What does hyperextension of the knee mean: First of all, the knee, also known as the knee joint, is made up of the tibia, femur and patella together. Hyperextension of the knee is also called dorsiflexion or hyperextension. A normal knee is usually a straight line, or zero degrees. If the knee is hyperextended, or hyperextended, the distal end of the knee, the tibia, will overtake the femur forward, and this is called hyperextension of the knee. Hyperextension usually means that there may be ligament damage, but there are also conditions such as osteoporosis or laxity that can cause hyperextension.