Abstract:
This disclosure describes techniques and devices for improvement of surgical outcomes for tissue removal surgeries. A surgical instrument with adjustable and selective resection is described. The disclosed devices and methods allow selective tissue removal.

Description:
[0001]    This application claims priority under 35 USC §119 to U.S. Provisional Application No. 62/354,515, which was filed on Jun. 24, 2016 and is herein incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates to a surgical device for soft tissue treatment, including devices and methods for selectively cutting and removing tissues. 
         [0003]    Tendon injuries are commonly caused by repeated tendon strain, and can range from simple micro tears with inflammation to complete tears and ruptures. Healthy tendons include mature, highly-organized, type I collagen fibers, which are capable of withstanding relatively large tensile loads. A typical tendon injury, or tendinopathy, may be marked by an increased presence of immature, type III collagen, characterized by a loose fibril organization. Increased type III collagen disrupts type I collagen alignment, potentially leading to a loss in strength and increased water retention of the tendon, which in turn, contributes to the cycle of injury and may lead to painful nerve impingement. 
         [0004]    In order to treat tendon or other connective tissue injuries or diseases, minimally invasive devices and techniques for selectively removing soft tissues or portions of soft tissue, like type III collagen, while leaving healthy tissue undisturbed are desired. Conventional minimally invasive techniques may be performed using multiple instruments and entry points into the body. Such techniques may also require various compounds or equipment to enable visualization of a surgical site. A device that may reduce the number of entry points or instruments used, safely dislodge and remove pathologic tissue while leaving healthy, native tissues undisturbed, would provide significant advantages to surgeons and patients 
         [0005]    The present disclosure provides surgical devices and methods for selectively treating soft tissue. 
       BRIEF SUMMARY 
       [0006]    In one embodiment, a surgical instrument includes a handle located at a proximal end of the surgical instrument adapted to be gripped by a user. The surgical instrument also includes a first lumen extending along a longitudinal axis of the surgical instrument from the proximal end to a distal end of the surgical instrument. An inner bore of the first lumen extends from an open proximal terminal end of the first lumen to a closed distal terminal end of the first lumen. The first lumen also includes a nozzle formed in a side wall proximate to the closed distal terminal end that is configured to enable a jet of fluid to exit the nozzle. The jet of fluid can selectively cut tissue and can provide a suction force to remove and/or evacuate tissue. 
         [0007]    The surgical instrument additionally includes a second lumen extending adjacent to the first lumen with an inner bore of the second lumen extending from an open proximal terminal end of the second lumen to a closed distal terminal end of the second lumen. The inner bore of the second lumen has an inner diameter greater than an inner diameter of the first lumen. The second lumen also includes an aperture disposed opposite of the nozzle to receive therein the jet of fluid exiting the nozzle. When the surgical instrument is in operation a cutting and suction force is formed at the aperture of the second lumen to selectively remove a first tissue type from different tissue types located in a surgical site. 
         [0008]    In another embodiment, a method of using a surgical instrument includes selecting a water jet cutting or suction force level on a surgical instrument to provide an adjustable cutting and suction force level; and inserting the surgical instrument into a surgical site. The method also includes creating the cutting and suction force with the surgical instrument within the surgical site by operation of the surgical instrument with the selected cutting and suction force level. The cutting and suction force is created by pumping a fluid through a nozzle of a first lumen of the surgical instrument into an aperture of a second lumen of the surgical instrument. The method further selectively cuts, a first tissue type from multiple (two or more) tissue types within the surgical site and evacuates, by the suction force, the cut first tissue type from the surgical site through the second lumen of the surgical instrument. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The accompanying figures illustrate one or more embodiments of the invention. The drawings are not necessarily to scale. The present invention is illustrated by way of example, and not limitation, in the accompanying figures wherein: 
