Pain When Flexing the Knee and How to Treat It

man holding knee from pain

Understanding Knee Pain

Pain when flexing the knee is a common complaint among people of all ages. Knee pain can range from a minor nuisance to a debilitating condition, making it difficult to walk, climb stairs, or perform other daily activities. The knee joint is a complex structure, and there are several potential causes of pain when flexing the knee. In this article, I’ll explore the causes of this pain, how it can be treated, and ways to prevent it.

The knee

The knee is made of two joints: the tibiofemoral joint, between the femur (thigh bone) and tibia (shin bone), and the patellofemoral joint, between the femur and patella (knee cap). Each is an anchor point for multiple tendons and muscles.

More severe pain when flexing the knee can be the result of injury to the knee. In some cases, the cause of the pain may be difficult to diagnose because some injuries or strains have symptoms similar to other conditions.

Causes of Pain When Flexing the Knee

The most common causes of knee pain are related to aging, injury, overuse or repeated stress on the knee. Common knee problems include sprained or torn ligaments, cartilage tears, tendonitis and medical conditions such as arthritis. Additionally, a muscle imbalance combined with repetitive movement can irritate structures of the knee and lead to anterior knee pain, or general pain in the front of the knee. These injuries are often a result of repeated strenuous activity over time, not allowing the soft tissues sufficient time to heal properly.


knee x-ray
An x-ray of the knee

Arthritis is a common cause of pain when flexing the knee. There are several different types of arthritis that can affect the knee, including osteoarthritis, rheumatoid arthritis, and post-traumatic arthritis. Osteoarthritis is the most common form of arthritis and is caused by wear and tear on the joint. It typically occurs in older adults and is characterized by a gradual loss of cartilage, the protective tissue that cushions the bones in the knee. Rheumatoid arthritis, on the other hand, is an autoimmune disorder that causes inflammation in the joint. It can occur at any age and affects the lining of the knee joint. Post-traumatic arthritis is a form of arthritis that develops after a knee injury.

Pain and swelling are the most common symptoms of knee arthritis. Other symptoms include:

  • Creaking, clicking or snapping noises
  • Joint pain that gets worse or better depending on the weather
  • Stiffness in the knee
  • Knee buckling or a feeling of not being able to hold body weight
  • Red and/or warm skin
  • Pain when walking

Meniscus Tears

A meniscus tear is a common knee injury that occurs when the cartilage in the knee joint is damaged. The meniscus is a C-shaped piece of cartilage in the knee joint that acts as a cushion between the thighbone and the shinbone. The meniscus helps to stabilize and absorb shock in the knee joint. When the meniscus is torn, it can cause pain, swelling, and difficulty moving the knee.

A meniscus tear can be caused by a variety of factors, including overuse, sudden twisting or bending of the knee, and trauma to the knee. Athletes, especially those who participate in sports that involve a lot of cutting and pivoting motions, such as soccer, football, and basketball, are at a higher risk of suffering a meniscal tear. Age also plays a role, as the meniscus tends to weaken with age, making it more prone to tearing.

Symptoms of a meniscus tear include pain, swelling, and stiffness in the knee. The knee may also feel unstable or “give out” when bearing weight. In some cases, there may be a popping or snapping sound when the tear occurs. The knee may also be swollen and warm to the touch, and there may be a limited range of motion in the joint.

Quadriceps Muscles

The quadriceps are a group of four muscles located on the front of the thigh. The quadriceps are responsible for extending or straightening the knee joint and for stabilizing the kneecap (patella) and keeping it in a straight line.

Overworking the muscles and joints during exercise like running or weight training can cause the quads to tighten. Standing and sitting with the knees hyperextended can also cause tightness in the quads. This muscle tightness can lead to misalignment of the kneecap. The misalignment causes strain on the knee joint and that unstable feeling that the knee may “give out.” Pain in the kneecap is also known as patellofemoral pain syndrome and most commonly affects teenagers, athletes (runner’s knee) and manual laborers.

It can be hard to tell if your quads are tight, but there’s an easy way to find out. Lie face down on the floor or in bed, bend a leg and reach around with your hand to grab your ankle. Pull your foot towards yourself, trying to get the heal of your foot to your butt. If you can’t touch your butt with your foot or if you feel knee pain as you try to do that, you probably have tight quadriceps.

Baker’s Cyst

A Baker’s cyst is a fluid-filled growth on the back of the knee, usually caused by knee-joint conditions such as arthritis or a cartilage tear. These conditions cause the knee to produce too much lubricating fluid. A Baker’s cyst usually causes a bulge and tight feeling behind the knee.

Patellar Tendinitis

Patellar tendinitis, also known as jumper’s knee, is an injury to the tendon connecting the kneecap to the shin bone. The patellar tendon helps the muscles at the front of the thigh that extend the knee when kicking, running and jumping.

Like many of the other conditions listed here, knee pain, swelling, and stiffness are common symptoms.

