to the left of opening 160, limit the extent to which the cutting

teeth 154 on the same side of the opening are able to press into the bone. Again, this limits the resistive force to which these cutting teeth 154 are exposed.

[00059] During the cutting of bone with blade 120, the debris generated by the cutting process flow into the

dubs 166. The debris that flow into the dubs 166 integral with the chip catchment 162 flow into the chip catchment.

This dubs 166 by functioning as a flow path for the debris, reduce the extent to which the debris build up between the cutting teeth 136 and 154 and the bone being cut.

[00060] Figure 10 illustrates the distal end of a second alternative blade, blade 180, of this invention. Blade 180 has blade body 182 the distal end of which is seen in the Figure. A neck 184 that has a smaller width than the blade body 182 extends forward from the body. Blade body 182 can be considered analogues to the first described blade body 64. Neck 184 is analogues to neck 72. The blade 180 has a

head 186 similar to head 74 of blade 60. Thus, the top-to- bottom thickness of head 186 is equal to the same thickness of the blade body 182. This the head 186 has a thickness greater than the thickness of neck 184.

[00061] The blade head 186 is formed with plural teeth 190, 198 and 202 that project distally forward. Teeth 190 and 202 are the cutting teeth of the blade. Each cutting tooth 190 and 202 has a rake surface 192 and clearance surface 196 that meet to define the cutting edge 184 of the tooth. To minimize drawing complexity, only a single rake surface 192, cutting edge 194 and clearance surface 196 are identified. Cutting teeth 190 are shaped so as to have rake surfaces that are directed to the left side of the blade. Cutting teeth 202 are shaped to have cutting surfaces that are directed to the right side of the blade.

[00062] Blade 180 is shaped so that cutting teeth 190 and 202 alternate with each other along the side to side length of the blade head 186. The leftmost tooth is cutting tooth 190a. The rightmost cutting tooth is cutting tooth 202c. Cutting teeth 190 and 202 are further shaped so the distances the teeth extend forward from a fixed line perpendicular to the blade longitudinal axis varies along the length of the blade. Arbitrarily the proximal end of the blade head 186 can be considered this fixed reference line. Thus cutting

tooth 202a, the cutting tooth immediately to the right of cutting tooth 190a, has a cutting edge that is located forward of the cutting edge of cutting tooth 190a. Cutting

tooth 190b, the cutting tooth immediately to the right of cutting tooth 202a, has a cutting edge that is located forward of the cutting edge of cutting tooth 202a. Cutting teeth 190a, 202a and 190b are located to the left of the

longitudinal axis of the blade 120.

[00063] Cutting tooth 202b, which is located to right of the longitudinal axis is the cutting tooth immediately to the right of cutting tooth 190b. Cutting teeth 190b and 202b are symmetric with respect to the longitudinal axis and therefore have cutting edges that are located the same distance forward from the reference line. Cutting tooth 190c is the cutting tooth located to the right of cutting tooth 202b. Cutting teeth 190c and 202a are symmetric around the longitudinal axis. Cutting tooth 190c thus has a cutting edge that is located proximal to the cutting edge of cutting tooth 202b. Cutting tooth 202c is the cutting tooth located immediately to the right of cutting tooth 190c. Cutting teeth 190a and 202c are symmetric around the longitudinal axis. Cutting

tooth 202c has a cutting edge 194 that is located proximal to the cutting edge of cutting tooth 190c.

[00064] Teeth 198 are the stop teeth of the blade 180. The stop teeth 198 have the same semi-circular shape as stop teeth 86 and 146. Stop tooth 198a is located between cutting teeth 190a and 202a. The crest of stop tooth 198a is

typically located proximal to the cutting edge of stop

tooth 202a. In Figure 10 the crest of stop tooth 198a is shown being distal to the cutting edge of cutting tooth 190a. This design feature may not be present in all versions of the invention. Stop tooth 198b is located between cutting

teeth 202a and 190b. Stop tooth 198b has a crest that is proximal to the crest of both cutting teeth 202a and 190b. Stop tooth 198c is located between cutting teeth 190b and 202b. Blade 180 is formed so that the stop tooth 198c is symmetric around the blade longitudinal axis. The crest of stop tooth 198c is proximal to the cutting edges of both cutting teeth 190b and 202b. Stop tooth 198d is located between cutting teeth 202b and 190c. Stop tooth 198d is symmetric around the blade longitudinal axis with stop

tooth 198b. Stop tooth 198e is located between cutting teeth 190c and 202c. Stop tooth 198e is symmetric with stop

tooth 198a.

