Lock and release mechanism for a sternal clamp

Abstract

An engagement mechanism for a sternal clamp, the mechanism allowing for an open status where the clamp may be lengthened or shortened, a closing status where the clamp may only be shortened, and a locked status where the clamp cannot be lengthened or shortened.

1 . A sternal clamp device comprising: 
 a first clamp member and a second clamp member slidingly engaged such that the overall length of said sternal clamp device may be shortened or lengthened by relative movement of said first and second clamp members, each said clamp member comprising at least one leg members to abut the sides of a sternum;    engagement means controlling relative movement of said first and second clamp members; and    status control means to select one of three operating statuses for said sternal clamp device, said operating statuses consisting of an open status, a closing status and a locked status;    whereby in said open status said sternal clamp device may be lengthened or shortened, in said closing status said sternal clamp device may be shortened but not lengthened, and in said locked status said sternal clamp may be neither lengthened nor shortened.    
   
   
       2 . The device of  claim 1 , wherein said engagement means comprises a biased engagement arm having a plurality of teeth, said engagement arm disposed on said first clamp member, and a ratchet bar having a plurality of teeth, said ratchet bar disposed on said first clamp member, whereby said engagement arm teeth and said ratchet bar teeth are able to engage with each other.  
   
   
       3 . The device of  claim 2 , wherein said status control means comprises a cam opening disposed in said engagement arm and a rotatable cam follower positioned within said cam opening, whereby selection of said operating status and freedom of movement of said engagement arm is determined by the position of said cam follower.  
   
   
       4 . The device of  claim 3 , wherein said engagement arm is pivotally mounted, such that in said locked status said engagement arm is precluded from pivoting away from said ratchet bar, in said closing status said engagement arm can pivot sufficient distance from said ratchet bar to allow said engagement arm teeth and said ratchet bar teeth to slide over each other, and in said open status said engagement arm is held in a fixed position away from said ratchet bar such that said engagement arm teeth and said ratchet bar teeth are not in contact.  
   
   
       5 . The device of  claim 3 , wherein said status control means further comprises a post member retaining said cam follower, a head member disposed on said post member and a slot disposed in said head member, said post member being rotatably mounted in said second clamp member.  
   
   
       6 . The device of  claim 2 , wherein said engagement arm teeth each have an inclined side and an abutment side, said abutment sides being more perpendicularly oriented than said inclined sides, and wherein said ratchet bar teeth each have an inclined side and an abutment side, said abutment sides being more perpendicularly oriented than said inclined sides, whereby the inclined sides of said engagement arm teeth and said ratchet bar teeth face each other and the abutment sides of said engagement arm teeth and said ratchet bar teeth face each other.  
   
   
       7 . A sternal clamp device comprising: 
 a first clamp member and a second clamp member to engage the sides of a sternum;    sliding means joining said first and second clamp members together whereby said sternal clamp can be lengthened or shortened;    engagement means to restrict relative motion of said first and second clamp members;    status control means to control said engagement means, said status control means being operable in a locked status, a closing status and an open status;    whereby said status control means disposed in said locked status precludes relative movement of said first and said second clamp members, disposed in said closing status allows relative movement of said first and said second clamp members together so as to shorten said sternal clamp but precludes relative movement of said first and second clamp members apart so as to lengthen said sternal clamp, and disposed in said open status allows relative movement of said first and said second clamp members both together and apart.    
   
   
       8 . The device of  claim 7 , wherein said engagement means comprises a biased engagement arm having a plurality of teeth, said engagement arm disposed on said first clamp member, and a ratchet bar having a plurality of teeth, said ratchet bar disposed on said second clamp member, whereby said engagement arm teeth and said ratchet bar teeth are able to engage with each other.  
   
   
       9 . The device of  claim 8 , wherein said status control means comprises a cam opening disposed in said engagement arm and a rotatable cam follower positioned within said cam opening, whereby selection of said operating status and freedom of movement of said engagement arm is determined by the position of said cam follower.  
   
