Osteoarthritis Signs and Symptoms

• A clinical syndrome of joint pain with different degrees of limitation in function and decreased quality of life
• Most common form of arthritis
• Leading cause of disability of the lower extremity in older adults
• May not be secondary to aging and does not automatically progress
• Most often occurs in the hands (ends of the fingers and thumb), spine (neck and lower back), knees and hips
• Classified as primary or secondary based on the cause or major predisposing factor; both have altered cartilage physiology
  • Primary osteoarthritis (OA) is the most common with no known cause
  • Secondary OA has identifiable etiology but pathologically similar to primary OA
    • Common causes are metabolic diseases (eg hemochromatosis, acromegaly), anatomic causes (eg developmental hip dislocation), trauma (joint surgery, intra-articular fractures, ligament or meniscus damage, malunion), or complication of an inflammatory disorder (septic arthritis, ankylosing spondylitis, rheumatoid arthritis and psoriatic arthritis)

Epidemiology

• Approximately 3.8% worldwide incidence of knee OA, increasing with age to >10% in individuals >60 years old
• Glenohumeral OA is more common in women and most commonly seen in patients >60 years of age

• Process of progressive softening or localizing loss of cartilage accompanied by remodelling of adjacent bone and inadequate metabolic repair resulting in structural joint changes which cause pain and functional disability

• Cardinal features of OA are pain, stiffness, decreased movement, inflammation, crepitus and absence of systemic signs and symptoms like fever
  • OA pain is usually aggravated by activities and relieved by rest; not common to occur at night or during rest but may be experienced by patients after several hours of using joints, in advanced OA and in acute inflammatory flare
  • Stiffness occurs in the morning lasting for a few minutes but <30 minutes, after period of rest, or in the evening which usually resolves within 10 minutes of activity

Age

• >80% of individuals older than 75 years are affected; not common in patients <40 years old unless with history of trauma

Female Gender

• Higher risk for knee OA after menopause for unclear reasons but may be related to hormones, genetics or other undetermined factors

Genetic Predisposition

• The influence of genetic factor varies in different subsets of OA, ranging from 40-70%

Obesity

• Increases risk for symptomatic and progressive OA 
  • Increases the risk for knee OA due to the increased mechanical stress on the joints and altered joint biomechanics secondary to changes in posture, gait and level of physical activity
  • Increases stiffness in the subchondral bones and facilitates cartilage breakdown

Joint Trauma or Malalignment

• Results in rapid development of OA or starts the process causing symptomatic OA later in life
• Selected occupational usage and repetitive, high-impact sports are strongly related to joint injury which increases the risk for lower extremity OA