What Causes Sharp, Stabbing Pain at the Back of the Leg, Behind the Knee?

Acute stabbing pain at the back of the leg or behind the knee may appear suddenly. This type of knee pain is particularly intense and may significantly impact an individual’s quality of life. 

Stabbing pain behind the knee may be caused by different issues, from overuse of the joint to medical conditions like osteoarthritis or blood clots(1-2).

Knee pain may impact an estimated 25% of American adults⁽¹³⁾. Istabbingndividuals may overcome this type of leg pain with the right medical advice and physical therapy. 

Health Report Live is the primary source of healthcare information for seniors. This article will cover the anatomy of the back of the knee, the common causes of knee pain, and what individuals can do about the shooting pain at the back of the knee.

Back of Knee Anatomy

Understanding what is causing the sharp stabbing pain in the back of the leg behind the knee starts with looking at the different parts of the knee’s anatomy. 

The knee is a complex mechanical joint, and everything from back pain to an individual’s overall healthcare may affect the knee joint.

The knee is the immense joint in the human body⁽⁴⁾. This body part is a significant intersection of muscle, bone, and supporting tissues. The knees also have a significant role in supporting the body while walking and even doing work while at rest.

Meanwhile, there are a few terms for the back of the knee. This body part is technically called the popliteal fossa, commonly called the hough or the “kneepit.”

An injury to the hamstrings, ligaments, or even lower back injuries can cause sharp pain in the back of the knee⁽⁵⁾. Below is a quick overview of the back of the knee anatomy.

There Are Four Major Ligaments in the Knee

Four major ligaments support the knee. These tissues deliver stability to the knee and are vital for helping humans stand and move without falling.

There are two ligaments inside the knee itself. The anterior cruciate ligament, or the ACL, is in the center of the knee and controls forward motion while giving the shin stability. Meanwhile, the posterior cruciate ligament, or PCL, controls the backward movement of the shin.

Furthermore, two other sets of ligaments support the knee. The medial collateral ligament (MCL) supports the inner knee, while the lateral collateral ligament (LCL) supports the outer knee.

These ligaments may be damaged or torn, leading to sharp pain in the knee, especially while under stress⁽⁶⁾.

There Are Two Major Tendons in the Knee

The knee is characterized as a complicated network of tendons that attach muscles to bone. 

The knee consists of two major tendons: the quadriceps tendon and the patella tendon. The knee also has the hamstrings tendon and the iliotibial band.

Damage to the hamstrings tendon may cause both leg and knee pain. 

A condition known as Jumper’s Knee may cause stabbing knee pain. Another term for this condition is patellar tendinopathy⁽⁷⁾.

While they are not tendons, two pieces of cartilage inside the knee are vital. The knee’s lateral and medial menisci may act as “shock absorbers.” They may wear down over time or due to medical conditions, leading to stabbing pain sensations while the knee moves or under stress.

Bones in the Back of the Knee

The knee consists of four major bones. The three bones of the leg are the femur, tibia, and fibula. 

Moreover, there is also the kneecap, also known as the patella. Damage to these bones may often cause pain or may feel like pain coming from the back of the knee⁽⁸⁾.

Nerves in the Back of the Knee

Nerve damage, and a pinched nerve, are common causes of stabbing knee pain in the back of the knee⁽⁹⁾. The knee is a complex moving joint, and pinching a nerve is a reasonably common problem in this body area.

The knee has several nerves that run through the length of the leg. These include the tibial nerve, common fibular nerve, and several smaller nerve branches.

Individuals may ask, “How do you get rid of nerve pain behind the knee?” Nerve damage is an often overlooked cause of knee pain(10). 

Treatment options for this type of knee pain include over-the-counter medications, surgery, and physical therapy⁽¹¹⁾.

Muscles in the Back of the Knee

The knee has two significant groups of leg muscles. The quadriceps are located on the anterior side of the knee and the femur, while the hamstrings connect on the posterior side and cover the lower leg.

