Abstract:
A saw blade assembly for use with a driver having an oscillatory drive member comprises an elongate sheath and an elongate monolithic blade. The sheath&#39;s proximal end is removably mountable on the driver. The sheath has an open interior which receives the blade. The blade&#39;s proximal end is pivotably mounted to the sheath&#39;s proximal end. The blade&#39;s distal cutting end extends out of the sheath&#39;s distal end and is transverse to the blade&#39;s central longitudinal axis. When cutting bone, the drive member pivots the blade&#39;s cutting end back and forth in an arc about a pivot point at the blade&#39;s proximal end while the driver holds the sheath stationary to protect surrounding tissues from the motions of the remainder of the blade. The long pivot radius between the proximal pivot point and the distal cutting end contributes to minimizing the angle of engagement of the cutting end to the bone.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The following invention relates generally to instruments for cutting bone during surgery. More particularly, the instant invention is directed toward surgical saw blades adapted to be operatively coupled to powered surgical instruments. 
     2. Description of the Prior Art 
     Powered oscillating surgical saws with coupled bone cutting surgical saw blades are widely used in orthopedic surgery. Surgeons have long faced the problem of reaching narrow and deep recesses with power-driven surgical saw blades. During surgery, the protection of soft tissue such as tendons, ligaments, muscles, vascular and neurological structures is crucial. As such, various power transmission mechanisms, which transmit power from the proximally (near the surgeon or user) disposed powered oscillating surgical saw to the distal (far end) cutting edge of the surgical saw blade, have been designed to limit the midline oscillatory excursion of the distal cutting edge, i.e., limit the cutting action of the distal cutting edge, thereby reducing the exposure of adjacent soft tissue structures to the high-speed oscillatory excursion of the surgical saw blade. 
     Such known power transmission mechanisms can include translation mechanisms, for example, the translation mechanisms described in U.S. Pat. Nos. 1,179,910, 2,854,981 and 7,497,860. Translation mechanisms typically include moving internal parts which transmit motion from an attached powered oscillating surgical saw to a distal pivoting cutting edge. For example, as shown in  FIG. 1A , a known surgical saw blade assembly  110  may include a plurality of linked gears  113 . A connected powered oscillating surgical saw can rotate the proximal most gear  113   a  in a small arc  115 . The resulting motion is transmitted through the plurality of linked gears  113 , causing distal cutting member  116  to oscillate about a distally disposed center of oscillation or pivot point  118  and moving the distal toothed cutting edge  117  in a small arc  119 . The pivot radius  122  of the distal cutting member  116  extends from the distally disposed center of oscillation  118  to the distal tips of the teeth of distal toothed cutting edge  117 . Another example is shown in  FIG. 1B , which shows a known surgical saw blade assembly  160  which comprises a pair of push rods  163   a  and  163   b . To move the distal cutting edge  169  in a small arc  171 , the first push rod  163   a  is driven in one direction, for example, as indicated by arrow  165   a , while the second push rod  163   b  is driven in the opposite direction, for example, as indicated by arrow  165   b . This reciprocating action of the push rods  163   a ,  163   b  causes the distal toothed cutting member  167  to oscillate about a distally disposed center of oscillation or pivot point  168 . The pivot radius  172  of the distal toothed cutting member extends from the distally disposed center of oscillation  168  to the distal tips of the cutting edge  169 . 
     These translation mechanisms are not without their disadvantages. With every additional moving component within a translation mechanism, there typically needs to be adequate dimensional clearance provided between the moving internal parts to allow them to move. By providing for such required freedom of motion, efficiency can be lost in such translation mechanisms. Furthermore, surgical saw blades typically operate at about 10,000 cycles per minute. Thus, much friction between the moving internal parts can be created when the surgical saw blade is in use. As such, efficiency can further be lost between the power source and the cutting edge of the surgical saw blade with a translation mechanism. 
     Additionally, these translation mechanisms often require their cutting edges to pivot from a distally disposed pivot point, for example pivot points  118  and  168  as shown in  FIGS. 1A and 1B , respectively. As a result, the teeth of the cutting edges engage bone at a very sharp and unstable angle. This sharp, unstable engagement angle can cause the surgical saw blade to buck and “kick”, i.e., become caught upon the bone being cut by the point of a tooth. This tendency of the surgical saw blade to buck and “kick” will typically reduce the overall cutting efficiency and accuracy of the saw blade assembly. The instability of the surgical saw blade can also translate back to the surgeon&#39;s hand, increasing the risk of an inaccurate bone cut. In at least some cases, the surgeon may be able to rein in the instability by maintaining a tighter grip on the proximally disposed powered oscillating surgical saw. However, maintaining a tighter grip increases the fatigue of the surgeon and the instability can manifest itself as torsional stresses placed upon the moving parts of the saw blade assembly. 
     In the specific cases of translation mechanisms incorporating reciprocating push rods, for example, the translation mechanisms shown in  FIG. 1B  and those described in U.S. Pat. Nos. 2,854,981 and 7,497,860, such torsional stresses may cause binding of the long push rods against the stationary components of the saw blade assembly. With the saw blade assembly operating at high speeds, for example, approximately 10,000 to 14,000 cycles per minute, such binding can cause additional friction between the push rods and the stationary elements of the saw blade assembly. This additional friction creates heat and can cause the moving portions of the saw blade assembly to slow down, further reducing the cutting efficiency of the cutting edge. If such binding starts to occur, a surgeon may mistake the resulting increased resistance as cutting resistance from the bone and push harder on the saw blade. Pushing harder on the saw blade assembly increases the very undesirable possibility of the saw blade skiving upwardly, which causes an inaccurate bone cut. Worse yet, the saw blade may dive deeper into the bone, well beyond the intended bone resection level. 
     Thus, known bone cutting surgical saw blades incorporating such translation mechanisms may not be ideal for efficiently and stably engaging and cutting bone at high speeds. Due to their multitude of moving internal parts, they can be mechanically inefficient. These known surgical saw blades can further be hampered by increased frictional forces caused by torsional stresses placed upon the saw blade assembly. 
     Other surgical saw blades without complicated translation mechanisms are also well known. These saw blades are described, for example, in co-assigned U.S. Pat. Nos. 6,022,353, 6,503,253, 6,723,101, and 7,527,628, the entire contents of which are incorporated by reference herein. Such saw blades are well-accepted in the orthopedic industry as having optimal bone cutting operational efficiency and simplicity in their unitary construction. However, these saw blades leave room for improvement in their ability to protect adjacent soft tissue from exposure to the cutting action of the blades. 
