Abstract:
An impactor having a housing including an upper portion and a lower portion at least a part of which extends perpendicularly from the upper portion, a ram having a first end positioned in the upper portion and positioned in axial alignment with the lower portion, an opposite end of the ram extending from the lower portion of the housing, at least one drive assembly including a first drive shaft operably coupled to a cam shaft, a cam operably coupled to the cam shaft, a cam operably coupled to the cam shaft, the drive shaft operably connectable to motor, wherein the cam is operable to rotate and positioned to contact the proximal end of the ram upon rotation of the cam, a circuit board comprising circuitry operable to receive instructions from a plurality of switches electrically coupled to the circuit board to operate the impactor, wherein the impactor is operable to deliver low amplitude pulsed strikes to a workpiece at variable frequencies.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/928,011 filed Jan. 16, 2014, the entirety of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to the field of impactors. More specifically it relates to medical device impactor instruments. 
       BACKGROUND 
       [0003]    Surgery, more specifically orthopedic surgery, often requires the surgeon to apply significant forces to the anatomy in order to achieve a desired result. Insertion of medical devices, particularly orthopedic, typically involves repetitive low-frequency and high magnitude forces, commonly from a mallet or hammer. These high peak impact forces predispose the bone or soft tissue to mechanical failure or injury. Furthermore, high sudden peak forces make it more difficult to center the tool or implant. 
         [0004]    For example, a surgeon may need to remove bony anatomy by chiseling. Chiseling typically requires at least two tools: a chisel with one bladed end perpendicular to the long axis of the instrument and the opposite end formed as a striking surface, and mallet used to apply force to the striking surface of the first tool. 
         [0005]    In another application, a surgeon may need to impact a device in order to modify the anatomy to receive an implantable device. In the case of an orthopedic hip implant, a surgeon may repeatedly impact a broaching device to create the desired cavity within a femur. After an implantable device has been inserted, further impact may be necessary to position the device in its desired location or secure it in place. 
         [0006]    In another application, a surgeon may need to insert a device into the anatomy. In orthopedics, examples include but are not limited to hip stems, knee replacements, shoulder replacements and various spinal devices such as interbody spacers, artificial disc replacements, interspinous devices and longitudinal members. 
         [0007]    However, challenges exist when impacting or inserting devices, include surgeon fatigue, harm to the patient, harm to the device, whether it be the instrument or implant, and the need for multiple types of impactors or inserters depending on the type of surgery being performed. 
         [0008]    The act of repeated striking an instrument with a mallet requires strength, endurance and accurate placement. In longer procedures, this activity could prematurely fatigue the user. Furthermore, when impacting with greater force or amplitude, the risk of harming the patient increases. In the example of hip replacement surgery, inserting a femoral stem under great force could fracture the femur. High amplitude impacting under lower frequency could also damage a medical implant. In the example of an Anterior Lumbar Interbody Fusion (ALIF) device, high amplitude impact forces could break the implantable device. Finally, in some instrument sets, each sample inserter may be a stand-alone device which adds weight, bulk and cost to the set. A mallet alone typically adds 2-5 pounds of weight to an instrument set. 
         [0009]    Therefore, a need exists for a medical device impactor and inserter operable to apply consistent, controlled impact at a desired amplitude and frequency. 
       SUMMARY OF THE INVENTION 
       [0010]    In accordance with one or more embodiments, medical impactors for surgical procedures are disclosed. The disclosed impactors are operable to apply consistent, controlled impact at a desired amplitude and frequency. The impactors are configured such that an actuating component will produce a repeatable force or pulse parallel to the long axis of the device. The repeated force or pulse may occur at least two times, at variable intervals, such as in short succession, and with a smaller amplitude, or force, than that of a surgical mallet operated by a surgical staff member. 
         [0011]    In some embodiments impactors are disclosed which are operable to apply low amplitude, high frequency impact. Utilizing a high-frequency impacting device with low peak force provides for the same or greater total energy of delivery and markedly less risk of injury to the tissues and patient. 