           [0010]      FIG. 1  is a perspective view of a surgical instrument according to an exemplary embodiment. 
           [0011]      FIG. 2  is a side view with hidden lines visible of a first lumen of the surgical instrument according to an exemplary embodiment. 
           [0012]      FIG. 3  is a side view with hidden lines visible of a second lumen of the surgical instrument according to an exemplary embodiment. 
           [0013]      FIG. 4A  is a side view with hidden lines visible of an assembled first lumen and second lumen of the surgical instrument according to an exemplary embodiment. 
           [0014]      FIG. 4B  is a cross-sectional view of an assembled first lumen and second lumen of the surgical instrument according to an exemplary embodiment. 
           [0015]      FIG. 5  is a side view of the distal end of the surgical instrument according to an exemplary embodiment. 
           [0016]      FIG. 6  is a side view with hidden lines visible of a jet of fluid traveling through the surgical instrument according to an exemplary embodiment. 
           [0017]      FIG. 7  is an exemplary sequence in a method of removing a selected tissue from a surgical site according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Reference will now be made in detail to various embodiments of the disclosed devices and methods, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
         [0019]    In this application, the use of the singular includes the plural unless specifically stated otherwise. In this application, the use of “or” means “and/or” unless stated otherwise. Furthermore, the use of the term “including”, as well as other forms, such as “includes” and “included”, is not limiting. Any range described herein will be understood to include the endpoints and all values between the endpoints. Multiple will be understood to refer to two or more. 
         [0020]    The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. All documents, or portions of documents, cited in this application, including but not limited to patents, patent applications, articles, books, and treatises, are hereby expressly incorporated by reference in their entirety for any purpose. 
         [0021]    Current minimally invasive surgical techniques may cause damage to tissues that are not targeted during a surgical procedure. The introduction of multiple entry points and introducing foreign visualization compounds to the body may create trauma that may prolong patient recovery times and increase the overall cost associated with non-invasive procedures. Current minimally invasive surgical techniques could be improved by enabling the selective removal of tissues from a surgical site. Therefore, there is a need for a method to effectively and safely remove pathologic tissues while minimizing trauma at a surgical site by using a single device, and/or to selectively remove types of tissue. 
         [0022]    Embodiments of the present surgical instruments and methods allow for selective removal of tissue from a surgical site that limits the number of entry points and/or amount of foreign compound introduced into the body. In one embodiment, the surgical instrument is configured to create a cutting and suction force between a first lumen and second lumen. The cutting and suction force selectively removes a specified tissue type from the surgical site, and the level of force may be adjusted to target a certain soft tissue by setting the fluid pressure travelling through a first lumen. The removed tissue is evacuated with a moving fluid through the second lumen. As such the water jet results in a cutting force and suction force, thereby allowing cutting and removal of tissue with one device. 
         [0023]      FIG. 1  is a perspective view of a surgical instrument  100  according to an exemplary embodiment. The surgical instrument  100  includes an insertion end  110  attached to a handle  120 . The insertion end  110  includes a first lumen  113  and a second lumen  116  extending through or otherwise attached to the handle  120 . The first lumen  113  and the second lumen  116  are depicted and described further in accord with  FIGS. 2 and 3 , respectively. The handle  120  and/or lumens are connected to a pump assembly  130 . The pump assembly  130  provides a jet of fluid travelling distally along first lumen  113 . When the jet of fluid travels from the first lumen  113  to the second lumen  116  at the distal end  111  of the insertion end  110 , a cutting and suction force is generated, which can allow selective removal of tissue. The distal end  111  is depicted and described further in accordance with  FIG. 5 . 
         [0024]    The term “lumen” as used herein will be understood to refer to a structure that includes a wall with an open passageway therethrough. Although lumen may otherwise refer to an opening or passage within a tube, it will be understood in the present disclosure to refer to the physical tube or structure itself, and the “first lumen” and “second lumen” will be understood to also include an “inner bore” as discussed below. 