[00065] Blade 180 is further formed so there is a gash 206 on each side of stop tooth 198b and on each side of stop tooth 198d. Each gash 206, intersects the blade neck 184. Gashes 206 are analogous to notches 98.

[00066] During a left sweep of blade 180, cutting

teeth 190a, 190b and 190c, are simultaneously pressed into the bone and move to the left. Thus, teeth 190a, 190b, and 190c, simultaneously shear away bone from different arcuate sections of the surface against which the blade 180 is pressed.

Simultaneously, each of the stop teeth 198a through 198e are pressed against the newly exposed face of the bone. Thus, the plural stop teeth cooperate to limit the extent to which the cutting teeth 190a, 190b and 190c are pressed into the bone.

[00067] During a right sweep of blade 180, cutting

teeth 202a, 202b and 202c are simultaneously pressed into the bone and move to the left. Teeth 202a, 202b, and 202c, simultaneously shear away bone from different arcuate sections of the surface against which the blade 180 is pressed.

Simultaneously, each of the stop teeth 198a through 198e are pressed against the newly exposed face of the bone. Thus, the plural stop teeth cooperate to limit the extent to which the cutting teeth 202a, 202b and 202c are pressed into the bone.

[00068] A third alternative blade, blade 220 is now

described by reference to Figure 11. Blade 220 includes the previously described blade body 182 and neck 184.

[00069] Blade 220 has cutting teeth 230 essentially

identical in shape to cutting teeth 190. The blade 220 also has cutting teeth 240 essentially identical in shape to cutting teeth 202. Not identified are the rake surfaces, the cutting edges and the clearance surfaces of the cutting teeth 230 and 240. The blade 220 is constructed so each of the cutting teeth 230 are located to the left of the blade longitudinal axis. The leftmost cutting tooth 230, cutting tooth 230a, is shaped to have the most proximally located cutting edge of the cutting teeth 230. Cutting tooth 230b, which is the cutting tooth immediately to the right of cutting tooth 230a has a cutting edge that is located distal to the cutting edge of tooth 230a. Cutting tooth 230c which is the cutting tooth immediately to the right of cutting tooth 230b has a cutting edge that is located distal to the cutting edge of tooth 230b.

[00070] Cutting teeth 240 are located to the right of the longitudinal axis Cutting tooth 240a is symmetric with respect to cutting tooth 230c. Cutting teeth 230b and 240b are symmetric with respect to each other. The rightmost cutting tooth, tooth 240c, is symmetric with respect to the leftmost cutting tooth, tooth 230a.

[00071] Blade 220 is further formed to have plural stop teeth 234. Stop tooth 234a is located between cutting

teeth 230a and 230b. Stop tooth 234a has a crest that is located distal to the crest of tooth 230a and proximal to the crest of tooth 230b. Stop tooth 234b is located between cutting teeth 230b and 230c. Stop tooth 234b has a crest that is located distal to the crest of tooth 230b and proximal to the crest of tooth 230c. Stop tooth 234c is located between cutting teeth 230c and 240a. Stop tooth 234c has a crest that is located proximal to the cutting edges of teeth 230c and 240a. Stop tooth 234d is located between cutting teeth 240a and 240b. Stop teeth 234b and 234d are symmetric with respect to the longitudinal axis of the blade. Stop tooth 234e is located between cutting teeth 240b and 240c. Stop teeth 234a and 234e are symmetric with respect to the longitudinal axis of the blade

[00072] While not identified, it is seen in Figure 11 that blade 220 is formed with gashes 206. The gashes are located between the follow pairs of teeth: 234a and 230b; 234b and 230c; 240a and 234d; and 240b and 234e. Thus in this version of the invention a gash is located between a stop tooth and the adjacent cutting tooth with a cutting edge that is located forward of the stop tooth.