         [0012]    In further embodiments, devices are provided which may employ repetitive cyclic force greater than 2 Hz to facilitate driving, inserting, implanting, removing, relocating a device, implant or tool in bone or soft tissue for medical applications. High-frequency may be combined with static force or load. The forces applied may be axial or non-axial, translational or torsional. Devices disclosed herein may be used for orthopedic or non-orthopedic applications. 
         [0013]    In some embodiments an impactor device is a stand-alone impactor. In another embodiment, the device is operable to receive one or more attachments, optionally interchangeably, that may be fitted to the distal end of a ram of the device. 
         [0014]    In a further embodiment, an impactor device is disclosed which is operable to remove an implant. 
         [0015]    In another embodiment, an impactor is disclosed which includes a housing having an upper portion and a lower portion, at least part of the lower portion extending perpendicularly from the upper portion, a ram having a first end positioned in the upper portion and positioned in axial alignment with the lower portion, an opposite end of the ram extending from the lower portion of the housing, at least one drive assembly having a first drive shaft operably coupled to a cam shaft, a cam operably coupled to the cam shaft, the drive shaft operably connectable to motor, wherein the cam is operable to rotate and positioned to contact the proximal end of the ram upon rotation of the cam, a circuit board including circuitry operable to receive instructions from a plurality of switches electrically coupled to the circuit board to operate the impactor, wherein the impactor is operable to deliver low amplitude pulsed strikes to a workpiece at variable frequencies. 
         [0016]    The impactor may include at least one coil spring disposed annularly within the lower housing in which a portion of the ram is disposed in axial alignment within the coil spring. The impactor may include a battery electrically coupled to the circuit board. 
         [0017]    In certain embodiments the impactor is a hand-held device. 
         [0018]    In some embodiments the impactor includes at least one motor contained within the housing and operably coupled to the drive shaft. The motor may be an inserter motor electrically coupled to the circuit board and a battery or external power source, and operably coupled to the drive shaft, wherein the ram includes an inserter surface positioned to receive impact from the cam to drive the ram in the direction of the lower housing. This embodiment is useful for applications requiring insertion of an implant, chiseling, broaching and the like. 
         [0019]    In other embodiments the motor may be a remover motor electrically coupled to the circuit board and a battery or external power source, and operably coupled to the drive shaft, wherein the ram comprises a removal flange positioned to receive impact from the cam to drive the ram in the direction of the upper housing. This embodiment is useful in applications requiring removal of an implant or other workpiece. 
         [0020]    In yet further embodiments, the impactor includes an inserter motor and a remover motor electrically coupled to the circuit board, and further including at least two drive assemblies, wherein each of the inserter and remover motors are operably coupled to one of each at least two drive assemblies, wherein the ram includes an inserter surface positioned to receive impact from a first drive assembly cam to drive the ram in the direction of the lower housing, and wherein the ram includes a removal flange positioned to receive impact from a second drive assembly cam to drive the ram in the direction of the upper housing. 
         [0021]    The impactor may include a plurality of switches. For example, the impactor may include one or more of a power switch, force selection switch, fire switch, continuous mode/single mode switch operable to control the rotation of a cam between a single rotation and continuous rotation, and/or a motor selection switch, each of which is electrically coupled to the circuit board. 
         [0022]    The impactor may include one or more sensors or sets of sensors. In one embodiment the impactor includes a mounting plate mounted to the lower housing having an opening formed therein in which the ram is disposed, the mounting plate having at least one sensor electrically coupled to the circuit board, the at least one sensor operable to detect misalignment of the ram. 
         [0023]    In other embodiments the impactor may include a sensor electrically coupled to the circuit board and positioned to detect force imparted by a cam on the ram. The impactor may include a sensor electrically coupled to the circuit board and positioned to detect force imparted by a user on the impactor. 
         [0024]    The impactor in some embodiments includes a display electrically coupled to the circuit board operable to display data. The impactor may include a battery electrically coupled to the circuit board. 
         [0025]    In some embodiments the ram includes a connecting element positioned at a distal end operable to connect a tool or implant. 