         [0025]    Further, although the first lumen  113  and second lumen  116  are illustrated as straight tubes or rod-like structures, other shapes may be used. For example, the lumens may be curved or angled to allow access to specific anatomic locations. As such, although being illustrated as straight structures, other configurations may be included. 
         [0026]    A user may adjust the pressure of the jet of fluid with an adjustor  135 . The jet of fluid is provided through a supply line  140 . The jet force is used to cut or resect tissue in a surgical site. Further, the level of force, which can be set by the adjustor  135 , can determine the type of tissue cut and removed within the surgical site. The cutting and removal of tissue is discussed with more detail below. Cut tissue is evacuated with a moving fluid at the insertion end  110 , through the second lumen  116  and/or handle  120 , to the evacuation lumen  150 . 
         [0027]    The pump assembly  130  may be any power source connectable to the open proximal terminal end of the first lumen  113  that is suitable to create the suction force at an aperture or opening  118  of the second lumen  116 . The aperture or opening  118  is depicted and described further in accord with  FIG. 3 . The pump assembly  130  may be a pump cartridge, peristaltic pump, a configuration with a piston for pumping the jet of fluid through the surgical instrument  100 , or any other pump suitable for generation of the jet. The piston may be powered by a transmission or any other suitable powering means. In one embodiment, the pump assembly  130  delivers a pressurized jet of fluid. In one embodiment, the jet of fluid is water. As an example, the pump assembly  130  may pump a fluid into the first lumen  113  to form the jet of fluid exiting a nozzle or opening  115 . The nozzle or opening  115  is depicted and described further in accord with  FIG. 2 . 
         [0028]    The supply line  140  may include an inlet line adapted to connect with a fluid source. In one embodiment, the supply line includes a spike or other connector (e.g., Luer, threaded, or other connector) to attach to a fluid source. In one embodiment, the fluid source is an IV bag of fluid. The supply line  140  may further include a line clamp  141  configured to stop flow of the fluid from the fluid source. The supply line  140  may be composed of high pressure tubing. 
         [0029]    In some embodiments, the amount of cutting and suction force generated in the surgical instrument  100  may be controllable by a user of the surgical instrument. In one embodiment, the amount of cutting and suction force produced in the surgical instrument  100  may be controlled by the user of the surgical instrument through a console  125 . The console  125  may be a computing device or a mechanical device. For example, a console  125  may include an adjustor  135  operable to control the pressure of the fluid provided to the first lumen  113 . The pressure of fluid travelling through the first lumen  113  can affect or determine the amount of force generated between the first lumen  113  and second lumen  116 . 
         [0030]    In one embodiment, the adjustor  125  may be a keypad in digital or mechanical communication with the pump assembly  130  and able to send commands to the pump assembly  130 . In another embodiment, the console  125  may be a user interface provided by a tablet or other computing device, and the adjustor  135  may be a user interface element displayed thereon that is operable to accept commands for controlling the pump assembly  130 . It will be appreciated that in other embodiments, the adjustor  135  may be a mechanical device such as a clamp or similar device operable on the fluid line being provided to the surgical instrument  100  without the use of a console  125 . The adjustor  135  is discussed further below. 
         [0031]    Alternatively, in another embodiment, the surgical instrument  100  may be configured to operate with only a pre-determined amount of water jet force and the force in such a case may not be adjustable by a user of the surgical instrument. In addition, in other embodiments, a controller is placed elsewhere to enable more convenient access to a user. For example, in one embodiment, the handle  120  is equipped with controllers  121 , which allow manual adjustment directly by a user (e.g., by controlling a valve or other mechanism within the device). Alternatively, or additionally, the instrument  100  can include other control mechanisms, e.g., foot pedals, to allow control without interruption of a procedure by the user holding the instrument  100 . 