     As such, there is a need for improved surgical saw blades which engage and cut bone in a smooth, stable, and efficient manner, while protecting the adjacent soft tissue from exposure to the cutting action of the saw blade. 
     Other references of interest may also include: U.S. Publication Nos. 2009/0093815 and 2009/0093814, the Applications of which are co-assigned and fully incorporated herein by reference; U.S. Publication Nos. 2008/0243125 and 2008/0027449; and U.S. Pat. Nos. 5,839,196, 5,439,472, 5,382,249, 4,768,504, 4,617,930, and 1,726,241. U.S. Design patent Ser. No. 29/335,690, the contents of which are fully incorporated herein by reference, may also be of interest. 
     BRIEF SUMMARY OF THE INVENTION 
     Embodiments of the invention provide saw blade assemblies and systems using such saw blade assemblies which achieve safer, smoother, more reliable, more stable, and more efficient bone cutting. An exemplary saw blade assembly comprises an elongate monolithic blade, i.e., the elongate blade has a unitary construction with no moveably connected parts. The unitary construction of the elongate blade makes the saw blade assembly mechanically efficient. The elongate monolithic blade can be coupled to an oscillating drive member of a coupled drive unit and comprises proximal and distal ends. The elongate monolithic blade is driven in a small arc by the oscillating drive member from a center of oscillation or pivot point, at the proximal end. The distal end comprises a cutting edge which is shaped to engage or impact bone, or any target object, at a very shallow angle, reducing the occurrence of any disadvantageous bucking or “kicking.” The saw blade assembly further comprises a sheath coupled to and partially enclosing the elongate monolithic blade. In use, the sheath is held stationary to protect adjacent soft tissue from exposure to the cutting action of the elongate blade while the elongate monolithic blade is driven. 
     In a first aspect, embodiments of the invention provide a saw blade assembly for use with a driver having an oscillatory drive member. The provided saw blade assembly can perform surgical cuts to bone tissue with minimal injury to surrounding tissue. The saw blade assembly comprises an elongate sheath and an elongate monolithic blade. The elongate sheath has a proximal end, a distal end, and an open interior. The proximal end of the elongate sheath is removably mountable on the driver to be held stationary relative to the driver when the saw blade assembly performs surgical cuts. The elongate monolithic blade is received within the open interior of the sheath. The monolithic blade has a central longitudinal axis, a proximal end, and a distal cutting end. The proximal end is pivotably mounted to the proximal end of the elongate sheath and removably couples to the oscillatory drive member of the driver when the proximal end of the elongate sheath is mounted on the driver. The distal cutting end is transverse to the central longitudinal axis and extends from the distal end of the sheath. To perform surgical cuts, the oscillatory drive shaft pivots the distal cutting end back and forth about a center of oscillation at the proximal end of the monolithic blade when the proximal end of the monolithic blade is coupled to the oscillatory drive member. 
     In many embodiments, the distal cutting end is configured to engage bone tissue at an angle of less than about 10 degrees. This angle may be less than about 6 degrees or even less than about 3 degrees. 
     In many embodiments, the saw blade assembly further comprises at least one elongate support rib. The at least one elongate support rib may be coupled to the elongate sheath or may be formed in the elongate sheath. 
     The distal cutting end of the monolithic blade is typically perpendicular to the central longitudinal axis of the monolithic blade. 
     The distal cutting end of the monolithic blade will typically comprise a plurality of teeth. Each tooth comprises a distal tip. The tips of each tooth may be positioned on a single straight line perpendicular to the central longitudinal axis of the elongate monolithic blade. Each tooth may be identically shaped. The plurality of teeth may comprise an even number of teeth. 
     In some embodiments, each tooth is shaped as a right triangle. Each tooth has a right angle, a hypotenuse opposite the right angle, and a longitudinal side adjacent the hypotenuse. The right angle of each tooth is oriented at least one of toward or away from the central longitudinal axis of the blade. The longitudinal side of each tooth may be disposed along a radial line extending from the tip of the tooth to the center of oscillation at the distal end of the monolithic blade. The longitudinal sides of each tooth may be parallel with one another. The right angle of each tooth may oriented away from the central longitudinal axis of the monolithic blade. The distal cutting end may further comprise a centrally positioned tooth shaped as an isosceles triangle. The centrally positioned tooth may be formed by two right triangular teeth sharing the same longitudinal side disposed along the central longitudinal axis of the blade. 
     In some embodiments, the tips of the plurality of teeth are disposed along an arc centered about the center of oscillation at the proximal end of the monolithic blade. In some embodiments, each tooth is identically shaped as an approximately isosceles triangle and the tips of the teeth are disposed along a lateral line perpendicular to the central longitudinal axis of the monolithic blade. 
     In some embodiments, the plurality of teeth comprises a plurality of inner teeth and a plurality of outer teeth. The tips of the inner teeth may be disposed on a first single straight line perpendicular to the central longitudinal axis. The tips of the outer teeth may be disposed on a second single straight line perpendicular to the central longitudinal axis, the first single straight line being different than the second single straight line. 
     In many embodiments, at least a portion of the monolithic blade comprises at least one of metal, stainless steel, composite, carbon fiber composite, polymer, titanium, or ceramic. 
     Embodiments of the invention also provide a surgical saw system for performing surgical cuts to bone tissue with minimal injury to surrounding tissue. The surgical saw system comprises the above described saw blade assembly and a driver assembly. The drive assembly comprises the driver having the oscillatory drive member. The drive assembly is configured to couple to the saw blade assembly to pivotably drive the monolithic blade of the saw blade assembly to cut tissue. 
     In many embodiments, the surgical saw system further comprises an external battery pack coupleable to the drive assembly to power the drive assembly. 
     In many embodiments, the drive assembly is hand-holdable. 
     In many embodiments, the drive assembly comprises a locking mechanism having an open configuration and a closed configuration. The saw blade assembly is insertable into the locking mechanism in the open configuration to couple the saw blade assembly to the drive assembly. The locking mechanism in the closed configuration holds the sheath of the saw blade assembly stationary relative to the driver and couples to the elongate monolithic blade when the drive assembly is coupled to the saw blade assembly. The locking mechanism may comprise a lever actuatable to switch the locking mechanism between the open and closed configurations. The near end of the monolithic blade may define an aperture at the center of oscillation The linkage mechanism may comprise a knob which fits into the aperture of the near end of the monolithic blade when the linkage mechanism is in the closed configuration when the drive assembly is coupled to the saw blade assembly. The locking mechanism may comprise a sleeve slot adapted to hold the near end of the sleeve stationary relative to the driver when the saw blade assembly is inserted into the locking mechanism. 
