Experiencing pain in both knees simultaneously, known as bilateral knee pain, is a common concern. Unlike unilateral pain, which often points toward an acute injury or trauma, bilateral discomfort frequently indicates a chronic or systemic issue. This symmetrical presentation suggests a condition affecting the entire body or a widespread mechanical problem impacting both joints equally. Understanding the potential causes is the first step in finding appropriate relief and management.
Degenerative Causes: Osteoarthritis
The most frequent cause of bilateral knee pain, especially in older adults, is osteoarthritis (OA), which is often described as a “wear-and-tear” condition. This degenerative process involves the gradual breakdown of articular cartilage, the smooth, protective tissue that cushions the ends of the bones in the joint. As the cartilage erodes, it loses its ability to reduce friction, leading to bone-on-bone contact and subsequent pain. This mechanical deterioration results in characteristic symptoms that worsen predictably with activity and weight-bearing. Pain is typically aggravated by standing, walking, or prolonged activity, and generally lessens with rest. Stiffness is also a common feature, particularly after periods of rest, such as first thing in the morning or after sitting for a long time. A distinguishing factor of OA-related stiffness is its duration, which usually lasts less than 30 minutes before improving with movement. Many individuals also experience crepitus, a grating, clicking, or cracking sensation in the joint. Several factors contribute to the development of bilateral OA, including advanced age, a history of previous knee injury, and obesity, which increases the mechanical load on the joint.
Inflammatory and Systemic Conditions
When both knees hurt, the cause may be a systemic condition where the body’s immune system mistakenly attacks multiple joints, leading to widespread inflammation. These autoimmune disorders often present symmetrically, affecting the same joints on both sides of the body. The inflammation in these conditions involves the synovial membrane, the tissue lining the joint, which becomes thickened and swollen.
Rheumatoid Arthritis (RA)
RA is a primary example where the immune system attacks the joint lining, causing pain, warmth, and swelling in both knees. A hallmark symptom of RA that differentiates it from OA is the duration of morning stiffness, which typically lasts for more than one hour. Furthermore, the pain from RA may be worse at rest or after prolonged inactivity, rather than only after weight-bearing activity.
Psoriatic Arthritis (PsA)
PsA is an inflammatory condition linked to the skin disorder psoriasis. It can present in a polyarticular symmetric pattern, causing pain, swelling, and reduced range of motion in both knees. A unique feature of PsA is enthesitis, which is the inflammation that occurs where tendons or ligaments attach to the bone. This often manifests as pain at the heel or sole of the foot alongside the knee symptoms.
Gout
Gout classically affects a single joint, such as the big toe, but can also infrequently cause bilateral knee pain when uric acid crystals build up in the joint fluid. This results in episodes of intense pain, warmth, and significant redness around the joint. All of these systemic conditions are characterized by a pronounced inflammatory response, which is often indicated by elevated markers like C-reactive protein in blood tests.
Biomechanical Issues and Overuse Syndromes
Bilateral knee pain can also stem from issues related to body alignment and repetitive stress, which commonly affect both knees due to shared movement patterns. These mechanical problems are particularly prevalent in physically active individuals, such as runners, or those with underlying muscular imbalances.
Patellofemoral Pain Syndrome (PFS)
PFS, also known as “runner’s knee,” is a frequent cause of bilateral pain originating from the joint between the kneecap (patella) and the thigh bone (femur). The pain is caused by the kneecap tracking incorrectly within its groove as the knee bends and straightens, often due to weakness or imbalance in the quadriceps and hip muscles. This poor tracking leads to a dull, aching pain behind or around the kneecap that is notably aggravated by activities that load a bent knee. Common pain triggers for PFS include climbing or descending stairs, squatting, and sitting for extended periods with the knees bent.
Overuse Tendonitis
Overuse can also lead to bilateral tendonitis, which involves irritation and inflammation of the tendons, such as the patellar or quadriceps tendons. This type of pain often results from a sudden increase in the intensity or duration of a physical activity, causing localized tenderness and pain that worsens with movement.
Recognizing Urgent Symptoms and Next Steps
While many causes of bilateral knee pain are chronic and manageable with time, certain symptoms require immediate medical attention to rule out severe injury or infection.
Urgent Symptoms
A sudden, severe swelling of the joint, an inability to bear any weight on the leg, or a noticeable deformity in the knee joint are symptoms requiring immediate attention. Any joint pain accompanied by a fever, chills, or significant warmth and redness around the knee could indicate a joint infection, which is a medical emergency.
Next Steps
For less acute pain, initial self-management can help ease discomfort before a professional evaluation. Applying ice to the affected area for 15 to 20 minutes every few hours can help reduce inflammation. Using over-the-counter pain relievers, such as topical creams or gels, can also provide temporary relief. If the pain persists for more than a few days, significantly limits daily activities, or returns frequently, consulting a healthcare professional is advisable to determine the exact cause and develop a targeted management plan.