         [0026]    In still a further embodiment, the impactor includes a drive assembly which includes a drive shaft having a connecting element disposed on an end opposite an end coupled to the cam shaft, the connecting element operable to connect the drive shaft to an external drive. 
         [0027]    Various further features are disclosed in the drawings and description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    For the purposes of illustration, there are forms shown in the drawings that are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
           [0029]      FIG. 1  is a top perspective view of a device according to an embodiment of the present disclosure; 
           [0030]      FIG. 1A  is rear view of an embodiment of the device of  FIG. 1 ; 
           [0031]      FIG. 1B  is a side perspective view of the device according to  FIG. 1 ; 
           [0032]      FIG. 2  is a cross-sectional view of the device according to  FIG. 1A  taken along line Z-Z according to an embodiment of the present disclosure; 
           [0033]      FIG. 3  is a cross-sectional view of the device according to  FIGS. 1 and 1A , taken along the line A-A of  FIG. 2 ; 
           [0034]      FIG. 3A  is an enlarged view of detail G of  FIG. 3  according to an embodiment of the present disclosure; 
           [0035]      FIG. 4  is cross-sectional view of the device according to  FIGS. 1 and 1A , taken along the line B-B of  FIG. 3 ; 
           [0036]      FIG. 4A  is an enlarged view of detail D of  FIG. 4  according to an embodiment of the present disclosure; 
           [0037]      FIG. 5  is a top view of the device according to  FIG. 1 , with some interior components shown in phantom; 
           [0038]      FIG. 5A  is a cross-sectional view of the device according to  FIG. 5 , taken along the line C-C of  FIG. 5 ; 
           [0039]      FIG. 5B  is an enlarged view of detail E of  FIG. 5A  according to an embodiment of the present disclosure; 
           [0040]      FIG. 6  is a perspective view of the device according to  FIG. 1  with a portion of the top housing cut away according to an embodiment of the present disclosure; 
           [0041]      FIG. 6A  is an enlarged view of detail F of  FIG. 6  according to an embodiment of the present disclosure; 
           [0042]      FIG. 7  is a perspective view of the device according to  FIG. 1  with a portion of the top housing cut away to show a drive shaft for receiving an external drive according to an embodiment of the present disclosure; 
           [0043]      FIG. 8  is a side view of an impactor/remover ram  30  having a connector end  30   a  for receiving an attachment according to an embodiment of the present disclosure; 
           [0044]      FIG. 8A  is a top view of an implantable Anterior Lumbar Interbody Fusion (ALIF) device with a means to connect to an impactor/remover ram according to an embodiment of the present disclosure; 
           [0045]      FIG. 8B  is a top view of an implantable Transforaminal Lumbar Interbody Fusion (TLIF) device with a means to connect to an impactor/remover ram according to an embodiment of the present disclosure; 
           [0046]      FIG. 8C  is top view of an implantable Posterior Lumbar Interbody Fusion (PLIF) device with a means to connect to an impactor/remover ram according to an embodiment of the present disclosure; 
           [0047]      FIG. 9  is a side view of an impactor/remover ram  30  having a connector end configured to receive an attachment according to an embodiment of the present disclosure; 
           [0048]      FIG. 9A  is a top view of a sharp-tip distal end device with a means to connect to an impactor/remover ram according to an embodiment of the present disclosure; 
           [0049]      FIG. 9B  is a top view of a tamp distal end device with a means to connect to an impactor/remover ram according to an embodiment of the present disclosure; 
           [0050]      FIG. 9C  is a top view of a wide chisel distal end device with a means to connect to an impactor/remover ram according to an embodiment of the present disclosure; 
           [0051]      FIG. 10  is a perspective view of a threaded bore  30   b  for receiving an attachment according to an embodiment of the present disclosure; 
           [0052]      FIG. 11  is a schematic of elements coupled to a printed circuit board according to an embodiment of the present disclosure; 
           [0053]      FIG. 12  is a schematic of elements controlled through a printed circuit board according to an embodiment of the present disclosure; 
           [0054]      FIG. 13  is a schematic of elements controlled through a printed circuit board according to an embodiment of the present disclosure; 
           [0055]      FIG. 14  is a schematic of elements controlled through a printed circuit board according to an embodiment of the present disclosure; and 
           [0056]      FIG. 15  is a schematic of elements controlled through a printed circuit board according to an embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0057]    The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. In the drawings, the relative sizes of regions or features may be exaggerated for clarity. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0058]    It will be understood that when an element is referred to as being “coupled” or “connected” to another element, it can be directly coupled or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly coupled” or “directly connected” to another element, there are no intervening elements present Like numbers refer to like elements throughout. As used herein the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0059]    In addition, spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. Thus, the exemplary term “under” can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
         [0060]    Well-known functions or constructions may not be described in detail for brevity and/or clarity. 