     In many embodiments, the oscillatory drive member comprises a blade slot adapted to hold the near end of the monolithic blade when the saw blade assembly is inserted into the locking mechanism. 
     In many embodiments, the drive assembly comprises an electric motor and an eccentric mechanism coupled to the electric motor. The eccentric mechanism may be coupled to the oscillatory drive member to oscillate the blade about its center of oscillation when the saw blade assembly is coupled to the drive assembly. The drive assembly may further comprise a trigger pressable to activate the electric motor. The electric motor may be removable from the drive assembly. 
     In many embodiments, the surgical saw system further comprises a noise absorbent sheath for covering at least a portion of the drive assembly. 
     In many embodiments the surgical saw system further comprises at least one cutting guide configured to guide the saw blade assembly in cutting bone tissue. 
     Embodiments of the invention also provide a method for performing surgical cuts to bone tissue with minimal injury to surrounding tissue. The saw blade assembly as described above is provided. The saw blade assembly is engaged with the oscillatory drive member. The saw blade assembly is positioned at a target site. To cut tissue at the target site with the far cutting end of the monolithic blade of the saw blade assembly, movement that is atraumatic to surrounding tissue is produced. 
     To engage the saw blade assembly with the oscillatory drive member, the near end of the monolithic blade may be inserted into a blade slot of the oscillatory drive member. When the saw blade assembly is engaged with the oscillator drive member, the near end of the sheath of the saw blade assembly may be held stationary with a locking mechanism of the driver. To cut tissue at the target site, the blade of the saw blade assembly may be pivoted back and forth about the center of oscillation at the near end of the blade. The movement of the cutting surface may be constrained within one plane. The tissue site may be an orthopedic site, a bone, a vertebrae or a skull. The distal cutting end of the blade may be positioned within a tissue structure while movement of the remainder of the blade member does not cause hemorrhage of a vascular network of the structure. 
     The method may further comprise the utilization of a channel in at least a portion of the saw blade assembly to view, aspirate or irrigate the tissue site. 
     In another aspect, embodiments of the invention provide a method for surgical cutting of bone. The bone is contacted with a distal cutting edge of an elongate monolithic blade. The distal end comprises a plurality of teeth. Each tooth ends in a distal tip. The distal tips of the teeth are positioned on a line perpendicular to the central longitudinal axis of the elongate monolithic blade such that said teeth provide better tracking of the elongate monolithic blade when forming a kerf in the bone. The bone is cut by oscillating the distal cutting edge in a small arc about a center of oscillation at a proximal end of the elongate monolithic blade to form the kerf. The tissue surrounding the bone is shielded from the movement of the portion of the elongate monolithic blade proximal to the distal cutting end with an elongate sheath enclosing said portion of the elongate monolithic blade. The teeth can cut both progressively and sequentially as the kerf begins to form into a v-shape to provide stable, accurate, aggressive cutting and efficient chip removal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a known surgical saw blade assembly having a plurality of linked gears; 
         FIG. 1B  shows a known surgical saw blade assembly having a pair of reciprocating push rods; 
         FIG. 2A  shows a front view of a surgical saw blade assembly according to embodiments of the invention; 
         FIG. 2B  shows a side view of the surgical saw blade assembly of  FIG. 2A ; 
         FIG. 2C  shows a front view of the surgical saw blade assembly of  FIG. 2A  with its distal cutting end pivoted to the right; 
         FIG. 2D  shows a front view of the surgical saw blade assembly of  FIG. 2A  with its distal cutting end pivoted to the left; 
         FIG. 3A  shows the known surgical saw blade assembly of  FIG. 1B  engaging bone; 
         FIG. 3B  shows the known surgical saw blade assembly of  FIG. 2A  engaging bone; 
         FIG. 4A  shows a perspective view of the surgical saw blade assembly of  FIG. 2A ; 
         FIG. 4B  shows an exploded view of the surgical saw blade assembly of  FIG. 2A ; 
         FIG. 4C  shows an exploded view of a surgical saw blade assembly according to an embodiment of the invention; 
         FIG. 4D  shows an exploded view of a surgical saw blade assembly according to another embodiment of the invention; 
         FIG. 4E  shows an exploded view of a surgical saw blade assembly according to yet another embodiment of the invention; 
         FIGS. 5A to 5H  show distal cutting edges of surgical saw blade assemblies according to embodiments of the invention; 
       FIG.  5 I 1  shows a front view of an elongate blade of a surgical saw blade assembly according to embodiments of the invention; 
       FIG.  5 I 2  shows a magnified view of the distal cutting edge of FIG.  5 I 1 ; 
         FIG. 5J  shows an elongate blade of a surgical saw blade assembly according to embodiments of the invention; 
         FIGS. 6A to 6U  show a distal cutting edge engaging and cutting bone according to embodiments of the invention; 
         FIG. 7  shows a perspective view of a surgical saw blade system according to embodiments of the invention, including the surgical saw blade assembly of  FIG. 2A  and a hand holdable drive unit; 
         FIG. 7A  shows an exploded view of the hand holdable drive unit of  FIG. 7 ; 
         FIG. 7B  shows a perspective view of a surgical saw blade system according to embodiments of the invention, including the surgical saw blade assembly of  FIG. 2A  and a hand holdable drive unit with a removable electric motor; 
         FIG. 8A  shows a perspective view of the surgical saw blade assembly of  FIG. 2A  and the hand holdable drive unit of  FIG. 7  in its unlocked configuration; 
         FIG. 8B  is a magnified view of the locking mechanism of the hand holdable drive unit of  FIG. 8A ; 
         FIG. 9A  shows a perspective view of the surgical saw blade assembly of  FIG. 2A  and the hand holdable drive unit of  FIG. 7  in its locked configuration; 
         FIG. 9B  is a magnified view of the locking mechanism of the hand holdable drive unit of  FIG. 8A ; and 
         FIG. 10  shows a surgical saw blade kit according to embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 2A and 2B  respectively show front and side views of a saw blade assembly  201  according to embodiments of the invention. The saw blade assembly  201  comprises an elongate monolithic blade  203  and an elongate sheath  204 . The elongate monolithic blade  203  has a unitary construction with no moveably connected parts, making it much more mechanically efficient than known surgical saw blades employing translation mechanisms with moveably connected moving internal parts. Typically, the majority of the elongate monolithic blade  203  is housed within the interior of the elongate sheath  204 . The elongate sheath  204  will typically have no other moving internal parts besides the elongate monolithic blade  203 . The elongate monolithic blade  203  has a proximal end  203   a  and a distal cutting end  203   b  comprising a cutting edge  205  which typically comprises a plurality of sharp projections or teeth. The elongate sheath  204  has a proximal end  204   a  and a distal end  204   b , which as shown in  FIGS. 2A and 2B , may be U-shaped. The elongate sheath  204  further defines an aperture  207  from where the proximal end  203   a  of the elongate monolithic blade  203  extends through. As shown in  FIGS. 2C and 2D , when coupled to and driven by a drive source at the proximal end  203   a , the elongate monolithic blade  203  oscillates in a small arc  208  about a center of oscillation or pivot point  202  at the proximal end  203   a . The distal cutting end  203   a  of the elongate monolithic blade  203  extends out of the distal end  204   b  of the elongate sheath  204  to cut tissue. Because the remainder of the body of the elongate monolithic blade  203  is enveloped by the elongate sheath  204 , tissue is only exposed to the high-speed lateral motion of the distal cutting end  203   b.    
