Method and apparatus for deploying a shape memory polymer

Abstract

Methods and apparatus described herein may utilize activation of an SMP material to install medical devices with respect to a surgical site. Activation of the SMP material may be performed with the use of a triggering force and/or a constraint applied to the SMP material. Activation using a triggering force and/or a constraint may be used to create varied activation rates in an SMP material and may be combined with temperature or other activation stimuli to create the varied activation rates.

1 . A method comprising:
 (A) inserting into a surgical site a medical device including a shape memory polymer portion having a stored strain;   (B) raising the temperature of the shape memory polymer portion to a first activation temperature, thereby activating the shape memory polymer portion at a first activation rate; and   (C) applying a trigger force to the shape memory polymer portion, thereby changing the activation rate of the shape memory polymer portion from the first activation rate to a second activation rate.   
     
     
         2 . The method of  claim 1 , further comprising:
 while applying the trigger force, changing the temperature of the shape memory polymer portion to a second activation temperature, thereby further changing the activation rate of the shape memory polymer portion to a third activation rate.   
     
     
         3 . The method of  claim 2 , wherein the third activation rate is different from the first activation rate and different from the second activation rate. 
     
     
         4 . The method of  claim 2 , wherein the third activation rate is different from a fourth activation rate equal to a test activation rate of the shape memory polymer portion at the second activation temperature in an unconstrained environment. 
     
     
         5 . The method of  claim 1 , wherein raising the temperature of the shape memory polymer portion is performed by contacting the medical device with the surgical site. 
     
     
         6 . The method of  claim 1 , further comprising:
 (A) determining that a desired portion of the stored strain has been recovered by the shape memory polymer portion; and   (B) in response to determining that the desired portion of the stored strain has been recovered, reducing the trigger force applied to the shape memory polymer portion.   
     
     
         7 . The method of  claim 1 , further comprising:
 comparing the first activation rate with a threshold activation rate.   
     
     
         8 . The method of  claim 7 , wherein applying the trigger force is performed if, based on the comparing step, the first activation rate is below the threshold activation rate. 
     
     
         9 . The method of  claim 1 , wherein changing the activation rate further includes increasing the activation rate of the shape memory polymer from the first activation rate to the second activation rate. 
     
     
         10 . A method comprising:
 (A) straining a shape memory polymer with a deforming force from an unconstrained shape to a pre-implantation shape;
 (i) wherein the shape memory polymer forms at least a portion of a medical device; 
   (B) inserting the medical device into a surgical site while the shape memory polymer is in the pre-implantation shape;   (C) activating the shape memory polymer via applying a trigger force to the shape memory polymer; and   (D) reducing the trigger force after the shape memory polymer has achieved a post-implantation shape different from the pre-implantation shape.   
     
     
         11 . The method of  claim 10 , further comprising:
 raising the temperature of the shape memory polymer.   
     
     
         12 . The method of  claim 11 , wherein raising the temperature of the shape memory polymer is performed by contacting the medical device with the surgical site. 
     
     
         13 . The method of  claim 10 , further comprising:
 determining that the shape memory polymer is activated at a first activation rate.   
     
     
         14 . The method of  claim 13 , further comprising:
 changing the trigger force based on the determining step.   
     
     
         15 . The method of  claim 10 , wherein applying the trigger force thereby changes an activation rate of the shape memory polymer portion from a first activation rate to a second activation rate. 
     
     
         16 . The method of  claim 10 , wherein a maximum magnitude of the trigger force is less than a maximum magnitude of the deforming force. 
     
     
         17 . A method comprising:
 (A) inserting a medical device into a surgical site;
 (i) wherein the medical device contains a shape memory polymer portion with a stored strain; 
 (ii) wherein the medical device interfaces with a first constraint; 
   (B) activating the shape memory polymer portion via applying a second constraint to the medical device;
 (i) wherein the second constraint is different from the first constraint; and 
 (ii) wherein the second constraint is adapted to apply a force to the shape memory polymer portion in an opposing direction to the stored strain. 
   
     
     
         18 . The method of  claim 17 , further comprising:
 raising the temperature of the shape memory polymer portion.   
     
     
         19 . The method of  claim 17 , further comprising:
 removing the first constraint from the medical device before applying the second constraint.   
     
     
         20 . The method of  claim 17 , further comprising:
 applying a third constraint to the medical device, wherein the third constraint is different from the second constraint.