         [0032]      FIG. 2  is a side view with hidden lines visible of a first lumen  113  of the surgical instrument  100  according to an exemplary embodiment. The first lumen  113  extends along a longitudinal axis of the surgical instrument  100  from a proximal end  112  of the handle  120  to a distal end  111  of the surgical instrument  100 . Inner bore  114  of the first lumen  113  extends from an open proximal terminal end of the first lumen  113  to a closed distal terminal end of the first lumen  113 . The first lumen  113  guides fluid from the pump assembly  130  to the nozzle or opening  115 . The nozzle or opening  115  is formed in a side wall proximate to the closed distal terminal end of the first lumen  113 . 
         [0033]    In some embodiments, the inner diameter of the first lumen  113  is 0.013 inches. In some embodiments, the diameter of the nozzle or opening  115  is 0.008 inches. In certain embodiments, the distal end of the nozzle or opening  115  is disposed 0.015 inches from the distal end of the first lumen  113 , but variations may be made depending on the specific instrument size. 
         [0034]    The open proximal terminal end of the first lumen  113  may be connectable to an energy source console. The energy source console is configurable to drive the surgical instrument  100  with an adjustable energy flow to adjust the cutting and suction force. In some embodiments, the energy source console includes the pump assembly  130 , supply line  140 , and the adjustor  135 . 
         [0035]      FIG. 3  is a side view with hidden lines visible of a second lumen  116  of the surgical instrument  100  according to an exemplary embodiment. The second lumen  116  includes an aperture or opening  118  configured to receive the jet of fluid travelling through nozzle or opening  115  of the first lumen  113 . 
         [0036]    In one embodiment, the inner diameter of the second lumen  116  is 0.05 inches. In another embodiment, the aperture or opening  118  is 0.065 inches in length. In another embodiment, the distal end of the aperture or opening  118  is disposed 0.081 inches from the distal end of the second lumen  116 . 
         [0037]    In one embodiment, the open proximal terminal end of the second lumen  116  is connectable to the evacuation lumen  150 . In one embodiment, the second lumen  116  is connected to the evacuation lumen  150  through the handle  120 , as depicted in  FIG. 1 . Tissue and fluid received by the second lumen  116  is transported to the evacuation lumen  150 . In some embodiments, the evacuation lumen  150  is in communication with a receptacle for storing biological materials such as tissue and fluid. 
         [0038]      FIG. 4A  is a side view with hidden lines visible of an assembled first lumen  113  and second lumen  116  of the surgical instrument  100  according to an exemplary embodiment. The second lumen  116  is disposed parallel to the first lumen  113  such that the aperture or opening  118  is disposed across from or otherwise aligned with the nozzle or opening  115  and configured to receive the jet of fluid. The second lumen  116  extends parallel to the first lumen  113  along the longitudinal axis of the surgical instrument  100 , an inner bore  117  of the second lumen  116  extending from an open proximal terminal end of the second lumen  116  to a closed distal terminal end of the second lumen  116 . The jet of fluid passing through nozzle  115  to aperture  118  enables the generation of a cutting and suction force. Creation of the cutting suction force is described in more detail below. 
         [0039]      FIG. 4B  is a cross-section view of an assembled first lumen  113  and second lumen  116  of the surgical instrument  100  according to an exemplary embodiment. In some embodiments, the inner bore  117  of the second lumen  116  has an inner diameter greater than an inner diameter of the first lumen  113 . In various embodiments, the width of nozzle or opening  115  is smaller than the width of the aperture or opening  118 . In certain embodiments, the first lumen  113  is connected to the second lumen  116  by mechanical fixation, e.g., by welding, clamping, or forming as a unitary structure. 
         [0040]      FIG. 5  is a side view of the distal terminal end  111  of the surgical instrument  100  according to an exemplary embodiment. In one embodiment, distal terminal ends  510  and  520  of the first lumen  113  and the second lumen  116 , respectively, are closed. In certain embodiments, the closed distal terminal end  510  of the first lumen  113  is shaped to assist moving the insertion end  110  through tissue of a patient. For example, the insertion end  110  may be inserted through dermal, fascial, muscular, adipose, or connective tissue (or any other anatomically reasonable tissue) to reach a surgical site. In one embodiment, the closed distal terminal end  520  of the second lumen  116  extends further than the closed distal terminal end of the first lumen  113 . In an embodiment, the closed distal terminal end  520  of the second lumen  116  is pointed or beveled. 
