Understanding Osteoarthritis: Causes and Signs

Factors Contributing to Osteoarthritis

Osteoarthritis (OA) is influenced by various risk factors that fall into three categories: controllable local factors, controllable systemic factors, and unavoidable systemic factors.

Local controllable factors include elements like muscle strength, physical activity levels, joint injuries, joint alignment, and leg length discrepancies.

Systemic controllable factors encompass issues such as obesity and dietary habits.

Unchangeable systemic factors involve age, gender, genetics, and ethnicity.

1) Age

Age is a primary risk factor because years of joint stress lead to wear and tear, increasing the likelihood of OA. Women aged 60–64 are particularly vulnerable. Age-related changes like decreased joint tissue adaptability, increased bone turnover, and accumulation of damaging reactive oxygen species contribute to this risk.

2) Biological sex

Women tend to experience higher risks and more severe OA, primarily affecting hands, feet, and knees. Post-menopause severity suggests a link with estrogen levels. Other gender differences include bone strength, joint alignment, ligament laxity, and neuromuscular factors.

OA is often inherited, with over half of cases involving genetic factors. Specific genes tied to OA include those on chromosomes 2q, 7q22, and 11q. Younger adults often develop OA due to previous joint injuries, known as post-traumatic OA.

3) Obesity

Excess weight significantly raises the risk of OA in the knees and hips, especially in women. An increase of 5 BMI units raises knee OA risk by 35%, while losing 5kg reduces this risk by half. Obesity may also influence hand OA through metabolic and inflammatory effects.

4) Nutrition

Low levels of vitamins like D, C, and K are linked to increased OA risk. Vitamin D is vital for bone and cartilage health, though its precise role remains debated. Antioxidant vitamins like C help prevent cartilage breakdown, with higher intake associated with slower OA progression.

5) Joint use and occupational risks

Repetitive joint movements and occupations involving squatting, kneeling, or heavy lifting heighten OA risk. Athletes engaging in high-impact sports may face increased OA, often due to injuries, although running does not seem to increase hip or knee OA risk significantly.

6) Past joint injuries

Injuries like ACL tears and meniscal damage are strongly associated with developing OA, especially in knees. Damage leads to long-term joint changes and early osteoarthritis, often appearing within 10 years post-injury.

7) Muscle strength

Strong muscles support joint stability and absorb stress. Weakness increases OA risk, while stronger muscles decrease the chance of early disease onset and progression.

8) Joint alignment

Proper joint alignment distributes load evenly; misalignment can accelerate OA progression and lead to cartilage deterioration and bone damage.

Common Symptoms of Osteoarthritis

OA symptoms develop gradually and worsen over time. Typical signs include:

Joint pain during or after activity

Persistent ache

Sensitivity to touch

Stiffness after inactivity, like sleep

Reduced joint movement

Grinding or cracking sounds during motion

Bone spurs or lumps around joints

Swelling

Symptoms vary by affected joint. Hip OA causes groin or buttock pain; knee OA involves crepitus. Hand OA features swelling, redness, and nodules; foot OA affects the big toe or ankles. OA can impair mobility and increase fall and fracture risk.