Feeling a pulse or a heartbeat in your knee can be an unexpected and concerning experience. This sensation often leads people to wonder about its cause and whether it signals a serious health issue. While it can be unsettling, the feeling is often related to normal body functions.
The Popliteal Artery and Normal Pulsations
Behind your knee is a space known as the popliteal fossa, which houses the popliteal artery. This major blood vessel is responsible for supplying blood to your lower leg. The sensation of a heartbeat in this area is the feeling of your pulse within this artery. Feeling this pulse is not inherently a sign of a problem and is more perceptible under certain conditions.
Increased blood flow following physical activity can make the pulsation more forceful. Certain body positions, such as crossing your legs or lying in a way that puts mild pressure on the artery, can also make the pulse more prominent. Individuals with a lower percentage of body fat may find the artery is closer to the skin’s surface, making it easier to detect.
Temporary increases in your overall heart rate can also amplify the sensation. Consuming stimulants like caffeine or experiencing heightened stress or anxiety can cause your heart to beat more forcefully, resulting in a more pronounced pulse throughout your body, including behind the knee.
Medical Conditions Causing a Knee Pulse
A persistent and strong pulse in the knee can be linked to an underlying medical condition affecting the popliteal artery. One such condition is a popliteal artery aneurysm, which is an irregular bulge or weakened area in the artery’s wall. This ballooning of the vessel can cause a noticeable pulsating feeling behind the knee.
Another condition that can lead to a more turbulent and perceptible blood flow is atherosclerosis. This involves the hardening and narrowing of arteries due to the buildup of plaque, which is composed of fats and cholesterol. The narrowed pathway can cause the blood to move with greater force, making the pulse easier to feel.
High blood pressure, or hypertension, is a systemic issue that increases the force of blood against the artery walls throughout the body. This elevated pressure can make every pulse feel stronger, including the one in the popliteal artery.
Associated Symptoms and When to Seek Medical Attention
While feeling a pulse behind your knee is often benign, certain accompanying symptoms should prompt a medical evaluation. A pulse that is persistent, very forceful, or feels like a throb warrants attention. If the sensation is combined with pain, tenderness, or cramping in the knee or calf, particularly during activities like walking, it may indicate a problem with blood flow.
The presence of a visible, pulsating lump or noticeable swelling behind the knee is another significant sign. You should also be aware of any changes in the lower leg or foot. Symptoms such as numbness, weakness, a persistent cold feeling, or changes in skin color, like paleness or a bluish tint, can signal insufficient blood supply.
The Diagnostic Process
If you seek medical attention for a pulsating sensation in your knee, a doctor will begin by performing a physical examination of the leg and knee. They will feel for a palpable mass in the area behind the knee and inquire about your medical history and any associated symptoms.
To get a clearer picture of the artery and blood flow, a physician may order diagnostic imaging. A common and non-invasive first step is a duplex ultrasound, which uses sound waves to visualize the popliteal artery and assess blood circulation. If more detail is required, a CT angiogram or an MRA may be used to create detailed images of the blood vessels and surrounding structures.