Patent Publication Number: US-2023145877-A1

Title: Knee Distractor Apparatus and Method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation in part of U.S. Pat. Application 16/919,810 , filed Jul. 02, 2020, which is in turn a continuation in part of U.S Pat. Application 15/727,738 filed Oct. 09, 2017 and claims the benefit and priority from U.S. Provisional Pat. Application 62/407,783, filed Oct. 13, 2016, the contents and disclosure of both are incorporated herein by reference for all purposes. 
    
    
     BACKGROUND 
     Field 
     Apparatus and method for distraction (stretching and/or straightening) of injured knee joints. 
     Background 
     After knee surgery and in rehabilitation of sore and injured knees, it is important to distract (stretch or uncouple) the knee joint to prevent stiffness from becoming permanent. In athletes, this is frequently accomplished by having a trainer pull on the leg to distract the knee joint for a predetermined time period - 10 to 20 minutes is customary. In some rehabilitation and physical therapy situations, bungee cords are attached to the ankle or a leg that has an injured knee, while the patient lies down with the cord under tension - stretching or uncoupling the knee joint. Bungee cords of varying elasticities allow customization of the tension applied. These methods, however, either require manual assistance or a controlled environment (therapy session) to be satisfactorily applied. A detailed description of the problems in knee rehabilitation and the need for stretching is described in published application U.S. 2014/0088466, together with a complicated apparatus for use in therapy, the disclosure of which is incorporated herein by reference. 
    
    
     
