Angled rotary tissue cutting instrument and method of fabricating the same

Abstract

The present invention is generally characterized in an angled rotary tissue cutting instrument including an outer blade assembly, having a rigid tubular member with proximal and distal portions connected by a bead, and an inner blade assembly rotatably disposed within the outer blade assembly and including a tubular drive shaft at a proximal end, a cutting tip at a distal end, and a flexible coupling disposed between the drive shaft and the cutting tip. The drive shaft and cutting tip include neck portions which are disposed telescopically within proximal and distal ends of the coupling. The flexible coupling is formed of a flexible polymeric material, and each of the neck portions includes a lateral opening defining a predetermined flow path for the polymeric material during fabrication so that the flexible polymeric coupling includes flow portions extending into the openings in the neck portions of the drive shaft and the cutting tip to form permanent, interlocking mechanical joints therewith capable of receiving and transmitting torque.

What is claimed is:  
     
       1. An angled rotary tissue cutting instrument comprising an outer blade assembly including a rigid tubular member having proximal and distal portions connected by a bend; and 
       an inner blade assembly rotatably disposed within said outer blade assembly and including a tubular drive shaft at a proximal end, a cutting tip at a distal end, and a flexible coupling disposed between said drive shaft and said cutting tip within said bend in said outer blade assembly;  
       said flexible coupling including a hollow tubular member formed of a flexible polymeric material and having proximal and distal ends;  
       said drive shaft and cutting tip including neck portions disposed telescopically within said respective proximal and distal ends of said flexible polymeric coupling, each of said neck portions including a lateral opening defining a predetermined flow path for said polymeric material during fabrication; and  
       said flexible polymeric coupling including inwardly protruding portions molded in place within said openings in said neck portions of said drive shaft and said cutting tip to form permanent, interlocking mechanical joints capable of receiving and transmitting torque.  
     
     
       2. An angled rotary tissue cutting instrument as recited in  claim 1  and further comprising a pair of bands formed of shrink wrap tubing disposed around said flexible polymeric coupling adjacent said respective proximal and distal ends of said coupling to provide compressing directing the flow of polymeric material into said openings in said neck portions during fabrication and to provide a pair of lubricious bearing surfaces at opposite ends of said bend during operation. 
     
     
       3. An angled rotary tissue cutting instrument as recited in  claim 1  wherein said opening in at least one of said neck portions includes a slot. 
     
     
       4. An angled rotary tissue cutting instrument as recited in  claim 3  wherein said slot is defined by laterally opposed edges angled away from one another in the direction of a curved edge connecting terminal ends of said angled edges. 
     
     
       5. An angled rotary tissue cutting instrument as recited in  claim 3  wherein said slot is defined by laterally opposed edges angled away from one another in the direction of a straight edge transversely connecting terminal ends of said angled edges. 
     
     
       6. An angled rotary tissue cutting instrument as recited in  claim 1  wherein said opening in at least one of said neck portions includes a first slot oriented parallel to a longitudinal axis of said neck portion and a second slot oriented transverse to said first slot. 
     
     
       7. An angled rotary tissue cutting instrument as recited in  claim 1  wherein said opening in at least one of said neck portions includes a pair of spaced through-holes. 
     
     
       8. An angled rotary tissue cutting instrument as recited in  claim 1  wherein said flexible coupling further includes a plurality of wires embedded within said polymeric tubular member therein as reinforcement. 
     
     
       9. An angled rotary tissue cutting instrument as recited in  claim 8  wherein said wires are arranged in a plurality of layers wound in opposite directions to define a mesh-like reinforcing structure within said polymeric coupling. 
     
     
       10. An angled rotary tissue cutting instrument as recited in  claim 9  wherein each layer includes a plurality of circumferentially spaced, helically intertwined wires oriented at acute angles relative to the longitudinal axis of said polymeric coupling. 
     
     
       11. An angled rotary tissue cutting instrument as recited in  claim 10  wherein said wires are oriented at angles of about 45° relative to said longitudinal axis of said polymeric coupling to transmit torque without substantial preloading. 
     
     
       12. An angled rotary tissue cutting instrument as recited in  claim 1  wherein said distal portion of said outer blade assembly is oriented at an angle of between about 35° and about 60° relative to the longitudinal axis of said proximal portion with a bend radius of no more than about 1.5 inches. 
     
     
       13. An angled rotary tissue cutting instrument as recited in  claim 12  wherein said bend is located adjacent a distal end of said outer blade. 
     
     
       14. An angled rotary tissue cutting instrument as recited in  claim 12  wherein said bend is located adjacent a proximal end of said outer blade. 
     
     
       15. An angled rotary tissue cutting instrument as recited in  claim 12  wherein said distal portion of said outer blade defines a cutting window facing outwardly of a center of curvature of said bend. 
     
     
       16. An angled rotary tissue cutting instrument as recited in  claim 1  wherein said outer tubular member includes a plurality of bends. 
     
     
       17. An angled rotary tissue cutting instrument as recited in  claim 16  wherein said outer tubular member includes a pair of longitudinally spaced bends and an intermediate portion of straight configuration extending between said longitudinally spaced bends. 
     
     
       18. An angled rotary tissue cutting instrument as recited in  claim 17  wherein said inner blade assembly includes a pair of flexible couplings disposed in said longitudinally spaced bends and a rigid connecting tube disposed between said flexible couplings. 
     