     In some embodiments, the saw blade assembly  201  may be lubricated to reduce friction. A lubricous material or coating may be provided for the elongate monolithic blade  203  and/or the elongate sheath  204 . For example, the exterior surface of the elongate monolithic blade  203  and/or at least the internal surface of the elongate sheath  204  may be coated with a lubricous substance, for example; composite diamond, thermal plasma sprayed ceramic, zirconia nitride, titanium-carbo nitride, titanium nitride, titanium oxide, chromium oxide, or the surfaces of the monolithic blade  203  and/or the elongate sheath  204  may be subject to plasma or ion nitriding, inducing a lubricious conversion layer upon them. 
     In some embodiments, the elongate sheath  204  comprises at least one elongate support member  206 . As shown in  FIG. 2A , the elongate sheath  204  comprises four elongate support member  206 , two for each side of the elongate sheath  204 , the two comprising one long support member and one short support member. An elongate support member  206  may comprise an external member or bar attached to the elongate sheath  204 , for example, by welding. An elongate support member  206  may be formed in the elongate sheath  204 , for example, as an indented region. In many embodiments, the saw blade assembly  201  can be longitudinally flexed and bent, as indicated by arrows  211   a  and  221   b , without significantly or adversely affecting the oscillating cutting motion of the elongate monolithic blade  203 . 
     As shown in  FIGS. 2A and 2B , the cutting edge  205  is disposed at the distal most portion of the distal cutting end  203   b . The cutting edge  205  may alternatively be placed at other locations along the distal cutting end  203   b . The cutting edge  205  typically comprises a plurality of sharp projections or teeth but may alternatively comprise a single sharp edge or a combination of an edge or teeth (e.g., similar to a serrated knife). The teeth of the cutting edge  205  can be hardened relative to the remainder of the elongate monolithic blade  203  to improve their ability to cut bone. Also, the hardness, pitch and dimensions of the teeth can be selected for the particular bone tissue to be cut, for example, femoral, tibial, hip, spinal, cranial, dental mandibular, and/or other bone tissue. Smaller teeth and pitch can be used for finer cuts in, for example, spinal tissue, whereas larger teeth and pitch can be used for cuts to the distal or proximal femur or tibia. For example, the teeth may have a finer pitch in the central portion of the blade and a coarser pitch along the edges of the blade. 
     The saw blade assembly  201 , including elongate monolithic blade  203  and the elongate sheath  204 , can be fabricated from a number of or a matrix of surgical grade metals, alloys, ceramics, cera-metallic composites or other composites known in the art. Preferably, at least the distal cutting end  203   b  of the elongate monolithic blade  203  comprises surgical grade stainless steel, for example, hardened and tempered stainless steel. Forging, machining, laser cutting, stamping, grinding, and/or other known metal fabrication methods may be used to fabricate an elongate monolithic blade  203  and an elongate sheath  204  comprising metal. The elongate monolithic blade  203  and/or the elongate sheath  204  can also be treated or processed using one or more known metal treatment methods. The specific material for the elongate monolithic blade  203  and the elongate sheath can be selected based on one or more properties including elastic modulus, elastic limit, tensile strength, yield strength, compressive strength, resonance frequencies, lubricity, coefficient of friction, and hardness. 
     In some embodiments, the saw blade assembly may be manufactured so that different portions of the saw blade assembly have different material properties. For example, the distal and proximal portions of the saw blade assembly can be fabricated from harder materials while the middle portion of the saw blade assembly can be fabricated from more flexible materials. This may allow the saw blade assembly to better bend and flex longitudinally while maintaining the material property requirements of the cutting edge  205 . Alternatively or in combination, different portions of the saw blade assembly may be treated using different known metallurgical treatments such as annealing, tempering, nitriding, stress relieving, work hardening, and surface treatment and/or coating. 
       FIG. 2C  again shows a front view of the surgical saw blade assembly  201 , this time with the distal cutting end  203   b  pivoted toward to its right-most lateral position.  FIG. 2D  shows a front view of the surgical saw blade assembly with the distal cutting end  203   b  pivoted toward its left-most lateral position. The elongate monolithic blade  203  defines a central longitudinal axis as shown by dotted line  208 . The central longitudinal axis  208  separates the elongate monolithic blade  203  into two lateral sides. Typically, the central longitudinal axis  208  extends from the center of oscillation  202  to the middle of the cutting edge  205 . As previously discussed, when coupled to and driven by a drive source at the proximal end  203   a , the elongate monolithic blade  203  oscillates in a small arc  208  about a center of oscillation or pivot point  202  at the proximal end  203   a . The pivot radius  209  of the elongate monolithic blade  203  thus extends from the proximally disposed center of oscillation  202  to the distal tips of the teeth of the cutting edge  205 . Thus, the pivot radius  209  of the elongate monolithic blade  203  is much longer than those of known surgical saw assemblies, for example, the pivot radius  122  of known saw blade assembly  110  shown in  FIG. 1A  and the pivot radius  172  of known saw blade assembly  160  shown in  FIG. 1B . Because the pivot radius  209  is much longer, the cutting edge  205  engages or impacts bone or any target object at an angle much shallower than that of known saw blade assemblies which instead have distally disposed centers of oscillation. This is shown by  FIGS. 3A and 3B  which shows the impact angles of the known saw blade assembly  160  and the saw blade assembly  201 , respectively. As shown in  FIG. 3A , because of the shorter pivot radius  172 , the distal toothed cutting member  167  impacts bone B at a sharp angle  301 , for example, an angle of about 13.5 degrees or greater, as it oscillates. As shown in  FIG. 3B , because of the longer pivot radius  209 , the distal cutting end  203   b  impacts bone B at a shallower angle  302  as it oscillates. The elongate monolithic blade  203  will typically be configured so that the shallow angle  302  comprises an angle of less than about 10 degrees, preferably an angle of less than about 6 degrees, and more preferably an angle of less than about 3 degrees. 