         [0041]    In one embodiment the insertion end  110  may be guided with the aid of ultrasound or other suitable imaging techniques. In an embodiment, ultrasound may be used to identify pathologic tissue in a joint or other structure without the aid of fluids. Pathologic tissue may be scar tissue, diseased tissue, dead tissue, inflamed tissue, or otherwise undesirable tissue. The insertion end  110  may be guided to the pathologic tissue to remove the identified tissue with a suction force. In an embodiment, the pathologic tissue is type III collagen. 
         [0042]    In certain embodiments, diseased tissue or tissue otherwise desirable to remove is identified in an elbow joint or other musculo-skeletal structure. In some embodiments, the angle of the nozzle or opening  115 , alignment of insertion end  110  and aperture or opening  118 , with relation to second lumen  116  and the surgical site prevents dense tissue from being cut and removed by surgical instrument  100  because, in certain cases, it is too fibrous or is otherwise not as easily cut or removed as other tissue. For example, type I collagen has a highly aligned and densely packed structure, capable of withstanding high tensile forces. In contrast, type III collagen is less uniformly aligned and is not capable of withstanding large mechanical forces. As such, type III collagen may be removed at suction levels that may leave nearby type I collagen undisturbed. 
         [0043]    In an embodiment, the surgical instrument  100  is suitable for use in different types of living tissue. In certain embodiments, the surgical instrument  100  is suitable for use in human tissue. In some embodiments, the surgical instrument  100  is suitable for use in joints or other musculo-skeletal structures. 
         [0044]    In one embodiment, the surgical instrument  100  may be used to remove pathologic tissue from joints. In one example, the surgical instrument  100  may be used to remove pathologic tissue from tendons in elbow joints. The suction force can be adjusted to draw in or remove only selected tissue types, such as type III collagen or other tissue that is potentially pathologic, without disturbing other tissue types in the surgical site, such as type I collagen of healthy tendons. Specifically, different types of tissue withstand different thresholds of cutting and/or suction force, so by controlling the water jet force the types of tissue being removed from the surgical site can be controlled. 
         [0045]    In some embodiments, the surgical instrument  100  may be utilized to remove pathologic tissue from different areas of the body, including without limitation, elbow, shoulder, knee, hip, ankle, or wrist joints. In one embodiment, the surgical instrument  100  may be utilized for removal of soft tissue in orthopedic procedures. 
         [0046]      FIG. 6  is a side view with hidden lines visible of a jet of fluid  610  traveling through the surgical instrument  100  according to an exemplary embodiment. The water jet force  620  is created when the jet of fluid  610  enters the aperture or opening  118  from the nozzle or opening  115 . The jet of fluid  610  is a type of fluid capable of being pressurized and dispersed through the nozzle  115 . In one embodiment, the fluid is water. In an embodiment, the jet of fluid  610  may leave the nozzle or opening  115  at a 55° angle relative to the opposing aperture or opening  118  of the second lumen  116  of the surgical instrument  100 . 
         [0047]    The jet of fluid  610  provided through supply line  140  may have a pressure set using the adjustor  135  and console  125  (or other control means) to produce an adequate cutting and/or suction at the distal end  111  to safely resect pathologic tissue. The pressure of the jet of fluid  610  can be about, more than about, or less than 100, 200, 400, 600, 800, 1,000, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 6,500, 7,000, 7,500, 8,000, 8,500, 9,000, 9,500, 10,000, 12,000, 14,000, 16,000, 18,000, or 20,000 psi. These values can be used to define a range, such as that from about 2,000 to about 14,000 psi, or from about 6,000 to 18,000 psi. 
         [0048]    The cutting and/or suction force may be increased by increasing the pressure of the jet of fluid  610 . As noted above, the pressure of the jet of fluid  610  may be increased or decreased by a user of the surgical instrument  100  via an adjustor  135 . In one embodiment, the adjustor may be a manual tab for adjusting a power level of the surgical instrument  100 , such as a wheel, knob, or lever. In some embodiments, the adjustor  135  has a fixed number of settings designating predetermined pressures for the jet of fluid  610 . Table 1 illustrates exemplary pressure levels for water within the jet. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Exemplary power levels and corresponding average pressures 
               
