In steep Trendelenburg, why should the knees be placed over the distal break?

• A. To stabilize the pelvis
• B. To allow bending of the knees and protect from undue shear
• C. To improve venous return
• D. To maintain patient comfort

Answer: (B)

In steep Trendelenburg, gravity tends to make the patient slide toward the head end, creating shear forces at the back and buttocks if the body shifts on the table. Positioning the knees over the distal break allows the knees to bend, which serves as a natural shock absorber and weight distributor. This knee flexion dampens movement, reducing the longitudinal shear on soft tissues and helping keep the pelvis and spine more stable. The primary purpose of this placement is to protect the patient from undue shear by enabling knee bending, rather than merely improving comfort, venous return, or pelvic stabilization in isolation.