Bilateral knee pain, discomfort in both knees simultaneously, is a common symptom. Understanding its causes is the first step toward effective relief. This overview explores common causes, from mechanical issues to systemic diseases.
Overuse and Biomechanical Factors
Repetitive actions and body mechanics issues often lead to pain in both knees. Patellofemoral pain syndrome, or “runner’s knee,” commonly affects both knees due to symmetrical stress. This syndrome involves pain around or behind the kneecap, worsening with activities like squatting, climbing stairs, or prolonged sitting with bent knees. The kneecap may not track smoothly, leading to irritation.
Overuse from activities like running or jumping can strain both knee joints. Repetitive loading without sufficient rest can cause microtrauma to muscles, tendons, cartilage, or bone. Muscle imbalances (e.g., weaker quadriceps or tighter hamstrings) can place excessive strain on both knee joints. These imbalances alter how the knee absorbs shock, leading to conditions like patellar tendonitis or iliotibial band syndrome.
Types of Arthritis Affecting Both Knees
Arthritis is a common cause of bilateral knee pain, with several types impacting both joints. Osteoarthritis (OA), or “wear-and-tear” arthritis, is a degenerative condition where knee cartilage gradually breaks down. This thinning and roughening causes bones to rub, leading to pain, stiffness, and swelling that often worsens with activity and improves with rest. Bilateral knee OA is very common, and many individuals with OA in one knee eventually develop it in the other due to shared biomechanical stresses.
Rheumatoid arthritis (RA) is an autoimmune disease where the immune system attacks the body’s own tissues, including the synovial membrane lining the joints. This leads to inflammation, pain, and stiffness, typically affecting the same joints on both sides, including the knees. Symptoms include pain, swelling, and difficulty bending or straightening the knee, often accompanied by fatigue and fever.
Psoriatic arthritis is an autoimmune condition linked to psoriasis, a skin disorder. It causes joint pain, swelling, and stiffness, and may affect both knees. The immune system attacks healthy joint tissue, similar to rheumatoid arthritis.
Gout is an inflammatory arthritis caused by the accumulation of uric acid crystals in a joint. While it most commonly affects the big toe, it can also manifest in the knees and, over time, affect multiple joints, potentially leading to bilateral knee pain. These crystal deposits trigger sudden, severe pain, swelling, redness, and warmth in the affected joint.
Systemic Conditions as a Cause
Systemic conditions affecting the body can manifest as bilateral knee pain, often as part of wider symptoms. Systemic lupus erythematosus (lupus) is an autoimmune disease that causes joint pain and inflammation throughout the body, including the knees. Nearly 90% of individuals with lupus experience joint pain, which may be symmetrical and affect multiple joints.
Fibromyalgia is a chronic condition with widespread musculoskeletal pain, including in the knees, often accompanied by fatigue and sleep disturbances. The knee pain in fibromyalgia stems from how the central nervous system processes pain signals, amplifying sensations even without visible joint damage.
Infections can lead to joint pain, known as infectious or septic arthritis. While typically affecting a single joint, a systemic infection can sometimes spread to multiple joints, including both knees. Symptoms usually appear rapidly and include intense swelling, pain, redness, warmth, and fever.
When to Seek Medical Attention
Seek medical evaluation for persistent or worsening knee pain. Consult a healthcare provider if your pain does not improve within a few weeks or interferes with daily activities or sleep.
Immediate medical attention is necessary for marked knee swelling, redness, warmth to the touch, or an inability to bear weight on your knee. Other concerning signs include an inability to fully extend or flex the knee, a “popping” sound at the time of injury, or if the knee feels unstable or gives out. A fever accompanying knee pain, or other systemic symptoms like unexplained weight loss or fatigue, warrants prompt medical evaluation as these could indicate an underlying illness.