             
          
           
               
                   
                 Power Level 
                 Average Pressure (psi) 
               
               
                   
                   
               
             
          
           
               
                   
                 1 
                 2395 
               
               
                   
                 2 
                 3574 
               
               
                   
                 3 
                 4880 
               
               
                   
                 4 
                 6244 
               
               
                   
                 5 
                 7662 
               
               
                   
                 6 
                 9078 
               
               
                   
                 7 
                 10498 
               
               
                   
                 8 
                 12020 
               
               
                   
                 9 
                 13082 
               
               
                   
                 10 
                 14065 
               
               
                   
                   
               
             
          
         
       
     
         [0049]    In one embodiment, the pressure of the jet of fluid  610  pumped through the surgical instrument  100  ranges from 2,395 psi to 14,065 psi. In another embodiment, the pressure of the jet of fluid  610  ranges from 2,395 psi to 12,020 psi, or from 2,000 to 12,000 psi. It will be appreciated that other pressure ranges of greater and lesser values are also within the scope of the present invention. 
         [0050]    The adjustor  135  (or other component) may include an adjustment means for adjusting the pressure of the jet of fluid through the pump assembly  130 . The adjustment means may be at least one knob, button, lever, keypad, or any other suitable means for adjusting the pressure of the jet of fluid  610 . In some embodiments, the adjustment means enables a user of the surgical instrument  100  to select a predetermined power level of pressure. In certain embodiments, the user can select one of ten power levels. In one embodiment, the surgical instrument  100  is configured to provide a predetermined pressure and does not include an adjustor. 
         [0051]      FIG. 7  is a flowchart depicting an exemplary sequence in a method of removing a selected tissue from a surgical site according to an exemplary embodiment. The method begins after a surgical site is selected at Step  710  when a water force level is selected by a user of the surgical instrument. For example, the user may use an adjustor on the surgical instrument  100  to select a pre-determined power level. A suitable surgical site may be a joint in a patient. In one embodiment, the surgical site is an elbow joint. The water force level can be selected after at least a first tissue type is identified within the surgical site so that an appropriate suction force level is determined, or based on expected levels for known tissue types. The tissue type may be identified through ultrasound or other suitable imaging techniques, or by surgical experience or visual inspection. In some embodiments, multiple tissue types are identified. 
         [0052]    At Step  720 , a surgical instrument  100  is inserted into the surgical site. In one embodiment, an incision or puncture is made in a surgical site to allow insertion of the surgical instrument. In an embodiment, the surgical instrument  100  may be shaped to move through tissue of a patient. In another embodiment, a closed distal terminal end  520  of the second lumen  116  of the surgical instrument  100  is shaped to move through tissue of a patient. 
         [0053]    At Step  730 , a cutting and suction force is created within the surgical site using the surgical instrument  100  with the selected water force level. In one embodiment, the water force is created by pumping a fluid through the surgical instrument  100 . In another embodiment, the water force is created by pumping a fluid through a nozzle or opening  115  of a first lumen  113  of the surgical instrument  100  into an aperture or opening  118  of a second lumen  116  of the surgical instrument  100 . In an embodiment, the fluid is a jet of water  610 . As described herein, in one embodiment, the pressure of the jet of water  610  may be adjusted to control the strength of the cutting or suction force. 
         [0054]    At Step  740 , the first tissue type is selectively cut or resected from the surgical site as a result of operation of the surgical instrument  100  with the selected cutting or suction force level. As an example, type III collagen can be removed from an elbow joint without removing type I collagen tissue by creating a cutting and/or suction force of sufficient strength to resect type III collagen without resecting type I collagen. 
         [0055]    At Step  750 , the cut or resected first tissue type is evacuated from the surgical site. In some embodiments, the cut or resected first tissue type is evacuated from the surgical site with fluid. In some embodiments, the cut or resected first tissue type and the fluid are evacuated through the second lumen  116  of the surgical instrument  110  to an evacuation lumen  150 . 