       FIG. 4A  shows a perspective view of the surgical saw blade assembly  201 .  FIG. 4B  shows an exploded view of the surgical saw blade assembly of  201 . The elongate sheath  204  comprises a first elongate sleeve portion  204   c , which may be a top portion, and a second elongate sleeve portion  204   d , which may be a bottom portion. The aperture  207  is present on both the first elongate sleeve portion  204   c  and the second elongate sleeve portion  204   d . A spacer  211  may be disposed between the first elongate sleeve portion  204   c  and the second elongate sleeve portion  204   d  at their proximal ends. The elongate monolithic blade  203  may comprise a main blade body  213  and a drive unit coupling member  212  fixedly coupled to a main body  213 . At least a portion of the drive unit coupling member  212  will be thicker than and/or have an area greater than that of the aperture  207 . Thus, when the first elongate sleeve portion  204   c , the main blade body  213 , the spacer  211 , the second elongate sleeve portion  204   d , and the drive unit coupling member  212  are brought together and attached to form the surgical saw blade assembly  201 , the main blade body  213  is prevented from sliding out of the elongate sheath  204  and is also pivotable within the elongate sheath  204 , even without attachment to a drive unit. In some embodiments, the drive unit coupling member  212  is integral with the main body  213 , and the elongate sheath  204  comprises more than two elongate sleeve portions which are built around the elongate monolithic blade  203 . 
     The surgical saw blade assembly  201  may further comprise elongate support members  206 . The first elongate sleeve portion  204   c  and the second elongate sleeve portion  204   d  may have complimentary support members  206 . The support members  206  may comprise an external member or bar attached to at least one of the first elongate sleeve portion  204   c  or the second elongate sleeve portion  204   d , for example by welding. Alternatively or in combination, the support members  206  may be formed by indentations in the respective sleeve portions. Complimentary support members  206  may be lap-welded or spot-welded together to make the elongate sheath  204  more structurally rigid. 
     In some embodiments, for example, as shown in  FIG. 4C , the main body  213  may have a central aperture  230 . Having a central aperture  230  can, among other things, lighten the main body  213  as well as provide clearance for a centrally disposed elongate support member  206 . The centrally disposed elongate support member  206  may comprise an internal bar attached to at least one of the first elongate sleeve portion  204   c  or the second elongate sleeve portion  204   d , for example, by welding. 
     Alternatively or in combination, the support members  206  may comprise complimentary first elongate sleeve portion indentations  206   c  and second elongate sleeve portion indentations  206   d , for example, as shown in  FIG. 4D . Complimentary indentations  206   c ,  206   d  may be attached together, for example, by welding, lap-welding, spot-welding, brazing, soldering, etc., to make the elongate sheath  204  more structurally rigid. As shown in  FIG. 4D , there may be more than one centrally disposed elongate support member  206  and the main body  213  of the elongate monolithic blade  203  may have more than one central aperture  230 , each central aperture  230  corresponding to and straddling their respective centrally disposed support member  206 . 
     Alternatively or in combination, the surgical saw blade assembly  201  may comprise a plurality of discrete support members  206   e  which are attached to the first elongate sleeve portion  204   c  and the second elongate sleeve portion  204   d , for example, as shown in  FIG. 4D . The discrete support members  206   e  may be attached together, for example, by welding, spot-welding, brazing, soldering, etc., to make the elongate sheath  204  more structurally rigid. As shown in  FIG. 4E , there may be more than one centrally disposed elongate support member  206   e  and the main body  213  of the elongate monolithic blade  203  may have more than one central aperture  230 , each central aperture  230  corresponding to and straddling their respective centrally disposed support member  206 . 
     The distal cutting end  203   b  of the elongate monolithic blade  203  can have many configurations.  FIGS. 5A to 5H  show exemplary distal cutting ends  203   b.    
     In many embodiments, the cutting edge  205  may be similar to the cutting edges described in co-assigned U.S. Pat. Nos. 6,022,353, 6,503,253, 6,723,101, and 7,527,628 and U.S. Publication Nos. 2009/0093815, 2009/0093814. 
     The cutting edge  205  can comprise a plurality of teeth. Different toothed cutting edges  205  can have different numbers of teeth. For example, as shown in  FIGS. 2A ,  2 C,  3 B,  4 A,  4 B and  5 A, the cutting edge  205   a  can have a total of eight teeth, with four teeth on each side of the central longitudinal axis  209  of elongate monolithic blade  203 . As shown in  FIG. 5B , the cutting edge  205   b  can have a total of six teeth, with three teeth on each side of central longitudinal axis  209  of elongate monolithic blade  203 . As shown in  FIG. 5C , the cutting edge  205   c  can have a total of twelve teeth, with six teeth on each side of central longitudinal axis  209  of elongate monolithic blade  203 . As shown in  FIG. 5D , the cutting edge  205   d  can have a total of ten teeth, with five teeth on each side of central longitudinal axis  209  of elongate monolithic blade  203 . Also as shown in  FIG. 5D , the proximal edges  216  of the distal cutting end  203   b  can be angled. As shown in  FIG. 5E , the cutting edge  205   e  can have a total of sixteen eight teeth, with eight teeth on each side of central longitudinal axis  209  of elongate monolithic blade  203  and with pairs of teeth flaring from a common central member, forming the shape of a “whale tale.” As shown in  FIG. 5F , the cutting edge  205   f  can have a total of twelve teeth, with six teeth on each side of central longitudinal axis  209  of elongate monolithic blade  203 , each tooth being shaped as an isosceles triangle. As shown in  FIG. 5G , the cutting edge  205   g  can have a total of six teeth, with three teeth on each side of central longitudinal axis  209  of elongate monolithic blade  203  and a central void. As shown in  FIG. 5H , the cutting edge  205   h  can have a total of seven teeth, with three teeth on each side of central longitudinal axis  209  of elongate monolithic blade  203  and one central tooth. Any number and/or arrangement of teeth may be used. The distal cutting ends  203   b  have varying levels of width, depending on the requirement of a surgeon or of a specific procedure. 