   
       10 . The device of  claim 9 , wherein said engagement arm is pivotally mounted, such that in said locked status said engagement arm is precluded from pivoting away from said ratchet bar, in said closing status said engagement arm can pivot sufficient distance from said ratchet bar to allow said engagement arm teeth and said ratchet bar teeth to slide over each other, and in said open status said engagement arm is held in a fixed position away from said ratchet bar such that said engagement arm teeth and said ratchet bar teeth are not in contact.  
   
   
       11 . The device of  claim 9 , wherein said status control means further comprises a post member retaining said cam follower, a head member disposed on said post member and a slot disposed in said head member, said post member being rotatably mounted in said second clamp member.  
   
   
       12 . The device of  claim 8 , wherein said engagement arm teeth each have an inclined side and an abutment side, said abutment sides being more perpendicularly oriented than said inclined sides, and wherein said ratchet bar teeth each have an inclined side and an abutment side, said abutment sides being more perpendicularly oriented than said inclined sides, whereby the inclined sides of said engagement arm teeth and said ratchet bar teeth face each other and the abutment sides of said engagement arm teeth and said ratchet bar teeth face each other.  
   
   
       13 . A sternal clamp device for securing two severed halves of a sternum in abutting relation, said device comprising: 
 a first clamp member comprising a main body and at least one leg member;    a second clamp member comprising a main body and at least one leg member, said second clamp member joined to said first clamp member in a sliding manner whereby said sternal clamp device may be lengthened by relative movement of said first and second clamp members away from each other and whereby said sternal clamp device may be shortened by relative movement of said first and second clamp members toward each other, such that said sternal clamp device is lengthened and positioned on said sternal halves such that said sternal halves are between said leg members of said first and second clamp members, and said sternal clamp device is shortened to force said sternal halves together;    engagement means to control relative movement of said first and said second clamp members;    status control means to control said engagement means, whereby said engagement means is set in one of three operating statuses, a locked status wherein relative movement of said first and said second clamp members is precluded, a closing status wherein relative movement of said first and said second clamp members toward each other is allowed but relative movement away from each other is precluded, and an open status wherein relative movement of said first and said second clamp members in either direction is allowed.    
   
   
       14 . The device of  claim 13 , wherein said engagement means comprises a biased engagement arm having a plurality of teeth, said engagement arm disposed on said first clamp member, and a ratchet bar having a plurality of teeth, said ratchet bar disposed on said second clamp member, whereby said engagement arm teeth and said ratchet bar teeth are able to engage with each other.  
   
   
       15 . The device of  claim 14 , wherein said status control means comprises a cam opening disposed in said engagement arm and a rotatable cam follower positioned within said cam opening, whereby selection of said operating status and freedom of movement of said engagement arm is determined by the position of said cam follower.  
   
   
       16 . The device of  claim 15 , wherein said engagement arm is pivotally mounted, such that in said locked status said engagement arm is precluded from pivoting away from said ratchet bar, in said closing status said engagement arm can pivot sufficient distance from said ratchet bar to allow said engagement arm teeth and said ratchet bar teeth to slide over each other, and in said open status said engagement arm is held in a fixed position away from said ratchet bar such that said engagement arm teeth and said ratchet bar teeth are not in contact.  
   
   
       17 . The device of  claim 15 , wherein said status control means further comprises a post member retaining said cam follower, a head member disposed on said post member and a slot disposed in said head member, said post member being rotatably mounted in said second clamp member.  
   
   
       18 . The device of  claim 14 , wherein said engagement arm teeth each have an inclined side and an abutment side, said abutment sides being more perpendicularly oriented than said inclined sides, and wherein said ratchet bar teeth each have an inclined side and an abutment side, said abutment sides being more perpendicularly oriented than said inclined sides, whereby the inclined sides of said engagement arm teeth and said ratchet bar teeth face each other and the abutment sides of said engagement arm teeth and said ratchet bar teeth face each other.