     
       19. An angled rotary tissue cutting instrument as recited in  claim 18  wherein said intermediate portion is oriented at an angle of between about 40° and about 50° in a first direction relative to a longitudinal axis of said proximal portion and said distal portion is oriented at an angel of between about 10° and about 20° in a second, opposite direction relative to a longitudinal axis of said intermediate portion. 
     
     
       20. An angled rotary tissue cutting instrument as recited in  claim 19  wherein said said straight portion is oriented at an angle of about 45° relative to a longitudinal axis of said proximal portion and said distal portion is oriented at an angle of about 15° relative to a longitudinal axis of said straight portion. 
     
     
       21. An angled rotary tissue cutting instrument as recited in  claim 18  wherein said connecting tube includes a neck portion at each end disposed telescopically within respective ends of said flexible couplings, each of said neck portions including a lateral opening defining a predetermined flow path for said polymeric coupling material during fabrication. 
     
     
       22. A method of fabricating an angled rotary tissue cutting instrument comprising the steps of 
       positioning a neck portion at the proximal end of a cutting tip in the distal end of a flexible polymeric coupling of tubular configuration;  
       positioning a neck portion at the distal end of a drive shaft in the proximal end of the flexible polymeric coupling;  
       placing a first band of shrink tubing over a proximal end of the flexible polymeric coupling;  
       placing a second band of shrink tubing over a distal end of the flexible polymeric coupling;  
       heating the shrink tubing and the flexible polymeric coupling to cause the polymeric coupling to flow and the shrink tubing to contract around the polymeric coupling such that the polymeric material flows along predetermined flow paths defined by lateral openings in the neck portions of the drive shaft and cutting tip; and  
       cooling the shrink tubing and the flexible polymeric coupling so that flowed portions of the polymeric coupling harden within the openings in the neck portions to form permanent, interlocking mechanical joints therewith capable of receiving and transmitting torque as an integral inner blade assembly.  
     
     
       23. A method of fabricating an angled rotary tissue cutting instrument as recited in  claim 22  and further comprising, prior to said heating step, the step of placing a mandrel within the drive shaft and the cutting tip to prevent the polymeric material of the flexible coupling from flowing into the lumen defined by the drive shaft and the cutting tip. 
     
     
       24. A method of fabricating an angled rotary tissue cutting instrument as recited in  claim 22  and further comprising, after said heating step, the step of removing the shrink tubing from the polymeric coupling. 
     
     
       25. A method of fabricating an angled rotary tissue cutting instrument as recited in  claim 22  and further comprising, after said cooling step, the step of inserting the inner blade assembly within an outer blade assembly including a rigid tubular member having proximal and distal portions connected by a bend. 
     
     
       26. A rotary tissue cutting instrument forming a laryngeal blade comprising 
       
         a rigid outer tubular member having a hub, a proximal portion of straight configuration having a longitudinal axis and extending distally from said hub to a proximal bend curving in a first direction, a straight intermediate portion extending distally at an angle to said longitudinal axis of said proximal portion from said proximal bend to a distal bend curving in a second direction opposite to said first direction and a straight distal portion extending distally from said distal bend to a distal end having an opening therein, said proximal portion having a length between said hub and said proximal bend, said intermediate portion having a length between said proximal bend and said distal bend, said distal portion having a length between said distal bend and said distal end and said length of said intermediate portion being greater than said length of said proximal portion and being greater than said length of said distal portion;  
       
       
         an inner member rotatably disposed in said outer tubular member and having a proximal end for mounting to a powered handpiece and a distal cutting tip disposed adjacent said opening in said distal end of said outer tubular member, said inner member being flexible adjacent said distal and proximal bends; and  
       
       
         a suction passage extending along said inner member to permit aspiration of cut tissue. 
       
     
     
       27. A rotary tissue cutting instrument as recited in  claim 26  wherein said length of said proximal portion is about the same as said length of said distal portion. 
     
     
       28. A rotary tissue cutting instrument as recited in  claim 27  wherein said length of said proximal and distal portions is about  0 . 5  inch and said length of said intermediate portion is between  8  and  10  inches. 
     
     
       29. A rotary tissue cutting instrument as recited in  claim 26  wherein said intermediate portion has a longitudinal axis disposed at an angle ranging between about  40 ° and about  50 ° relative to said longitudinal axis of said proximal portion and said distal portion is disposed at an angle of about  20 ° or less relative to said longitudinal axis of said intermediate portion. 
     
     
       30. A rotary tissue cutting instrument as recited in  claim 29  wherein said angle of said intermediate portion is about  45 ° and said angle of said distal portion is about  15 °. 
     
     
       31. A rotary tissue cutting instrument as recited in  claim 29  wherein said proximal bend has a radius of curvature of about  1 . 5  inches and said distal bend has a radius of curvature of about  0 . 875  inch. 
     
     
       32. A rotary cutting instrument as recited in  claim 26  wherein said inner member is tubular and said suction passage extends through said inner member. 
     
     
       33. A rotary cutting instrument as recited in  claim 32  wherein said inner member includes first and second flexible portions extending through said proximal bend and said distal bend, respectively. 
     
     
       34. A rotary cutting instrument as recited in claims  32  wherein said inner member includes a drive shaft and a flexible coupling connecting said drive shaft with said distal cutting tip.