To control pain after total knee replacement surgery a catheter (tubing) is sometimes inserted into an anatomic space containing nerves that provide sensation to parts of the knee. This space is called the adductor canal. The catheters often stop working before we remove them for unclear reasons. The investigators think this is because the catheters become dislodged from where it was meant to be. This could be due to repeated movements of the catheter tip brought on by patients contracting their leg muscles when they ambulate or perform physio. The investigators want to confirm this by measuring the distance from a fixed spot on the patient's thigh to the adductor canal using an ultrasound machine. The leg will be measured in various positions to simulate muscle movements. A significant change in the distance could possibly contribute to catheter dislodgement and result in catheter failure.
Study Type
OBSERVATIONAL
Enrollment
40
Ultrasound measurements will be made in 5 positions. The ultrasound probe will be measuring from a fixed external location of the thigh. The 5 positions include: external rotation, neutral, manual tissue external rotation, straight leg raise at 30 degrees and hip/knee flexion at 90 degrees.
University of British Columbia Hospital
Vancouver, British Columbia, Canada
Skin to Adductor Canal Distance Disparity
The largest distance disparity as measured from the 5 different leg positions
Time frame: Measurements will be made on the day of surgery, no other assessment or follow up needed
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