Causes of Arthritis and Arthrosis
Arthritis and arthrosis are caused by a complex interplay of genetic, mechanical, metabolic, and inflammatory factors that lead to joint degeneration and inflammation.
Key Causes of Arthritis and Arthrosis
Constitutional Risk Factors
- Age: Strong risk factor with age-related alterations contributing to systemic inflammation and accelerating joint degeneration 1
- Genetics: Significant hereditary component with 39-65% heritability independent of environmental factors 1, 2
- Sex: Women have higher prevalence, representing 78% of osteoarthritis diagnoses despite being only 51% of the general population 3
- Hormonal factors: Influence disease susceptibility 1
Mechanical Factors
- Abnormal joint loading: Joint malalignment contributes to uneven stress distribution 1
- Obesity: Increases mechanical loading on weight-bearing joints 3, 1
- Occupational factors:
- Sports/recreational activities: High-impact sports (football, hockey, skydiving) strongly associated with osteoarthritis development 3
- Previous joint trauma: Significantly increases risk of post-traumatic osteoarthritis 3
Inflammatory and Metabolic Mechanisms
- Low-grade inflammation: Now recognized as a key component rather than simple "wear and tear" 1, 4
- Synovial inflammation: Contributes to cartilage breakdown 3
- Metabolic factors: Associated with systemic inflammation affecting joints 1
- Gut microbiota: Emerging evidence suggests dysbiosis may link metabolic conditions to osteoarthritis 1
Cellular and Biochemical Processes
- Chondrocyte dysfunction: Age-related decline in chondrocyte numbers and viability due to nitric oxide-mediated apoptosis 2
- Diminished repair capacity: Remaining chondrocytes show reduced response to growth factors 2
- Proteoglycan alterations: Reduced synthesis and increased breakdown impairs cartilage resilience 2
- Matrix degradation: Enzymatic breakdown of cartilage components 2
Types of Arthritis and Their Specific Causes
Primary Osteoarthritis
- Idiopathic with unclear specific cause 5
- Results from natural aging processes affecting joint tissues 3
Secondary Osteoarthritis
- Develops as a consequence of pre-existing joint conditions or "pre-arthrosis" 5
- Caused by identifiable factors like:
Inflammatory Arthritis
- Characterized by autoimmune or inflammatory processes 6
- Requires different treatment approaches than non-inflammatory arthrosis 6
Clinical Manifestations and Progression
Symptomatic Progression
- Pain is the leading symptom in both conditions 6
- Arthrosis pain often related to:
- Activation (reactive secondary synovitis)
- Decompensation (periarthropathy and painful muscular irritations) 5
Structural Changes
- Joint space narrowing
- Subchondral sclerosis
- Osteophyte formation
- Cartilage degradation 1
Important Clinical Considerations
Risk Assessment
- Multiple risk factors often coexist and interact
- Patient-level factors (age, sex, genetics) combine with joint-specific factors (injury, mechanical stress) 3
Diagnostic Approach
- Consider all possible causes (idiopathic, autoimmune, degenerative, infectious, malignancy, traumatic, metabolic) in differential diagnosis 3
- Complete history and physical examination determine ranking of possible diagnoses 3
Common Pitfalls
- Overlooking modifiable risk factors like obesity and joint injury 7
- Failing to distinguish between inflammatory and non-inflammatory joint disease, which require different treatment approaches 6
- Attributing symptoms solely to radiographic findings, as degenerative changes correlate poorly with pain, especially in older adults 1
Understanding these multifactorial causes is essential for developing appropriate prevention strategies and treatment plans that address the underlying mechanisms of joint degeneration and inflammation.