It is very important to assess a patient’s knee range of motion to determine if there is any mechanical block, lack of motion due to arthritis or previous surgery, or increased motion due to a ligament injury. While doing this, it is ideal to compare it to a patient’s normal contralateral knee. Limitation of knee motion can be due to an acute injury, mechanical block, residual stiffness from a previous injury or surgery, arthritis and other pathologies. Increases in motion are almost always due to injuries.