Overview
Knee pain is one of the most common musculoskeletal complaints. It has many causes, ranging from acute injuries such as ligament tears and meniscal damage to chronic conditions like osteoarthritis and patellofemoral pain. Most knee pain responds to conservative management, though some injuries require surgical intervention.
How common is it?
Knee pain affects all age groups. Patellofemoral pain (anterior knee pain) is the most common diagnosis in young active people. Osteoarthritis of the knee affects around 25% of people over 55 and is a leading cause of disability.
Causes and risk factors
Acute knee pain usually follows injury to ligaments, menisci, or bone. Chronic knee pain commonly reflects overuse, degeneration, or inflammatory arthritis.
Common risk factors
- Osteoarthritis (age-related cartilage degeneration)
- ACL, PCL, MCL, or LCL ligament tears (sports or trauma)
- Meniscal tears
- Patellofemoral pain syndrome (runner's knee)
- Iliotibial band syndrome
- Patellar tendinopathy (jumper's knee)
- Bursitis (prepatellar, infrapatellar)
- Gout or pseudogout (crystal arthropathy)
- Rheumatoid or psoriatic arthritis
- Osgood-Schlatter disease (teenagers)
Symptoms
- Pain localised to the front, inside, outside, or back of the knee depending on cause
- Swelling with effusion (fluid)
- Stiffness, especially in the morning or after rest
- Giving way or instability (ligament injuries)
- Locking or catching (meniscal tear)
- Crepitus (grinding or clicking)
When to see a doctor
Seek assessment for significant trauma with swelling, instability, or inability to weight-bear. Also seek review for knee pain lasting more than 6 weeks, or for hot, swollen joints with fever (possible septic arthritis, a medical emergency).
Diagnosis
Clinical examination including special tests (Lachman, McMurray, valgus/varus stress). X-ray for osteoarthritis and fracture. MRI for soft tissue injuries (ligaments, menisci, cartilage). Aspiration and synovial fluid analysis if infection or crystal arthropathy suspected.
Treatments
Physiotherapy
Vastus medialis and quadriceps strengthening, hip abductor strengthening, and gait correction are highly effective for patellofemoral pain and osteoarthritis. Core and gluteal strengthening reduces abnormal knee loading.
NSAIDs and analgesia
Topical diclofenac gel is effective and preferred over oral NSAIDs for osteoarthritis (lower systemic side effects). Paracetamol has modest benefit.
Intra-articular corticosteroid injection
Provides significant short-term pain relief in osteoarthritis and inflammatory arthritis. Effects last weeks to months.
Surgical options
ACL reconstruction for symptomatic instability. Meniscal repair or partial meniscectomy. Total or partial knee replacement for end-stage osteoarthritis is one of the most successful elective operations in medicine.
Self-care and lifestyle
- Maintain a healthy weight (each kilogram lost reduces knee load by 4 kg)
- Strengthen the quadriceps and hip muscles regularly
- Avoid activities that repeatedly aggravate the knee while maintaining overall fitness (cycling, swimming)
- Wear well-fitting supportive footwear for daily activities and sports
Prevention
Maintaining quadriceps and hip strength, managing body weight, and avoiding sudden increases in exercise intensity reduce knee injury and osteoarthritis risk.