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 thumbs), spine (neck and lower back), knees and hips
  • Less commonly affects the elbow, wrist, shoulder and ankle
• 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; more prevalent and affects not only individuals with advanced age but also younger persons
  • 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, dislocation, sibluxation, malunion), complication of an inflammatory disorder (septic arthritis, ankylosing spondylitis, rheumatoid arthritis, rotator cuff arthropathy and psoriatic arthritis), or medications (corticosteroid therapy, cytotoxic drugs)

Epidemiology

• Approximately 3.8% worldwide incidence of knee OA, increasing with age to >10% in individuals >60 years old
• Shoulder OA is more common in women and most commonly seen in patients >50 years of age
  • More commonly affects the acromioclavicular joint than the glenohumeral shoulder joint

• 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