         [0061]    Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Unless otherwise indicated or defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. The terminology used herein is for describing particular embodiments only and is not intended to be limiting. 
         [0062]    Embodiments of the present invention are described with reference to the FIGS. Now referring to  FIGS. 1-3 , an impactor  2  operable to impart impact force and/or removal force includes a housing  10 , display  16 , ram  30 , motors  40  and  46 , cam shafts  50  and  54 , cams  52  and  56 , multifunction sensor  60 , spring  70 , mounting plate  80 , strike alignment sensors  81  and circuit board  92 . The impactor  2  may include a battery  90  to power the impactor  2 . In other embodiments the impactor may use an external power source, such as AC power or an external drive. 
         [0063]    The impactor  2  may be any size and dimension. In one embodiment the housing  10  is sized and dimensioned to fit comfortably in the hand of an adult user. The housing  10  may include upper and lower housing elements  12  and  14 , respectively. In embodiments for a hand-held device, upper housing  12  includes an exterior surface that may be for example, and not by way of limitation, about 3-15 cm in width and about 3-20 cm in length. In other embodiments the exterior surface may be for example from 5-12 cm in width and 5-15 cm in length. The upper housing  12  may include a plurality of switches  11 ,  18 ,  19 ,  20  and  22 , and one or more indicators  16  as described further herein below. It will be understood by those skilled in the art that the location, type and orientation of the switches may be varied depending on the configuration of the housing  10  and the arrangement of elements of the impactor  2 . As shown, the upper housing  12  includes a display  16  such as but not limited to a LCD display operable to permit a user to monitor various functions of the device. The upper housing  12  includes force selection switch  18 , power switch  19 , continuous mode/single mode switch  20 , stroke direction control switch  22 , and fire switch  11 . Upper housing  12  may further include mounts for cam shafts  50  and  54  and multifunction sensor  60 . 
         [0064]    Lower housing  14  houses ram  30  and spring  70  mounted annularly within a lower section of the lower housing  14 . The lower housing  14  may include mounts for motors  40  and  46 , mounting plate  80 , battery  90  and circuit board  92  and electrical sensors tied into the circuit board  92 . With further reference to  FIG. 4 , the lower housing  14  may include a work zone light  17  to illuminate a work area for a user. 
         [0065]    It will be understood by those skilled in the art that the location, type and orientation of elements contained or mounted in the lower housing  14  may be varied depending on the configuration of the housing  10  and the arrangement of elements of the impactor  2 . 
         [0066]    The ram  30  is positioned and operable to move in a reciprocating fashion within the housing  10 . Mounting plate  80  serves as a guide aligning the ram  30  in the housing  10  and also as a stop for spring  70 . Fasteners  13  such as but not limited to screws may be employed to retain mounting plate  80  in position on housing  10 . The ram  30  imparts force on a work piece, whether that work piece is an implant, tissue such as bone or the like. Ram  30  includes flanges  32 ,  33  and  37 . Flange  32  is operably positioned to apply force to spring  70 . It will be noted the impactor  2  may employ a single spring, as shown for example in  FIG. 2 , disposed such that flange  32  is positioned between coils of the spring. In other embodiments, two springs may be employed, with one spring positioned above the flange  32  and the other positioned below the flange  32 , toward the distal end of the ram  30 , i.e., the end of the ram  30  that is outside the housing  10 . In either case, depending on the motor actuated for operation, i.e., the remover motor  46  or the inserter motor  42 , the spring  70  is operable to restore the ram  30  to a starting, or baseline position after each cam rotation. 
