What are the signs, symptoms, and management options for osteoarthritis (OA) of the knee?

Signs and Symptoms of Osteoarthritis of the Knee

Knee osteoarthritis (OA) is characterized primarily by joint pain, stiffness, and functional limitations, with symptoms typically worsening gradually over time and increasing with joint use. 1

Primary Clinical Manifestations

Pain Characteristics

• Pain is typically mechanical in nature, worsening with activity and improving with rest in early stages 2
• As disease progresses, pain may become more constant and occur at rest or at night 3
• Pain is often localized to the affected compartment of the knee (commonly medial joint line tenderness) 1
• Pain severity often does not correlate well with radiographic findings 2

Joint Function Limitations

• Morning stiffness typically lasting less than 30 minutes 1
• Difficulty with purposeful movement, especially weight-bearing activities 1
• Decreased range of motion as the condition progresses 1
• Coarse crepitus (crackling or grating sensation) during joint movement 3

Physical Examination Findings

• Joint line tenderness, particularly at the medial compartment 1
• Bony enlargement around the joint margins due to osteophyte formation 3
• Joint effusion (swelling) of varying severity 1
• Decreased range of motion compared to unaffected knee 1
• Antalgic gait pattern (limping to avoid pain) 1

Risk Factors and Demographics

• Increasing age is the strongest risk factor, with prevalence rising significantly after age 55 1
• Women are more commonly affected than men, representing 78% of diagnosed cases 1
• Obesity significantly increases risk and worsens symptoms 1
• Prior knee trauma or surgery increases risk of developing OA 1
• Genetic predisposition plays a significant role, with heritability estimates of 39-65% 1
• Certain occupations requiring repetitive knee stress increase risk 1

Disease Impact and Progression

• Symptoms typically worsen gradually over years 2
• Functional limitations lead to decreased physical activity and quality of life 3
• Advanced cases may present with joint deformity and malalignment 3
• Risk of disability from knee OA equals that from cardiac disease and exceeds other medical disorders in the elderly 1
• Approximately 10% of people over 55 years experience disabling knee symptoms, with a quarter being severely disabled 1

Pathophysiological Changes

• Focal loss of articular cartilage and marginal/central new bone formation 1
• Decreased concentration and viscosity of synovial fluid, reducing lubricating properties 4
• Underlying synovial inflammation and subchondral bone damage 4
• Imbalance between cartilage destruction and synthesis processes 4

Management Considerations

• Exercise programs (both strength training and aerobic) are strongly recommended to reduce pain and improve function 1, 5
• Weight loss is strongly recommended for overweight patients 1, 5
• Pharmacological options include acetaminophen, topical and oral NSAIDs, and intra-articular corticosteroid injections 1
• Joint replacement should be considered for refractory pain associated with disability and radiological deterioration 1
• Self-management education programs can help reduce pain and increase coping skills 1, 5

Common Pitfalls in Assessment

• Relying solely on radiographic findings for diagnosis or treatment decisions (poor correlation with symptoms) 2
• Failing to assess impact on function and quality of life 3
• Not considering mechanical factors such as alignment and muscle weakness 1
• Overlooking the multifactorial nature of pain in knee OA 2
• Inadequate evaluation of other potential causes of knee pain 1

Understanding these signs and symptoms is essential for proper diagnosis and developing an effective management plan that addresses both symptom control and potential disease modification.