[00073] Blade 220 operates in the same general manner as blade 180. When the blade 220 sweeps left, cutting teeth 230 simultaneously are pressed against and shear away bone. When the blade 220 sweeps right, cutting teeth 240 simultaneously are pressed against and shear away bone. Regardless of the direction of the sweep, the plural stop teeth 234 press against the bone. Stop teeth 234 thus limit the extent to which the cutting teeth are pressed into the bone. This limits the amount of resistive force the bone presents in opposition to the sweep of the cutting teeth.

[00074] Blade 250, a fourth alternative blade, is

illustrated in Figure 12. Blade 250 has essentially the same components as blade 180 of Figure 10. A difference between blades 180 and 250 is that, instead of gashes 206, blade 250 is formed with gashes 258. Gashes 258 extend proximally deeper into blade neck 184 than gashes 206.

[00075] The above are directed to specific versions of this invention. Alternative versions of the invention may have features different from what has been described.

[00076] For example, the cutting teeth may have geometries different from what has been described. Thus, an alternative saw of this may have cutting teeth one or more which includes plural rake surfaces and cutting edges. This type of tooth is shaped so that when the blade sweeps in one direction a first one of the rake surfaces scrapes against the bone against which the blade is pressed. When the blade sweeps in the opposed direction, the second rake surface scrapes against the bone. Likewise it should be understood the blade of this invention is not limited to blade with teeth having a specific range of rack angles or a specific range of relief angles.

[00077] Likewise, a single blade of this invention may have cutting teeth with different shapes.

[00078] Similarly, the shape of the stop teeth may vary from what has been described. In an alternative version of the blade of this invention, the most distal section of a stop tooth, the crest of the tooth, may not be a single line portion of a curved surface. In an alternative version of the invention, the crest may be a linear section of the face of the stop tooth. It should be understood that in versions of the invention in which the crest of a stop tooth is a linear section of the face of the tooth invention, the transition portions of the face that extend proximally from the crest are typically rounded.

[00079] A single blade of this invention may have stop teeth with different shapes. Similarly there is no

requirement that the teeth immediately to the right and left of a stop tooth be a cutting tooth. An alternative blade of this invention may include two or more stop teeth followed by one or more cutting teeth. Likewise, this invention is not limited to blades where the outer teeth are always cutting teeth. An alternative version of this invention may be constructed so on one or both sides of the blade the outer tooth is a stop tooth.

[00080] It should also be understood that the blade of this invention is independent of the features at the proximal end of the blade employed to releasably connect the blade to the saw that oscillates the blade. Thus, this blade is not limited to the blade having the described tab 62 and

opening 68. Other blades may have plural opening for

receiving members that releasably hold the blade to the attached saw. Some blades my not have any openings to hold the blade to the saw employed to oscillate the blade. For example, the side surfaces of these blades may have inwardly directed scallops. These scallops define voids for receiving the fastening components integral with the saw that hold the blade to the saw. Alternatively, the features that facilitate the coupling of the blade to the saw may consist of ribs or other protrusions that extend out of the plane of the blade body. In still other versions of the invention, providing the proximal section of the blade body with specific dimensions may be the only features required to facilitate the releasable coupling to the saw 30 used to oscillate the blade.

[00081] Likewise, while most sagittal saw blades have planar bodies, this invention is not limited to blades having this form of body. There may be reasons why either body of the blade or the neck portion is not planar in shape.

[00082] As depicted in Figure 13, it is within the scope of this invention that the features that facilitate the

releasably coupling of the blade to a saw for oscillation may include features that facilitate the extension of one or more drive rods from the blade. In Figure 13 the depicted assembly is a blade cartridge 270. The blade cartridge 270 includes a lower plate 272 and an upper plate 276 that are welded

together. Collectively the lower and upper plates 272 and 276, respectively, for the static bar of the cartridge 270.

