Knee Pain

Information About Knee Pain Causes for Patients in OR, WA, and AZ

Why Do I Have Knee Pain?

The knee is the body’s largest joint and enables people to perform virtually all movements, from walking and running to dancing and cycling. Since the knee plays such a vital role in everyday activity, it can be devastating when it becomes painful or is no longer functioning well.   

Knee pain occurs both in aging adults, as well as in younger people who have played sports or sustained a prior knee injury such as an ACL or meniscus tear. Certain activities can accelerate the deterioration of knee function and degradation of tissues inside the joint. At Reflex Knee Specialists, our team of providers utilizes ultrasound to identify the specific cause of knee pain and customize a non-surgical treatment plan to address each patient’s specific condition.  Our providers recommend solutions for many conditions affecting knee joints to patients in Portland, Oregon; Bellevue, Washington; and Tempe, Arizona. Learn more about knee pain causes and available treatment options.

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How the Knee Functions

The knee is comprised of three bones plus supporting ligaments and tendons. The portion of the bones that move across each other are covered by a specialized cushioning tissue called cartilage. In addition to the femur and tibia, the knee contains the patella (kneecap).

The surface of the tibia also features two menisci, which function as shock absorbers in the joint. The inner meniscus is called the medial meniscus, and the outer one is called the lateral meniscus. The menisci are made of fibrocartilage and help shift weight between bones; they are also integral to stabilizing the knee.

The knee also has ligaments, which support the knee joint by providing stability and protecting it from twisting. Muscles in the knee allow for bending, stretching, and turning, and tendons connect these muscles to the bones.

Common Causes of Knee Pain

Various components work together to provide mobility and stability to the complex structure of the knee. Even if just one element within the knee sustains damage, a person may develop pain. In other cases, multiple parts of the knee can be affected. The following are conditions or injuries that often cause knee pain:


Osteoarthritis (OA) is the most common cause of knee pain in the world.  It is a chronic and progressive degenerative joint disease characterized by chronic inflammation. Cartilage is the specialized tissue that covers the joint surfaces to provide a smooth movement and to minimize friction between the bones. In the presence of chronic inflammation, the cartilage destabilizes and begins to break down.  Any damage to or loss of cartilage is irreversible, so it is important to stop progression of disease in the early stages of OA. When cartilage begins to break down, joint mechanics are impaired which causes issues with the bones, ligaments, and muscles. OA can progress to a point where cartilage is completely lost and the bones rub against each other.  This is often referred to as “bone-on-bone arthritis”.

Symptoms of OA include joint pain, swelling, stiffness, and limited flexibility. Some people are more at risk of developing OA than others, including those who have had a prior knee injury or have played sports; other risk factors include poor alignment, obesity, advanced age, and genetic predisposition. People who have jobs that involve repetitive motion or a lot of squatting or heavy lifting may also be more susceptible to OA. For these reasons, even people in their 20s or 30s can be diagnosed with osteoarthritis (OA). 

Signs a person might be developing OA include:

  • Joint stiffness, particularly in the morning and when standing up
  • Cracking, grinding, or popping when walking, squatting, or similar movements
  • Discomfort whenever walking up or down stairs
  • Sharp knee pain while playing sports or pain or swelling after playing
  • Needing to take painkillers to play sports or taking them right after athletic activity
  • Soreness or aching in the knee, especially during movement
  • Knee pain or swelling with overuse or extensive inactivity

Unfortunately, there is no current cure for OA.  However, there are numerous treatments and lifestyle changes that can help manage the pain and slow the progression of tissue damage and joint dysfunction. Learning about osteoarthritis can also help individuals better understand the disease and take steps to minimize their risk of further joint damage.

Knee Injury

Knee injuries may develop from sports or work-related incidents such as falls, car accidents, or similar occurrences. The following are some examples of knee injuries:

  • ACL Tear or Rupture
  • Torn Meniscus
  • Ligament Strains
  • Tendon Injuries
  • Cartilage injuries and disorders

Knee injuries compound a person’s risk of developing OA. Research has found that individuals who experience a significant knee injury are much more likely to develop OA than others. For example, 50% of people who have a torn ACL will develop OA and structural damage to the knee within 10 years; within 15 years, this jumps to 75%.  This is highly concerning since the most common age of ACL injury is during the teenage years.  When the primary cause of OA is a knee injury, it is called post-traumatic osteoarthritis.

Torn Meniscus

A torn meniscus is one of the most common knee injuries. People who play contact sports are particularly at risk for this injury. Athletes who perform twisting or pivoting motions repeatedly, like soccer and basketball players, are also at risk. However, a torn meniscus can happen at any point and in any person, regardless of age.