         [0067]    Flange  33  is positioned closer to the opposite end of the ram  30 , adjacent the mounting plate  80 . 
         [0068]    Motors  40  and  46  may be any suitable motor. In one embodiment the motors  40  and  46  are universal motors which may employ speed control such as a centrifugal mechanism or resistance method. Universal motors offer the design choice of AC or DC power, have a high starting torque and variable speed characteristics. 
         [0069]    With reference to  FIG. 2 , motor  46  is a remover motor, and includes drive shaft  48 . With further reference to  FIGS. 3 and 3A , drive shaft  48  is coupled to remover cam shaft  54 , which is in turn is coupled to remover cam  56 . When the remover motor  46  is actuated, remover cam  56  turns and a lobe thereof (which may include lobes identical to the lobes shown for inserter cam  52  in  FIGS. 4 and 4A ) strikes the ram removal flange  37 , driving the ram  30  upward, providing a removing force. Spring  70  is compressible between mounting plate  80  and flange  32  upon upward force imparted by the remover cam  56 . After a lobed portion of cam  56  passes through contact with the ram removal flange  37 , the spring  70  restores the ram  30  to the baseline position, until a lobe of the remover cam  56  again strikes the ram removal flange  37 , whereupon the removing force is repeated. 
         [0070]    Now referring to  FIGS. 4 and 4A , motor  40  operates in a similar fashion, employing drive shaft  42  coupled with cam shaft  50  and cam  52 . With further reference to  FIG. 6A , in one embodiment drive shaft  42  is operably connected to cam shaft  50  using a worm gear arrangement. Cam  52  is operable to rotate such that one of lobes  52   a ,  52   b  strikes ram surface  39  to drive ram  30  in a downward direction. Spring  70  provides a restoring force as described above. Continued rotation of the lobed cam  52  produces a cycle of applied insertion force and subsequent recovery to a baseline position. Accordingly, and in a similar manner as described for motor  46 , a pulsed application of force is produced. 
         [0071]    As shown in  FIG. 3A , the impactor  2  may include one or more sensors or load cells  64  electrically coupled to the circuit board  92  and positioned to detect impact force between cam  52  and ram surface  39  and between cam  56  and ram remover flange  37 . The measured data may be displayed in display  16 . 
         [0072]    With further reference to  FIGS. 5-6A , mounting plate  80  includes one or more strike alignment strain sensors  81  electrically coupled to circuit board  92 . The strike alignment strain sensors  81  may be positioned in bores formed in the edge of the mounting plate  80 , for example, bores separated by about 90 degrees along the perimeter of the mounting plate  80 . The strike alignment strain sensors  81  are thus positioned to measure load applied perpendicular to the axis of the ram  30  to detect misalignment of the impactor  2 . In some embodiments, depending on the programming of the circuit board  92 , misalignment of the impactor  2  may produce an audible alarm, a message on the display  16 , and/or cause the impactor to not operate. Suitable strain sensors include micro-gauge surface sensors available commercially from MicroStrain® of Williston, Vt. 
         [0073]    With further reference to  FIG. 7 , in another embodiment the impactor  2  does not include internal motors. Rather, the impactor  2  includes drive shafts  120 ,  122  each axially aligned with corresponding apertures  124  formed in housing  10 . The drive shafts  120 ,  122  each include a connector end  121  configured to connect to an external drive. Connector end  121  may be of any suitable form, including but not limited to a female element with an interior surface keyed to a corresponding male element, a bolt, quick-release coupling, etc. For example, connector end  121  may be a bore with a hexagonal cross-section for receiving a hexagonal bolt, or bit, fitted to a drive such as a powered drill. The external drive connector is connectable to one of the drive shafts  120 ,  122  via aperture  124 , depending on the direction of operation desired. 