ACL Tears

runner with knee pain

One of the most painful and devastating knee injuries is a tear of the anterior cruciate ligament, more commonly referred to as the ACL. The careers of many professional and college athletes have been ended by an ACL tear. A torn ACL is a very painful injury and can debilitate a person for several months and for life in some cases.

The ACL is one of the key ligaments that helps stabilize the knee joint. The ACL connects the thighbone to the shinbone. ACL injuries generally cause swelling, stiffness, and severe pain. Many times, a “popping” noise can be heard when an ACL is torn. This injury can occur from changing direction rapidly, slowing down abruptly when running, and landing forcefully from a jump.

Femoral Condyle Chondromalacia

The femoral condyles are located on the end of the thigh bone. They are covered in cartilage and function as a shock absorber for the knee. When the knee is flexed, the thigh bone and shin bone rub together, causing friction. This friction can result in pain, grinding, and limited function.

Femoral condyle chondromalacia is caused by an irritation of the end of the femur. It can be the result of normal wear-and-tear as we age, or it can be due to an injury or long term overuse from sports.

Treatment for Pain When Flexing the Knee

The treatment for knee pain depends on the underlying cause, therefore it’s imperative to understand what is causing the symptoms and the severity of your condition before starting a treatment plan. The only way to diagnose the condition with certainty is to consult with your health care provider. Your doctor will then recommend the appropriate course of treatment which may include physical therapy, medications, or surgery.


This is obvious, but for most common conditions, resting the knee and avoiding activities that may have caused the condition will help the knee start to feel better.

Ice and Heat

Ice packs and heating pads can help a knee start to feel better.

Stretching and Low Impact Exercises

woman stretching her left leg

Stretching the muscles and tendons around the knee helps flexibility and can often help with some causes of knee pain. Low-impact exercises like swimming or using an exercise bike or elliptical machine can help relieve knee pain. Therapeutic exercises like leg lifts and step-ups are effective and can be done at home without special equipment.

Physical Therapy

Physical therapy can be an effective treatment for pain when flexing the knee. Physical therapists use different methods to increase strength, improve mobility, and help return patients to their pre-injury level of comfort and activity. Your physical therapist may also provide exercises and stretches like the ones previously mentioned to help reduce pain and improve range of motion.


Medications can be used to reduce inflammation and relieve pain when flexing the knee. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen are commonly used to reduce inflammation and pain. Your doctor may also prescribe stronger medications such as corticosteroids or opioids if needed.

Cortisone injections

Cortisone is a type of steroid medication that can be used to reduce inflammation and pain in the knee. When injected directly into the knee joint, it can provide relief for conditions such as osteoarthritis, rheumatoid arthritis, and bursitis. The medication works by reducing inflammation and swelling, which in turn can help to alleviate pain. It can also help to improve mobility and function in the knee. However, it’s important to note that cortisone injections are not a long-term solution and should be used in conjunction with other forms of treatment, such as physical therapy and exercise.


In some cases, surgery may be necessary to treat pain when flexing the knee. For example, if the pain is caused by a meniscus tear, a minimally invasive arthroscopic procedure may be used to repair the tear. For people of about 50 years of age or older who suffer from osteoarthritis, a consultation with an orthopedic surgeon to see if they are a candidate for knee replacement may be necessary.

Prevention of Pain When Flexing the Knee

The best way to prevent pain when flexing the knee is to take steps to protect the joint. There are several things you can do to reduce your risk of pain when flexing the knee.


Exercising regularly can help to strengthen the muscles and ligaments around the knee joint, which can help to reduce pain and improve mobility. Low-impact exercises such as swimming and biking are particularly beneficial for the knee.

man exercising

Weight Management

Maintaining a healthy weight is important for the health of the knee joint. Being overweight or obese can put extra stress on the knee, which can lead to pain when flexing the knee. Your healthcare provider can help design a weight management program including diet and exercise for you if needed. Keeping your weight under control can also help should you need knee replacement surgery as being overweight can make recovery more difficult.

Proper Footwear

When I was in my 30’s, I went to the doctor because I was experiencing terrible knee pain.  My doctor helped me realize that a new pair of leather-soled dress shoes were the cause of the knee pain. It was then that I learned firsthand that wearing proper footwear is important for the health of the knee joint. Shoes should provide adequate cushioning and support for the feet and provide a stable base for the knee joint. Improper footwear can also exacerbate muscular imbalances. In my case, the leather soles of my shoes did not provide adequate traction on the marble floor in my office.

A Common Problem But Treatable

Pain when flexing the knee is common among people of all ages. It can be caused by a variety of conditions, including arthritis, meniscus tears, and quadriceps muscle strains. Treatment for knee pain depends on the underlying cause and may include physical therapy, medications, or surgery. To reduce the risk of pain when flexing the knee, it is important to take steps to protect the joint, such as exercising regularly, maintaining a healthy weight, and wearing proper footwear. If you are experiencing pain when flexing the knee, it is important to speak to your doctor so that the cause can be identified and the most appropriate treatment can be provided.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *