Osteoarthritis Overview (causes, pathophysiology, investigations, treatment)

Summary

This video provides an in-depth overview of osteoarthritis, focusing primarily on the knee joint. It explains the anatomy of synovial joints, discusses the degeneration of articular cartilage, and details how osteoarthritis progresses. Risk factors such as age, obesity, and joint injuries are highlighted, along with symptoms like pain, stiffness, and joint malalignment. The video also covers pathophysiology, including immune cell activation and inflammation, diagnostic techniques like joint aspiration, and various management strategies ranging from non-pharmacological approaches to surgery.

Takeaways

• 🦴 Osteoarthritis (OA) commonly affects the knee joint, causing degeneration of articular cartilage, joint space narrowing, and bone spurs (osteophytes).
• 🦠 The knee joint is a synovial joint surrounded by the synovial membrane, which produces synovial fluid to lubricate and nourish the joint.
• ⚖️ Risk factors for osteoarthritis include age, obesity, previous joint injuries, leg deformities (e.g., bow legs or knock knees), and genetics.
• 🤕 Primary osteoarthritis is age-related with no preceding injury, while secondary osteoarthritis occurs due to trauma, congenital abnormalities, or inflammatory diseases.
• 🔄 The disease progresses from mild cartilage degeneration to severe bone-on-bone contact and joint deformity, often resulting in pain and reduced mobility.
• 🧠 Pain in osteoarthritis can vary widely among individuals, influenced by cytokines like prostaglandins and bradykinin, which activate pain receptors.
• 💉 Joint aspiration (arthrocentesis) is a diagnostic tool used to differentiate osteoarthritis from other joint conditions like gout or septic arthritis.
• 💊 Non-pharmacological treatments include weight loss, physiotherapy, using knee braces or walking aids, and heat or cold therapy.
• 💉 Pharmacological treatments range from paracetamol and topical NSAIDs to corticosteroid injections and, in severe cases, opioids.
• 🦿 Surgical interventions, such as total knee replacement, are considered the last resort when conservative treatments fail to alleviate pain and improve mobility.

Q & A

What is osteoarthritis, and why is it common in the knee joint?

Osteoarthritis is a degenerative joint disease characterized by the breakdown of articular cartilage. It is common in the knee joint because the knee is a weight-bearing joint, which is susceptible to wear and tear over time.

What are the key structures of a synovial joint, particularly in the knee?

The key structures of a synovial joint include bones surrounded by periosteum, articular cartilage, synovial membrane, synovial fluid, fibrous capsule (forming the articular capsule), and stabilizing ligaments. In the knee, there is also a fibrocartilage called meniscus, which aids in joint stability and shock absorption.

What are the main risk factors for developing osteoarthritis?

The main risk factors for osteoarthritis include aging, being female (especially for hip joints), obesity, previous joint injuries, malalignment such as bow legs or knock knees, rheumatic diseases, and genetics.

How does osteoarthritis progress, and what are the differences between mild and severe osteoarthritis?

Osteoarthritis progression can be slow or fast. Mild osteoarthritis involves the breakdown of articular cartilage and joint space narrowing. Severe osteoarthritis is characterized by bone-on-bone contact, complete loss of cartilage, and the formation of bone spurs (osteophytes).

What is the difference between primary and secondary osteoarthritis?

Primary osteoarthritis is idiopathic, meaning it occurs without a known cause, typically due to aging and degeneration. Secondary osteoarthritis is caused by another condition, such as trauma, congenital abnormalities, or inflammatory arthritis.

What are the common clinical symptoms of osteoarthritis?

Common symptoms include joint pain, which worsens with exercise and is relieved by rest, stiffness, reduced joint movement, muscle wasting, joint malalignment, tenderness, and sometimes crepitus. In severe cases, pain can occur at rest or at night.

How do inflammatory processes contribute to the progression of osteoarthritis?

Inflammation in osteoarthritis is triggered by joint abnormalities, trauma, or degeneration, leading to immune cell activation. Macrophages release cytokines like TNF-alpha and interleukin-1, which recruit more immune cells and produce enzymes that break down cartilage. This inflammatory process contributes to cartilage destruction and pain.

What role do osteoblasts and osteoclasts play in osteoarthritis?

Osteoblasts are bone-building cells, while osteoclasts break down bone. In osteoarthritis, osteoblasts try to repair damaged bone, leading to subchondral sclerosis (thickening of bone beneath cartilage) and the formation of osteophytes (bone spurs).

Why do some people with severe osteoarthritis experience minimal pain?

Pain perception varies among individuals. Some people may have high pain tolerance or less sensitivity to pain signals. Even with severe osteoarthritis, where joint damage is significant, these individuals might not feel intense pain, although they may still have mobility issues.

What are some non-pharmacological and pharmacological treatments for osteoarthritis?

Non-pharmacological treatments include weight loss, physiotherapy, use of walking aids, knee braces, heat/cold therapy, and acupuncture. Pharmacological treatments start with paracetamol, followed by topical or oral NSAIDs, glucocorticoid injections, viscosupplementation, and in severe cases, opioids or knee replacement surgery.