Which of the following describes the effect on the lumbar spine of a subject standing in excessive bilateral genu recurvatum?

a. Compensatory increase in lumbar lordosis
b. Compensatory increase in lumbar kyphosis
c. Compensatory increase in thoracic lordosis
d. Compensatory increase in thoracic kyphosis

ANS: A
Because many of the muscles associated with the knee are two-joint muscles that cross both the hip and the knee, hip joint position can influence the range of motion (ROM). Increased lumbar lordosis leads to an anterior pelvic tilt pulling the relative line of gravity (LoG) anteriorly. As the LoG passes anteriorly to the knee joint, it pulls the femur anterior on the tibia. Normally the force of the posterior joint capsule of the knee is effective in resisting this gravitational torque. However, over time, the capsule may lengthen and allow hyperextension of the knee, known as genu recurvatum.