         [0074]    With further reference to  FIGS. 8-10 , the ram  30  may include a connector end  30   a  configured to connect to a corresponding tool or implant. Connector end  30   a  may be of any suitable form, including but not limited to a female element an interior surface keyed to a corresponding male element, a bolt, screw, quick-release coupling, etc. Depending on the application, an attachment or implant may be connected to the ram  30 , employed or inserted as needed, and disconnected from the ram  30 . For example, a broaching tool may be connected to ram  30  and employed to prepare a femur for femoral stem implant in a total hip arthroplasty. The broaching tool can be removed from the impactor and replaced with a hammer attachment to assist in insertion of the femoral stem. The use of both tools is facilitated by high-frequency insertion allowing for more controlled and safer placement most likely associated with decreased injury to adjacent tissues. 
         [0075]    In a further example, an interbody cage can be fitted to the connector end  30   a  and the impactor used to insert the interbody cage into in intervertebral disk space, providing for safer insertion and decreased risk of catastrophic vertebral endplate and implant failure. After proper insertion, the interbody cage is disconnected from the connector end  30   a  and left in place. 
         [0076]    As will be apparent to those skilled in the art, there are many types of devices that may be attached to the ram  30 . Accordingly, the foregoing examples are non-limiting. 
         [0077]    Now with further reference to  FIG. 11 , all sensors, switches and displays disclosed and discussed herein are electrically connected to the circuit board  92 . Circuit board  92  is the main control hub of the device, handling commands input by virtue of the user selecting various combinations of switch positions. The circuit board  92  may include circuitry operable to measure battery charge, strike frequency, torque, current, and input from various sensors such as sensors  60  and  81  and output data for display on display  16 . The circuit board  92  may include a processor and memory to capture data for output to an external computer, server or storage device. For example, the data from sensors  81  and  60 , as well as from other sensors and detectors, may be saved in a memory, which may be part of a processor disposed on circuit board  92 . USB port  9  ( FIG. 5 ) may be disposed in housing  10  and operable for downloading stored data saved in a memory. The circuit board  92  may include a wireless card and communication means to transmit data wirelessly to a server or other computer. In either case, the data is saved and may be reviewed by the user, surgical team or others. 
         [0078]    In one embodiment display  16  is operable to display data monitored by the printed circuit board  92  concerning the impactor  2  such as but not limited to battery life, “ready” signal that the device is ready to use, frequency, force applied, overload warning, current, strike alignment, and torque 
         [0079]    Further referring to  FIG. 12 , in some embodiments the power switch  19  makes power available to the impactor  2  so that it can run. However, in some embodiments, adjusting the power switch  19  to the “on” position will not cause the impactor to begin operating. In some embodiments, the impactor will only operate if the power switch is turned “on” and the fire switch  11  is activated. In some embodiments, when the power switch  19  is turned “on” the work light  17  illuminates and/or display  16  indicates the impactor is ready to use. In the event the circuit board  92  detects a low battery charge, the circuit board  92  may cause an audible warning tone to issue, and/or cause the display  16  to show a low battery message. 
         [0080]    With reference to  FIG. 13 , strain alignment gauges  81  measure and report strain measurements to the circuit board  92 . If the measurements from the strain gauges  81  reveal equal resistance, the fire switch  11  is enabled and actuation of the fire switch  11  will start the impactor  2 . If the data from the strain alignment gauges reveal unequal force distribution, in some embodiments, depending on the programming of the circuit board  92 , misalignment of the ram is deemed present and the impactor  2  may produce an audible alarm, a message on the display  16 , and/or cause the impactor to not operate by disabling the fire switch  11 . In one embodiment, the circuit board  92  includes programming to override the disabled fire switch by the placing the stroke direction control switch  22  in a neutral position and depressing the fire switch  11  rapidly a given number of times, such as from 3-6 consecutive times. In another embodiment the override command can be canceled by cycling the power switch  19  off then on. 
