A 68-year-old man with BMI of 39 and a right valgus knee deformity of 15 degrees is scheduled for right total knee arthroplasty with an anticipated tourniquet time of 100 minutes. Which of the following is the STRONGEST contraindication to a sciatic nerve blockade?

A) Anticipated tourniquet time of 100 minutes
B) Obesity (BMI = 39)
C) Total knee arthroplasty
D) Valgus knee deformity of 15 degrees