Stabbing pain in the back of the knee may be a sign of problems with the hamstrings⁽¹²⁾. 

It is more likely that the hamstrings are the culprit here as this is the muscle group that connects on the back side of the knee.

Furthermore, individuals may think that the cause of the pain behind their legs or their knees and calves may be related to their hamstrings. However, this pain may also be caused by muscle spasms⁽¹³⁾. 

Chronic knee pain may even lead to a slight reduction in physical strength in the leg muscles⁽¹⁴⁾.

Arteries in the Back of the Knee

One of the most vital things individuals should keep in mind is that the knee is one of the body’s major intersections. This intersection is one of those locations wherein systems in the body branch out into new systems. The femoral artery extends to the back of the knee and becomes the popliteal as it passes through the knee.

The knee is the intersection of five other constant arteries. Thus, the knee is a complicated network of blood vessels, veins, and arteries. Blood clots and other problems with the arteries may be felt as a stabbing pain in the back of the knee⁽¹⁵⁾.

Severe medical conditions like peripheral arterial disease often feature joint pain, including the knee, as a common symptom⁽¹⁶⁾.

Pain at the Back of the Knee

Sharp stabbing pain behind the leg or the knee might feel clear as day, but informing a doctor what the pain is like could still be a challenge. 

Pain is a normal response to injury. It is caused by particular types of nerves, called nociceptors, which use the feeling of pain to limit mobility, reduce the risk of further damage, and alert individuals to injuries.

Pain is a personal experience. People experience pain differently and use different phrases to describe how they are experiencing pain. Factors like pain tolerance, acceptance, and pain-related anxiety may change how our knee pain rates on a pain measurement scale⁽¹⁷⁾.

In order to get help for stabbing knee pain, individuals need to be able to describe this pain to their doctor. Here are a few quick things individuals can do to better express their knee pain to a doctor.

It would be best if individuals wrote down the specifics of their knee pain. Is the pain in a specific spot, or does it feel like it is coming from the general area of the knee? Does the pain flare up during physical activity or during long periods of rest?

Identifying the specific nature of the pain will help doctors locate the cause of the knee pain.

One common cause of stabbing pain in the back of the knee is a problem with the hamstrings or the three muscles around the back of the thighs to the knees. The tendons that connect the hamstring muscle to the back of the knee can become inflamed when it is overused or due to arthritis⁽¹⁸⁾. This overuse often happens when individuals exercise too much or stretch beyond their limits.

If the stabbing knee pain comes with swelling and a general feeling of tightness, it could be caused by a popliteal bursa, also known as Baker’s Cyst⁽¹⁹⁾. 

This medical issue is due to a buildup of fluid usually caused by a physical problem in the knee.

The meniscus, the knee’s shock absorber, is also a common cause of shooting pain in the knee⁽²⁰⁾. As this pad wears down, the knees become more prone to damage and pain.

Meanwhile, patellar tendonitis, which is also called jumper’s knee, may cause pain and inflammation around the patellar tendon located near the kneecaps (patella) to the skin bone (tibia)⁽²¹⁾. 

This condition usually occurs due to overusing the knee joint and activities involving frequent jumping on solid or hard surfaces. Moreover, repeated force and stress on the tendons may lead to inflammation⁽²²⁾. 

Another condition that causes pain on the knee, specifically the patella, is patellofemoral pain syndrome or runner’s knee. TThis condition causes weak muscles due to wearing shoes with poor foot support or running with the feet pulling the kneecap forwards⁽²³⁾. 

There are also medical illnesses that could cause stabbing pain in the back of the knee. These medical issues include osteoarthritis, gout, and even circulatory problems, leading to blood clots. 

Injuries to the joints caused by sports or accidents may also cause osteoarthritis. Some injuries that occurred years ago may still increase an individual’s risk of developing this medical condition⁽²⁴⁾.

