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1/18/2019 2:05:36 PM

Identifying the underlying cause of knee pain

Next to back pain, knee pain is one of the most common complaints among both older adults and younger athletes. Knee injuries are one common cause of knee pain, but you don’t have to fall, trip or get into some type of accident to hurt your knees. How do you relieve knee pain? Identifying the underlying cause of your pain is the first step.

Common Causes of Knee Pain

Knee pain describes any type of discomfort that affects the knees, such as sensitivity and throbbing. It’s common for knee pain to also be accompanied by other symptoms affecting the legs, which can include:

Swelling around the knee

Discomfort that gets worse when walking, squatting or doing other exercises

Inability to bear weight on the knee

Stiffness and reduced ability to move the knee, such as having a hard time straightening and bending the knee

Weakness in the affected leg

Redness and warmth around the kneecap


General reduced range of motion of the legs

Feeling like your knee “gives out” when you try to move

Unusual sounds when moving the knee, such as a popping or crunching sound

The knee joint, a complex part of the body that is formed by interconnecting bones, cartilage and ligaments, is where the major bones of the upper leg and lower leg meet. The knee is actually the largest joint in the human body and functions as a “hinge joint”, formed by the femur (thigh bone), the tibia (shin bone) and the patella (the knee cap) that are held in place by several joints/tendons. The knees must withstand pressure, weight and shock, and rely on the muscles in the legs to keep them stable and strong.

Knee pain is sometimes referred to as patellofemoral pain syndrome or runner’s knee, which describes pain and other symptoms affecting the area between your patella (kneecap) and femur (thighbone). It’s possible for knee pain to be either chronic or acute. Chronic pain is the kind that does not come on suddenly and continues to get worse. It usually lasts 4–6 weeks or longer.

Acute pain happens “spur of the moment”; you feel the effects right away. You might develop acute pain following a sudden injury and hear a “popping noise” or feel sharp pains immediately. Acute knee pain can cause you to fall down in agony and keep you from being able to move much afterwards.

Most Common Knee Pain Causes:

Injuries to the legs, including any injury that affects the cartilage, ligaments, tendons or fluid-filled sacs (bursae) near the knees

Arthritis, which can include rheumatoid arthritis (an autoimmune condition that affects joints) or osteoarthritis (degenerative arthritis which usually affects older adults); more than 20 million people in the U.S. alone suffer from knee osteoarthritis (OA), which is “one of the top five most disabling conditions that affects more than one-third of persons 65 years of age or older”.

Biomechanical problems, such as poor form, deformities or muscular compensations that cause the kneecap to fall out of its optimal position

Gout, characterized by uric acid or calcium-containing crystals forming on the joints

Joint mice: a more rare disorder in which one or more small fragments of bone or cartilage break off and remain floating in the knee joint space

Infections that can cause fluid retention and swelling, such as septic arthritis

Knee Injuries that Cause Knee Pain:

Knee injuries can slowly develop or over time, or happen suddenly due to impact. Injury to the knee can be due to ruptured ligaments, torn cartilage or irritation/inflammation of the knee joint caused by overuse. Examples of specific injuries and conditions that can lead to knee pain are:

Iliotibial band syndrome, or irritation and inflammation of the IT band, the thick fascia/tissue that extends from the pelvis/hip to the knee

Torn meniscus, or damage to the meniscus which is a tough, rubbery cartilage that helps absorb shock in the legs

Patellar tendonitis, caused by inflammation of the patellar tendon, which connects the kneecap to the shinbone

Knee bursitis, or inflammation in the bursae (small sacs of fluid) that cushion the outside of the knees

Chondromalacia patella, which refers to damaged cartilage under the kneecap

Tearing of the ACL (the anterior cruciate ligament which connects the shinbone to the thigh bone); both traumatic and non-traumatic injuries commonly affect the ACL

Fractures of the patella (kneecap), which can be caused by impact or degenerative diseases

Dislocated kneecap, when the patella slips out of its normal position

Risk Factors for Developing Knee Pain

What types of health conditions, exercises and lifestyle habits put you at risk for knee pain? These can include:

Engaging in contact or risky sports like skiing, football, basketball, soccer, lacrosse or rugby which can result in collision, impact or falling.

Being a distance/endurance runner or cyclist, which can cause overuse of the knees. Doing lots of jumping or walking uphill and downhill can also put added strain on the knees. Sometimes even recreational running or normal exercise can be enough to trigger knee pain.

Being a female athlete. Female athletes are more prone to suffering from traumatic knee injuries and experiencing recurring knee pain. It’s believed this is due to the anatomy of the female pelvic region and the way that females activate the muscles in their legs.

Twisting motions at the knee while bearing weight, such as when exercising or if you have an active job that involves lifting.

Poor training technique and posture, including sudden changes in the amount, frequency or intensity of workouts, as well as inadequate rest between workouts.

Being in an accident, such as a vehicle collision.

Falling or tripping, such as due to loss of balance in older age.

Osteoporosis, which can make you more prone to knee fractures and weakened bones in the pelvis and legs.

Having an autoimmune disorder, especially rheumatoid arthritis.

Having hip or foot pain, which can cause compensations that put damaging forces on the knees.

Being overweight or obese, which adds extra pressure to the knees.

Being sedentary (not exercising, walking or stretching much), which can cause weakness in the legs and loss of flexibility.

Having a previous injury that affects the knees or legs.

Knee Pain Diagnosis

To diagnose you with a specific type of knee pain, your doctor (such as an orthopedist) will need to perform a physical exam and check to see how you respond to different movements using your legs. If your pain increases when the knee is moved in one specific direction, or when performing a movement like standing up, it can point to which exact part of the knee is damaged or inflamed. You might also need X-rays, a CT scan, or potentially an MRI or ultrasound to confirm a diagnosis.

You want to talk to your doctor about which specific symptoms you’re experiencing, when they started and what types of things make the pain better (taking rest days, stretching, etc.) Pay attention to whether your knee bothers you when you’re sitting down, exercising or just going about your day. Does your affected knee ache throughout the whole day? Does it bother you while you sleep? Is it only a problem when you’re bearing weight, running or walking uphill? All of these are useful things to discuss with your doctor.

Keep these in mind when discussing your symptoms and treatment options with your doctor:

If you feel pain in front of the knee (behind the kneecap), this is a sign of patellofemoral syndrome. The pain is due to abnormal tracking of the patella. You’re likely to feel pain when going from a standing to sitting position. You may notice that pain is worse when you first start moving, but the knee pain gets better when you’ve warmed up and started exercising.

How do you know if you have a torn meniscus in your knee? You’ll probably have difficulty walking, limited range of motion, swelling and stiffness. Twisting and rotating your knee will feel very painful. You probably won’t be able to bear weight or fully extend your knee.

The ACL is the first ligament that becomes tight when the knee is straightened, and it can become torn if the knee is hyperextended or from sudden stops, jumps or changes in direction during physical activity. Where does your knee hurt with a torn ACL? It can hurt all over, look very swollen and feel very weak. You might not be able to bend and straighten the knee, walk downhill or change directions easily, and may feel like your knee gives out easily. Some people also hear a “pop” when they tear their ACL and then have intense pain afterwards./.

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