A torn meniscus may derive from acute trauma or gradual degenerative changes. The latter is more likely to occur in older adults. These tears are classified by where they occur and their appearance. Bucket-handle, flap, and radial meniscus tears are some of the most prevailing types. Symptoms of a torn meniscus may include:

  • Swelling or stiffness in the knee
  • Knee weakness (feeling that the joint might give way)
  • Discomfort when bending or rotating the knee
  • Feeling that the knee is catching or locking
  • Inability to straighten the knee or maintain a full range of motion

People can often still walk with a torn meniscus without difficulty, and athletes may be able to play with the tear for a short time. Within a few days, though, symptoms will typically worsen.

The good news is that most meniscal tears do not require surgery. Research has shown similar outcomes following physical therapy and surgery. Most meniscal surgeries do not involve repair of the tear; instead, the procedure is only removing the damaged tissue. Removing meniscal tissue accelerates damage to the underlying cartilage and increases the risk of needing a total knee replacement. For these reasons, it is important to be evaluated by a knee specialist to explore non-surgical treatments before resorting to surgery.


Tendinitis occurs when tendons become inflamed and cause pain. It usually is caused by overuse and repetitive motions, but it can also happen following a sudden twisting motion or when the involved muscle is strained.

The following are key symptoms of tendinitis:

  • Pain felt during or after activity
  • Pain over the front of the knee between the patella (kneecap) and tibia (shinbone) may be due to patellar tendinitis
  • Pain over the front of the knee above the patella (kneecap) may be due to quadriceps tendinitis
  • Tenderness over the tendon

High-Impact Sports and Knee Pain

Athletes tend to put their bodies through more exertion than others and may wonder how this can affect their knees. Studies have shown that individuals who train, practice, and play high-impact sports are more at risk of developing osteoarthritis (OA). These sports include:

  • Basketball
  • Football
  • Skiing
  • Soccer
  • Tennis
  • Track and field
  • Ballet
  • Ice skating

Since they are at higher risk of developing knee OA, athletes and other active people should schedule an evaluation with a knee specialist.  About 40% of individuals who have irreversible structural knee damage have no symptoms. Incredible as it may seem, people can have damage to the cartilage and underlying bone without experiencing any pain.  This is why it is so important for active individuals to be evaluated and find out if they have any cartilage damage or other knee dysfunction before it worsens.

Treatments for Various Causes of Knee Pain

Although the causes of knee pain are wide-ranging, many treatments are available to help patients manage or overcome their symptoms. At Reflex Knee Specialists, our providers perform a comprehensive knee evaluation to determine the source of knee pain along with the best treatment path to help our patients achieve their goals.  Our team delivers a host of non-surgical solutions to knee pain, including:

  • Joint fluid therapy: This non-invasive treatment relieves pain and reduces inflammation inside the joint. This procedure is also called viscosupplementation, and is covered by most insurance companies.
  • PRP therapy: Platelet-rich plasma therapy involves extracting platelets from a sample of blood and injecting them into the knee joint.  Platelets contain numerous growth factors that reduce inflammation and pain.  Treatment with PRP also improves the quality of the joint fluid which provides additional cushioning protection for the cartilage inside the joint. This treatment is not yet covered by insurance companies.   
  • Physical therapy: When a person is experiencing pain with certain activities, changes are made in the way that person will stand, walk, and move. These changes are known as compensatory patterns, which can cause problems in other areas of the body. A skilled physical therapist is able to identify these subtle changes in movement and recommend stretches and exercises to help correct them. Proper movement of the knees (and other parts of the body) is essential for overall joint health. Our Physical Therapists help optimize biomechanics so our patients can achieve pain relief and lasting knee health for the long term.
  • Knee bracing: Off-loading knee braces safeguard the most damaged areas inside the joint and correct knee alignment. They can also facilitate better mobility and decrease fall risk.

Schedule an Appointment Today with Reflex Knee Specialists

No matter what is causing your knee pain, the experts at Reflex Knee Specialists have the training and expertise necessary to identify the source of pain and to provide effective, non-surgical treatments. Our skilled specialists take an integrative approach to care at our offices in Portland, Oregon, Bellevue, Washington, and Tempe, Arizona. They use innovative methods to alleviate pain and rely on diagnostic knee ultrasound to confirm the accuracy of each treatment. To schedule an appointment and learn more about the benefits of an individualized and comprehensive treatment plan for knee pain, call or contact us today.