Does knee position at the time of tourniquet inflation affect knee range of motion?

Pneumatic tourniquets about the thigh are commonly employed in lower extremity orthopaedic surgery to maintain a bloodless operative field. The purpose of this study was to determine whether the position of the knee at the time of tourniquet inflation has an impact on knee range of motion (ROM). Passive ROM of the knees of 30 patients was measured with the tourniquet deflated, with the tourniquet inflated while the knees were in extension, and with the tourniquet inflated while the knees were in flexion. The average knee ROM with a deflated tourniquet was 143.0 degrees with a standard deviation of 8.1 degrees (range, 125 degrees -160 degrees ). When the tourniquet was inflated with the knees in extension, the average knee ROM was 143.0 degrees with a standard deviation of 7.8 degrees (range, 125 degrees -159 degrees ). When the tourniquet was inflated with the knees in flexion, the average knee ROM was 143.7 degrees with a standard deviation of 7.8 degrees (range, 124 degrees -160 degrees ). There was a statistically significant difference between the ROM of knees with tourniquet inflation in flexion versus extension (p = .0011.) Although there was a statistical difference, it was concluded that a difference of approximately 1 degrees in knee ROM is not clinically relevant.