Millions of Americans suffer from chronic pain due to arthritis every year. According to the Centers for Disease Control and Prevention (CDC), about one in four people with arthritis, or 15 million people, report experiencing severe joint pain.
Older adults, women, in particular, are most prone to having osteoporosis.
Children with arthritis can also experience pain. Unfortunately, information on pain in children with arthritis is not available.
Health Report Live reviewed the most up-to-date and authoritative sources to provide meaningful physical therapy and knee pain information.
Studies and research involving physical therapy and knee pain considered below include:
- Mayo Clinic
- Harvard Health Publishing – Harvard Medical School
- Journal of Orthopedic & Sports Physical Therapy (JOSPT)
- Annals of Internal Medicine
- Medicine Plus
- Nonsurgical Management of Knee Pain in Adults
- Clinical Journal of Sports Medicine
- Science Direct
What is Chronic Knee Pain?
Chronic knee pain is when an individual rates their pain at seven or more, on a scale of zero (no pain), to ten (as severe as it can be).
A report from the National Library of Medicine (NIH) reveals that severe arthritis-related joint pain affects all ages and races. The state-specific prevalence of severe joint pain in adults with arthritis varies depending on their age, from 20.8% in Colorado to 45.2% in Mississippi.
The prevalence of severe arthritis-related joint pain among adults in the United States was:
- Women are more likely to have severe arthritis-related joint pain (36.0%) than men (27.3%).
- The prevalence was highest among adults between 45 and 64 years old (35.6%). Next was among adults aged 18-44 years (33.0%), and the lowest was for those 65 years old or older (25.1%).
- The highest percentage of obese (37.2%) was higher than those who were overweight (28.6%) and underweight adults (29.1%).
Anatomy of the Knee
The knee is where the lower leg and the upper leg bones meet. The knee is the largest joint in your body and allows you to sit, squat, or walk.
Three bones make up the knee:
- Femur – the upper leg bone or the thigh bone.
- Tibia – the bone in front of the lower leg or shin bone.
- Patella – the thick, triangular bone at the top of the knee or kneecap.
A layer of cartilage covers the ends of the bones. This elastic, slick material absorbs shock and allows bones to glide against each other as they move.
Two crescent-shaped cartilage pads are located between the femur and tibia bones. They reduce friction and help to distribute the body’s weight across the joint. They are:
- The lateral meniscus is located at the outside of your knee.
- The medial meniscus is located on the inside of your knee.
A joint capsule holds the bones together and comprises two layers: an outer layer of dense connective tissues and an inner membrane called the synovium. This capsule secretes a fluid that lubricates the joint.
These ligaments and tendons that support the outer capsule at the ends of bones are:
- Quadriceps tendon that attach the quadriceps and patella
- The MCL or medial collateral ligament that provides stability for the inner knee
- The ACL or anterior cruciate ligament located in the middle of the knee and prevents forward movement of the tibia
- The PCL or posterior cruciate ligament found in the middle of the knee also prevents excessive backward movement of the knee
Two groups of muscles support the knee. These are:
- Hamstrings – The muscles at the back of your thigh that run from your hip to the knee.
- Quadriceps – These are the four muscles in front of the thigh, running from the hip to your knee. They straighten your knees from a bent position.
What is Cartilage?
Cartilage is a fibrous tissue that is extremely strong and flexible and serves many purposes in the body.
Hyaline cartilage, or articular cartilage, covers the bones’ surfaces, where they meet or articulate to form the joint. The articular cartilage covers the surfaces of bones at the joint.
Two primary functions of articular cartilage are:
- Smooth movement – The articular cartilage is extremely slippery and allows bones to glide across each other when a joint bends or straightens.
- Shock absorption—Articular cartilage acts like a shock absorber. Articular cartilage cushions bones from affecting each other when they are engaged in weight-bearing activities such as running or walking.
The synovial fluid is a sticky, viscous fluid that lubricates the joint and circulates nutrients. The fluid is stored within the articular cartilage when the joint is still at rest and is similar to water stored in a sponge.
The synovial fluid is sucked out when the joint supports weight or bends. This helps to keep the joints healthy and lubricated.
Chronic vs. Acute Pain
Pain is a sign that something is wrong. Acute pain quickly disappears with no cause, while chronic pain can last for six months or more and may not resolve until the injury or illness is treated.
People Who Are at Risk of Chronic Knee Pain
These are some factors that could increase your chances of developing osteoarthritis:
- Older people are more likely to develop knee osteoarthritis.
- Women are more susceptible to osteoarthritis.
- Obesity – Having more body weight can lead to osteoarthritis in many ways. The higher your weight, the greater the risk and the greater the need for weight loss. An increase in weight can cause stress to weight-bearing joints like your knees and hips. Fat tissue also produces proteins that can lead to inflammation around and in your joints.
