Histology · Year 1 · from Histology
Case 1: Osteoarthritis
Clinical Image
Source: Radiopaedia - Osteoarthritis - CC BY-NC-SA 3.0
Case Presentation
A 67-year-old retired postal worker presents with progressive right knee pain over the past 3 years. The pain is worse with activity and relieved by rest, with morning stiffness lasting less than 30 minutes. She has difficulty climbing stairs and notices a grinding sensation (crepitus) with knee movement. Physical examination reveals bony enlargement of the knee joint, reduced range of motion, and an antalgic gait. X-rays demonstrate classic osteoarthritis findings: joint space narrowing (indicating cartilage loss), subchondral sclerosis, osteophyte formation at joint margins, and small subchondral cysts (geodes). MRI confirms extensive loss of articular hyaline cartilage in the medial compartment. Her BMI is 32. Management includes weight loss counseling, physical therapy, acetaminophen and NSAIDs for pain, and discussion of eventual knee replacement surgery.
Key Learning Points
- Osteoarthritis is the most common joint disease, characterized by progressive degeneration of articular (hyaline) cartilage
- Articular cartilage lacks blood supply and perichondrium, severely limiting its capacity for self-repair
- Chondrocytes cannot proliferate effectively in adult cartilage, and the avascular matrix prevents inflammatory/repair cell infiltration
- Risk factors include age, obesity, joint trauma, and repetitive mechanical stress
- The histological progression shows fibrillation of cartilage surface, chondrocyte clustering, and eventual full-thickness cartilage loss