Methods and apparatus for annealing sutures

Abstract

The present invention is related to methods and apparatus that can enhance the security of a suture knot by annealing a portion of the suture knot. Such a suture knot is less likely to fail by slippage. Advantageously, the methods and apparatus can operate in a liquid environment, such as the inside of a body. Conventional knots made from monofilament sutures exhibit an unfortunate tendency to slip or untie. A surgeon can tie a conventional monofilament suture using standard knot tying techniques and anneal the suture. The annealing can fuse the tails of the suture together, thereby preventing failure by slippage. In one embodiment, the annealing textures the surface of the monofilament tails, thereby increasing friction and resistance to slippage. In another embodiment, the annealing is applied to the last throw in the knot.

What is claimed is:  
     
         1 . A method of enhancing the security of a synthetic suture knot, the method comprising: 
 tying the suture to form the knot;    placing a first length of a first limb of the knot in contact with a second length of a second limb of the knot;    momentarily applying heat to at least a first portion of the first limb and a second portion of the second limb while maintaining the contact between the first and the second lengths, wherein the applied heat is sufficient to fuse the first and the second portions into a fused portion; and    trimming the first limb and the second limb distal to the fused portion.    
     
     
         2 . The method as defined in  claim 1 , wherein the suture comprises monofilament suture.  
     
     
         3 . The method as defined in  claim 1 , wherein the fused portion is approximately 3 millimeters long.  
     
     
         4 . The method as defined in  claim 1 , wherein the momentary application of heat and the trimming of the limbs occur in a liquid environment.  
     
     
         5 . The method as defined in  claim 4 , further comprising insulating the liquid environment from the applied heat to reduce heating of the liquid environment.  
     
     
         6 . The method as defined in  claim 4 , wherein the liquid environment is inside a human body.  
     
     
         7 . A method of enhancing the security of a synthetic suture knot, the method comprising: 
 tying the suture to form the knot;    momentarily applying heat to a first area of a first limb of the knot in a liquid environment;    momentarily applying heat to a second area of a second limb of the knot in the liquid environment;    cutting the first limb such that a first short length of the first limb remains attached to the knot, where the first short limb includes at least a first portion of the first area; and    cutting the second limb such that a second short length of the second limb remains attached to the knot, where the second short limb includes at least a second portion of the second area.    
     
     
         8 . The method as defined in  claim 7 , wherein the heat applied to the first and the second areas derive from a common instrument.  
     
     
         9 . The method as defined in  claim 7 , wherein the heat is applied to the first limb and to the second limb such that a texturing of the surface of the first limb and the second limb occurs.  
     
     
         10 . The method as defined in  claim 7 , wherein the short length is approximately 3 millimeters.  
     
     
         11 . The method as defined in  claim 7 , further comprising applying heat to a last throw of the knot such that a first portion of the last throw bonds to a second portion of the last throw.  
     
     
         12 . A method of enhancing the security of a synthetic suture knot, the method comprising: 
 tying the suture to form the knot;    momentarily applying heat to an area of a limb of the knot in a liquid environment; and    cutting the limb such that a short length of the limb remains attached to the knot, where the short length includes at least a portion of the area.    
     
     
         13 . A method of enhancing the security of a suture knot, the method comprising: 
 tying the suture to form the knot;    momentarily applying heat to a last throw of the knot such that a first portion of the suture fuses to a second portion of the suture; and    cutting a first limb and a second limb.    
     
     
         14 . An apparatus that enhances the security of a synthetic suture knot, the apparatus comprising: 
 means for placing a first length of a first limb of the knot in contact with a second length of a second limb of the knot;    means for momentarily applying heat to at least a first portion of the first limb and a second portion of the second limb while maintaining the contact between the first and the second lengths, wherein the applied heat is sufficient to fuse the first and the second portions into a fused portion; and    means for cutting the first limb and the second limb distal to the fused portion.    
     
     
         15 . An annealing device to enhance the security of a synthetic knot tied in a liquid environment, the annealing device comprising: 
 a shaft having a proximal end and a distal end, wherein the distal end of the shaft is adapted to slide into a hollow tube;    a tip coupled to the distal end of the shaft, where the tip is insulated to decrease an amount of heat transferred from the tip to the liquid environment;    a channel within the tip having a first opening and a second opening, wherein the channel is adapted to allow the passage of a pair of suture tails from the knot; and    a heating element coupled to the channel, wherein the heating element heats the channel such that the temperature of the suture tails within the channel is increased.    
     
     
         16 . The annealing device as defined in  claim 15 , wherein the channel is approximately 3 millimeters long.  
     
     
         17 . The annealing device as defined in  claim 15 , wherein the heating element is adapted to heat the suture tails in the channel such that the suture tails fuse together.  
     
     
         18 . The annealing device as defined in  claim 15 , further comprising a temperature sensor to provide an indication of the temperature of the channel.  
     
     
         19 . The annealing device as defined in  claim 15 , further comprising an electrical insulator disposed between the heating element and the channel.  
     
     
         20 . The annealing device as defined in  claim 15 , further comprising a power source coupled to the heating element, where the power source is adapted to control the temperature of the channel.  
     
     
         21 . The annealing device as defined in  claim 15 , wherein the second opening of the channel is delimited by the outer circumference of the tip, further comprising a cutter having a distal end and a proximal end, where the cutter is slidably coupled to the annealing device such that when the cutter advances towards the second opening, a cutting edge coupled to a distal end of the cutter trims the suture tails that exit out of the second opening.  
     
     
         22 . The annealing device as defined in  claim 15 , wherein the second opening of the channel is internal to the shaft such that suture tails fed through the channel are guided to an interior of the shaft.  
     
     
         23 . An annealing device to enhance the security of a synthetic knot tied in a liquid environment, the annealing device comprising: 
 a shaft having a proximal end and a distal end, wherein the distal end of the shaft is adapted to slide into a hollow tube;    a tip coupled to the distal end of the shaft, where the tip is insulated to decrease an amount of heat transferred from the tip to the liquid environment;    a heating surface within the tip that is adapted to contact an uppermost throw of the suture knot; and    a heating element coupled to the heating surface, where the heating element heats the heating surface such that the suture throws in contact with the heating surface at least partially fuse.    
     
     
         24 . The annealing device as defined in  claim 23 , further comprising a temperature sensor to provide an indication of the temperature of the heating surface.  
     
     
         25 . The annealing device as defined in  claim 23 , further comprising electrical insulation disposed between the heating element and the heating surface.  
     
     
         26 . The annealing device as defined in  claim 23 , wherein a portion of the annealing device adapted to immerse in the liquid environment is substantially watertight.  
     
     
         27 . A suture knot produced in accordance with the method defined by  claim 1 .  
     
     
         28 . A suture knot produced in accordance with the method defined by  claim 7 .  
     
     
         29 . A suture knot produced in accordance with the method defined by  claim 12.