Osteoarthritis for the Physician Assistant Licensing Exam

Overview of Osteoarthritis (OA)

Definition: OA is a chronic, degenerative joint disease causing cartilage deterioration, subchondral bone changes, pain, and decreased function.

Pathophysiology

Cartilage Degradation: Mechanical stress and biochemical changes result in thinning of cartilage.
Bone Changes: Subchondral sclerosis and osteophyte formation occur as the cartilage wears away, contributing to pain and joint stiffness.
Low-Grade Inflammation: Synovitis may be present but less significant than in inflammatory arthritis like rheumatoid arthritis.

Risk Factors

Age: Incidence increases significantly with advancing age.
Obesity: Major risk factor, especially for knee OA, due to increased joint stress.
Gender: Women are more likely to develop OA, particularly after menopause.
Joint Injury or Overuse: History of trauma, repetitive joint use, or occupation-related joint stress.
Genetics and Family History: Hand OA is particularly associated with genetic predisposition.

Symptoms and Signs

Joint Pain: Worsens with activity and improves with rest; often asymmetric.
Morning Stiffness: Brief, typically lasting less than 30 minutes, improves with movement.
Crepitus: Audible or palpable grinding sensation with joint movement.
Deformities and Limited Range of Motion: Advanced OA can lead to visible joint deformities and functional limitations.
Commonly Affected Joints: Knees, hips, hands (DIP, PIP, and thumb base), and spine.

Diagnosis

Clinical Diagnosis: Based on characteristic joint pain, physical examination, and risk factors.
Imaging Studies:

X-ray: Key features include joint space narrowing, osteophytes, subchondral sclerosis, and subchondral cysts.

Laboratory Tests: Generally normal; used primarily to rule out other types of arthritis like rheumatoid arthritis.

Management

Exercise: Focus on low-impact activities, muscle strengthening, and range-of-motion exercises.
Weight Management: Crucial in reducing symptoms, particularly for weight-bearing joints.
Assistive Devices: Braces, orthoses, and canes for support and pain relief.

Acetaminophen: First-line for mild to moderate pain.
NSAIDs: For moderate to severe pain or inadequate response to acetaminophen; available orally or topically.
Topical Treatments: Capsaicin and topical NSAIDs for localized pain.
Intra-Articular Corticosteroids: For acute flare-ups and symptom control in advanced OA.

Surgical Interventions: Consider joint replacement or arthroplasty in cases of severe, refractory OA.

Essential Points

Early Diagnosis and Treatment: Timely intervention with non-pharmacologic strategies can delay progression.
Symptom Management: Focus on pain relief, improving joint function, and enhancing quality of life.
Individualized Therapy: Treatment tailored to joint involvement, severity of symptoms, and patient preferences.
Multimodal Approach: Combining lifestyle changes, pharmacotherapy, and physical interventions yields optimal outcomes.