Method and apparatus for spinal surgery

Abstract

Spinal surgery is carried out under direct visualization through a relatively small opening formed in a patient's skin. Intervening tissue between the opening and the surgical site is displaced so as to form a keyhole channel therethrough. The channel is characterized in that it increases in width as it progresses from the opening to the surgical field. The use of the keyhole channel maximizes the surgeon's access to the surgical field while minimizing tissue trauma. Also disclosed are surgical retractors used to provide the channel.

1 . A surgical retractor for use in spinal surgery comprising: 
 a first and a second arm, each arm including a first end which defines a handle portion, and a second end having a retractor blade projecting therefrom, said arms being pivotally connected together at a connection point between their respective first and second ends;    wherein the retractor blade of the first arm and the retractor blade of the second arm each include a junction end at which said blade is permanently affixed to its respective arm, and a free end; and    wherein said arms and blades are configured and disposed so that when, in the use of the retractor, the arms are pivoted about said connection point, the free ends of the blades are always at least as far apart as said junction ends.    
     
     
         2 . The surgical retractor of  claim 1 , wherein when the arms are pivoted about the connection point in the use of the retractor, the free ends of the blades are always farther apart than are said junction ends.  
     
     
         3 . The retractor of  claim 1 , wherein at least one of said retractor blades includes a straight portion commencing at the junction end thereof.  
     
     
         4 . The retractor of  claim 3 , wherein said at least one blade also includes a curved portion commencing at the free end thereof.  
     
     
         5 . The retractor of  claim 1 , wherein the retractor blade of said first arm, and the retractor blade of said second arm each include a straight portion.  
     
     
         6 . The retractor of  claim 5 , wherein the straight portion of the blade of the first arm, and the straight portion of the blade of the second arm are parallel to one another.  
     
     
         7 . The retractor of  claim 5 , wherein the straight portion of the blade of the first arm, and the straight portion of the blade of the second arm are not parallel to one another.  
     
     
         8 . The retractor of  claim 1 , wherein the retractor blades each project from their respective arms at right angles to a longitudinal axis of said arm which extends from the first end thereof to the second end thereof.  
     
     
         9 . The retractor of  claim 1 , wherein at least one of said retractor blades is curved transverse to a longitudinal axis thereof which extends from the junction end thereof to the free end thereof.  
     
     
         10 . The retractor of  claim 1 , wherein both of said blades are curved transverse to a respective longitudinal axis which extends from a junction end thereof to a free end thereof.  
     
     
         11 . The retractor of  claim 1 , wherein at least one of said blades includes a groove therein configured to receive a portion of the other blade when the retractor is in a closed position.  
     
     
         12 . The retractor of  claim 1 , further including a locking assembly associated with said first and second arms for selectably immobilizing said arms relative to one another so that said arms will not pivot about said connection point.  
     
     
         13 . The retractor of  claim 1 , wherein said blades each have a width dimension measured transverse to a longitudinal axis thereof, which longitudinal axis extends from the free end thereof to the junction thereof, said width dimension being no greater than 20 millimeters.  
     
     
         14 . The retractor of  claim 13 , wherein said width dimension is no greater than 15 millimeters.  
     
     
         15 . The retractor of  claim 1 , further including an extension portion configured to be retainably engaged by the free end of one of said retractor blades.  
     
     
         16 . A method for performing a spinal surgery, said method comprising the steps of: 
 forming an opening through the skin of a patient, said opening having a maximum dimension of no more than 20 millimeters, said opening being separated from a surgical field by intervening tissue;    displacing said intervening tissue between said opening and said surgical field so as to form a keyhole channel therethrough, said keyhole channel being characterized in that it increases in width as it progresses from said opening to said surgical field; whereby the cross-sectional area of said surgical field exposed by said channel is greater than the cross-sectional area of said opening; and    performing a surgical procedure at said surgical field.    
     
     
         17 . The method of  claim 16 , wherein the step of performing a surgical procedure comprises performing said surgical procedure under direct visualization.  
     
     
         18 . The method of  claim 16 , wherein the step of displacing said tissue comprises: 
 providing a surgical retractor having a pair of separable, tissue engaging blades;    providing a passage through said intervening tissue;    inserting the blades of said retractor into said passage; and    separating the blades of said retractor whereby said retractor displaces said intervening tissue so as to form said keyhole channel.    
     
     
         19 . The method of  claim 16 , wherein the step of forming said passage comprises inserting a dilator into said intervening tissue, said dilator being operable to form said passage.  
     
     
         20 . The method of  claim 19 , wherein said dilator comprises a series of dilator mandrels, each having a different diameter.  
     
     
         21 . The method of  claim 19 , wherein said dilator comprises an expansible member.  
     
     
         22 . The method of  claim 19 , wherein said dilator comprises a cylindrical member having a C-shaped cross section.  
     
     
         23 . The method of  claim 19 , wherein the blades of said retractor are inserted into said passage before said dilator is withdrawn therefrom.  
     
     
         24 . The method of  claim 16 , wherein said procedure is a discectomy.  
     
     
         25 . The method of  claim 15 , wherein said procedure is a laminectomy or discectomy carried out via microsurgical techniques.  
     
     
         26 . The method of  claim 16 , wherein said retractor comprises a first and a second arm, each arm including a first end which defines a handle portion, and a second end having one of said retractor blades projecting therefrom, said arms being pivotally connected together at a connection point between their respective first and second ends; wherein the retractor blade of the first arm and the retractor blade of the second arm each include a junction end at which said blade is permanently affixed to its respective arm, and a free end; and wherein, said arms and blades are configured and disposed so that when, in the use of the retractor, the arms are pivoted about said connection point, the free ends of the blades are always at least as far apart as said junction ends.