     In some embodiments, for example, as shown in  FIG. 5F , the tips of the teeth form an arc  515  coinciding with the arc of travel of the blade. More preferably, however, many embodiments of the invention have the tips of the teeth forming a single straight line  510 , for example, as shown in  FIGS. 5A ,  5 B,  5 C,  5 D,  5 E,  5 G and  5 H, i.e., the teeth are arranged in a “flat-top” pattern. Preferably, the straight line  510  is perpendicular to the central longitudinal axis  209  of the elongate monolithic blade. Having the teeth arranged in a “flat-top” pattern causes each tooth to progressively cut more material than the previous tooth as explained in more detail below. Collectively, all teeth contact the bone to be cut make progressive contributions. As the distal cutting end having its teeth in a “flat-top” pattern delves more deeply into the bone, the teeth on one end of the cutting edge may contact bone while the teeth on the opposite end are pulled away from the bone, making bone chip evacuation much more efficient and reducing friction and thus the operating temperature of the distal cutting end. Having the teeth in a “flat-top” pattern also contributes to the shallow impact angle of the distal cutting end  203   b  as explained in detail below. Cutting with teeth in a “flat-top” pattern forming a straight line  510  substantially perpendicular to the central longitudinal axis  209  of the elongate monolithic blade  203  generally results in a shallow convex or “v-shaped” kerf when engaging and cutting bone. When the distal cutting end having its teeth in an “arc” pattern delves more deeply into the bone, each of the teeth may contact bone tissue, increasing friction and thus the operating temperature of the distal cutting end and making bone chip evacuation much less efficient. Cutting teeth in an “arc” pattern generally results in a convex-shaped kerf being when engaging and cutting bone. 
     As shown in  FIGS. 5A ,  5 B,  5 C,  5 D,  5 G,  5 H,  5 I 1 , and  5 I 2 , the teeth of the cutting edge  205  (including cutting edge  205   a , cutting edge  205   b , cutting edge  205   c , cutting edge  205   d , cutting edge  205   e , cutting edge,  205   g , and cutting edge  205   h , and cutting edge  205   i ) can be shaped as right triangles. For example, FIG.  5 I 1  shows an elongate monolithic blade  203  having a cutting edge  205  with a total of twelve teeth, with six teeth on each side of central longitudinal axis  209  of elongate monolithic blade  203 . FIG.  5 I 2  shows a magnified view of the distal cutting end  203   b  and the cutting edge  205  of FIG.  5 I 1 . As shown, for example, by FIG.  5 I 2 , each tooth  220  has a free longitudinal side  245 , a right angle  240 , a hypotenuse  235  opposite the right angle  240 , and a distal tip  235 . The cutting occurs on the tip of the teeth. 
     As shown in  FIGS. 5A ,  5 B,  5 C,  5 D,  5 I 1 , and  5 I 2 , the teeth of the cutting edge  205  (including cutting edge  205   a , cutting edge  205   b , cutting edge  205   c , cutting edge  205   d , and cutting edge  205   i ) may be oriented so that their right angles and hypotenuses face toward the central longitudinal axis  209  of the elongate monolithic blade  203 . As shown in  FIGS. 5G and 5H , the teeth of the toothed cutting edge  205  (including cutting edge  205   g  and cutting edge  205   h ) may alternatively be oriented so that their right angles and hypotenuses face away from the central longitudinal axis  209  of the elongate monolithic blade  203 . In some embodiments, for example, as shown by  FIG. 5E , the teeth of the toothed cutting edge  205  may comprise some teeth that have their right angles and hypotenuses facing toward the central longitudinal axis  209  and other teeth that have their right angles and hypotenuses facing away from the central longitudinal axis  209 . In some embodiments, the right triangles of the teeth may be “near” right angles with the included angle greater than 90 degrees for a more aggressive cut. 
       FIG. 5J  shows an elongate monolithic blade  203  according to another embodiment of the invention. The distal cutting edge  205   j  of the elongate monolithic blade  203  comprises a plurality of teeth  220 . The distal cutting edge  205   j  has an odd number of teeth  220 , with a central isosceles shaped tooth. The central isosceles shaped tooth and its laterally adjacent teeth, which are shaped as right triangles with their hypotenuses facing toward the central longitudinal axis  209 , are positioned forward relative to the remainder of the teeth, which are shaped as right triangles with their hypotenuses facing toward the central longitudinal axis  209 . The tips of the remainder of the teeth, i.e., the outer teeth, are disposed on a line  505  perpendicular to the central elongate axis  209 . The tips of the central isosceles shaped tooth and its laterally adjacent teeth are disposed on a line  507  perpendicular to the central elongate axis  209  and forward of the line  505 . 
     Each of the triangular teeth of the distal cutting edge  205  may have approximately the same size and/or shape. In the distal cutting edge  205 , the central isosceles triangular tooth may comprise two right angled teeth sharing the same longitudinal side. In many embodiments, the triangular teeth of the distal cutting edge  205  may have a size and shape slightly different from one another. For example, in the embodiments of  FIGS. 5A ,  5 B,  5 C and  5 D, the longitudinal side of each tooth may coincide with their respective radial line  505  extending from the center of oscillation  202  to the distal tip of the same tooth. Likewise, in the embodiment of FIGS.  5 I 1  and  5 I 2 , the longitudinal side of each right triangular tooth may coincide with its respective radial line  505  extending from the center of oscillation  202  to the distal tip of the same tooth. Thus, the right angles  240  of each tooth face toward the central longitudinal axis  209  at slightly different angles, causing each tooth to have a slightly different size and shape from one another. The longitudinal sides of the teeth of the distal cutting edge  205  of  FIG. 5H  may also be similarly configured (that is, to have the longitudinal sides of each tooth coincide with each tooth&#39;s radial line  505 ) to have the right angles of each tooth face away from the central longitudinal axis  209  at slightly different angles. 
       FIGS. 6A to 6U  show the distal cutting edge  203   b  as it engages and cuts bone tissue B through a cycle of oscillation. In the embodiments of  FIGS. 6A to 6U , the distal cutting edge of the distal cutting end  203   b  comprises twelve teeth, with two pairs of six right triangular teeth disposed on opposite sides of the central longitudinal axis  209 . The distal teeth of twelve teeth are arranged to form a straight line perpendicular to the central longitudinal axis  209 . 
