Soft tissue balancing in robotic knee surgery

Abstract

A system and method may be used to evaluate soft tissue. A knee arthroplasty soft tissue evaluation may use an adjustable spacer, such as varying sized physical spacers or an inflatable bladder, along with a sensor to measure force, pressure, gap distance, or the like during a range of motion test. A method may include maintaining an equal pressure or gap distance for a medial component and a lateral component of an adjustable spacer during a range of motion test. Information, including, for example a maximum or minimum gap distance or pressure may be determined during the range of motion test. The determined information may be output for display or used to update a surgical plan.

What is claimed is: 
     
         1 . A surgical device for evaluating soft tissue during a surgical procedure comprising:
 a pump to:
 inflate a first adjustable component of an adjustable spacer to separate a femur and a tibia of a knee on a medial side of a patient; 
 inflate a second adjustable component of the adjustable spacer to separate the femur and the tibia of the knee on a lateral side of the patient, the second adjustable component independently adjustable to the first adjustable component; and 
 during a range of motion test, maintain an equal pressure in the first adjustable component and the second adjustable component by allowing a medial gap distance between the femur and the tibia caused by the first adjustable component or a lateral gap distance between the femur and the tibia the second adjustable component to change; and 
   a processor to:
 determine a maximum gap distance during the range of motion test; and 
 output the maximum gap distance for display on a user interface. 
   
     
     
         2 . The surgical device of  claim 1 , wherein the pump is further to decrease the equal pressure during a repeated range of motion test. 
     
     
         3 . The surgical device of  claim 1 , wherein the processor is to use a preoperative plan to determine the equal pressure. 
     
     
         4 . The surgical device of  claim 3 , wherein the processor is further to adjust the preoperative plan based on the maximum gap distance. 
     
     
         5 . The surgical device of  claim 1 , wherein the range of motion test occurs after a tibial cut during a knee arthroplasty. 
     
     
         6 . The surgical device of  claim 1 , wherein the processor is further to determine an implant based on a maximum medial gap distance and a maximum lateral gap distance, the implant having a first height for the medial side and a second height different from the first height for the lateral side. 
     
     
         7 . The surgical device of  claim 1 , wherein to determine the maximum gap distance, the processor is to use optical tracking of the femur and the tibia. 
     
     
         8 . The surgical device of  claim 1 , wherein the surgical device is a robotic surgical device, wherein the processor operates a robotic controller, wherein the pump is controlled by the processor, and wherein the robotic surgical device includes a display, the display configured to present the user interface including the maximum gap distance. 
     
     
         9 . A surgical device for evaluating soft tissue during a surgical procedure comprising:
 a pump to:
 inflate a first adjustable component of an adjustable spacer to separate a femur and a tibia of a knee on a medial side of a patient; 
 inflate a second adjustable component of the adjustable spacer to separate the femur and the tibia of the knee on a lateral side of the patient, the second adjustable component independently adjustable to the first adjustable component; 
 during a range of motion test, maintain an equal gap distance between a medial gap of the knee caused by the first adjustable component and a lateral gap of the knee caused by the second adjustable component by increasing or decreasing pressure in the first adjustable component or the second adjustable component; 
   a processor to:
 determine a maximum pressure during the range of motion test; and 
 output the maximum pressure for display on a user interface. 
   
     
     
         10 . The surgical device of  claim 9 , wherein is further to decrease the equal gap distance and perform the range of motion test again. 
     
     
         11 . The surgical device of  claim 9 , wherein the processor is to use a preoperative plan used to determine the equal gap distance and adjust the preoperative plan based on the maximum pressure. 
     
     
         12 . The surgical device of  claim 9 , wherein the range of motion test occurs after a tibial cut during a knee arthroplasty. 
     
     
         13 . The surgical device of  claim 9 , wherein the processor is further to determine an implant based on a maximum medial pressure and a maximum lateral pressure, the implant having a first height for the medial side and a second height different from the first height for the lateral side. 
     
     
         14 . The surgical device of  claim 9 , wherein to determine the maximum pressure, the processor is to use optical tracking of the femur and the tibia. 
     
     
         15 . The surgical device of  claim 9 , wherein the surgical device is a robotic surgical device, wherein the processor operates a robotic controller, wherein the pump is controlled by the processor, and wherein the robotic surgical device includes a display, the display configured to present the user interface including the maximum gap distance. 
     
     
         16 . A method comprising:
 inserting a trial between a femur and a tibia of a knee, the trial including a medial spacer of a first height and a lateral spacer of a second height differing from the first height;   using a pressure sensor device, measuring pressure on a medial side of the knee and a lateral side of the knee throughout a range of motion test with the trial in place;   determining a maximum pressure during the range of motion test; and   outputting the maximum pressure for display on a user interface.   
     
     
         17 . The method of  claim 16 , further comprising decreasing the first height or the second height by replacing the medial spacer or the lateral spacer and performing the range of motion test again. 
     
     
         18 . The method of  claim 16 , further comprising using a preoperative plan to determine the first height and the second height, and adjusting the preoperative plan based on the maximum pressure. 
     
     
         19 . The method of  claim 16 , further comprising performing the range of motion test after a tibial cut during a knee arthroplasty. 
     
     
         20 . The method of  claim 16 , further comprising determining an implant based on a maximum medial pressure and a maximum lateral pressure, the implant having a first height for the medial side and a second height different from the first height for the lateral side.