         [0056]    The tissue type(s) may be defined by a tissue density or other tissue property. For example, if a tendon or other tissue has been damaged or is diseased, the tendon may include more than one type of tissue, as the term “tissue type” should be presently understood. In one embodiment, the different tissue types may refer to healthy tissue and diseased tissue. In another embodiment, different tissue types may be identified by variations in tissue density (e.g., due to damage, disease, inflammation, etc). For example, if diseased or damaged tissue is to be removed from within or surrounding a tendon, different tissue types may include tendinous tissue or scar or damaged tissue surrounding or within the tendon, and the tissue types may have variations in density. For example, healthy tendon will be understood to have a first density while diseased tissue may have a second density, and as such, different tissues can be identified within a common anatomic structure (e.g., a single tendon), or in a separate structure (e.g., a tendon and surrounding or nearby scar). In some embodiments, a healthy tissue may have densities, for example, from 1,900 kg/m 3  to approximately 1,700 kg/m 3 , while a second tissue type associated with the same tendon, but being damaged or diseased may have a density, for example, from 1,100 kg/m 3  to approximately 1,400 kg/m 3 ; 1,200 kg/m 3  to approximately 1,350 kg/m 3 ; or other ranges therebetween. 
         [0057]    Certain types of tendinopathy may be treated using the disclosed devices and methods. For example, calcific tendinopathy of the shoulder, elbow, knee or other joints may be treated. Calcific tendinopathy can include damaged tendon with areas of weakness, which can also lead to significant morbidity due to pain associated with damaged tissue. Accordingly, removal of tissue affected by such conditions can be beneficial. 
         [0058]    Since certain changes may be made without departing from the scope of the present invention, it is intended that all matter contained in the above description or shown in the accompanying drawings be interpreted as illustrative and not in a literal sense. Practitioners of the art will realize that the sequence of steps and architectures depicted in the figures may be altered without departing from the scope of the present invention and that the illustrations contained herein are singular examples of a multitude of possible depictions of the present invention. 
         [0059]    The foregoing description of example embodiments of the invention provides illustration and description, but is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. For example, while a series of acts has been described, the order of the acts may be modified in other implementations consistent with the principles of the invention. Further, non-dependent acts may be performed in parallel. 
         [0060]    It should be appreciated that the various embodiments individually described herein may be practiced in combination in certain circumstances without departing from the scope of the present invention. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of this disclosure. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the disclosed devices and methods being indicated by the following claims. 
       Example: Tendinopathy Treatment Model 
       [0061]    The following experiment demonstrates that the disclosed devices are capable of selectively removing collagen with different densities. 
         [0062]    An in vitro study was performed to determine the ability of the disclosed device to remove pathologic tissue. 
         [0063]    Initially, bovine flexor tendons from the ankle joint were harvested and characterized. Ultrasound was used to measure the density of the harvested tendon, which was measured to be approximately 1,900 kg/m 3 . Tendons were separated into three groups, and subjected to injections of clostridial collagenase type 1 (290 units/mg, SIGMA-ALDRICH CORP.) in a dose escalation study from 1, 10, and 50 mg/ml. No collagenase was administered to a fourth, control group. 
         [0064]    Following collagenase treatment, there was a significant decrease in tendon density in a dose-dependent manner. The tendon density of the 1 mg/ml group dropped from approximately 1,900 kg/m 3  to approximately 1,500 kg/m 3  after 24 hours. 72 hours after collagenase injection, the density further decreased to approximately 1,400 kg/m 3 . The tendon group that was administered 50 mg/ml doses showed a similar pattern, resulting in complete degradation after 3 days. 
         [0065]    The 1, 10, 50 mg/ml, and control groups were treated using the disclosed device and methods at various pressure settings. The untreated, control tendon group was resistant to debridement of tissue up to the highest pressure setting. Additionally, neither tissue injury nor removal of any kind occurred. The 1 mg/ml group demonstrated similar results when treated with the disclosed device. Minimal tissue removal was observed, until the highest settings were tested. Removal of low density tissue was observed when the 10 and 50 mg/ml collagenase dosage tendon groups were treated with the disclosed device. Particularly, removal of tissue with densities less than around 1,200 to 1,300 kg/m 3  was achieved. 
         [0066]    The foregoing experiment indicated that the disclosed device was able to selectively resect tissues. Particularly, the disclosed device exhibited the capability to safely remove lower-density soft tissue while leaving higher-density soft tissue unperturbed.