Knee Osteoarthritis: Causes, Symptoms, and Evidence-Based Treatments
Knee osteoarthritis (OA) is one of the most common causes of knee pain, particularly in individuals over 50, but it can also affect younger adults. This condition occurs when the protective cartilage that cushions the knee joint breaks down over time, leading to pain, swelling, stiffness, and loss of mobility. While knee OA is often associated with aging, it can also be precipitated by other factors such as previous injuries, obesity, and certain repetitive activities. In this blog, we’ll explore the pathophysiology, causes, symptoms, and evidence-based treatments for knee osteoarthritis, with a focus on non-surgical options like physical therapy and lifestyle modifications.
What is Knee Osteoarthritis?
Knee osteoarthritis is a degenerative joint disease characterized by the progressive breakdown of cartilage within the knee joint. The knee joint is made up of three bones: the femur (thigh bone), tibia (shin bone), and patella (kneecap). These bones are covered by cartilage, which provides a smooth surface for movement and acts as a shock absorber. In knee osteoarthritis, the cartilage begins to wear away, leading to pain, inflammation, and decreased joint function.
As the cartilage deteriorates, the bones in the joint may start to rub against each other, causing pain and swelling. In advanced stages of OA, the bone may also develop bony growths called osteophytes, which can further restrict movement and contribute to joint instability.
Pathophysiology of Knee Osteoarthritis
Knee OA develops due to an imbalance in the normal processes of cartilage breakdown and repair. Under normal circumstances, the cartilage in a healthy knee joint is constantly being remodeled. However, in osteoarthritis, the rate of cartilage degradation outpaces the rate of repair. This results in the thinning of the cartilage and, eventually, the loss of the joint's protective cushion.
Cartilage Degeneration: In knee OA, the articular cartilage, which provides cushioning and allows smooth movement of the knee joint, begins to break down. This leads to reduced shock absorption and friction between the bones.
Synovial Inflammation: The synovium, a tissue lining the joint capsule, can become inflamed in response to cartilage damage. This inflammation further contributes to pain, swelling, and stiffness in the knee joint.
Bone Changes: As the cartilage breaks down, the underlying bone may become exposed and thicken, a process known as subchondral sclerosis. Bone spurs (osteophytes) may also form at the joint margins, which can restrict joint movement and cause additional discomfort.
Loss of Joint Function: Over time, knee OA can lead to joint instability, limited range of motion, and difficulty with weight-bearing activities, such as walking, climbing stairs, or squatting.
Causes and Risk Factors for Knee Osteoarthritis
Knee OA can be caused by a combination of factors, and some individuals may have multiple contributing factors that increase their risk. The most common causes and risk factors include:
Age: The risk of developing knee OA increases with age. As people get older, the cartilage in the joints naturally wears down, making the knee more vulnerable to OA.
Previous Injury: Past knee injuries, such as ligament tears, fractures, or meniscus tears, can increase the risk of developing OA later in life. Even injuries that heal properly may leave the joint weakened or altered, leading to wear on the cartilage over time.
Obesity: Excess body weight puts added stress on weight-bearing joints like the knees. This increases the risk of cartilage breakdown and the development of OA. Research has shown that for each extra pound of body weight, the knee bears an additional 3-5 pounds of pressure with every step.
Genetics: A family history of knee OA or other joint conditions may increase the likelihood of developing knee OA. Certain genetic factors can predispose individuals to cartilage degeneration.
Occupation and Activity Level: Jobs or activities that involve repetitive knee movements or prolonged kneeling, squatting, or heavy lifting can increase the risk of developing knee OA. Athletes who participate in high-impact sports may also be at greater risk.
Gender: Women are more likely than men to develop knee OA, particularly after menopause. Hormonal changes and other factors may contribute to this increased risk.
Abnormal Joint Alignment: Conditions like knocked knees (genu valgum) or bow-leggedness (genu varum) can alter the distribution of forces across the knee joint, increasing the risk of OA in certain areas of the knee.
Symptoms of Knee Osteoarthritis
Knee osteoarthritis typically develops gradually, and symptoms may worsen over time. Common symptoms include:
Knee Pain: The most obvious symptom of knee OA is pain, which is often felt during or after activity, especially weight-bearing activities like walking, running, or climbing stairs. The pain can be sharp or aching and may worsen with prolonged standing or movement.
Stiffness: People with knee OA often experience stiffness in the knee joint, particularly after periods of inactivity, such as sitting for long periods or in the morning upon waking. Stiffness can make it difficult to fully extend or bend the knee.