       DESCRIPTION OF THE FIGURES 
         FIG.  1 A  is a front drawing of an embodiment of the invention showing the knee distractor in position on a leg. 
         FIG.  1 B  is a front drawing of another embodiment of the invention showing the knee distractor in position on a leg. 
         FIG.  1 C  is a front drawing of another embodiment of the invention showing details of the connection between the knee and cylinder tube. 
         FIG.  2    is a front drawing of an embodiment of the invention showing the knee distractor components in position. 
         FIG.  3 A  is a perspective view of an ankle brace suitable for an embodiment of the invention. 
         FIG.  3 B  is another perspective view of an ankle brace suitable for an embodiment of the invention. 
         FIG.  4    is a perspective view of a knee brace suitable for of an embodiment of the invention. 
         FIG.  5    is graphical plot showing relationship between displacement and applied pressure of a cylinder of an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     In broad aspect, the invention is an apparatus and method for distraction (stretching and/or straightening) of injured or repaired knee joints. The apparatus comprises pneumatic or hydraulic cylinders that are designed to be disposed on either side of a leg with a knee to be treated. It is important that a cylinder be placed on each side of the leg to prevent equalize the pull on the knee joint. If only on one side it is likely that the knee would be pulled sidewise as well as downward. Cylinders are attached to a knee brace or other leg-holding device, secured above the knee joint, and attached to another device secured around the ankle of the leg. The leg-holding device and ankle device are not connected nor hinged together. When the cylinder is activated, (piston extended) the knee brace and ankle device are separated (moved apart) thus causing the knee joint to be straightened or slightly separated. 
     Referring to the drawings,  FIG.  1 A  illustrates a leg  201  with a knee  205  and upper knee brace  202  and lower knee brace  204 . Knee stretch cylinders  100  are attached on each side of a leg where connectors  118  are fitted with side straps on the braces  202 / 204 . In use, the lower section of the brace  204  is loosened to allow some small movement upward, and the upper section is secured. The lower section of the tube is removably attached to an ankle brace  212  by a suitable connector,  218 , (much like connector  118 ) and does not move during use.  FIGS.  1 B and  1 C  illustrate another embodiment of the system. In this embodiment, the piston extension  110  connects to a connection member  320  and  322  that has a slot (or other connection means) to receive a side brace of a flexion (means to set knee bend positions). It is not required that the connection  320  be able to permanently attach to brace side member  324  through  322  since the action is always upward. Rather, it is only necessary that the connection allow  110  to push brace member  324  upward in cylinder  180 . This embodiment allows the brace to be set for limited movement of the knee (as often required - as to keep the knee joint from fully straightening) and be pushed upward with the knee in the limited (as for example, slightly bent) position to, for example, separate the joint members without straightening the knee joint. Patents describing flexion set means include U.S. 5,672,152, US 5,827,208, and US 7235059, the relevant disclosures of which are incorporated herein by reference. Applicant is not aware of any known current apparatus that will allow this action of extension of a bent knee joint. Conduits (such as tubing)  114  extend from the knee stretch cylinder  100  (also shown as  101 ) (see  FIG.  2   ) to a Y connector  116  that is connected to the cylinder at  106  and to air pressure pump  216 . Member  214  is a pressure gauge preferably a digital gauge. The gauge allows for consistent, staged, and repeated use of the device. In use in a therapy protocol, the gauge will allow return to (or alteration) of a previous treatment stretch range.  FIG.  2    shows details of the knee stretch cylinder-100. The cylinder  100  comprises a straight, unitary, unhinged, hollow tube (such as a carbon or metal tube)  108  in which is disposed a straight unhinged unitary mechanical pneumatic cylinder  102  with an air connector  112  at the bottom and air hose  114  extending from the air hose connector  112  up through the open top of the tube. It is important the hollow tube and cylinder be configured so as not to bend in use so that the extension of the leg will be properly accomplished. The pneumatic cylinder is attached to the lower section of the tube at point  104 . It is preferred that the pneumatic cylinder be spring-loaded so that when no air pressure is applied, it will return to its starting position. The pneumatic (or hydraulic) cylinder has a piston  103  and a horizontally (at right angles to the length of the cylinder) arranged rod  110  that extends through a slot  120  in the tube  108 . The rod is connected to a brace connector  118 , a semicircular member that has a slot  119  into which fits a side arm of a knee brace. When the pneumatic cylinder is activated, the piston moves upward causing the rod and therefore the connector  118  to move upward putting tension between the upper brace and ankle brace, thus stretching the knee joint. In general, the slot  120  and therefore the travel of the rod upward will be about 1 to 4 inches, with 1 to-2 inches preferred. The air hoses  114  that feed the pneumatic cylinder are connected to flexible conduits  114  that are connected by a Y connector  116  to air pump  216 . 
     The upper knee brace is secure so that when the piston is extended, the space between the ankle brace  212  and the upper knee brace  202  is likewise extended putting tension on the knee joint and thereby stretching it. This accomplishes the desirable uncoupling or straightening of the joint - if the knee is bent, the action will tend to straighten it, and if the knee is straight, the action will uncouple or distract the joint. 
       FIG.  4    is an illustration of a suitable knee brace. There is a connection ( 118  to  518  on each side of the brace) attaching the cylinder tube (as  100  in  FIG.  1   ) to the vertical side straps,  502 , of the brace, which generally are only required to hold the strap in upward movement. Additionally, there are leg wrap bands  514  that can be latched via  510 ,  512  and  516  to tighten the brace  500  around the leg above and below the knee  205 . Hook and loop straps  520  and  504  are also used to secure the brace to the leg. Reaction braces from DonJoy™ can be adapted to be very suitable. In use, the knee brace will be loosened below the knee  205  to allow the more secure top section above the knee to be pushed upward by the cylinder action, thus extending the distance between the knee and ankle and ultimately distracting the knee joint. 
       FIGS.  3 A and  3 B  illustrate a suitable ankle brace,  400 . As with the knee braces, there will be a connection ( 218  to  418  on each side of the brace) attaching the cylinder tube (as  100  in  FIG.  1   ) to the sides of the brace. This ankle brace has a band  402  and side pads  406  and an underfoot pad  404 . Generally, it is only required to hold the brace in position to allow the ankle to be forced downward when the cylinder  100  is extended. In most ankle braces, it is preferred that the foot be placed in a shoe with the brace disposed inside the shoe, in order to ensure the connection to the ankle is secure. An ankle cuff can also be used in the same way as an ankle brace. Suitable ankle braces include T2 Multi-Sport Ankle Brace from Active nkle™. 
     Suitable cylinders include those available from Automation Direct (cylinders a07020sp –9/16 bore or a07020sp -- 7/16 bore), preferably those with a spring return. 
     Suitable hand air pumps include Silverline elite hand pump model 3mitmv8510 available from ToolTopia. 
     Method of Use 
     Generally, the apparatus will be fitted by an orthotic surgeon, physical therapist, or athletic/fitness trainer. The apparatus assembly will be fitted and attached to the knee and ankle braces. When properly adjusted, the assembly is tested and characteristics plotted by measuring the extension for a given pressure applied. The air pump (or hydraulic, if used) will be applied at various pressures - e.g. 2, 5, 8, 10 psi, and the displacement (and stretch) of the piston travel (distance from knee brace attachment to ankle brace attachment) measured. 
     
       
         
           
               
               
             
               
                 Characteristic Chart (Illustrative) 
               
               
                 Pressure, psi 
                 Displacement, cm 
               
             
            
               
                 2 
                 0.5 
               
               
                 4 
                 1.1 
               
               
                 6 
                 1.8 
               
               
                 8 
                 2.4 
               
               
                 10 
                 2.8 
               
               
                 12 
                 3.0 
               
               
                 14 
                 3.1 
               
            
           
         
       
     
     A characteristic curve such as illustrated in  FIG.  5    can be generated for each apparatus/used combination. Using the characteristic curve, a set of user protocol can be prescribed. The user can then use the assembly at any convenient place and time without needing to visit a therapy facility. 
     If a knee-lock brace is used (one that locks into a predetermined position), the practitioner, physical therapist, or athletic/fitness trainer will specify (and/or set) the brace knee position lock means in the desired treatment position of the knee joint. 
     In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. Therefore, the scope of the invention should be limited only by the appended claims.