       FIG. 6A  shows the distal cutting edge  203   b  brought into contact with the bone B such that the distal cutting edge is tangent to the center part of the exterior of the bone B. The exterior of bone B, which may be, for example, a femur or a tibia, is typically rounded. Thus, only the left central tooth  220 A 1  and the right central tooth  220 B 1 . As the cycle of oscillation of the distal cutting edge  203   b  starts, the distal cutting edge  203   b  moves toward the right as indicated by right-facing arrow  60 . 
       FIG. 6B  shows the distal cutting edge  203   b  as it progresses through the cycle of oscillation from the time point shown in the previous figure,  FIG. 6A . As the distal cutting edge  203   b  moves to the right, the left central tooth  220 A 1  has begun to cut bone B, the left next to center tooth  220 A 2  contacts the exterior of the bone B, and the right central tooth  220 B 1  has begun to move away from the exterior of the bone B, giving more space for the bone chips cut by the left central tooth  220 A 1  to be brushed away. 
       FIG. 6C  shows the distal cutting edge  203   b  as it progresses through the cycle of oscillation from the time point shown in the previous figure,  FIG. 6B . As the distal cutting edge  203   b  continues to move to the right, the left central tooth  220 A 1  continues to cut bone B, the left next to center tooth  220 A 2  has begun to cut bone B, and the left next to next to center tooth  220 A 3  contacts the exterior of bone B. 
       FIG. 6D  shows the distal cutting edge  203   b  as it progresses through the cycle of oscillation from the time point shown in the previous figure,  FIG. 6C . As the distal cutting edge  203   b  continues to move to the right, the left center tooth  220 A 1  and the left next to center tooth  220 A 2  continue to cut bone B, the left next to next to center tooth  220 A 3  starts to cut bone B, and the left middle tooth  220 A 4  contacts the exterior of bone B. 
       FIG. 6E  shows the distal cutting edge  203   b  as it progresses through the cycle of oscillation from the time point shown in the previous figure,  FIG. 6D . As the distal cutting edge  203   b  continues to move to the right, the left center tooth  220 A 1 , the left next to center tooth  220 A 2 , and the left next to next to center tooth  220 A 4  continue to cut bone B and the left middle outer tooth  220 A 5  contacts the exterior of bone B. 
       FIG. 6F  shows the distal cutting edge  203   b  as it progresses through the cycle of oscillation from the time point shown in the previous figure,  FIG. 6E . As the distal cutting edge  203   b  continues to move to the right, the left center tooth  220 A 1 , the left next to center tooth  220 A 2 , the left next to next to center tooth  220 A 4 , and the left middle outer tooth  220 A 5  continue to cut bone B and the left outer tooth  220 A 6  contacts the exterior of bone B. 
       FIG. 6G  shows the distal cutting edge  203   b  as it progresses through the cycle of oscillation from the time point shown in the previous figure,  FIG. 6F . As the distal cutting edge  203   b  continues to move to the right, the left center tooth  220 A 1 , the left next to center tooth  220 A 2 , the left next to next to center tooth  220 A 4 , the left middle outer tooth  220 A 5 , and the left outer tooth  220 A 6  continue to cut bone B. 
       FIG. 6H  shows the distal cutting edge  203   b  as it progresses through the cycle of oscillation from the time point shown in the previous figure,  FIG. 6G . The distal cutting edge  203   b  having reached its right most position, reverses its course and begins to move to the left as indicated by left-facing arrow  61 . The distal cutting edge  203   b  may be advanced slightly toward the bone B as its direction reverses. The left center tooth  220 A 1 , the left next to center tooth  220 A 2 , the left next to next to center tooth  220 A 3 , the left middle tooth  220 A 4 , and the left middle outer tooth  220 A 5  continue to cut bone B but from the opposite direction. The left outer tooth  220 A 6  begins to move away from contacting the exterior of bone B, providing an evacuation window for bone chips, and begins to cool as it experiences less friction. The right center tooth  220 B 1  begins to contact the exterior of the bone B. 
       FIG. 6I  shows the cutting edge  203   b  as it progresses through the cycle of oscillation from the time point shown in the previous figure,  FIG. 6H . As the distal cutting edge  203   b  continues to move to the left, the left center tooth  220 A 1 , the left next to center tooth  220 A 2 , the left next to next to center tooth  220 A 3 , the left middle tooth  220 A 4 , and the left middle outer tooth  220 A 5  finish up cutting their respective portions of bone B. The right center tooth  220 B 1  begins to cut bone B and the right next to center tooth  220 B 2  begins to contact the exterior of bone B. 
       FIG. 6J  shows the cutting edge  203   b  as it progresses through the cycle of oscillation from the time point shown in the previous figure,  FIG. 6H . Each of the left teeth  220 A 1 ,  220 A 2 ,  220 A 3 ,  220 A 4 ,  220 A 5  and  220 A 6  have finished cutting their respective portions of bone B and have begun to or are already moved away from contacting the exterior of the bone B. As these teeth now experience less friction, they begin to cool. The right center tooth  220 B 1  and the right next to center tooth  220 B 2  continue to cut their respective portions of bone B. 
       FIGS. 6K to 6S  show the cutting edge  203   b  as it sequentially progresses through the cycle of oscillation from the time point shown in their respective previous figures. As the distal cutting edge  203   b  continues to move to the left, the right center tooth  220 B 1 , right next to center tooth  220 B 2 , the right next to next to center tooth  220 B 3 , the right middle tooth  220 B 4 , the right middle outer tooth  220 B 5 , and the right outer tooth  220 B 6  sequentially and progressively contact and cut the bone B similarly to the left teeth  220 A 1 ,  220 A 2 ,  220 A 3 ,  220 A 4 ,  220 A 5  and  220 A 6  previously described. The left teeth  220 A 1 ,  220 A 2 ,  220 A 3 ,  220 A 4 ,  220 A 5  and  220 A 6  progressively move away from the bone B, allowing these teeth to experience less friction and continue to cool. This also give additional space for the bone chips cut by right teeth  220 B 1 ,  220 B 2 ,  220 B 3 ,  220 B 4 ,  220 B 5  and  220 B 6  to be brushed away. 