- Joint injuries – Joint and knee injuries caused by playing sports or accidents can increase your risk of developing osteoarthritis. Even injuries like sprains that were not apparent to heal many years ago can increase your chances of developing osteoarthritis.
- Repetitive stress and sprains on the joints.
- Genetics – There is a genetic tendency for some people to develop osteoarthritis.
- Bone defects – Some people were born with deformed bones or damaged cartilage.
- Certain metabolic diseases, including diabetes and hemochromatosis, cause an iron deficiency.
It is challenging to treat arthritis because it is a complex disorder. You may not feel the need for treatment right away, as symptoms can change. This can lead to further complications later on.
Complications that can arise from arthritis include:
- Trouble sleeping
- Mobility issues
- Weight gain
- Anxiety and depression
Possible Causes of Chronic Knee Pain
Common causes of knee pain are:
Trauma – Injuries and Overuse
- Bursitis – Inflammation caused by repeated pressure on the knee, like overuse, prolonged kneeling, injury, or long periods of kneeling.
- Dislocation of the kneecap.
- Fracture of the kneecap and other bones.
- Iliotibial Band Syndrome – is Injuries to the thick band running from your hip to your outside knee.
- Torn ligament.
- Torn cartilage (a Meniscus tear) — Feels like a pain in the inner or outer knee joint.
- Strain — Injuries to the minor ligaments due to sudden or unnatural twisting.
Although it is not clear how obesity can affect rheumatoid and other forms of inflammatory arthritis, experts think that inflammatory chemicals from fat could play a part. RA is an autoimmune disease. This means your immune system attacks your body, particularly your joints. This causes inflammation and other problems in your body.
Injuries or Tendonitis
This condition is also known as tendonitis, inflammation, or irritation of a tendon. Tendons are connective tissue that exists between bones and muscles. Tendinitis can either be acute (short-term) or chronic (long-term).
Osgood-Schlatter’s disease is a common cause of knee pain in adolescents. It is an inflammation of the area below the knee where the tendon from the kneecap (patellar tendency) attaches to shinbones (tibia). Osgood-Schlatter diseases are most common during growth spurts when bones, muscles, and other structures change rapidly.
Children who engage in running or jumping sports, and put additional strain on their bones and muscles, are more at risk. This condition can also affect less active adolescents.
Patellofemoral Pain Syndrome
This condition is also known by the names jumper’s or runner’s knee. This medical condition causes pain below or around the kneecap (patella). PFPS can affect one or both of the knees. Both children and adults can be affected.
Most cases are triggered by activity, prolonged sitting with the knees bent, or prolonged periods of inactivity.
Gout is a prevalent type of inflammatory arthritis. Gout usually affects just one joint (often the big toe joint). Flares are when symptoms worsen, and remission is when they disappear entirely. Gout is a condition that cannot be treated. However, you can manage it with medication and self-management strategies.
Degenerative Tissue Disorder or Bacterial infection
Infectious arthritis refers to joint pain, stiffness, stiffness, and swelling caused by an infectious agent like bacteria, viruses, or fungi. Joint inflammation can occur when the infection has spread to the joint.
Often, this is accompanied by fever and chills. Depending on the infection type, one or more joints could be affected.
The knee is the most commonly affected joint by bacterial infections. After a viral infection or direct injury such as a bite, small joints such as the knee and fingers are more susceptible to becoming infected.
Intravenous drug users may have problems with the spine and breastbone (sternum). People with rheumatoid or other joint diseases are more vulnerable to developing infectious arthritis.
Auto-inflammatory Causes and Mechanical Problems
Degenerative or mechanical arthritis is a group of conditions that mainly affect the cartilage covering the ends of bones. The cartilage is essential for joint movement as it allows the joints to glide and move quickly.
This form of arthritis causes cartilage to become less dense and rougher. To repair the cartilage loss and improve joint function, the body starts to remodel bone, leading to osteoarthritis. Osteoarthritis may also be caused by previous joint damage, such as a fracture and previous inflammation.
Types of Arthritis and Other Problems
The CDC shows six significant types of arthritis: osteoarthritis (OA), rheumatoid arthritis (RA), fibromyalgia, childhood arthritis, gout, and lupus.
Different Symptoms to Take Note
A study by the American Association of Retired Persons (AARP) identifies the early signs of arthritis in knee joints.
- Joint swelling and tenderness happen as arthritis worsens, causing joints to become swollen and tender.
- Joint stiffness, especially in the morning, can occur after prolonged sitting, strenuous activity, or after a person wakes up.
- Grating sound or sensation as joints move is a sign the cartilage in one’s joint has worn down, resulting in arthritis.
