The popliteal angle is the angle between the thigh and calf, when the thigh is drawn up close to the body and the calf is pulled upward as far as is comfortable to the patient. The popliteal angle is one way that doctors, physical therapists and other medical professionals measure how tight a patient's hamstring is. If a patient's hamstring is abnormally tight or the patient is able to extend his leg further than normal, it could be a sign of an injury, or a condition such as cerebral palsy. The degree measurement of a popliteal angle that is considered "normal" differs greatly depending on the age of the patient.
Lay the patient flat on his back.
Draw one of the patient's thighs up to his stomach. His knee should be bent, so his knee is near his face and his foot is by his rear. Keep your hand pressing down gently on the patient's knee, to keep the knee drawn up near his face.
Pull the patient's ankle -- the one on his bent leg-- up toward the sky, using your free hand. Maintain your pressure on the patient's bent knee simultaneously.
Pull the patient's ankle up toward the sky until you feel resistance to the movement upward from the patient's leg. Don't force the patient's leg to extend further. Keep the patient's leg bent at the same angle throughout the measuring process.
Place the fulcrum of the goniometer at the patient's knee joint. Extend one of the arms of the goniometer so it is parallel with the patient's thigh, and extend the other arm of the goniometer so it is parallel to the patient's calf.
Read the dial of the goniometer -- the measurement of the patient's popliteal angle will be given in degrees on the face of the goniometer's dial.