       FIG. 6S  shows the cutting edge  203   b  as it reaches its left most position, completing one full cycle of oscillation. Thereafter, the cutting edge  203   b  reverses its course and moves toward the right. The cutting edge  203   b  may be slightly advanced toward the bone B as its direction changes. The right teeth  220 B 1 ,  220 B 2 ,  220 B 3 ,  220 B 4 ,  220 B 5  and  220 B 6  progressively cut in the opposite direction from before and then move away from the bone B. The left teeth  220 A 1 ,  220 A 2 ,  220 A 3 ,  220 A 4 ,  220 A 5  and  220 A 6  progressively contact and cut the bone B as described above. As each tooth cuts the bone B, its respective opposite tooth (for example, left outer tooth  220 A 6  is opposite right outer tooth  220 B 6 ) is finished cutting and is cooled and cleaned of chips. Cycles of oscillation continues until the cut desired by the surgeon is completed. 
       FIG. 6T  shows the cut or kerf on bone B.  FIG. 6U  shows a magnified view of the cut or kerf on bone B. The cutting edge  203   b  has been retracted to better show the cut or curf in  FIGS. 6T and 6U . The kerf has a staircase shape and is slightly V-shaped or convex. The kerf generally approximates the straight line of the distal tips of the teeth of the distal cutting edge  205 . In addition to the long pivot radius of the elongate monolithic blade  203 , the progressive cutting from the teeth of cutting edge  203   b  by the “flat-top” arrangement of these teeth result in the impact angle of the teeth and thus the angle  302  of the kerf being quite shallow. As angle  302  of the kerf is much shallower than that of those made by known surgical saws, it lends accuracy and stability to the surgical bone cutting performed by the surgeon. 
       FIG. 7  shows a surgical saw blade system  700  according to embodiments of the invention. The surgical saw blade system  700  includes the surgical saw blade assembly  201 , a hand holdable drive unit  710 , and a battery pack  750 .  FIG. 7A  shows an exploded view of the hand holdable drive unit  710 . The hand holdable drive unit  710  comprises an internal electric motor  711 , an internal eccentric mechanism  713 , circuitry  714 , a locking mechanism  715  (having a main body  716 , a lever  717 , and an internal oscillating member  719 ), a hand holdable portion  720 , a trigger  725 , and a battery interface at its bottom  730 . The battery pack  750  can be removeably coupled to the hand holdable drive unit  710  to power it. Typically, the hand holdable drive unit  710  and the battery pack  750  are configured so that the battery pack  750  slides into the bottom  730  of the hand holdable drive unit  710 . In some embodiments, for example as shown in  FIG. 7B , the internal electric motor  711  may be removable from the hand holdable drive unit  710  so that it can be easily removed, disposed, and replaced, for example, after a single use. Alternatively or in combination, the hand holdable drive unit  710  may be disposed after a single use while the removable electric motor  711  is provided as a reusable motor pack. 
     The surgical saw blade assembly  201  is removably coupleable with the hand holdable drive unit  710  through the locking mechanism  715 , which has an unlocked configuration in which the surgical saw blade assembly  201  can be inserted therein and a locked configuration which tightly holds the surgical saw blade assembly  201 . The lever  717  can be used to toggle the linkage mechanism  715  between the unlocked and locked configurations. In the locked configuration, the proximal end  203   b  of the elongate monolithic blade  203  is tightly mounted on the oscillating member  719 . When the surgical saw blade assembly  201  is coupled with the hand holdable drive unit  710 , pulling the trigger  725  causes the elongate monolithic blade  203  of the surgical saw blade assembly  201  to oscillate and cut a target object. Pulling the trigger  725  causes the circuitry  714  to draw power from the attached battery pack  750  and activate the internal electric motor  711 . The internal electric motor in turn actuates the internal eccentric mechanism  713 , which causes the oscillating member  719  and thus the coupled elongate monolithic blade  203  to oscillate. At the same time, the main body  716  of the locking mechanism  715  holds the elongate sheath  204  stationary. Thus, target tissues are only exposed to the cutting motions of the distal cutting end  203   b  of the elongate monolithic blade  203 . 
     In many embodiments, the hand holdable drive unit  710  will be mostly made of injection molded plastic, making the drive unit light-weight, low cost, and disposable. Further, the internal eccentric mechanism  713  can be made of lightweight aluminum and can comprise ceramic bearing surfaces. In addition to making the hand-held drive unit light-weight and low cost, the materials of the hand-held drive unit may be selected reduce the amount of noise the drive unit makes while activated. For example, the hand holdable drive unit  710  may be at least partially made of a sound absorbent resin. Alternatively or in combination, the hand holdable drive unit  710  and/or the locking mechanism  715  can be covered in a noise absorbent sheath. 
       FIG. 8A  shows the locking mechanism  715  in its unlocked configuration.  FIG. 8B  shows this with a magnified view. The locking mechanism further comprises a top portion  731 . The top portion  731  helps form a saw blade assembly reception slot  732 , comprising a portion of the oscillating member  719  shaped to be an exact match to the drive unit coupling member  212  of the surgical saw blade assembly  201  and a portion of the main body  716  shaped to be an exact match for the U-shaped proximal end  204   b  of the surgical saw blade assembly  201 . 
       FIG. 9A  shows the locking mechanism  715  in its locked configuration locking in the surgical saw blade assembly  201 .  FIG. 9B  shows this with a magnified view. Moving the lever  717  from its position as shown in  FIGS. 8A and 8B  to its position shown in  FIGS. 9A and 9B  has moved and locked the top portion  731  in close contact with the main body  716 . 
     In many embodiments, the surgical saw blade system  700  may be provided, e.g., sold, in a kit.  FIG. 10  shows an exemplary surgical saw blade kit  101 . The surgical saw blade kit comprises the hand holdable drive unit  710 , the battery pack  750 , and a plurality of surgical saw blade assemblies  201  each configured to couple with the drive unit  710 . The surgical saw blade kit may further comprise a plurality of sheathless monolithic surgical saw blades  270  configured to couple with the drive unit  710 . Each of the surgical saw blade assemblies  201  and sheathless monolithic surgical saw blades  270  may have distal cutting ends  203   b  of different sizes, shapes, materials, cutting edge arrangement, teeth size, teeth shape, teeth number, etc. for different bone cutting applications. For example, a sheathless monolithic surgical saw blade  270   a  may comprise a plurality of elongate support member  276 . In some embodiments, the surgical saw blade kit  101  may further comprise at least one cutting guide  1011 . The cutting guides  1011  will typically fit on the cut end of a patient&#39;s femur or tibia to facilitate the correct positioning of bone cuts. The cutting guides  1011  may be similar to those shown in U.S. Design patent No. 29/335,690. 
     While the above is a complete description of the preferred embodiments of the invention, various alternatives, modifications, and equivalents may be used. Therefore, the above description should not be taken as limiting in scope of the invention which is defined by the appended claims.