[00083] The blade, when part of the cartridge 270 typically referred to as a blade head 292, is mounted between the plates 272 and 276. The blade head 282 includes a base 294. The base 294, analogues to the body 64 of blade 60 is the portion of the blade disposed between the plates 272 and 276. The proximal end of the base 294 resets against and pivots around a boss 274, shown as being part of the lower plate 272 is static with respect to the plates. Forward of the

base 294, the blade head includes a crown 296. The crown 296 is analogues to the blade head 74 of blade 60. The crown 296 is formed so as to have the combination of cutting teeth and stop as described and illustrated with respect to the other versions of the invention. As the teeth are similar to the previously described cutting teeth and stop teeth, these teeth are not identified in Figure 13. It should be understood that the crown 296 and, more particularly, the cutting teeth of the crown head have a top to bottom thickness greater than that of the base 294 of the blade head 292. Specifically the teeth having a thickness so the kerf cut by the teeth can receive at least the adjacent distal section of the bar of the

cartridge 270.

[ 00084 ] The cartridge 270 also includes at least one drive rod 280. In Figure 13 two drive rods 280 are seen extending proximally from the opposed proximal ends of the base 294 of the blade head 292. The drive rods 280 are pivotally

connected to the blade head base 294 by pivot pins 282. The pivot pins 282 extend through holes 295 formed in the blade head base 294. The proximal ends of the drive rods are formed with openings 284, one opening identified. Openings 284 are dimensioned to receive pins integral with the saw to which the cartridge 270 is attached. The actuation of the motor

integral with the saw results in the back and forth motion of the pins. The motion of the pins causes the drive rods 280 to engage in opposed simultaneous proximal to distal reciprocal motion. This reciprocal movement of the drive rods 280 oscillates the blade head 292 around boss 274. [00085] A more complete understanding of cartridge 270 and the saw that is used to actuate the blade head can be obtained from US Pat. Pub. No. US 2007/0119055 Al/PCT Pub. No.

WO 2007/030793 A2 , the contents of which are incorporated herein by reference.

[00086] Thus, in this version of the invention, the feature of the blade that facilitates the releasably coupling of the blade to the saw that oscillates the blade is the at least one drive rod 280 that pivots the blade head back and forth.

[00087] It should be understood that features of the different versions of the invention may be combined. For example, a blade may have the cutting teeth 78 and 94 of blade 60 and the opening 160 and catchment 162 of blade 120.

[00088] This interleaved cutting teeth and stop teeth of this invention may also be part of a reciprocating blade. A reciprocating blade has teeth that project outwardly from the side of the blade. A reciprocating blade is attached to a reciprocating saw. The reciprocating saw oscillates,

reciprocates, the blade back and forth, proximally to distally along the proximal to distal longitudinal axis that extends through the blade.

[00089] Accordingly, it is an object of the appended claims to cover all such variations and modifications that come within the true spirit and scope of this invention.

Claims

What is claimed is:

1. A saw blade (60, 120, 180, 220, 250, 294) for use with a powered surgical saw (30), said saw blade including: a blade body (64, 124, 182) having opposed proximal and distal ends and, adjacent the proximal end, features for (62, 66, 68, 122) for releasably hold the blade to a blade mount (42) integral with the saw so that the saw is able to

reciprocate the blade; and

cutting teeth (78, 94, 136, 154 190, 202, 230, 240) that extend outwardly from the blade body, the cutting teeth formed to have cutting edges (82, 140, 194) so that as the blade is reciprocated, the cutting teeth scrape away tissue against which the cutting teeth are pressed,

characterized in that:

at least one stop tooth (86, 146, 198, 234) also extends outwardly from the blade body, the at least one stop tooth being located adjacent the cutting teeth that (78, 94, 136, 154 190, 202, 230, 240) and having an outwardly directed face (88) with a crest (90), wherein the crest of the

outwardly directed face of the at least one stop tooth is located inwardly of the cutting edge of an adjacent cutting tooth and the outwardly directed cutting tooth is shaped so that, when the at least one stop tooth is pressed against tissue, the at least one stop tooth limits the depth to which the adjacent cutting tooth can be pressed against tissue.