Swelling: Inflammation in the knee joint may lead to swelling. The knee may feel tender and warm to the touch, and the joint may appear swollen, especially after physical activity.
Grinding or Crepitus: A sensation of grinding or clicking may be felt in the knee joint when moving. This occurs due to the rubbing of the bones as the cartilage wears away.
Limited Range of Motion: Over time, knee OA can lead to a reduced range of motion, making it difficult to perform basic activities like walking or squatting.
Evidence-Based Treatments for Knee Osteoarthritis
While knee osteoarthritis is a progressive condition, there are several evidence-based treatments available that can help manage symptoms, improve joint function, and slow the progression of the disease. The goal of treatment is to reduce pain, improve mobility, and enhance quality of life. Some of the most effective treatments include:
1. Physical Therapy
Physical therapy is one of the most effective treatments for knee OA. Evidence supports that strengthening the muscles around the knee, improving flexibility, and correcting movement patterns can reduce the stress on the joint and improve overall function. A study published in Arthritis Care & Research found that physical therapy interventions, including strength training, flexibility exercises, and joint mobilizations, can significantly reduce pain and improve knee function in individuals with OA.
Strengthening Exercises: Targeted exercises to strengthen the quadriceps, hamstrings, and calf muscles can provide better support to the knee joint, reducing the load on the cartilage and improving stability.
Stretching and Mobilization: Stretching tight muscles, particularly the hamstrings and calves, can improve flexibility and reduce stress on the knee joint. Manual therapy techniques, such as joint mobilizations, can also help alleviate stiffness and pain.
Biomechanical Training: Teaching proper movement techniques and posture during walking, running, and other activities can help reduce excessive strain on the knee joint.
Dry Needling: Dry needling for knee osteoarthritis can be very successful in reducing pain and tightness around the knee joint and surrounding muscles. Learn more about dry needling here.
2. Weight Management
Losing excess weight is one of the most important ways to reduce the stress placed on the knees and slow the progression of OA. Studies show that even a modest weight loss can have a significant impact on pain and function in individuals with knee OA. Reducing body weight helps decrease joint load, particularly during weight-bearing activities.
We often see clients in a tough spot where they want to lose weight, but exercise is too painful to do that! This is a perfect scenario for a Physical Therapist to help! We can create custom strength and rehab programs to help you lose weight and build strength without worsening knee pain.
3. Pain Management
For acute pain, over-the-counter pain medications like NSAIDs (ibuprofen) or acetaminophen can help reduce inflammation and provide short-term relief. For more severe pain, corticosteroid injections directly into the knee joint may provide temporary relief. Hyaluronic acid injections may also be used to provide lubrication and reduce pain in the joint.
4. Surgical Treatment
In advanced cases where conservative treatments are no longer effective, surgery may be necessary. These should be considered as a last resort after extensive and comprehensive conservative treatments have been exhausted. Options include:
Knee Arthroscopy: A minimally invasive procedure in which the surgeon removes damaged tissue from the knee joint.
Osteotomy: A procedure to realign the knee joint, often used for individuals with misaligned joints.
Total Knee Replacement: In severe cases, a knee replacement surgery may be necessary to replace the damaged knee joint with a prosthetic.
Conclusion
Knee osteoarthritis is a common condition that can affect individuals of all ages, particularly as they age. However, it is important to understand that lifestyle modifications, such as physical therapy, weight management, and proper pain management, can significantly reduce symptoms and improve knee function. Early intervention is key to slowing the progression of the disease and maintaining an active lifestyle. If you are struggling with knee pain, consider consulting with a physical therapist who can help you develop a personalized treatment plan to improve your mobility and reduce pain.
At Wildflower Physical Therapy & Wellness in Indianapolis, we specialize in treating knee osteoarthritis with a personalized, evidence-based approach. Our team of experts will work with you to develop a customized treatment plan to manage your knee pain and restore function. Contact us today to schedule an appointment!
If you are struggling with illness or injury and would like to get your body moving, schedule a physical therapy appointment with us today! At Wildflower Physical Therapy & Wellness, we can help you to get back to the life you want to live through pain management strategies, activity promotion and exercise. Our Cash Based Physical Therapy model allows us to deliver a highly individualized treatment plan without the fuss of insurance companies. Interested in trying dry needling to support your exercise routine and maximize recovery? Reach out to us today!