         [0081]    With reference to  FIG. 14 , the stroke direction control (or motor selection) switch  22  permits a user to select the stroke direction of the impactor, i.e., removal or insertion mode. Adjusting the stroke direction control switch  22  to the “remover” position causes the impactor to deploy the remover motor  46  when the power switch  19  is in the on position and the fire switch  11  is in the “on” position. Similarly, adjustment of switch  22  to the “inserter” position causes the impactor to deploy the inserter motor  40  when the power switch  19  is in the on position and the fire switch  11  is in the on position. The display  16  may display the motor that is selected. As shown in  FIG. 3A , the impactor  2  may include one or more sensors or load cells  64  electrically coupled to the circuit board  92  and positioned to detect impact force between cam  52  and ram surface  39  and between cam  56  and ram remover flange  37 . The measured data may be displayed in display  16 . 
         [0082]    In one embodiment, the stroke direction control switch  22  is a three-position switch. When the switch is in the center, or neutral, position the impactor  2  will not fire. This allows the user to position the impactor  2  before the work begins. When the stroke direction control switch  22  is moved to either the “insert” or “remover” position, the work zone light  17  will illuminate to add extra light to the operation being performed. 
         [0083]    The amount of force that is delivered by the cams  52 ,  56  may be selected by the user by adjustment of the force selection switch  18 . In one embodiment the force adjustment switch  18  is operable to move between selectable positions to vary the speed of the motor that is being employed. The force selection switch  18  may operate by limiting the current to the motors and thereby the striking force of the cams. As will be apparent to the skilled artisan, the number of selectable positions for the force adjustment switch  18  are a matter of design choice. In some embodiments, the number of settings is from 1 to 100. In other embodiments the number of settings is from 2 and 10. In still other embodiments the number of settings is from 3 to 8. In some embodiments the setting of the force selection switch  18  may be displayed in the display  16  for ease of reference for the user. The switch  18  may be a push button that permits a user to scroll the force settings, increasing or reduce the force by repeated depressions of the switch  18 . In one embodiment, where the force selection switch  18  is a push button, depressing the button once causes the display  16  to display a power bar graph identified from 30 to 100%. A subsequent push of the button causes the display to show an increase by a given interval, such as but not limited to 10%. If no further actuations of the switch  18  are made within a given interval of time, for example, five seconds, the setting displayed is retained in the processor. The circuit board may be programmed to provide a default value on start-up of the impactor  2 . In one embodiment the default value is 30%. 
         [0084]    The continuous mode/single mode switch  20  is adjustable to permit a user to select the mode of operation of the impactor  2 . In the single mode the impactor produces one strike per activation of the fire switch  11 . In the continuous mode the selected motor will continue to operate while the fire switch  11  is depressed. The position of the continuous mode/single mode switch  20  may be displayed on display  16 . 
         [0085]    Thus, the impactor  2  may in single mode operate at a frequency decided by the user, i.e., the frequency is the desired interval between actuations of the fire switch  11 . Depending on the position of the force selection switch  18 , the amplitude of each single mode pulse can be low, high or somewhere intermediate. In continuous mode, the frequency and amplitude can be varied simultaneously. 
         [0086]    With further reference to  FIG. 15  and  FIGS. 2 ,  3  and  3 A, multifunction sensor  60  is positioned between the proximal end of the ram  30  and the housing  10  and electrically coupled to circuit board  92 . Multifunction sensor  60  includes a plurality of load cells, including but not limited to hammer strike load cells and applied pressure load cells to detect the actual force that is distributed from the cams  52 ,  56  to the ram  30 , and/or from the pressure exerted on the impactor  2  by the user. In some embodiments, depending on the programming of the circuit board, a detected force above and/or below a selected threshold may produce an audible alarm, a message on the display  16 , and/or cause the impactor to not operate. Suitable multifunction sensors and transducers are available commercially, such as from CTS Corporation of Elkhart, Ind. or Keyence Corporation of Itasca, Ill. In some embodiments the threshold force is from 0 to 1000N. 
         [0087]    Although the devices and systems of the present disclosure have been described with reference to exemplary embodiments thereof, the present disclosure is not limited thereby. Indeed, the exemplary embodiments are implementations of the disclosed systems and methods are provided for illustrative and non-limitative purposes. Changes, modifications, enhancements and/or refinements to the disclosed systems and methods may be made without departing from the spirit or scope of the present disclosure. Accordingly, such changes, modifications, enhancements and/or refinements are encompassed within the scope of the present invention.