Osteoarthritis of the Knees: Clinical Presentation and Risk Factors

Clinical Presentation

• The American Academy of Orthopaedic Surgeons recommends recognizing joint pain that worsens with activity, morning stiffness lasting less than 30 minutes, limited range of motion, and difficulty with purposeful movement as primary signs and symptoms of knee osteoarthritis 1
• Pain during usage is a common feature, though it has limited diagnostic value (high specificity but low sensitivity), according to the European League Against Rheumatism 2
• Morning or inactivity stiffness is typically mild and of limited duration (less than 30 minutes), as stated by the American Geriatrics Society and the American Academy of Orthopaedic Surgeons 3, 4
• Difficulty with purposeful movement, particularly weight-bearing activities, is a common functional limitation, according to the American Academy of Orthopaedic Surgeons 1
• Reduced ability to perform daily activities is a significant functional impairment, as reported by the American Geriatrics Society 4
• Functional impairment may be as severe as in rheumatoid arthritis, according to the European League Against Rheumatism 5
• Decreased mobility and walking distance are common consequences of osteoarthritis, as stated by the American Geriatrics Society 4
• Limited range of motion is a characteristic physical examination finding, according to the American Academy of Orthopaedic Surgeons 3
• Muscle weakness, particularly of the quadriceps, is a significant factor in symptom severity and functional limitations, as reported by the American Academy of Orthopaedic Surgeons and the European League Against Rheumatism 3, 5

Risk Factors and Associations

• Female sex (women represent 78% of diagnosed cases) is a significant risk factor, according to the American Academy of Orthopaedic Surgeons 1
• Increasing age, especially over 40 years, is a major risk factor, as stated by the American Academy of Orthopaedic Surgeons and the European League Against Rheumatism 1, 2
• Obesity (BMI >25) is a significant risk factor, according to the American Academy of Orthopaedic Surgeons 6
• Prior joint injury or trauma is a risk factor, as reported by the European League Against Rheumatism 2
• Occupation or recreation-related joint usage is a risk factor, according to the European League Against Rheumatism 2
• Family history of osteoarthritis is a risk factor, as stated by the European League Against Rheumatism 2
• Presence of osteoarthritis in other joints (particularly hands) is a risk factor, according to the European League Against Rheumatism 5

Impact on Quality of Life

• Increased healthcare utilization (older adults with OA visit physicians more frequently) is a common consequence, according to the American Academy of Orthopaedic Surgeons 1

Common Pitfalls in Assessment

• Failure to distinguish mechanical knee pain of OA from inflammatory or other causes of knee pain is a common pitfall, as reported by the European League Against Rheumatism 2
• Overlooking the impact of muscle weakness on symptom severity and functional limitations is a significant pitfall, according to the American Academy of Orthopaedic Surgeons 3
• Symptoms may be attributed to normal aging rather than recognized as a treatable condition, as stated by the American Academy of Orthopaedic Surgeons 1