2. The saw blade (60, 120, 180, 220, 250, 294) of Claim 1, wherein the blade is formed with plural said stop teeth (86, 146, 198, 234) and each said stop tooth is located between two said cutting teeth (78, 94, 136, 154 190, 202, 230, 240)

3. The saw blade (220, 250) of Claims 1 or 2, wherein: the blade is formed so that two adjacent cutting teeth

(230a and 230b, 230b and 230c, 240a and 24b, 240b and 240c, 190a and 202a, 202a and 190b 202b and 190c and 190c and 202c) are located different distances from a common reference line on the blade body; and

said at least one stop tooth (234a, 234b, 234d, 234e, 198a 198b) are positioned so that the outwardly directed face of said tooth is located forward of the tooth located closest to the common reference line and rearward of the tooth located furthest from the common reference line.

4. The saw blade (60, 180, 220, 250, 294) of any one of Claims 1 to 3, wherein:

said blade body (64, 182) has a main section and a neck that with at least one face that is recessed inwardly relative to an adjacent face of the main section of the blade body; both the cutting teeth and the stop teeth extend

outwardly from the neck and at least the cutting teeth have a thickness greater that a thickness of the neck; and

said blade body is formed so that between said at least one stop tooth and the adjacent cutting tooth there is a notch (98, 206, 258) and the notch extends into the neck of the blade body.

5. The saw blade (60, 180, 220, 250, 294) of Claim 4, wherein said blade body is formed so each of the opposed faces of the neck (72) is recessed inwardly relative to the face of the main section of the blade body adjacent the neck.

6. The saw blade (250) of Claims 4 or 5, wherein said blade body is formed so that:

said at least one stop tooth (198b) is located between two said cutting teeth (202a and 190b, 202b and 190c) and a notch between said stop tooth and the cutting tooth on each side of the stop tooth (258) .

7. The saw blade (60, 180, 220, 250, 294) of any one of Claims 1 to 6, wherein: there are plural pairs of adjacent cutting teeth and between each pair of adjacent cutting teeth there is at least said stop tooth so that said blade includes plural said stop teeth.

8. The saw blade (120) of any one of Claims 1 to 6, wherein :

plural said stop teeth (146) extend from the blade body; and

there are plural pairs of adjacent cutting teeth (136, 154) and wherein between at least one pair of adjacent cutting teeth, there is no stop tooth.

9. The saw blade (60, 120, 180, 220, 250, 294) of any one of Claims 1 to 8, wherein the at least one stop tooth (86, 146, 198, 234) is formed so a section (88) of said tooth that defines the crest (90) is curved.

10. The saw blade (60, 120, 180, 220, 250, 294) of any one of Claims 1 to 9, wherein: said cutting teeth are formed with rake surfaces (80, 138, 192) that scrape away tissue against which the cutting teeth are depressed when the blade is reciprocated; and said blade has a first set of cutting teeth (78, 136, 190, 230) with cutting edges that are oriented to so that, when the blade is reciprocated in a first direction, the first set of cutting teeth scrape away tissue and, when the blade is reciprocated in a second direction opposite the first direction, the first set of cutting teeth do not appreciably scrape away tissue and a second set of cutting teeth (94, 154, 202, 240) with cutting edges that are orientated so that when the blade is reciprocated in the first direction, the second set of cutting teeth scrape away tissue and, when the blade is reciprocated in the second the second set of cutting teeth scrape away tissue.

11. The saw blade (60, 180, 220, 250, 294) of Claim 10, wherein :

at least one pair of adjacent cutting teeth (78 and 94, 190b and 202b, 230c and 240a) comprises one tooth from the first set of teeth and one tooth from the second set of teeth; and

said at least one stop tooth (86, 198c, 234c) is located between the adjacent cutting teeth that comprises the tooth from the first set of teeth and the tooth from the second set of teeth.

12. The saw blade (60, 120, 180, 220, 250, 294) of any one of Claims 1 to 11, wherein:

the cutting teeth (78, 94, 136, 154 190, 202, 230, 240) and said at least one stop tooth (86, 146, 198, 234) extend forward from the distal end of the blade body (64, 124, 182) ; said features for (62, 66, 68, 122) holding the blade to a mount capable of pivoting the blade body back and forth around an axis that extends through a plane of the blade body.

13. The saw blade (294) of any one of Claims 1 to 12, wherein said blade is part of cartridge (270) that includes a static bar (272, 276) to which said blade is moveably mounted.