This medical condition may develop gradually and may worsen over time. Symptoms of osteoarthritis include pain and stiffness around the knees, spine, and hips, joint tenderness, particularly when applied pressure, loss of range of motion, and inflammation around the soft tissue joints⁽²⁵⁾. 

Due to so many potential causes of pain in the back of the knee, it is essential to know how doctors diagnose knee pain.

The physician might also do a blood or urine test to check for conditions like infections or rheumatoid arthritis. 

Moreover, the medical expert may also perform a procedure called arthrocentesis, wherein a small amount of liquid is removed from the inside of the knee joint using a needle and sent to the laboratory to analyze⁽²⁷⁾. 

Other Pain in the Knee

One of the biggest challenges in diagnosing knee pain has to do with the fact that pain in the knee is often generalized. 

Individuals could be experiencing pain coming from the back of the knee but may actually be caused by damage inside the knee, on the side, or even on the front of the knee.

Doctors may want to check an individual for common types of pain in another knee, leg, and lower back areas. This examination includes checking for sacs, bursts, and cysts. The medical practitioner is likely to focus on problems that may arise on the outside and inside of the knee.

The knee is a sensitive part of the body, and too much and too little exercise may cause problems like sprains, sports injuries, and cramping. 

Let us look at other types of pain that may be confused with pain in the back of the knee.

Pain on the Outside of the Knee

It is prevalent for individuals to describe pain on the back of the knee when it is actually caused by a problem on the outside of the knee. 

While there are specific medical definitions for areas in the knee, in day-to-day practice, there is much overlap between what counts as the outside of the knee and what counts as the back of the knee.

If individuals have been experiencing a burning sensation that comes with their knee pain, they could be experiencing problems with their iliotibial band⁽²⁸⁾. 

The iliotibial band is a tendon that runs from the outer thigh to the knee. It may become inflamed, damaged, or infected, which may cause stabbing knee pain.

Pain on the Inside of the Knee

The inside of the knee is often a common location for injuries and dysfunctions that may cause stabbing pain in the back of the knee. There are two primary causes of this pain.

The menisci provide a cushion between the bones of the knee. This cushion absorbs the shock of walking, standing, and moving the leg. These cushions can tear, wear down, and develop cysts, leading to shooting pain in the knee⁽²⁹⁾.

There is also a fold of tissue called the medial plica, which can be the source of pain inside the knee⁽³⁰⁾. This fold may wear down through overuse and is a common condition in athletes and fitness buffs. 

Damage to the medial plica is likely underdiagnosed but may be detected with an MRI.

Swelling of the Knee

Swelling is commonly one of the first symptoms of knee and leg pain⁽³¹⁾. Swelling is part of the body’s response to infection and injury, but it may also be a cause of pain and discomfort.

One of the most frequent causes of swelling of the knee is injury⁽³²⁾.

These injuries could be as extreme as a sporting injury or mild as bumping the knee against a hard surface. 

When tissues swell, they press down on nerves, which causes pain that can often feel throbbing as blood flow is also obstructed.

Individuals may have heard the phrase “water on the knee” before. The medical term is knee effusion, which is caused when fluids build up inside the tissues in the knee⁽³³⁾.  

A doctor will likely have to do a test to diagnose the cause of the individual’s knee effusion, but effective treatment may reduce this fluid buildup and remove the cause of the pain.

Gout and pseudogout are common causes of stabbing knee pain. This medical illness is a type of arthritis that can affect anyone⁽³⁴⁾. Gout often appears as bright red swelling around the knee that comes with shooting pain.

Gout may be caused by a buildup of uric acid in the tissues. Gout usually does not cause any permanent damage to the knee, but individuals should get to a doctor quickly in order to reduce the likelihood of long-term problems.

A medical expert will help individuals find a treatment that may range from surgery to over-the-counter medications. Anti-inflammatory medication is a common choice for relieving knee pain⁽³⁵⁾.

Health Report Live has the best information for seniors looking to stay on top of their health. Whether individuals are concerned about knee pain or other healthcare issues, our articles are the best place to start for their healthcare.