Understanding Osteoarthritis: Bone Degeneration and Types

Osteoarthritis (OA) is the most common joint disorder, characterized by progressive loss of articular cartilage, subchondral bone remodeling, osteophyte formation, synovial inflammation, and capsular/ligamentous changes. It is a whole-joint disease, not merely "wear and tear."

Pathophysiology

• Chondrocyte dysfunction → imbalance of catabolic (MMPs, ADAMTS, cytokines IL-1β, TNF-α) vs. anabolic (collagen II, aggrecan) activity.
• Subchondral bone stiffening → increased cartilage stress.
• Synovitis (low-grade) → pain, effusion.
• Meniscus/ligament damage → altered biomechanics.

Classification

Type	Etiology	Typical Joints
Primary (Idiopathic)	Age-related, genetic, metabolic, biomechanical	Knees, hips, hands (DIP/PIP/CMC), spine, 1st MTP
Secondary	Post-traumatic, congenital (dysplasia), inflammatory (RA sequelae), metabolic (hemochromatosis, Ochronosis), endocrine (acromegaly), neuropathic (Charcot)	Any joint; often unilateral/atypical

Clinical Features

• Activity-related pain, improves with rest (later: rest pain, night pain).
• Morning stiffness <30 min (vs. >1h in inflammatory arthritis).
• Crepitus, bony enlargement (Heberden's/Bouchard's nodes), reduced ROM.

Diagnosis

Clinical + radiographic (joint space narrowing, osteophytes, subchondral sclerosis, cysts). MRI not routine.

Management (Core + Adjunct)

• Non-pharmacologic: Exercise (strengthening, aerobic, neuromuscular), weight loss (if overweight), education, assistive devices.
• Pharmacologic: Topical NSAIDs (knee/hand), oral NSAIDs (lowest dose, shortest duration, PPI if risk), duloxetine, intra-articular corticosteroids (flare), hyaluronic acid (conditional).
• Surgical: Arthroplasty (hip/knee) for refractory pain/disability; osteotomy (young, malalignment); arthroscopy not recommended for pure OA.

Multimodal, patient-centered approach delays progression and preserves function.