- Pain in a joint previously injured may appear in a part of the body where there was a previous trauma or injury.
- Symmetrical joint pain due to rheumatoid arthritis often affects the same joints on both sides of the body, like both hands or knees.
Diagnosing Chronic Knee Pain
Fluid found in the knee may be visible above the kneecap or compressed there. A Baker’s cyst is a term that refers to this fluid that collects in the back of the knee.
Tests used to determine if a person has a meniscus tear include:
- Tenderness at the joint line – This is a non-specific test that can be used to diagnose a meniscus tear. A positive test indicates pain in the area of the meniscus.
- McMurray’s test – involves patients lying on their back with the examiner bending the knee. A click can be heard as the knee moves from full extension to full flexion.
- Ege’s Test – Ege is a test that involves the patient squatting. A click may be heard or felt where a meniscus tear is.
These tests may be done for a suspected anterior cruciate ligament (ACL) tear:
- Lachman test – This is the most reliable test for diagnosing test ACL tears. The examiner will bend the patient’s knee and stabilize their thigh while pulling the shin forward. The shin often shifts forward if the ACL is torn.
- Anterior drawer test– It can also be done with patients lying on their back. To check the stability and alignment of the ACL, the knee is bent 90°, and the shin is pulled forward.
- Pivot shift test – This is difficult to perform on patients experiencing discomfort or are unable to relax their knees because. The test puts stress on the knee joint to assess the ACL’s rotational stability.
Other Ligament Injuries
Tests can be performed if there is a suspicion of injury to any other ligaments (medial collateral ligament (MCL), posterior cruciate ligament(PCL), or lateral collateral ligaments (LCL).
The posterior drawer is similar to the anterior drawer. It is used to detect injury to the posterior cruciate ligament (PCL). The PCL’s function can also be tested by pushing the shin forward.
Collateral ligament stability test detects the lack of side-to-side stability at the knee and problems with the MCL or LCL.
The patient is lying flat on his back with the knee bent slightly. The shin is then shifted to the opposite side. The LCL or MCL can be damaged, which will cause the knee to “open up,” a problem known as varus (LCL) or valgus (MCL) instability.
Determining if one’s kneecap is in trouble involves the following tests:
Patellar grind – The patient lies flat on his back with one leg extended. The examiner then presses down on the patient’s kneecap and asks them to tighten their thigh muscles. Damaged cartilage can cause crepitus, a grinding sensation.
Patellar tenderness – An examiner lifts the kneecap slightly and applies pressure to specific subsurface areas. This allows the examiner to look for any areas of pain or sensitivity.
Patellar apprehension – The doctor checks for any sign of instability in the kneecap. The examiner may apply pressure to the kneecap in a specific direction. There is evidence of cartilage damage if the patient complains of the resulting sensation of “popping out” of its groove, causing the kneecap to feel strained.
Treating and Preventing Chronic Knee Pain
There are a number of approved treatments for chronic knee pain ranging from physical activity and lifestyle changes to pain management and even surgery when needed.
- Low-impact exercises such as low-impact aerobic workouts
- Activity modification
- Weight management
- Heat/ice packs
- Medications (prescribed or over-the-counter)
- Physical therapy
- Assistive devices
- Suitable footwear
Knee replacement surgery, also called knee arthroplasty (ARTHROW-plas-tee), may help with pain relief and return function to severely damaged knee joints. This involves removing damaged bone and cartilage, from your kneecap, shinbone, and thighbone.
Then, a surgeon replaces it with an artificial joint (prosthesis), made of high-grade metal alloys, plastics, and polymers.
An orthopaedic or orthopedic surgeon will assess your knee’s strength, range of motion and stability to determine if a knee replacement is a right treatment option for you. The extent of the damage can be determined by X-rays, a CT scan, or at times a MRI.
When to See a Doctor
See your doctor if an especially strong impact causes your knee pain, or if you have:
- Significant swelling
- Warmth and tenderness around the joint
- Significant pain
If you have had mild knee pain for some time and it worsens to interfere with activity or sleep, make an appointment with your doctor and ask for treatment options.
What Is the Extended Outlook for Chronic Knee Pain?
New treatments, non-invasive surgeries, and developments in physical therapy mean the prospect of a full recovery from chronic knee pain is brighter every day.
How Do I Know If My Knee Pain Is Serious?
Knee pain that persists beyond six months is a sign you should find an orthopedic specialist.
Is Chronic Knee Pain Curable?
Though not always curable, the lingering effects of chronic knee pain can be successfully treated in many ways.
Could My Knee Pain Be Arthritis?
Yes, it could.
There are over 100 types of arthritis that may cause knee problems. It is recommended that people with chronic knee pain see their doctors for a physical examination or other tests for an accurate diagnosis.